WorldWideScience

Sample records for cascade laser applications

  1. Cascade laser applications: trends and challenges

    Science.gov (United States)

    d'Humières, B.; Margoto, Éric; Fazilleau, Yves

    2016-03-01

    When analyses need rapid measurements, cost effective monitoring and miniaturization, tunable semiconductor lasers can be very good sources. Indeed, applications like on-field environmental gas analysis or in-line industrial process control are becoming available thanks to the advantage of tunable semiconductor lasers. Advances in cascade lasers (CL) are revolutionizing Mid-IR spectroscopy with two alternatives: interband cascade lasers (ICL) in the 3-6μm spectrum and quantum cascade lasers (QCL), with more power from 3 to 300μm. The market is getting mature with strong players for driving applications like industry, environment, life science or transports. CL are not the only Mid-IR laser source. In fact, a strong competition is now taking place with other technologies like: OPO, VCSEL, Solid State lasers, Gas, SC Infrared or fiber lasers. In other words, CL have to conquer a share of the Mid-IR application market. Our study is a market analysis of CL technologies and their applications. It shows that improvements of components performance, along with the progress of infrared laser spectroscopy will drive the CL market growth. We compare CL technologies with other Mid-IR sources and estimate their share in each application market.

  2. Quantum Cascade Lasers Modulation and Applications

    Science.gov (United States)

    Luzhansky, Edward

    The mid-wave IR (MWIR) spectral band, extending from 3 to 5 microns, is considered to be a low loss atmospheric window. There are several spectral sub-bands with relatively low atmospheric attenuation in this region making it popular for various commercial and military applications. Relatively low thermal and solar background emissions, effective penetration through the natural and anthropogenic obscurants and eye safety add to the long list of advantages of MWIR wavelengths. Quantum Cascade Lasers are compact semiconductor devices capable of operating in MWIR spectrum. They are based on inter-subband transitions in a multiple-quantum-well (QW) hetero-structure, designed by means of band-structure engineering. The inter-subband nature of the optical transition has several key advantages. First, the emission wavelength is primarily a function of the QW thickness. This characteristic allows choosing well-understood and reliable semiconductors for the generation of light in a wavelength range of interest. Second, a cascade process in which tens of photons are generated per injected electron. This cascading process is behind the intrinsic high-power capabilities of QCLs. This dissertation is focused on modulation properties of Quantum Cascade Lasers. Both amplitude and phase/frequency modulations were studied including modulation bandwidth, modulation efficiency and chirp linearity. Research was consisted of the two major parts. In the first part we describe the theory of frequency modulation (FM) response of Distributed Feedback Quantum Cascade Lasers (DFB QCL). It includes cascading effect on the QCL's maximum modulation frequency. The "gain levering" effect for the maximum FM response of the two section QCLs was studied as well. In the second part of research we concentrated on the Pulse Position Amplitude Modulation of a single section QCL. The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept is

  3. New quantum cascade laser sources for sensing applications (Conference Presentation)

    Science.gov (United States)

    Troccoli, Mariano

    2017-05-01

    In this presentation we will review our most recent results on development of Quantum Cascade Lasers (QCLs) for analytical and industrial applications. QCLs have demonstrated the capability to cover the entire range of Mid-IR, Far-IR, and THz wavelengths by skillful tuning of the material design and composition and by use of intrinsic material properties via a set of techniques collectively called "bandgap engineering". The use of MOCVD, pioneered on industrial scale by AdTech Optics, has enabled the deployment of QCL devices into a diverse range of environments and applications. QCLs can be tailored to the specific application requirements due to their unprecedented flexibility in design and thanks to the leveraging of well-known III-V fabrication technologies inherited from the NIR domain. Nevertheless, several applications and new frontiers in R and D need the constant support of new developments in device features, capabilities, and performances. We have developed a wide range of devices, from high power, high efficiency multi-mode sources, to narrow-band, single mode devices with low-power consumption, and from non-linear, multi-wavelength generating devices to broadband sources and multi-emitter arrays. All our devices are grown and processed using MOCVD technology and allow us to attain competitive performances across the whole mid-IR spectral range. This talk will present an overview of our current achievements. References 1. M. Troccoli, "High power emission and single mode operation of quantum cascade lasers for industrial applications", J. Sel. Topics in Quantum Electron., 21 (6), 1-7 (2015). Invited Review. 2. Seungyong Jung, Aiting Jiang, Yifan Jiang, Karun Vijayraghavan, Xiaojun Wang, Mariano Troccoli, and Mikhail A. Belkin, "Broadly Tunable Monolithic Terahertz Quantum Cascade Laser Sources", Nature Comm. 5, 4267 (2014).. 3. Mariano Troccoli, Arkadiy Lyakh, Jenyu Fan, Xiaojun Wang, Richard Maulini, Alexei G Tsekoun, Rowel Go, C Kumar N Patel, "Long

  4. Quantum cascade laser: Applications in chemical detection and environmental monitoring

    Directory of Open Access Journals (Sweden)

    Radovanović Jelena

    2009-01-01

    Full Text Available In this paper we consider the structural parameter optimization of the active region of a GaAs-based quantum cascade laser in order to maximize the optical gain of the laser at the characteristic wavelengths, which are best suited for detection of pollutant gasses, such as SO2, HNO3, CH4, and NH3, in the ambient air by means of direct absorption. The procedure relies on applying elaborate tools for global optimization, such as the genetic algorithm. One of the important goals is to extend the applicability of a single active region design to the detection of several compounds absorbing at close wave-lengths, and this is achieved by introducing a strong external magnetic field perpendicularly to the epitaxial layers. The field causes two-dimensional continuous energy subbands to split into the series of discrete Landau levels. Since the arrangement of Landau levels depends strongly on the magnitude of the magnetic field, this enables one to control the population inversion in the active region, and hence the optical gain. Furthermore, strong effects of band non-parabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation properties and changing the target compound for detection. The numerical results are presented for quantum cascade laser structures designed to emit at specified wavelengths in the mid-infrared part of the spectrum.

  5. Application of quantum cascade lasers to trace gas analysis

    Science.gov (United States)

    Kosterev, A.; Wysocki, G.; Bakhirkin, Y.; So, S.; Lewicki, R.; Fraser, M.; Tittel, F.; Curl, R. F.

    2008-02-01

    Quantum cascade (QC) lasers are virtually ideal mid-infrared sources for trace gas monitoring. They can be fabricated to operate at any of a very wide range of wavelengths from ˜ 3 μm to ˜ 24 μm. Seizing the opportunity presented by mid-infrared QC lasers, several groups world-wide are actively applying them to trace gas sensing. Real world applications include environmental monitoring, industrial process control and biomedical diagnostics. In our laboratory we have explored the use of several methods for carrying out absorption spectroscopy with these sources, which include multipass absorption spectroscopy, cavity ring down spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), and quartz-enhanced photoacoustic spectroscopy (QEPAS).

  6. Applications of cw quantum cascade laser near 8 μm in gas sensing research

    KAUST Repository

    Sajid, Muhammad Bilal

    2014-01-01

    Quantum cascade laser based sensors operating near 8 μm to detect H2O2, C2H2, CH4, N2O and H2O are discussed and demonstrated for applications in chemical kinetics, combustion and spectroscopic measurements.

  7. Injectorless quantum cascade lasers

    Science.gov (United States)

    Katz, Simeon; Vizbaras, Augustinas; Meyer, Ralf; Amann, Markus-Christian

    2011-04-01

    This review focuses on recent progress on injectorless quantum cascade lasers, an increasingly attractive approach in comparison to the "classical" injectorbased concepts. This particularly holds for the wavelength range between 7 and 12 μm, where fundamental vibrational modes of many important molecules exist, so that sensor systems for medical, industrial and military applications highly benefit from these laser sources. The atmospheric transmission window between 8 and 12 μm, with very low damping, also enables free space applications like communication, military countermeasures, and environmental sensors. Injectorless devices operate closer to the original design principle for intersubband lasers as suggested by Suris and Kazarinov [Sov. Phys. Semicond. 5, 707 (1971)]. Therefore, a short description of their features is given in comparison to injectorbased devices. Within recent years, injectorless devices have seen rapid improvement in performance. Best injectorless devices reach threshold current densities of 450 A/cm2 at 300 K, a factor of 1.6 smaller than that for the best injectorbased devices. Their output efficiency has also increased from 2% to more than 7% within the last 2 years, reaching comparable levels and making the injectorless device concept competitive and very attractive for applications.

  8. Optical feedback effects on terahertz quantum cascade lasers: modelling and applications

    Science.gov (United States)

    Rakić, Aleksandar D.; Lim, Yah Leng; Taimre, Thomas; Agnew, Gary; Qi, Xiaoqiong; Bertling, Karl; Han, She; Wilson, Stephen J.; Kundu, Iman; Grier, Andrew; Ikonić, Zoran; Valavanis, Alexander; Demić, Aleksandar; Keeley, James; Li, Lianhe H.; Linfield, Edmund H.; Davies, A. Giles; Harrison, Paul; Ferguson, Blake; Walker, Graeme; Prow, Tarl; Indjin, Dragan; Soyer, H. Peter

    2016-11-01

    Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1-5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model.

  9. Applications of Quantum Cascade Laser Spectroscopy in the Analysis of Pharmaceutical Formulations.

    Science.gov (United States)

    Galán-Freyle, Nataly J; Pacheco-Londoño, Leonardo C; Román-Ospino, Andrés D; Hernandez-Rivera, Samuel P

    2016-09-01

    Quantum cascade laser spectroscopy was used to quantify active pharmaceutical ingredient content in a model formulation. The analyses were conducted in non-contact mode by mid-infrared diffuse reflectance. Measurements were carried out at a distance of 15 cm, covering the spectral range 1000-1600 cm(-1) Calibrations were generated by applying multivariate analysis using partial least squares models. Among the figures of merit of the proposed methodology are the high analytical sensitivity equivalent to 0.05% active pharmaceutical ingredient in the formulation, high repeatability (2.7%), high reproducibility (5.4%), and low limit of detection (1%). The relatively high power of the quantum-cascade-laser-based spectroscopic system resulted in the design of detection and quantification methodologies for pharmaceutical applications with high accuracy and precision that are comparable to those of methodologies based on near-infrared spectroscopy, attenuated total reflection mid-infrared Fourier transform infrared spectroscopy, and Raman spectroscopy. © The Author(s) 2016.

  10. Applications of a Mid-IR Quantum Cascade Laser in Gas Sensing Research

    KAUST Repository

    Sajid, Muhammad Bilal

    2015-05-01

    Laser absorption based sensors are extensively used in a variety of gas sensing areas such as combustion, atmospheric research, human breath analysis, and high resolution infrared spectroscopy. Quantum cascade lasers have recently emerged as high resolution, high power laser sources operating in mid infrared region and can have wide tunability range. These devices provide an opportunity to access stronger fundamental and combination vibrational bands located in mid infrared region than previously accessible weaker overtone vibrational bands located in near infrared region. Spectroscopic region near 8 µm contains strong vibrational bands of methane, acetylene, hydrogen peroxide, water vapor and nitrous oxide. These molecules have important applications in a wide range of applications. This thesis presents studies pertaining to spectroscopy and combustion applications. Advancements in combustion research are imperative to achieve lower emissions and higher efficiency in practical combustion devices such as gas turbines and engines. Accurate chemical kinetic models are critical to achieve predictive models which contain several thousand reactions and hundreds of species. These models need highly reliable experimental data for validation and improvements. Shock tubes are ideal devices to obtain such information. A shock tube is a homogenous, nearly constant volume, constant pressure, adiabatic and 0-D reactor. In combination with laser absorption sensors, shock tubes can be used to measure reaction rates and species time histories of several intermediates and products formed during pyrolysis and oxidation of fuels. This work describes measurement of the decomposition rate of hydrogen peroxide which is an important intermediate species controlling reactivity of combustion system in the intermediate temperature range. Spectroscopic parameters (linestrengths, broadening coefficients and temperature dependent coefficients) are determined for various transitions of

  11. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  12. Application of cascade lasers to detection of trace gaseous atmospheric pollutants

    Science.gov (United States)

    Miczuga, Marcin; Kopczyński, Krzysztof

    2016-12-01

    Understanding the impact of gaseous pollutants on the earth's atmosphere, as well as more and more felt by mankind negative effects of its contamination, result in increasing the level of environmental awareness and contribute to the intensification of actions aimed at reducing the emission of harmful gases into the atmosphere. At the same time, the extensive studies are conducted in order to continuously monitor the level of air contamination with harmful gases and the industry compliance with the standards limited the amount of emitted pollutants. Over recent years, there has been increasing use of cascade lasers and multi-pass cells in optical systems detecting the gaseous atmospheric pollutants and measuring the gas concentrations. The paper presents the use of a tunable quantum cascade laser as a source of the IR radiation in an advanced detection system enabling the trace gaseous atmospheric pollutants to be identified. Apart from the laser, the main elements of the system are: a multi-pass cell, an IR detector and a module for control and analysis. Operation of the system is exemplified by measuring the level of the air pollution with ammonia, carbon oxide and nitrous oxide.

  13. Physics of interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Bewley, W. W.; Merritt, C. D.; Canedy, C. L.; Kim, C. S.; Abell, J.; Meyer, J. R.; Kim, M.

    2012-01-01

    The interband cascade laser (ICL) is a unique device concept that combines the effective parallel connection of its multiple-quantum-well active regions, interband active transitions, and internal generation of electrons and holes at a semimetallic interface within each stage of the device. The internal generation of carriers becomes effective under bias, and the role of electrical injection is to replenish the carriers consumed by recombination processes. Major strides have been made toward fundamentally understanding the rich and intricate ICL physics, which has in turn led to dramatic improvements in the device performance. In this article, we review the physical principles of the ICL operation and designs of the active region, electron and hole injectors, and optical waveguide. The results for state-of- the-art ICLs spanning the 3-6 μm wavelength range are also briefly reviewed. The cw threshold input powers at room temperature are more than an order of magnitude lower than those for quantum cascade lasers throughout the mid-IR spectral range. This will lengthen battery lifetimes and greatly relax packaging and size/weight requirements for fielded sensing systems.

  14. Bipolar Cascade Vertical-Cavity Surface-Emitting Lasers for RF Photonic Link Applications

    National Research Council Canada - National Science Library

    Siskaninetz, William J

    2007-01-01

    ... the transition to a VCSEL structure is detailed. A novel approach prior to growing and characterizing BC VCSELs was to investigate bipolar cascade light emitting diodes which incorporate the microcavity designs and disentangles the VCSEL cavity...

  15. Progress in high-performance quantum cascade lasers

    Science.gov (United States)

    Lyakh, Arkadiy; Maulini, Richard; Tsekoun, Alexei G.; Patel, C. Kumar N.

    2010-11-01

    Because of their compact size, reliability, tunability, and convenience of direct electrical pumping, quantum cascade lasers have found a number of important civilian and defense applications in the midwave infrared and long-wave-infrared spectral range. Most of these applications would benefit from higher laser optical power and higher wall-plug efficiency. We describe some of the most important features of high-efficiency quantum cascade laser design and realization of high-power quantum cascade laser systems. Specifically, optimization of the active region and waveguide, thermal management on the chip level, and impact of the laser facet coating on laser efficiency and scaling of optical power with cavity length are discussed. Also, we present experimental results demonstrating multiwatt operation with reliability of at least several thousands of hours on a system level.

  16. Substrate-emitting ring interband cascade lasers

    Science.gov (United States)

    Holzbauer, Martin; Szedlak, Rolf; Detz, Hermann; Weih, Robert; Höfling, Sven; Schrenk, Werner; Koeth, Johannes; Strasser, Gottfried

    2017-10-01

    We demonstrate interband cascade lasers fabricated into ring-shaped cavities with vertical light emission through the substrate at a wavelength of λ ≈ 3.7 μm. The out-coupling mechanism is based on a metallized second-order distributed feedback grating. At room-temperature, a pulsed threshold current-density of 0.75 kA/cm2 and a temperature-tuning rate of 0.3 nm/°C are measured. In contrast to the azimuthal polarization of ring quantum cascade lasers, we observe a radial polarization of the projected nearfield of ring interband cascade lasers. These findings underline the fundamental physical difference between light generation in interband and intersubband cascade lasers, offering new perspectives for device integration.

  17. Seeded QED cascades in counterpropagating laser pulses.

    Science.gov (United States)

    Grismayer, T; Vranic, M; Martins, J L; Fonseca, R A; Silva, L O

    2017-02-01

    The growth rates of seeded QED cascades in counterpropagating lasers are calculated with first-principles two- and three-dimensional QED-PIC (particle-in-cell) simulations. The dependence of the growth rate on the laser polarization and intensity is compared with analytical models that support the findings of the simulations. The models provide insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. A discussion about the cascade's threshold is included, based on the analytical and numerical results. These results show that relativistic pair plasmas and efficient conversion from laser photons to γ rays can be observed with the typical intensities planned to operate on future ultraintense laser facilities such as ELI or Vulcan.

  18. Quantum cascade laser FM spectroscopy of explosives

    Science.gov (United States)

    Gutmann, Zach; Clasp, Trocia; Lue, Chris; Johnson, Tiffani; Ingle, Taylor; Jamison, Janet; Buchanan, Roger; Reeve, Scott

    2013-05-01

    Polyisobutylene is an industrial polymer that is widely used in a number of applications including the manufacture of military grade explosives. We have examined the vapor emanating from a series of different molecular weight samples of polyisobutylene using high resolution Quantum Cascade Laser FM spectroscopy. The vapor phase spectra all exhibit a rovibrational structure similar to that for the gas phase isobutylene molecule. We have assigned the structure in the 890 cm-1 and 1380 cm-1 regions to the isobutylene ν28 and ν7 fundamental bands respectively. These spectroscopic signatures may prove useful for infrared sensing applications. Here we will present the infrared signatures along with recent GCMS data from a sample of C4, utilizing solid-phase microextraction vapor collection fibers, which confirm the presence of isobutylene as one of the volatile bouquet species in RDX-based explosives.

  19. Gamma irradiation of Fabry–Perot interband cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Tanya L. [Pacific Northwest National Laboratory, Richland, Washington; Cannon, Bret D. [Pacific Northwest National Laboratory, Richland, Washington; Brauer, Carolyn S. [Pacific Northwest National Laboratory, Richland, Washington; Canedy, Chadwick L. [Naval Research Laboratory, Washington, DC; Kim, Chul Soo [Naval Research Laboratory, Washington, DC; Kim, Mijin [Sotera Defense Solutions, Inc., Columbia, Maryland; Merritt, Charles D. [Naval Research Laboratory, Washington, DC; Bewley, William W. [Naval Research Laboratory, Washington, DC; Vurgaftman, Igor [Naval Research Laboratory, Washington, DC; Meyer, Jerry R. [Naval Research Laboratory, Washington, DC

    2017-09-20

    Two Fabry-Perot interband cascade lasers (ICLs) were exposed to Cobalt-60 gamma rays for a dosage of 500 krad(Si) each, which is higher than is typically encountered in space applications. The ICLs do not show any significant changes in threshold current or slope efficiency, suggesting the suitability of ICLs for use in radiation environments.

  20. Surface emitting ring quantum cascade lasers for chemical sensing

    Science.gov (United States)

    Szedlak, Rolf; Hayden, Jakob; Martín-Mateos, Pedro; Holzbauer, Martin; Harrer, Andreas; Schwarz, Benedikt; Hinkov, Borislav; MacFarland, Donald; Zederbauer, Tobias; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Acedo, Pablo; Lendl, Bernhard; Strasser, Gottfried

    2018-01-01

    We review recent advances in chemical sensing applications based on surface emitting ring quantum cascade lasers (QCLs). Such lasers can be implemented in monolithically integrated on-chip laser/detector devices forming compact gas sensors, which are based on direct absorption spectroscopy according to the Beer-Lambert law. Furthermore, we present experimental results on radio frequency modulation up to 150 MHz of surface emitting ring QCLs. This technique provides detailed insight into the modulation characteristics of such lasers. The gained knowledge facilitates the utilization of ring QCLs in combination with spectroscopic techniques, such as heterodyne phase-sensitive dispersion spectroscopy for gas detection and analysis.

  1. Quantum Cascade Lasers in Biomedical Infrared Imaging.

    Science.gov (United States)

    Bird, Benjamin; Baker, Matthew J

    2015-10-01

    Technological advances, namely the integration of quantum cascade lasers (QCLs) within an infrared (IR) microscope, are enabling the development of valuable label-free biomedical-imaging tools capable of targeting and detecting salient chemical species within practical clinical timeframes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Quantum cascade lasers (QCLs) in biomedical spectroscopy.

    Science.gov (United States)

    Schwaighofer, Andreas; Brandstetter, Markus; Lendl, Bernhard

    2017-10-02

    Quantum cascade lasers (QCL) are the first room temperature semiconductor laser source for the mid-IR spectral region, triggering substantial development for the advancement of mid-IR spectroscopy. Mid-IR spectroscopy in general provides rapid, label-free and objective analysis, particularly important in the field of biomedical analysis. Due to their unique properties, QCLs offer new possibilities for development of analytical methods to enable quantification of clinically relevant concentration levels and to support medical diagnostics. Compared to FTIR spectroscopy, novel and elaborated measurement techniques can be implemented that allow miniaturized and portable instrumentation. This review illustrates the characteristics of QCLs with a particular focus on their benefits for biomedical analysis. Recent applications of QCL-based spectroscopy for analysis of a variety of clinically relevant samples including breath, urine, blood, interstitial fluid, and biopsy samples are summarized. Further potential for technical advancements is discussed in combination with future prospects for employment of QCL-based devices in routine and point-of-care diagnostics.

  3. Quantum cascade lasers for defense and security

    Science.gov (United States)

    Day, Timothy; Pushkarsky, Michael; Caffey, Dave; Cecchetti, Kristen; Arp, Ron; Whitmore, Alex; Henson, Michael; Takeuchi, Eric B.

    2013-10-01

    Quantum cascade laser (QCL) systems are mature and at the vanguard of a new generation of products that support military applications such as Infrared Countermeasures (IRCM) and targeting. The demanding product requirements for aircraft platforms that include reduced size, weight, power consumption and cost (SWaP-C) extends to portable, battery powered handheld products. QCL technology operates throughout the mid-wave (MWIR) and long-wave (LWIR) infrared to provide new capabilities that leverage existing thermal imaging cameras. In addition to their suitability for aircraft platforms, QCL products are a natural fit to meet operator demands for small, lightweight pointer and beacon capabilities. Field-testing of high power, lightweight, battery operated devices has demonstrated their utility across a range of air and ground applications. This talk will present an overview of QCL technology and the Defense and Security products and capabilities that are enabled by it. This talk will also provide an overview of the extensive environmental and performance testing associated with products based on QCL technology.

  4. THz quantum cascade lasers for standoff molecule detection.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wanke, Michael Clement; Lerttamrab, Maytee; Waldmueller, Ines

    2007-10-01

    Remote optical detection of molecules, agents, and energetic materials has many applications to national security interests. Currently there is significant interest in determining under what circumstances THz frequency coverage will aid in a complete sensing package. Sources of coherent THz frequency (i.e. 0.1 to 10 THz) electromagnetic radiation with requisite power levels, frequency agility, compactness and reliability represent the single greatest obstacle in establishing a THz technology base, but recent advances in semiconductor-based quantum cascade lasers (QCLs) offer huge improvements towards the ultimate THz source goals. This project advanced the development of narrow-linewidth THz quantum cascade lasers. We developed theoretical tools to guide the improvement of standard THz quantum cascade lasers, the investigation of nonlinear optics employing infrared QCLs, and the exploration of quantum coherence to improve QCL performance. The latter was aimed especially towards achieving high temperature operation. In addition we developed a computer algorithm capable of shifting the frequencies of an existing THz QCL to a different frequency and invented a new type of laser that may enable room temperature THz generation in a electrically driven solid-state source.

  5. Continuous Emission Monitoring of Tetrafluoromethane Using Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Peter Geiser

    2016-04-01

    Full Text Available Recent developments in quantum cascade lasers have enabled the development of new sensors for in-situ applications that have so far only been possible with extractive systems. In this work, a sensor is presented using a unique Wavelength Modulation Spectroscopy approach to measure tetrafluoromethane, a strong greenhouse gas. The sensor was characterized in a laboratory environment indicating a long-term detection limit of 20 ppb·m and a short-term value of well below 10 ppb·m. To demonstrate the feasibility of the sensor in a real-world environment, it was installed at an Alcoa aluminum smelter. A co-located Fourier Transform Infrared Spectrometer allowed direct comparison measurements of both systems. General agreement between the two methods was observed, leading to the conclusion that the developed in-situ quantum cascade laser based sensor has the potential to continuously measure tetrafluoromethane at aluminum smelters.

  6. Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers

    DEFF Research Database (Denmark)

    Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H. P.

    2016-01-01

    Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers...

  7. Numerical optimization of multi-wavelength and cascaded Raman fiber lasers

    Science.gov (United States)

    Cierullies, Sven; Renner, Hagen; Brinkmeyer, Ernst

    2003-03-01

    We present a model for the simulation and optimization of Raman fiber lasers. Applications include cascaded Raman lasers as well as lasers running on several wavelengths within one Stokes band. The model takes into account forward and backward propagating waves as well as Raman induced interactions between all pump and Stokes lines. Example calculations for both the simulation of a laser and the optimization of the mirror reflectivities for maximum overall output power and equalized laser lines are performed.

  8. Power scaling of high-efficiency 1.5 μm cascaded Raman fiber lasers.

    Science.gov (United States)

    Supradeepa, V R; Nicholson, Jeffrey W

    2013-07-15

    High-power fiber lasers operating at the 1.5 μm wavelength region have attractive features, such as eye safety and atmospheric transparency, and cascaded Raman fiber lasers offer a convenient method to obtain high-power sources at these wavelengths. A limitation to power scaling, however, has been the lower conversion efficiency of these lasers. We recently introduced a high-efficiency architecture for high-power cascaded Raman fiber lasers applicable for 1.5 μm fiber lasers. Here we demonstrate further power scaling using this new architecture. Using numerical simulations, we identify the ideal operating conditions for the new architecture. We demonstrate a high-efficiency 1480 nm cascaded Raman fiber laser with an output power of 301 W, comparable to record power levels achieved with rare-earth-doped fiber lasers in the 1.5 μm wavelength region.

  9. Enhanced performance of quantum cascade Raman laser

    Science.gov (United States)

    Yousefvand, Hossein Reza; Aahmadi, Vahid

    2015-05-01

    We present a self-consistent numerical approach for quantum cascade Raman laser (QC-RL) with a modified design to improve the device performance. Our modeling approach is based on monolithic integration of stimulated Raman scattering (SRS) and electrically pumped QC laser. The laser band structure utilizing techniques with both material-dependent effective mass and band nonparabolicity is calculated by solving the Schrodinger-Poisson equations self-consistently. A detailed analysis of output characteristics of the obtained structure is carried out within a simplified 4-level rate equations model taking into account the SRS process. The model accurately explains the operating characteristics found in QCLs, such as damping transient response and non-resonant behavior of modulation frequency response. Furthermore, modification of the structure is focused on improving the SRS in the QC-RL. This leads to an enhancement of the device performance such as threshold current, external quantum efficiency, conversion efficiency, turn-on delay and modulation response. The excellent agreement of the experimental data with the simulated light output-current characteristics confirms the validity of the model.

  10. Quantum cascade laser infrared spectroscopy of single cancer cells

    KAUST Repository

    Patel, Imran

    2017-03-27

    Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

  11. Terahertz Quantum Cascade Laser Based 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  12. Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

    Directory of Open Access Journals (Sweden)

    A. Pagies

    2016-06-01

    Full Text Available We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia in gas state. The low-power (<60 mW laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

  13. Progress in high-power continuous-wave quantum cascade lasers [Invited].

    Science.gov (United States)

    Figueiredo, Pedro; Suttinger, Matthew; Go, Rowel; Tsvid, Eugene; Patel, C Kumar N; Lyakh, Arkadiy

    2017-11-01

    Multi-watt continuous-wave room temperature operation with efficiency exceeding 10% has been demonstrated for quantum cascade lasers essentially in the entire mid-wave and long-wave infrared spectral regions. Along with interband cascade lasers, these devices are the only room-temperature lasers that directly convert electrical power into mid- and long-infrared optical power. In this paper, we review the progress in high-power quantum cascade lasers made over the last 10 years. Specifically, an overview of the most important active region, waveguide, and thermal design techniques is presented, and various aspects of die packaging for high-power applications are discussed. Prospects of power scaling with lateral device dimensions for reaching optical power level in the range from 10 W to 20 W are also analyzed. Finally, coherent and spectral beam-combining techniques for very high-power infrared platforms are discussed.

  14. Deformed microcavity quantum cascade lasers with directional emission

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qijie; Yan Changling; Diehl, Laurent; Yu Nanfang; Pfluegl, Christian; Belkin, Mikhail A; Capasso, Federico [School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Hentschel, Martina [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Wiersig, Jan [Institut fuer Theoretische Physik, Universitaet Magdeburg, Postfach 4120, D-39016 Magdeburg (Germany); Edamura, Tadataka; Yamanishi, Masamichi; Kan, Hirofumi [Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu 434-8601 (Japan)], E-mail: ldiehl@seas.harvard.edu, E-mail: capasso@seas.harvard.edu

    2009-12-15

    We report the experimental realization of deformed microcavity quantum cascade lasers (QCLs) with a Limacon-shaped chaotic resonator. Directional light emission with a beam divergence of {theta}{sub parallel}{approx}33 deg. from QCLs emitting at {lambda}{approx}10 {mu}m was obtained in the plane of the cavity for deformations in the range 0.37<{epsilon}<0.43. An excellent agreement between measured and calculated far-field profiles was found. Both simulations and experiments show that the Limacon-shaped microcavity preserves whispering gallery-like modes with high Q-factors for low deformations ({epsilon}<0.50). In addition, while the measured spectra show a transition from whispering gallery-like modes to a more complex mode structure at higher pumping currents, we observed 'universal far-field behavior' for different intracavity mode distributions in the Limacon microcavity, which can be explained by the distribution of unstable manifolds in ray optics simulations. Furthermore, the performance of the deformed microcavity lasers is robust with respect to variations of the deformation near its optimum value {epsilon}=0.40, which implies that this structure reduces the requirements on photolithography fabrication. The successful realization of these microcavity lasers may lead to applications in optoelectronics.

  15. Intracavity laser absorption spectroscopy using mid-IR quantum cascade laser

    Science.gov (United States)

    Medhi, G.; Muravjov, A. V.; Saxena, H.; Fredricksen, C. J.; Brusentsova, T.; Peale, R. E.; Edwards, O.

    2011-06-01

    Intracavity Laser Absorption Spectroscopy (ICLAS) at IR wavelengths offers an opportunity for spectral sensing with sufficient sensitivity to detect vapors of low vapor pressure compounds such as explosives. Reported here are key enabling technologies for this approach, including multi-mode external-cavity quantum cascade lasers and a scanning Fabry-Perot spectrometer to analyze the laser mode spectrum in the presence of a molecular intracavity absorber. Reported also is the design of a compact integrated data acquisition and control system. Applications include military and commercial sensing for threat compounds, chemical gases, biological aerosols, drugs, and banned or invasive plants or animals, bio-medical breath analysis, and terrestrial or planetary atmosphere science.

  16. Mid-infrared absorption spectroscopy using quantum cascade lasers

    Science.gov (United States)

    Haibach, Fred; Erlich, Adam; Deutsch, Erik

    2011-06-01

    Block Engineering has developed an absorption spectroscopy system based on widely tunable Quantum Cascade Lasers (QCL). The QCL spectrometer rapidly cycles through a user-selected range in the mid-infrared spectrum, between 6 to 12 μm (1667 to 833 cm-1), to detect and identify substances on surfaces based on their absorption characteristics from a standoff distance of up to 2 feet with an eye-safe laser. It can also analyze vapors and liquids in a single device. For military applications, the QCL spectrometer has demonstrated trace explosive, chemical warfare agent (CWA), and toxic industrial chemical (TIC) detection and analysis. The QCL's higher power density enables measurements from diffuse and highly absorbing materials and substrates. Other advantages over Fourier Transform Infrared (FTIR) spectroscopy include portability, ruggedness, rapid analysis, and the ability to function from a distance through free space or a fiber optic probe. This paper will discuss the basic technology behind the system and the empirical data on various safety and security applications.

  17. Freedom from band-gap slavery: from diode lasers to quantum cascade lasers

    Science.gov (United States)

    Capasso, Federico

    2010-02-01

    Semiconductor heterostructure lasers, for which Alferov and Kromer received part of the Nobel Prize in Physics in 2000, are the workhorse of technologies such as optical communications, optical recording, supermarket scanners, laser printers and fax machines. They exhibit high performance in the visible and near infrared and rely for their operation on electrons and holes emitting photons across the semiconductor bandgap. This mechanism turns into a curse at longer wavelengths (mid-infrared) because as the bandgap, shrinks laser operation becomes much more sensitive to temperature, material defects and processing. Quantum Cascade Laser (QCL), invented in 1994, rely on a radically different process for light emission. QCLs are unipolar devices in which electrons undergo transitions between quantum well energy levels and are recycled through many stages emitting a cascade of photons. Thus by suitable tailoring of the layers' thickness, using the same heterostructure material, they can lase across the molecular fingerprint region from 3 to 25 microns and beyond into the far-infrared and submillimiter wave spectrum. High power cw room temperature QCLs and QCLs with large continuous single mode tuning range have found many applications (infrared countermeasures, spectroscopy, trace gas analysis and atmospheric chemistry) and are commercially available. )

  18. Recent progress on gas sensor based on quantum cascade lasers and hollow fiber waveguides

    Science.gov (United States)

    Liu, Ningwu; Sun, Juan; Deng, Hao; Ding, Junya; Zhang, Lei; Li, Jingsong

    2017-02-01

    Mid-infrared laser spectroscopy provides an ideal platform for trace gas sensing applications. Despite this potential, early MIR sensing applications were limited due to the size of the involved optical components, e.g. light sources and sample cells. A potential solution to this demand is the integration of hollow fiber waveguide with novelty quantum cascade lasers.Recently QCLs had great improvements in power, efficiency and wavelength range, which made the miniaturized platforms for gas sensing maintaining or even enhancing the achievable sensitivity conceivable. So that the miniaturization of QCLs and HWGs can be evolved into a mini sensor, which may be tailored to a variety of real-time and in situ applications ranging from environmental monitoring to workplace safety surveillance. In this article, we introduce QCLs and HWGs, display the applications of HWG based on QCL gas sensing and discuss future strategies for hollow fiber coupled quantum cascade laser gas sensor technology.

  19. Mode Locking of Quantum Cascade Lasers

    National Research Council Canada - National Science Library

    Capasso, Federico; Kaertner, Franz X

    2007-01-01

    .... A wide variety of experimental data on multimode regimes is presented. Lasers with narrow active region and/or with metal coating on the sides tend to develop a splitting in the spectrum, approximately equal to twice the Rabi frequency...

  20. Experimental Investigation of Hot Carriers in Terahertz Quantum Cascade Lasers

    Science.gov (United States)

    Scamarcio, G.; Vitiello, M. S.; Spagnolo, V.

    2008-03-01

    The nature of the electron distribution and the electron-lattice energy relaxation phenomena in all classes of quantum cascade lasers operating in the THz range, namely, resonant-phonon, bound-to-continuum, and interlaced photon-phonon designs are reviewed. Thermalized hot-electron distributions are found in all cases. However, electronic temperatures of individual conduction subband are strongly influenced by the specific quantum design and the actual electron-lattice energy relaxation channels. A wealth of information was obtained both below and above laser threshold from the analysis of micro-probe band-to-band photoluminescence spectra recorded with a spatial resolution of ≈ 2 μm. The influence of the detailed knowledge of the hot electron distributions on the design of improved THz quantum cascade lasers aiming at high temperature operation will be discussed.

  1. Delay time calculation for dual-wavelength quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hamadou, A., E-mail: abd-hamado@yahoo.fr [Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université de Bordj Bou Arreridj 34000 (Algeria); Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Lamari, S. [Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 (Algeria); Thobel, J.-L. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR 8520, Université Lille1, Avenue Poincaré, BP 60069, 59652 Villeneuve d' Ascq Cédex (France)

    2013-11-28

    In this paper, we calculate the turn-on delay (t{sub th}) and buildup (Δt) times of a midinfrared quantum cascade laser operating simultaneously on two laser lines having a common upper level. The approach is based on the four-level rate equations model describing the variation of the electron number in the states and the photon number present within the cavity. We obtain simple analytical formulae for the turn-on delay and buildup times that determine the delay times and numerically apply our results to both the single and bimode states of a quantum cascade laser, in addition the effects of current injection on t{sub th} and Δt are explored.

  2. Terahertz quantum-cascade lasers based on an interlaced photon-phonon cascade

    Science.gov (United States)

    Köhler, Rüdeger; Tredicucci, Alessandro; Mauro, Cosimo; Beltram, Fabio; Beere, Harvey E.; Linfield, Edmund H.; Davies, A. Giles; Ritchie, David A.

    2004-02-01

    A THz (λ˜80 μm) quantum-cascade laser utilizing alternating photon- and phonon-emitting stages has been developed to achieve efficient extraction of electrons from the lower laser level. Thermal backfilling of electrons is drastically reduced leading to an operation up to 95 K and a weak temperature dependence of the power versus current slope efficiency. The threshold current density is 280 A cm-2 at 6 K and increases to 580 A cm-2 at 90 K. Peak output powers of 10 mW at 30 K and 4 mW at 80 K are obtained.

  3. High power and single mode quantum cascade lasers.

    Science.gov (United States)

    Bismuto, Alfredo; Bidaux, Yves; Blaser, Stéphane; Terazzi, Romain; Gresch, Tobias; Rochat, Michel; Muller, Antoine; Bonzon, Christopher; Faist, Jerome

    2016-05-16

    We present a single mode quantum cascade laser with nearly 1 W optical power. A buried distributed feedback reflector is used on the back section for wavelength selection. The laser is 6 mm long, 3.5 μm wide, mounted episide-up and the laser facets are left uncoated. Laser emission is centered at 4.68 μm. Single-mode operation with a side mode suppression ratio of more than 30 dB is obtained in whole range of operation. Farfield measurements prove a symmetric, single transverse-mode emission in TM00-mode with typical divergences of 41° and 33° in the vertical and horizontal direction respectively. This work shows the potential for simple fabrication of high power lasers compatible with standard DFB processing.

  4. Single-Mode, Distributed Feedback Interband Cascade Lasers

    Science.gov (United States)

    Frez, Clifford F. (Inventor); Borgentun, Carl E. (Inventor); Briggs, Ryan M. (Inventor); Bagheri, Mahmood (Inventor); Forouhar, Siamak (Inventor)

    2016-01-01

    Single-mode, distributed feedback interband cascade lasers (ICLs) using distributed-feedback gratings (e.g., lateral Bragg gratings) and methods of fabricating such ICLs are provided. The ICLs incorporate distributed-feedback gratings that are formed above the laser active region and adjacent the ridge waveguide (RWG) of the ICL. The ICLs may incorporate a double-ridge system comprising an optical confinement structure (e.g., a RWG) disposed above the laser active region that comprises the first ridge of the double ridge system, a DFB grating (e.g., lateral Bragg grating) disposed above the laser active region and adjacent the optical confinement structure, and an electric confinement structure that passes at least partially through the laser active region and that defines the boundary of the second ridge comprises and the termination of the DFB grating.

  5. Low Power Consumption Substrate-Emitting DFB Quantum Cascade Lasers

    Science.gov (United States)

    Liu, Chuan-Wei; Zhang, Jin-Chuan; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    In the present work, an ultra-low power consumption substrate-emitting distributed feedback (DFB) quantum cascade laser (QCL) was developed. The continuous-wave (CW) threshold power dissipation is reduced to 0.43 W at 25 °C by shortening the cavity length to 0.5 mm and depositing high-reflectivity (HR) coating on both facets. As far as we know, this is the recorded threshold power dissipation of QCLs in the same conditions. Single-mode emission was achieved by employing a buried second-order grating. Mode-hop free emission can be observed within a wide temperature range from 15 to 105 °C in CW mode. The divergence angles are 22.5o and 1.94o in the ridge-width direction and cavity-length direction, respectively. The maximum optical power in CW operation was 2.4 mW at 25 °C, which is sufficient to spectroscopy applications.

  6. From quantum cascade to super cascade laser a new laser design paradigm for broad spectral emission & a re-examination of current spreading

    Science.gov (United States)

    Le, Loan T.

    Over the span of more than 20 years of development, the Quantum Cascade (QC) laser has positioned itself as the most viable mid-infrared (mid-IR) light source. Today's QC lasers emit watts of continuous wave power at room temperature. Despite significant progress, the mid-IR region remains vastly under-utilized. State-of-the-art QC lasers are found in high power defense applications and detection of trace gases with narrow absorption lines. A large number of applications, however, do not require so much power, but rather, a broadly tunable laser source to detect molecules with broad absorption features. As such, a QC laser that is broadly tunable over the entire biochemical fingerprinting region remains the missing link to markets such as non- invasive biomedical diagnostics, food safety, and stand-off detection in turbid media. In this thesis, we detail how we utilized the inherent flexibility of the QC design space to conceive a new type of laser with the potential to bridge that missing link of the QC laser to large commercial markets. Our design concept, the Super Cascade (SC) laser, works contrary to conventional laser design principle by supporting multiple independent optical transitions, each contributing to broadening the gain spectrum. We have demonstrated a room temperature laser gain medium with electroluminescence spanning 3.3-12.5 ?m and laser emission from 6.2-12.5 ?m, the record spectral width for any solid state laser gain medium. This gain bandwidth covers the entire biochemical fingerprinting region. The achievement of such a spectrally broad gain medium presents engineering challenges of how to optimally utilize the bandwidth. As of this work, a monolithi- cally integrated array of Distributed Feedback QC (DFB-QC) lasers is one of the most promising ways to fully utilize the SC gain bandwidth. Therefore, in this thesis, we explore ways of improving the yield and ease of fabrication of DFB-QC lasers, including a re-examination of the role of

  7. Remote Chemical Sensing Using Quantum Cascade Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Harper, Warren W.; Schultz, John F.

    2003-01-30

    Spectroscopic chemical sensing research at Pacific Northwest National Laboratory (PNNL) is focused on developing advanced sensors for detecting the production of nuclear, chemical, or biological weapons; use of chemical weapons; or the presence of explosives, firearms, narcotics, or other contraband of significance to homeland security in airports, cargo terminals, public buildings, or other sensitive locations. For most of these missions, the signature chemicals are expected to occur in very low concentrations, and in mixture with ambient air or airborne waste streams that contain large numbers of other species that may interfere with spectroscopic detection, or be mistaken for signatures of illicit activity. PNNL’s emphasis is therefore on developing remote and sampling sensors with extreme sensitivity, and resistance to interferents, or selectivity. PNNL’s research activities include: 1. Identification of signature chemicals and quantification of their spectral characteristics, 2. Identification and development of laser and other technologies that enable breakthroughs in sensitivity and selectivity, 3. Development of promising sensing techniques through experimentation and modeling the physical phenomenology and practical engineering limitations affecting their performance, and 4. Development and testing of data collection methods and analysis algorithms. Close coordination of all aspects of the research is important to ensure that all parts are focused on productive avenues of investigation. Close coordination of experimental development and numerical modeling is particularly important because the theoretical component provides understanding and predictive capability, while the experiments validate calculations and ensure that all phenomena and engineering limitations are considered.

  8. MID-INFRARED QUANTUM CASCADE LASERS

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... for several applications including environmental sensing, pollution monitoring, and medical appli- cations. In this tutorial review we present ... a beam of ammonia (NH3) gas, in a microwave de- vice called the maser (microwave ..... plasma monitoring, in law enforcement for drug and explosive detection, in ...

  9. A hybrid plasmonic waveguide terahertz quantum cascade laser

    Science.gov (United States)

    Degl'Innocenti, Riccardo; Shah, Yash D.; Wallis, Robert; Klimont, Adam; Ren, Yuan; Jessop, David S.; Beere, Harvey E.; Ritchie, David A.

    2015-02-01

    We present the realization of a quantum cascade laser emitting at around 2.85 THz, based on a hybrid plasmonic waveguide with a low refractive index dielectric cladding. This hybrid waveguide design allows the performance of a double-metal waveguide to be retained, while improving the emission far-field. A set of lasers based on the same active region material were fabricated with different metal layer thicknesses. A detailed characterization of the performance of these lasers revealed that there is an optimal trade-off that yields the best far-field emission and the maximum temperature of operation. By exploiting the pure plasmonic mode of these waveguides, the standard operation conditions of a double-metal quantum cascade laser were retrieved, such that the maximum operating temperature of these devices is not affected by the process. These results pave the way to realizing a class of integrated devices working in the terahertz range which could be further exploited to fabricate terahertz on-chip circuitry.

  10. Real time imaging analysis using a terahertz quantum cascade laser and a microbolometer focal plane array

    OpenAIRE

    Buchanan, Kevin William.

    2008-01-01

    It is widely published that the terahertz (THz) spectral range has potential for imaging in the fields of military and security applications. The Sensors Research Laboratory previously achieved real-time imaging of concealed objects using a 1mW quantum cascade laser (QCL) and an uncooled vanadium oxide/silicon nitride based microbolometer. This thesis introduces an amorphous silicon based microbolometer with improved NETD in the 8-12 micrometer infrared spectral range. The QCL is usually oper...

  11. Terahertz difference frequency generation in quantum cascade lasers on silicon

    Science.gov (United States)

    Jung, Seungyong; Kim, Jae Hyun; Jiang, Yifan; Vijayraghavan, Karun; Belkin, Mikhail A.

    2017-02-01

    We demonstrate that an application of a III-V-on-silicon hybrid concept to terahertz (THz) Cherenkov difference frequency generation (DFG) quantum cascade laser (QCL) sources (THz DFG-QCLs) can dramatically improve THz output power and mid-infrared-to-THz conversion efficiency. Completely processed THz DFG-QCLs grown on a 660-μm-thick native InP substrate are transfer-printed onto a 1-mm-thick high-resistive Si substrate using a 100-nm-thick SU-8 as an adhesive layer. Room temperature device performance of the reference InP and hybrid Si THz DFG-QCLs of the same ridge width (22 μm) and cavity length (4.2 mm) have been experimentally compared. The target THz frequency of 3.5 THz is selected for both devices using the dual-period first order surface gratings to select the mid-infrared pump wavelength of 994 cm-1 and 1110 cm-1. At the maximum bias current, the reference InP and hybrid Si devices produced THz power of 50 μW and 270 μW, respectively. The mid-infrared-to-THz conversion efficiency corresponds to 60 μW/W2 and 480 μW/W2, respectively, resulting in 5 times higher THz power and 8 times higher conversion efficiency from the best-performing hybrid devices. A hybrid Si device integrated in a Littrow external-cavity setup showed wavelength tuning from 1.3 THz to 4.3 THz with beam-steering free operation.

  12. High frequency modulation capabilities and quasi single-sideband emission from a quantum cascade laser.

    Science.gov (United States)

    Hangauer, Andreas; Spinner, Georg; Nikodem, Michal; Wysocki, Gerard

    2014-09-22

    Both intensity- (IM) and frequency-modulation (FM) behavior of a directly modulated quantum cascade laser (QCL) are measured from 300 Hz to 1.7 GHz. Quantitative measurements of tuning coefficients has been performed and the transition from thermal- to electronic-tuning is clearly observed. A very specific FM behavior of QCLs has been identified which allows for optical quasi single sideband (SSB) modulation through current injection and has not been observed in directly modulated semiconductor lasers before. This predestines QCLs in applications where SSB is required, such as telecommunication or high speed spectroscopy. The experimental procedure and theoretical modeling for data extraction is discussed.

  13. External amplitude and frequency modulation of a terahertz quantum cascade laser using metamaterial/graphene devices.

    Science.gov (United States)

    Kindness, S J; Jessop, D S; Wei, B; Wallis, R; Kamboj, V S; Xiao, L; Ren, Y; Braeuninger-Weimer, P; Aria, A I; Hofmann, S; Beere, H E; Ritchie, D A; Degl'Innocenti, R

    2017-08-09

    Active control of the amplitude and frequency of terahertz sources is an essential prerequisite for exploiting a myriad of terahertz applications in imaging, spectroscopy, and communications. Here we present a optoelectronic, external modulation technique applied to a terahertz quantum cascade laser which holds the promise of addressing a number of important challenges in this research area. A hybrid metamaterial/graphene device is implemented into an external cavity set-up allowing for optoelectronic tuning of feedback into a quantum cascade laser. We demonstrate powerful, all-electronic, control over the amplitude and frequency of the laser output. Full laser switching is performed by electrostatic gating of the metamaterial/graphene device, demonstrating a modulation depth of 100%. External control of the emission spectrum is also achieved, highlighting the flexibility of this feedback method. By taking advantage of the frequency dispersive reflectivity of the metamaterial array, different modes of the QCL output are selectively suppressed using lithographic tuning and single mode operation of the multi-mode laser is enforced. Side mode suppression is electrically modulated from ~6 dB to ~21 dB, demonstrating active, optoelectronic modulation of the laser frequency content between multi-mode and single mode operation.

  14. Density matrix Monte Carlo modeling of quantum cascade lasers

    Science.gov (United States)

    Jirauschek, Christian

    2017-10-01

    By including elements of the density matrix formalism, the semiclassical ensemble Monte Carlo method for carrier transport is extended to incorporate incoherent tunneling, known to play an important role in quantum cascade lasers (QCLs). In particular, this effect dominates electron transport across thick injection barriers, which are frequently used in terahertz QCL designs. A self-consistent model for quantum mechanical dephasing is implemented, eliminating the need for empirical simulation parameters. Our modeling approach is validated against available experimental data for different types of terahertz QCL designs.

  15. Photo-vibrational spectroscopy using quantum cascade laser and laser Doppler vibrometer

    Science.gov (United States)

    Liu, Huan; Hu, Qi; Xie, Jiecheng; Fu, Yu

    2017-06-01

    Photoacoustic/photothermal spectroscopy is an established technique for detection of chemicals and explosives. However, prior sample preparation is required and the analysis is conducted in a sealed space with a high-sensitivity sensor coupled with a lock-in amplifier, limiting the technique to applications in a controllable laboratory environment. Hence, this technique may not be suitable for defense and security applications where the detection of explosives or hazardous chemicals is required in an open environment at a safe standoff distance. In this study, chemicals in various forms were excited by an intensity-modulated quantum cascade laser (QCL), while a laser Doppler vibrometer (LDV) was applied to detect the vibration signal resulting from the photocoustic/photothermal effect. The photo-vibrational spectrum obtained by scanning the QCL's wavelength in MIR range, coincides well with the corresponding spectrum obtained using typical FTIR equipment. The experiment in short and long standoff distances demonstrated that the LDV is a capable sensor for chemical detection in an open environment.

  16. Terahertz Quantum Cascade Laser With Efficient Coupling and Beam Profile

    Science.gov (United States)

    Chattopadhyay, Goutam; Kawamura, Jonathan H.; Lin, Robert H.; Williams, Benjamin

    2012-01-01

    Quantum cascade lasers (QCLs) are unipolar semiconductor lasers, where the wavelength of emitted radiation is determined by the engineering of quantum states within the conduction band in coupled multiple-quantum-well heterostructures to have the desired energy separation. The recent development of terahertz QCLs has provided a new generation of solid-state sources for radiation in the terahertz frequency range. Terahertz QCLs have been demonstrated from 0.84 to 5.0 THz both in pulsed mode and continuous wave mode (CW mode). The approach employs a resonant-phonon depopulation concept. The metal-metal (MM) waveguide fabrication is performed using Cu-Cu thermo-compression bonding to bond the GaAs/AlGaAs epitaxial layer to a GaAs receptor wafer.

  17. Optimization of quantum cascade laser operation by geometric design of cascade active band in open and closed models

    Directory of Open Access Journals (Sweden)

    M.V. Tkach

    2013-01-01

    Full Text Available Using the effective mass and rectangular potential approximations, the theory of electron dynamic conductivity is developed for the plane multilayer resonance tunnel structure placed into a constant electric field within the model of open nanosystem, and oscillator forces of quantum transitions within the model of closed nanosystem. For the experimentally produced quantum cascade laser with four-barrier active band of separate cascade, it is proven that just the theory of dynamic conductivity in the model of open cascade most adequately describes the radiation of high frequency electromagnetic field while the electrons transport through the resonance tunnel structure driven by a constant electric field.

  18. Multi-species trace gas analysis with dual-wavelength quantum cascade laser

    Science.gov (United States)

    Jágerská, Jana; Tuzson, Béla; Looser, Herbert; Jouy, Pierre; Hugi, Andreas; Mangold, Markus; Soltic, Patrik; Faist, Jérôme; Emmenegger, Lukas

    2015-04-01

    Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly appealing for a large variety of applications ranging from air quality monitoring, medical breath analysis to industrial process control. However, state-of-the-art distributed-feedback (DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally leads to one-laser-one-compound measurement strategy. Thus, multi-species detection involves several lasers and elaborate beam combining solutions [1]. This makes them bulky, costly, and highly sensitive to optical alignment, which limits their field deployment. In this paper, we explore an alternative measurement concept based on a dual-wavelength quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct wavelengths using a succession of two DFB gratings with different periodicities and a common waveguide to produce one output beam. The laser design was optimized for NOx measurements and correspondingly emits single-mode at 5.26 and 6.25 μm. Electrical separation of the respective laser sections makes it possible to address each wavelength independently. Thereby, it is possible to detect NO and NO2 species with one laser using the same optical path, without any beam combining optics, i.e. in a compact and cost-efficient single-path optical setup. Operated in a time-division multiplexed mode, the spectrometer reaches detection limits at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system was validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as monitoring the pollution at a suburban site. [1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, and L. Emmenegger, 'Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy,' Atmospheric Measurement Techniques 6, 927-936 (2013

  19. Quantum cascade semiconductor infrared and far-infrared lasers: from trace gas sensing to non-linear optics.

    Science.gov (United States)

    Duxbury, Geoffrey; Langford, Nigel; McCulloch, Michael T; Wright, Stephen

    2005-11-01

    The Quantum cascade (QC) laser is an entirely new type of semiconductor device in which the laser wavelength depends on the band-gap engineering. It can be made to operate over a much larger range than lead salt lasers, covering significant parts of both the infrared and submillimetre regions, and with higher output power. In this tutorial review we survey some of the applications of these new lasers, which range from trace gas detection for atmospheric or medical purposes to sub-Doppler and time dependent non-linear spectroscopy.

  20. Investigations of the polarization behavior of quantum cascade lasers by Stokes parameters.

    Science.gov (United States)

    Janassek, Patrick; Hartmann, Sébastien; Molitor, Andreas; Michel, Florian; Elsäßer, Wolfgang

    2016-01-15

    We experimentally investigate the full polarization behavior of mid-infrared emitting quantum cascade lasers (QCLs) in terms of measuring the complete Stokes parameters, instead of only projecting them on a linear polarization basis. We demonstrate that besides the pre-dominant linear TM polarization of the emitted light as governed by the selection rules of the intersubband transition, small non-TM contributions, e.g., circularly polarized light, are present reflecting the birefringent behavior of the semiconductor quantum well waveguide. Surprisingly unique is the persistence of these polarization properties well below laser threshold. These investigations give further insight into understanding, manipulating, and exploiting the polarization properties of QCLs, both from a laser point of view and with respect toward applications.

  1. Continuous wave room temperature external ring cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  2. Integration of quantum cascade lasers and passive waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, Juan, E-mail: juan.montoya@ll.mit.edu; Wang, Christine; Goyal, Anish; Creedon, Kevin; Connors, Michael; Daulton, Jeffrey; Donnelly, Joseph; Missaggia, Leo; Aleshire, Chris; Sanchez-Rubio, Antonio; Herzog, William [MIT Lincoln Laboratory, 244 Wood St, Lexington, Massachusetts 02420 (United States)

    2015-07-20

    We report on monolithic integration of active quantum cascade laser (QCL) materials with passive waveguides formed by using proton implantation. Proton implantation reduces the electron concentration in the QCL layers by creating deep levels that trap carriers. This strongly reduces the intersubband absorption and the free-carrier absorption in the gain region and surrounding layers, thus significantly reducing optical loss. We have measured loss as low as α = 0.33 cm{sup −1} in λ = 9.6 μm wavelength proton-implanted QCL material. We have also demonstrated lasing in active-passive integrated waveguides. This simple integration technique is anticipated to enable low-cost fabrication in infrared photonic integrated circuits in the mid-infrared (λ ∼ 3–16 μm)

  3. Tunable single-mode slot waveguide quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Bo; Tao, Jin; Quan Zeng, Yong [NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore (Singapore); Hui Li, Xiao [NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wu, Sheng [Power Energy and Environmental Research Institute, Covina, California, 91722 (United States); Jie Wang, Qi, E-mail: qjwang@ntu.edu.sg [NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2014-05-19

    We report experimental demonstration of tunable, monolithic, single-mode quantum cascade lasers (QCLs) at ∼10 μm with a two-section etched slot structure. A single-mode tuning range of 77 cm{sup −1} (785 nm), corresponding to ∼7.8% of the relative tuning range, was realized with a ∼20 dB side mode suppression ratio within the whole tuning range. Compared with integrated distributed feedback QCLs, our devices have the advantages of easy fabrication and a broader tuning range. Further theoretical analyses and numerical simulations show that it is possible to achieve a broad continuous tuning range by optimizing the slot structures. The proposed slot-waveguide design could provide an alternative but simple approach to the existing tuning schemes for realizing broadly continuous tunable single-mode QCLs.

  4. Contributed review: quantum cascade laser based photoacoustic detection of explosives.

    Science.gov (United States)

    Li, J S; Yu, B; Fischer, H; Chen, W; Yalin, A P

    2015-03-01

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

  5. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe

    2015-01-01

    Two stage cascaded converters are widely used in bidirectional applications, but the negative impedance may cause system instability. Actually the impedance interaction is much different between forward power flow and reversed power flow, which will introduce more uncertainty to the system...... stability. This paper proposes a control method for the constant power controlled converter in cascaded system, and consequently it can change the negative impedance of constant power converter into resistive impedance, which will improve the cascaded system stability, as well as merge the impedance...... difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  6. High-power arrays of quantum cascade laser master-oscillator power-amplifiers.

    Science.gov (United States)

    Rauter, Patrick; Menzel, Stefan; Goyal, Anish K; Wang, Christine A; Sanchez, Antonio; Turner, George; Capasso, Federico

    2013-02-25

    We report on multi-wavelength arrays of master-oscillator power-amplifier quantum cascade lasers operating at wavelengths between 9.2 and 9.8 μm. All elements of the high-performance array feature longitudinal (spectral) as well as transverse single-mode emission at peak powers between 2.7 and 10 W at room temperature. The performance of two arrays that are based on different seed-section designs is thoroughly studied and compared. High output power and excellent beam quality render the arrays highly suitable for stand-off spectroscopy applications.

  7. Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing

    Science.gov (United States)

    Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András

    2017-02-01

    Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.

  8. Tunable laser applications

    CERN Document Server

    Duarte, FJ

    2008-01-01

    Introduction F. J. Duarte Spectroscopic Applications of Tunable Optical Parametric Oscillators B. J. Orr, R. T. White, and Y. He Solid-State Dye Lasers Costela, I. García-Moreno, and R. Sastre Tunable Lasers Based on Dye-Doped Polymer Gain Media Incorporating Homogeneous Distributions of Functional Nanoparticles F. J. Duarte and R. O. James Broadly Tunable External-Cavity Semiconductor Lasers F. J. Duarte Tunable Fiber Lasers T. M. Shay and F. J. Duarte Fiber Laser Overview and Medical Applications

  9. Sensitivity of heterointerfaces on emission wavelength of quantum cascade lasers

    Science.gov (United States)

    Wang, C. A.; Schwarz, B.; Siriani, D. F.; Connors, M. K.; Missaggia, L. J.; Calawa, D. R.; McNulty, D.; Akey, A.; Zheng, M. C.; Donnelly, J. P.; Mansuripur, T. S.; Capasso, F.

    2017-04-01

    The measured emission wavelengths of AlInAs/GaInAs/InP quantum cascade lasers (QCLs) grown by metal organic vapor phase epitaxy (MOVPE) have been reported to be 0.5-1 μm longer than the designed QCL wavelength. This work clarifies the origin of the red-shifted wavelength. It was found that AlInAs/GaInAs heterointerfaces are compositionally graded over 2.5-4.5 nm, and indium accumulates at the AlInAs-to-GaInAs interface. Thus, the as-grown QCLs are far from the ideal abrupt interfaces used in QCL modeling. When graded layers are incorporated in QCL band structure and wavefunction calculations, the emission wavelengths are red shifted. Furthermore, we demonstrate that QCLs with graded interfaces can be designed without compromising performance and show greatly improved correlation between designed and measured emission wavelength. QCLs were designed for emission between 7.5 and 8.5 μm. These structures were grown and wet-etched ridge devices were fabricated. The QCLs exhibit room temperature peak powers exceeding 900 mW and pulsed efficiencies of 8 to 10%.

  10. Laser Applications in Orthodontics

    Science.gov (United States)

    Heidari, Somayeh; Torkan, Sepideh

    2013-01-01

    A laser is a collimated single wavelength of light which delivers a concentrated source of energy. Soon after different types of lasers were invented, investigators began to examine the effects of different wavelengths of laser energy on oral tissues, routine dental procedures and experimental applications. Orthodontists, along with other specialist in different fields of dentistry, can now benefit from several different advantages that lasers provide during the treatment process, from the beginning of the treatment, when separators are placed, to the time of resin residues removal from the tooth surface at the end of orthodontic treatment. This article outlines some of the most common usages of laser beam in orthodontics and also provides a comparison between laser and other conventional method that were the standard of care prior to the advent of laser in this field. PMID:25606324

  11. Towards nanowire-based terahertz quantum cascade lasers: prospects and technological challenges

    Science.gov (United States)

    Krall, Michael; Brandstetter, Martin; Deutsch, Christoph; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried; Unterrainer, Karl

    2013-03-01

    We present recent work towards the realization of a nanowire-based terahertz quantum cascade laser. Nanowires offer an additional quantum mechanical confinement of electrons in the plane of a two-dimensional quantum cascade structure. The additional quantization can greatly increase the lifetimes of intersubband transitions and therefore increase the optical gain and also the maximum operating temperature of terahertz quantum cascade lasers. We outline a fabrication process that is fully scalable from nanowire to micropillar devices and present measurements of micropillar arrays in a double metal waveguide. The results are very promising and also show the main technological challenges for realizing nanowire-based devices.

  12. Laser ablation principles and applications

    CERN Document Server

    1994-01-01

    Laser Ablation provides a broad picture of the current understanding of laser ablation and its many applications, from the views of key contributors to the field. Discussed are in detail the electronic processes in laser ablation of semiconductors and insulators, the post-ionization of laser-desorbed biomolecules, Fourier-transform mass spectroscopy, the interaction of laser radiation with organic polymers, laser ablation and optical surface damage, laser desorption/ablation with laser detection, and laser ablation of superconducting thin films.

  13. Efficient Dielectric Metasurface Collimating Lenses for Mid-Infrared Quantum Cascade Lasers

    CERN Document Server

    Arbabi, Amir; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-01-01

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 $\\mu$m distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0...

  14. Cascaded acceleration of proton beams in ultrashort laser-irradiated microtubes

    Science.gov (United States)

    Wang, H. C.; Weng, S. M.; Murakami, M.; Sheng, Z. M.; Chen, M.; Zhao, Q.; Zhang, J.

    2017-09-01

    A cascaded ion acceleration scheme is proposed by use of ultrashort laser-irradiated microtubes. When the electrons of a microtube are blown away by intense laser pulses, strong charge-separation electric fields are formed in the microtube along both the axial and radial directions. By controlling the time delay between the laser pulses and a pre-accelerated proton beam injected along the microtube axis, we demonstrate that this proton beam can be further accelerated by the transient axial electric field in the laser-irradiated microtube. Moreover, the collimation of the injected proton beam can be enhanced by the inward radial electric field. Numerical simulations show that this cascaded ion acceleration scheme works efficiently even at non-relativistic laser intensities, and it can be applied to injected proton beams in the energy range from 1 to 100 MeV. Therefore, it is particularly suitable for cascading acceleration of protons to higher energy.

  15. Development of a Quantum Cascade Laser-Based Detector for Ammonia and Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Zahniser, Mark S.; Nelson, David D.; McManus, J. Barry; Shorter, Joanne H.; Herndon, Scott C.; Jimenez, Rodrigo

    2005-12-31

    We have developed a compact, robust, atmospheric trace gas detector based on mid-infrared absorption spectroscopy using pulsed quantum cascade (QC) lasers. The spectrometer is suitable for airborne measurements of ammonia, nitric acid, formaldehyde, formic acid, methane, nitrous oxide, carbon monoxide, nitrogen dioxide and other gases that have line-resolved absorption spectra in the mid-infrared spectral region. The QC laser light source operates near room temperature with thermal electric cooling instead of liquid nitrogen which has been previously required for semiconductor lasers in the mid-infrared spectral region. The QC lasers have sufficient output power so that thermal electric cooled detectors may be used in many applications with lower precision requirements. The instrument developed in this program has been used in several field campaigns from both the Aerodyne Mobile Laboratory and from the NOAA WP3 aircraft. The Phase II program has resulted in more than 10 archival publications describing the technology and its applications. Over 12 instruments based on this design have been sold to research groups in Europe and the United States making the program both a commercial as well as a technological success. Anticipated Benefits The development of a sensitive, cryogen-free, mid-infrared absorption method for atmospheric trace gas detection will have wide benefits for atmospheric and environmental research and broader potential commercial applications in areas such as medical diagnostic and industrial process monitoring of gaseous compounds. Examples include air pollution monitoring, breath analysis, combustion exhaust diagnostics, and plasma diagnostics for semi-conductor fabrication. The substitution of near-room temperature QC lasers for cryogenic lead salt TDLs and the resulting simplifications in instrument design and operation will greatly expand the range of applications.

  16. Ionization-induced laser-driven QED cascade in noble gases

    Science.gov (United States)

    Artemenko, I. I.; Kostyukov, I. Yu.

    2017-09-01

    A formula for the ionization rate in an extremely intense electromagnetic field is proposed and used for numerical study of QED cascades in noble gases in the field of two counterpropagating laser pulses. It is shown that the number of the electron-positron pairs produced in the cascade increases with the atomic number of the gas, where the gas density is taken to be inversely proportional to the atomic number. While most of the electrons produced in the laser pulse front are expelled by the ponderomotive force from the region occupied by the strong laser field, there is a small portion of electrons staying in the laser field for a long time until the instance when the laser field is strong enough for cascading. This mechanism is relevant for all gases. For high-Z gases there is an additional mechanism associated with the ionization of inner shells at the instance when the laser field is strong enough for cascading. The role of both mechanisms for cascade initiation is revealed.

  17. High-resolution heterodyne spectroscopy using a tunable quantum cascade laser around 3.5 THz

    NARCIS (Netherlands)

    Ren, Y.; Hovenier, J.N.; Higgins, R.; Gao, J.R.; Klapwijk, T.M.; Shi, S.C.; Klein, B.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2011-01-01

    A frequency tunable terahertz heterodyne spectrometer, based on a third-order distributed feedback quantum cascade laser as a local oscillator, has been demonstrated by measuring molecular spectral lines of methanol (CH3OH) gas at 3.5 THz. By varying the bias voltage of the laser, we achieved a

  18. Laser absorption spectroscopy using lead salt and quantum cascade tunable lasers

    Science.gov (United States)

    Namjou-Khales, Khosrow

    A new class of analytic instruments based on the detection of chemical species through their spectroscopic absorption 'fingerprint' is emerging based on the use of tunable semiconductor lasers as the excitation source. Advantages of this approach include compact device size, in-line measurement capability, and large signal-bandwidth product. To realize these advantages will require the marriage of laser devices with broad tunability in the infrared spectral range with sophisticated signal processing techniques. Currently, commercial devices based on short wavelength telecommunications type lasers exist but there is potential for much more versatile instruments based on longer wavelength operation. This thesis is divided into two parts. In the first part I present a theoretical analysis and experimental characterization of frequency and wavelength modulation spectroscopy using long wavelength infrared tunable lasers. The experimental measurements were carried out using commercially available lead salt lasers and excellent agreement is found between theoretically predicted performance and experimental verification. The lead salt laser has several important drawbacks as a source in practical instrumentation. In the second part of the thesis I report on the use of the quantum cascade (QC) laser for use in sensitive absorption spectroscopy. The QC laser is a new type of tunable device developed at Bell Laboratories. It features broad infrared tunability, single mode distributed feedback operation, and near room temperature lasing. Using the modulation techniques developed originally for the lead salt lasers, the QC laser was used to detect Nsb2O and other small molecules with absorption features near 8 mum wavelength. The noise equivalent absorption for our measurements was 5× 10sp{-5}/sqrt{Hz} which corresponds to a detection limit of ˜0.25 ppm-m/sqrt{Hz} for Nsb2O. The QC laser sensitivity was found to be limited by excess amplitude modulation in the detection

  19. Type-I QW cascade diode lasers for spectral region above 3 μm

    Science.gov (United States)

    Shterengas, L.; Hosoda, T.; Wang, M.; Feng, T.; Kipshidze, G.; Belenky, G.

    2016-03-01

    Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in spectral region from 3.1 to 3.3 μm. The experiment showed that the increase of the number of cascades from two (previously used in record cascade 3 μm emitters) to three led to critical enhancement of the differential gain and reduction of the threshold current density of λ > 3 μm lasers. Light p-doping of the AlGaAsSb graded section did not introduce extra optical loss but aided hole transport as required for realization of the efficient multi-stage cascade pumping scheme. Corresponding coated three-stage devices with ~100-μm-wide aperture and 3-mm-long cavity demonstrated CW output power of 500 mW near 3.18 μm at 17 °C - more than twofold increase as compared to previous state-of-the-art diode lasers emitting only 200 mW. Three-stage lasers with quantum wells designed to emit in the middle of methane absorption band near 3.25 μm demonstrated record output power levels above 350 mW - nearly threefold improvement over previous non-cascade state-of-the-art diodes. Utilization of the different quantum wells in cascade laser heterostructure was demonstrated to yield wide gain lasers as often desired for tunable laser spectroscopy. Two step etching was applied in effort of simultaneous minimization of both internal optical loss and the lateral current spreading in narrow ridge lasers.

  20. Laser applications in surgery.

    Science.gov (United States)

    Azadgoli, Beina; Baker, Regina Y

    2016-12-01

    In modern medicine, lasers are increasingly utilized for treatment of a variety of pathologies as interest in less invasive treatment modalities intensifies. The physics behind lasers allows the same basic principles to be applied to a multitude of tissue types using slight modifications of the system. Multiple laser systems have been studied within each field of medicine. The term "laser" was combined with "surgery," "ablation," "lithotripsy," "cancer treatment," "tumor ablation," "dermatology," "skin rejuvenation," "lipolysis," "cardiology," "atrial fibrillation (AF)," and "epilepsy" during separate searches in the PubMed database. Original articles that studied the application of laser energy for these conditions were reviewed and included. A review of laser therapy is presented. Laser energy can be safely and effectively used for lithotripsy, for the treatment of various types of cancer, for a multitude of cosmetic and reconstructive procedures, and for the ablation of abnormal conductive pathways. For each of these conditions, management with lasers is comparable to, and potentially superior to, management with more traditional methods.

  1. Photo-generated metamaterials induce modulation of CW terahertz quantum cascade lasers

    Science.gov (United States)

    Mezzapesa, Francesco P.; Columbo, Lorenzo L.; Rizza, Carlo; Brambilla, Massimo; Ciattoni, Alessardro; Dabbicco, Maurizio; Vitiello, Miriam S.; Scamarcio, Gaetano

    2015-11-01

    Periodic patterns of photo-excited carriers on a semiconductor surface profoundly modifies its effective permittivity, creating a stationary all-optical quasi-metallic metamaterial. Intriguingly, one can tailor its artificial birefringence to modulate with unprecedented degrees of freedom both the amplitude and phase of a quantum cascade laser (QCL) subject to optical feedback from such an anisotropic reflector. Here, we conceive and devise a reconfigurable photo-designed Terahertz (THz) modulator and exploit it in a proof-of-concept experiment to control the emission properties of THz QCLs. Photo-exciting sub-wavelength metastructures on silicon, we induce polarization-dependent changes in the intra-cavity THz field, that can be probed by monitoring the voltage across the QCL terminals. This inherently flexible approach promises groundbreaking impact on THz photonics applications, including THz phase modulators, fast switches, and active hyperbolic media.

  2. Laser applications in neurosurgery

    Science.gov (United States)

    Cerullo, Leonard J.

    1985-09-01

    The "false start" of the laser in neurosurgery should not be misconstrued as a denial of the inherent advantages of precision and gentleness in dealing with neural tissue. Rather, early investigators were frustrated by unrealistic expectations, cumbersome equipment, and a general ignorance of microtechnique. By the early 70s, microneurosurgery was well established, surgical laser equipment for free hand and microlinked application had been developed, and a more realistic view of the limitations of the laser had been established. Consequently, the late 70s really heralded the renaissance of the laser in neurosurgery. Since then, there has been an overwhelming acceptance of the tool in a variety of clinical situations, broadly categorized in five groups. 1)|Perhaps the most generally accepted area is in the removal of extra-axial tumors of the brain and spinal cord. These tumors, benign by histology but treacherous by location, do not present until a significant amount of neurological compensation has already occurred. The application of additional trauma to the neural tissue, whether by further tumor growth or surgical manipulation, frequently results in irreversible damage. Here, the ability of the laser to vaporize tissue, in a fairly hemostatic fashion, without mechanical or thermal damage to sensitive surrounding tissues, is essential. 2)|The ability to incise delicate neural tissue with minimal spread of thermal destruction to adjacent functioning tissue makes the laser the ideal instrument when tumors deep under the surface are encountered in the brain or spinal cord. Thus, the second group of applications is in the transgression of normal neural structures to arrive at deeper pathological tissue. 3)|The third area of benefit for the laser in neurosurgery has been in the performance of neuroablative procedures, calling for deliberate destruction of functioning neural tissue in a controlled fashion. Again, the precision and shape confinement of the destructive

  3. A sulfur hexafluoride sensor using quantum cascade and CO2 laser-based photoacoustic spectroscopy.

    Science.gov (United States)

    Rocha, Mila; Sthel, Marcelo; Lima, Guilherme; da Silva, Marcelo; Schramm, Delson; Miklós, András; Vargas, Helion

    2010-01-01

    The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m(2). This work compares two photoacoustic spectrometers, one coupled to a CO(2) laser and another one coupled to a Quantum Cascade (QC) laser, for the detection of SF(6). The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO(2) laser and 50 ppbv for quantum cascade laser were obtained.

  4. Laser Ablation for Medical Applications

    Science.gov (United States)

    Hayashi, Ken-Ichi

    Medical applications of laser are measurement, laser surgery, in-situ monitoring, and processing of medical devices. In this paper, author briefly reviews the trends of medical applications, describes some new applications, and then discuss about the future trends and problems of medical applications. At present, the domestic market of laser equipment for medical applications is nearly 1/10 of that for industrial applications, which has registered significant growth continuously. Laser surgery as a minimum invasive surgery under arthroscope is expected to decrease the pain of patients. Precise processing such as cutting and welding is suitable for manufacturing medical devices. Pulsed laser deposition has been successfully applied to the thin film coating. The corneal refractive surgery by ArF excimer laser has been widely accepted for its highly safe operation. Laser ablation for retinal implant in the visual prosthesis is one of the promising applications of laser ablation in medicine. New applications with femtosecond laser are expected in the near future.

  5. Cascade Type-I Quantum Well GaSb-Based Diode Lasers

    Directory of Open Access Journals (Sweden)

    Leon Shterengas

    2016-05-01

    Full Text Available Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in a spectral region from 1.9 to 3.3 μm. Carrier recycling between quantum well gain stages was realized using band-to-band tunneling in GaSb/AlSb/InAs heterostructure complemented with optimized electron and hole injector regions. Coated devices with an ~100-μm-wide aperture and a 3-mm-long cavity demonstrated continuous wave (CW output power of 1.96 W near 2 μm, 980 mW near 3 μm, 500 mW near 3.18 μm, and 360 mW near 3.25 μm at 17–20 °C—a nearly or more than twofold increase compared to previous state-of-the-art diode lasers. The utilization of the different quantum wells in the cascade laser heterostructure was demonstrated to yield wide gain lasers, as often desired for tunable laser spectroscopy. Double-step etching was utilized to minimize both the internal optical loss and the lateral current spreading penalties in narrow-ridge lasers. Narrow-ridge cascade diode lasers operate in a CW regime with ~100 mW of output power near and above 3 μm and above 150 mW near 2 μm.

  6. Enhanced light output power of quantum cascade lasers from a tilted front facet.

    Science.gov (United States)

    Ahn, Sangil; Schwarzer, Clemens; Zederbauer, Tobias; Detz, Hermann; Andrews, Aaron M; Schrenk, Werner; Strasser, Gottfried

    2013-07-01

    We present a technique for enhancing the light output power of quantum cascade lasers (QCLs) by tilting of the front facet, which leads to a change of the modal reflectivity, resulting in an asymmetric light intensity distribution along the laser cavity. This asymmetry provides most of the light being emitted through one facet of the laser. An experimental study of threshold current, slope efficiency and light output power as a function of the front facet angles were performed and compared to conventional QCLs. The lasers with a front facet angle of 8° shows a 20% improved power output from the front facet.

  7. Infrared absorption nano-spectroscopy using sample photoexpansion induced by tunable quantum cascade lasers.

    Science.gov (United States)

    Lu, Feng; Belkin, Mikhail A

    2011-10-10

    We report a simple technique that allows obtaining mid-infrared absorption spectra with nanoscale spatial resolution under low-power illumination from tunable quantum cascade lasers. Light absorption is detected by measuring associated sample thermal expansion with an atomic force microscope. To detect minute thermal expansion we tune the repetition frequency of laser pulses in resonance with the mechanical frequency of the atomic force microscope cantilever. Spatial resolution of better than 50 nm is experimentally demonstrated.

  8. Beam and phase distributions of a terahertz quantum cascade wire laser

    NARCIS (Netherlands)

    Cui, M.; Hovenier, J.N.; Ren, Y.; Vercruyssen, N.; Gao, J.R.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2013-01-01

    We report on both measurements and simulations of the beam profile and wavefront of a single-mode, 3.5?THz quantum cascade wire laser, incorporating a lateral corrugated metal-metal waveguide, 3rd-order distributed feedback grating. The intrinsic wavefront was measured by using a Hartmann wavefront

  9. Thermal Management of Quantum Cascade Lasers in an individually Addressable Array Architecture

    Science.gov (United States)

    2016-02-08

    Thermal Management of Quantum Cascade Lasers in an Individually Addressable Monolithic Array Architecture Leo Missaggia, Christine Wang, Michael...regards to the design of the packaging architecture required to facilitate the CBC of emitter arrays containing large numbers of elements...characteristics of QCL device performance which make QCL array architectures thermally challenging. Among these are; 1. Relatively low electrical

  10. Frequency Stabilization of a Single Mode Terahertz Quantum Cascade Laser to the Kilohertz Level

    Science.gov (United States)

    2009-04-27

    Frequency stabilization of a single mode terahertz quantum cascade laser to the kilohertz level 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...primarily in a single-longitudinal mode (SLM) up to a bias voltage of 3.7 V and a multi-lodgitudinal mode ( MLM ) at higher voltages. It was mounted in a

  11. Thermal management of quantum cascade lasers in an individually addressable monolithic array architecture

    Science.gov (United States)

    Missaggia, Leo; Wang, Christine; Connors, Michael; Saar, Brian; Sanchez-Rubio, Antonio; Creedon, Kevin; Turner, George; Herzog, William

    2016-03-01

    There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9μm.

  12. 77 FR 73651 - Cascade Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2012-12-11

    ... No. 14464-000] Cascade Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for..., Cascade Energy Storage, LLC, filed an application for a preliminary permit, pursuant to section 4(f) of... Executive Officer, Cascade Energy Storage, LLC, 1210 W. Franklin Street, Ste. 2, Boise, Idaho 83702; phone...

  13. Single-mode quantum cascade lasers employing a candy-cane shaped monolithic coupled cavity

    Science.gov (United States)

    Liu, Peter Q.; Sladek, Kamil; Wang, Xiaojun; Fan, Jen-Yu; Gmachl, Claire F.

    2011-12-01

    We demonstrate single-mode quantum cascade lasers emitting at ˜4.5 μm by employing a monolithic "candy-cane" shaped coupled-cavity consisting of a straight section connecting at one end to a spiral section. The fabrication process is identical to those for simple Fabry-Perot-type ridge lasers. Continuously tunable single-mode emission across ˜8 cm-1 with side mode suppression ratio up to ˜25 dB and a single-mode operating current range of more than 70% above the threshold current is achieved when the lasers are operated in pulsed-mode from 80 K to 155 K.

  14. Pyrometry applications in laser machining

    Science.gov (United States)

    Smurov, Igor

    2001-01-01

    Special techniques of non-contact optical diagnostics under actual industrial conditions is required for accurate temperature monitoring and control in a wide range of laser applications. The set of pyrometers was developed and applied for surface temperature monitoring in pulsed periodic Nd:YAG laser welding and surface treatment, deep penetration welding by CO2 and Nd:YAG lasers, and electron beam; laser assisted machining; laser cladding, etc.

  15. Quantum cascade lasers transfer-printed on silicon-on-sapphire

    Science.gov (United States)

    Jung, Seungyong; Kirch, Jeremy; Kim, Jae Hyun; Mawst, Luke J.; Botez, Dan; Belkin, Mikhail A.

    2017-11-01

    We demonstrate coupling of the laser mode into a passive waveguide by transfer-printing fully processed mid-infrared quantum cascade lasers onto a silicon-on-sapphire platform. The laser waveguide mode is coupled into a silicon waveguide via an adiabatic taper. The experimentally achieved coupling efficiency of the taper is estimated to be ˜10%, and theoretical calculations show that coupling efficiency over 75% is achievable by reducing the adhesive layer thickness to below 100 nm. Light coupling to silicon waveguides is confirmed by images taken at the output facet of a 3-mm-long passive Si waveguide with a mid-infrared camera. Our technique enables the development of heterogeneous photonic systems integrated with a wide range of fully processed semiconductor laser devices, including buried-heterostructure lasers, which was not previously possible.

  16. Development of Quantum Cascade Lasers with Novel Active Regions and Integrated Nano-Antennas

    Science.gov (United States)

    Dey, Dibyendu

    Quantum Cascade Laser (QCL), invented in 1994, has led to path-breaking improvements in room-temperature operation in mid and long wave infrared, and has been used in gas and chemical sensing, bio-imaging, free-space communications and many other military applications. One of the major operational drawbacks of standard QCL is added phonon relaxation in the injector region leading to generation of excess heat. The first part of my thesis focuses on developing a novel injectorless QCL (I-QCL) which circumvents this problem. The fabricated laser was both electrically and optically tested and compared with two types of standard QCLs---one developed in our laboratory and another provided by MIT Lincoln Laboratory. Voltage defect is a key parameter used to quantify excess heat generated in a QCL. We were able to measure a record low voltage defect of ˜ 57 meV at 77 K using the I-QCL we have developed. The effect of injectors on thermal performance of QCL was further analyzed through time-resolved spectral analysis. Next, we focused on developing a composite material based plasmonic antenna integrated QCL. The device was capable of squeezing the optical mode to ˜ 100 nm which is 60 times smaller than the operating wavelength (˜ 6 um). Such mode confinement can overcome the primary drawback in a mid-IR bio-sensor where the dimensional mismatch between long wavelengths (order of microns) and tiny probed molecules (˜ few nanometers) makes probe-particle interaction strength extremely weak. An apertureless near-field scanning optical microscope (a-NSOM) was built to measure the antenna near-field characteristic. We further worked on measuring the optical force generated near the antenna "hotspot" due to high electric field gradient. We then worked on understanding the coupling between antenna plasmonic modes and the laser cavity mode. This unusual coupling has been explained based on optical feedback effect. The final part of my research focused on delivering the bio

  17. Watt-Level Continuous-Wave Emission from a Bi-Functional Quantum Cascade Laser/Detector

    Science.gov (United States)

    2017-04-18

    Faist, J. Quantum -cascade-laser structures as photodetectors. Applied Physics Letters 2002, 81, 2683. (17) Gendron, L.; Carras, M.; Huynh, A.; Ortiz, V...Koeniguer, C.; Berger, V. Quantum cascade photodetector. Applied Physics Letters 2004, 85, 2824. (18) Reininger, P.; Zederbauer, T.; Schwarz, B...Detz, H.; MacFarland, D.; Andrews, A. M.; Schrenk, W.; Strasser, G. InAs/AlAsSb based quantum cascade detector. Applied Physics Letters 2015, 107

  18. Diode laser applications in urology

    Science.gov (United States)

    Sam, Richard C.; Esch, Victor C.

    1995-05-01

    Diode lasers are air-cooled, efficient, compact devices which have the potential of very low cost when produced in quantity. The characteristics of diode lasers are discussed. Their applications in interstitial thermal treatment of the prostate, and laser ablation of prostate tissues, will be presented.

  19. Mode-locked pulses from mid-infrared quantum cascade lasers.

    Science.gov (United States)

    Wang, Christine Y; Kuznetsova, Lyuba; Gkortsas, V M; Diehl, L; Kärtner, F X; Belkin, M A; Belyanin, A; Li, X; Ham, D; Schneider, H; Grant, P; Song, C Y; Haffouz, S; Wasilewski, Z R; Liu, H C; Capasso, Federico

    2009-07-20

    In this study, we report the unequivocal demonstration of midinfrared mode-locked pulses from quantum cascade lasers. The train of short pulses was generated by actively modulating the current and hence the gain of an edge-emitting quantum cascade laser (QCL). Pulses with duration of about 3 ps at full-width-at-half-maxima and energy of 0.5 pJ were characterized using a second-order interferometric autocorrelation technique based on a nonlinear quantum well infrared photodetector. The mode-locking dynamics in the QCLs was modeled based on the Maxwell-Bloch equations in an open two-level system. Our model reproduces the overall shape of the measured autocorrelation traces and predicts that the short pulses are accompanied by substantial wings as a result of strong spatial hole burning. The range of parameters where short mode-locked pulses can be formed is found.

  20. Far-infrared quantum cascade lasers operating in AlAs phonon Reststrahlen band

    CERN Document Server

    Ohtani, K; Süess, M J; Faist, J; Andrews, A M; Zederbauer, T; Detz, H; Schrenk, W; Strasser, G

    2016-01-01

    We report on the operation of a double metal waveguide far-infrared quantum cascade laser emitting at 28 $\\mu$m, corresponding to the AlAs-like phonon Reststrahlen band. To avoid absorption by AlAs-like optical phonons, the Al-free group-V alloy GaAs$_{0.51}$Sb$_{0.49}$ is used as a barrier layer in the bound-to-continuum based active region. Lasing occurs at a wavelength of 28.3 $\\mu$m, which is the longest wavelength among the quantum cascade lasers operating from mid-infrared to far-infrared. The threshold current density at 50 K is 5.5 kA/cm$^{2}$ and maximum operation temperature is 175 K. We also discuss the feasibility that operation wavelength cover the whole spectral range bridging between mid-infrared and terahertz by choosing suited group III-V materials.

  1. Development of a Multi-Objective Evolutionary Algorithm for Strain-Enhanced Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    David Mueller

    2016-07-01

    Full Text Available An automated design approach using an evolutionary algorithm for the development of quantum cascade lasers (QCLs is presented. Our algorithmic approach merges computational intelligence techniques with the physics of device structures, representing a design methodology that reduces experimental effort and costs. The algorithm was developed to produce QCLs with a three-well, diagonal-transition active region and a five-well injector region. Specifically, we applied this technique to Al x Ga 1 - x As/In y Ga 1 - y As strained active region designs. The algorithmic approach is a non-dominated sorting method using four aggregate objectives: target wavelength, population inversion via longitudinal-optical (LO phonon extraction, injector level coupling, and an optical gain metric. Analysis indicates that the most plausible device candidates are a result of the optical gain metric and a total aggregate of all objectives. However, design limitations exist in many of the resulting candidates, indicating need for additional objective criteria and parameter limits to improve the application of this and other evolutionary algorithm methods.

  2. Fast quantification of bovine milk proteins employing external cavity-quantum cascade laser spectroscopy.

    Science.gov (United States)

    Schwaighofer, Andreas; Kuligowski, Julia; Quintás, Guillermo; Mayer, Helmut K; Lendl, Bernhard

    2018-06-30

    Analysis of proteins in bovine milk is usually tackled by time-consuming analytical approaches involving wet-chemical, multi-step sample clean-up procedures. The use of external cavity-quantum cascade laser (EC-QCL) based IR spectroscopy was evaluated as an alternative screening tool for direct and simultaneous quantification of individual proteins (i.e. casein and β-lactoglobulin) and total protein content in commercial bovine milk samples. Mid-IR spectra of protein standard mixtures were used for building partial least squares (PLS) regression models. A sample set comprising different milk types (pasteurized; differently processed extended shelf life, ESL; ultra-high temperature, UHT) was analysed and results were compared to reference methods. Concentration values of the QCL-IR spectroscopy approach obtained within several minutes are in good agreement with reference methods involving multiple sample preparation steps. The potential application as a fast screening method for estimating the heat load applied to liquid milk is demonstrated. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Portable open-path chemical sensor using a quantum cascade laser

    Science.gov (United States)

    Corrigan, Paul; Lwin, Maung; Huntley, Reuven; Chhabra, Amandeep; Moshary, Fred; Gross, Barry; Ahmed, Samir

    2009-05-01

    Remote sensing of enemy installations or their movements by trace gas detection is a critical but challenging military objective. Open path measurements over ranges of a few meters to many kilometers with sensitivity in the parts per million or billion regime are crucial in anticipating the presence of a threat. Previous approaches to detect ground level chemical plumes, explosive constituents, or combustion have relied on low-resolution, short range Fourier transform infrared spectrometer (FTIR), or low-sensitivity near-infrared differential optical absorption spectroscopy (DOAS). As mid-infrared quantum cascade laser (QCL) sources have improved in cost and performance, systems based on QCL's that can be tailored to monitor multiple chemical species in real time are becoming a viable alternative. We present the design of a portable, high-resolution, multi-kilometer open path trace gas sensor based on QCL technology. Using a tunable (1045-1047cm-1) QCL, a modeled atmosphere and link-budget analysis with commercial component specifications, we show that with this approach, accuracy in parts per billion ozone or ammonia can be obtained in seconds at path lengths up to 10 km. We have assembled an open-path QCL sensor based on this theoretical approach at City College of New York, and we present preliminary results demonstrating the potential of QCLs in open-path sensing applications.

  4. pH titration monitored by quantum cascade laser-based vibrational circular dichroism.

    Science.gov (United States)

    Rüther, Anja; Pfeifer, Marcel; Lórenz-Fonfría, Víctor A; Lüdeke, Steffen

    2014-04-10

    Vibrational circular dichroism (VCD) spectra of aqueous solutions of proline were recorded in the course of titrations from basic to acidic pH using a spectrometer equipped with a quantum cascade laser (QCL) as an infrared light source in the spectral range from 1320 to 1220 cm(-1). The pH-dependent spectra were analyzed by singular value decomposition and global fitting of a two-pK Henderson-Hasselbalch model. The analysis delivered relative fractions of the three different protonation species. Their agreement with the relative fractions obtained from performing the same analysis on pH-dependent Fourier transform infrared (FT-IR) and QCL-IR spectra validates the quantitative results from QCL-VCD. Global fitting of the pH-dependent VCD spectra of L-proline allowed for extraction of pure spectra corresponding to anionic, zwitterionic, and cationic L-proline. From a static experiment, only pure spectra of the zwitterion would be accessible in a straightforward way. A comparison to VCD spectra calculated for all three species led to assignment of vibrational modes that are characteristic for the respective protonation states. The study demonstrates the applicability of QCL-VCD both for quantitative evaluation and for qualitative interpretation of dynamic processes in aqueous solutions.

  5. Quantum cascade laser-based sensor system for nitric oxide detection

    Science.gov (United States)

    Tittel, Frank K.; Allred, James J.; Cao, Yingchun; Sanchez, Nancy P.; Ren, Wei; Jiang, Wenzhe; Jiang, Dongfang; Griffin, Robert J.

    2015-01-01

    Sensitive detection of nitric oxide (NO) at ppbv concentration levels has an important impact in diverse fields of applications including environmental monitoring, industrial process control and medical diagnostics. For example, NO can be used as a biomarker of asthma and inflammatory lung diseases such as chronic obstructive pulmonary disease. Trace gas sensor systems capable of high sensitivity require the targeting of strong rotational-vibrational bands in the mid-IR spectral range. These bands are accessible using state-of-the-art high heat load (HHL) packaged, continuous wave (CW), distributed feedback (DFB) quantum cascade lasers (QCLs). Quartz-enhanced photoacoustic spectroscopy (QEPAS) permits the design of fast, sensitive, selective, and compact sensor systems. A QEPAS sensor was developed employing a room-temperature CW DFB-QCL emitting at 5.26 μm with an optical excitation power of 60 mW. High sensitivity is achieved by targeting a NO absorption line at 1900.08 cm-1 free of interference by H2O and CO2. The minimum detection limit of the sensor is 7.5 and 1 ppbv of NO with 1and 100 second averaging time respectively . The sensitivity of the sensor system is sufficient for detecting NO in exhaled human breath, with typical concentration levels ranging from 24.0 ppbv to 54.0 ppbv.

  6. Nanoscopic voltage distribution of operating cascade laser devices in cryogenic temperature.

    Science.gov (United States)

    Dhar, R S; Ban, D

    2016-06-01

    A nanoscopic exploratory measurement technique to measure voltage distribution across an operating semiconductor device in cryogenic temperature has been developed and established. The cross-section surface of the terahertz (THz) quantum cascade laser (QCL) has been measured that resolves the voltage distribution at nanometer scales. The electric field dissemination across the active region of the device has been attained under the device's lasing conditions at cryogenic temperature of 77 K. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  7. Laser Apparatus with Cascade of Nonlinear Frequency Mixers

    DEFF Research Database (Denmark)

    2015-01-01

    -mixed beam comprising at least an output frequency component having at least said third frequency a dispersive element configured to adjustably change an optical path length of the intermediate beam path of the first frequency-mixed beam so as to compensate for dispersion along at least the intermediate beam...... frequency wherein the laser apparatus is further configured to direct the resulting first frequency-mixed beam along an intermediate beam path to a subsequent nonlinear frequency mixer chosen from the first and another one of the one or more nonlinear frequency mixers, resulting in a second frequency...... path....

  8. Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

    Science.gov (United States)

    Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

    2013-11-04

    We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

  9. Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas

    Directory of Open Access Journals (Sweden)

    Pietro Mario Lugarà

    2009-04-01

    Full Text Available We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 seconds time constant and 4 mW laser power. Measurements in ambient air will require water vapour filters.

  10. Intra-pulse beam steering in a mid-infrared quantum cascade laser

    OpenAIRE

    Pruszy?ska-Karbownik, Emilia; Regi?ski, Kazimierz; Karbownik, Piotr; Mroziewicz, Bohdan

    2014-01-01

    The intra-pulse measurements of the beam steering in an AlGaAs/GaAs quantum cascade laser are presented in this paper. The experimental results are explained by a two-mode theoretical model. The near field of the laser radiation is calculated according to the effective index method and transposed to the far field numerically according to Huygens principle. The maximal observed value of deflection of the beam has been found to be \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{w...

  11. Mid-Infrared Quantum-Dot Quantum Cascade Laser: A Theoretical Feasibility Study

    Directory of Open Access Journals (Sweden)

    Stephan Michael

    2016-05-01

    Full Text Available In the framework of a microscopic model for intersubband gain from electrically pumped quantum-dot structures we investigate electrically pumped quantum-dots as active material for a mid-infrared quantum cascade laser. Our previous calculations have indicated that these structures could operate with reduced threshold current densities while also achieving a modal gain comparable to that of quantum well active materials. Here, we study the influence of two important quantum-dot material parameters, namely inhomogeneous broadening and quantum-dot sheet density, on the performance of a proposed quantum cascade laser design. In terms of achieving a positive modal net gain, a high quantum-dot density can compensate for moderately high inhomogeneous broadening, but at a cost of increased threshold current density. However, by minimizing quantum-dot density with presently achievable inhomogeneous broadening and total losses, significantly lower threshold densities than those reported in quantum-well quantum-cascade lasers are predicted by our theory.

  12. Development of Novel Mid-Infrared Spectrometers Based on Quantum Cascade Lasers

    Science.gov (United States)

    Wang, Yin

    Sensitive detection of trace gas molecules has various important applications in environmental science, medical diagnostics and homeland security. The invention of quantum cascade lasers (QCLs) has triggered development of compact, efficient and highly sensitive mid-infrared (mid-IR) spectroscopic techniques. This dissertation is primarily focused on Faraday rotation spectroscopy (FRS) for detection of gas-phase radicals, and new methods to perform broadband, high-resolution mid-IR spectroscopy. The developed techniques allow the sensor to reach quantum limit in the real-world settings. The noise in traditional FRS systems is typically far above the quantum shot-noise due to the strong laser noise at its spectral base-band. Here, a method employing heterodyne-enhanced FRS (H-FRS) is developed. Through optical heterodyning, the signal is shifted from the low frequency to radio frequencies (RF), where the noise is strongly suppressed, allowing significant improvement of the signal-to-noise ratio. An experimental demonstration of H-FRS was performed using a distributed feedback QCL and a mercury-cadmium-telluride photodetector. The cryogen-free system exhibited the total noise of 3.7 times higher than the quantum shot-noise. The complex optical design of H-FRS limits its application only to laboratory conditions. To overcome this issue a dual modulation FRS method that requires much simpler set-up and is capable of even higher performance than H-FRS is proposed. A prototype was built as a robust transportable system and was delivered to Cleveland Clinic for the first, proof-of-principle isotopic studies of nitric oxide metabolism in human body. The total noise observed in this system is only two times higher than the quantum shot-noise. A laser testing system for optimizing QCL chips is developed. The system allows for automatic optical alignment and characterization of the QCL chips in an external cavity QCL configuration. Thus it significantly improves the data

  13. Simultaneous detection of atmospheric nitrous oxide and carbon monoxide using a quantum cascade laser

    Science.gov (United States)

    Khan, Amir; Sun, Kang; Miller, David J.; Zondlo, Mark A.

    2011-06-01

    We describe a non-intrusive, open-path, fast-response compact sensor for simultaneous measurements of nitrous-oxide (N2O) and carbon-monoxide (CO) primarily designed for UAV applications. N2O is the third most important anthropogenic greenhouse gas, but the spatial and temporal distributions of N2O emissions are poorly quantified. On the other hand, CO is an important tracer to distinguish between fossil fuel and biogenic sources. We use a 4.5 micron thermoelectrically-cooled, distributed feedback, continuous wave quantum cascade laser as a mid-infrared radiation source to scan CO and N2O transitions centered at 4538.9 nm and 4539.8 nm respectively. Detection was achieved by a thermo-electrically (TE) cooled 5 micron Indium-Phosphide (InSb) infrared detector. For the first time in this application, a compact cylindrical cell with a pattern configuration to minimize the sensor size with a pathlength of 10 meters (2.54 cm radius mirrors, 25 cm basepath). Wavelength modulation spectroscopy was employed to achieve high sensitivity detection. The detection limit of 10-5 fractional absorbance was achieved at a 10 sec. averaging time. This is equivalent to less than 1 ppbv of N2O and 2 ppbv of CO out of 320 ppbv and 200 ppbv ambient levels respectively. In summary we report a cryogen-free, consumable-free sensor that can operate with 10s W of electrical power and packaged in a small shoe-box size which is ideal for UAV or airborne applications.

  14. Ultrasensitive photoacoustic sensor based on quantum cascade laser spectroscopy.

    Science.gov (United States)

    Kumar, Deepak; Gautam, Surya; Kumar, Subodh; Gupta, Saurabh; Srivastava, Hari B; Thakur, Surya N; Sharma, Ramesh C

    2017-04-05

    The paper focuses on development of ultra-sonic detection system based on laser photoacoustic spectroscopic technique and processing of signal for detection of very low quantity chemicals, explosive materials, and mixtures of these hazardous molecules. The detection system has been developed for the first time with specially designed one side open photo-acoustic cell having high quality factor. Explosive and Hazardous materials like RDX, DNT, PETN, Gun Powder, TATP (Tri acetone tri-peroxide) and their simulants like Acetone were detected in 7 to 9μm wavelength band. Lock in amplifier electronic instrument was used for the detection of hazardous chemicals and mixture of explosives in very low quantity. Detection limit of the photoacoustic ultrasonic sensor was also carried out of powder, liquid and adsorbed on surfaces. Copyright © 2016. Published by Elsevier B.V.

  15. Ultrasensitive photoacoustic sensor based on quantum cascade laser spectroscopy

    Science.gov (United States)

    Kumar, Deepak; Gautam, Surya; Kumar, Subodh; Gupta, Saurabh; Srivastava, Hari B.; Thakur, Surya N.; Sharma, Ramesh C.

    2017-04-01

    The paper focuses on development of ultra-sonic detection system based on laser photoacoustic spectroscopic technique and processing of signal for detection of very low quantity chemicals, explosive materials, and mixtures of these hazardous molecules. The detection system has been developed for the first time with specially designed one side open photo-acoustic cell having high quality factor. Explosive and Hazardous materials like RDX, DNT, PETN, Gun Powder, TATP (Tri acetone tri-peroxide) and their simulants like Acetone were detected in 7 to 9 μm wavelength band. Lock in amplifier electronic instrument was used for the detection of hazardous chemicals and mixture of explosives in very low quantity. Detection limit of the photoacoustic ultrasonic sensor was also carried out of powder, liquid and adsorbed on surfaces.

  16. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading.

    Science.gov (United States)

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-01

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

  17. Numerical investigation of positive dihedral application conditions in compressor cascades

    Directory of Open Access Journals (Sweden)

    Detang Zeng

    2015-06-01

    Full Text Available This study attempts to make a contribution to the understanding of dihedral application conditions and their aerodynamic mechanisms. The present efforts have finished contrastive investigations on several dihedral blades to their corresponding straight ones with different geometric or aerodynamic conditions including aspect ratio, solidity, aerofoil turning angle, inlet boundary layer configuration and inlet Mach number. A dihedral with the angle between the suction side and the endwall to be obtuse, i.e., positive dihedral, is chosen. The result reveals the dihedral application conditions consist of aerofoil turning angle, inlet boundary layer, inlet Mach number and so on. The further analysis indicates: in a transonic cascade, two considerations are needed on the contrastive relationship between intensities of the two shocks, namely detached shock and passage shock, and the interaction of the shocks with the corner separation.

  18. Long-term reliability study and failure analysis of quantum cascade lasers

    Science.gov (United States)

    Xie, Feng; Nguyen, Hong-Ky; Leblanc, Herve; Hughes, Larry; Wang, Jie; Miller, Dean J.; Lascola, Kevin

    2017-02-01

    Here we present lifetime test results of 4 groups of quantum cascade lasers (QCL) under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 million device·hours, which is the largest QCL reliability study ever reported. The longest single device aging time was 46.5 thousand hours (without failure) in the room temperature test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Visual inspection of the laser facets of failed devices revealed an astonishing phenomenon, which has never been reported before, which manifested as a dark belt of an unknown substance appearing on facets. Although initially assumed to be contamination from the environment, failure analysis revealed that the dark substance is a thermally induced oxide of InP in the buried heterostructure semiinsulating layer. When the oxidized material starts to cover the core and blocks the light emission, it begins to cause the failure of QCLs in the accelerated test. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. With the activation energy, the mean time to failure of the quantum cascade lasers operating at a current density of 5 kA/cm2 and heat-sink temperature of 25°C is expected to be 809 thousand hours.

  19. Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H2S measurements in a petrochemical process gas stream

    OpenAIRE

    Moser, Harald; P?lz, Walter; Waclawek, Johannes Paul; Ofner, Johannes; Lendl, Bernhard

    2016-01-01

    The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8-?m continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H2S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH4) matrix of up to 1000?...

  20. Integration of Quantum Cascade Lasers and Passive Waveguides

    Science.gov (United States)

    2015-06-01

    other applications, in- tegrating the active gain material with the relevant pho- tonic elements monolithically on a common substrate re- quires...passivation technique shows promise toward enabling infrared pho- tonic integrated circuits and several compelling applica- tions such as monolithic beam...M. Giovannini, and J. Faist, IEEE J. Quantum Electron. 44, 36 (2008). 6A. Goyal, L. Diehl, C. Pfluegl, C. Wang, and M. Witinski, “Pho- tonic

  1. High performance quantum cascade lasers: Loss, beam stability, and gain engineering

    Science.gov (United States)

    Bouzi, Pierre Michel

    Quantum Cascade (QC) lasers are semiconductor devices emitting in the mid-infrared (3-30 micron) and terahertz (30-300 micron) regions of the electromagnetic spectrum. Since their first demonstration by Jerome Faist et. al. in 1994, they have evolved very quickly into high performance devices and given rise to many applications such as trace-gas sensing, medical diagnosis, free-space communication, and light detection and ranging (LIDAR). In this thesis, we investigate a further increase of the performance of QC devices and, through meticulous device modeling and characterizations, gain a deeper understanding of several of their unique characteristics, especially their carrier transport and lifetime, their characteristic temperature, their waveguide loss and modal gain, their leakage current, and their transverse mode profile. First, in our quest to achieve higher performance, we investigate the effect of growth asymmetries on device transport characteristics. This investigation stems from recent studies on the role of interface roughness on intersubband scattering and device performance. Through a symmetric active core design, we find that interface roughness and ionized impurity scattering induced by dopant migration play a significant role in carrier transport through the device. Understanding how interface roughness affects intersubband scattering, in turn, we engineer the gain in QC devices by placing monolayer barriers at specific locations within the device band structure. These strategically placed additional thin barrier layers introduce roughness scattering into the device active region, thereby selectively decreasing the lower laser state lifetime and increasing population inversion necessary for laser action. Preliminary measurement results from modified devices reveal a 50% decrease in the emission broadening compared to the control structures, which should lead to a two-fold increase in gain. A special class of so-called "strong coupling" QC lasers

  2. Ultra-bright GeV photon source via controlled electromagnetic cascades in laser-dipole waves

    Science.gov (United States)

    Gonoskov, Arkady; Bashinov, Alexey; Efimenko, Evgeny; Muraviev, Alexander; Kim, Arkady; Ilderton, Anton; Bastrakov, Sergey; Meyerov, Iosif; Marklund, Mattias; Sergeev, Alexander

    2017-10-01

    The prospect of achieving conditions for triggering strong-field QED phenomena at upcoming large-scale laser facilities raises a number of intriguing questions. What kind of new effects and interaction regimes can be accessed by basic QED phenomena? What are the minimal (optimal) requirements to trigger these effects and enter these regimes? How can we, from this, gain new fundamental knowledge or create important applications? The talk will concern the prospects of producing high fluxes of GeV photons by triggering a special type of self-sustaining cascade in the field of several colliding laser pulses that form a dipole wave. Apart from reaching the highest field strength for a given total power of laser pulses, the dipole wave enables anomalous radiative trapping that favors pair production and high-energy photon generation. An extensive theoretical analysis and 3D QED-PIC simulations indicate that the concept is feasible at upcoming large-scale laser facilities of 10 PW level and can provide an extraordinary intense source of GeV photons for novel experimental studies in nuclear and quark-nuclear physics.

  3. Importance of coherence in models of mid-infrared quantum cascade laser gain spectra

    Science.gov (United States)

    Cui, Yuzhang I.; Harter, Michael P.; Dikmelik, Yamac; Hoffman, Anthony J.

    2017-09-01

    We present a three-level model based on a density matrix to examine the influence of coherence and dephasing on the gain spectrum of mid-infrared quantum cascade lasers. The model is used to examine a quantum cascade active region with multiple optical transitions. We show how coherence can explain the origin of additional peaks in the gain spectrum. We also analyze the spectra calculated using the three-level model with a rate equation formalism to demonstrate the importance of considering interface roughness and limitations of the rate equation formalism. Specifically, we present how interface roughness influences the broadening and oscillator strength that are recovered using a rate equation analysis. The results of this work are important when considering the design of active regions with multiple optical transitions and could lead to devices with improved performance.

  4. Ultraviolet laser technology and applications

    CERN Document Server

    Elliott, David L

    1995-01-01

    Ultraviolet Laser Technology and Applications is a hands-on reference text that identifies the main areas of UV laser technology; describes how each is applied; offers clearly illustrated examples of UV opticalsystems applications; and includes technical data on optics, lasers, materials, and systems. This book is unique for its comprehensive, in-depth coverage. Each chapter deals with a different aspect of the subject, beginning with UV light itself; moving through the optics, sources, and systems; and concluding with detailed descriptions of applications in various fields.The text enables pr

  5. Industrial applications of laser; Applications industrielles du laser

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    This technical dossier is a result of a collaboration between the CFE and the Power Laser club with the sustain of the French Ministry of Industry. It presents a catalogue of the industrial applications of the laser technology in France with about 80 technical files about companies using this technology in various domains such as: weapons industry, civil engineering, confection, automotive equipments, electrical equipments, medical applications, instrumentation, tools, sheet iron and steel plate industry etc.. (J.S.)

  6. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    Science.gov (United States)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  7. Laser Beam Scintillation with Applications

    CERN Document Server

    Andrews, Larry C; Young, Cynthia

    2001-01-01

    Renewed interest in laser communication systems has sparked development of useful new analytic models. This book discusses optical scintillation and its impact on system performance in free-space optical communication and laser radar applications, with a detailed look at propagation phenomena and the role of scintillation on system behavior. Intended for practicing engineers, scientists, and students.

  8. Application of lasers in endodontics

    Science.gov (United States)

    Ertl, Thomas P.; Benthin, Hartmut; Majaron, Boris; Mueller, Gerhard J.

    1997-12-01

    Root canal treatment is still a problem in dentistry. Very often the conventional treatment fails and several treatment sessions are necessary to save the tooth from root resection or extraction. Application of lasers may help in this situation. Bacteria reduction has been demonstrated both in vitro and clinically and is either based on laser induced thermal effects or by using an ultraviolet light source. Root canal cleansing is possible by Er:YAG/YSGG-Lasers, using the hydrodynamic motion of a fluid filled in the canals. However root canal shaping using lasers is still a problem. Via falsas and fiber breakage are points of research.

  9. Quantum cascade laser as a mid-infrared photovoltaic and photoconductive detector

    Science.gov (United States)

    Chen, Xing; Shyu, David; Choa, Fow-Sen; Trivedi, Sudhir

    2011-06-01

    We report the operation of quantum cascade lasers (QCLs) as a mid-infrared (mid-IR) photo-detector under both photovoltaic and photoconductive modes. When operated at photoconductive mode, negative photo-conductance is observed at low bias current. The photo-conductance of the device changes from negative to positive when the bias is increased over a transparency point. These interesting mid-IR detection characteristics of QCL gain material can help and simplify the design and testing of mid-IR photonic integrated devices and circuits by using them to measure the coupling and waveguide loss and provide gain at any location in a mid-IR photonic circuit.

  10. Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

    Science.gov (United States)

    Terabayashi, Ryohei; Sonnenschein, Volker; Tomita, Hideki; Hayashi, Noriyoshi; Kato, Shusuke; Jin, Lei; Yamanaka, Masahito; Nishizawa, Norihiko; Sato, Atsushi; Nozawa, Kohei; Hashizume, Kenta; Oh-hara, Toshinari; Iguchi, Tetsuo

    2017-11-01

    A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

  11. Switching circuit to improve the frequency modulation difference-intensity THz quantum cascade laser imaging

    Energy Technology Data Exchange (ETDEWEB)

    Saat, N. K. [Department of Physics, Faculty of Science, University Putra Malaysia (Malaysia); Dean, P.; Khanna, S. P.; Salih, M.; Linfield, E. H.; Davies, A. G. [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)

    2015-04-24

    We demonstrate new switching circuit for difference-intensity THz quantum cascade laser (QCL) imaging by amplitude modulation and lock in detection. The switching circuit is designed to improve the frequency modulation so that it can stably lock the amplitude modulation of the QCL and the detector output. The combination of a voltage divider and a buffer in switching circuit to quickly switch the amplitude of the QCL biases of 15.8 V and 17.2 V is successfully to increase the frequency modulation up to ∼100 Hz.

  12. Widely tunable terahertz source based on intra-cavity frequency mixing in quantum cascade laser arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Aiting; Jung, Seungyong; Jiang, Yifan; Kim, Jae Hyun; Belkin, Mikhail A., E-mail: mbelkin@ece.utexas.edu [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Vijayraghavan, Karun [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); ATX Photonics, 10100 Burnet Rd., Austin, Texas 78758 (United States)

    2015-06-29

    We demonstrate a compact monolithic terahertz source continuously tunable from 1.9 THz to 3.9 THz with the maximum peak power output of 106 μW at 3.46 THz at room temperature. The source consists of an array of 10 electrically tunable quantum cascade lasers with intra-cavity terahertz difference-frequency generation. To increase fabrication yield and achieve high THz peak power output in our devices, a dual-section current pumping scheme is implemented using two electrically isolated grating sections to independently control gain for the two mid-IR pumps.

  13. Laser anemometer measurements in an annular cascade of core turbine vanes and comparison with theory

    Science.gov (United States)

    Goldman, L. J.; Seashultz, R. G.

    1982-01-01

    Laser measurements were made in an annular cascade of stator vanes operating at an exit critical velocity ratio of 0.78. Velocity and flow angles in the blade to blade plane were obtained at every 10 percent of axial chord within the passage and at 1/2 axial chord downstream of the vanes for radial positions near the hub, mean and tip. Results are presented in both plot and tabulated form and are compared with calculations from an inviscid, quasi three dimensional computer program. The experimental measurements generally agreed well with these theoretical calculations, an indication of the usefulness of this analytic approach.

  14. External-cavity beam combining of 4-channel quantum cascade lasers

    Science.gov (United States)

    Zhao, Yue; Zhang, Jin-Chuan; Zhou, Yu-Hong; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    We demonstrate an external-cavity (EC) beam combining of 4-channel quantum cascade lasers (QCLs) with an output coupler which makes different QCL beams propagating coaxially. A beam combining efficiency of 35% (up to 75% near threshold) is obtained with a beam quality M2 of 5.5. A peak power of 0.64 W is achieved at a wavelength of 4.7 μm. The differences of spot characteristic between coupled and uncoupled are also showed in this letter. The QCLs in this EC system do not have heat crosstalk so that the system can be used for high power beam combining of QCLs.

  15. Integration of a terahertz quantum cascade laser with a hollow waveguide

    Science.gov (United States)

    Wanke, Michael C [Albuquerque, NM; Nordquist, Christopher D [Albuquerque, NM

    2012-07-03

    The present invention is directed to the integration of a quantum cascade laser with a hollow waveguide on a chip to improve both the beam pattern and manufacturability. By coupling the QCL output into a single-mode rectangular waveguide the radiation mode structure can be known and the propagation, manipulation, and broadcast of the QCL radiation can then be entirely controlled by well-established rectangular waveguide techniques. By controlling the impedance of the interface, enhanced functions, such as creating amplifiers, efficient coupling to external cavities, and increasing power output from metal-metal THz QCLs, are also enabled.

  16. Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing Lasers

    Directory of Open Access Journals (Sweden)

    Belkacem Meziane

    2008-01-01

    Full Text Available A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development.

  17. Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Terabayashi, Ryohei, E-mail: terabayashi.ryouhei@h.mbox.nagoya-u.ac.jp; Sonnenschein, Volker, E-mail: volker@nagoya-u.jp; Tomita, Hideki, E-mail: tomita@nagoya-u.jp; Hayashi, Noriyoshi, E-mail: hayashi.noriyoshi@h.mbox.nagoya-u.ac.jp; Kato, Shusuke, E-mail: katou.shuusuke@f.mbox.nagoya-u.ac.jp; Jin, Lei, E-mail: kin@nuee.nagoya-u.ac.jp; Yamanaka, Masahito, E-mail: yamanaka@nuee.nagoya-u.ac.jp; Nishizawa, Norihiko, E-mail: nishizawa@nuee.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan); Sato, Atsushi, E-mail: atsushi.sato@sekisui.com; Nozawa, Kohei, E-mail: kohei.nozawa@sekisui.com; Hashizume, Kenta, E-mail: kenta.hashizume@sekisui.com; Oh-hara, Toshinari, E-mail: toshinari.ohara@sekisui.com [Sekisui Medical Co., Ltd., Drug Development Solutions Center (Japan); Iguchi, Tetsuo, E-mail: t-iguchi@nucl.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan)

    2017-11-15

    A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

  18. Faraday rotation spectroscopy of nitrogen dioxide based on a widely tunable external cavity quantum cascade laser

    Science.gov (United States)

    Zaugg, Christian A.; Lewicki, Rafal; Day, Tim; Curl, Robert F.; Tittel, Frank K.

    2011-01-01

    Faraday Rotation Spectroscopy (FRS) is a technique for the sensitive and selective detection of paramagnetic molecules or radicals such as NO, NO2, O2 or OH-. Moreover FRS is suitable for atmospheric measurements due to the insensitivity to non-paramagnetic interfering molecules such as H2O and CO2. Experimental results of an FRS sensor for the NO2detection employing an external-cavity quantum cascade laser (EC-QCL) are reported. The CW EC-QCL exhibits modehop free (MHF) tuning between 1600 cm-1 and 1650 cm-1. This allows targeting the optimum 441constant (TC).

  19. Compact quantum cascade laser based quartz-enhanced photoacoustic spectroscopy sensor system for detection of carbon disulfide.

    Science.gov (United States)

    Waclawek, Johannes P; Moser, Harald; Lendl, Bernhard

    2016-03-21

    A compact gas sensor system based on quartz-enhanced photoacoustic spectroscopy (QEPAS) employing a continuous wave (CW) distributed feedback quantum cascade laser (DFB-QCL) operating at 4.59 µm was developed for detection of carbon disulfide (CS2) in air at trace concentration. The influence of water vapor on monitored QEPAS signal was investigated to enable compensation of this dependence by independent moisture sensing. A 1 σ limit of detection of 28 parts per billion by volume (ppbv) for a 1 s lock-in amplifier time constant was obtained for the CS2 line centered at 2178.69 cm-1 when the gas sample was moisturized with 2.3 vol% H2O. The work reports the suitability of the system for monitoring CS2 with high selectivity and sensitivity, as well as low sample gas volume requirements and fast sensor response for applications such as workplace air and process monitoring at industry.

  20. Ultrabright GeV Photon Source via Controlled Electromagnetic Cascades in Laser-Dipole Waves

    Science.gov (United States)

    Gonoskov, A.; Bashinov, A.; Bastrakov, S.; Efimenko, E.; Ilderton, A.; Kim, A.; Marklund, M.; Meyerov, I.; Muraviev, A.; Sergeev, A.

    2017-10-01

    Electromagnetic cascades have the potential to act as a high-energy photon source of unprecedented brightness. Such a source would offer new experimental possibilities in fundamental science, but in the cascade process radiation reaction and rapid electron-positron plasma production seemingly restrict the efficient production of photons to sub-GeV energies. Here, we show how to overcome these energetic restrictions and how to create a directed GeV photon source, with unique capabilities as compared to existing sources. Our new source concept is based on a controlled interplay between the cascade and anomalous radiative trapping. Using specially designed advanced numerical models supported with analytical estimates, we demonstrate that the concept becomes feasible at laser powers of around 7 PW, which is accessible at soon-to-be-available facilities. A higher peak power of 40 PW can provide 1 09 photons with GeV energies in a well-collimated 3-fs beam, achieving peak brilliance 9 ×1024 ph s-1 mrad-2 mm-2/0.1 %BW .

  1. Dental Lasers and Application Fields in Endodontics

    OpenAIRE

    Emrah Çetin; Hicran Dönmez Özkan; Senem Gökçen Yiğit Özer

    2017-01-01

    Since the first laser application in endodontics by Weichman in 1971, search for new laser devices is being proposed with the rapid development of laser technology. The purpose of this article is to update the information on laser application fields in endodontics and give information regarding the advantages and limitations of the laser devices.

  2. Dental Lasers and Application Fields in Endodontics

    Directory of Open Access Journals (Sweden)

    Emrah Çetin

    2017-04-01

    Full Text Available Since the first laser application in endodontics by Weichman in 1971, search for new laser devices is being proposed with the rapid development of laser technology. The purpose of this article is to update the information on laser application fields in endodontics and give information regarding the advantages and limitations of the laser devices.

  3. Optimizing the active region of interband cascade lasers for passive mode-locking

    Directory of Open Access Journals (Sweden)

    K. Ryczko

    2017-01-01

    Full Text Available The work proposes possible designs of active regions for a mode-locked interband cascade laser emitting in the mid infrared. For that purpose we investigated the electronic structure properties of respectively modified GaSb-based type II W-shaped quantum wells, including the effect of external bias in order to simultaneously fulfil the requirements for both the absorber as well as the gain sections of a device. The results show that introducing multiple InAs layers in type II InAs/GaInSb quantum wells or introducing a tensely-strained GaAsSb layer into “W-shaped” type II QWs offers significant difference in optical transitions’ oscillator strengths (characteristic lifetimes of the two oppositely polarized parts of such a laser, being promising for utilization in mode-locked devices.

  4. Detection of multiple chemicals based on external cavity quantum cascade laser spectroscopy

    Science.gov (United States)

    Sun, Juan; Ding, Junya; Liu, Ningwu; Yang, Guangxiang; Li, Jingsong

    2018-02-01

    A laser spectroscopy system based on a broadband tunable external cavity quantum cascade laser (ECQCL) and a mini quartz crystal tuning fork (QCTF) detector was developed for standoff detection of volatile organic compounds (VOCs). The self-established spectral analysis model based on multiple algorithms for quantitative and qualitative analysis of VOC components (i.e. ethanol and acetone) was detailedly investigated in both closed cell and open path configurations. A good agreement was obtained between the experimentally observed spectra and the standard reference spectra. For open path detection of VOCs, the sensor system was demonstrated at a distance of 30 m. The preliminary laboratory results show that standoff detection of VOCs at a distance of over 100 m is very promising.

  5. Comb-assisted subkilohertz linewidth quantum cascade laser for high-precision mid-infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Galli, I.; Cappelli, F.; Bartalini, S.; Mazzotti, D.; Giusfredi, G.; Cancio, P.; De Natale, P. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Siciliani de Cumis, M. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); Borri, S. [CNR-IFN-Istituto di Fotonica e Nanotecnologie, Via Amendola 173, 70126 Bari, BA (Italy); Montori, A. [LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

    2013-03-25

    We report on the linewidth narrowing of a room-temperature mid-infrared quantum cascade laser by phase-locking to a difference-frequency-generated radiation referenced to an optical frequency comb synthesizer. A locking bandwidth of 250 kHz, with a residual rms phase-noise of 0.56 rad, has been achieved. The laser linewidth is narrowed by more than 2 orders of magnitude below 1 kHz, and its frequency is stabilized with an absolute traceability of 2 Multiplication-Sign 10{sup -12}. This source has allowed the measurement of the absolute frequency of a CO{sub 2} molecular transition with an uncertainty of about 1 kHz.

  6. Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

    Energy Technology Data Exchange (ETDEWEB)

    Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland); Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch; Tardy, Camille; Terazzi, Romain; Gresch, Tobias; Blaser, Stéphane; Muller, Antoine [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Faist, Jerome [Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland)

    2015-11-30

    In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolution molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.

  7. Civilian applications of laser fusion

    Energy Technology Data Exchange (ETDEWEB)

    Maniscalco, J.; Blink, J.; Buntzen, R.; Hovingh, J.; Meier, W.; Monsler, M.; Walker, P.

    1978-08-14

    The commercial aspects of laser fusion were evaluated in an attempt to relate the end products (neutrons and energy) to significant commercial applications. We have found that by far the largest markets and highest payoffs for laser fusion are associated with electric power production. Hence, much of this report evaluates the prospects of producing commercial electricity with laser fusion. To this end, we have described in detail a new and promising laser fusion concept--the liquid lithium waterfall reactor. In addition, we have taken the most attractive features from our laser fusion studies and used them to compare laser fusion to other long-range sources of energy (breeder reactors and solar energy). It is our contention that all three sources of electrical energy should be developed to the point where the final selections are primarily based on economic competitiveness. The other potential applications of laser fusion (fissile fuel production, synthetic fuel production, actinide burning, and propulsion) are also discussed, and our preliminary plan for the engineering development of laser fusion is presented.

  8. Civilian applications of laser fusion

    Energy Technology Data Exchange (ETDEWEB)

    Maniscalco, J.; Blink, J.; Buntzen, R.; Hovingh, J.; Meier, W.; Monsler, M.; Walker, P.

    1977-11-17

    The commercial aspects of laser fusion were evaluated in an attempt to relate the end products (neutrons and energy) to significant commercial applications. It was found that by far the largest markets and highest payoffs for laser fusion are associated with electric power production. Hence, much of this report evaluates the prospects of producing commercial electricity with laser fusion. To this end, we have described in detail a new and promising laser fusion concept--the liquid lithium waterfall reactor. In addition, we have taken the most attractive features from our laser studies and used them to compare laser fusion to other long-range sources of energy (breeder reactors and solar energy). It is our contention that all three sources of electrical energy should be developed to the point where the final selections are primarily based on economic competitiveness. The other potential applications of laser fusion (fissile fuel production, synthetic fuel production, actinide burning, and propulsion) are also discussed, and our preliminary plan for the engineering development of laser fusion is presented.

  9. Optimizing optical nonlinearities in GaInAs/AlInAs quantum cascade lasers

    Directory of Open Access Journals (Sweden)

    Gajić Aleksandra D.

    2014-01-01

    Full Text Available Regardless of the huge advances made in the design and fabrication of mid-infrared and terahertz quantum cascade lasers, success in accessing the ~3-4 mm region of the electromagnetic spectrum has remained limited. This fact has brought about the need to exploit resonant intersubband transitions as powerful nonlinear oscillators, consequently enabling the occurrence of large nonlinear optical susceptibilities as a means of reaching desired wavelengths. In this work, we present a computational model developed for the optimization of second-order optical nonlinearities in In0.53Ga0.47As/Al0.48In0.52As quantum cascade laser structures based on the implementation of the Genetic algorithm. The carrier transport and the power output of the structure were calculated by self-consistent solutions to the system of rate equations for carriers and photons. Both stimulated and simultaneous double-photon absorption processes occurring between the second harmonic generation-relevant levels are incorporated into rate equations and the material-dependent effective mass and band non-parabolicity are taken into account, as well. The developed method is quite general and can be applied to any higher order effect which requires the inclusion of the photon density equation. [Projekat Ministarstva nauke Republike Srbije, br. III 45010

  10. Lasers and optoelectronics fundamentals, devices and applications

    CERN Document Server

    Maini, Anil K

    2013-01-01

    With emphasis on the physical and engineering principles, this book provides a comprehensive and highly accessible treatment of modern lasers and optoelectronics. Divided into four parts, it explains laser fundamentals, types of lasers, laser electronics & optoelectronics, and laser applications, covering each of the topics in their entirety, from basic fundamentals to advanced concepts. Key features include: exploration of technological and application-related aspects of lasers and optoelectronics, detailing both existing and emerging applications in industry, medical diag

  11. 5.5 W of Diffraction-Limited Green Light Generated by SFG of Tapered Diode Lasers in a Cascade of Nonlinear Crystals

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Jensen, Ole Bjarlin; Andersen, Peter Eskil

    2015-01-01

    Diode-based high power visible lasers are perfect pump sources for, e.g., titaniumsapphire lasers. The combination of favorable scaling laws in both SFG and cascading of nonlinear crystals allows access to unprecedented powers in diode-based systems.......Diode-based high power visible lasers are perfect pump sources for, e.g., titaniumsapphire lasers. The combination of favorable scaling laws in both SFG and cascading of nonlinear crystals allows access to unprecedented powers in diode-based systems....

  12. Laser Science and Applications

    Science.gov (United States)

    El-Nadi, Lotfia M.; Mansour, Mohy S.

    2010-04-01

    Attosecond high harmonic pulses: generation and characterization / C. H. Nam and K. T. Kim -- High power lasers and interactions / C. Chatwin and R. Young -- Laser accelerators / L. M. El-Nadi ... [et al.] -- Energy levels, oscillator strengths, lifetimes, and gain distributions of S VII, CI VIII, and Ar IX / Wessameldin. S. Abdelaziz and Th. M. El-Sherbini -- The gain distribution according to theoretical level structure and decay dynamics of W[symbol] / H. M. Hamed ... [et al.] -- Raman spectroscopy and low temperature photoluminescence ZnSe[symbol]Te[symbol] ternary alloys / A. Salah ... [et al.] -- Automated polarization-discrimination technique to minimize lidar detected skylight background noise, part I / Y. Y. Hassebo, K. Elsayed and S. Ahmed -- Laser interferometric measurements of the physical properties for He, Ne gases and their mixture / N. M. Abdel-Moniem ... [et al.] -- Analytical studies of laser beam propagation through the atmosphere / M. I. El-Saftawy, A. M. Abd El-Hamed and N. Sh. Kalifa -- Laser techniques in conservation of artworks: problems and breakthroughs / R. Salimbeni and S. Siano -- Technology-aided heritage conservation laser cleaning for buildings / M. S. Nada -- Technology significance in conservation of the built heritage 3D visualization impact / M. S. Nada -- Simulation of optical resonators for Vertical-Cavity Surface-Emitting Lasers (VCSEL) / M. S. Mansour ... [et al.] -- Optical design alternatives: a survey study / A. A. K. Ismail, I. A. S. Ismail and S. H. Ahmed -- Materials for digital optical design; a survey study / A. A. K. Ismail, I. A. S. Ismail and S. H. Ahmed -- Proposed design for optical digital circuits / A. A. K. Ismail, I. A. S. Ismail and S. H. Ahmed -- Photo-induced effect on bacterial cells / M. H. El Batanouny ... [et al.] -- Laser and non-coherent light effect on peripheral blood normal and acute lymphoblastic leukemic cells by using different types of photosensitizers / M. H. El Batanouny ... [et al

  13. Temperature performance analysis of intersubband Raman laser in quantum cascade structures

    Science.gov (United States)

    Yousefvand, Hossein Reza

    2017-06-01

    In this paper we investigate the effects of temperature on the output characteristics of the intersubband Raman laser (RL) that integrated monolithically with a quantum cascade (QC) laser as an intracavity optical pump. The laser bandstructure is calculated by a self-consistent solution of Schrodinger-Poisson equations, and the employed physical model of carrier transport is based on a five-level carrier scattering rates; a two-level rate equations for the pump laser and a three-level scattering rates to include the stimulated Raman process in the RL. The temperature dependency of the relevant physical effects such as thermal broadening of the intersubband transitions (ISTs), thermally activated phonon emission lifetimes, and thermal backfilling of the final lasing state of the Raman process from the injector are included in the model. Using the presented model, the steady-state, small-signal modulation response and transient device characteristics are investigated for a range of sink temperatures (80-220 K). It is found that the main characteristics of the device such as output power, threshold current, Raman modal gain, turn-on delay time and 3-dB optical bandwidth are remarkably affected by the temperature.

  14. Laser-tissue interaction of a continuous-wave 2-μm, 3-μm cascade oscillation fiber laser: sharp incision with controlled coagulation layer thickness

    Science.gov (United States)

    Arai, Tsunenori; Sumiyoshi, Tetsumi; Naruse, Kyota; Ishihara, Miya; Sato, Shunichi; Kikuchi, Makoto; Kasamatsu, Tadashi; Sekita, Hitoshi; Obara, Minoru

    2000-06-01

    We studied coagulation layer controlled incision with newly developed continuous wave 2 micrometer, 3 micrometer cascade oscillation fiber laser in vitro. Since this laser device simultaneously oscillates 2 micrometer and 3 micrometer radiation, we could change tissue interaction by arranging power ratio of 2 micrometer to 3 micrometer radiation. About one watt of total irradiation power with various power ratios was focused to extracted fresh porcine myocardium or anesthetized rabbit on an automatic moving stage to obtain line incision. Macro photograph and microscopic histology were used to observe tissue interaction phenomenon. The incised specimen showed that precise cutting groove with thin coagulation layer was attained by a 3 micrometer based radiation, meanwhile addition of 2 micrometer radiation to 3 micrometer radiation made coagulation layer thicker. A heat conduction simulator using finite-element method was used to qualitatively explain obtained coagulation layer thickness. This precise incision with controllable side coagulation layer may effective to control bleeding during incision, for instance, for skin, liver, and kidney incisions. Pure continuous wave radiation of 2 micrometer and 3 micrometer may eliminate stress wave induced tissue damage which is frequently found in Ho:YAG and/or Er:YAG tissue interactions. Moreover, sapphire fiber might offer flexible power delivery to this new laser to establish endoscopic application and/or to improved beam handling.

  15. Quantum Cascade Lasers (QCLs) for standoff explosives detection : LDRD 138733 final report.

    Energy Technology Data Exchange (ETDEWEB)

    Theisen, Lisa Anne; Linker, Kevin Lane

    2009-09-01

    Continued acts of terrorism using explosive materials throughout the world have led to great interest in explosives detection technology, especially technologies that have a potential for remote or standoff detection. This LDRD was undertaken to investigate the benefit of the possible use of quantum cascade lasers (QCLs) in standoff explosives detection equipment. Standoff detection of explosives is currently one of the most difficult problems facing the explosives detection community. Increased domestic and troop security could be achieved through the remote detection of explosives. An effective remote or standoff explosives detection capability would save lives and prevent losses of mission-critical resources by increasing the distance between the explosives and the intended targets and/or security forces. Many sectors of the US government are urgently attempting to obtain useful equipment to deploy to our troops currently serving in hostile environments. This LDRD was undertaken to investigate the potential benefits of utilizing quantum cascade lasers (QCLs) in standoff detection systems. This report documents the potential opportunities that Sandia National Laboratories can contribute to the field of QCL development. The following is a list of areas where SNL can contribute: (1) Determine optimal wavelengths for standoff explosives detection utilizing QCLs; (2) Optimize the photon collection and detection efficiency of a detection system for optical spectroscopy; (3) Develop QCLs with broader wavelength tunability (current technology is a 10% change in wavelength) while maintaining high efficiency; (4) Perform system engineering in the design of a complete detection system and not just the laser head; and (5) Perform real-world testing with explosive materials with commercial prototype detection systems.

  16. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing

    Directory of Open Access Journals (Sweden)

    Simone Borri

    2016-02-01

    Full Text Available The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

  17. Tunable Microcavity-Stabilized Quantum Cascade Laser for Mid-IR High-Resolution Spectroscopy and Sensing.

    Science.gov (United States)

    Borri, Simone; Siciliani de Cumis, Mario; Insero, Giacomo; Bartalini, Saverio; Cancio Pastor, Pablo; Mazzotti, Davide; Galli, Iacopo; Giusfredi, Giovanni; Santambrogio, Gabriele; Savchenkov, Anatoliy; Eliyahu, Danny; Ilchenko, Vladimir; Akikusa, Naota; Matsko, Andrey; Maleki, Lute; De Natale, Paolo

    2016-02-17

    The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF₂ microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line.

  18. Argon laser application to endodontics

    Science.gov (United States)

    Blankenau, Richard J.; Ludlow, Marvin; Anderson, David

    1993-07-01

    The application of laser technology to endodontics has been studied for some time. At the present time several major problems are being investigated: (1) removal of infected tissues, (2) sterilization of canals, (3) obturation of canals, and (4) preservation of the vitality of supporting tissues. This list is not intended to imply other problems do not exist or have been solved, but it is a starting point. This paper reviews some of the literature that relates to laser applications to endodontics and concludes with some of the findings from our investigation.

  19. Three-dimensional laser anemometer measurements in a linear turbine vane cascade

    Science.gov (United States)

    Zimmerman, D. R.

    Laser anemometer (LDA) measurements are presented which were made in a transparent test-section containing a linear cascade of four C3X turbine vanes. The velocity components corresponding to the 'axial' and 'circumferential' components were measured with the 0.4880 (blue) and 0.4765 micrometer (violet) wavelengths from an argon-ion laser. The blue and violet beams were transmitted through the transparent sidewalls. The 'radial' velocity component was measured with the 0.5145 micrometer (green) wavelength from the same laser. The green beams, aimed downstream through the inlet, were brought into position with a fiber optic cable and an optical train identical to the blue and violet optics. The three-color, six-beam, mutually-orthogonal LDA was brought to a common focal point. The optics were fixed in space and the test section was mounted on a milling machine. The data acquisition by three photomultipliers and three frequency counters was controlled by a coincidence timer and a microcomputer.

  20. Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

    Science.gov (United States)

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2013-06-01

    The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

  1. Laser Applications: Implications for Vocational Education.

    Science.gov (United States)

    Fraser, Jeannette L.

    Recent and projected advances in and commercial applications of lasers and laser technology were examined in order to assist vocational planners in responding to skill needs that will be created by lasers in the next few years. Until recently, most laser applications were in research and development settings; however, in the last several years…

  2. Hot electron bolometer heterodyne receiver with a 4.7-THz quantum cascade laser as a local oscillator

    NARCIS (Netherlands)

    Kloosterman, J.L.; Hayton, D.J.; Ren, Y.; Kao, T.Y.; Hovenier, J.N.; Gao, J.R.; Klapwijk, T.M.; Hu, Q.; Walker, C.K.; Reno, J.L.

    2013-01-01

    We report on a heterodyne receiver designed to observe the astrophysically important neutral atomic oxygen [OI] line at 4.7448?THz. The local oscillator is a third-order distributed feedback quantum cascade laser operating in continuous wave mode at 4.741?THz. A quasi-optical, superconducting NbN

  3. Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera

    OpenAIRE

    Behnken, Barry N.; Karunasiri, Gamani; Chamberlin, Danielle R.; Peter R. Robrish; Faist, Jerome

    2008-01-01

    Optics Letters, Volume 33, No. 5, pp. 440-442 (March 1, 2008) Real-time imaging in the terahertz (THz) spectral range was achieved using a milliwatt-scale, 2.8 THz quantum cascade laser and an uncooled, 160 120 pixel microbolometer camera modified with Picarin optics... This work is supported by the Air Force Office of Scientific Research (AFOSR).

  4. Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

    KAUST Repository

    Nasir, Ehson Fawad

    2016-07-16

    A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm were operated in pulsed mode, causing a frequency "down-chirp" across two ro-vibrational transitions of carbon monoxide. The down-chirp phenomenon resulted in large spectral tuning (δν ∼2.8cm-1) within a single pulse of each laser at a high pulse repetition frequency (100kHz). The wide tuning range allowed the application of the two-line thermometry technique, thus making the sensor quantitative and calibration-free. The sensor was first tested in non-reactive CO-N2 gas mixtures in the RCM and then applied to cases of n-pentane oxidation. Experiments were carried out for end of compression (EOC) pressures and temperatures ranging 9.21-15.32bar and 745-827K, respectively. Measured EOC temperatures agreed with isentropic calculations within 5%. Temperature rise measured during the first-stage ignition of n-pentane is over-predicted by zero-dimensional kinetic simulations. This work presents, for the first time, highly time-resolved temperature measurements in reactive and non-reactive rapid compression machine experiments. © 2016 Elsevier Ltd.

  5. Optical-feedback cavity-enhanced absorption spectroscopy with a quantum-cascade laser yields the lowest formaldehyde detection limit

    Science.gov (United States)

    Gorrotxategi-Carbajo, P.; Fasci, E.; Ventrillard, I.; Carras, M.; Maisons, G.; Romanini, D.

    2013-03-01

    We report on the first application of Optical Feedback-Cavity Enhanced Absorption Spectroscopy to formaldehyde trace gas analysis at mid-infrared wavelengths. A continuous-wave room-temperature, distributed-feedback quantum cascade laser emitting around 1,769 cm-1 has been successfully coupled to an optical cavity with finesse 10,000 in an OF-CEAS spectrometer operating on the ν2 fundamental absorption band of formaldehyde. This compact setup (easily transportable) is able to monitor H2CO at ambient concentrations within few seconds, presently limited by the sample exchange rate. The minimum detectable absorption is 1.6 × 10-9 cm-1 for a single laser scan (100 ms, 100 data points), with a detectable H2CO mixing ratio of 60 pptv at 10 Hz. The corresponding detection limit at 1 Hz is 5 × 10-10 cm-1, with a normalized figure of merit of 5 × 10-11cm^{-1}/sqrtHz (100 data points recorded in each spectrum taken at 10 Hz rate). A preliminary Allan variance analysis shows white noise averaging down to a minimum detection limit of 5 pptv at an optimal integration time of 10 s, which is significantly better than previous results based on multi-pass or cavity-enhanced tunable QCL absorption spectroscopy.

  6. Quantum cascade laser photoacoustic detection of nitrous oxide released from soils for biofuel production

    Science.gov (United States)

    Couto, F. M.; Sthel, M. S.; Castro, M. P. P.; da Silva, M. G.; Rocha, M. V.; Tavares, J. R.; Veiga, C. F. M.; Vargas, H.

    2014-12-01

    In order to investigate the generation of greenhouse gases in sugarcane ethanol production chain, a comparative study of N2O emission in artificially fertilized soils and soils free from fertilizers was carried out. Photoacoustic spectroscopy using quantum cascade laser with an emission ranging from 7.71 to 7.88 µm and differential photoacoustic cell were applied to detect nitrous oxide (N2O), an important greenhouse gas emitted from soils cultivated with sugar cane. Owing to calibrate the experimental setup, an initial N2O concentration was diluted with pure nitrogen and detection limit of 50 ppbv was achieved. The proposed methodology was selective and sensitive enough to detect N2O from no fertilized and artificially fertilized soils. The measured N2O concentration ranged from ppmv to ppbv.

  7. High power, low divergent, substrate emitting quantum cascade ring laser in continuous wave operation

    Directory of Open Access Journals (Sweden)

    D. H. Wu

    2017-03-01

    Full Text Available We demonstrate a surface grating coupled substrate emitting quantum cascade ring laser with high power room temperature continuous wave operation at 4.64 μm. A second order surface metal/semiconductor distributed-feedback grating is used for in-plane feedback and vertical out-coupling. A device with 400 μm radius ring cavity exhibits an output power of 202 mW in room temperature continuous wave operation. Single mode operation with a side mode suppression ratio of 25 dB is obtained along with a good linear tuning with temperature. The far field measurement exhibits a low divergent concentric ring beam pattern with a lobe separation of ∼0.34°, which indicates that the device operates in fundamental mode (n = 1.

  8. Regrowth of quantum cascade laser active regions on metamorphic buffer layers

    Science.gov (United States)

    Rajeev, A.; Mawst, L. J.; Kirch, J. D.; Botez, D.; Miao, J.; Buelow, P.; Kuech, T. F.; Li, Xiaoqing; Sigler, C.; Babcock, S. E.; Earles, T.

    2016-10-01

    Metamorphic buffer layers (MBLs) were used as substrates with lattice constants selected for designing and fabricating intersubband transition sources involving strained superlattices (SLs) such as Quantum Cascade Lasers (QCLs). Chemical mechanical planarization (CMP) was used to prepare the InGaAs-based MBLs for epitaxial growth. Indium enrichment of the InGaAs layer on the MBL surfaces was observed when annealed at the regrowth temperatures. This post-anneal enhancement was eliminated by including a wet-etch treatment after CMP, which results in an epi-ready surface for regrowth. Ten stages of a QCL core region structure, designed for emission at a 3.4 μm wavelength are regrown on a surface-optimized MBL. Such structures exhibit well defined X-ray diffraction pendellösung fringes, and transmission electron microscopy confirms planar superlattice interfaces with layer thicknesses that are in good agreement with the design target.

  9. QEPAS nitric oxide sensor based on a mid-infrared fiber-coupled quantum cascade laser

    Science.gov (United States)

    Ren, Wei; Shi, Chao; Wang, Zhen; Yao, Chenyu

    2017-04-01

    We report a quartz-enhanced photoacoustic sensor (QEPAS) for nitric oxide (NO) detection using a mid-infrared fibercoupled quantum cascade laser (QCL) near 5.2 μm. The QCL radiation was coupled into an InF3 fiber (100 μm core diameter) for light delivery to the quartz tuning fork, a tiny piezoelectric element converting the acoustic wave induced mechanical vibration to the gas-absorption associated electrical signal. This mid-infrared fiber can achieve nearly single-mode light delivery for the target wavelength. The off-beam configuration was adopted for the fiber-coupled detection considering its simpler installation, optical alignment and comparative sensitivity to the traditional on-beam setup.

  10. THz quartz-enhanced photoacoustic sensor employing a quantum cascade laser source

    Science.gov (United States)

    Spagnolo, V.; Patimisco, P.; Borri, S.; Sampaolo, A.; Scamarcio, G.; Vitiello, M. S.; Beere, H. E.; Ritchie, D. A.

    2013-12-01

    We report on an innovative quartz enhanced photoacoustic (QEPAS) gas sensor operating in the THz spectral range, employing a custom quartz tuning fork (QTF) with the two prongs spaced by ~800 μm. To test our sensor we employed a quantum cascade laser light source and selected a methanol rotational absorption line falling at 131.054 cm-1 (~3.93 THz), with line-strength S = 4.28•10-21 cm. The sensor operated at 10 Torr pressure on the QTF first flexion resonance frequency at 4245 Hz. We achieved a QEPAS normalized noise-equivalent absorption of 2•10-10 W·cm-1•Hz-1/2 comparable with the best result of mid-IR QEPAS systems.

  11. Applications of lasers and electro-optics

    Science.gov (United States)

    Tan, B. C.; Low, K. S.; Chen, Y. H.; Ahmad, Harith; Tou, T. Y.

    Supported by the IRPA Programme on Laser Technology and Applications, many types of lasers have been designed, constructed and applied in various areas of science, medicine and industries. Amongst these lasers constructed were high power carbon dioxide lasers, rare gas halide excimer lasers, solid state Neodymium-YAG lasers, nitrogen lasers, flashlamp pumped dye lasers and nitrogen and excimer laser pumped dye lasers. These lasers and the associated electro-optics system, some with computer controlled, are designed and developed for the following areas of applications: (1) industrial applications of high power carbon dioxide lasers for making of i.c. components and other materials processing purposes -- prototype operational systems have been developed; (2) Medical applications of lasers for cancer treatment using the technique of photodynamic therapy -- a new and more effective treatment protocol has been proposed; (3) agricultural applications of lasers in palm oil and palm fruit-fluorescence diagnostic studies -- fruit ripeness signature has been developed and palm oil oxidation level were investigated; (4) development of atmospheric pollution monitoring systems using laser lidar techniques -- laboratory scale systems were developed; and (5) other applications of lasers including laser holographic and interferometric methods for the non destructive testing of materials.

  12. Ultrashort pulse laser technology laser sources and applications

    CERN Document Server

    Schrempel, Frank; Dausinger, Friedrich

    2016-01-01

    Ultrashort laser pulses with durations in the femtosecond range up to a few picoseconds provide a unique method for precise materials processing or medical applications. Paired with the recent developments in ultrashort pulse lasers, this technology is finding its way into various application fields. The book gives a comprehensive overview of the principles and applications of ultrashort pulse lasers, especially applied to medicine and production technology. Recent advances in laser technology are discussed in detail. This covers the development of reliable and cheap low power laser sources as well as high average power ultrashort pulse lasers for large scale manufacturing. The fundamentals of laser-matter-interaction as well as processing strategies and the required system technology are discussed for these laser sources with respect to precise materials processing. Finally, different applications within medicine, measurement technology or materials processing are highlighted.

  13. Point and standoff detection of trace explosives using quantum cascade lasers

    Science.gov (United States)

    Kim, Seonghwan; Lee, Dongkyu; Liu, Xunchen; Van Neste, C. W.; Thundat, Thomas

    2014-06-01

    Chemical sensors based on micro/nanoelectromechanical systems (M/NEMS) offer many advantages. However, obtaining chemical selectivity in M/NEMS sensors using chemoselective interfaces has been a longstanding challenge. Despite their many advantages, M/NEMS devices relying on chemoselective interfaces do not have sufficient selectivity. Therefore, highly sensitive and selective detection and quantification of chemical molecules using real-time, miniature sensor platforms still remains as a crucial challenge. Incorporating photothermal/photoacoustic spectroscopic techniques with M/NEMS using quantum cascade lasers can provide the chemical selectivity without sacrificing the sensitivity of the miniaturized sensing system. Point sensing is defined as sensing that requires collection and delivery of the target molecules to the sensor for detection and analysis. For example, photothermal cantilever deflection spectroscopy, which combines the high thermomechanical sensitivity of a bimetallic microcantilever with high selectivity of the mid infrared (IR) spectroscopy, is capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules (tens of picogram). On the other hand, standoff sensing is defined as sensing where the sensor and the operator are at distance from the target samples. Therefore, the standoff sensing is a non-contact method of obtaining molecular signatures without sample collection and processing. The distance of detection depends on the power of IR source, the sensitivity of a detector, and the efficiency of the collecting optics. By employing broadly tunable, high power quantum cascade lasers and a boxcar averager, molecular recognition of trace explosive compounds (1 μg/cm2 of RDX) on a stainless steel surface has been achieved at a distance of five meters.

  14. Thermal ablation of WHHLMI rabbit atherosclerotic plaque by quantum cascade laser in the 5.7-μm wavelength range

    Science.gov (United States)

    Hashimura, Keisuke; Ishii, Katsunori; Akikusa, Naota; Edamura, Tadataka; Yoshida, Harumasa; Awazu, Kunio

    2013-03-01

    We evaluated the utility of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques mainly consist of cholesteryl esters. The wavelength of 5.75 μm is well absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal tunica intima of an artery and an atherosclerotic lesions using a nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For realizing a clinical application of this technique, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. In addition QCL irradiation effects to an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal aorta were observed. As a result, the QCL could make cutting difference between the rabbit atherosclerotic aorta and the normal aorta. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depth. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.

  15. Clinical applications of dental lasers.

    Science.gov (United States)

    Lomke, Mitchell A

    2009-01-01

    Dental lasers currently have 24 clinical indications for use that are recognized by the FDA. This article explores the scientific basis for these clinical indications in patient diagnosis and treatment. Multiple examples of relevant clinical applications for these wavelengths are explored in detail and illustrated via clinical photographs.

  16. Application of femtosecond laser in ocular surgery.

    Science.gov (United States)

    Hou, Peili; Lu, Yan; Ye, Fen; Lan, Wen; Huang, Zhenping

    2013-06-01

    The femtosecond laser is a type of laser that can produce pulses of light of extremely short duration. The application of femtosecond laser in surgery results in no thermal effect or shock wave, so that this laser is unlikely to cause tissue injuries outside the irradiation area of the laser beam. The femtosecond laser shows promising applications in refractive surgery and corneal transplantation due to its high precision and predictability. In this paper, we review the clinical application of the femtosecond laser in refractive surgery and corneal transplantation.

  17. Open-path Atmospheric N2O, CO, and NH3 Measurements Using Quantum Cascade Laser Spectroscopy

    Science.gov (United States)

    Sun, K.; Khan, A.; Miller, D. J.; Rafferty, K.; Schreiber, J.; Puzio, C.; Portenti, M.; Silver, J.; Zondlo, M. A.

    2010-12-01

    We develop a compact, mid-infrared quantum cascade (QC) laser based sensor to perform high precision measurements of N2O and CO simultaneously. Since CO is a good tracer of anthropogenic emissions, simultaneous measurements of CO and N2O allow us to correlate the sources of N2O emissions. The thermoelectrically (TE) cooled, and continuous wave QC laser enables room-temperature and unattended operation. The laser is scanned over the absorption features of N2O and CO near 4.54 μm by laser current modulation. A novel cylindrical multi-pass optical cell terminated at the (N/2)th spot is used to simplify the optical configuration by separating the laser and TE cooled detector. Our systems are open-path and non-cryogenic, which avoids vacuum pump and liquid nitrogen. This configuration enables a future design of a non-intrusive, compact (shoe box size), and low-power (10W) sensor. Wavelength modulation spectroscopy (WMS) is used to enhance measurement sensitivity. Higher-harmonic detection (4f and 6f) is performed to improve the resolution between the nearly overlapping N2O and CO lines. Relevant atmospheric N2O and CO concentration is measured, with a detection limit of 0.3 ppbv for N2O and 2 ppbv for CO for 1 s averaging in terms of noise. We also develop an open-path high sensitivity atmospheric ammonia (NH3) sensor using a very similar instrument design. A 9.06 μm QC laser is used to probe absorption features of NH3. Open-path detection of NH3 is even more beneficial due to the surface absorption effect of NH3 and its tendency to readily partition into condensed phases. The NH3 sensor was deployed at the CALNEX 2010 field campaign. The entire system was stable throughout the campaign and acquired data with 10 s time resolution under adverse ambient temperatures and dusty conditions. The measurements were in general agreement with other NH3 and trace gases sensors. Both the N2O/CO and NH3 sensors will be deployed in a local eddy-covariance station to examine long

  18. Cascaded multi-dithering technique using PZT modulators for high control bandwidth in coherent laser beam combining

    Science.gov (United States)

    Ahn, Hee Kyung; Kong, Hong Jin

    2017-09-01

    A cascaded multi-dithering (CMD) technique using piezoelectric ceramic transducer (PZT) tubes as phase modulators is proposed as a tool for obtaining high control bandwidth in coherent laser beam combination. To prove its validity, eight coherent fiber beam elements were combined using the CMD technique with PZT tubes. As a result, residual phase error was recorded to be λ/54 at 100 Hz control bandwidth, which is comparable to that of a four laser beam combination in the previous experiment. To our knowledge, this is the first case to date of combining eight laser beam elements using PZT tubes as phase modulators and achieving such good results.

  19. Theory of intrinsic linewidth based on fluctuation-dissipation balance for thermal photons in THz quantum-cascade lasers.

    Science.gov (United States)

    Yamanishi, Masamichi

    2012-12-17

    Intrinsic linewidth formula modified by taking account of fluctuation-dissipation balance for thermal photons in a THz quantum-cascade laser (QCL) is exhibited. The linewidth formula based on the model that counts explicitly the influence of noisy stimulated emissions due to thermal photons existing inside the laser cavity interprets experimental results on intrinsic linewidth, ~91.1 Hz reported recently with a 2.5 THz bound-to-continuum QCL. The line-broadening induced by thermal photons is estimated to be ~22.4 Hz, i.e., 34% broadening. The modified linewidth formula is utilized as a bench mark in engineering of THz thermal photons inside laser cavities.

  20. Heterogeneous terahertz quantum cascade lasers exceeding 1.9 THz spectral bandwidth and featuring dual comb operation

    Science.gov (United States)

    Rösch, Markus; Beck, Mattias; Süess, Martin J.; Bachmann, Dominic; Unterrainer, Karl; Faist, Jérôme; Scalari, Giacomo

    2018-01-01

    We report on a heterogeneous active region design for terahertz quantum cascade laser based frequency combs. Dynamic range, spectral bandwidth and output power have been significantly improved with respect to previous designs. When individually operating the lasers, narrow and stable intermode beatnote indicate frequency comb operation up to a spectral bandwidth of 1.1 THz, while in a dispersion-dominated regime a bandwidth up to 1.94 THz at a center frequency of 3 THz can be reached. A self-detected dual-comb setup has been used to verify the frequency comb nature of the lasers.

  1. Heterogeneous terahertz quantum cascade lasers exceeding 1.9 THz spectral bandwidth and featuring dual comb operation

    Directory of Open Access Journals (Sweden)

    Rösch Markus

    2018-01-01

    Full Text Available We report on a heterogeneous active region design for terahertz quantum cascade laser based frequency combs. Dynamic range, spectral bandwidth and output power have been significantly improved with respect to previous designs. When individually operating the lasers, narrow and stable intermode beatnote indicate frequency comb operation up to a spectral bandwidth of 1.1 THz, while in a dispersion-dominated regime a bandwidth up to 1.94 THz at a center frequency of 3 THz can be reached. A self-detected dual-comb setup has been used to verify the frequency comb nature of the lasers.

  2. Modeling and theoretical study of electronic anti-Stokes Raman scattering in quantum cascade lasers

    Science.gov (United States)

    Yousefvand, Hossein Reza

    2017-04-01

    This paper presents a self-consistent model for studying the electronic anti-Stokes (AS) Raman scattering in quantum cascade lasers (QCLs). The model is developed by employing a five-level rate-equation for the carrier dynamics in whole of the device and a two-level energy balance equations to adopt the electron-temperature in the pump and AS active regions. Using the presented model, the effect of temperature on the steady and transient characteristics of the device is investigated. Because of considering the parametric interaction between the incident and the scattered lights in the stimulated Raman process, the model accurately predicts the existence of Raman gain's saturation in both the steady and transient regimes. Additionally, using a steady-state analysis of the rate equations in the nonlinear region, an expression for the threshold current of the AS Raman laser is derived and the effects of pump power and temperature are examined. It is found that the electronic AS Raman scattering is affected by interplay between the various temperature-dependent parameters such as the pump intensity, the intrinsic gain of the nonlinear optical medium, and the longitudinal optical (LO) phonon scattering times between the states involved in the stimulated Raman process.

  3. Near-infrared induced optical quenching effects on mid-infrared quantum cascade lasers

    Science.gov (United States)

    Guo, Dingkai; Cai, Hong; Talukder, Muhammad Anisuzzaman; Chen, Xing; Johnson, Anthony M.; Khurgin, Jacob B.; Choa, Fow-Sen

    2014-06-01

    In space communications, atmospheric absorption and Rayleigh scattering are the dominant channel impairments. Transmission using mid-infrared (MIR) wavelengths offers the benefits of lower loss and less scintillation effects. In this work, we report the telecom wavelengths (1.55 μm and 1.3 μm) induced optical quenching effects on MIR quantum cascade lasers (QCLs), when QCLs are operated well above their thresholds. The QCL output power can be near 100% quenched using 20 mW of near-infrared (NIR) power, and the quenching effect depends on the input NIR intensity as well as wavelength. Time resolved measurement was conducted to explore the quenching mechanism. The measured recovery time is around 14 ns, which indicates that NIR generated electron-hole pairs may play a key role in the quenching process. The photocarrier created local field and band bending can effectively deteriorate the dipole transition matrix element and quench the QCL. As a result, MIR QCLs can be used as an optical modulator and switch controlled by NIR lasers. They can also be used as "converters" to convert telecom optical signals into MIR optical signals.

  4. Direct determination of carbon dioxide in aqueous solution using mid-infrared quantum cascade lasers.

    Science.gov (United States)

    Schaden, S; Haberkorn, M; Frank, J; Baena, J R; Lendl, B

    2004-06-01

    A method for the direct determination of carbon dioxide in aqueous solutions using a room-temperature mid-infrared (MIR) quantum cascade laser at 2330 cm(-1) is reported. The absorption values of different carbon dioxide concentrations were measured in a 119 microm CaF2 flow-through cell. An optical system made of parabolic mirrors was used to probe the flow cell and to focus the laser beam on the mercury cadmium telluride (MCT) detector. Aqueous carbon dioxide standards were prepared by feeding different mixtures of gaseous N2 and CO2 through wash bottles at controlled temperature. The concentration of the dissolved CO2 was calculated according to Henry's law, taking into account the temperature and the partial pressure of CO2. The carbon dioxide standards were connected via a selection valve to a peristaltic pump for subsequent, automated measurement in the flow-through cell. A calibration curve was obtained in the range of 0.338 to 1.350 g/L CO2 with a standard deviation of the method sxo equal to 19.4 mg/L CO2. The limit of detection was calculated as three times the baseline noise over time and was determined to be 39 mg/L.

  5. Intra-pulse beam steering in a mid-infrared quantum cascade laser.

    Science.gov (United States)

    Pruszyńska-Karbownik, Emilia; Regiński, Kazimierz; Karbownik, Piotr; Mroziewicz, Bohdan

    The intra-pulse measurements of the beam steering in an AlGaAs/GaAs quantum cascade laser are presented in this paper. The experimental results are explained by a two-mode theoretical model. The near field of the laser radiation is calculated according to the effective index method and transposed to the far field numerically according to Huygens principle. The maximal observed value of deflection of the beam has been found to be [Formula: see text]. For supply currents in the range from 1.6 to 2.4 times the threshold the beam steering occurs only on one side of the resonator axis, and stays is the same for all current values. For higher supply current, it occurs alternately on both sides and exhibits a bistability. The time period of the beam direction change has been found to be about 40 ns for the lowest current and was decreasing with the current increase to about 20 ns.

  6. Discrete Vernier tuning in terahertz quantum cascade lasers using coupled cavities.

    Science.gov (United States)

    Kundu, Iman; Dean, Paul; Valavanis, Alexander; Chen, Li; Li, Lianhe; Cunningham, John E; Linfield, Edmund H; Davies, A Giles

    2014-06-30

    Discrete Vernier frequency tuning of terahertz quantum cascade lasers is demonstrated using a device comprising a two-section coupled-cavity. The two sections are separated by a narrow air gap, which is milled after device packaging using a focused ion beam. One section of the device (the lasing section) is electrically biased above threshold using a short current pulse, while the other section (the tuning section) is biased below threshold with a wider current pulse to achieve controlled localized electrical heating. The resulting thermally-induced shift in the longitudinal cavity modes of the tuning section is engineered to produce either a controllable blue shift or red shift of the emission frequency. This discrete Vernier frequency tuning far exceeds the tuning achievable from standard ridge lasers, and does not lead to any corresponding change in emitted power. Discrete tuning was observed over bandwidths of 50 and 85 GHz in a pair of devices, each using different design schemes. Interchanging the lasing and tuning sections of the same devices yielded red shifts of 20 and 30 GHz, respectively.

  7. Ultraintense lasers and their applications

    Energy Technology Data Exchange (ETDEWEB)

    Mourou, G.A. [University of Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States)

    2001-10-01

    Traditional optics concerns physical phenomena in the electron-volt regime. The new frontier will address giga-electron-volt energy scales. In the last decade, lasers have undergone orders-of-magnitude jumps in peak power, with the invention of the technique of chirped pulse amplification (CPA) and the refinement of femtosecond techniques. Modern CPA lasers can produce intensities greater than 10{sup 21} W/cm{sup 2}, one million times greater than previously possible. These ultraintense lasers give researchers a tool to produce unprecedented pressures (terabars), magnetic fields (gigagauss), temperatures (10{sup 10} K), and accelerations (10{sup 25} g) with applications in fusion energy, nuclear physics, high-energy physics, astrophysics, and cosmology. (author)

  8. CASCADED VOLTAGE STEP-UP CANONICAL ELEMENTS FOR POWER PROCESSING IN PV APPLICATIONS

    OpenAIRE

    Mohamed Abdelkarim, Reham Haroun

    2014-01-01

    In this thesis, cascaded boost converters based on canonical elements under Sliding Mode Control (SMC) will be used as a solution for the high gain conversion ratio in PV applications. The three basic canonical elements for power processing are the DC-transformer, the DC-gyrator and the Loss Free resistor (LFR). Two cascaded boost converters will be synthesized based on one or two canonical elements using single or double sliding surfaces respectively. Different connections will be compared i...

  9. Impedance coordinative control for cascaded converter in bidirectional application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Deng, Fujin

    2016-01-01

    A two-stage cascaded converter is formed by connecting two sub-converters in series. Output impedance of one sub-converter will therefore interact with input impedance of the other sub-converter. Such interaction may affect the system dynamics and stability, especially when one sub-converter is c......A two-stage cascaded converter is formed by connecting two sub-converters in series. Output impedance of one sub-converter will therefore interact with input impedance of the other sub-converter. Such interaction may affect the system dynamics and stability, especially when one sub......-converter is constant-power-controlled, and hence has different impedance characteristics when its power reverses. To lessen such constant-power effects, a control scheme that can coordinate impedance behaviors of the two sub-converters is proposed. The idea is to reshape the lowfrequency negative impedance...

  10. Hollow fiber based quantum cascade laser spectrometer for fast and sensitive drug identification

    Science.gov (United States)

    Herbst, J.; Scherer, B.; Ruf, A.; Erb, J.; Lambrecht, A.

    2012-01-01

    Sensitive and fast identification of drugs or drug precursors is important and necessary in scenarios like baggage or container check by customs or police. Fraunhofer IPM is developing a laser spectrometer using external cavity quantum cascade lasers (EC-QCL) to obtain mid-infrared (IR) absorption spectra in the wavelength range of the specific vibrational bands of amphetamines and their precursors. The commercial EC-QCL covers a tuning range of about 225 cm-1 within 1.4 s. The system could be used for different sample types like bulk samples or liquid solutions. A sampling unit evaporates the sample. Because of small sample amounts a 3 m long hollow fiber with an inner volume smaller than 1ml is used as gas cell and wave guide for the laser beam. This setup is suitable as a detector of a gas chromatograph instead of a standard detector (TCD or FID). The advantage is the selective identification of drugs by their IR spectra in addition to the retention time in the gas chromatographic column. In comparison to Fourier Transform IR systems the EC-QCL setup shows a good mechanical robustness and has the advantage of a point light source. Because of the good fiber incoupling performance of the EC-QCL it is possible to use hollow fibers. So, a good absorption signal is achieved because of the long optical path in the small cell volume without significant dilution. In first laboratory experiments a detection limit in the microgram range for pseudo ephedrine is achieved.

  11. [The application of laser in endodontics].

    Science.gov (United States)

    He, W X; Liu, N N; Wang, X L; He, X Y

    2016-08-01

    Since laser was introduced in the field of medicine in 1970's, its application range has continuously expanded. The application of laser in endodontics also increased due to its safety and effectiveness in dental treatments. The majority of the laser application researches in dentistry focused on dentin hypersensitivity, removal of carious tissues, tooth preparations, pulp capping or pulpotomy, and root canal treatment. In this article, we reviewed literature on the effects of laser in the treatments of dental and pulp diseases.

  12. Broadband mid-infrared and THz chemical detection with quantum cascade laser multi-heterodyne spectrometers (Conference Presentation)

    Science.gov (United States)

    Westberg, Jonas; Sterczewski, Lukasz A.; Patrick, Link; Wysocki, Gerard

    2017-05-01

    Majority of chemical species of interest in security and safety applications (e.g. explosives) have complex molecular structures that produce unresolved rotational-vibrational spectroscopic signatures in the mid-infrared. This requires spectroscopic techniques that can provide broadband coverage in the mid-IR region to target broadband absorbers and high resolution to address small molecules that exhibit well-resolved spectral lines. On the other hand, many broadband mid-IR absorbers exhibit well-resolved rotational components in the THz spectral region. Thus, development of spectroscopic sensing technologies that can address both spectral regions is of great importance. Here we demonstrate recent progress towards broadband high-resolution spectroscopic sensing applications with Fabry-Perot quantum cascade lasers (QCLs) and frequency combs using multi-heterodyne spectroscopy (MHS) techniques. In this paper, we will present spectroscopic sensing of large and small molecules in the mid-IR region using QCLs operating at 8.5µm. An example high-resolution, broadband MHS of ammonia (small molecule) and isobutane (broadband absorber) at atmospheric pressure in the 1165-1190 cm^-1 range will be discussed. We have developed a balanced MHS system for mitigation of the laser intensity fluctuations. Absorption spectroscopy as well as dispersion spectroscopy with minimum fractional absorption down to 10^-4/Hz1/2 and fast spectral acquisition capabilities down to 10 µs/spectrum range will be demonstrated. In order to mitigate the shortcomings of the limited chemical selectivity in the mid-IR, THz QCL based spectrometer is currently under development to provide spectral de-congestion and thus significantly improve chemical identification. Preliminary characterization of the performance of THZ QCL combs for the THz QCL-MHS will be presented.

  13. Tailored Ceramics for Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, Joel [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  14. Optical dynamics in low-dimensional semiconductor heterostructures. Quantum dots and quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Carsten

    2008-07-01

    This work is focused on the optical dynamics of mesoscopic semiconductor heterostructures, using as prototypes zero-dimensional quantum dots and quantum cascade lasers which consist of quasitwo- dimensional quantum wells. Within a density matrix theory, a microscopic many-particle theory is applied to study scattering effects in these structures: the coupling to external as well as local fields, electron-phonon coupling, coupling to impurities, and Coulomb coupling. For both systems, the investigated effects are compared to experimentally observed results obtained during the past years. In quantum dots, the three-dimensional spatial confinement leads to the necessity to consider a quantum kinetic description of the dynamics, resulting in non-Markovian electron-phonon effects. This can be seen in the spectral phonon sidebands due to interaction with acoustic phonons as well as a damping of nonlinear Rabi oscillations which shows a nonmonotonous intensity and pulse duration dependence. An analysis of the inclusion of the self-interaction of the quantum dot shows that no dynamical local field terms appear for the simple two-level model. Considering local fields which have their origin in many quantum dots, consequences for a two-level quantum dot such as a zero-phonon line broadening and an increasing signal in photon echo experiments are found. For the use of quantum dots in an optical spin control scheme, it is found that the dephasing due to the electron-phonon interaction can be dominant in certain regimes. Furthermore, soliton and breather solutions are studied analytically in nonlinear quantum dot ensembles. Generalizing to quasi-two-dimensional structures, the intersubband dynamics of quantum cascade laser structures is investigated. A dynamical theory is considered in which the temporal evolution of the subband populations and the current density as well as the influence of scattering effects is studied. In the nonlinear regime, the scattering dependence and

  15. Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

    Energy Technology Data Exchange (ETDEWEB)

    Lindskog, M., E-mail: martin.lindskog@teorfys.lu.se; Wacker, A. [Mathematical Physics, Lund University, Box 118, 22100 Lund (Sweden); Wolf, J. M.; Liverini, V.; Faist, J. [ETH Institute for Quantum Electronics, ETH-Zürich, 8093 Zürich (Switzerland); Trinite, V.; Maisons, G.; Carras, M. [III-V Lab, 1 Avenue Augustin Fresnel, 91767 Palaiseau (France); Aidam, R.; Ostendorf, R. [Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 72, 79108 Freiburg (Germany)

    2014-09-08

    We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents, agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device.

  16. Energy spectrum and thermal properties of a terahertz quantum-cascade laser based on the resonant-phonon depopulation scheme

    Energy Technology Data Exchange (ETDEWEB)

    Khabibullin, R. A., E-mail: khabibullin@isvch.ru; Shchavruk, N. V.; Klochkov, A. N.; Glinskiy, I. A.; Zenchenko, N. V.; Ponomarev, D. S.; Maltsev, P. P. [Russian Academy of Sciences, Institute of Ultrahigh Frequency Semiconductor Electronics (Russian Federation); Zaycev, A. A. [National Research University of Electronic Technology (MIET) (Russian Federation); Zubov, F. I.; Zhukov, A. E.; Cirlin, G. E.; Alferov, Zh. I. [Russian Academy of Sciences, Saint Petersburg Academic University—Nanotechnology Research and Education Center (Russian Federation)

    2017-04-15

    The dependences of the electronic-level positions and transition oscillator strengths on an applied electric field are studied for a terahertz quantum-cascade laser (THz QCL) with the resonant-phonon depopulation scheme, based on a cascade consisting of three quantum wells. The electric-field strengths for two characteristic states of the THz QCL under study are calculated: (i) “parasitic” current flow in the structure when the lasing threshold has not yet been reached; (ii) the lasing threshold is reached. Heat-transfer processes in the THz QCL under study are simulated to determine the optimum supply and cooling conditions. The conditions of thermocompression bonding of the laser ridge stripe with an n{sup +}-GaAs conductive substrate based on Au–Au are selected to produce a mechanically stronger contact with a higher thermal conductivity.

  17. Modeling of mid-infrared quantum cascade lasers: The role of temperature and operating field strength on the laser performance

    Science.gov (United States)

    Yousefvand, Hossein Reza

    2017-07-01

    In this paper a self-consistent numerical approach to study the temperature and bias dependent characteristics of mid-infrared (mid-IR) quantum cascade lasers (QCLs) is presented which integrates a number of quantum mechanical models. The field-dependent laser parameters including the nonradiative scattering times, the detuning and energy levels, the escape activation energy, the backfilling excitation energy and dipole moment of the optical transition are calculated for a wide range of applied electric fields by a self-consistent solution of Schrodinger-Poisson equations. A detailed analysis of performance of the obtained structure is carried out within a self-consistent solution of the subband population rate equations coupled with carrier coherent transport equations through the sequential resonant tunneling, by taking into account the temperature and bias dependency of the relevant parameters. Furthermore, the heat transfer equation is included in order to calculate the carrier temperature inside the active region levels. This leads to a compact predictive model to analyze the temperature and electric field dependent characteristics of the mid-IR QCLs such as the light-current (L-I), electric field-current (F-I) and core temperature-electric field (T-F) curves. For a typical mid-IR QCL, a good agreement was found between the simulated temperature-dependent L-I characteristic and experimental data, which confirms validity of the model. It is found that the main characteristics of the device such as output power and turn-on delay time are degraded by interplay between the temperature and Stark effects.

  18. Optical coatings for laser fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Lowdermilk, W.H.; Milam, D.; Rainer, F.

    1980-04-24

    Lasers for fusion experiments use thin-film dielectric coatings for reflecting, antireflecting and polarizing surface elements. Coatings are most important to the Nd:glass laser application. The most important requirements of these coatings are accuracy of the average value of reflectance and transmission, uniformity of amplitude and phase front of the reflected or transmitted light, and laser damage threshold. Damage resistance strongly affects the laser's design and performance. The success of advanced lasers for future experiments and for reactor applications requires significant developments in damage resistant coatings for ultraviolet laser radiation.

  19. Novel mid-infrared imaging system based on single-mode quantum cascade laser illumination and upconversion

    DEFF Research Database (Denmark)

    Tomko, Jan; Junaid, Saher; Tidemand-Lichtenberg, Peter

    2017-01-01

    Compared to the visible or near-infrared (NIR) spectral regions, there is a lack of very high sensitivity detectors in the mid-infrared (MIR) that operate near room temperature. Upconversion of the MIR light to NIR light that is imaged using affordable, fast, and sensitive NIR detectors or camera...... system based on upconversion technology with an external cavity quantum cascade laser (ECQCL) used as the illumination source....

  20. High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

    Science.gov (United States)

    Rao, Gottipaty N; Karpf, Andreas

    2010-09-10

    A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

  1. Laser applications in thin-film photovoltaics

    OpenAIRE

    Bartlome, R.; Strahm, B.; Sinquin, Y.; Feltrin, A.; Ballif, C.

    2009-01-01

    We review laser applications in thin-film photovoltaics (thin-film Si, CdTe, and Cu(In,Ga)Se2 solar cells). Lasers are applied in this growing field to manufacture modules, to monitor Si deposition processes, and to characterize opto-electrical properties of thin films. Unlike traditional panels based on crystalline silicon wafers, the individual cells of a thin-film photovoltaic module can be serially interconnected by laser scribing during fabrication. Laser scribing applications are descri...

  2. Efficient Detection of 3 THz Radiation from Quantum Cascade Laser Using Silicon CMOS Detectors

    Science.gov (United States)

    Ikamas, Kęstutis; Lisauskas, Alvydas; Boppel, Sebastian; Hu, Qing; Roskos, Hartmut G.

    2017-10-01

    In this paper, we report on efficient detection of the radiation emitted by a THz quantum cascade laser (QCL) using an antenna-coupled field effect transistor (TeraFET). In the limiting case when all radiated power would be collected, the investigated TeraFET can show up to 230 V/W responsivity with the noise equivalent power being as low as 85 pW/√ { {Hz}} at 3.1 THz, which is several times lower than that of the typical Golay cell. A combination of the QCL and a set of off-axis parabolic mirrors with 3-inch and 2-inch focal lengths was used to measure the signal-to-noise ratio (SNR) of the TeraFET. The practically achieved SNR was five times lower than that of the Golay cell and two orders of magnitude lower than a bolometer's. However, TeraFETs are much faster and do not need a signal modulation, thus can be used both in a continuous mode for power monitoring or for investigation of transient processes on a sub-microsecond time scale.

  3. Radiocarbon Dioxide detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

    CERN Document Server

    Genoud, Guillaume; Phillips, Hilary; Dean, Julian; Merimaa, Mikko

    2015-01-01

    Monitoring of radiocarbon ($^{14}$C) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardised sample containing elevated levels of radiocarbon. Radiocarbon dioxide could be detected from samples with an isotopic ratio $^{14}$C/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m$^3$ in pure CO$_2$, or 2 Bq/m$^3$ in air after extraction of the CO$_2$ from an air sample. The instrument is simple, compact and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring of radioactive gaseous emissions in nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.

  4. Quantum Transport Simulation of High-Power 4.6-μm Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Olafur Jonasson

    2016-06-01

    Full Text Available We present a quantum transport simulation of a 4.6- μ m quantum cascade laser (QCL operating at high power near room temperature. The simulation is based on a rigorous density-matrix-based formalism, in which the evolution of the single-electron density matrix follows a Markovian master equation in the presence of applied electric field and relevant scattering mechanisms. We show that it is important to allow for both position-dependent effective mass and for effective lowering of very thin barriers in order to obtain the band structure and the current-field characteristics comparable to experiment. Our calculations agree well with experiments over a wide range of temperatures. We predict a room-temperature threshold field of 62 . 5 kV/cm and a characteristic temperature for threshold-current-density variation of T 0 = 199 K . We also calculate electronic in-plane distributions, which are far from thermal, and show that subband electron temperatures can be hundreds to thousands of degrees higher than the heat sink. Finally, we emphasize the role of coherent tunneling current by looking at the size of coherences, the off-diagonal elements of the density matrix. At the design lasing field, efficient injection manifests itself in a large injector/upper lasing level coherence, which underscores the insufficiency of semiclassical techniques to address injection in QCLs.

  5. A Noninvasive In Vivo Glucose Sensor Based on Mid-Infrared Quantum Cascade Laser Spectroscopy

    Science.gov (United States)

    Werth, Alexandra; Liakat, Sabbir; Xu, Laura; Gmachl, Claire

    Diabetes affects over 387 million people worldwide; a number which grows every year. The most common method of measuring blood glucose concentration involves a finger prick which for some can be a harrowing process. Therefore, a portable, accurate, noninvasive glucose sensor can significantly improve the quality of life for many of these diabetics who draw blood multiple times a day to monitor their glucose levels. We have implemented a noninvasive, mobile glucose sensor using a mid-infrared (MIR) quantum cascade laser (QCL), integrating sphere, and thermal electrically (TE) cooled detector. The QCL is scanned from 8 - 10 microns wavelength over which are distinct absorption features of glucose molecules with little competition of absorption from other molecules found in the blood and interstitial fluid. The obtained absorption spectra are analyzed using a neural network algorithm which relates the small changes in absorption to the changing glucose concentration. The integrating sphere has increased the signal-to-noise ratio from a previous design, allowing us to use the TE-cooled detector which increases mobility without loss of accuracy.

  6. Study of the exhaled acetone in type 1 diabetes using quantum cascade laser spectroscopy.

    Science.gov (United States)

    Reyes-Reyes, Adonis; Horsten, Roland C; Urbach, H Paul; Bhattacharya, Nandini

    2015-01-06

    The acetone concentration exhaled in the breath of three type 1 diabetes patients (two minors and one adult) and one healthy volunteer is studied using a quantum cascade laser-based spectroscopic system. Using the acetone signature between 1150 and 1250 cm(-1) and a multiline fitting method, the concentration variations on the order of parts per billion by volume were measured. Blood glucose and ketone concentrations in blood measurements were performed simultaneously to study their relation with acetone in exhaled breath. We focus on personalized studies to better understand the role of acetone in diabetes. For each volunteer, we performed a series of measurements over a period of time, including overnight fastings of 11 ± 1 h and during ketosis-hyperglycemia events for the minors. Our results highlight the importance of performing personalized studies because the response of the minors to the presence of ketosis was consistent but unique for each individual. Also, our results emphasize the need for performing more studies with T1D minors, because the acetone concentration in the breath of the minors differs, with respect to those reported in the literature, which are based on adults.

  7. High Efficiency, Low Power-Consumption DFB Quantum Cascade Lasers Without Lateral Regrowth.

    Science.gov (United States)

    Jia, Zhi-Wei; Wang, Li-Jun; Zhang, Jin-Chuan; Liu, Feng-Qi; Zhou, Yu-Hong; Wang, Dong-Bo; Jia, Xue-Feng; Zhuo, Ning; Liu, Jun-Qi; Zhai, Shen-Qiang; Wang, Zhan-Guo

    2017-12-01

    Very low power-consumption distributed feedback (DFB) quantum cascade lasers (QCLs) at the wavelength around 4.9 μm were fabricated by conventional process without lateral regrowth of InP:Fe or using sidewall grating. Benefitted from the optimized materials and low waveguide loss, very low threshold current density of 0.5 kA/cm2 was obtained for a device with cavity length of 2 mm. Combined with the partial-high-reflection coating, the 1-mm-long DFB QCL achieved low power-consumption continuous wave (CW) operation up to 105 °C. The CW threshold power-consumptions were 0.72 and 0.78 W at 15 and 25 °C, respectively. The maximum CW output power was over 110 mW at 15 °C and still more than 35 mW at 105 °C. At 15 °C, wall-plug efficiency of 5.5% and slope efficiency of 1.8 W/A were deduced, which were very high for low power-consumption DFB QCLs.

  8. Room temperature negative differential resistance in terahertz quantum cascade laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Albo, Asaf, E-mail: asafalbo@gmail.com; Hu, Qing [Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Reno, John L. [Center for Integrated Nanotechnologies, Sandia National Laboratories, MS 1303, Albuquerque, New Mexico 87185-1303 (United States)

    2016-08-22

    The mechanisms that limit the temperature performance of GaAs/Al{sub 0.15}GaAs-based terahertz quantum cascade lasers (THz-QCLs) have been identified as thermally activated LO-phonon scattering and leakage of charge carriers into the continuum. Consequently, the combination of highly diagonal optical transition and higher barriers should significantly reduce the adverse effects of both mechanisms and lead to improved temperature performance. Here, we study the temperature performance of highly diagonal THz-QCLs with high barriers. Our analysis uncovers an additional leakage channel which is the thermal excitation of carriers into bounded higher energy levels, rather than the escape into the continuum. Based on this understanding, we have designed a structure with an increased intersubband spacing between the upper lasing level and excited states in a highly diagonal THz-QCL, which exhibits negative differential resistance even at room temperature. This result is a strong evidence for the effective suppression of the aforementioned leakage channel.

  9. Processing of AlGaAs/GaAs quantum-cascade structures for terahertz laser

    Science.gov (United States)

    Szerling, Anna; Kosiel, Kamil; Szymański, Michał; Wasilewski, Zbig; Gołaszewska, Krystyna; Łaszcz, Adam; Płuska, Mariusz; Trajnerowicz, Artur; Sakowicz, Maciej; Walczakowski, Michał; Pałka, Norbert; Jakieła, Rafał; Piotrowska, Anna

    2015-01-01

    We report research results with regard to AlGaAs/GaAs structure processing for THz quantum-cascade lasers (QCLs). We focus on the processes of Ti/Au cladding fabrication for metal-metal waveguides and wafer bonding with indium solder. Particular emphasis is placed on optimization of technological parameters for the said processes that result in working devices. A wide range of technological parameters was studied using test structures and the analysis of their electrical, optical, chemical, and mechanical properties performed by electron microscopic techniques, energy dispersive x-ray spectrometry, secondary ion mass spectroscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, and circular transmission line method. On that basis, a set of technological parameters was selected for the fabrication of devices lasing at a maximum temperature of 130 K from AlGaAs/GaAs structures grown by means of molecular beam epitaxy. Their resulting threshold-current densities were on a level of 1.5 kA/cm2. Furthermore, initial stage research regarding fabrication of Cu-based claddings is reported as these are theoretically more promising than the Au-based ones with regard to low-loss waveguide fabrication for THz QCLs.

  10. High-Resolution Infrared Spectroscopy of Imidazole Clusters in Helium Droplets Using Quantum Cascade Lasers

    Science.gov (United States)

    Mani, Devendra; Can, Cihad; Pal, Nitish; Schwaab, Gerhard; Havenith, Martina

    2017-06-01

    Imidazole ring is a part of many biologically important molecules and drugs. Imidazole monomer, dimer and its complexes with water have earlier been studied using infrared spectroscopy in helium droplets^{1,2} and molecular beams^{3}. These studies were focussed on the N-H and O-H stretch regions, covering the spectral region of 3200-3800 \\wn. We have extended the studies on imidazole clusters into the ring vibration region. The imidazole clusters were isolated in helium droplets and were probed using a combination of infrared spectroscopy and mass spectrometry. The spectra in the region of 1000-1100 \\wn and 1300-1460 \\wn were recorded using quantum cascade lasers. Some of the observed bands could be assigned to imidazole monomer and higher order imidazole clusters, using pickup curve analysis and ab initio calculations. Work is still in progress. The results will be discussed in detail in the talk. References: 1) M.Y. Choi and R.E. Miller, J. Phys. Chem. A, 110, 9344 (2006). 2) M.Y. Choi and R.E. Miller, Chem. Phys. Lett., 477, 276 (2009). 3) J. Zischang, J. J. Lee and M. Suhm, J. Chem. Phys., 135, 061102 (2011). Note: This work was supported by the Cluster of Excellence RESOLV (Ruhr-Universitat EXC1069) funded by the Deutsche Forschungsgemeinschaft.

  11. Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Gajić, A. [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Telekom Srbija, a.d., Takovska 2, 11000 Belgrade (Serbia); Radovanović, J., E-mail: radovanovic@etf.bg.ac.rs; Milanović, V. [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Indjin, D.; Ikonić, Z. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2014-02-07

    A computational model for the optimization of the second order optical nonlinearities in GaInAs/AlInAs quantum cascade laser structures is presented. The set of structure parameters that lead to improved device performance was obtained through the implementation of the Genetic Algorithm. In the following step, the linear and second harmonic generation power were calculated by self-consistently solving the system of rate equations for carriers and photons. This rate equation system included both stimulated and simultaneous double photon absorption processes that occur between the levels relevant for second harmonic generation, and material-dependent effective mass, as well as band nonparabolicity, were taken into account. The developed method is general, in the sense that it can be applied to any higher order effect, which requires the photon density equation to be included. Specifically, we have addressed the optimization of the active region of a double quantum well In{sub 0.53}Ga{sub 0.47}As/Al{sub 0.48}In{sub 0.52}As structure and presented its output characteristics.

  12. Standoff detection of turbulent chemical mixture plumes using a swept external cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C. [Pacific Northwest National Laboratory, Richland, Washington; Brumfield, Brian E. [Pacific Northwest National Laboratory, Richland, Washington

    2017-08-21

    We demonstrate standoff detection of turbulent mixed-chemical plumes using a broadly-tunable external cavity quantum cascade laser (ECQCL). The ECQCL was directed through plumes of mixed methanol/ethanol vapor to a partially-reflective surface located 10 m away. The reflected power was measured as the ECQCL was swept over its tuning range of 930-1065 cm-1 (9.4-10.8 µm) at rates up to 200 Hz. Analysis of the transmission spectra though the plume was performed to determine chemical concentrations with time resolution of 0.005 s. Comparison of multiple spectral sweep rates of 2 Hz, 20 Hz, and 200 Hz shows that higher sweep rates reduce effects of atmospheric and source turbulence, resulting in lower detection noise and more accurate measurement of the rapidly-changing chemical concentrations. Detection sensitivities of 0.13 ppm*m for MeOH and 1.2 ppm*m for EtOH are demonstrated for a 200 Hz spectral sweep rate, normalized to 1 s detection time.

  13. Quantum cascade laser-based sensor system for hydrogen peroxide detection

    Science.gov (United States)

    Ren, Wei; Jiang, Wenzhe; Sanchez, Nancy; Patimisco, Pietro; Spagnolo, Vincenzo; Zah, Chung-en; Xie, Feng; Hughes, Lawrence C.; Griffin, Robert J.; Tittel, Frank K.

    2013-12-01

    A quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor system was developed for the sensitive detection of hydrogen peroxide (H2O2) using its absorption transitions in the v6 fundamental band near 7.73 μm. The recent availability of distributed-feedback quantum cascade lasers (DFB-QCLs) provides convenient access to a strong H2O2 absorption line located at 1295.55 cm-1. Sensor calibration was performed by means of a water bubbler that generated titrated average vapor concentrations. A minimum detection limit of 75 parts per billion (ppb) was achieved at a pressure of 80 torr for a 1 sec data acquisition time. The long-term repeatability and stability of the sensor was investigated by measuring time-varying H2O2 mixtures for ~2 hrs. An Allan deviation analysis was performed to investigate the long-term performance of the QEPAS sensor system, indicating the feasibility of a minimum detection limit of 12 ppb using the optimum data averaging time of 100 sec.

  14. Regimes of external optical feedback in 5.6 μm distributed feedback mid-infrared quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jumpertz, L., E-mail: louise.jumpertz@telecom-paristech.fr [Telecom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 46 rue Barrault, 75013 Paris (France); Alcatel Thales III-V Lab, Campus de Polytechnique, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Carras, M. [Alcatel Thales III-V Lab, Campus de Polytechnique, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Schires, K.; Grillot, F. [Telecom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 46 rue Barrault, 75013 Paris (France)

    2014-09-29

    External optical feedback is studied experimentally in mid-infrared quantum cascade lasers. These structures exhibit a dynamical response close to that observed in interband lasers, with threshold reduction and optical power enhancement when increasing the feedback ratio. The study of the optical spectrum proves that the laser undergoes five distinct regimes depending on the phase and amplitude of the reinjected field. These regimes are mapped in the plane of external cavity length and feedback strength, revealing unstable behavior only for a very narrow range of operation, making quantum cascade lasers much more stable than their interband counterparts.

  15. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Babichev, A. V.; Karachinsky, L. Ya.; Novikov, I. I. [Ioffe Institute (Russian Federation); Nikitina, E. V. [St. Petersburg Academic University (Russian Federation); Tchernycheva, M. [University Paris Sud XI, Institut d’Electronique Fondamentale (France); Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Pikhtin, N. A.; Tarasov, I. S. [Ioffe Institute (Russian Federation)

    2015-11-15

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm{sup 2} at 220 K with the characteristic temperature T{sub 0} = 123 K was demonstrated.

  16. Measurement of Urban Air Quality by an Open-Path Quantum Cascade Laser Absorption Spectrometer in Beijing During Summer 2008

    Science.gov (United States)

    Michel, A. P.; Liu, P. Q.; Yeung, J. K.; Zhang, Y.; Baeck, M. L.; Pan, X.; Dong, H.; Wang, Z.; Smith, J. A.; Gmachl, C. F.

    2009-05-01

    The 2008 Olympic Games focused attention on the air quality of Beijing, China and served as an important test-bed for developing, deploying, and testing new technologies for analysis of air quality and regional climate in urban environments. Poor air quality in urban locations has a significant detrimental effect on the health of residents while also impacting both regional and global climate change. As a result, there exists a great need for highly sensitive trace gas sensors for studying the atmosphere of the urban environment. Open-path remote sensors are of particular interest as they can obtain data on spatial scales similar to those used in regional climate models. Quantum cascade lasers (QCLs) can be designed for operation in the mid-infrared (mid-IR) with a central wavelength anywhere between 3 to 24 μm and made tunable over a wavelength interval of over 0.1 μm. The Quantum Cascade Laser Open-Path System (QCLOPS) is a mid-infrared laser absorption spectrometer that uses a tunable, thermoelectrically cooled, pulsed Daylight Solutions Inc. QCL for measurement of trace gases. The system is aimed at applications with path lengths ranging from approximately 0.1 to 1.0 km. The system is designed to continuously monitor multiple trace gases [water vapor (H2O), ozone (O3), ammonia (NH3), and carbon dioxide (CO2)] in the lower atmosphere. A field campaign from July to September 2008 in Beijing used QCLOPS to study trace gas concentrations before, during, and after the Olympic Games in an effort to capture changes induced by emissions reduction methods. QCLOPS was deployed at the Institute of Atmospheric Physics - Chinese Academy of Sciences on the roof of a two-story building, at an approximate distance of 2 miles from the Olympic National Stadium ("The Bird's Nest.") QCLOPS operated with an open-path round trip distance of approximately 75 m. The system ran with minimal human interference, twenty-four hours per day for the full campaign period. In order to

  17. Unipolar GaAs AlGaAs mid infrared lasers for spectroscopic applications

    CERN Document Server

    Hvozdara, L

    2000-01-01

    100 mW per facet. The laser emission wavelengths range from 9.5 mu m to 13.2 mu m. The highest maximum operation temperature of T=230 K and the lowest threshold current density of 2.1 kA/cm sup 2 have been achieved among 14 samples presented in this work. A decrease of the threshold current by up to 40 % , and a slight increase of the highest operation temperature have been achieved by fabrication an air-semiconductor photonic bandgap mirror at the ends of a resonator. A FIB Cut coupled cavity quantum cascade laser has been designed and fabricated. An application of GaAs/AlGaAs quantum cascade lasers in the gas spectroscopy is demonstrated. The presented work was aimed to design and to study the electrical and optical properties of GaAs AlGaAs semiconductor heterostructures in order to develop novel coherent radiation sources for the mid infrared band. The main interest is focused on the experimental studies of quantum cascade emitters and lasers. The quantum cascade emitters and lasers are based on the intra...

  18. Unipolar GaAs AlGaAs mid infrared laser for spectroscopic applications

    CERN Document Server

    Hvozdara, L

    2000-01-01

    100 mW per facet. The laser emission wavelengths range from 9.5 mu m to 13.2 mu m. The highest maximum operation temperature of T=230 K and the lowest threshold current density of 2.1 kA/cm sup 2 have been achieved among 14 samples presented in this work. A decrease of the threshold current by up to 40 % , and a slight increase of the highest operation temperature have been achieved by fabrication an air-semiconductor photonic bandgap mirror at the ends of a resonator. A FIB Cut coupled cavity quantum cascade laser has been designed and fabricated. An application of GaAs/AlGaAs quantum cascade lasers in the gas spectroscopy is demonstrated. The presented work was aimed to design and to study the electrical and optical properties of GaAs AlGaAs semiconductor heterostructures in order to develop novel coherent radiation sources for the mid infrared band. The main interest is focused on the experimental studies of quantum cascade emitters and lasers. The quantum cascade emitters and lasers are based on the intra...

  19. Application of laser in obstetrics and gynecology

    Science.gov (United States)

    Ding, Ai-Hua

    1998-11-01

    Mainman developed the first ruby laser in 1960 and after 13 Kaplan successfully reported the use of CO2 laser in the treatment of cervicitis. Soon after, Chinese gynecologists started to use the laser for diagnosis and therapy. It had been proved that more than 30 kinds of gynecological diseases could be treated effectively by laser. The remarkable laser treatment technique partially replaced with conventional methods used in that century. However, the application of laser had shown a broad prospect along with its further investigation.

  20. Energy flow in a hadronic cascade: Application to hadroncalorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Groom, Donald E.

    2006-05-17

    The hadronic cascade description developed in an earlierpaper is extended to the response of an idealized fine-sampling hadroncalorimeter. Calorimeter response is largely determined by the transferof energy E_e from the hadronic to the electromagnetic sector via \\pi0production. Fluctuations in this quantity produce the "constant term" inhadron calorimeter resolution. The increase of its fractional mean, f_\\rmem^0= \\vevE_e/E, with increasing incident energy E causes the energydependence of the \\pi/e ratio in a noncompensating calorimeter. The meanhadronic energy fraction, f_h0 = 1-f_\\rm em0, was shown to scaleverynearly as a power law in E: f_h0 = (E/E_0)m-1, where E_0\\approx1~;GeV forpions, and m\\approx0.83. It follows that \\pi/e=1-(1-h/e)(E/E_0)m-1, whereelectromagnetic and hadronic energy deposits are detected withefficiencies e and h, respectively. Fluctuations in these quantities,along with sampling fluctuations, are in corporated to give an overallunderstanding of resolution, which is different from the usual treatmentsin interesting ways. The conceptual framework is also extended to theresponse to jets and the difference between pi and presponse.

  1. Laser technology and applications in gynaecology.

    Science.gov (United States)

    Adelman, M R; Tsai, L J; Tangchitnob, E P; Kahn, B S

    2013-04-01

    The term 'laser' is an acronym for Light Amplification by Stimulated Emission of Radiation. Lasers are commonly described by the emitted wavelength, which determines the colour of the light, as well as the active lasing medium. Currently, over 40 types of lasers have been developed with a wide range of both industrial and medical uses. Gas and solid-state lasers are frequently used in surgical applications, with CO2 and Ar being the most common examples of gas lasers, and the Nd:YAG and KTP:YAG being the most common examples of solid-state lasers. At present, it appears that the CO2, Nd:YAG, and KTP lasers provide alternative methods for achieving similar results, as opposed to superior results, when compared with traditional endoscopic techniques, such as cold-cutting monopolar and bipolar energy. This review focuses on the physics, tissue interaction, safety and applications of commonly used lasers in gynaecological surgery.

  2. Application of thermoluminescence for detection of cascade shower 1: Hardware and software of reader system

    Science.gov (United States)

    Akashi, M.; Kawaguchi, S.; Watanabe, Z.; Misaki, A.; Niwa, M.; Okamoto, Y.; Fujinaga, T.; Ichimura, M.; Shibata, T.; Dake, S.

    1985-01-01

    A reader system for the detection of cascade showers via luminescence induced by heating sensitive material (BaSO4:Eu) is developed. The reader system is composed of following six instruments: (1) heater, (2) light guide, (3) image intensifier, (4) CCD camera, (5) image processor, (6) microcomputer. The efficiency of these apparatuses and software application for image analysis is reported.

  3. High-energy molecular lasers self-controlled volume-discharge lasers and applications

    CERN Document Server

    Apollonov, V V

    2016-01-01

    This book displays the physics and design of high-power molecular lasers. The lasers described are self-controlled volume-discharge lasers. The book explains self-sustained discharge lasers, self-initiated discharge lasers and technical approaches to laser design. Important topics discussed are laser efficiency, laser beam quality and electric field homogeneity. The book contains many new innovative applications.

  4. Paediatric laser dentistry. Part 4: Soft tissue laser applications.

    Science.gov (United States)

    Olivi, G; Caprioglio, C; Olivi, M; Genovese, M D

    2017-12-01

    Lasers can provide effective soft tissues applications in children. All the wavelengths produce incision and vaporisation of oral tissues, together with a high bactericidal effect. The haemosthatic effect varys according to the wavelength used, and the choice of a visibile, near, medium or far infrared laser allows a better interaction with specific targets, gingiva, mucosa, frenum, or oral pathology.

  5. Three stage cascade diode lasers generating 500 mW near 3.2 μm

    Energy Technology Data Exchange (ETDEWEB)

    Hosoda, Takashi; Wang, Meng; Shterengas, Leon, E-mail: leon.shterengas@stonybrook.edu; Kipshidze, Gela; Belenky, Gregory [State University of New York at Stony Brook, Stony Brook, New York 11794 (United States)

    2015-09-14

    GaSb-based type-I quantum well 3.1–3.2 μm diode lasers with two- and three-cascade heterostructures were designed, fabricated, and characterized. Devices with ∼100-μm-wide aperture, 3-mm-long cavity, and anti-/high-reflection coated mirrors demonstrated continuous wave output power of 500 mW, threshold current density of ∼200 A/cm{sup 2}, and peak power conversion efficiency of ∼7% at 17 °C. This corresponds to more than twofold improvement in terms of output power and efficiency as compared to standard diode lasers operating in the same spectral region. The experiment showed that the increase in the number of cascades from two to three led to critical enhancement of the differential gain and reduction of the threshold current density. Light p-doping of the AlGaAsSb graded section did not introduce extra optical loss but aided hole transport as required for realization of the efficient multi-stage cascade pumping scheme.

  6. Three stage cascade diode lasers generating 500 mW near 3.2 μm

    Science.gov (United States)

    Hosoda, Takashi; Wang, Meng; Shterengas, Leon; Kipshidze, Gela; Belenky, Gregory

    2015-09-01

    GaSb-based type-I quantum well 3.1-3.2 μm diode lasers with two- and three-cascade heterostructures were designed, fabricated, and characterized. Devices with ˜100-μm-wide aperture, 3-mm-long cavity, and anti-/high-reflection coated mirrors demonstrated continuous wave output power of 500 mW, threshold current density of ˜200 A/cm2, and peak power conversion efficiency of ˜7% at 17 °C. This corresponds to more than twofold improvement in terms of output power and efficiency as compared to standard diode lasers operating in the same spectral region. The experiment showed that the increase in the number of cascades from two to three led to critical enhancement of the differential gain and reduction of the threshold current density. Light p-doping of the AlGaAsSb graded section did not introduce extra optical loss but aided hole transport as required for realization of the efficient multi-stage cascade pumping scheme.

  7. Quantum cascade laser-based multipass absorption system for hydrogen peroxide detection

    Science.gov (United States)

    Cao, Yingchun; Sanchez, Nancy P.; Jiang, Wenzhe; Ren, Wei; Lewicki, Rafal; Jiang, Dongfang; Griffin, Robert J.; Tittel, Frank K.

    2015-01-01

    Hydrogen peroxide (H2O2) is a relevant molecular trace gas species, that is related to the oxidative capacity of the atmosphere, the production of radical species such as OH, the generation of sulfate aerosol via oxidation of S(IV) to S(VI), and the formation of acid rain. The detection of atmospheric H2O2 involves specific challenges due to its high reactivity and low concentration (ppbv to sub-ppbv level). Traditional methods for measuring atmospheric H2O2 concentration are often based on wet-chemistry methods that require a transfer from the gas- to liquid-phase for a subsequent determination by techniques such as fluorescence spectroscopy, which can lead to problems such as sampling artifacts and interference by other atmospheric constituents. A quartz-enhanced photoacoustic spectroscopy-based system for the measurement of atmospheric H2O2 with a detection limit of 75 ppb for 1-s integration time was previously reported. In this paper, an updated H2O2 detection system based on long-optical-path-length absorption spectroscopy by using a distributed feedback quantum cascade laser (DFB-QCL) will be described. A 7.73-μm CW-DFB-QCL and a thermoelectrically cooled infrared detector, optimized for a wavelength of 8 μm, are employed for theH2O2 sensor system. A commercial astigmatic Herriott multi-pass cell with an effective optical path-length of 76 m is utilized for the reported QCL multipass absorption system. Wavelength modulation spectroscopy (WMS) with second harmonic detection is used for enhancing the signal-to-noise-ratio. A minimum detection limit of 13.4 ppb is achieved with a 2 s sampling time. Based on an Allan-Werle deviation analysis the minimum detection limit can be improved to 1.5 ppb when using an averaging time of 300 s.

  8. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    Science.gov (United States)

    Gerdel, Katharina; Spielmann, Felix Maximilian; Hammerle, Albin; Wohlfahrt, Georg

    2017-09-01

    The trace gas carbonyl sulfide (COS) has lately received growing interest from the eddy covariance (EC) community due to its potential to serve as an independent approach for constraining gross primary production and canopy stomatal conductance. Thanks to recent developments of fast-response high-precision trace gas analysers (e.g. quantum cascade laser absorption spectrometers, QCLAS), a handful of EC COS flux measurements have been published since 2013. To date, however, a thorough methodological characterisation of QCLAS with regard to the requirements of the EC technique and the necessary processing steps has not been conducted. The objective of this study is to present a detailed characterisation of the COS measurement with the Aerodyne QCLAS in the context of the EC technique and to recommend best EC processing practices for those measurements. Data were collected from May to October 2015 at a temperate mountain grassland in Tyrol, Austria. Analysis of the Allan variance of high-frequency concentration measurements revealed the occurrence of sensor drift under field conditions after an averaging time of around 50 s. We thus explored the use of two high-pass filtering approaches (linear detrending and recursive filtering) as opposed to block averaging and linear interpolation of regular background measurements for covariance computation. Experimental low-pass filtering correction factors were derived from a detailed cospectral analysis. The CO2 and H2O flux measurements obtained with the QCLAS were compared with those obtained with a closed-path infrared gas analyser. Overall, our results suggest small, but systematic differences between the various high-pass filtering scenarios with regard to the fraction of data retained in the quality control and flux magnitudes. When COS and CO2 fluxes are combined in the ecosystem relative uptake rate, systematic differences between the high-pass filtering scenarios largely cancel out, suggesting that this relative metric

  9. Real time detection of exhaled human breath using quantum cascade laser based sensor technology

    Science.gov (United States)

    Tittel, Frank K.; Lewicki, Rafal; Dong, Lei; Liu, Kun; Risby, Terence H.; Solga, Steven; Schwartz, Tim

    2012-02-01

    The development and performance of a cw, TE-cooled DFB quantum cascade laser based sensor for quantitative measurements of ammonia (NH3) and nitric oxide (NO) concentrations present in exhaled breath will be reported. Human breath contains ~ 500 different chemical species, usually at ultra low concentration levels, which can serve as biomarkers for the identification and monitoring of human diseases or wellness states. By monitoring NH3 concentration levels in exhaled breath a fast, non-invasive diagnostic method for treatment of patients with liver and kidney disorders, is feasible. The NH3 concentration measurements were performed with a 2f wavelength modulation quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is suitable for real time breath measurements, due to the fast gas exchange inside a compact QEPAS gas cell. A Hamamatsu air-cooled high heat load (HHL) packaged CW DFB-QCL is operated at 17.5°C, targeting the optimum interference free NH3 absorption line at 967.35 cm-1 (λ~10.34 μm), with ~ 20 mW of optical power. The sensor architecture includes a reference cell, filled with a 2000 ppmv NH3 :N2 mixture at 130 Torr, which is used for absorption line-locking. A minimum detection limit (1σ) for the line locked NH3 sensor is ~ 6 ppbv (with a 1σ 1 sec time resolution of the control electronics). This NH3 sensor was installed in late 2010 and is being clinically tested at St. Luke's Hospital in Bethlehem, PA.

  10. Optimization of a 3.6-THz quantum cascade laser for real-time imaging with a microbolometer focal plane array

    Science.gov (United States)

    Behnken, Barry N.; Karunasiri, Gamani; Chamberlin, Danielle; Robrish, Peter; Faist, Jérôme

    2008-02-01

    Real-time imaging in the terahertz (THz) spectral range was achieved using a 3.6-THz quantum cascade laser (QCL) and an uncooled, 160×120 pixel microbolometer camera fitted with a picarin lens. Noise equivalent temperature difference of the camera in the 1-5 THz frequency range was calculated to be at least 3 K, confirming the need for external THz illumination when imaging in this frequency regime. After evaluating the effects of various operating parameters on laser performance, the QCL found to perform optimally at 1.9 A in pulsed mode with a 300 kHz repetition rate and 10-20% duty cycle; average output power was approximately 1 mW. Under this scheme, a series of metallic objects were imaged while wrapped in various obscurants. Single-frame and extended video recordings demonstrate strong contrast between metallic materials and those of plastic, cloth, and paper - supporting the viability of this imaging technology in security screening applications. Thermal effects arising from Joule heating of the laser were found to be the dominant issue affecting output power and image quality; these effects were mitigated by limiting laser pulse widths to 670 ns and operating the system under closed-cycle refrigeration at a temperature of 10 K.

  11. Dye laser principles with applications

    CERN Document Server

    Duarte, Frank J; Liao, Peter F; Kelley, Paul

    1990-01-01

    A tutorial introduction to the field of dye lasers, Dye Laser Principles also serves as an up-to-date overview for those using dye lasers as research and industrial tools. A number of the issues discussed in this book are pertinent not only to dye lasers but also to lasers in general. Most of the chapters in the book contain problem sets that expand on the material covered in the chapter.Key Features* Dye lasers are among the most versatile and successful laser sources currently available in use Offering both pulsed and continuous-wave operation and tunable from the near ultraviole

  12. Femtosecond Laser Ablation: Fundamentals and Applications

    Science.gov (United States)

    Harilal, Sivanandan S.; Freeman, Justin R.; Diwakar, Prasoon K.; Hassanein, Ahmed

    Traditionally nanosecond laser pulses have been used for Laser-induced Breakdown Spectroscopy (LIBS) for quantitative and qualitative analysis of the samples. Laser produced plasmas using nanosecond laser pulses have been studied extensively since 1960s. With the advent of short and ultrashort laser pulses, there has been a growing interest in the applications of femtosecond and picosecond lasers for analysis of materials using LIBS and LA-ICP-MS. The fundamentals of laser ablation process using ultrashort laser pulses are not still fully understood. Pulse duration of femtosecond laser pulse is shorter than electron-to-ion energy transfer time and heat conduction time in the sample lattice. This results in different laser ablation and heat dissipation mechanisms as compared to nanosecond laser ablation. In this chapter, the focus will be on understanding the basics of femtosecond laser ablation processes including laser target interaction, ablation efficiency, ablation threshold, laser plasma interactions, and plume hydrodynamics. Analytical figures of merit will be discussed in contrast to nanosecond LIBS.

  13. The SMAT fiber laser for industrial applications

    Science.gov (United States)

    Ding, Jianwu; Liu, Jinghui; Wei, Xi; Xu, Jun

    2017-02-01

    With the increased adoption of high power fiber laser for various industrial applications, the downtime and the reliability of fiber lasers become more and more important. Here we present our approach toward a more reliable and more intelligent laser source for industrial applications: the SMAT fiber laser with the extensive sensor network and multi-level protection mechanism, the mobile connection and the mobile App, and the Smart Cloud. The proposed framework is the first IoT (Internet of Things) approach integrated in an industrial laser not only prolongs the reliability of an industrial laser but open up enormous potential for value-adding services by gathering and analyzing the Big data from the connected SMAT lasers.

  14. Short pulse laser systems for biomedical applications

    CERN Document Server

    Mitra, Kunal

    2017-01-01

    This book presents practical information on the clinical applications of short pulse laser systems and the techniques for optimizing these applications in a manner that will be relevant to a broad audience, including engineering and medical students as well as researchers, clinicians, and technicians. Short pulse laser systems are useful for both subsurface tissue imaging and laser induced thermal therapy (LITT), which hold great promise in cancer diagnostics and treatment. Such laser systems may be used alone or in combination with optically active nanoparticles specifically administered to the tissues of interest for enhanced contrast in imaging and precise heating during LITT. Mathematical and computational models of short pulse laser-tissue interactions that consider the transient radiative transport equation coupled with a bio-heat equation considering the initial transients of laser heating were developed to analyze the laser-tissue interaction during imaging and therapy. Experiments were first performe...

  15. Laser technology in biomimetics basics and applications

    CERN Document Server

    Belegratis, Maria

    2013-01-01

    Lasers are progressively more used as versatile tools for fabrication purposes. The wide range of available powers, wavelengths, operation modes, repetition rates etc. facilitate the processing of a large spectrum of materials at exceptional precision and quality. Hence, manifold methods were established in the past and novel methods are continuously under development. Biomimetics, the translation from nature-inspired principles to technical applications, is strongly multidisciplinary. This field offers intrinsically a wide scope of applications for laser based methods regarding structuring and modification of materials. This book is dedicated to laser fabrication methods in biomimetics. It introduces both, a laser technology as well as an application focused approach.  The book covers the most important laser lithographic methods and various biomimetics application scenarios ranging from coatings and biotechnology to construction, medical applications and photonics.

  16. Selective ablation of WHHLMI rabbit atherosclerotic plaque by quantum cascade laser in the 5.7 μm wavelength range for less-invasive laser angioplasty

    Science.gov (United States)

    Hashimura, Keisuke; Ishii, Katsunori; Akikusa, Naota; Edamura, Tadataka; Yoshida, Harumasa; Awazu, Kunio

    2013-06-01

    We investigated the potential of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques consist mainly of cholesteryl esters. Radiation at a wavelength of 5.75 μm is strongly absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal artery and an atherosclerotic lesions using nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For applying this technique to clinical treatment, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. Subsequently, QCL irradiation effects on an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal rabbit aorta were observed. As a result, the QCL could make cutting differences between the rabbit atherosclerotic and normal aortas. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depths. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.

  17. A review of energy bandgap engineering in III V semiconductor alloys for mid-infrared laser applications

    Science.gov (United States)

    Yin, Zongyou; Tang, Xiaohong

    2007-01-01

    Semiconductor lasers emitting in mid-infrared (IR) range, 2-5 μm, have many important applications in semiconductor industries, military, environmental protection, telecommunications, molecular spectroscopy, biomedical surgery and researches. Different designs of the reactive regions in mid-IR laser structures have been investigated for achieving high performance devices. In this article, semiconductor mid-IR lasers with double heterostructure, quantum well, quantum cascade, quantum wire, quantum dash and quantum dot active regions have been reviewed. The performance of the lasers with these different active regions and the development of the newly emerging III-V-N materials for mid-IR applications have been discussed in details.

  18. Safe laser application requires more than laser safety

    Science.gov (United States)

    Frevel, A.; Steffensen, B.; Vassie, L.

    1995-02-01

    An overview is presented concerning aspects of laser safety in European industrial laser use. Surveys indicate that there is a large variation in the safety strategies amongst industrial laser users. Some key problem areas are highlighted. Emission of hazardous substances is a major problem for users of laser material processing systems where the majority of the particulate is of a sub-micrometre size, presenting a respiratory hazard. Studies show that in many cases emissions are not frequently monitored in factories and uncertainty exists over the hazards. Operators of laser machines do not receive adequate job training or safety training. The problem is compounded by a plethora of regulations and standards which are difficult to interpret and implement, and inspectors who are not conversant with the technology or the issues. A case is demonstrated for a more integrated approach to laser safety, taking into account the development of laser applications, organizational and personnel development, in addition to environmental and occupational health and safety aspects. It is necessary to achieve a harmonization between these elements in any organization involved in laser technology. This might be achieved through establishing technology transfer centres in laser technology.

  19. Design of chirped distributed Bragg reflector for octave-spanning frequency group velocity dispersion compensation in terahertz quantum cascade laser.

    Science.gov (United States)

    Xu, Chao; Ban, Dayan

    2016-06-13

    The strategies and approaches of designing chirped Distributed Bragg Reflector for group velocity compensation in metal-metal waveguide terahertz quantum cascade laser are investigated through 1D and 3D models. The results show the depth of the corrugation periods plays an important role on achieving broad-band group velocity compensation in terahertz range. However, the deep corrugation also brings distortion to the group delay behavior. A two-section chirped DBR is proposed to provide smoother group delay compensation while still maintain the broad frequency range (octave) operation within 2 THz to 4 THz.

  20. Multiple lobes in the far-field distribution of terahertz quantum-cascade lasers due to self-interference

    Directory of Open Access Journals (Sweden)

    B. Röben

    2016-06-01

    Full Text Available The far-field distribution of the emission intensity of terahertz (THz quantum-cascade lasers (QCLs frequently exhibits multiple lobes instead of a single-lobed Gaussian distribution. We show that such multiple lobes can result from self-interference related to the typically large beam divergence of THz QCLs and the presence of an inevitable cryogenic operation environment including optical windows. We develop a quantitative model to reproduce the multiple lobes. We also demonstrate how a single-lobed far-field distribution can be achieved.

  1. Chalcogenide glass waveguides integrated with quantum cascade lasers for on-chip mid-IR photonic circuits.

    Science.gov (United States)

    Tsay, Candice; Toor, Fatima; Gmachl, Claire F; Arnold, Craig B

    2010-10-15

    We demonstrate on-chip hybrid integration of chalcogenide glass waveguides and quantum cascade lasers (QCLs). Integration is achieved using an additive solution-casting and molding method to directly form As(2)S(3) strip waveguides on an existing QCL chip. Integrated As(2)S(3) strip waveguides constructed in this manner display strong optical confinement and guiding around 90° bends, with a NA of 0.24 and bend loss of 12.9dB at a 1mm radius (λ=4.8μm).

  2. Fiber lasers and their applications [Invited].

    Science.gov (United States)

    Shi, Wei; Fang, Qiang; Zhu, Xiushan; Norwood, R A; Peyghambarian, N

    2014-10-01

    Fiber lasers have seen progressive developments in terms of spectral coverage and linewidth, output power, pulse energy, and ultrashort pulse width since the first demonstration of a glass fiber laser in 1964. Their applications have extended into a variety of fields accordingly. In this paper, the milestones of glass fiber laser development are briefly reviewed and recent advances of high-power continuous wave, Q-switched, mode-locked, and single-frequency fiber lasers in the 1, 1.5, 2, and 3 μm regions and their applications in such areas as industry, medicine, research, defense, and security are addressed in detail.

  3. Gas chromatography vs. quantum cascade laser-based N2O flux measurements using a novel chamber design

    Science.gov (United States)

    Brümmer, Christian; Lyshede, Bjarne; Lempio, Dirk; Delorme, Jean-Pierre; Rüffer, Jeremy J.; Fuß, Roland; Moffat, Antje M.; Hurkuck, Miriam; Ibrom, Andreas; Ambus, Per; Flessa, Heinz; Kutsch, Werner L.

    2017-03-01

    Recent advances in laser spectrometry offer new opportunities to investigate the soil-atmosphere exchange of nitrous oxide. During two field campaigns conducted at a grassland site and a willow field, we tested the performance of a quantum cascade laser (QCL) connected to a newly developed automated chamber system against a conventional gas chromatography (GC) approach using the same chambers plus an automated gas sampling unit with septum capped vials and subsequent laboratory GC analysis. Through its high precision and time resolution, data of the QCL system were used for quantifying the commonly observed nonlinearity in concentration changes during chamber deployment, making the calculation of exchange fluxes more accurate by the application of exponential models. As expected, the curvature values in the concentration increase was higher during long (60 min) chamber closure times and under high-flux conditions (FN2O > 150 µg N m-2 h-1) than those values that were found when chambers were closed for only 10 min and/or when fluxes were in a typical range of 2 to 50 µg N m-2 h-1. Extremely low standard errors of fluxes, i.e., from ˜ 0.2 to 1.7 % of the flux value, were observed regardless of linear or exponential flux calculation when using QCL data. Thus, we recommend reducing chamber closure times to a maximum of 10 min when a fast-response analyzer is available and this type of chamber system is used to keep soil disturbance low and conditions around the chamber plot as natural as possible. Further, applying linear regression to a 3 min data window with rejecting the first 2 min after closure and a sampling time of every 5 s proved to be sufficient for robust flux determination while ensuring that standard errors of N2O fluxes were still on a relatively low level. Despite low signal-to-noise ratios, GC was still found to be a useful method to determine the mean the soil-atmosphere exchange of N2O on longer timescales during specific campaigns. Intriguingly

  4. Integrated Applications with Laser Technology

    Directory of Open Access Journals (Sweden)

    Octavian DOSPINESCU

    2013-01-01

    Full Text Available The introduction of new materials as Power Point presentations are the most convenient way of teaching a course or to display a scientific paper. In order to support this function, most schools, universities, institutions, are equipped with projectors and computers. For controlling the presentation of the materials, the persons that are in charge with the presentation use, in most cases, both the keyboard of the computer as well as the mouse for the slides, thing that burdens, in a way, the direct communication (face to face with the audience. Of course, the invention of the wireless mouse allowed a sort of freedom in controlling from the distance the digital materials. Although there seems to appear a certain impediment: in order to be used, the mouse requires to be placed on a flat surface. This article aims at creating a new application prototype that will manipulate, only through the means of a light-beam instrument (laser fascicle, both the actions of the mouse as well as some of the elements offered by the keyboard on a certain application or presentation. The light fascicle will be „connected” to a calculus system only through the images that were captured by a simple webcam.

  5. Laser-plasma interactions and applications

    CERN Document Server

    Neely, David; Bingham, Robert; Jaroszynski, Dino

    2013-01-01

    Laser-Plasma Interactions and Applications covers the fundamental and applied aspects of high power laser-plasma physics. With an internationally renowned team of authors, the book broadens the knowledge of young researchers working in high power laser-plasma science by providing them with a thorough pedagogical grounding in the interaction of laser radiation with matter, laser-plasma accelerators, and inertial confinement fusion. The text is organised such that the theoretical foundations of the subject are discussed first, in Part I. In Part II, topics in the area of high energy density physics are covered. Parts III and IV deal with the applications to inertial confinement fusion and as a driver of particle and radiation sources, respectively. Finally, Part V describes the principle diagnostic, targetry, and computational approaches used in the field. This book is designed to give students a thorough foundation in the fundamental physics of laser-plasma interactions. It will also provide readers with knowl...

  6. Applications of gamma-ray lasers

    Science.gov (United States)

    Balko, B.; Cohen, L.; Hartmann, F. X.

    1985-11-01

    As a result of the IST/IDA Gamma-Ray Laser Workshop held in May 1985, a general picture of the gamma-ray laser has emerged. The characteristics of the radiation from this source are contrasted with those from other coherent sources; these include energy, bandwidth, intensity, and coherence length. Potential nonmilitary applications are listed; and two classes of military applications are suggested. Those characteristics which drive a specific application are spelled out.

  7. Frequency locking of an extended-cavity quantum cascade laser to a frequency comb for precision mid infrared spectroscopy

    KAUST Repository

    Alsaif, Bidoor

    2017-11-02

    Extended-cavity quantum cascade lasers (EC-QCLs) enable mode-hope-free frequency sweeps in the mid-infrared region over ranges in excess of 100 cm−1, at speeds up to 1 THz/s and with a 100-mW optical power level. This makes them ideally suited for broadband absorption spectroscopy and for the simultaneous detection of multiple gases. On the other hand, their use for precision spectroscopy has been hampered so far by a large amount of frequency noise, resulting in an optical linewidth of about 30 MHz over 50 ms [1]. This is one of the reasons why neither their frequency nor their phase have been so far locked to a frequency comb. Their use in combination with frequency combs has been performed in an open loop regime only [2], which has the merit of preserving the inherently fast modulation speed of these lasers, yet not to afford high spectral resolution and accuracy.

  8. Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gangyi, E-mail: gangyi.xu@mail.sitp.ac.cn [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Lianhe; Giles Davies, A.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS9 2JT (United Kingdom); Isac, Nathalie; Halioua, Yacine; Colombelli, Raffaele, E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France)

    2014-03-03

    We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

  9. Temperature induced degradation mechanisms of AlInAs/InGaAs/InP quantum cascade lasers

    Science.gov (United States)

    Pierścińska, D.; Pierściński, K.; Płuska, M.; Sobczak, G.; Kuźmicz, A.; Gutowski, P.; Bugajski, M.

    2018-01-01

    In this paper, we report on the investigation of temperature induced degradation mode of quantum cascade lasers (QCLs) with an emphasis on the influence of different processing technology. We investigate and compare lattice matched AlInAs/InGaAs/InP QCLs of various constructions, i.e., double trench, buried heterostructure and ridge waveguide regarding thermal management, reliability and sources of degradation. The analysis was performed by CCD thermoreflectance spectroscopy, scanning electron microscope inspection and destructive analysis by focused ion beam etching, enabling determination of the source and mode of degradation for investigated lasers. Experimental temperature data relate temperature rise, arising from supply current, with device geometry. Results clearly indicate, that the buried heterostructure geometry, allows reaching the highest maximal operating current densities, before the degradation occurs. Microscopic images of degradation confirm that degradation includes the damage of the contact layer as well as damage of the active region layers.

  10. QEPAS based detection of broadband absorbing molecules using a widely tunable, cw quantum cascade laser at 8.4 mum.

    Science.gov (United States)

    Lewicki, Rafal; Wysocki, Gerard; Kosterev, Anatoliy A; Tittel, Frank K

    2007-06-11

    Detection of molecules with wide unresolved rotationa-lvibrational absorption bands is demonstrated by using Quartz Enhanced Photoacoustic Spectroscopy and an amplitude modulated, high power, thermoelectrically cooled quantum cascade laser operating at 8.4 mum in an external cavity configuration. The laser source exhibits single frequency tuning of 135 cm-1 with a maximum optical output power of 50 mW. For trace-gas detection of Freon 125 (pentafluoroethane) at 1208.62 cm-1 a normalized noise equivalent absorption coefficient of NNEA=2.64x10(-9) cm?(-1)W/Hz(1/2)was obtained. Noise equivalent sensitivity at ppbv level as well as spectroscopic chemical analysis of a mixture of two broadband absorbers (Freon 125 and acetone) with overlapping absorption spectra were demonstrated.

  11. High-precision molecular interrogation by direct referencing of a quantum-cascade-laser to a near-infrared frequency comb.

    Science.gov (United States)

    Gatti, D; Gambetta, A; Castrillo, A; Galzerano, G; Laporta, P; Gianfrani, L; Marangoni, M

    2011-08-29

    This work presents a very simple yet effective way to obtain direct referencing of a quantum-cascade-laser at 4.3 μm to a near-IR frequency-comb. Precise tuning of the comb repetition-rate allows the quantum-cascade-laser to be scanned across absorption lines of a CO2 gaseous sample and line profiles to be acquired with extreme reproducibility and accuracy. By averaging over 50 acquisitions, line-centre frequencies are retrieved with an uncertainty of 30 kHz in a linear interaction regime. The extension of this methodology to other lines and molecules, by the use of widely tunable extended-cavity quantum-cascade-lasers, paves the way to a wide availability of high-quality and traceable spectroscopic data in the most crucial region for molecular detection and interrogation.

  12. Measurement of nitrous acid (HONO) by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    Science.gov (United States)

    Yi, Hongming; Maamary, Rabih; Gao, Xiaoming; Sigrist, Markus W.; Fertein, Eric; Chen, Weidong

    2016-04-01

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm-1 was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ~40 mm3) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by simultaneous measurements of direct HONO absorption spectra in a 109.5 m multipass cell using a distributed feedback (DBF) QCL. A minimum detection limit (MDL @ SNR=1) of 66 ppbv HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6×10-8 cm-1.W/Hz1/2. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding minimum detected absorption coefficient (SNR=1) is ~1.1×10-7 cm-1 (MDL: ~3 ppbv) in 1 s and ~1.1×10-8 cm-1 (MDL~330 pptv) in 150 s, respectively, with 1 W laser power. Acknowledgements The authors acknowledge financial supports from the CaPPA project (ANR-10-LABX-005) and the CPER CLIMIBIO program. References H. Yi, R. Maamary, X. Gao, M. W. Sigrist, E. Fertein, W. Chen, "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106 (2015) 101109

  13. A CMOS DCCII with a Grounded Capacitor Based Cascadable All-Pass Filter Application

    Directory of Open Access Journals (Sweden)

    B. Metin

    2012-06-01

    Full Text Available The differential current conveyor (DCCII is a versatile current-mode active element, which has a current differencing capability. In this study, a new CMOS DCCII implementation is introduced. As an application example, a novel voltage-mode (VM first-order all-pass filter (APF is presented. The proposed VM APF employs two resistors, grounded capacitor and has high-input impedance for cascadability. Simulation and experimental results are given to verify the operation of the circuit.

  14. Anti-Stokes scattering and Stokes scattering of stimulated Brillouin scattering cascade in high-intensity laser-plasmas interaction

    Science.gov (United States)

    Feng, Qingsong; Zheng, Chunyang; Liu, Zhanjun; Xiao, Chengzhuo; Wang, Qing; Cao, Lihua; He, Xiantu

    2017-10-01

    The anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascade have been researched by the Vlasov-Maxwell simulation. In the high-intensity laser-plasmas interaction, the stimulated anti-Stokes Brillouin scattering (SABS) will occur after the second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. In the early time of SBS evolution, only the first stage SBS appears, and the total SBS reflectivity comes from the first stage SBS. However, when the high-stage SBS and SABS occur, the SBS reflectivity will appear a burst behavior, and the total reflectivity comes from the SBS cascade and SABS superimposition. The SABS will compete with the SBS rescattering to determine the total SBS reflectivity. Thus, the SBS rescattering including the SABS is an important saturation mechanism of SBS, and should be taken into account in the high-intensity laser-plasmas interaction. This research was supported by the National Natural Science Foundation of China (Grant Nos. 11375032, 11575035, 11475030 and 11435011), National Basic Research Program of China (Grant No. 2013CB834101) and Science Challenge Project, No. TZ2016005.

  15. Applications of laser ablation to microengineering

    Science.gov (United States)

    Gower, Malcolm C.; Rizvi, Nadeem H.

    2000-08-01

    Applications of pulsed laser ablation to the manufacture of micro- electro-mechanical systems (MEMS) and micro-opto-electro-mechanical systems (MOEMS) devices are presented. Laser ablative processes used to manufacture a variety of microsystems technology (MST) components in the computer peripheral, sensing and biomedical industries are described together with a view of some future developments.

  16. Laser applications in nuclear power plants

    Indian Academy of Sciences (India)

    2014-01-09

    Jan 9, 2014 ... Abstract. This paper reports the state of the art of using a solid-state Nd:YAG laser for material processing applications such as cutting, welding and drilling of several components of operational nuclear reactors in radioactive environment. We have demonstrated several advantages of laser- based material ...

  17. Spectral modification of the laser emission of a terahertz quantum cascade laser induced by broad-band double pulse injection seeding

    Energy Technology Data Exchange (ETDEWEB)

    Markmann, Sergej, E-mail: sergej.markmann@ruhr-uni-bochum.de; Nong, Hanond, E-mail: nong.hanond@ruhr-uni-bochum.de; Hekmat, Negar; Jukam, Nathan [AG Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Pal, Shovon [AG Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Scholz, Sven; Kukharchyk, Nadezhda; Ludwig, Arne; Wieck, Andreas D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Dhillon, Sukhdeep; Tignon, Jérôme [Laboratoire Pierre Aigrain, Ecole Normale Supérieure, UMR 8551 CNRS, UPMC, Univ. Paris 6, 75005 Paris (France); Marcadet, Xavier [Alcatel-Thales III-V Lab, Route Départementale 128, 91767 Palaiseau Cedex (France); Bock, Claudia; Kunze, Ulrich [Lehrstuhl für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2015-09-14

    We demonstrate by injection seeding that the spectral emission of a terahertz (THz) quantum cascade laser (QCL) can be modified with broad-band THz pulses whose bandwidths are greater than the QCL bandwidth. Two broad-band THz pulses delayed in time imprint a modulation on the single THz pulse spectrum. The resulting spectrum is used to injection seed the THz QCL. By varying the time delay between the THz pulses, the amplitude distribution of the QCL longitudinal modes is modified. By applying this approach, the QCL emission is reversibly switched from multi-mode to single mode emission.

  18. Physics and Applications of Laser Diode Chaos

    CERN Document Server

    Sciamanna, Marc

    2015-01-01

    An overview of chaos in laser diodes is provided which surveys experimental achievements in the area and explains the theory behind the phenomenon. The fundamental physics underpinning this behaviour and also the opportunities for harnessing laser diode chaos for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient test-bed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.

  19. Laser Applications in Flow Diagnostics

    Science.gov (United States)

    1988-10-01

    coherent structures in a high-speed exhaust jet," ISL - CO 209/82. 4.79 NASA Conference Publication No. 2393, "Wind Tunnel Seed Systems for Laser...20 (1985). 174 Hunter. W. W. and Nichols, C. E.. "Wind Tunnel Seed Systems for Laser Velocimeters," NASA Conference Publication No. 2393, Langley

  20. High-power 1.9-3.3-μm type-I quantum-well cascade diode lasers

    Science.gov (United States)

    Shterengas, L.; Hosoda, T.; Wang, M.; Feng, T.; Kipshidze, G.; Belenky, G.

    2017-02-01

    Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in spectral region from 1.9 to 3.3 μm. Two-step ridge waveguide design with shallow 5-μm-wide and deep 15-μm-wide etched sections yielded λ 2 μm lasers generating 250 mW of continuous wave output power in nearly diffraction limited beam when mounted epi-down. The same device mounted epi-up demonstrated output power of about 180 mW. Lasers operating in the wavelength range above 3.2 μm with variable deep etched ridge width and two-step ridge design were fabricated and characterized. Two-step ridge waveguide design yielded the lowest threshold current and the highest slope efficiency. Tens of mW of continuous wave output power was obtained in nearly diffraction limited beams in the wavelength range from 3.2 to 3.3 μm near and above 20 °C in both epi-up and epi-down mounting configurations. Laterally-coupled 2-nd-order distributed feedback lasers operated near 3.22 μm in continuous wave regime at room temperatures with more than 10 mW of output power at room temperature in epi-up mounted configuration.

  1. Simultaneous sensing of temperature, CO, and CO2 in a scramjet combustor using quantum cascade laser absorption spectroscopy

    Science.gov (United States)

    Spearrin, R. M.; Goldenstein, C. S.; Schultz, I. A.; Jeffries, J. B.; Hanson, R. K.

    2014-07-01

    A mid-infrared laser absorption sensor was developed for gas temperature and carbon oxide (CO, CO2) concentrations in high-enthalpy, hydrocarbon combustion flows. This diagnostic enables non-intrusive, in situ measurements in harsh environments produced by hypersonic propulsion ground test facilities. The sensing system utilizes tunable quantum cascade lasers capable of probing the fundamental mid-infrared absorption bands of CO and CO2 in the 4-5 µm wavelength domain. A scanned-wavelength direct absorption technique was employed with two lasers, one dedicated to each species, free-space fiber-coupled using a bifurcated hollow-core fiber for remote light delivery on a single line of sight. Scanned-wavelength modulation spectroscopy with second-harmonic detection was utilized to extend the dynamic range of the CO measurement. The diagnostic was field-tested on a direct-connect scramjet combustor for ethylene-air combustion. Simultaneous, laser-based measurements of carbon monoxide and carbon dioxide provide a basis for evaluating combustion completion or efficiency with temporal and spatial resolution in practical hydrocarbon-fueled engines.

  2. Laser applications in thin-film photovoltaics

    Science.gov (United States)

    Bartlome, R.; Strahm, B.; Sinquin, Y.; Feltrin, A.; Ballif, C.

    2010-08-01

    We review laser applications in thin-film photovoltaics (thin-film Si, CdTe, and Cu(In,Ga)Se2 solar cells). Lasers are applied in this growing field to manufacture modules, to monitor Si deposition processes, and to characterize opto-electrical properties of thin films. Unlike traditional panels based on crystalline silicon wafers, the individual cells of a thin-film photovoltaic module can be serially interconnected by laser scribing during fabrication. Laser scribing applications are described in detail, while other laser-based fabrication processes, such as laser-induced crystallization and pulsed laser deposition, are briefly reviewed. Lasers are also integrated into various diagnostic tools to analyze the composition of chemical vapors during deposition of Si thin films. Silane (SiH4), silane radicals (SiH3, SiH2, SiH, Si), and Si nanoparticles have all been monitored inside chemical vapor deposition systems. Finally, we review various thin-film characterization methods, in which lasers are implemented.

  3. Laser Application In Photobiology And Photomedicine

    Science.gov (United States)

    Anders, Angelika

    1981-05-01

    Applications of lasers in photobiology and photomedicine will be reviewed; for example, genetic processes, photosynthesis, vision, spectroscopy of skin, phototherapy and photochemotherapy of dermatosis and tumors are considered. New results and future possibilities are discussed.

  4. Application of Laser Irradiation for Restorative Treatments

    Science.gov (United States)

    Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

    2016-01-01

    Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal hemorrhage, sterilization, healing of collagenic proteins, formation of a fibrous matrix, and inducing hard tissue barrier. Nevertheless, there are many controversies in literatures regarding their effects on the quality of bonded restorations. It hampered a wide application of lasers in some aspects of restorative dentistry and requirements to identify the best way to use this technology. The aim of this mini review is to explain special characteristics of laser therapy and to introduce the possible applications of laser devices for dental purposes. PMID:27990188

  5. Application of Laser Irradiation for Restorative Treatments.

    Science.gov (United States)

    Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

    2016-01-01

    Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal hemorrhage, sterilization, healing of collagenic proteins, formation of a fibrous matrix, and inducing hard tissue barrier. Nevertheless, there are many controversies in literatures regarding their effects on the quality of bonded restorations. It hampered a wide application of lasers in some aspects of restorative dentistry and requirements to identify the best way to use this technology. The aim of this mini review is to explain special characteristics of laser therapy and to introduce the possible applications of laser devices for dental purposes.

  6. Laser power beaming for satellite applications

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, H.W.

    1993-09-22

    A serious consideration of laser power beaming for satellite applications appears to have grown out of a NASA mission analysis for transmitting power to lunar bases during the two week dark period. System analyses showed that laser power beaming to the moon in conjunction with efficient, large area solar cell collection panels, were an attractive alternative to other schemes such as battery storage and nuclear generators, largely because of the high space transportation costs. The primary difficulty with this scheme is the need for very high average power visible lasers. One system study indicated that lasers in excess of 10 MW at a wavelength of approximately 850 nm were required. Although such lasers systems have received much attention for military applications, their realization is still a long term goal.

  7. High-accuracy and high-sensitivity spectroscopic measurement of dinitrogen pentoxide (N2O5) in an atmospheric simulation chamber using a quantum cascade laser.

    Science.gov (United States)

    Yi, Hongming; Wu, Tao; Lauraguais, Amélie; Semenov, Vladimir; Coeur, Cecile; Cassez, Andy; Fertein, Eric; Gao, Xiaoming; Chen, Weidong

    2017-09-15

    A spectroscopic instrument based on a mid-infrared external cavity quantum cascade laser (EC-QCL) was developed for high-accuracy measurements of dinitrogen pentoxide (N2O5) at the ppbv-level. A specific concentration retrieval algorithm was developed to remove, from the broadband absorption spectrum of N2O5, both etalon fringes resulting from the EC-QCL intrinsic structure and spectral interference lines of H2O vapour absorption, which led to a significant improvement in measurement accuracy and detection sensitivity (by a factor of 10), compared to using a traditional algorithm for gas concentration retrieval. The developed EC-QCL-based N2O5 sensing platform was evaluated by real-time tracking N2O5 concentration in its most important nocturnal tropospheric chemical reaction of NO3 + NO2 ↔ N2O5 in an atmospheric simulation chamber. Based on an optical absorption path-length of Leff = 70 m, a minimum detection limit of 15 ppbv was achieved with a 25 s integration time and it was down to 3 ppbv in 400 s. The equilibrium rate constant Keq involved in the above chemical reaction was determined with direct concentration measurements using the developed EC-QCL sensing platform, which was in good agreement with the theoretical value deduced from a referenced empirical formula under well controlled experimental conditions. The present work demonstrates the potential and the unique advantage of the use of a modern external cavity quantum cascade laser for applications in direct quantitative measurement of broadband absorption of key molecular species involved in chemical kinetic and climate-change related tropospheric chemistry.

  8. Design of a high-performance cascaded boost converter with SiC power devices for photovoltaic applications

    Science.gov (United States)

    Alharbi, Saleh S.; Al-bayati, Ali M. S.; Alharbi, Salah S.; Matin, Mohammad

    2017-08-01

    This paper presents a positive output cascaded boost converter design based on wide bandgap power devices for photovoltaic (PV) applications. The objective is to enhance the converter's performance and efficiency. The converter with SiC MOSFET devices is discussed and compared to a conventional cascaded boost converter based on Silicon (Si) devices. A 205 W cascaded boost converter with an input voltage of 26.6 V and an output voltage of 400 V is simulated to examine the switching behavior and energy loss of each power device. Converter performance with these two power devices is analyzed in terms of total power loss and efficiency at high switching frequencies and loading conditions. SiC power devices in the cascaded converter set-up perform better with minimized switching loss under a wide range of switching frequency conditions. The results show that the cascaded converter with SiC devices significantly reduces total power loss and improves the overall efficiency.

  9. Laser communications for UAV applications

    Science.gov (United States)

    Bloom, Scott H.; Chan, Victor J.; Arnold, Robert L.; Kremer, Richard M.; Liu, C. S.

    1995-09-01

    Laser communications between high flying aircraft such as high altitude unmanned aerial vehicles offers the potential to transfer extremely high amounts of information faster and with a much smaller package than is possible using current radio frequency and microwave technologies. This can be especially important in transferring time sensitive reconnaissance information because the value of the data can deteriorate rapidly with time. BMDO has funded a number of technology efforts through the U.S. Army Space and Strategic Defense Command reducing the risks associated with laser communications. One of these efforts, at ThermoTrex Corporation in San Diego, California, is now being carried forward towards an advanced technology demonstration. The program leads to the demonstration of high data rate communications of 270 MBPS (mega bits per second) to 1.2 GBPS (giga bits per second) between high altitude aircraft and between a satellite and the ground. The laser communications terminals incorporate atomic line filter technology for background light rejection during acquisition, reactionless Roto-Lok offset cable drive gimbals for fast slewing and high accuracy pointing, and direct digital modulation of semiconductor diode lasers detected with low noise avalanche photodiodes. We present results of a 42 km, 1.2 GBPS laser communications demonstration performed at NASA/JPL Table Mountain facility in Wrightwood, Calif., a 10 km, 1.2 GBPS laser communications demonstration at NRAD in San Diego, Calif., and preliminary results of a 150 km, 1.2 GBPS laser communications demonstration between the islands of Maui and Hawaii.

  10. Applications of the Excimer Laser: A Review.

    Science.gov (United States)

    Beggs, Sarah; Short, Jack; Rengifo-Pardo, Monica; Ehrlich, Alison

    2015-11-01

    The 308-nm excimer laser has been approved by the Food and Drug Administration for the treatment of psoriasis and vitiligo. Its ability to treat localized areas has led to many studies determining its potential in the treatment of focal diseases with inflammation or hypopigmentation. To review the different applications of the 308-nm excimer laser for treating dermatologic conditions. An extensive literature review was conducted by searching PubMed, MEDLINE, and ClinicalKey to find articles pertaining to dermatologic conditions treated with the 308-nm excimer laser. Articles published that contributed to new applications of the excimer laser were included, as well as initial studies utilizing the excimer laser. The outcomes and results were compiled for different dermatologic conditions treated with the excimer laser. The 308-nm excimer laser has a wide range of uses for focal inflammatory and hypopigmented conditions. Treatment is generally well tolerated, with few adverse reactions. Larger studies and studies evaluating the long-term effects of the 308-nm excimer laser are needed.

  11. [The study of the human complement cascade of proteolysis as a target of laser irradiation].

    Science.gov (United States)

    Galebskaia, L V; Andreeva, L A; Solovtsova, I L; Solov'eva, M A; Petrishchev, N N

    2009-01-01

    Samples of human blood plasma were irradiated with the laser beam (lamda=633 nm, P=13 mW, t=20 min) in vitro. In experimental and control (incubated in the dark) samples the complement hemolytic activity was measured. Laser irradiation had minor influence on the duration of lag-period and the rate of complement-dependent hemolysis via classical and alternative pathways; it also did not alter the functional activity of factor B, components C2 and C3. Nevertheless laser irradiation effect was seen in essential reduction of a bystander lysis coefficient. This new fact can elucidate some aspects of the clinical effectiveness of the blood laser irradiation.

  12. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André; Marschall, Sebastian; Jensen, Ole Bjarlin

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, dio...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications.......Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... lasers simultaneously offer tunability, high-power emission and compact size at fairly low cost. Therefore, diode lasers are increasingly preferred in important applications, such as photocoagulation, optical coherence tomography, diffuse optical imaging, fluorescence lifetime imaging, and terahertz...

  13. Propene concentration sensing for combustion gases using quantum-cascade laser absorption near 11 μm

    KAUST Repository

    Chrystie, Robin

    2015-05-29

    We report on a strategy to measure, in situ, the concentration of propene (C3H6) in combustion gases using laser absorption spectroscopy. Pyrolysis of n-butane was conducted in a shock tube, in which the resultant gases were probed using an extended cavity quantum-cascade laser. A differential absorption approach using online and offline wavelengths near λ = 10.9 μm enabled discrimination of propene, cancelling the effects of spectral interference from the simultaneous presence of intermediate hydrocarbon species during combustion. Such interference-free measurements were facilitated by exploiting the =C–H bending mode characteristic to alkenes (olefins). It was confirmed, for intermediate species present during pyrolysis of n-butane, that their absorption cross sections were the same magnitude for both online and offline wavelengths. Hence, this allowed time profiles of propene concentration to be measured during pyrolysis of n-butane in a shock tube. Time profiles of propene subsequent to a passing shock wave exhibit trends similar to that predicted by the well-established JetSurF 1.0 chemical kinetic mechanism, albeit lower by a factor of two. Such a laser diagnostic is a first step to experimentally determining propene in real time with sufficient time resolution, thus aiding the refinement and development of chemical kinetic models for combustion. © 2015 Springer-Verlag Berlin Heidelberg

  14. Laser measurement technology fundamentals and applications

    CERN Document Server

    Donges, Axel

    2015-01-01

    Laser measurement technology has evolved in the last years in a versatile and reflationary way. Today, its methods are indispensable for research and development activities as well as for production technology. Every physicist and engineer should therefore gain a working knowledge of laser measurement technology. This book closes the gap of existing textbooks. It introduces in a comprehensible presentation laser measurement technology in all its aspects. Numerous figures, graphs and tables allow for a fast access into the matter. In the first part of the book the important physical and optical basics are described being necessary to understand laser measurement technology. In the second part technically significant measuring methods are explained and application examples are presented. Target groups of this textbook are students of natural and engineering sciences as well as working physicists and engineers, who are interested to make themselves familiar with laser measurement technology and its fascinating p...

  15. High-power optics lasers and applications

    CERN Document Server

    Apollonov, Victor V

    2015-01-01

    This book covers the basics, realization and materials for high power laser systems and high power radiation interaction with  matter. The physical and technical fundamentals of high intensity laser optics and adaptive optics and the related physical processes in high intensity laser systems are explained. A main question discussed is: What is power optics? In what way is it different from ordinary optics widely used in cameras, motion-picture projectors, i.e., for everyday use? An undesirable consequence of the thermal deformation of optical elements and surfaces was discovered during studies of the interaction with powerful incident laser radiation. The requirements to the fabrication, performance and quality of optical elements employed within systems for most practical applications are also covered. The high-power laser performance is generally governed by the following: (i) the absorption of incident optical radiation (governed primarily by various absorption mechanisms), (ii) followed by a temperature ...

  16. Solid state laser systems for space application

    Science.gov (United States)

    Kay, Richard B.

    1994-01-01

    Since the last report several things have happened to effect the research effort. In laser metrology, measurements using Michelson type interferometers with an FM modulated diode laser source have been performed. The discrete Fourier transform technique has been implemented. Problems associated with this technique as well as the overall FM scheme were identified. The accuracy of the technique is not at the level we would expect at this point. We are now investigating the effect of various types of noise on the accuracy as well as making changes to the system. One problem can be addressed by modifying the original optical layout. Our research effort was also expanded to include the assembly and testing of a diode pumped\\Nd:YAG laser pumped\\Ti sapphire laser for possible use in sounding rocket applications. At this stage, the diode pumped Nd:YAG laser has been assembled and made operational.

  17. Triple-wavelength Nd-laser system by cascaded electro-optic periodically poled lithium niobate Bragg modulator.

    Science.gov (United States)

    Lin, Shou-Tai; Hsieh, Chuan-Sheng

    2012-12-31

    This study presents a diode-pumped cw triple-wavelength Nd:GdVO₄ laser system using an electro-optic periodically poled lithium niobate (PPLN) Bragg modulator. The PPLN consists of two cascaded sections, 20.3 μm and 25.7 μm, functioning as loss modulators for 1063 and 1342 nm at the same Bragg incident angle. When switching the dc voltages on PPLN and applying 25 W pump power, the output wavelength can be selected among 912, 1063, and 1342 nm with output power of 2, 5, and 1.4 W, respectively. The device is capable of triple-wavelength generation simultaneous when applied voltages are 180 (Λ = 20.3 μm) and -50 V (Λ = 25.7 μm) at a 25 W pump power. Gain competition induced power instability was also observed.

  18. Thermal annealing of lattice-matched InGaAs/InAlAs Quantum-Cascade Lasers

    Science.gov (United States)

    Mathonnière, Sylvain; Semtsiv, M. P.; Ted Masselink, W.

    2017-11-01

    We describe the evolution of optical power, threshold current, and emission wavelength of a lattice-matched InGaAs/InAlAs Quantum-Cascade Laser (QCL) emitting at 13 μm grown by gas-source molecular-beam epitaxy under thermal annealing. Pieces from the same 2-in wafer were annealed at 600 °C, 650 °C, or 700 °C for 1 h; one control piece remained unannealed. No change in threshold current and emission wavelength was observed. The slope efficiency and maximum emission power increase for the 600 °C anneal, but higher annealing temperatures resulted in degraded performance. This result stands in contrast with the observation that strain-compensated structures cannot withstand annealing temperature of 600 °C. Useful information for post-growth processing steps and the role of interface roughness in QCL performance are obtained.

  19. A calibration-free ammonia breath sensor using a quantum cascade laser with WMS 2f/1f

    KAUST Repository

    Owen, Kyle

    2013-12-22

    The amount of ammonia in exhaled breath has been linked to a variety of adverse medical conditions, including chronic kidney disease (CKD). The development of accurate, reliable breath sensors has the potential to improve medical care. Wavelength modulation spectroscopy with second harmonic normalized by the first harmonic (WMS 2f/1f) is a sensitive technique used in the development of calibration-free sensors. An ammonia gas sensor is designed and developed that uses a quantum cascade laser operating near 1,103.44 cm -1 and a multi-pass cell with an effective path length of 76.45 m. The sensor has a 7 ppbv detection limit and 5 % total uncertainty for breath measurements. The sensor was successfully used to detect ammonia in exhaled breath and compare healthy patients to patients diagnosed with CKD. © 2013 Springer-Verlag Berlin Heidelberg.

  20. Characterization of iron doped indium phosphide as a current blocking layer in buried heterostructure quantum cascade lasers

    Science.gov (United States)

    Nida, S.; Hinkov, B.; Gini, E.; Faist, J.

    2017-03-01

    This work analyzes transport through metal organic chemical vapour deposition grown Iron doped Indium Phosphide (InP:Fe) for use as a current blocking layer in buried heterostructure Quantum Cascade Lasers. The nature of Iron incorporation in InP and electrical transport properties of InP:Fe is investigated via simulation and compared with measurement. Through simulations, we are able to predict the threshold for the onset of current rise in test structures due to avalanche injection of carriers. In addition, the benefit of InAlAs barriers inserted in InP:Fe layers is investigated and found to reduce the leakage current at lower biases while delaying the onset of avalanche. In buried heterostructure configuration, we have determined that non ideal regrowth profiles make the structure more susceptible to high field effects such as avalanche injection and trap filling that induce leakage currents.

  1. Broadly continuously tunable slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Bo; Zeng, Yong Quan; Liang, Guozhen; Hu, Xiao Nan; Rodriguez, Etienne [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Tao, Jin [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore); Wang, Qi Jie, E-mail: qjwang@ntu.edu.sg [OPTIMUS, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); CDPT, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore 637371 (Singapore)

    2015-09-14

    We report our progress in the development of broadly tunable single-mode slot waveguide quantum cascade lasers based on a continuum-to-continuum active region design. The electroluminescence spectrum of the continuum-to-continuum active region design has a full width at half maximum of 440 cm{sup −1} at center wavelength ∼10 μm at room temperature (300 K). Devices using the optimized slot waveguide structure and the continuum-to-continuum design can be tuned continuously with a lasing emission over 42 cm{sup −1}, from 9.74 to 10.16 μm, at room temperature by using only current tuning scheme, together with a side mode suppression ratio of above 15 dB within the whole tuning range.

  2. Absolute spectroscopy near 7.8 {\\mu} m with a comb-locked extended-cavity quantum-cascade-laser

    KAUST Repository

    Lamperti, Marco

    2017-07-31

    We report the first experimental demonstration of frequency-locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locking scheme is applied to carry out absolute spectroscopy of N2O lines near 7.87 {\\\\mu}m with an accuracy of ~60 kHz. Thanks to a single mode operation over more than 100 cm^{-1}, the comb-locked EC-QCL shows great potential for the accurate retrieval of line center frequencies in a spectral region that is currently outside the reach of broadly tunable cw sources, either based on difference frequency generation or optical parametric oscillation. The approach described here can be straightforwardly extended up to 12 {\\\\mu}m, which is the current wavelength limit for commercial cw EC-QCLs.

  3. High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xuemin; Shen, Changle; Jiang, Tao; Zhan, Zhiqiang; Deng, Qinghua; Li, Weihua; Wu, Weidong, E-mail: wuweidongding@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900, Sichuan (China); Yang, Ning; Chu, Weidong; Duan, Suqing [Institute of Applied Physics and Computational Mathematics, Beijing, 100088 (China)

    2016-07-15

    Terahertz quantum cascade lasers with a record output power up to ∼0.23 W in continuous wave mode were obtained. We show that the optimal 2.9-mm-long device operating at 3.11 THz has a low threshold current density of 270 A/cm{sup 2} at ∼15 K. The maximum operating temperature arrived at ∼65 K in continuous wave mode and the internal quantum efficiencies decreased from 0.53 to 0.19 for the devices with different cavity lengths. By using one convex lens with the effective focal length of 13 mm, the beam profile was collimated to be a quasi Gaussian distribution.

  4. Quartz-enhanced photoacoustic detection of ethylene using a 10.5 μm quantum cascade laser.

    Science.gov (United States)

    Wang, Zhen; Li, Zhili; Ren, Wei

    2016-02-22

    A quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor has been developed for the sensitive detection of ethylene (C2H4) at 10.5 µm using a continuous-wave distributed-feedback quantum cascade laser. At this long-wavelength infrared, the key acoustic elements of quartz tuning fork and micro-resonators were optimized to improve the detection signal-to-noise ratio by a factor of >4. The sensor calibration demonstrated an excellent linear response (R2>0.999) to C2H4 concentration at the selected operating pressure of 500 and 760 Torr. With a minimum detection limit of 50 parts per billion (ppb) achieved at an averaging time of 70 s, the sensor has been deployed for measuring the C2H4 efflux during the respiration of biological samples in an agronomic environment.

  5. Compact, rapid, and rugged detector of military and improvised explosives based on external grating cavity quantum cascade lasers

    Science.gov (United States)

    Tsekoun, Alexei; Dunayevskiy, Ilya; Maulini, Richard; Barron-Jimenez, Rodolfo; Lyakh, Arkadiy; Patel, C. Kumar N.

    2009-08-01

    Early detection of explosive substances is the first and most difficult step in defeating explosive devices. Many currently available methods suffer from fundamental failure modes limiting their realworld suitability. Infrared spectroscopy is ideal for reliable identification of explosives since it probes the chemical composition of molecules. Quantum cascade lasers rapidly became the light source of choice of IR spectroscopy due to their wavelength agility, relatively high output power, and small size and weight. Our compact, rapid, and rugged multi-explosives sensor based on external grating cavity QCLs simultaneously detects TNT, TATP, and acetone while being immune to ammonium nitrate interference. The instrument features low false alarm rate, and low probability of false negatives. Receiver operation characteristics curves are presented.

  6. Ppb-level detection of nitric oxide using an external cavity quantum cascade laser based QEPAS sensor.

    Science.gov (United States)

    Dong, Lei; Spagnolo, Vincenzo; Lewicki, Rafał; Tittel, Frank K

    2011-11-21

    Geometrical parameters of micro-resonator for a quartz enhanced photoacoustic spectroscopy sensor are optimized to perform sensitive and background-free spectroscopic measurements using mid-IR quantum cascade laser (QCL) excitation sources. Such an optimized configuration is applied to nitric oxide (NO) detection at 1900.08 cm(-1) (5.26 µm) with a widely tunable, mode-hop-free external cavity QCL. For a selected NO absorption line that is free from H(2)O and CO(2) interference, a NO detection sensitivity of 4.9 parts per billion by volume is achieved with a 1-s averaging time and 66 mW optical excitation power. This NO detection limit is determined at an optimal gas pressure of 210 Torr and 2.5% of water vapor concentration. Water is added to the analyzed mixture in order to improve the NO vibrational-translational relaxation process. © 2011 Optical Society of America

  7. NONLINEAR SYSTEM MODELING USING SINGLE NEURON CASCADED NEURAL NETWORK FOR REAL-TIME APPLICATIONS

    Directory of Open Access Journals (Sweden)

    S. Himavathi

    2012-04-01

    Full Text Available Neural Networks (NN have proved its efficacy for nonlinear system modeling. NN based controllers and estimators for nonlinear systems provide promising alternatives to the conventional counterpart. However, NN models have to meet the stringent requirements on execution time for its effective use in real time applications. This requires the NN model to be structurally compact and computationally less complex. In this paper a parametric method of analysis is adopted to determine the compact and faster NN model among various neural network architectures. This work proves through analysis and examples that the Single Neuron Cascaded (SNC architecture is distinct in providing compact and simpler models requiring lower execution time. The unique structural growth of SNC architecture enables automation in design. The SNC Network is shown to combine the advantages of both single and multilayer neural network architectures. Extensive analysis on selected architectures and their models for four benchmark nonlinear theoretical plants and a practical application are tested. A performance comparison of the NN models is presented to demonstrate the superiority of the single neuron cascaded architecture for online real time applications.

  8. Molecular Laser Spectroscopy as a Tool for Gas Analysis Applications

    Directory of Open Access Journals (Sweden)

    Javis Anyangwe Nwaboh

    2011-01-01

    Full Text Available We have used the traceable infrared laser spectrometric amount fraction measurement (TILSAM method to perform absolute concentration measurements of molecular species using three laser spectroscopic techniques. We report results performed by tunable diode laser absorption spectroscopy (TDLAS, quantum cascade laser absorption spectroscopy (QCLAS, and cavity ring down spectroscopy (CRDS, all based on the TILSAM methodology. The measured results of the different spectroscopic techniques are in agreement with respective gravimetric values, showing that the TILSAM method is feasible with all different techniques. We emphasize the data quality objectives given by traceability issues and uncertainty analyses.

  9. High-Efficiency and High-Power Mid-Wave Infrared Cascade Lasers

    Science.gov (United States)

    2012-10-01

    Ω is the Rabi frequency associated with the optical field and is defined as (in the unit of energy) Ω...offset δU in Eq. (3.1). For QC lasers with design wavelength >8μm, lattice - matched In0.53Ga0.47As/Al0.48In0.52As on InP is used; for QC lasers with

  10. Observation of double resonant laser induced transitions in the $v = n - l - 1 = 2$ metastable cascade of antiprotonic helium-4 atoms

    CERN Document Server

    Hayano, R S; Tamura, H; Torii, H A; Hori, Masaki; Maas, F E; Morita, N; Kumakura, M; Sugai, I; Hartmann, F J; Daniel, H; Von Egidy, T; Ketzer, B; Pohl, R; Horváth, D; Eades, John; Widmann, E; Yamazaki, T

    1997-01-01

    A new laser-induced resonant transition in the $v=n-l-1=2$ metastable cascade of antiprotonic $^4$He atoms has been found by using a double resonance technique. This was done by setting the first laser to the already known 470.724 nm resonance ($(n,l)=(37,34)\\rightarrow (36,33)$), while the $(38,35)\\rightarrow (37,34)$ transition was searched for with the second laser. The resonant transition was found at wavelength of 529.622$\\pm$0.003 nm, showing excellent agreement with a recent prediction of Korobov.

  11. Ophthalmic applications of femtosecond lasers

    Science.gov (United States)

    Kurtz, Ron M.; Spooner, Greg J. R.; Sletten, Karin R.; Yen, Kimberly G.; Sayegh, Samir I.; Loesel, Frieder H.; Horvath, Christopher; Liu, HsiaoHua; Elner, Victor; Cabrera, Delia; Muenier, Marie-Helene; Sacks, Zachary S.; Juhasz, Tibor; Miller, Doug L.; Williams, A. R.

    1999-06-01

    We investigated three potential femtosecond laser ophthalmic procedures: intrastromal refractive surgery, transcleral photodisruptive glaucoma surgery and photodisruptive ultrasonic lens surgery. A highly reliable, all-solid-state system was used to investigate tissue effects and demonstrate clinical practicality. Compared with longer duration pulses, femtosecond laser-tissue interactions are characterized by smaller and more deterministic photodisruptive energy thresholds, smaller shock wave and cavitation bubble sizes. Scanning a 5 (mu) spot below the target tissue surface produced contiguous tissue effects. Various scanning patterns were used to evaluate the efficacy, safety, and stability of three intrastromal refractive procedures in animal eyes: corneal flap cutting, keratomileusis, and intrastromal vision correction (IVC). Superior dissection and surface quality results were obtained for the lamellar procedures. IVC in rabbits revealed consistent, stable pachymetric changes, without significant inflammation or corneal transparency degradation. Transcleral photodisruption was evaluated as a noninvasive method for creating partial thickness scleral channels to reduce elevated intraocular pressure associated with glaucoma. Photodisruption at the internal scleral surface was demonstrated by focusing through tissue in vitro without collateral damage. Femtosecond photodisruptions nucleated ultrasonically driven cavitation to demonstrate non-invasive destruction of in vitro lens tissue. We conclude that femtosecond lasers may enable practical novel ophthalmic procedures, offering advantages over current techniques.

  12. High energy laser demonstrators for defense applications

    Science.gov (United States)

    Jung, M.; Riesbeck, Th.; Schmitz, J.; Baumgärtel, Th.; Ludewigt, K.; Graf, A.

    2017-01-01

    Rheinmetall Waffe Munition has worked since 30 years in the area of High Energy Laser (HEL) for defence applications, starting from pulsed CO2 to pulsed glass rods lasers. In the last decade Rheinmetall Waffe Munition changed to diode pumped solid state laser (DPSSL) technology and has successfully developed, realised and tested a variety of versatile HEL weapon demonstrators for air- and ground defence scenarios like countering rocket, artillery, mortar, missile (RAMM), unmanned aerial systems (UAS) and unexploded ordnances clearing. By employing beam superimposing technology and a modular laser weapon concept, the total optical power has been successively increased. Stationary weapon platforms, military vehicles and naval platforms have been equipped with high energy laser effectors. The contribution gives a summary of the most recent development stages of Rheinmetalls HEL weapon program. In addition to the stationary 30 kW laser weapon demonstrator, we present vehicle based HEL demonstrators: the 5 kW class Mobile HEL Effector Track V, the 20 kW class Mobile HEL Effector Wheel XX and the 50 kW class Mobile HEL Effector Container L and the latest 10 kW HEL effector integrated in the naval weapon platform MLG 27. We describe the capabilities of these demonstrators against different potential targets. Furthermore, we will show the capability of the 30 kW stationary Laser Weapon Demonstrator integrated into an existing ground based air defence system to defeat saturated attacks of RAMM and UAS targets.

  13. High Power Diode Lasers Technology and Applications

    CERN Document Server

    Bachmann, Friedrich; Poprawe, Reinhart

    2007-01-01

    In a very comprehensive way this book covers all aspects of high power diode laser technology for materials processing. Basics as well as new application oriented results obtained in a government funded national German research project are described in detail. Along the technological chain after a short introduction in the second chapter diode laser bar technology is discussed regarding structure, manufacturing technology and metrology. The third chapter illuminates all aspects of mounting and cooling, whereas chapter four gives wide spanning details on beam forming, beam guiding and beam combination, which are essential topics for incoherently coupled multi-emitter based high power diode lasers. Metrology, standards and safety aspects are the theme of chapter five. As an outcome of all the knowledge from chapter two to four various system configurations of high power diode lasers are described in chapter six; not only systems focussed on best available beam quality but especially also so called "modular" set...

  14. Laser anemometer measurements and computations for transonic flow conditions in an annular cascade of high turning core turbine vanes

    Science.gov (United States)

    Goldman, Louis J.

    1993-01-01

    An advanced laser anemometer (LA) was used to measure the axial and tangential velocity components in an annular cascade of turbine stator vanes operating at transonic flow conditions. The vanes tested were based on a previous redesign of the first-stage stator in a two-stage turbine for a high-bypass-ratio engine. The vanes produced 75 deg of flow turning. Tests were conducted on a 0.771-scale model of the engine-sized stator. The advanced LA fringe system employed an extremely small 50-micron diameter probe volume. Window correction optics were used to ensure that the laser beams did not uncross in passing through the curved optical access port. Experimental LA measurements of velocity and turbulence were obtained at the mean radius upstream of, within, and downstream of the stator vane row at an exit critical velocity ratio of 1.050 at the hub. Static pressures were also measured on the vane surface. The measurements are compared, where possible, with calculations from a three-dimensional inviscid flow analysis. Comparisons were also made with the results obtained previously when these same vanes were tested at the design exit critical velocity ratio of 0.896 at the hub. The data are presented in both graphical and tabulated form so that they can be readily compared against other turbomachinery computations.

  15. Quantum cascade laser absorption spectroscopy with the amplitude-to-time conversion technique for atmospheric-pressure plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Yumii, Takayoshi; Kimura, Noriaki [Mitsui Engineering and Shipbuilding Co., Ltd., Tamahara 3-16-1, Tamano, Okayama 706-0014 (Japan); Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871 (Japan); Hamaguchi, Satoshi [Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871 (Japan)

    2013-06-07

    The NO{sub 2} concentration, i.e., density, in a small plasma of a nitrogen oxide (NOx) treatment reactor has been measured by highly sensitive laser absorption spectroscopy. The absorption spectroscopy uses a single path of a quantum cascade laser beam passing through a plasma whose dimension is about 1 cm. The high sensitivity of spectroscopy is achieved by the amplitude-to-time conversion technique. Although the plasma reactor is designed to convert NO in the input gas to NO{sub 2}, it has been demonstrated by this highly sensitive absorption spectroscopy that NO{sub 2} in a simulated exhaust gas that enters the reactor is decomposed by the plasma first and then NO{sub 2} is formed again, possibly more than it was decomposed, through a series of gas-phase reactions by the time the gas exits the reactor. The observation is consistent with that of an earlier study on NO decomposition by the same type of a plasma reactor [T. Yumii et al., J. Phys. D 46, 135202 (2013)], in which a high concentration of NO{sub 2} was observed at the exit of the reactor.

  16. Probing organometallic reactions by time-resolved infrared spectroscopy in solution and in the solid state using quantum cascade lasers.

    Science.gov (United States)

    Calladine, James A; Horvath, Raphael; Davies, Andrew J; Wriglesworth, Alisdair; Sun, Xue-Zhong; George, Michael W

    2015-05-01

    The photochemistry and photophysics of metal carbonyl compounds (W(CO)6, Cp*Rh(CO)2 (Cp* = η(5)-C5Me5), and fac-[Re(CO)3(4,4'-bpy)2Br] [bpy = bipyridine]) have been examined on the nanosecond timescale using a time-resolved infrared spectrometer with an external cavity quantum cascade laser (QCL) as the infrared source. We show the photochemistry of W(CO)6 in alkane solution is easily monitored, and very sensitive measurements are possible with this approach, meaning it can monitor small transients with absorbance changes less than 10(-6) ΔOD. The C-H activation of Cp*Rh(CO)(C6H12) to form Cp*Rh(CO)(C6H11)H occurs within the first few tens of nanoseconds following photolysis, and we demonstrate that kinetics obtained following deconvolution are in excellent agreement with those measured using an ultrafast laser-based spectrometer. We also show that the high flux and tunability of QCLs makes them suited for solid-state and time-resolved measurements.

  17. Real time ammonia detection in exhaled human breath using a distributed feedback quantum cascade laser based sensor

    Science.gov (United States)

    Lewicki, Rafał; Kosterev, Anatoliy A.; Thomazy, David M.; Risby, Terence H.; Solga, Steven; Schwartz, Timothy B.; Tittel, Frank K.

    2011-01-01

    A continuous wave, thermoelectrically cooled, distributed feedback quantum cascade laser (DFB-QCL) based sensor platform for the quantitative detection of ammonia (NH3) concentrations present in exhaled human breath is reported. The NH3 concentration measurements are performed with a 2f wavelength modulation quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is very well suited for real time breath analysis, due to the fast gas exchange inside a compact QEPAS gas cell. An air-cooled DFB-QCL was designed to target the interference-free NH3 absorption line located at 967.35 cm-1 (λ~10.34 μm). The laser is operated at 17.5 °C, emitting ~ 24 mW of optical power at the selected wavelength. A 1σ minimum detectable concentration of ammonia for the line-locked NH3 sensor is ~ 6 ppb with 1 sec time resolution. The NH3 sensor, packaged in a 12"x14"x10" housing, is currently installed at a medical breath research center in Bethlehem, PA and tested as an instrument for non-invasive verification of liver and kidney disorders based on human breath samples.

  18. High-quality electron beam generation and bright betatron radiation from a cascaded laser wakefield accelerator (Conference Presentation)

    Science.gov (United States)

    Liu, Jiansheng; Wang, Wentao; Li, Wentao; Qi, Rong; Zhang, Zhijun; Yu, Changhai; Wang, Cheng; Liu, Jiaqi; Qing, Zhiyong; Ming, Fang; Xu, Yi; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2017-05-01

    One of the major goals of developing laser wakefiled accelerators (LWFAs) is to produce compact high-energy electron beam (e-beam) sources, which are expected to be applied in developing compact x-ray free-electron lasers and monoenergetic gamma-ray sources. Although LWFAs have been demonstrated to generate multi-GeV e-beams, to date they are still failed to produce high quality e beams with several essential properties (narrow energy spread, small transverse emittance and high beam charge) achieved simultaneously. Here we report on the demonstration of a high-quality cascaded LWFA experimentally via manipulating electron injection, seeding in different periods of the wakefield, as well as controlling energy chirp for the compression of energy spread. The cascaded LWFA was powered by a 1-Hz 200-TW femtosecond laser facility at SIOM. High-brightness e beams with peak energies in the range of 200-600 MeV, 0.4-1.2% rms energy spread, 10-80 pC charge, and 0.2 mrad rms divergence are experimentally obtained. Unprecedentedly high 6-dimensional (6-D) brightness B6D,n in units of A/m2/0.1% was estimated at the level of 1015-16, which is very close to the typical brightness of e beams from state-of-the-art linac drivers and several-fold higher than those of previously reported LWFAs. Furthermore, we propose a scheme to minimize the energy spread of an e beam in a cascaded LWFA to the one-thousandth-level by inserting a stage to compress its longitudinal spatial distribution via velocity bunching. In this scheme, three-segment plasma stages are designed for electron injection, e-beam length compression, and e-beam acceleration, respectively. A one-dimensional theory and two-dimensional particle-in-cell simulations have demonstrated this scheme and an e beam with 0.2% rms energy spread and low transverse emittance could be generated without loss of charge. Based on the high-quality e beams generated in the LWFA, we have experimentally realized a new scheme to enhance the

  19. Innovations in high power fiber laser applications

    Science.gov (United States)

    Beyer, Eckhard; Mahrle, Achim; Lütke, Matthias; Standfuss, Jens; Brückner, Frank

    2012-02-01

    Diffraction-limited high power lasers represent a new generation of lasers for materials processing, characteristic traits of which are: smaller, cost-effective and processing "on the fly". Of utmost importance is the high beam quality of fiber lasers which enables us to reduce the size of the focusing head incl. scanning mirrors. The excellent beam quality of the fiber laser offers a lot of new applications. In the field of remote cutting and welding the beam quality is the key parameter. By reducing the size of the focusing head including the scanning mirrors we can reach scanning frequencies up to 1.5 kHz and in special configurations up to 4 kHz. By using these frequencies very thin and deep welding seams can be generated experienced so far with electron beam welding only. The excellent beam quality of the fiber laser offers a high potential for developing new applications from deep penetration welding to high speed cutting. Highly dynamic cutting systems with maximum speeds up to 300 m/min and accelerations up to 4 g reduce the cutting time for cutting complex 2D parts. However, due to the inertia of such systems the effective cutting speed is reduced in real applications. This is especially true if complex shapes or contours are cut. With the introduction of scanner-based remote cutting systems in the kilowatt range, the effective cutting speed on the contour can be dramatically increased. The presentation explains remote cutting of metal foils and sheets using high brightness single mode fiber lasers. The presentation will also show the effect of optical feedback during cutting and welding with the fiber laser, how those feedbacks could be reduced and how they have to be used to optimize the cutting or welding process.

  20. Applications for Energy Recovering Free Electron Lasers

    Energy Technology Data Exchange (ETDEWEB)

    George Neil

    2007-08-01

    The availability of high-power, high-brilliance sources of tunable photons from energy-recovered Free Electron Lasers is opening up whole new fields of application of accelerators in industry. This talk will review some of the ideas that are already being put into production, and some of the newer ideas that are still under development.

  1. New Medical Applications Of Metal Vapor Lasers

    Science.gov (United States)

    Anderson, Robert S.; McIntosh, Alexander I.

    1989-06-01

    The first medical application for metal vapor lasers has been granted marketing approval by the FDA. This represents a major milestone for this technology. Metalaser Technologies recently received this approval for its Vasculase unit in the treatment of vascular lesions such as port wine stains, facial telangiectasia and strawberry hemangiomas.

  2. Laser applications in nuclear power plants

    Indian Academy of Sciences (India)

    2014-01-09

    Jan 9, 2014 ... This paper reports the state of the art of using a solid-state Nd:YAG laser for material processing applications such as cutting, welding and drilling of several components of operational nuclear reactors in radioactive environment. We have demonstrated several advantages of laserbased material processing ...

  3. Coagulation and ablation of biological soft tissue by quantum cascade laser with peak wavelength of 5.7 μm

    Directory of Open Access Journals (Sweden)

    Keisuke Hashimura

    2014-05-01

    Full Text Available Molecules such as water, proteins and lipids that are contained in biological tissue absorb mid-infrared (MIR light, which allows such light to be used in laser surgical treatment. Esters, amides and water exhibit strong absorption bands in the 5–7 μm wavelength range, but at present there are no lasers in clinical use that can emit in this range. Therefore, the present study focused on the quantum cascade laser (QCL, which is a new type of semiconductor laser that can emit at MIR wavelengths and has recently achieved high output power. A high-power QCL with a peak wavelength of 5.7 μm was evaluated for use as a laser scalpel for ablating biological soft tissue. The interaction of the laser beam with chicken breast tissue was compared to a conventional CO2 laser, based on surface and cross-sectional images. The QCL was found to have sufficient power to ablate soft tissue, and its coagulation, carbonization and ablation effects were similar to those for the CO2 laser. The QCL also induced comparable photothermal effects because it acted as a pseudo-continuous wave laser due to its low peak power. A QCL can therefore be used as an effective laser scalpel, and also offers the possibility of less invasive treatment by targeting specific absorption bands in the MIR region.

  4. Urological applications of the holmium laser

    Science.gov (United States)

    Beaghler, Marc A.; Poon, Michael W.; Ruckle, Herbert C.; Stewart, Steven C.; Weil, Dane

    1998-07-01

    While the role of endoscopy was initially diagnostic, the advent of improved endoscopes and working instruments have increased its therapeutic applications. One of the most recent advances is the holmium laser. It has a broad range of urological applications due to its ability to fragment all urinary calculi and its soft tissue effects. This laser is based on laser energy delivered in a pulsatile fashion at 2100 nm. The purpose of this study is to report our experience with the holmium laser. A retrospective study of patients undergoing endourological procedures with the holmium laser was performed. One hundred and forty patients underwent 157 procedures. The holmium laser was used for the treatment of urinary calculi in 122 patients. Stone location included 61 renal, 64 ureteral, and 17 bladder stones. Renal stone burden was 17 mm (range 3-50), ureteral stone size averaged 10 mm (range 3 - 35), and mean bladder stone size was 31 mm (range 10 - 60). Other uses included treatment of transitional cell carcinoma of the renal pelvis, ureter, and bladder, incision of ureteral strictures, ureterocele, and prostate, and ablation of renal hemangiomas. Intraoperative and post operative complications were noted. Follow-up for calculi consisted of a plain film of the abdomen at one week and an ultrasound or intravenous pyelogram at six to eight weeks post procedure. No ureteral perforations or strictures occurred. The Holmium laser was capable of fragmenting all urinary calculi in this study. No complications were directly attributable to the Holmium laser. In our initial experience, the Holmium laser is safe and effective in the treatment of urinary pathology. It is the most effective lithotrite available and is able to incise and coagulate soft tissue as well. This combination allows the urologist to treat a variety of urinary pathology using a single modality. Its main limitation is the ability to access lower pole lesions in the upper urinary tract due to the fiber

  5. Energy spread minimization in a cascaded laser wakefield accelerator via velocity bunching (Conference Presentation)

    Science.gov (United States)

    Zhang, Zhijun

    2017-05-01

    We report the observation of energy-spread compensation of electron bunches in a laser wakefield accelerator in experiment. The compensation was caused by the gradient wakefield in plasma wake, and the energy spectra of the bunches evolved during the acceleration so that we propose a new method to diagnose the longitudinal length of the ultrashort electron bunch. By analyzing the energy spectra of electron bunches with different acceleration length, the wakefield gradient difference and the wakefield slope of the bunch could be estimated by combining with the slippage between the plasma wave and the electron bunch, thus the electron bunches' longitudinal length could be estimated. By applying this new method, the longitudinal length of electron bunches with charge of about 40 pC generated from a laser wakefield accelerator was estimated to be (2.4 ± 2.2) μm in experiment, which was in good agreement with three-dimension particle-in-cell simulations.

  6. A Variational Principle for Spontaneous Wiggler Radiation with Applications to Harmonic-Cascade Radiation

    CERN Document Server

    Charman, A E

    2005-01-01

    Within the framework of a Hilbert space formalism, we derive a maximum-power variational principle (MPVP) applicable to classical spontaneous radiation from prescribed current sources. The principe appears similar to, but actually is distinct from, other well-known variational principles associated with Hamilton's principle of stationary action or Rumsey's methods involving "reaction." The techniques have been developed for and applied to the case of undulator radiation from relativistic electron beams, specifically to X-ray generation using an harmonic cascade. Such processes are currently evaluated using extensive calculations or simulation codes which can be slow to evaluate and difficult to set up. The variational principle emerged as a natural step in a simple analytic algorithm to predict the output of a harmonic generation beamline in the low-gain regime based on trial functions for the output radiation. Full three-dimensional effects are included, and it may be generalized to include further effects s...

  7. Ultrafast laser pulses for medical applications

    Science.gov (United States)

    Lubatschowski, Holger; Heisterkamp, Alexander; Will, Fabian; Serbin, Jesper; Bauer, Thorsten; Fallnich, Carsten; Welling, Herbert; Mueller, Wiebke; Schwab, Burkard; Singh, Ajoy I.; Ertmer, Wolfgang

    2002-04-01

    Ultrafast lasers have become a promising tool for micromachining and extremely precise ablation of all kinds of materials. Due to the low energy threshold, thermal and mechanical side effects are limited to the bu micrometers range. The neglection of side effects enables the use of ultrashort laser pulses in a broad field of medical applications. Moreover, the interaction process based on nonlinear absorption offers the opportunity to process transparent tissue three dimensionally inside the bulk. We demonstrate the feasibility of surgical procedures in different fields of medical interest: in ophthalmology intrastromal cutting and preparing of cornael flaps for refractive surgery in living animals is presented. Besides, the very low mechanical side effects enables the use of fs- laser in otoralyngology to treat ocecular bones. Moreover, the precise cutting quality can be used in fields of cardiovascular surgery for the treatment of arteriosklerosis as well as in dentistry to remove caries from dental hard tissue.

  8. Reagent-free monitoring of multiple clinically relevant parameters in human blood plasma using a mid-infrared quantum cascade laser based sensor system.

    Science.gov (United States)

    Brandstetter, Markus; Sumalowitsch, Tamara; Genner, Andreas; Posch, Andreas E; Herwig, Christoph; Drolz, Andreas; Fuhrmann, Valentin; Perkmann, Thomas; Lendl, Bernhard

    2013-07-21

    We present a semi-automated point-of-care (POC) sensor approach for the simultaneous and reagent-free determination of clinically relevant parameters in blood plasma. The portable sensor system performed direct mid-infrared (MIR) transmission measurements of blood plasma samples using a broadly tunable external-cavity quantum cascade laser source with high spectral power density. This enabled the use of a flow cell with a long path length (165 μm) which resulted in high signal-to-noise ratios and a rugged system, insensitive to clogging. Multivariate calibration models were built using well established Partial-Least-Squares (PLS) regression analysis. Selection of spectral pre-processing procedures was optimized by an automated evaluation algorithm. Several analytes, including glucose, lactate, triglycerides, cholesterol, total protein as well as albumin, were successfully quantified in routinely taken blood plasma samples from 67 critically ill patients. Although relying on a spectral range from 1030 cm(-1) to 1230 cm(-1), which is optimal for glucose and lactate but rather unusual for protein analysis, it was possible to selectively determine the albumin and total protein concentrations with sufficient accuracy for POC application.

  9. Mechanism and clinical application of laser acupuncture

    Science.gov (United States)

    Tian, Zhaobing

    1994-08-01

    Low energy laser irradiation in clinical practice can be divided into two categories: irradiation of located parts of the body and laser acupuncture therapy. If the laser with fixed wavelength and proper power is input into certain particular points of the body, it may produce good systemic physiologic effects. This has been proved by many tests on animals and in clinical practice. Some clinical applications are discussed as representative of the therapy. According to the TCM theory on `Ching-lo' (channels), we used the 2 mW - 5 mW laser to treat experimentally more than 30 patients for leuckocytopenia, decreasing of platelets and a lot of inflammatory masses. The effects are dramatic. About the mechanism, we realize that first, the human body is irradiated by the laser, the photon is absorbed by cells, and the cells are polarized and activated. In the next step, the activated energy is transported along the resonance dipoles of the human body. Various physiological functions of the organism and the clinical effects are shown as the final results.

  10. Orthogonal polarization in lasers physical phenomena and engineering applications

    CERN Document Server

    Zhang, Shulian

    2013-01-01

    This practical book summarizes the latest research results of orthogonally polarized lasers, birefringence laser cavities, and their applications. Coverage ranges from basic principles and technologies to the characteristics of different cavities and lasers to various measurement techniques. A number of figures, experimental designs, and measurement curves are included, helping readers gain a thorough understanding of the many applications in modern engineering and start their own projects. Many types of relevant lasers (Helium/Neon lasers, Nd:YAG lasers, laser diodes, etc.) are also discussed

  11. Wide single-mode tuning in quantum cascade lasers with asymmetric Mach-Zehnder interferometer type cavities with separately biased arms

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Mei C., E-mail: meizheng@princeton.edu; Gmachl, Claire F. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Liu, Peter Q. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Institute of Quantum Electronics, ETH Zürich, 8093 Zürich (Switzerland); Wang, Xiaojun; Fan, Jen-Yu; Troccoli, Mariano [AdTech Optics, Inc., City of Industry, California 91748 (United States)

    2013-11-18

    We report on the experimental demonstration of a widely tunable single mode quantum cascade laser with Asymmetric Mach-Zehnder (AMZ) interferometer type cavities with separately biased arms. Current and, consequently, temperature tuning of the two arms of the AMZ type cavity resulted in a single mode tuning range of 20 cm{sup −1} at 80 K in continuous-wave mode operation, a ten-fold improvement from the lasers under a single bias current. In addition, we also observed a five fold increase in the tuning rate as compared to the AMZ cavities controlled by one bias current.

  12. A Quantum Cascade Laser-Based Optical Sensor for Continuous Monitoring of Environmental Methane in Dunkirk (France

    Directory of Open Access Journals (Sweden)

    Rabih Maamary

    2016-02-01

    Full Text Available A room-temperature continuous-wave (CW quantum cascade laser (QCL-based methane (CH4 sensor operating in the mid-infrared near 8 μm was developed for continuous measurement of CH4 concentrations in ambient air. The well-isolated absorption line (7F2,4 ← 8F1,2 of the ν4 fundamental band of CH4 located at 1255.0004 cm−1 was used for optical measurement of CH4 concentration by direct absorption in a White-type multipass cell with an effective path-length of 175 m. A 1σ (SNR = 1 detection limit of 33.3 ppb in 218 s was achieved with a measurement precision of 1.13%. The developed sensor was deployed in a campaign of measurements of time series CH4 concentration on a site near a suburban traffic road in Dunkirk (France from 9th to 22nd January 2013. An episode of high CH4 concentration of up to ~3 ppm has been observed and analyzed with the help of meteorological parameters combined with back trajectory calculation using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT model of NOAA.

  13. Tunable external cavity quantum cascade laser for the simultaneous determination of glucose and lactate in aqueous phase.

    Science.gov (United States)

    Brandstetter, Markus; Genner, Andreas; Anic, Kresimir; Lendl, Bernhard

    2010-12-01

    A room temperature operated pulsed external-cavity (EC) quantum cascade laser (QCL) was used for mid-infrared (mid-IR) transmission measurements of glucose and lactate in aqueous solution. The high spectral power density of the EC-QCL (ranging from 1-350 mW) over a wide tuning range (1030-1230 cm(-1)) allowed transmission measurements through optical paths of 130 μm and more. This is a significant improvement in terms of robustness of the measurement setup, especially when samples containing cells or other particles, as is the case for biofluids, are to be analyzed. The broad tuning range furthermore permitted multi-analyte detection based on multivariate calibrations. Promising results on the simultaneous determination of glucose (c = 0-800 mg dL(-1)) and sodium-lactate (c = 0-224 mg dL(-1)) in aqueous solutions in the presence of the interferents maltose and xylose are reported. A partial least squares (PLS) calibration model was calculated which was able to predict the glucose concentration with a root mean square error of prediction (RMSEP) of 9.4 mg dL(-1), as proved by external validation. Due to their small size and room temperature operation, EC-QCLs offer an attractive alternative regarding the way mid-IR measurements are carried out. This may be of special importance for new reagent-free bedside monitoring systems.

  14. High performance liquid chromatography with mid-infrared detection based on a broadly tunable quantum cascade laser.

    Science.gov (United States)

    Beskers, Timo F; Brandstetter, Markus; Kuligowski, Julia; Quintás, Guillermo; Wilhelm, Manfred; Lendl, Bernhard

    2014-05-07

    This work introduces a tunable mid-infrared (mid-IR) external cavity quantum cascade laser (EC-QCL) as a new molecular specific detector in liquid chromatography. An EC-QCL with a maximum tunability of 200 cm(-1) (1030-1230 cm(-1)) was coupled to isocratic high performance liquid chromatography (HPLC) for the separation of sugars with a cation exchange column (counter ion: Ca(2+)) and distilled water as the mobile phase. Transmission measurements in a 165 μm thick flow cell allowed for on-line coupling and independent quantification of glucose, fructose and sucrose in the concentration range from 5 mg mL(-1) to 100 mg mL(-1) in several beverages. The results obtained with the EC-QCL detector were found to be in good agreement with those obtained using a differential refractive index detector as a reference. The standard deviation of the method for the linear calibration was better than 5 mg mL(-1) for all sugars and reached a minimum of 1.9 mg mL(-1), while the DRI detector reached a minimum of 1 mg mL(-1). Besides the quantification of sugars for which a calibration was performed, also chromatographic peaks of other components could be identified on the basis of their IR absorption spectra. This includes taurine, ethanol, and sorbitol.

  15. High-Power Growth-Robust InGaAs/InAlAs Terahertz Quantum Cascade Lasers.

    Science.gov (United States)

    Deutsch, Christoph; Kainz, Martin Alexander; Krall, Michael; Brandstetter, Martin; Bachmann, Dominic; Schönhuber, Sebastian; Detz, Hermann; Zederbauer, Tobias; MacFarland, Donald; Andrews, Aaron Maxwell; Schrenk, Werner; Beck, Mattias; Ohtani, Keita; Faist, Jérôme; Strasser, Gottfried; Unterrainer, Karl

    2017-04-19

    We report on high-power terahertz quantum cascade lasers based on low effective electron mass InGaAs/InAlAs semiconductor heterostructures with excellent reproducibility. Growth-related asymmetries in the form of interface roughness and dopant migration play a crucial role in this material system. These bias polarity dependent phenomena are studied using a nominally symmetric active region resulting in a preferential electron transport in the growth direction. A structure based on a three-well optical phonon depletion scheme was optimized for this bias direction. Depending on the sheet doping density, the performance of this structure shows a trade-off between high maximum operating temperature and high output power. While the highest operating temperature of 155 K is observed for a moderate sheet doping density of 2 × 1010 cm-2, the highest peak output power of 151 mW is found for 7.3 × 1010 cm-2. Furthermore, by abutting a hyperhemispherical GaAs lens to a device with the highest doping level a record output power of 587 mW is achieved for double-metal waveguide structures.

  16. Suitability of quantum cascade laser spectroscopy for CH4 and N2O eddy covariance flux measurements

    Directory of Open Access Journals (Sweden)

    A. T. Vermeulen

    2007-08-01

    Full Text Available A quantum cascade laser spectrometer was evaluated for eddy covariance flux measurements of CH4 and N2O using three months of continuous measurements at a field site. The required criteria for eddy covariance flux measurements including continuity, sampling frequency, precision and stationarity were examined. The system operated continuously at a dairy farm on peat grassland in the Netherlands from 17 August to 6 November 2006. An automatic liquid nitrogen filling system for the infrared detector was employed to provide unattended operation of the system. The electronic sampling frequency was 10 Hz, however, the flow response time was 0.08 s, which corresponds to a bandwidth of 2 Hz. A precision of 2.9 and 0.5 ppb Hz−1/2 was obtained for CH4 and N2O, respectively. Accuracy was assured by frequent calibrations using low and high standard additions. Drifts in the system were compensated by using a 120 s running mean filter. The average CH4 and N2O exchange was 512 ngC m−2 s−1 (2.46 mg m−2 hr−1 and 52 ngN m−2 s−1 (0.29 mg m−2 hr−1. Given that 40% of the total N2O emission was due to a fertilizing event.

  17. A quartz enhanced photo-acoustic gas sensor based on a custom tuning fork and a terahertz quantum cascade laser.

    Science.gov (United States)

    Patimisco, Pietro; Borri, Simone; Sampaolo, Angelo; Beere, Harvey E; Ritchie, David A; Vitiello, Miriam S; Scamarcio, Gaetano; Spagnolo, Vincenzo

    2014-05-07

    An innovative quartz enhanced photoacoustic (QEPAS) gas sensing system operating in the THz spectral range and employing a custom quartz tuning fork (QTF) is described. The QTF dimensions are 3.3 cm × 0.4 cm × 0.8 cm, with the two prongs spaced by ∼800 μm. To test our sensor we used a quantum cascade laser as the light source and selected a methanol rotational absorption line at 131.054 cm(-1) (∼3.93 THz), with line-strength S = 4.28 × 10(-21) cm mol(-1). The sensor was operated at 10 Torr pressure on the first flexion QTF resonance frequency of 4245 Hz. The corresponding Q-factor was 74 760. Stepwise concentration measurements were performed to verify the linearity of the QEPAS signal as a function of the methanol concentration. The achieved sensitivity of the system is 7 parts per million in 4 seconds, corresponding to a QEPAS normalized noise-equivalent absorption of 2 × 10(-10) W cm(-1) Hz(-1/2), comparable with the best result of mid-IR QEPAS systems.

  18. GaAs/A1GaAs microresonator quantum cascade lasers

    Science.gov (United States)

    Gianordoli, S.; Hvozdara, L.; Strasser, G.; Maier, T.; Finger, N.; Unterrainer, K.; Gornik, E.

    2000-03-01

    We report on the realization of electrically pumped GaAs/AlGaAs microcylinder lasers emitting at λ=10 μm. The design and fabrication process of the special resonator shapes (circular- and stadium-like cross section) are presented. The active material is a 30 period sequence of injectors/active regions made of GaAs/AlGaAs quantum wells. Far-field characteristics of these special resonators are compared and the dependence of directionality of the emission on the deformation is investigated. The bow-tie mode can be resolved in the far-field pattern. A transition from the bow-tie to another mode with highly directional emission along the short axis of the resonators is shown for the first time. Single-mode emission is detected for 100 μm diameter circular microlasers with a side mode suppression exceeding 20 dB. The maximum working temperature of the microcylinder lasers is 165 K.

  19. Femtosecond laser's application in the corneal surgery

    Directory of Open Access Journals (Sweden)

    Shu-Liang Wang

    2015-10-01

    Full Text Available With the rapid development over the past two decades,femtosecond(10-15slasers(FShas become a new application in ophthalmic surgery. As laser power is defined as energy delivered per unit time, decreasing the pulse duration to femtosecond level(100fsnot only increases the power delivered but also decreases the fluence threshold for laser induced optical breakdown. In ablating tissue, FS has an edge over nanosecond lasers as there is minimal collateral damage from shock waves and heat conduction during surgical ablation. Thus, application of FS has been widely spread, from flap creation for laser-assisted in situ keratomileusis(LASIKsurgery, cutting of donor and recipient corneas in keratoplasty, creation of pockets for intracorneal ring implantation. FS applied in keratoplasty is mainly used in making graft and recipient bed, and can exactly cut different tissue of keratopathy. FS can also cut partial tissue of cornea, even if it is under the moderate corneal macula and corneal edema condition.

  20. Design of the improved cascade ADRC and its application in photoelectric tracking system

    Science.gov (United States)

    Zuo, Dan; Tang, Tao; Huang, Yongmei; Cai, Huaxiang

    2015-10-01

    According to the larger error when reversing in photoelectric tracking control system, the improved cascade Active Disturbance Rejection Controller (ADRC) is put forward to improve the system position tracking performance and tracking precision. First of all, this essay analyses the controlled object model and system control strategy; Then, it gives design method of the improved cascade ADRC; Finally, in order to analyses the improved cascade's better control performance, in the condition of the same input signal ,the improved cascade ADRC, conventional ADRC-ADRC and traditional PI-PI controller are used in photoelectric tracking control system to do comparative experiment. The experiment results show that the improved cascade ADRC's performance is better than other two algorithms, the tracking error and the steady state mean square error are significantly reduced, tracking accuracy is significantly improved. The improved cascade ADRC is an appealing solution in dealing with industrial control system problems where uncertainties and interference abound.

  1. Low voltage ride through peformance of a STATCOM based on modular multilevel cascade converters for offshore wind application

    DEFF Research Database (Denmark)

    Tanaka, Takaaki; Wang, Huai; Ma, Ke

    2017-01-01

    Static Synchronous Compensators (STATCOMs) are being applied for offshore wind power plants to satisfy the grid codes under both normal operation and grid fault conditions. This paper investigates the performances of Modular Multilevel Cascade Converters (MMCC) for the STATCOM application, with s...

  2. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Chen, Zhe; Deng, Fujin

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able......, and this responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  3. Adaptive micro axicons for laser applications

    Directory of Open Access Journals (Sweden)

    Wallrabe Ulrike

    2015-01-01

    Full Text Available We report on the design, fabrication and testing of novel types of low-dispersion axicons for the adaptive shaping of ultrashort laser pulses. An overview is given on the basic geometries and operating principles of our purely reflective adaptive MEMS-type devices based on thermal or piezoelectric actuation. The flexible formation of nondiffracting beams at pulse durations down to a few oscillations of the optical field enables new applications in optical communication, pulse diagnostics, laser-matter interaction and particle manipulation. As an example, we show first promising results of adaptive autocorrelation. The combination of excellent pulse transfer, self-reconstruction properties and propagation invariance of nondiffracting beams with an adaptive approach promises to extend the field of practical applications significantly.

  4. Femtosecond laser application in biotechnology and medicine

    Science.gov (United States)

    Koenig, Karsten

    2004-10-01

    Near-infrared (NIR) 80 MHz nanojoule femtosecond laser pulses of low sub-nanojoule and nJ pulse energies in combination with focusing optics of high numerical aperture can be used as versatile multiphoton tools in nanobiotechnology and nano/micro-medicine. Novel diagnostic applications include gene imaging by multiphoton multicolor FISH (MM-FISH) and high-resolution multiphoton tomography of skin as well as tissue engineered cardiovascular structures based on two-photon autofluorescence excitation and second harmonic generation (SHG) of endogenous biomolecules. Using high-intense (1011 - 1012 W/cm2) 80 MHz femtosecond laser beams, non-invasive targeted transfection of mammalian cells with DNA can be realized by creation of highly localized membrane perforations. Nanosurgery can be performed by optical knocking out of intracellular and intratissue structures. Potential applications include gene and cancer therapy, eye and brain surgery as well as optical engineering of single DNA molecules as key elements in bionanotechnology.

  5. Applications of laser techniques in fluid mechanics

    Science.gov (United States)

    Chan, W. K.; Liu, C. Y.; Wong, Y. W.

    1991-03-01

    Three examples of different applications of laser techniques in experimental fluid mechanics are described including flow field around a proposed heart prostheses, flow field around a model motor vehicle, and flow visualization of the vortex shedding from a delta wing. Velocity measurements of flow around the heart valve prosthesis indicate that the new design is capable of delaying flow separation. Velocity measurements of flow around a model motor vehicle show that separation occurs above the bonnet and at the rear of the vehicle.

  6. Adaptive micro axicons for laser applications

    OpenAIRE

    Wallrabe Ulrike; Brunne Jens; Treffer Alexander; Grunwald Ruediger

    2015-01-01

    We report on the design, fabrication and testing of novel types of low-dispersion axicons for the adaptive shaping of ultrashort laser pulses. An overview is given on the basic geometries and operating principles of our purely reflective adaptive MEMS-type devices based on thermal or piezoelectric actuation. The flexible formation of nondiffracting beams at pulse durations down to a few oscillations of the optical field enables new applications in optical communication, pulse diagnostics, las...

  7. Characterizing a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of atmospheric ammonia

    Directory of Open Access Journals (Sweden)

    R. A. Ellis

    2010-03-01

    Full Text Available A compact, fast-response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS for measurements of ammonia (NH3 has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 0.5 L multiple pass absorption cell with an effective path length of 76 m. Detection is achieved using a thermoelectrically-cooled Mercury Cadmium Telluride (HgCdTe infrared detector. A novel sampling inlet was used, consisting of a short, heated, quartz tube with a hydrophobic coating to minimize the adsorption of NH3 to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles, and additional ports for delivering NH3-free background air and calibration gas standards. The level of noise in this instrument has been found to be 0.23 ppb at 1 Hz. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser Absorption Spectrometer (TDLAS during a laboratory intercomparison. The effect of humidity and heat on the surface interaction of NH3 with sample tubing was investigated at mixing ratios ranging from 30–1000 ppb. Humidity was seen to worsen the NH3 time response and considerable improvement was observed when using a heated sampling line. A field intercomparison of the QC-TILDAS with a modified Thermo 42CTL chemiluminescence-based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE in the rural town of Egbert, ON between May–July 2008. Background tests and calibrations using two different permeation tube sources and an NH3 gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation at 1 min time resolution (R2 = 0.93 between the two instruments at the

  8. Application of Low level Lasers in Dentistry (Endodontic)

    Science.gov (United States)

    Asnaashari, Mohammad; Safavi, Nassimeh

    2013-01-01

    Low level lasers, cold or soft lasers: These lasers do not produce thermal effects on tissues and induce photoreactions in cells through light stimulation which is called photobiostimulation. Power of these lasers is usually under 250mW. The main point differentiating low level lasers and high power ones is the activation of photochemical reactions without heat formation. The most important factor to achieve this light characteristic in lasers is not their power, but their power density for each surfa ceunit (i.e cm2). Density lower than 670mW/cm2, can induce the stimulatory effects of low level lasers without thermal effects. Low level lasers (therapeutic) used today as treatment adjunctive devices in medicine and dentistry. Numerous studies have been performed on the applications of low level lasers in patient pain reduction. Mechanisms of pain reduction with therapeutic lasers and their application are expressed, and the studies realized in this field are presented. PMID:25606308

  9. Application of Low level Lasers in Dentistry (Endodontic).

    Science.gov (United States)

    Asnaashari, Mohammad; Safavi, Nassimeh

    2013-01-01

    Low level lasers, cold or soft lasers: These lasers do not produce thermal effects on tissues and induce photoreactions in cells through light stimulation which is called photobiostimulation. Power of these lasers is usually under 250mW. The main point differentiating low level lasers and high power ones is the activation of photochemical reactions without heat formation. The most important factor to achieve this light characteristic in lasers is not their power, but their power density for each surfa ceunit (i.e cm(2)). Density lower than 670mW/cm(2), can induce the stimulatory effects of low level lasers without thermal effects. Low level lasers (therapeutic) used today as treatment adjunctive devices in medicine and dentistry. Numerous studies have been performed on the applications of low level lasers in patient pain reduction. Mechanisms of pain reduction with therapeutic lasers and their application are expressed, and the studies realized in this field are presented.

  10. High Power Fiber Lasers and Applications to Manufacturing

    Science.gov (United States)

    Richardson, Martin; McComb, Timothy; Sudesh, Vikas

    2008-09-01

    We summarize recent developments in high power fiber laser technologies and discuss future trends, particularly in their current and future use in manufacturing technologies. We will also describe our current research programs in fiber laser development, ultra-fast and new lasers, and will mention the expectations in these areas for the new Townes Laser Institute. It will focus on new core laser technologies and their applications in medical technologies, advanced manufacturing technologies and defense applications. We will describe a program on large mode area fiber development that includes results with the new gain-guiding approach, as well as high power infra-red fiber lasers. We will review the opportunities for high power fiber lasers in various manufacturing technologies and illustrate this with applications we are pursuing in the areas of femtosecond laser applications, advanced lithographies, and mid-IR technologies.

  11. Long Path Quantum Cascade Laser Based Sensor for Environment Sensing/Ambient Detection of CH4 and N2O

    Science.gov (United States)

    Castillo, P. C.; Sydoryk, I.; Gross, B.; Moshary, F.

    2013-12-01

    Methane (CH4) and Nitrous Oxide (N2O) are long-lived greenhouse gases in the atmosphere with significant global warming effects. These gases also are known to be produced in a number of anthropogenic settings such as manure management systems, which releases substantial GHGs and is mandated by the EPA to provide continuous monitoring. In addition, natural gas leaks in urban areas is another source of strong spatially inhomogeneous methane emissions Most open path methods for quantitative detection of trace gases utilize either Fourier Transform Spectrometer (FTIR) or near-IR differential optical absorption spectroscopy (DOAS). Although, FTIR is suitable for ambient air monitoring measurement of more abundant gases such as CO2 and H20 etc., the lack of spectral resolution makes the retrieval of weaker absorbing features such as N20 more difficult. On the other hand, conventional DOAS systems can be large and impractical. As an alternative, we illustrate a robust portable quantum cascade laser (QCL) approach for simultaneous detection of CH4 and N2O. In particular, gas spectra were recorded by ultrafast pulse intensity (thermal) chirp tuning over the 1299 - 1300cm-1 spectral window. Etalon measurements insure stable tuning was obtained. To deal with multiple species, a LSQ spectral fitting approach was used which accounted for both the overlapping trace gases , background water vapor as well as detector drift and calibration. In summary, ambient concentrations of CH4 with and N2O with accuracy < 1% was obtained on the order of 5ms using optical paths of 500 m path length. In addition, unattended long term operation was demonstrated and validations using other sensors when possible were shown to be consistent. The system accuracy is limited by systemic errors, which are still being explored.

  12. Generation and Amplification of Tunable Multicolored Femtosecond Laser Pulses by Using Cascaded Four-Wave Mixing in Transparent Bulk Media

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2010-04-01

    Full Text Available We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1 as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm to near infrared (1.2 μm; (2 the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3 the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4 as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5 the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6 broadband two-dimensional (2-D multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7 the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM in conjunction with four-wave optical parametric amplification (FOPA. The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy.

  13. Mapping Atmospheric Ammonia Emissions Using a Mobile Quantum Cascade Laser-based Open-path Sensor

    Science.gov (United States)

    Sun, K.; Tao, L.; Miller, D. J.; Khan, M. A.; Zondlo, M. A.

    2012-12-01

    Ammonia (NH3) is a key precursor to atmospheric fine particulate matter, with strong implications for regional air quality and global climate change. Despite the importance of atmospheric ammonia, its spatial/temporal variation is poorly characterized, and the knowledge of its sources, sinks, and transport is severely limited. Existing measurements suggest that traffic exhaust may provide significant amounts of ammonia in urban areas, which cause greater impacts on particulate matter formation and urban air quality. To capture the spatial and temporal variation of ammonia emissions, a portable, low power sensor with high time resolution is necessary. We have developed a portable open-path ammonia sensor with a detection limit of 0.5 ppbv ammonia for 1 s measurements. The sensor has a power consumption of about 60 W and is capable of running on a car battery continuously for 24 hours. An additional laser has been coupled to the sensor to yield concurrent N2O and CO measurements as tracers for determining various sources. The overall sensor prototype fits on a 60 cm × 20 cm aluminum breadboard. Roadside measurements indicated NH3/CO emission ratios of 4.1±5.4 ppbv/ppmv from a fleet of 320 vehicles, which agree with existing on-ramp measurements. Urban measurements in the Baltimore and Washington, DC metropolitan areas have shown significant ammonia mixing ratios concurrent with carbon monoxide levels from the morning and evening rush hours. On-road measurements of our open-path sensor have also been performed continuously from the Midwest to Princeton, NJ including urban areas such as Pittsburgh, tunnels, and relatively clean conditions. The emission ratios of ammonia against CO and/or CO2 help identify the sources and amounts of both urban and agricultural ammonia emissions. Preliminary data from both spatial mapping, monitoring, and vehicle exhaust measurements suggest that urban ammonia emissions from fossil fuel combustion are significant and may provide an

  14. Fast in situ airborne and ground-based flux measurement of ammonia using a quantum cascade laser spectrometer

    Science.gov (United States)

    Leen, J. B.; Yu, X.; Hubbe, J.; Kluzek, C. D.; Tomlinson, J. M.; Fischer, M. L.; Reichl, K.; Gupta, M.

    2012-12-01

    A pair of new ammonia (NH3) spectrometers were developed based on off-axis integrated cavity output spectroscopy. These ammonia gas analyzers consist of an optical cell, a quantum-cascade laser, a HgCdTe detector, gas sampling system, electronics for control and data acquisition, and data-analysis software. The NH3 mixing ratio is determined from high-resolution NH3 absorption line shapes by tuning the laser wavelength over the fundamental vibration band near 9.6 μm. Excellent linearity is obtained in a wide range (0- 500 ppb) with a precision of 75 ppt (1σ in 1 second). The analyzers' 1/e response time to step changes in ammonia concentration are 2.4 Hz and 8.1 Hz for the airborne and flux instruments, respectively. Feasibility was demonstrated in airborne test flights in the troposphere on board of the Department of Energy (DOE) Gulfstream-1 (G-1) aircraft. Two research flights were conducted over Sunnyside, Washington. In the first test flight, the ammonia gas sensor was used to identify signatures of feedstock from local dairy farms with high vertical spatial resolution under low wind and stable atmospheric conditions. In the second flight, the NH3 spectrometer showed high sensitivity in capturing feedstock emission signals under windy and less stable conditions. Mixing ratios aloft were measured between 0.75 ppb above the boundary layer and 100 ppb over large feedlots. Eddy covariance estimates of NH3 flux from a manure slurry amendment were performed in a pasture near Two Rock, California from May 18, 2012 to July 5, 2012. Measurement spanned pasture conditions from forage growth, cut-to-ground, manure slurry amendment (estimated to be 95 ± 33% kg NH3-N ha-1) and re-growth. An exponential decay fit to the NH3 flux data after slurry amendment provides an estimate of cumulative emission of 6.6 ± 0.5 kg NH3-N ha-1 (or 7 ± 0.24% of the total applied nitrogen) as a result of the slurry amendment. These results demonstrate that the new ammonia spectrometers

  15. [Basic principles and clinical application of retinal laser therapy].

    Science.gov (United States)

    Framme, C; Roider, J; Brinkmann, R; Birngruber, R; Gabel, V-P

    2008-04-01

    The scientific background of laser photocoagulation of the ocular fundus was studied extensively by several investigators in the 1970 s and 1980 s. The basic principles were successfully resolved during that time and clinical consequences for proper application of the laser photocoagulation for various diseases were deduced. The present paper gives an overview about the physical basics of laser-tissue interactions during and after retinal laser treatment and the particular laser strategies in the treatment of different retinal diseases. Thus, it addresses the issue of the impact on tissue of laser parameters as wavelength, spot size, pulse duration and laser power. Additionally, the different biological tissue reactions after laser treatment are presented, such as, e. g., for retinopexia or macular treatments as well as for diabetic retinopathies. Specific laser strategies such as the selective laser treatment of the RPE (SRT) or the transpupillary thermotherapy (TTT) are presented and discussed.

  16. Gigabit radio-over-fiber link for converged baseband and millimeter-wave band signal transmission using cascaded injection-locked Fabry-Pérot laser diodes.

    Science.gov (United States)

    Hong, Moon-Ki; Won, Yong-Yuk; Han, Sang-Kook

    2009-05-11

    A novel scheme, for both baseband and millimeter-wave band gigabit data transmission in radio-over-fiber system, is proposed and experimentally demonstrated by using cascaded injection-locked Fabry- Pérot laser diodes. It was able to improve suppression ratio of carrier suppressed signal using the cascaded injection-locking. The suppression ratio improvement of the optical carrier suppressed signal of 20 dB was verified. Applying this mechanism, 60-GHz millimeter-wave carrier of enhanced signal quality could be accomplished. Its peak power and phase noise were obtained as -40 dBm and -103.5 dBm/Hz respectively, which was suitable for 60-GHz data transmission. In addition, a successful bidirectional transmission of 1.25-Gbps wired and wireless data was achieved by adopting remodulation technique using a gain-saturated reflective semiconductor optical amplifier for uplink.

  17. Shifted laser surface texturing for bearings applications

    Science.gov (United States)

    Houdková, Š.; Šperka, P.; Repka, M.; Martan, J.; Moskal, D.

    2017-05-01

    The laser surface texturing (LST) technologies, based on creation of micro-pattern with pre-defined geometry can positively influence both the friction and wear of tribo-elements. In practice, the integration of LST technology is often limited due to its slowness. The new method, so called shifted laser surface texturing (sLST) with increased process speed was developed to make the technology more attractive for the industrial application. In the paper, the texture created by sLST technology was applied onto the steel samples and Al-Sn-Si surface of sliding bearings. Both block-on-ring (ASTM G-77) laboratory tests of steel samples and high-loaded working application tests on Al-Sn-Si bearings surface were carried out to evaluate the influence of texture on tribological behaviour. The ASTM G-77 laboratory tests showed a positive effect of the texture on friction behaviour. Under the high-loaded testing conditions, the positive effect was observed in initial stages of the tests, decreasing the torque of textured bearings compared to the untreated one. Lately, the texture was worn out and have no influence on the overall wear of the bearings. Based on the above mentioned observations, the use of alternative bearing material with higher hardness or application of protective layer over the created texture was suggested to exploit the texture benefits.

  18. 3D laser microfabrication principles and applications

    CERN Document Server

    Misawa, Hiroaki

    2006-01-01

    A thorough introduction to 3D laser microfabrication technology, leading readers from the fundamentals and theory to its various potent applications, such as the generation of tiny objects or three-dimensional structures within the bulk of transparent materials. The book also presents new theoretical material on dielectric breakdown, allowing a better understanding of the differences between optical damage on surfaces and inside the bulk, as well as a look into the future.Chemists, physicists, materials scientists and engineers will find this a valuable source of interdisciplinary know

  19. Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H2S measurements in a petrochemical process gas stream.

    Science.gov (United States)

    Moser, Harald; Pölz, Walter; Waclawek, Johannes Paul; Ofner, Johannes; Lendl, Bernhard

    2017-01-01

    The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8-μm continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H2S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH4) matrix of up to 1000 ppmv together with a varying H2S content was chosen as the model environment for the laboratory-based performance evaluation performed at TU Wien. A noise-equivalent absorption sensitivity (NEAS) for H2S targeting the absorption line at 1247.2 cm(-1) was found to be 8.419 × 10(-10) cm(-1) Hz(-1/2), and a limit of detection (LOD) of 150 ppbv H2S could be achieved. The sensor prototype was then deployed for on-site measurements at the petrochemical research hydrogenation platform of the industrial partner OMV AG. In order to meet the company's on-site safety regulations, the H2S sensor platform was installed in an industry rack and equipped with the required safety infrastructure for protected operation in hazardous and explosive environments. The work reports the suitability of the sensor prototype for simultaneous monitoring of H2S and CH4 content in the process streams of a research hydrodesulfurization (HDS) unit. Concentration readings were obtained every 15 s and revealed process dynamics not observed previously.

  20. Combining an automated closed chamber system with a quantum cascade laser for high-frequency measurements of δ13C of ecosystem CO2 fluxes

    Science.gov (United States)

    Brændholt, Andreas; Ibrom, Andreas; Ambus, Per; Steenberg Larsen, Klaus; Pilegaard, Kim

    2017-04-01

    Advances in laser spectroscopy have allowed for online high-frequency measurements of the isotopic composition of C and O in CO2, thereby providing new ways to investigate CO2 flux partitioning and carbon cycling in natural ecosystems. In this study, we combined an Aerodyne quantum cascade laser for CO2 isotopes with the LI-COR LI-8100A/8150 automatic closed chamber system to yield the δ13C of CO2 during automated closed chamber measurements. The system was used during a two month campaign in a Danish beech forest, where δ13C was measured for a total of 12 chambers, each enclosing either intact soil, trenched soil, tree stem or a tree root. By applying the Keeling plot methodology to the change in δ13C of CO2 during a chamber measurement, the isotopic composition of the respired CO2 was determined. The poster presents δ13C data of ecosystem CO2 fluxes on both a daily and diel scale for soil, roots and tree stems that revealed interesting information about forest ecosystem carbon cycling. Furthermore, it explores the unique setup and the tests required for precise automated chamber-based measurements of δ13C by a quantum cascade laser. Acknowledgements: This study was funded by the free Danish Ministry for Research, Innovation and higher Education, the free Danish Research Council (DFF - 1323-00182).

  1. Laser surface treatment of grey cast iron for automotive applications

    NARCIS (Netherlands)

    Ocelik, V.; Tang, P.N.; de Boer, M.C.; de Oliveira, U.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    The surface of pearlitic grey cast iron was treated using a 2 kW Nd:YAG laser beam with the final aim to improve its surface properties, mainly for automotive applications. Two kinds of laser surface treatments were experimentally applied. In the laser surface hardening approach the surface of cast

  2. Diode pumped solid-state laser oscillators for spectroscopic applications

    Science.gov (United States)

    Byer, R. L.; Basu, S.; Fan, T. Y.; Kozlovsky, W. J.; Nabors, C. D.; Nilsson, A.; Huber, G.

    1987-01-01

    The rapid improvement in diode laser pump sources has led to the recent progress in diode laser pumped solid state lasers. To date, electrical efficiencies of greater than 10 percent were demonstrated. As diode laser costs decrease with increased production volume, diode laser and diode laser array pumped solid state lasers will replace the traditional flashlamp pumped Nd:YAG laser sources. The use of laser diode array pumping of slab geometry lasers will allow efficient, high peak and average power solid state laser sources to be developed. Perhaps the greatest impact of diode laser pumped solid state lasers will be in spectroscopic applications of miniature, monolithic devices. Single-stripe diode-pumped operation of a continuous-wave 946 nm Nd:YAG laser with less than 10 m/w threshold was demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. The KNbO3 and periodically poled LiNbO3 appear to be the most promising.

  3. Paediatric laser dentistry. Part 2: Hard tissue laser applications.

    Science.gov (United States)

    Olivi, G; Caprioglio, C; Olivi, M; Genovese, M D

    2017-06-01

    Erbium lasers can provide effective and minimally invasive caries removal in children. The bonding phase remains a critic step as well as the choice of material. Glass ionomers exhibits lower bonding properties in laser irradiated teeth compared to the conventional method or to composite and resin modified glass ionomer. Laser can also provide effective decontamination and coagulation effects in vital and non vital pulp therapy of primary teeth, improving and simplifying the cleaning and disinfecting steps.

  4. Femtosecond laser-matter interaction theory, experiments and applications

    CERN Document Server

    Gamaly, Eugene G

    2011-01-01

    Basics of Ultra-Short Laser-Solid InteractionsSubtle Atomic Motion Preceding a Phase Transition: Birth, Life and Death of PhononsUltra-Fast Disordering by fs-Lasers: Superheating Prior to Entropy CatastropheAblation of SolidsUltra-Short Laser-Matter Interaction Confined Inside a Bulk of Transparent SolidApplications of Ultra-Short Laser-Matter InteractionsConclusion Remarks.

  5. Gigabit free-space multi-level signal transmission with a mid-infrared quantum cascade laser operating at room temperature

    OpenAIRE

    Pang, Xiaodan; Ozolins, Oskars; Schatz, Richard; Storck, Joakim; Udalcovs, Aleksejs; Navarro, Jaime Rodrigo; Kakkar, Aditya; Maisons, Gregory; Carras, Mathieu; Jacobsen, Gunnar; Popov, Sergei; Lourdudoss, Sebastian

    2017-01-01

    Gigabit free-space transmissions are experimentally demon-strated with a quantum cascaded laser (QCL) emitting at mid-wavelength infrared of 4.65 mu m, and a commercial infrared photovoltaic detector. The QCL operating at room temperature is directly modulated using on - off keying and, for the first time, to the best of our knowledge, four-and eight-level pulse amplitude modulations (PAM-4, PAM-8). By applying pre- and post-digital equalizations, we achieve up to 3 Gbit/s line data rate in a...

  6. Observation of infrared free-induction decay and optical nutation signals from nitrous oxide using a current modulated quantum cascade laser.

    Science.gov (United States)

    Duxbury, Geoffrey; Kelly, James F; Blake, Thomas A; Langford, Nigel

    2012-05-07

    Free induction decay (FID), optical nutation, and rapid passage induced signals in nitrous oxide, under both optically thin and optically thick conditions, have been observed using a rapid current pulse modulation, or chirp, applied to the slow current ramp of a quantum cascade (QC) laser. The variation in optical depth was achieved by increasing the pressure of nitrous oxide in a long path length multipass absorption cell. This allows the variation of optical depth to be achieved over a range of low gas pressures. Since, even at the highest gas pressure used in the cell, the chirp rate of the QC laser is faster than the collisional reorientation time of the molecules, there is minimal collisional damping, allowing a large macroscopic polarization of the molecular dipoles to develop. This is referred to as rapid passage induced polarization. The resultant FID signals are enhanced due to the constructive interference between the field within the gas generated by the slow ramp of the laser (pump), and that of the fast chirp of the laser (probe) signal generated by pulse modulation of the continuously operating QC laser. The FID signals obtained at large optical depth have not been observed previously in the mid-infrared regions, and unusual oscillatory signals have been observed at the highest gas pressures used.

  7. Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

    Science.gov (United States)

    Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

    2014-02-10

    We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

  8. Laser wakefield accelerator based light sources: potential applications and requirements

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  9. Absolute spectroscopy near 7.8 μm with a comb-locked extended-cavity quantum-cascade-laser

    KAUST Repository

    Lamperti, Marco

    2018-01-16

    We report for the first time the frequency locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locked laser source is exploited to carry out molecular spectroscopy around 7.8 μm with a line-centre frequency combined uncertainty of ~63 kHz. The strength of the approach, in view of an accurate retrieval of line centre frequencies over a spectral range as large as 100 cm-1, is demonstrated on the P(40), P(18) and R(31) lines of the fundamental rovibrational band of N2O covering the centre and edges of the P and R branches. The spectrometer has the potential to be straightforwardly extended to other spectral ranges, till 12 μm, which is the current wavelength limit for commercial cw EC-QCLs.

  10. High power, widely tunable, mode-hop free, continuous wave external cavity quantum cascade laser for multi-species trace gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Centeno, R.; Marchenko, D.; Mandon, J.; Cristescu, S. M.; Harren, F. J. M., E-mail: F.Harren@science.ru.nl [Life Science Trace Gas Facility, Molecular and Laser Physics, Institute for Molecules and Materials, Radboud University, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Wulterkens, G. [TechnoCentrum, Radboud University, Heyendaalseweg 135, 6525AJ Nijmegen (Netherlands)

    2014-12-29

    We present a high power, widely tunable, continuous wave external cavity quantum cascade laser designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features. The laser source exhibits single mode operation with a tunability up to 303 cm{sup −1} (∼24% of the center wavelength) at 8 μm, with a maximum optical output power of 200 mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of 3.7 × 10{sup −8 }cm{sup −1 }Hz{sup −1/2} was obtained.

  11. High power single frequency 780nm laser source generated from frequency doubling of a seeded fiber amplifier in a cascade of PPLN crystals.

    Science.gov (United States)

    Thompson, R; Tu, M; Aveline, D; Lundblad, N; Maleki, L

    2003-07-14

    We report on the generation of over 900 mW of tunable cw light at 780 nm by single pass frequency doubling of a high power fiber amplifier in a cascade of two periodically poled Lithium Niobate (PPLN) crystals. Over 500 mW is generated in the first crystal. In the limit of low pump power, we observe an efficiency of 4.6 mW/W2-cm for a single crystal, and 5.6 mW/W2-cm for a combination of two crystals, with an enhancement of the doubling efficiency observed with two crystals due to the presence of second harmonic light from the first crystal acting as a seed for the second. We have frequency locked this laser source relative to a rubidium D2 hyperfine line and demonstrated its utility in a sophisticated laser cooling apparatus.

  12. Part-Per-Trillion Level SF6 Detection Using a Quartz Enhanced Photoacoustic Spectroscopy-Based Sensor with Single-Mode Fiber-Coupled Quantum Cascade Laser Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Spagnolo, V.; Patimisco, P.; Borri, Simone; Scamarcio, G.; Bernacki, Bruce E.; Kriesel, J.M.

    2012-10-23

    A sensitive spectroscopic sensor based on a hollow-core fiber-coupled quantum cascade laser (QCL) emitting at 10.54 µm and quartz enhanced photoacoustic spectroscopy (QEPAS) technique is reported. The design and realization of mid-infrared fiber and coupler optics has ensured single-mode QCL beam delivery to the QEPAS sensor . The collimation optics was designed to produce a laser beam of significantly reduced beam size and waist so as to prevent illumination of the quartz tuning fork and micro-resonator tubes. SF6 was selected as the target gas. A minimum detection sensitivity of 50 parts per trillion in 1 s was achieved with a QCL power of 18 mW, corresponding to a normalized noise-equivalent absorption of 2.7x10-10 W•cm-1/Hz1/2.

  13. Part-per-trillion level SF6 detection using a quartz enhanced photoacoustic spectroscopy-based sensor with single-mode fiber-coupled quantum cascade laser excitation.

    Science.gov (United States)

    Spagnolo, Vincenzo; Patimisco, Pietro; Borri, Simone; Scamarcio, Gaetano; Bernacki, Bruce E; Kriesel, Jason

    2012-11-01

    A sensitive spectroscopic sensor based on a hollow-core fiber-coupled quantum cascade laser (QCL) emitting at 10.54 μm and quartz enhanced photoacoustic spectroscopy (QEPAS) technique is reported. The design and realization of mid-IR fiber and coupler optics has ensured single-mode QCL beam delivery to the QEPAS sensor. The collimation optics was designed to produce a laser beam of significantly reduced beam size and waist so as to prevent illumination of the quartz tuning fork and microresonator tubes. SF(6) was selected as the target gas. A minimum detection sensitivity of 50 parts per trillion in 1 s was achieved with a QCL power of 18 mW, corresponding to a normalized noise-equivalent absorption of 2.7×10(-10) W·cm(-1)/Hz(1/2).

  14. CERN's web application updates for electron and laser beam technologies

    CERN Document Server

    Sigas, Christos

    2017-01-01

    This report describes the modifications at CERN's web application for electron and laser beam technologies. There are updates at both the front and the back end of the application. New electron and laser machines were added and also old machines were updated. There is also a new feature for printing needed information.

  15. Diode laser application in soft tissue oral surgery.

    Science.gov (United States)

    Azma, Ehsan; Safavi, Nassimeh

    2013-01-01

    Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity. Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation. The diode laser can be used as a modality for oral soft tissue surgery.

  16. Tunable lasers and their application in analytical chemistry

    Science.gov (United States)

    Steinfeld, J. I.

    1975-01-01

    The impact that laser techniques might have in chemical analysis is examined. Absorption, scattering, and heterodyne detection is considered. Particular emphasis is placed on the advantages of using frequency-tunable sources, and dye solution lasers are regarded as the outstanding example of this type of laser. Types of spectroscopy that can be carried out with lasers are discussed along with the ultimate sensitivity or minimum detectable concentration of molecules that can be achieved with each method. Analytical applications include laser microprobe analysis, remote sensing and instrumental methods such as laser-Raman spectroscopy, atomic absorption/fluorescence spectrometry, fluorescence assay techniques, optoacoustic spectroscopy, and polarization measurements. The application of lasers to spectroscopic methods of analysis would seem to be a rewarding field both for research in analytical chemistry and for investments in instrument manufacturing.

  17. X-ray Production by Cascading Stages of a High-Gain Harmonic Generation Free-Electron Laser II: Special Topics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J

    2004-09-01

    In this paper, we study the tolerance of a new approach to produce coherent x-ray by cascading several stages of a High-Gain Harmonic Generation (HGHG) Free-Electron Laser (FEL). Being a harmonic generation process, a small noise in the initial fundamental signal will lead to a significant noise-to-signal (NTS) ratio in the final harmonic, so the noise issue is studied in this paper. We study two sources of noise: the incoherent undulator radiation, which is a noise with respect to the seed laser; and the noise of the seed laser itself. In reality, the electron beam longitudinal current profile is not uniform. Since the electron beam is the amplification medium for the FEL, this non- uniformity will induce phase error in the FEL. Therefore, this effect is studied. Phase error due to the wakefield and electron beam self-field is also studied. Synchrotronization of the electron beam and the seed laser is an important issue determining the success of the HGHG. We study the timing jitter induced frequency jitter in this paper. We also show that an HGHG FEL poses a less stringent requirement on the emittance than a SASE FEL does, due to a Natural Emittance Effect Reduction (NEER) mechanism. This NEER mechanism suggests a new operation mode, i.e., the HGHG FEL could adopt a high current, though unavoidable, a high emittance electron beam. Study in this paper shows that, production of hard x-rays with good longitudinal coherence by cascading stages of a HGHG FEL is promising. However, technical improvement is demanded.

  18. Laser applications in oral surgery and implant dentistry.

    Science.gov (United States)

    Deppe, Herbert; Horch, Hans-Henning

    2007-11-01

    Lasers have been used for many years in oral surgery and implant dentistry. In some indications, laser treatment has become state of the art as compared to conventional techniques. This article is a comprehensive review of new laser applications in oral surgery and implant dentistry. One of the most interesting developments over the last years was the introduction of the 9.6-microm CO(2) laser. It has been shown in the recent literature that the use of this new device can preserve tissue with almost no adverse effects at the light microscopic level. In contrast, modifications of approved CO(2) laser therapies of premalignant lesions resulted in higher recurrence rates than the conventional defocused laser technique. However, several studies indicate that other wavelengths such as Nd-YAG (lambda = 1,064 nm) or diode lasers (lambda = 810 nm) may be also of value in this field. In many other indications, the use of lasers is still experimental. Intraoperatively used photodynamic therapy or peri-implant care of ailing implants with the CO(2) laser seems to be more of value than conventional methods. However, further studies are required to assess standard protocols. Over the past years, research identified some new indications for laser treatment in oral surgery and implant dentistry. Moreover, well-known laser applications were defined as state of the art. Nevertheless, further studies are required for laser treatment in oral surgery and implant dentistry.

  19. Joint state and parameter estimation for a class of cascade systems: Application to a hemodynamic model

    KAUST Repository

    Zayane, Chadia

    2014-06-01

    In this paper, we address a special case of state and parameter estimation, where the system can be put on a cascade form allowing to estimate the state components and the set of unknown parameters separately. Inspired by the nonlinear Balloon hemodynamic model for functional Magnetic Resonance Imaging problem, we propose a hierarchical approach. The system is divided into two subsystems in cascade. The state and input are first estimated from a noisy measured signal using an adaptive observer. The obtained input is then used to estimate the parameters of a linear system using the modulating functions method. Some numerical results are presented to illustrate the efficiency of the proposed method.

  20. Laser ignition application in a space experiment

    Science.gov (United States)

    Liou, Larry C.; Culley, Dennis E.

    1993-01-01

    A laser ignition system is proposed for the Combustion Experiment Module on an orbiting spacecraft. The results of a design study are given using the scheduled 'Flame Ball Experiment' as the design guidelines. Three laser ignition mechanisms and wavelengths are evaluated. A prototype laser is chosen and its specifications are given, followed by consideration of the beam optical arrangement, the ignition power requirement, the laser ignition system weight, size, reliability, and laser cooling and power consumption. Electromagnetic interference to the onboard electronics caused by the laser ignition process is discussed. Finally, ground tests are suggested.

  1. Active standoff detection of CH4 and N2O leaks using hard-target backscattered light using an open-path quantum cascade laser sensor

    Science.gov (United States)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-05-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they contribute to the global increase of greenhouse gas concentrations. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents standoff detection of CH4 and N2O leaks using a quantum cascade laser open-path system that retrieves path-averaged concentrations by collecting the backscattered light from a remote hard target. It is a true standoff system and differs from other open-path systems that are deployed as point samplers or long-path transmission systems that use retroreflectors. The measured absorption spectra are obtained using a thermal intra-pulse frequency chirped DFB quantum cascade laser at ~7.7 µm wavelength range with ~200 ns pulse width. Making fast time resolved observations, the system simultaneously realizes high spectral resolution and range to the target, resulting in path-averaged concentration retrieval. The system performs measurements at high speed ~15 Hz and sufficient range (up to 45 m, ~148 feet) achieving an uncertainty of 3.1 % and normalized sensitivity of 3.3 ppm m Hz-1/2 for N2O and 9.3 % and normalized sensitivity of 30 ppm m Hz-1/2 for CH4 with a 0.31 mW average power QCL. Given these characteristics, this system is promising for mobile or multidirectional search and remote detection of gas leaks.

  2. Protein dynamics observed by tunable mid-IR quantum cascade lasers across the time range from 10 ns to 1 s

    Science.gov (United States)

    Schultz, Bernd-Joachim; Mohrmann, Hendrik; Lorenz-Fonfria, Victor A.; Heberle, Joachim

    2018-01-01

    We have developed a spectrometer based on tunable quantum cascade lasers (QCLs) for recording time-resolved absorption spectra of proteins in the mid-infrared range. We illustrate its performance by recording time-resolved difference spectra of bacteriorhodopsin in the carboxylic range (1800-1700 cm- 1) and on the CO rebinding reaction of myoglobin (1960-1840 cm- 1), at a spectral resolution of 1 cm- 1. The spectrometric setup covers the time range from 4 ns to nearly a second with a response time of 10-15 ns. Absorption changes as low as 1 × 10- 4 are detected in single-shot experiments at t > 1 μs, and of 5 × 10- 6 in kinetics obtained after averaging 100 shots. While previous time-resolved IR experiments have mostly been conducted on hydrated films of proteins, we demonstrate here that the brilliance of tunable quantum cascade lasers is superior to perform ns time-resolved experiments even in aqueous solution (H2O).

  3. Medical Applications of Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  4. Novel 300-watt single-emitter laser diodes for laser initiation applications

    Science.gov (United States)

    Hand, Carter F.

    2010-08-01

    Laser initiation of the various explosive materials requires a wide variety of energy densities. With funding from DARPA, Alfalight has developed a Surface-Emitting Distributed Feedback (SE-DFB) lasers. The technology allows a single laser diode to replace many of today's more complex solid state lasers in LIO applications. The highest-recorded continuous output power from a single emitter - 73 watts - is detailed along with peak pulsed powers exceeding 300 watts. Other beneficial properties such as wafer-level processing, surface output coupling and on-chip beam-shaping are among the attributes of this type of laser.

  5. Declarative specifications of complex transactions, with an application to cascading deletes

    NARCIS (Netherlands)

    de Brock, E.O.; Saake, G.; Schwarz, K.; Türker, C.

    2000-01-01

    While specifications of queries usually are of a declarative nature (since the work of Codd in the early seventies), specifications of transactions mainly are of an operational and descriptive nature, Especially descriptions of complex transactions (such as cascading deletes) tend to be very

  6. Intersubband spectroscopy of ZnO/ZnMgO quantum wells grown on m-plane ZnO substrates for quantum cascade device applications (Conference Presentation)

    Science.gov (United States)

    Quach, Patrick; Jollivet, Arnaud; Isac, Nathalie; Bousseksou, Adel; Ariel, Frédéric; Tchernycheva, Maria; Julien, François H.; Montes Bajo, Miguel; Tamayo-Arriola, Julen; Hierro, Adrián.; Le Biavan, Nolwenn; Hugues, Maxime; Chauveau, Jean-Michel

    2017-03-01

    Quantum cascade (QC) lasers opens new prospects for powerful sources operating at THz frequencies. Up to now the best THz QC lasers are based on intersubband emission in GaAs/AlGaAs quantum well (QW) heterostructures. The maximum operating temperature is 200 K, which is too low for wide-spread applications. This is due to the rather low LO-phonon energy (36 meV) of GaAs-based materials. Indeed, thermal activation allows non-radiative path through electron-phonon interaction which destroys the population inversion. Wide band gap materials such as ZnO have been predicted to provide much higher operating temperatures because of the high value of their LO-phonon energy. However, despite some observations of intersubband absorption in c-plane ZnO/ZnMgO quantum wells, little is known on the fundamental parameters such as the conduction band offset in such heterostructures. In addition the internal field inherent to c-plane grown heterostuctures is an handicap for the design of QC lasers and detectors. In this talk, we will review a systematic investigation of ZnO/ZnMgO QW heterostructures with various Mg content and QW thicknesses grown by plasma molecular beam epitaxy on low-defect m-plane ZnO substrates. We will show that most samples exhibit TM-polarized intersubband absorption at room temperature linked either to bound-to-quasi bound inter-miniband absorption or to bound-to bound intersubband absorption depending on the Mg content of the barrier material. This systematic study allows for the first time to estimate the conduction band offset of ZnO/ZnMgO heterostructures, opening prospects for the design of QC devices operating at THz frequencies. This was supported by the European Union's Horizon 2020 research and innovation programme under grant agreement #665107.

  7. High-power lasers for directed-energy applications.

    Science.gov (United States)

    Sprangle, Phillip; Hafizi, Bahman; Ting, Antonio; Fischer, Richard

    2015-11-01

    In this article, we review and discuss the research programs at the Naval Research Laboratory (NRL) on high-power lasers for directed-energy (DE) applications in the atmosphere. Physical processes affecting propagation include absorption/scattering, turbulence, and thermal blooming. The power levels needed for DE applications require combining a number of lasers. In atmospheric turbulence, there is a maximum intensity that can be placed on a target that is independent of the initial beam spot size and laser beam quality. By combining a number of kW-class fiber lasers, scientists at the NRL have successfully demonstrated high-power laser propagation in a turbulent atmosphere and wireless recharging. In the NRL experiments, four incoherently combined fiber lasers having a total power of 5 kW were propagated to a target 3.2 km away. These successful high-power experiments in a realistic atmosphere formed the basis of the Navy's Laser Weapon System. We compare the propagation characteristics of coherently and incoherently combined beams without adaptive optics. There is little difference in the energy on target between coherently and incoherently combined laser beams for multi-km propagation ranges and moderate to high levels of turbulence. Unlike incoherent combining, coherent combining places severe constraints on the individual lasers. These include the requirement of narrow power spectral linewidths in order to have long coherence times as well as polarization alignment of all the lasers. These requirements are extremely difficult for high-power lasers.

  8. Applications of the femtosecond laser in corneal refractive surgery.

    Science.gov (United States)

    Kim, Peter; Sutton, Gerard L; Rootman, David S

    2011-07-01

    The femtosecond laser has become a rapidly and widely adopted technology for surgeons performing refractive surgery. With the advances in femtosecond lasers, clinical outcomes and safety with their use have improved. The purpose of this review is to outline the current surgical applications of the femtosecond laser in corneal refractive surgery. Many surgeons have adopted femtosecond technology for the creation of the laser in-situ keratomileusis flap secondary to its improved safety, precision and reproducibility. Other applications include astigmatic keratotomy, channel creation for the insertion of intrastromal corneal ring segments, femtosecond lenticule extraction, facilitating the insertion of corneal inlays as well as in intrastromal presbyopia correction (IntraCOR). Further novel applications continue to be developed. This review outlines the recent advances and applications of the femtosecond laser in corneal refractive surgery.

  9. Pulsed laser ablation of solids basics, theory and applications

    CERN Document Server

    Stafe, Mihai; Puscas, Niculae N

    2014-01-01

    The book introduces ‘the state of the art' of pulsed laser ablation and its applications. It is based on recent theoretical and experimental studies. The book reaches from the basics to advanced topics of pulsed laser ablation. Theoretical and experimental fundamental phenomena involved in pulsed laser ablation are discussed with respect to material properties, laser wavelength, fluence and intensity regime of the light absorbed linearly or non-linearly in the target material. The energy absorbed by the electrons leads to atom/molecule excitation, ionization and/or direct chemical bond breaking and is also transferred to the lattice leading to material heating and phase transitions. Experimental  non-invasive optical methods for analyzing these phenomena in real time are described. Theoretical models for pulsed laser ablation and phase transitions induced by laser beams and laser-vapour/plasma interaction during the plume expansion above the target are also presented. Calculations of the ablation speed and...

  10. Micro-scanning mirrors for high-power laser applications in laser surgery

    Science.gov (United States)

    Sandner, Thilo; Kimme, Simon; Grasshoff, Thomas; Todt, Ulrich; Graf, Alexander; Tulea, Cristian; Lenenbach, Achim; Schenk, Harald

    2014-03-01

    We present two novel micro scanning mirrors with large aperture and HR dielectric coatings suitable for high power laser applications in a miniaturized laser-surgical instrument for neurosurgery to cut skull tissue. An electrostatic driven 2D-raster scanning mirror with 5x7.1mm aperture is used for dynamic steering of a ps-laser beam of the laser cutting process. A second magnetic 2D-beam steering mirror enables a static beam correction of a hand guided laser instrument. Optimizations of a magnetic gimbal micro mirror with 6 mm x 8 mm mirror plate are presented; here static deflections of 3° were reached. Both MEMS devices were successfully tested with a high power ps-laser at 532nm up to 20W average laser power.

  11. Characteristics and Applications of Spatiotemporally Focused Femtosecond Laser Pulses

    Directory of Open Access Journals (Sweden)

    Chenrui Jing

    2016-12-01

    Full Text Available Simultaneous spatial and temporal focusing (SSTF of femtosecond laser pulses gives rise to strong suppression of nonlinear self-focusing during the propagation of the femtosecond laser beam. In this paper, we begin with an introduction of the principle of SSTF, followed by a review of our recent experimental results on the characterization and application of the spatiotemporally focused pulses for femtosecond laser micromachining. Finally, we summarize all of the results and give a future perspective of this technique.

  12. Development of Laser Application Technology for Stable Isotope Production

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Do Young; Ko, Kwang Hoon; Kwon, Duck Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] (and others)

    2007-04-15

    Tl-203 is used as a source material to produce Tl-201 radioisotope which is produced in a cyclotron by irradiating the enriched Tl-203 target. Tl-201 is a radiopharmaceutical for SPECT (single photon emission computerized tomography) to diagnose heart diseases and tumors. This Project aim to develop laser application technology to product stable isotopes such as Tl-203, Yb-168, and Yb-176. For this, photoion extraction device, atomic beam generator, dye lasers, and high power IR lasers are developed.

  13. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. [Texas Univ., Houston, TX (United States). Cancer Center; Welch, A.J. [Texas Univ., Austin, TX (United States); Motamedi, M. [Texas Univ., Galveston, TX (United States). Medical Branch; Rastegar, S. [Texas A and M Univ., College Station, TX (United States); Tittel, F. [Rice Univ., Houston, TX (United States); Esterowitz, L. [Naval Research Lab., Washington, DC (United States)

    1993-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the collaborating engineering enters at Rice University, UT-Austin, Texas A&M Univ. In addition, this collective is collaborating with the naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  14. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. (Texas Univ., Houston, TX (United States). Cancer Center); Welch, A.J. (Texas Univ., Austin, TX (United States)); Motamedi, M. (Texas Univ., Galveston, TX (United States). Medical Branch); Rastegar, S. (Texas A and M Univ., College Station, TX (United States)); Tittel, F. (Rice Univ., Houston, TX (United States)); Esterowitz, L. (Naval Research Lab., Washington, DC (United States))

    1992-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the colloborating engineering centers at Rice University, UT-Austin, and Texas A M Univ. In addition, this collective is collaborating with the Naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  15. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. [Texas Univ., Houston, TX (United States). Cancer Center; Welch, A.J. [Texas Univ., Austin, TX (United States); Motamedi, M. [Texas Univ., Galveston, TX (United States). Medical Branch; Rastegar, S. [Texas A and M Univ., College Station, TX (United States); Tittel, F. [Rice Univ., Houston, TX (United States); Esterowitz, L. [Naval Research Lab., Washington, DC (United States)

    1992-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the colloborating engineering centers at Rice University, UT-Austin, and Texas A&M Univ. In addition, this collective is collaborating with the Naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  16. Dual-Electrical-Port Control of Cascaded Brushless Doubly-Fed Induction Drive for EV/HEV Applications

    DEFF Research Database (Denmark)

    Han, Peng; Cheng, Ming; Chen, Zhe

    2016-01-01

    This paper presents a dual-electrical-port control scheme of cascaded brushless doubly-fed induction machine (CBDFIM) for EV/HEV applications aiming at achieving doubled constant torque and constant power regions compared to its singly-fed counterpart with the same equivalent pole pair number....... The proposed control method enables the synchronous control of both current inputs of power winding and control winding and as a consequence, not only the control complexity, but also slip frequency and core loss are significantly reduced in comparison with the single-electrical-port control scheme. Computer...

  17. Cascaded Kerr photon-blockade soruces and applications in quantum key distribution.

    Science.gov (United States)

    Li, Ao; Zhou, Yiheng; Wang, Xiang-Bin

    2017-08-04

    To raise the repetition rate, a single-photon source based on Kerr quantum blockade in a cascaded quantum system is studied. Using the quantum trajectory method, we calculate and simulate the photon number distributions out of a two-cavity system. A high quality single-photon source can be achieved through optimizing parameters. The designed photon source is further applied to the decoy state quantum key distribution (QKD). With and without statistical fluctuation, the key rate can be both raised drastically.

  18. Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

    Science.gov (United States)

    Reinl, S.

    Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

  19. Ophthalmic applications of ultrashort pulsed lasers

    Science.gov (United States)

    Juhasz, Tibor; Spooner, Greg; Sacks, Zachary S.; Suarez, Carlos G.; Raksi, Ferenc; Zadoyan, Ruben; Sarayba, Melvin; Kurtz, Ronald M.

    2004-06-01

    Ultrashort laser pulses can be used to create high precision incision in transparent and translucent tissue with minimal damage to adjacent tissue. These performance characteristics meet important surgical requirements in ophthalmology, where femtosecond laser flap creation is becoming a widely used refractive surgery procedure. We summarize clinical findings with femtosecond laser flaps as well as early experiments with other corneal surgical procedures such as corneal transplants. We also review laser-tissue interaction studies in the human sclera and their consequences for the treatment of glaucoma.

  20. Mode-Locked Laser Arrays for WDM Applications

    Science.gov (United States)

    Forouhar, S.

    1997-01-01

    Colliding pulse mode-locked laser arrays are being developed at 20 GHz for WDM applications. Arrays with 5 wavelengths in the EDFA gain bandwidth have already been demonstrated, with the final goal being a packaged, 10 wavelength mode-locked laser array.

  1. Characteristics of Overvoltage Protection with Cascade Application of Surge Protective Devices in Low-Voltage AC Power Circuits

    Directory of Open Access Journals (Sweden)

    RADULOVIC, V.

    2015-08-01

    Full Text Available Surge Protective Devices (SPDs are widely used for protection of the equipment in low-voltage AC power circuits against wide variety of surges. Cascade application of SPDs starting at the service entrance of a building and downstream toward near sensitive equipment is intended to ensure optimal energy distribution among installed SPDs, as well as proper equipment protection against surges. Characteristics of overvoltage protection with two-stage application of SPDs have been analyzed in the paper through performed measurements, followed by simulations and numerical modeling using the ATP/EMTP and MATLAB Simulink. Parametric analysis of the protection's characteristics in wide range of influencing factors has been performed in order to define a set of applicable solutions for proper selection and performance of SPDs.

  2. CO concentration and temperature sensor for combustion gases using quantum-cascade laser absorption near 4.7 μm

    KAUST Repository

    Ren, Wei

    2012-05-25

    A sensor for sensitive in situ measurements of carbon monoxide and temperature in combustion gases has been developed using absorption transitions in the (v′ = 1 ← v″ = 0) and (v′ = 2 ← v″ = 1) fundamental bands of CO. Recent availability of mid-infrared quantum-cascade (QC) lasers provides convenient access to the CO fundamental band near 4.7 μm, having approximately 104 and 102 times stronger absorption line-strengths compared to the overtone bands near 1.55 μm and 2.3 μm used previously to sense CO in combustion gases. Spectroscopic parameters of the selected transitions were determined via laboratory measurements in a shock tube over the 1100-2000 K range and also at room temperature. A single-laser absorption sensor was developed for accurate CO measurements in shock-heated gases by scanning the line pair v″ = 0, R(12) and v″ = 1, R(21) at 2.5 kHz. To capture the rapidly varying CO time-histories in chemical reactions, two different QC lasers were then used to probe the line-center absorbance of transitions v″ = 0, P(20) and v″ = 1, R(21) with a bandwidth of 1 MHz using fixed-wavelength direct absorption. The sensor was applied in successful shock tube measurements of temperature and CO time-histories during the pyrolysis and oxidation of methyl formate, illustrating the capability of this sensor for chemical kinetic studies. © 2012 Springer-Verlag.

  3. Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    Science.gov (United States)

    Yi, Hongming; Maamary, Rabih; Gao, Xiaoming; Sigrist, Markus W.; Fertein, Eric; Chen, Weidong

    2015-03-01

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm-1 was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ˜40 mm3) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by direct absorption spectroscopy involving a ˜109.5 m multipass cell and a distributed feedback QCL. A minimum detection limit (MDL) of 66 ppbv (1 σ) HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6 × 10-8 cm-1 W/Hz1/2. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding 1σ minimum detected absorption coefficient is ˜1.1 × 10-7 cm-1 (MDL ˜ 3 ppbv) in 1 s and ˜1.1 × 10-8 cm-1 (MDL ˜ 330 pptv) in 150 s, respectively, with 1 W laser power.

  4. Laser Science and its Applications in Prosthetic Rehabilitation

    Science.gov (United States)

    Gounder, Revathy; Gounder, Srinivasan

    2016-01-01

    The minimal invasive nature of lasers, with quick tissue response and healing has made them a very attractive technology in various fields of dentistry which serves as a tool to create a better result than ever before. The rapid development of lasers and their wavelengths with variety of applications on soft and hard tissues may continue to have major impact on the scope and practice in prosthetic dentistry. The purpose of this article is to make every clinician familiar with the fundamentals of lasers and different laser systems to incorporate into their clinical practices. PMID:28491254

  5. Measurement of electron density and electron temperature of a cascaded arc plasma using laser Thomson scattering compared to an optical emission spectroscopic approach

    Science.gov (United States)

    Yong, WANG; Cong, LI; Jielin, SHI; Xingwei, WU; Hongbin, DING

    2017-11-01

    As advanced linear plasma sources, cascaded arc plasma devices have been used to generate steady plasma with high electron density, high particle flux and low electron temperature. To measure electron density and electron temperature of the plasma device accurately, a laser Thomson scattering (LTS) system, which is generally recognized as the most precise plasma diagnostic method, has been established in our lab in Dalian University of Technology. The electron density has been measured successfully in the region of 4.5 × 1019 m-3 to 7.1 × 1020 m-3 and electron temperature in the region of 0.18 eV to 0.58 eV. For comparison, an optical emission spectroscopy (OES) system was established as well. The results showed that the electron excitation temperature (configuration temperature) measured by OES is significantly higher than the electron temperature (kinetic electron temperature) measured by LTS by up to 40% in the given discharge conditions. The results indicate that the cascaded arc plasma is recombining plasma and it is not in local thermodynamic equilibrium (LTE). This leads to significant error using OES when characterizing the electron temperature in a non-LTE plasma.

  6. Advanced laser diodes for sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    VAWTER,GREGORY A.; MAR,ALAN; CHOW,WENG W.; ALLERMAN,ANDREW A.

    2000-01-01

    The authors have developed diode lasers for short pulse duration and high peak pulse power in the 0.01--100.0 m pulsewidth regime. A primary goal of the program was producing up to 10 W while maintaining good far-field beam quality and ease of manufacturability for low cost. High peak power, 17 W, picosecond pulses have been achieved by gain switching of flared geometry waveguide lasers and amplifiers. Such high powers area world record for this type of diode laser. The light emission pattern from diode lasers is of critical importance for sensing systems such as range finding and chemical detection. They have developed a new integrated optical beam transformer producing rib-waveguide diode lasers with a symmetric, low divergence, output beam and increased upper power limits for irreversible facet damage.

  7. Laser physics and a review of laser applications in dentistry for children.

    Science.gov (United States)

    Martens, L C

    2011-04-01

    The aim of this introduction to this special laser issue is to describe some basic laser physics and to delineate the potential of laser-assisted dentistry in children. A brief review of the available laser literature was performed within the scope of paediatric dentistry. Attention was paid to soft tissue surgery, caries prevention and diagnosis, cavity preparation, comfort of the patient, effect on bacteria, long term pulpal vitality, endodontics in primary teeth, dental traumatology and low level laser therapy. Although there is a lack of sufficient evidence taking into account the highest standards for evidence-based dentistry, it is clear that laser application in a number of different aetiologies for soft tissue surgery in children has proven to be successful. Lasers provide a refined diagnosis of caries combined with the appropriate preventive adhesive dentistry after cavity preparation. This will further lead to a new wave of micro-dentistry based on 'filling without drilling'. It has become clear from a review of the literature that specific laser applications in paediatric dentistry have gained increasing importance. It can be concluded that children should be considered as amongst the first patients for receiving laser-assisted dentistry.

  8. Alignment of CH{sub 3}F in para-H{sub 2} crystal studied by IR quantum cascade laser polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto [Department of Physics, Tokyo Institute of Technology, Ohokayama 2-12-1, Tokyo 152-8551 (Japan)

    2016-05-14

    In order to investigate the alignment of CH{sub 3}F in para-H{sub 2} crystals, high resolution polarization spectroscopy of the ν{sub 3} vibrational band is studied using a quantum cascade laser at 1040 cm{sup −1}. It is found that the main and satellite series of peaks in the ν{sub 3} vibrational band of CH{sub 3}F have the same polarization dependence. This result supports the previously proposed cluster model with ortho-H{sub 2} in first and second nearest neighbor sites. The observed polarization dependence function is well described by a simple six-axis void model in which CH{sub 3}F is not aligned along the c-axis of the crystal but tilted to 64.9(3)° from it.

  9. Measurements of linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene in the ν4+ν5 combination band using a cw quantum cascade laser

    KAUST Repository

    Sajid, Muhammad Bilal

    2014-11-01

    Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 combination band and other vibrational bands of acetylene. © 2014 Elsevier Ltd.

  10. Electrical tuning of the oscillator strength in type II InAs/GaInSb quantum wells for active region of passively mode-locked interband cascade lasers

    Science.gov (United States)

    Dyksik, Mateusz; Motyka, Marcin; Kurka, Marcin; Ryczko, Krzysztof; Misiewicz, Jan; Schade, Anne; Kamp, Martin; Höfling, Sven; Sęk, Grzegorz

    2017-11-01

    Two designs of active region for an interband cascade laser, based on double or triple GaInSb/InAs type II quantum wells (QWs), were compared with respect to passive mode-locked operation in the mid-infrared range around 4 µm. The layer structure and electron and hole wavefunctions under external electric field were engineered to allow controlling the optical transition oscillator strength and the resulting lifetimes. As a result, the investigated structures can mimic absorber-like and gain-like sections of a mode-locked device when properly polarized with opposite bias. A significantly larger oscillator strength tuning range for triple QWs was experimentally verified by Fourier-transform photoreflectance.

  11. Self-consistent electro-opto-thermal model of quantum cascade lasers with coupled electron and phonon interactions far from equilibrium

    Science.gov (United States)

    Yousefvand, Hossein Reza

    2017-12-01

    A self-consistent model of quantum cascade lasers (QCLs) is presented here for the study of the QCL's behavior in the far from equilibrium conditions. The approach is developed by employing a number of physics-based models such as the carrier and photon rate equations, the energy balance equation, the heat transfer equation and a simplified rate equation for the creation and annihilation of nonequilibrium optical phonons. The temperature dependency of the relevant physical effects such as stimulated gain cross section, longitudinal optical (LO) phonons and hot-phonon generation rates are included in the model. Using the presented model, the static and transient device characteristics are calculated and analyzed for a wide range of heat sink temperatures. Besides the output characteristics, this model also provides a way to study the hot-phonon dynamics in the device, and to explore the electron temperature and thermal roll-over in the QCLs.

  12. Non-equilibrium Green's function calculation of AlGaAs-well-based and GaSb-based terahertz quantum cascade laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, H., E-mail: yasuda@nict.go.jp; Hosako, I. [National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan)

    2015-03-16

    We investigate the performance of terahertz quantum cascade lasers (THz-QCLs) based on Al{sub x}Ga{sub 1−x}As/Al{sub y}Ga{sub 1−y}As and GaSb/AlGaSb material systems to realize higher-temperature operation. Calculations with the non-equilibrium Green's function method reveal that the AlGaAs-well-based THz-QCLs do not show improved performance, mainly because of alloy scattering in the ternary compound semiconductor. The GaSb-based THz-QCLs offer clear advantages over GaAs-based THz-QCLs. Weaker longitudinal optical phonon–electron interaction in GaSb produces higher peaks in the spectral functions of the lasing levels, which enables more electrons to be accumulated in the upper lasing level.

  13. Measurements of linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene in the ν4+ν5 combination band using a cw quantum cascade laser

    Science.gov (United States)

    Sajid, Muhammad Bilal; Es-sebbar, Et-touhami; Farooq, Aamir

    2014-11-01

    Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296 K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683 K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310 cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 combination band and other vibrational bands of acetylene.

  14. Nine orders of magnitude dynamic range: picomolar to millimolar concentration measurement in capillary electrophoresis with laser induced fluorescence detection employing cascaded avalanche photodiode photon counters.

    Science.gov (United States)

    Dada, Oluwatosin O; Essaka, David C; Hindsgaul, Ole; Palcic, Monica M; Prendergast, Jillian; Schnaar, Ronald L; Dovichi, Norman J

    2011-04-01

    The dynamic range of capillary electrophoresis analysis is ultimately limited by molecular shot noise at low concentrations and by concentration-induced band broadening at high concentrations. We report a system that approaches these fundamental limits. A laser-induced fluorescence detector is reported that employs a cascade of four fiber-optic beam splitters connected in series to generate a primary signal and four attenuated signals, each monitored by a single-photon counting avalanche photodiode. Appropriate scaling of the signals from the five photodiodes produces a linear optical calibration curve for 5-carboxyl-tetramethylrhodamine from the concentration detection limit of 1 pM to the upper limit of 1 mM. Mass detection limits are 120 yoctomoles (70 molecules) injected into the instrument. The very-wide dynamic range instrument was used to study the metabolic products of the fluorescently labeled glycosphingolipid tetramethylrhodamine labeled GM1 (GM1-TMR) produced by single cells isolated from the rat cerebellum.

  15. Phenomenological scattering-rate model for the simulation of the current density and emission power in mid-infrared quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kurlov, S. S. [Department of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin (Germany); Institute of Semiconductor Physics, National Academy of Sciences, pr. Nauki 45, Kiev-03028 (Ukraine); Flores, Y. V.; Elagin, M.; Semtsiv, M. P.; Masselink, W. T. [Department of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin (Germany); Schrottke, L.; Grahn, H. T. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Tarasov, G. G. [Institute of Semiconductor Physics, National Academy of Sciences, pr. Nauki 45, Kiev-03028 (Ukraine)

    2016-04-07

    A phenomenological scattering-rate model introduced for terahertz quantum cascade lasers (QCLs) [Schrottke et al., Semicond. Sci. Technol. 25, 045025 (2010)] is extended to mid-infrared (MIR) QCLs by including the energy dependence of the intersubband scattering rates for energies higher than the longitudinal optical phonon energy. This energy dependence is obtained from a phenomenological fit of the intersubband scattering rates based on published lifetimes of a number of MIR QCLs. In our approach, the total intersubband scattering rate is written as the product of the exchange integral for the squared moduli of the envelope functions and a phenomenological factor that depends only on the transition energy. Using the model to calculate scattering rates and imposing periodical boundary conditions on the current density, we find a good agreement with low-temperature data for current-voltage, power-current, and energy-photon flux characteristics for a QCL emitting at 5.2 μm.

  16. Experimental and modeling study of off-beam quartz-enhanced photoacoustic detection of nitrogen monoxide (NO) using a quantum cascade laser

    Science.gov (United States)

    Shi, Chao; Li, Zhili; Ren, Wei

    2016-11-01

    This article presents the experimental and modeling study of quartz-enhanced photoacoustic detection of nitrogen monoxide (NO) using the off-beam configuration and a distributed-feedback (DFB) quantum cascade laser (QCL) at 5.26 μm as the excitation source. Trace gas monitoring of NO is one of the important subjects for both environmental protection and human health monitoring. Quartz-enhanced photoacoustic spectroscopy (QEPAS) with on-beam configuration is mostly adopted for gas detection. In comparison, the off-beam approach has not only comparative detection sensitivity but also significant advantage of simpler installation and optical alignment. We optimized the sensor performance by adjusting the horizontal and vertical distances between the micro-resonator (mR) and the QTF prongs. Pressure and humidity are two important factors affecting the photoacoustic signal. The effects of both parameters on the NO concentration determination were investigated.

  17. Femtosecond lasers in ophthalmology: clinical applications in anterior segment surgery

    Science.gov (United States)

    Juhasz, Tibor; Nagy, Zoltan; Sarayba, Melvin; Kurtz, Ronald M.

    2010-02-01

    The human eye is a favored target for laser surgery due to its accessibility via the optically transparent ocular tissue. Femtosecond lasers with confined tissue effects and minimized collateral tissue damage are primary candidates for high precision intraocular surgery. The advent of compact diode-pumped femtosecond lasers, coupled with computer controlled beam delivery devices, enabled the development of high precision femtosecond laser for ophthalmic surgery. In this article, anterior segment femtosecond laser applications currently in clinical practice and investigation are reviewed. Corneal procedures evolved first and remain dominant due to easy targeting referenced from a contact surface, such as applanation lenses placed on the eye. Adding a high precision imaging technique, such as optical coherence tomography (OCT), can enable accurate targeting of tissue beyond the cornea, such as the crystalline lens. Initial clinical results of femtosecond laser cataract surgery are discussed in detail in the latter portion part of the article.

  18. A multi-wavelength IR laser for space applications

    Science.gov (United States)

    Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

    2017-05-01

    We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to midinfrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 µm, 2.7 μm and 3.4 μm. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated

  19. A Multi-Wavelength IR Laser for Space Applications

    Science.gov (United States)

    Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

    2017-01-01

    We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to mid-infrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 microns, 2.7 microns and 3.4 microns. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated.

  20. Laser Processing of Materials Fundamentals, Applications and Developments

    CERN Document Server

    Schaaf, Peter

    2010-01-01

    Laser materials processing has made tremendous progress and is now at the forefront of industrial and medical applications. The book describes recent advances in smart and nanoscaled materials going well beyond the traditional cutting and welding applications. As no analytical methods are described the examples are really going into the details of what nowadways is possible by employing lasers for sophisticated materials processing giving rise to achievements not possible by conventional materials processing.

  1. Potential applications of Erbium:YAG laser in periodontics.

    Science.gov (United States)

    Ishikawa, Isao; Aoki, Akira; Takasaki, Aristeo Atsushi

    2004-08-01

    Since lasers were introduced for the treatment of oral diseases, there has been considerable advancement in technology. As a result, numerous laser systems are currently available for oral use. Neodymium:Yttrium-Aluminum:Garnet (Nd:YAG), carbon dioxide (CO(2)) laser and the semiconductor Diode lasers have already been approved by the US Food and Drug Administration for soft tissue treatment in oral cavity. The Erbium:YAG (Er:YAG) laser was approved in 1997 for hard tissue treatment in dentistry and recent studies have reported positive results. This suggests that the Er:YAG laser system is a promising apparatus, which will be able to revolutionize and improve dental practice, in particular periodontal treatment. In this mini-review, we would like to describe the positive characteristics of the Er:YAG laser which indicate its potential as a new treatment modality in periodontics. Recent findings are summarized briefly to evaluate the potential of the Er:YAG laser for clinical application in periodontics. The Er:YAG laser possesses suitable characteristics for oral soft and hard tissue ablation. Recently, it has been applied for effective elimination of granulation tissue, gingival melanin pigmentation and gingival discoloration. Contouring and cutting of bone with minimal damage and even or faster healing can also be performed with this laser. In addition, irradiation with the Er:YAG laser has a bactericidal effect with reduction of lipopolysaccharide, high ability of plaque and calculus removal, with the effect limited to a very thin layer of the surface and is effective for implant maintenance. The Er:YAG laser seems to be an effective tool for periodontal therapy, however, further clinical and basic investigations are required to confirm its clinical application. Copyright Blackwell Munksgaard, 2004

  2. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji

    2017-01-01

    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  3. Application of advanced laser diagnostics to hypersonic wind tunnels and combustion systems.

    Energy Technology Data Exchange (ETDEWEB)

    North, Simon W. (Texas A& M University, College Station, TX); Hsu, Andrea G. (Texas A& M University, College Station, TX); Frank, Jonathan H.

    2009-09-01

    This LDRD was a Sandia Fellowship that supported Andrea Hsu's PhD research at Texas A&M University and her work as a visitor at Sandia's Combustion Research Facility. The research project at Texas A&M University is concerned with the experimental characterization of hypersonic (Mach>5) flowfields using experimental diagnostics. This effort is part of a Multidisciplinary University Research Initiative (MURI) and is a collaboration between the Chemistry and Aerospace Engineering departments. Hypersonic flight conditions often lead to a non-thermochemical equilibrium (NTE) state of air, where the timescale of reaching a single (equilibrium) Boltzmann temperature is much longer than the timescale of the flow. Certain molecular modes, such as vibrational modes, may be much more excited than the translational or rotational modes of the molecule, leading to thermal-nonequilibrium. A nontrivial amount of energy is therefore contained within the vibrational mode, and this energy cascades into the flow as thermal energy, affecting flow properties through vibrational-vibrational (V-V) and vibrational-translational (V-T) energy exchanges between the flow species. The research is a fundamental experimental study of these NTE systems and involves the application of advanced laser and optical diagnostics towards hypersonic flowfields. The research is broken down into two main categories: the application and adaptation of existing laser and optical techniques towards characterization of NTE, and the development of new molecular tagging velocimetry techniques which have been demonstrated in an underexpanded jet flowfield, but may be extended towards a variety of flowfields. In addition, Andrea's work at Sandia National Labs involved the application of advanced laser diagnostics to flames and turbulent non-reacting jets. These studies included quench-free planar laser-induced fluorescence measurements of nitric oxide (NO) and mixture fraction measurements via Rayleigh

  4. Infrared semiconductor laser based trace gas sensor technologies: recent advances and applications

    Science.gov (United States)

    Tittel, Frank K.; Curl, Robert F.; Dong, Lei; Lewicki, Rafal

    2011-05-01

    Recent advances in the development of trace gas sensors based on the use of quantum cascade lasers (QCLs) for the sensitive, selective detection, quantification and monitoring of small molecular gas species with resolved spectroscopic features will be described. High detection sensitivity at ppbv and sub-ppbv concentration levels require detection sensitivity, enhancement schemes such as multipass absorption cells, cavity enhanced absorption techniques, or quartz enhanced photo-acoustic absorption spectroscopy (QEPAS). These three spectroscopic methods can achieve minimum detectable absorption losses in the range from 10-8 to 10-11 cm-1/√Hz. Two recent examples of real world applications of field deployable PAS and QEPAS based gas sensors will be reported, namely the monitoring of ammonia concentrations in exhaled human breath and major urban environments.

  5. Diode laser welding in microvascular applications

    Science.gov (United States)

    Reali, Umberto M.; Gelli, Riccardo; Giannotti, Vanni; D'Anna, M.; Pini, Roberto; Toncelli, F.; Vanni, U.

    1994-12-01

    In this work we report our experiences on diode laser-assisted end-to-end microvascular anastomosis performed on femoral arteries and veins of rats and rabbits at very low laser power (30 - 40 mW). In the course of our trials we approached laser anastomosis with a reduced number of permanent stays to decrease foreign body reaction. Recently we demonstrated the possibility to perform anastomosis without supporting stays. Significant improvements in comparison with traditional procedures were also furnished by histology examination, which showed a better healing process in LAMA cases.

  6. Magnetic Dipole Inflation with Cascaded ARC and Applications to Mini-Magnetospheric Plasma Propulsion

    Science.gov (United States)

    Giersch, L.; Winglee, R.; Slough, J.; Ziemba, T.; Euripides, P.

    2003-01-01

    Mini-Magnetospheric Plasma Propulsion (M2P2) seeks to create a plasma-inflated magnetic bubble capable of intercepting significant thrust from the solar wind for the purposes of high speed, high efficiency spacecraft propulsion. Previous laboratory experiments into the M2P2 concept have primarily used helicon plasma sources to inflate the dipole magnetic field. The work presented here uses an alternative plasma source, the cascaded arc, in a geometry similar to that used in previous helicon experiments. Time resolved measurements of the equatorial plasma density have been conducted and the results are discussed. The equatorial plasma density transitions from an initially asymmetric configuration early in the shot to a quasisymmetric configuration during plasma production, and then returns to an asymmetric configuration when the source is shut off. The exact reasons for these changes in configuration are unknown, but convection of the loaded flux tube is suspected. The diffusion time was found to be an order of magnitude longer than the Bohm diffusion time for the period of time after the plasma source was shut off. The data collected indicate the plasma has an electron temperature of approximately 11 eV, an order of magnitude hotter than plasmas generated by cascaded arcs operating under different conditions. In addition, indirect evidence suggests that the plasma has a beta of order unity in the source region.

  7. Dual-Electrical-Port Control of Cascaded Doubly-Fed Induction Machine for EV/HEV Applications

    DEFF Research Database (Denmark)

    Han, Peng; Cheng, Ming; Chen, Zhe

    2017-01-01

    This paper presents a dual-electrical-port control scheme for four-quadrant operation of cascaded doubly-fed induction machine (CDFIM), which has conventionally been used as a variable-speed drive or variable-speed constant-frequency generator for limited-speed-range applications. The proposed......-electrical-port control scheme. It is for the first time revealed that the CDFIM drive that indirectly couples PW and CW through induction behavior can be readily controlled like a conventional induction motor to achieve the highest torque density. The torque density-speed region of the CDFIM falls within...... that of the power machine in singly-fed operation mode, and only a half of that of the power machine in doubly-fed operation mode, which shows the urgent need for torque density enhancement of brushless doubly-fed machines for electric vehicle/hybrid electric vehicle applications. Computer simulations...

  8. Development of Miniaturized Intra-Cavity DFG, Fiber-Optic, and Quantum Cascade Laser Systems in Conjunction with Integrated Electronics for Global Studies of Climate Forcing and Response using UASs as a Partner with Satellite and Adaptive Models

    Science.gov (United States)

    Witinski, M. F.; Demusz, J. N.; Rivero, M.; Tuozzolo, C.; Anderson, J. G.

    2008-12-01

    The 2007 National Research Council (NRC) report, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, delineates an array of challenges facing society as the global climate system passes through a period of unprecedented changes. The Decadal Survey goes further, recommending specific science missions that will concentrate NASA's tremendous technical resources on meeting these challenges. Central to completing these science missions will be the effective union of advancing laser, electro-optical, and computing technologies with emerging Uninhabited Aerial Systems (UAS), allowing for satellite validation and independent science missions of unprecedented duration and scientific capability, in effect linking NASA's orbital and sub-orbital programs to each other and to the objectives of society as a whole. In order to harness the power of UASs for in situ atmospheric monitoring of tracers such as CO2, N2O, and CH4 as a precursor for extending detection limits to encompass sub-ppb level species, we have developed small, lightweight, single mode laser systems with co-developed integrated electronics. The laser sources are of various types, including newly developed cavity-enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a custom-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electronic systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electronic components in

  9. Clinical application of lasers in Asians.

    Science.gov (United States)

    Chan, Henry H; Alam, Murad; Kono, Taro; Dover, Jeffery S

    2002-07-01

    Laser surgery for Asians differs from that for Caucasians in several important respects. In Asians, some conditions such as nevus of Ota are frequently seen and certain adverse reactions, especially postinflammatory hyperpigmentation, tend to be more common. This article reviews the use of different types of lasers and intense pulsed light (IPL) sources for the treatment of Asian patients. Various cutaneous conditions amenable to laser treatment, including lentigines, nevus of Ota, acquired bilateral nevus of Ota-like macules, port-wine stains, and acne scarring, are discussed. Strategies for the management of postinflammatory hyperpigmentation are offered. Appropriate selection and careful planning of the treatment can lead to excellent clinical outcome. Lasers and intense pulsed light sources are important tools for the treatment of a wide range of cutaneous conditions in Asians.

  10. Analytical methods of laser spectroscopy for biomedical applications

    Science.gov (United States)

    Martyshkin, Dmitri V.

    Different aspects of the application of laser spectroscopy in biomedical research have been considered. A growing demand for molecular sensing techniques in biomedical and environmental research has led the introduction of existing spectroscopic techniques, as well as development of new methods. The applications of laser-induced fluorescence, Raman scattering, cavity ring-down spectroscopy, and laser-induced breakdown spectroscopy for the monitoring of superoxide dismutase (SOD) and hemoglobin levels, the study of the characteristics of light-curing dental restorative materials, and the environmental monitoring of levels of toxic metal ion is presented. The development of new solid-state tunable laser sources based on color center crystals for these applications is presented as well.

  11. A new class of polarization filters for laser applications

    Science.gov (United States)

    Wang, Ligang; Hodgson, Craig; Erdogan, Turan

    2010-02-01

    We describe a unique new, high-contrast, laser-grade polarizer which also acts a high-performance bandpass filter for the desired, transmitted polarization. This thin-film based polarizer combines a polarization contrast ratio greater than 1,000,000-to-1 (extinction ratio 93%, very steep edges, and high out-of- band blocking, all in a single, high-layer-count optical coating. Compared to other polarizer technologies, it offers superior optical quality, high angle-of-incidence tolerance, and large clear apertures, making it suitable for high-performance imaging applications. And this filter exhibits excellent environmental reliability and high laser damage threshold (> 1 J/cm2). These new polarizing bandpass filters are excellent laser source clean-up filters to eliminate the undesired polarization at the laser line and light noise away from the laser wavelength, as well as detection filters to pass a laser wavelength range and block background noise. They are ideal for a wide variety of laboratory laser applications, especially those involving holographic and interferometric systems, as well as laser materials processing, polarization diversity detection in communications and rangefinding, and fluorescence polarization and second-harmonic-generation imaging.

  12. Laser production and heating of plasma for MHD application

    Science.gov (United States)

    Jalufka, N. W.

    1988-01-01

    Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO2 laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO2 laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO2 laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.

  13. A Cascading Storm-Flood-Landslide Guidance System: Development and Application in China

    Science.gov (United States)

    Zeng, Ziyue; Tang, Guoqiang; Long, Di; Ma, Meihong; Hong, Yang

    2016-04-01

    Flash floods and landslides, triggered by storms, often interact and cause cascading effects on human lives and property. Satellite remote sensing data has significant potential use in analysis of these natural hazards. As one of the regions continuously affected by severe flash floods and landslides, Yunnan Province, located in Southwest China, has a complex mountainous hydrometeorology and suffers from frequent heavy rainfalls from May through to late September. Taking Yunnan as a test-bed, this study proposed a Cascading Storm-Flood-Landslide Guidance System to progressively analysis and evaluate the risk of the multi-hazards based on multisource satellite remote sensing data. First, three standardized rainfall amounts (average daily amount in flood seasons, maximum 1h and maximum 6h amount) from the products of Topical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) were used as rainfall indicators to derive the StorM Hazard Index (SMHI). In this process, an integrated approach of the Analytic Hierarchy Process (AHP) and the Information-Entropy theory was adopted to determine the weight of each indicator. Then, land cover and vegetation cover data from the Moderate Resolution Imaging Spectroradiometer (MODIS) products, soil type from the Harmonized World Soil Database (HWSD) soil map, and slope from the Shuttle Radar Topography Mission (SRTM) data were add as semi-static geo-topographical indicators to derive the Flash Flood Hazard Index (FFHI). Furthermore, three more relevant landslide-controlling indicators, including elevation, slope angle and soil text were involved to derive the LandSlide Hazard Index (LSHI). Further inclusion of GDP, population and prevention measures as vulnerability indicators enabled to consecutively predict the risk of storm to flash flood and landslide, respectively. Consequently, the spatial patterns of the hazard indices show that the southeast of Yunnan has more possibility to encounter with storms

  14. Testing relativity again, laser, laser, laser, laser

    NARCIS (Netherlands)

    Einstein, A.

    2015-01-01

    laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser,

  15. The development of novel Ytterbium fiber lasers and their applications

    Science.gov (United States)

    Nie, Bai

    The aim of my Ph.D. research is to push the fundamental limits holding back the development of novel Yb fiber lasers with high pulse energy and short pulse duration. The purpose of developing these lasers is to use them for important applications such as multiphoton microscopy and laser-induced breakdown spectroscopy. My first project was to develop a short-pulse high-energy ultrafast fiber laser for multiphoton microscopy. To achieve high multiphoton efficiency and depth resolved tissue imaging, ultrashort pulse duration and high pulse energy are required. In order to achieve this, an all-normal dispersion cavity design was adopted. Output performances of the built lasers were investigated by varying several cavity parameters, such as pump laser power, fiber length and intra-cavity spectral filter bandwidth. It was found that the length of the fiber preceding the gain fiber is critical to the laser performance. Generally, the shorter the fiber is, the broader the output spectrum is. The more interesting parameter is the intra-cavity spectral filter bandwidth. Counter intuitively, laser cavities using narrower bandwidth spectral filters generated much broader spectra. It was also found that fiber lasers with very narrow spectral filters produced laser pulses with parabolic profile, which are referred to as self-similar pulses or similaritons. This type of pulse can avoid wave-breaking and is an optimal approach to generate pulses with high pulse energy and ultrashort pulse duration. With a 3nm intra-cavity spectral filter, output pulses with about 20 nJ pulse energy were produced and compressed to about 41 fs full-width-at-half-maximum (FWHM) pulse duration. Due to the loss in the compression device, the peak power of the compressed pulses is about 250 kW. It was the highest peak power generated from a fiber oscillator when this work was published. This laser was used for multiphoton microscopy on living tissues like Drosophila larva and fruit fly wings. Several

  16. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  17. Application of analytical target cascading method in multidisciplinary design optimization of ship conceptual design

    Directory of Open Access Journals (Sweden)

    WANG Jian

    2017-10-01

    Full Text Available [Objectives] Ship conceptual design requires the coordination of many different disciplines for comprehensive optimization, which presents a complicated system design problem affecting several fields of technology. However, the development of overall ship design is relatively slow compared with other subjects. [Methods] The decomposition and coordination strategy of ship design is presented, and the analytical target cascading (ATC method is applied to the multidisciplinary design optimization of the conceptual design phase of ships on this basis. A tank ship example covering the 5 disciplines of buoyancy and stability, rapidity, maneuverability, capacity and economy is established to illustrate the analysis process in the present study. [Results] The results demonstrate the stability, convergence and validity of the ATC method in dealing with the complex coupling effect occurring in ship conceptual design.[Conclusions] The proposed method provides an effective basis for optimization of ship conceptual design.

  18. Loophole to the universal photon spectrum in electromagnetic cascades and application to the cosmological lithium problem.

    Science.gov (United States)

    Poulin, Vivian; Serpico, Pasquale Dario

    2015-03-06

    The standard theory of electromagnetic cascades onto a photon background predicts a quasiuniversal shape for the resulting nonthermal photon spectrum. This has been applied to very disparate fields, including nonthermal big bang nucleosynthesis (BBN). However, once the energy of the injected photons falls below the pair-production threshold the spectral shape is much harder, a fact that has been overlooked in past literature. This loophole may have important phenomenological consequences, since it generically alters the BBN bounds on nonthermal relics; for instance, it allows us to reopen the possibility of purely electromagnetic solutions to the so-called "cosmological lithium problem," which were thought to be excluded by other cosmological constraints. We show this with a proof-of-principle example and a simple particle physics model, compared with previous literature.

  19. Mevalonate Cascade and Neurodevelopmental and Neurodegenerative Diseases: Future Targets for Therapeutic Application.

    Science.gov (United States)

    Jiao, Xiaodan; Ashtari, Niloufar; Rahimi-Balaei, Maryam; Chen, Qi Min; Badbezanchi, Ilnaz; Shojaei, Shahla; Marzban, Adel; Mirzaei, Nima; Chung, Seunghyuk; Guan, Teng; Li, Jiasi; Vriend, Jerry; Mehr, Shahram Ejtemaei; Kong, Jiming; Marzban, Hassan

    2017-01-01

    The mevalonate cascade is a key metabolic pathway that regulates a variety of cellular functions and is thereby implicated in the pathophysiology of most brain diseases, including neurodevelopmental and neurodegenerative disorders. Emerging lines of evidence suggest that statins and Rho GTPase inhibitors are efficacious and have advantageous properties in treatment of different pathologic conditions that are relevant to the central nervous system. Beyond the original role of statins in lowering cholesterol synthesis, they have anti-inflammatory, antioxidant and modulatory effects on signaling pathways. Additionally, Rho GTPase inhibitors and statins share the mevalonate pathway as a common target of their therapeutic actions. In this review, we discuss potential mechanisms through which these drugs, via their role in the mevalonate pathway, exert their neuroprotective effects in neurodegenerative and neurodevelopmental disorders. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Recent progress of laser metrology in chemically reacting flows at onera

    Science.gov (United States)

    Mohamed, A.; Dorval, N.; Vilmart, G.; Orain, M.; George, R.; Scherman, M.; Nafa, M.; Bresson, A.; Attal-Tretout, B.; Lefebvre, M.

    2017-06-01

    This paper presents some of the development actions performed these last years at ONERA using laser spectroscopic techniques to probe chemically reacting flows. Techniques like laser absorption, laser induced fluorescence (LIF), and Raman scattering will be described with focus on present drawbacks as well as expectations from new laser technologies (Interband Cascade Lasers (ICL) diodes, Optical Parametrical Oscillators (OPO), frequency comb, and femto/picosecond lasers) before showing some results of recent applications in ground facilities.

  1. Direct determination of glucose, lactate and triglycerides in blood serum by a tunable quantum cascade laser-based mid-IR sensor

    Science.gov (United States)

    Brandstetter, M.; Volgger, L.; Genner, A.; Jungbauer, C.; Lendl, B.

    2013-02-01

    This work reports on a compact sensor for fast and reagent-free point-of-care determination of glucose, lactate and triglycerides in blood serum based on a tunable (1030-1230 cm-1) external-cavity quantum cascade laser (EC-QCL). For simple and robust operation a single beam set-up was designed and only thermoelectric cooling was used for the employed laser and detector. Full computer control of analysis including liquid handling and data analysis facilitated routine measurements. A high optical pathlength (>100 μm) is a prerequisite for robust measurements in clinical practice. Hence, the optimum optical pathlength for transmission measurements in aqueous solution was considered in theory and experiment. The experimentally determined maximum signal-to-noise ratio (SNR) was around 140 μm for the QCL blood sensor and around 50 μm for a standard FT-IR spectrometer employing a liquid nitrogen cooled mercury cadmium telluride (MCT) detector. A single absorption spectrum was used to calculate the analyte concentrations simultaneously by using a partial-least-squares (PLS) regression analysis. Glucose was determined in blood serum with a prediction error (RMSEP) of 6.9 mg/dl and triglycerides with an error of cross-validation (RMSECV) of 17.5 mg/dl in a set of 42 different patients. In spiked serum samples the lactate concentration could be determined with an RMSECV of 8.9 mg/dl.

  2. Application of clean laser transfer for porphyrin micropatterning

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, T.V., E-mail: kononen@nsc.gpi.ru [Natural Sciences Center, A.M. Prokhorov General Physics Institute, Vavilov str. 38, 119991, Moscow (Russian Federation); Nagovitsyn, I.A. [Natural Sciences Center, A.M. Prokhorov General Physics Institute, Vavilov str. 38, 119991, Moscow (Russian Federation); N.N. Semionov Institute of Chemical Physics, Kosygina str. 4, 119991, Moscow (Russian Federation); Chudinova, G.K. [Natural Sciences Center, A.M. Prokhorov General Physics Institute, Vavilov str. 38, 119991, Moscow (Russian Federation); Mihailescu, I.N. [National Institute for Lasers, Plasma, and Radiation Physics, PO Box MG-54, RO-77125 Bucharest-Magurele (Romania)

    2010-02-15

    Blister-based laser-induced forward transfer is proposed as a promising tool for clean, cold and liquid-free local transfer of various organic substances. The feature of the given technique is non-destructive local deformation of an absorbing metal film on a transparent support avoiding the metal sputtering. Application of the blister-based laser transfer of a Langmuir film to fabricate mesotetraphenylporphyrin micropatterns on a silica substrate has been demonstrated. The metal film thickness is found to be a key parameter, which determines the laser fluence range allowing the clean transfer, predominant mechanism of the blister formation and laser-induced heating of the transferred material. According to the numerical modelling confirmed by UV-vis absorption spectroscopy, the target with 1.5 {mu}m thick titanium film provides negligible heating of the porphyrin transferred by 5 ns laser pulses.

  3. Medical Applications Of CO2 Laser Fiber Optics

    Science.gov (United States)

    McCord, R. C.

    1981-07-01

    In 1978, Hughes Laboratories reported development of fiber optics that were capable of transmitting CO2 laser energy. These fibers are now being tested for medical applications. Wide ranging medical investigation with CO2 lasers has occurred during the twelve years since the first observations of laser hemostasis. Specialists in ophthalmology, neurosurgery, urology, gynecology, otolaryngology, maxillo-facial/plastic surgery, dermatology, and oncology among others, have explored its use. In principle, all these specialists use CO2 laser radiation at 10.6 microns to thermally destroy diseased tissues. As such, CO2 lasers compare and compete with electrosurgical devices. The fundamental difference between these modalities lies in how they generate heat in treated tissue.

  4. Holmium-doped laser materials for eye-safe solid state laser application

    Science.gov (United States)

    Kim, Woohong; Bowman, Steven R.; Baker, Colin; Villalobos, Guillermo; Shaw, Brandon; Sadowski, Bryan; Hunt, Michael; Aggarwal, Ishwar; Sanghera, Jasbinder

    2014-06-01

    Trivalent holmium has 14 laser channels from 0.55 to 3.9 μm. The laser emission of most interest is the transition 5I7→5I8 near 2 μm because of its potential for use in eye-safe systems and medical applications. In this paper, we present our recent results in the development of Ho3+ doped laser materials for eye-safe solid state lasers. We report a calorimetric study of non-radiative losses in two micron pumped holmium doped laser host materials such as silica glass, yttrium aluminum garnet (YAG) crystal and Lu2O3 ceramics. Optical, spectral and morphological properties as well as the lasing performance from highly transparent ceramics are presented.

  5. Adaptive Tunable Laser Spectrometer for Space Applications

    Science.gov (United States)

    Flesch, Gregory; Keymeulen, Didier

    2010-01-01

    An architecture and process for the rapid prototyping and subsequent development of an adaptive tunable laser absorption spectrometer (TLS) are described. Our digital hardware/firmware/software platform is both reconfigurable at design time as well as autonomously adaptive in real-time for both post-integration and post-launch situations. The design expands the range of viable target environments and enhances tunable laser spectrometer performance in extreme and even unpredictable environments. Through rapid prototyping with a commercial RTOS/FPGA platform, we have implemented a fully operational tunable laser spectrometer (using a highly sensitive second harmonic technique). With this prototype, we have demonstrated autonomous real-time adaptivity in the lab with simulated extreme environments.

  6. Secure key distribution applications of chaotic lasers

    Science.gov (United States)

    Jiang, Ning; Xue, Chenpeng; Lv, Yunxin; Qiu, Kun

    2016-11-01

    Chaotic semiconductor laser is a good candidate for secure communication and high-speed true random bit generator, for its characteristics of broad bandwidth and prominent unpredictability. Based on the synchronization property and true random bit generation characteristic of chaotic semiconductor lasers, physical secure key distribution is available. In this work, we majorly show three key distribution schemes stemming from synchronized chaotic semiconductor lasers or chaos-based key exchange protocol. The numerical results demonstrate that the security of the chaos-synchronization-based key distribution scheme can be physically enhanced by adopting dynamic synchronization scheme or encrypted key generation, and that of key distribution with chaos-based key exchange protocol is dependent on the security of the exchange protocol and finally determined by the difficulty of regeneration the chaos system accurately.

  7. CO2 with Mechanical Subcooling vs. CO2 Cascade Cycles for Medium Temperature Commercial Refrigeration Applications Thermodynamic Analysis

    Directory of Open Access Journals (Sweden)

    Laura Nebot-Andrés

    2017-09-01

    Full Text Available A recent trend to spread the use of CO2 refrigeration cycles in warm regions of the world is to combine a CO2 cycle with another one using a high performance refrigerant. Two alternatives are being considered: cascade and mechanical subcooling systems. Both respond to a similar configuration of the refrigeration cycle, they being based on the use of two compressors and same number of heat exchangers. However, the compressor, heat exchanger sizes and energy performance differ a lot between them. This work, using experimental relations for CO2 and R1234yf semi-hermetic compressors analyzes in depth both alternatives under the warm climate of Spain. In general, it was concluded that the CO2 refrigeration solution with mechanical subcooling would cover all the conditions with high overall energy efficiency, thus it being recommended for further extension of the CO2 refrigeration applications.

  8. Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Hongming [Laboratoire de Physicochimie de l' Atmosphère, Université du Littoral Côte d' Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque (France); Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 1125, 350 Shushanhu Road, Hefei, Anhui 230031 (China); Maamary, Rabih; Fertein, Eric; Chen, Weidong, E-mail: chen@univ-littoral.fr [Laboratoire de Physicochimie de l' Atmosphère, Université du Littoral Côte d' Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque (France); Gao, Xiaoming [Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 1125, 350 Shushanhu Road, Hefei, Anhui 230031 (China); Sigrist, Markus W. [ETH Zurich, Institute for Quantum Electronics, HPT H4.1, Auguste-Piccard-Hof 1, CH-8093 Zürich (Switzerland)

    2015-03-09

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm{sup −1} was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ∼40 mm{sup 3}) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by direct absorption spectroscopy involving a ∼109.5 m multipass cell and a distributed feedback QCL. A minimum detection limit (MDL) of 66 ppbv (1 σ) HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6 × 10{sup −8 }cm{sup −1} W/Hz{sup 1/2}. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding 1σ minimum detected absorption coefficient is ∼1.1 × 10{sup −7 }cm{sup −1} (MDL ∼ 3 ppbv) in 1 s and ∼1.1 × 10{sup −8 }cm{sup −1} (MDL ∼ 330 pptv) in 150 s, respectively, with 1 W laser power.

  9. Tailoring Laser Propulsion for Future Applications in Space

    Science.gov (United States)

    Eckel, Hans-Albert; Scharring, Stefan

    2010-10-01

    Pulsed laser propulsion may turn out as a low cost alternative for the transportation of small payloads in future. In recent years DLR investigated this technology with the goal of cheaply launching small satellites into low earth orbit (LEO) with payload masses on the order of 5 to 10 kg. Since the required high power pulsed laser sources are yet not at the horizon, DLR focused on new applications based on available laser technology. Space-borne, i.e. in weightlessness, there exist a wide range of missions requiring small thrusters that can be propelled by laser power. This covers space logistic and sample return missions as well as position keeping and attitude control of satellites. First, a report on the proof of concept of a remote controlled laser rocket with a thrust vector steering device integrated in a parabolic nozzle will be given. Second, the road from the previous ground-based flight experiments in earth's gravity using a 100-J class laser to flight experiments with a parabolic thruster in an artificial 2D-zero gravity on an air cushion table employing a 1-J class laser and, with even less energy, new investigations in the field of laser micro propulsion will be reviewed.

  10. Power blue and green laser diodes and their applications

    Science.gov (United States)

    Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

    2013-03-01

    InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

  11. Biological applications of ultraviolet free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J.C.

    1997-10-01

    This review examines the possibilities for biological research using the three ultraviolet free-electron lasers that are nearing operational status in the US. The projected operating characteristics of major interest in biological research of the free-electron lasers at Brookhaven National Laboratory, the Thomas Jefferson National Accelerator Facility, and Duke University are presented. Experimental applications in the areas of far- and vacuum ultraviolet photophysics and photochemistry, structural biology, environmental photobiology, and medical research are discussed and the prospects for advances in these areas, based upon the characteristics of the new ultraviolet free-electron lasers, are evaluated.

  12. Investigation of ferrofluid nanostructure by laser light scattering: medical applications

    Science.gov (United States)

    Nepomnyashchaya, E. K.; Velichko, E. N.; Pleshakov, I. V.; Aksenov, E. T.; Savchenko, E. A.

    2017-05-01

    Investigation of ferrofluids nanostructure by the laser light scattering technique is presented. Experimental studies involved measurements of the intensity of the laser radiation scattered by ferrofluid particles in interaction with albumin and under the influence of magnetic field. The effects of the magnitude and duration of the applied magnetic field on the formation of aggregates of magnetic nanoparticles and also the influence of magnetic fluids of different concentrations on blood proteins are considered. The findings may be useful for medical applications.

  13. Laser Science and its Applications in Prosthetic Rehabilitation

    OpenAIRE

    Gounder, Revathy; Gounder, Srinivasan

    2016-01-01

    The minimal invasive nature of lasers, with quick tissue response and healing has made them a very attractive technology in various fields of dentistry which serves as a tool to create a better result than ever before. The rapid development of lasers and their wavelengths with variety of applications on soft and hard tissues may continue to have major impact on the scope and practice in prosthetic dentistry. The purpose of this article is to make every clinician familiar with the fundamentals...

  14. Quantum Cascade Laser Master-Oscillator Power-Amplifier with 1.5-W Output Power at 300 K

    Science.gov (United States)

    2011-05-25

    PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION ...Prog. Phys. 64, IS33-1601 (2001). 3. A. A. Kostercv aod’F.K. Tittel, " Chemica ] sensors based on quantumcascadc lasers," IEEE 1. Quantum Electron. 38

  15. Diffraction Gratings for High-Intensity Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Britten, J

    2008-01-23

    The scattering of light into wavelength-dependent discrete directions (orders) by a device exhibiting a periodic modulation of a physical attribute on a spatial scale similar to the wavelength of light has been the subject of study for over 200 years. Such a device is called a diffraction grating. Practical applications of diffraction gratings, mainly for spectroscopy, have been around for over 100 years. The importance of diffraction gratings in spectroscopy for the measurement of myriad properties of matter can hardly be overestimated. Since the advent of coherent light sources (lasers) in the 1960's, applications of diffraction gratings in spectroscopy have further exploded. Lasers have opened a vast application space for gratings, and apace, gratings have enabled entirely new classes of laser systems. Excellent reviews of the history, fundamental properties, applications and manufacturing techniques of diffraction gratings up to the time of their publication can be found in the books by Hutley (1) and more recently Loewen and Popov (2). The limited scope of this chapter can hardly do justice to such a comprehensive subject, so the focus here will be narrowly limited to characteristics required for gratings suitable for high-power laser applications, and methods to fabricate them. A particular area of emphasis will be on maximally-efficient large-aperture gratings for short-pulse laser generation.

  16. Applications of robotics in laser welding

    NARCIS (Netherlands)

    de Graaf, M.W.; Aarts, Ronald G.K.M.; Katayama, Seiji

    2013-01-01

    This chapter describes how seam-tracking sensors can be integrated in a robotic laser welding system for automatic teaching of the seam trajectory as well as for correcting small errors from a pre-defined seam trajectory. Calibration procedures are required to derive accurate transformations of

  17. What makes for a successful laser application

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove

    1997-01-01

    of their lasers on the straight forward jobs. And if every things goes perfect, they might even manage to make a good test of one of the possible jobs. But, they have some jobs laying over from yesterday, and they miss some optical components to be able to demonstrate some af these jobs correctly, and tommorrow...

  18. Progress in the applicability of plasma X-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kuehl, T., E-mail: T.Kuehl@gsi.de; Aurand, B.; Bagnoud, V.; Ecker, B.; Eisenbarth, U. [GSI (Germany); Guilbaud, O. [Universite Paris Sud (France); Fils, J.; Goette, S. [GSI (Germany); Habib, J. [Universite Paris Sud (France); Hochhaus, D.; Javorkova, D. [GSI (Germany); Neumayer, P. [Extreme Matter Institute, EMMI (Germany); Kazamias, S.; Pittman, M.; Ros, D. [Universite Paris Sud (France); Seres, J.; Spielmann, Ch. [Friedrich Schiller-University (Germany); Zielbauer, B.; Zimmer, D. [GSI (Germany)

    2010-02-15

    Proposed as satellite-based weapons during the 1980s, X-ray lasing was for a long time only achieved with enormous amounts of pump energy in either nuclear explosions or at kilojoule-class laser installations. During the last few years a tremendous development was achieved, most visible in the realisation of the FEL lasers at DESY and SLAC. As important for a wider applicability is the enormous reduction in pump energy for laser pumped plasma X-ray lasers, which now brings such devices into the range of applications for diagnostics and spectroscopy even in smaller laboratories. Main developments were the transient excitation scheme and the optimized pumping concepts. This paper concentrates on developments at the GSI Helmholtzcenter at Darmstadt aiming towards reliable X-ray laser sources in the range from 50 to several 100 eV. The main driving forces for the laser development at GSI are the possible application for the spectroscopy of Li-like ions in the storage ring ESR and the future storage ring NESR at FAIR, and the interest in novel plasma diagnostics.

  19. Sigma-delta receive beamformer based on cascaded reconstruction for ultrasound imaging application.

    Science.gov (United States)

    Cheong, Jia Hao; Lam, Yvonne Ying Hung; Tiew, Kei Tee; Koh, Liang Mong

    2008-09-01

    A pre-delay reconstruction sigma-delta beamformer (SDBF) was recently proposed to achieve a higher level of integration in ultrasound imaging systems. Nevertheless, the high-order reconstruction filter used in each channel of SDBF makes the beamformer highly complex. The beamformer can be simplified by reconstructing the signal after the delay-and-sum process with only one filter. However, this post-delay reconstruction-based design degrades image quality when dynamic focusing is performed. This paper shows that employing a simple pre-delay filter is sufficient to achieve similar performance as conventional pre-delay reconstruction SDBF, as long as the pre-delay filter provides the required pre-delay signal to-quantization noise ratio (SQNR). Based on this finding, we proposed a cascaded reconstruction beamformer that uses a boxcar filter as the pre-delay filter in each channel. Simulations using real phantom data demonstrate that the proposed beamforming method can achieve a contrast resolution comparable to that of the pre-delay reconstruction beamforming method. In addition, the hardware can be greatly simplified compared with the pre-delay reconstruction beamformers.

  20. Universal Voltage Conveyor and its Novel Dual-Output Fully-Cascadable VM APF Application

    Directory of Open Access Journals (Sweden)

    Norbert Herencsar

    2017-03-01

    Full Text Available This letter presents a novel realization of a voltage-mode (VM first-order all-pass filter (APF with attractive features. The proposed circuit employs a single readily available six-terminal active device called as universal voltage conveyor (UVC and only grounded passive components, which predict its easy monolithic integration with desired circuit simplicity. The auxiliary voltage input (W and output (ZP, ZN terminals of the device fully ensure easy cascadability of VM APF, since the input and output terminal impedances are theoretically infinitely high and zero, respectively. Moreover, thanks to mutually inverse outputs of the UVC, the proposed filter simultaneously provides both inverting and non-inverting outputs from the same configuration. All of these features make the UVC a unique active device currently available in the literature. The behavior of the filter was experimentally measured using the readily available UVC-N1C 0520 chip, which was produced in cooperation with ON Semiconductor Czech Republic, Ltd.

  1. Evolution and applications of lasers in oral and maxillofacial surgery

    Directory of Open Access Journals (Sweden)

    Luke Nandu Kale

    2017-01-01

    Full Text Available With the advent of new and developing technology into the field of dentistry, it becomes increasingly important for dentists to become familiar with these developing techniques. The use of lasers in oral and maxillofacial surgery has seen a substantial increase in both, applications of lasers for different techniques, and also the number of surgeons opting to use them on a regular basis. This article serves to update practitioners on the development and current applications of these modern tools in regular practice so as to efficiently perform dental treatment and minimize complications associated with conventional techniques. The authors have reviewed articles on the subject from PubMed, Science Direct, and relevant textbooks so as to compile an accurate history of the evolution of lasers, its introduction to the field of dentistry and also its current applications in the field of oral and maxillofacial surgery.

  2. High-power diode lasers and their direct industrial applications

    Science.gov (United States)

    Loosen, Peter; Treusch, Hans-Georg; Haas, C. R.; Gardenier, U.; Weck, Manfred; Sinnhoff, V.; Kasperowski, S.; vor dem Esche, R.

    1995-04-01

    The paper summarizes activities of the two Fraunhofer-Institutes ILT and IPT concerning the development of high-power laser-diode stacks and their direct industrial applications. With microchannel coolers in copper technology and ultra-precision machined micro-optics a stack of 330 - 400 W total power with a maximum intensity of the focused beam of 2 104 W/cm2 has been built and tested in first applications. By further improvements of the lens-fabrication and -alignment technology as well as increase of the number of stacked diodes an output power in the kW-range and intensities up to about 105 W/cm2 shall be achieved in the near future. Applications of such laser sources in surface technology, in the processing of plastics, in laser-assisted machining and in brazing are discussed.

  3. Applications of laser wakefield accelerator-based light sources

    Science.gov (United States)

    Albert, Félicie; Thomas, Alec G. R.

    2016-11-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. We first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  4. Electrospun Polymer Fiber Lasers for Applications in Vapor Sensing

    DEFF Research Database (Denmark)

    Krämmer, Sarah; Laye, Fabrice; Friedrich, Felix

    2017-01-01

    A sensing approach based on laser emissionfrom polymer fiber networks is presented. Poly(methyl methacrylate) (PMMA) fibers doped with a laser dye are fabricated by electrospinning. They form random loop resonators, which show laser emission upon optical pumping. The shift of the spectral positio...... in the transient shift of the lasing peaks can be used to discriminate ethanol and methanol vapor in mixtures of them. The sensing mechanism is expected to be applicable to other solvent vapors that cause polymer swelling.......A sensing approach based on laser emissionfrom polymer fiber networks is presented. Poly(methyl methacrylate) (PMMA) fibers doped with a laser dye are fabricated by electrospinning. They form random loop resonators, which show laser emission upon optical pumping. The shift of the spectral position...... feature excellent sensing performance due to the large overlap (more than 80%) of light field and transducer. The shift of the laser modes results from the swelling of the polymer when exposed to solvent vapors. Due to distinctly different diffusion coefficients in polymers, the uptake dynamics reflected...

  5. Ground-to-orbit laser propulsion: Advanced applications

    Energy Technology Data Exchange (ETDEWEB)

    Kare, J.T.

    1990-01-01

    Laser propulsion uses a large fixed laser to supply energy to heat an inert propellant in a rocket thruster. Such a system has two potential advantages: extreme simplicity of the thruster, and potentially high performance -- particularly high exhaust velocity. By taking advantage of the simplicity of the thruster, it should be possible to launch small (10--1000 kg) payloads to orbit using roughly 1 MW of average laser power per kg of payload. The incremental cost of such launches would be of order $200/kg for the smallest systems, decreasing to essentially the cost of electricity to run the laser (a few times $10/kg) for large systems. Although the individual payload size would be small, a laser launch system would be inherently high-volume, with the capacity to launch tens of thousands of payloads per year. Also, with high exhaust velocity, a laser launch system could launch payloads to high velocities -- geosynchronous transfer, Earth escape, or beyond -- at a relatively small premium over launches to LEO. In this paper, we briefly review the status of pulsed laser propulsion, including proposals for advanced vehicles. We then discuss qualitatively several unique applications appropriate to the early part of the next century, and perhaps valuable well into the next millenium: space habitat supply, deep space mission supply, nuclear waste disposal, and manned vehicle launching.

  6. Clinical application of CO2 laser in periodontal treatment

    Science.gov (United States)

    Hayase, Yasuhiro

    1994-09-01

    CO2 lasers in particular are expected to have many dental applications because the CO2 laser beam exhibits strong tissue transpirative actions, such as instant coagulation, carbonization, and vaporization, and because its wavelength at 10.6 micrometers is fully absorbed by water so that the ability to make precise incisions with a high degree of safety is excellent, without damaging the deep tissues. However, clinical application of the CO2 laser has been slowed since a fiber which can conduct the laser beam to the oral cavity has only recently developed. This new fiber is an extremely flexible fiber with a minimum bending radius of 20 mm and utilizes pulse wave modes that have improved the handling characteristics in the mouth, and this has enabled us to apply the CO2 laser to a variety of periodontal conditions. The aim of this study was to evaluate the effectiveness of CO2 lasers for the early treatment of inflammation and pain relief of acute periodontitis, curettage of periodontal pockets, healing after excision of gingiva, and early improvement of gingivitis.

  7. Status and future prospects of laser fusion and high power laser applications

    Science.gov (United States)

    Mima, Kunioki

    2010-08-01

    In Asia, there are many institutes for the R&D of high power laser science and applications. They are 5 major institutes in Japan, 4 major institutes in China, 2 institutes in Korea, and 3 institutes in India. The recent achievements and future prospects of those institutes will be over viewed. In the laser fusion research, the FIREX-I project in Japan has been progressing. The 10kJ short pulse LFEX laser has completed and started the experiments with a single beam. About 1kJ pulse energy will be injected into a cone target. The experimental results of the FIREX experiments will be presented. As the target design for the experiments, a new target, namely, a double cone target was proposed, in which the high energy electrons are well confined and the heating efficiency is significantly improved. Together with the fusion experiments, Osaka University has carried out laboratory astrophysics experiments on photo ionizing plasmas to observe a unique X-ray spectrum from non-LTE plasmas. In 2008, Osaka university has started a new Photon research center in relation with the new program: Consortium for Photon Science and Technology: C-PhoST, in which ultra intense laser plasmas research and related education will be carried out for 10 years. At APRI, JAEA, the fundamental science on the relativistic laser plasmas and the applications of laser particle acceleration has been developed. The application of laser ion acceleration has been investigated on the beam cancer therapy since 2007. In China, The high power glass laser: Shenguan-II and a peta watt beam have been operated to work on radiation hydro dynamics at SIOFM Shanghai. The laser material and optics are developed at SIOFM and LFRC. The IAPCM and the IOP continued the studies on radiation hydrodynamics and on relativistic laser plasmas interactions. At LFRC in China, the construction of Shenguan III glass laser of 200kJ in blue has progressed and will be completed in 2012. Together with the Korean program, I will

  8. Highly-reliable laser diodes and modules for spaceborne applications

    Science.gov (United States)

    Deichsel, E.

    2017-11-01

    Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

  9. Laser characteristics and interferometric process and sensor applications

    Science.gov (United States)

    Glatz, Otto

    2005-04-01

    Begin Fiber Bragg Gratings (FBGs) are basic elements in DWDM technology. They are produced by UV illumination. UV light sources have been steadily improved to meet the demands of FBG writing industry. We want to characterize some parameters of interest of a simple, line-narrowed excimer laser source, its improvements and contribution to interferometric non-proximity FBG writing. Parameters of interest to be discussed are the temporal and spatial coherence length, the beam stability and spectrum control of produced FBG. With a temporal coherence length of ~ 5 mm it is possible to utilize cost efficient excimer laser technology for the interferometric non-proximity FBG writing process. Correspondingly the line-narrowed Excimer laser can replace expensive frequency doubled Argon ion lasers driving interferometric FBG writing set-ups in production and R & D. Beyond it FBGs for sensor applications play an important role. They have the potential for the measurement of strain / deformation and temperature with applications including monitoring of highways, bridges, aerospace components and chemical and biological sensors. We want to discuss the requirements for excimer lasers for this application: The spatial coherence length, beam profile, pointing and energy stability.

  10. Application of the femtosecond laser LASIK microkeratome in eye banking.

    Science.gov (United States)

    Shah, Sanket U; Gritz, David C

    2012-07-01

    To review the literature for recent advancements in the femtosecond laser technology with regard to its applications in corneal transplantation and eye banking. Advancements in corneal surgery have encouraged the use of disease-specific corneal subcomponents, utilized in procedures such as anterior-lamellar keratoplasty and endothelial keratoplasty, instead of traditional transplant procedures to minimize adverse effects of penetrating keratoplasty. Femtosecond laser microkeratomes can precisely create flaps for such transplant procedures, achieve better wound stability, and promote healing by shaped wound configurations. Laser microkeratomes have been compared to traditional mechanical microkeratomes for keratoplasty procedures from various aspects and are superior in some aspects and offer unique capabilities. Femtosecond laser applications in eye banking include preparation of donor and recipient corneas for use in penetrating keratoplasty, anterior-lamellar keratoplasty, and endothelial keratoplasty. Advantages of femtosecond laser microkeratomes include higher precision of the cut, ability to achieve thinner flaps, and wound configurations that allow greater wound stability, shorter recovery time, and less postoperative pain. However, cost and availability at the eye-bank level may hinder widespread and immediate application.

  11. Temporal rainfall disaggregation using a multiplicative cascade model for spatial application in urban hydrology

    Science.gov (United States)

    Müller, H.; Haberlandt, U.

    2018-01-01

    Rainfall time series of high temporal resolution and spatial density are crucial for urban hydrology. The multiplicative random cascade model can be used for temporal rainfall disaggregation of daily data to generate such time series. Here, the uniform splitting approach with a branching number of 3 in the first disaggregation step is applied. To achieve a final resolution of 5 min, subsequent steps after disaggregation are necessary. Three modifications at different disaggregation levels are tested in this investigation (uniform splitting at Δt = 15 min, linear interpolation at Δt = 7.5 min and Δt = 3.75 min). Results are compared both with observations and an often used approach, based on the assumption that a time steps with Δt = 5.625 min, as resulting if a branching number of 2 is applied throughout, can be replaced with Δt = 5 min (called the 1280 min approach). Spatial consistence is implemented in the disaggregated time series using a resampling algorithm. In total, 24 recording stations in Lower Saxony, Northern Germany with a 5 min resolution have been used for the validation of the disaggregation procedure. The urban-hydrological suitability is tested with an artificial combined sewer system of about 170 hectares. The results show that all three variations outperform the 1280 min approach regarding reproduction of wet spell duration, average intensity, fraction of dry intervals and lag-1 autocorrelation. Extreme values with durations of 5 min are also better represented. For durations of 1 h, all approaches show only slight deviations from the observed extremes. The applied resampling algorithm is capable to achieve sufficient spatial consistence. The effects on the urban hydrological simulations are significant. Without spatial consistence, flood volumes of manholes and combined sewer overflow are strongly underestimated. After resampling, results using disaggregated time series as input are in the range of those using observed time series. Best

  12. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    Science.gov (United States)

    Pitt, Joseph; Le Breton, Michael; Allen, Grant; Percival, Carl; Gallagher, Martin; Bauguitte, Stephane; O'Shea, Sebastian; Muller, Jennifer; Zahniser, Mark; Pyle, John; Palmer, Paul

    2016-04-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  13. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    Science.gov (United States)

    Diaz, Adrian; Thomas, Benjamin; Castillo, Paulo; Gross, Barry; Moshary, Fred

    2016-06-01

    Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS). The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms) and are achieved at sufficient range (up to 40 m, ~ 130 feet) with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  14. The SPIRIT airborne instrument: a three-channel infrared absorption spectrometer with quantum cascade lasers for in situ atmospheric trace-gas measurements

    Science.gov (United States)

    Catoire, Valéry; Robert, Claude; Chartier, Michel; Jacquet, Patrick; Guimbaud, Christophe; Krysztofiak, Gisèle

    2017-09-01

    An infrared absorption spectrometer called SPIRIT (SPectromètre Infra-Rouge In situ Toute altitude) has been developed for airborne measurements of trace gases in the troposphere. At least three different trace gases can be measured simultaneously every 1.6 s using the coupling of a single Robert multipass optical cell with three Quantum Cascade Lasers (QCLs), easily interchangeable to select species depending on the scientific objectives. Absorptions of the mid-infrared radiations by the species in the cell at reduced pressure (path lengths adjustable up to 167.78 m, are quantified using an HgCdTe photodetector cooled by Stirling cycle. The performances of the instrument are assessed: a linearity with a coefficient of determination R 2 > 0.979 for the instrument response is found for CO, CH4, and NO2 volume mixing ratios under typical tropospheric conditions. In-flight comparisons with calibrated gas mixtures allow to show no instrumental drift correlated with atmospheric pressure and temperature changes (when vertical profiling) and to estimate the overall uncertainties in the measurements of CO, CH4, and NO2 to be 0.9, 22, and 0.5 ppbv, respectively. In-flight precision (1 σ) for these species at 1.6 s sampling is 0.3, 5, and 0.3 ppbv, respectively.

  15. High resolution quantum cascade laser spectroscopy of the simplest Criegee intermediate, CH2OO, between 1273 cm-1 and 1290 cm-1

    Science.gov (United States)

    Chang, Yuan-Pin; Merer, Anthony J.; Chang, Hsun-Hui; Jhang, Li-Ji; Chao, Wen; Lin, Jim-Min, Jr.

    2017-06-01

    The region 1273-1290 cm-1 of the ν4 fundamental of the simplest Criegee intermediate, CH2OO, has been measured using a quantum cascade laser transient absorption spectrometer, which offers greater sensitivity and spectral resolution (light sources. Gas phase CH2OO was generated from the reaction of CH2I + O2 at 298 K and 4 Torr. The analysis of the absorption spectrum has provided precise values for the vibrational frequency and the rotational constants, with fitting errors of a few MHz. The determined ratios of the rotational constants, A'/A″ = 0.9986, B'/B″ = 0.9974, and C'/C″ = 1.0010, and the relative intensities of the a- and b-type transitions, 90:10, are in good agreement with literature values from a theoretical calculation using the MULTIMODE approach, based on a high-level ab initio potential energy surface. The low-K (=Ka) lines can be fitted extremely well, but rotational perturbations by other vibrational modes disrupt the structure for K = 4 and K ≥ 6. Not only the spectral resolution but also the detection sensitivity of CH2OO IR transitions has been greatly improved in this work, allowing for unambiguous monitoring of CH2OO in kinetic studies at low concentrations.

  16. Effect of conduction band non-parabolicity on the optical gain of quantum cascade lasers based on the effective two-band finite difference method

    Science.gov (United States)

    Cho, Gookbin; Kim, Jungho

    2017-09-01

    We theoretically investigate the effect of conduction band non-parabolicity (NPB) on the optical gain spectrum of quantum cascade lasers (QCLs) using the effective two-band finite difference method. Based on the effective two-band model to consider the NPB effect in the multiple quantum wells (QWs), the wave functions and confined energies of electron states are calculated in two different active-region structures, which correspond to three-QW single-phonon and four-QW double-phonon resonance designs. In addition, intersubband optical dipole moments and polar-optical-phonon scattering times are calculated and compared without and with the conduction band NPB effect. Finally, the calculation results of optical gain spectra are compared in the two QCL structures having the same peak gain wavelength of 8.55 μm. The gain peaks are greatly shifted to longer wavelengths and the overall gain magnitudes are slightly reduced when the NPB effect is considered. Compared with the three-QW active-region design, the redshift of the peak gain is more prominent in the four-QW active-region design, which makes use of higher electronic states for the lasing transition.

  17. Proton implantation for electrical insulation of the InGaAs/InAlAs superlattice material used in 8-15 μm-emitting quantum cascade lasers

    Science.gov (United States)

    Kirch, J. D.; Kim, H.; Boyle, C.; Chang, C.-C.; Mawst, L. J.; Lindberg, D.; Earles, T.; Botez, D.; Helm, M.; von Borany, J.; Akhmadaliev, S.; Böttger, R.; Reyner, C.

    2017-02-01

    We demonstrate the conversion of lattice-matched InGaAs/InAlAs quantum-cascade-laser (QCL) active-region material into an effective current-blocking layer via proton implantation. A 35-period active region of an 8.4 μm-emitting QCL structure was implanted with a dose of 5 × 1014 cm-2 protons at 450 keV to produce a vacancy concentration of ˜1019 cm-3. At room temperature, the sheet resistance, extracted from the Hall measurements, increases by a factor of ˜240 with respect to that of an unimplanted material. Over the 160-320 K temperature range, the activation energy of the implanted-material Hall sheet-carrier density is 270 meV. The significant increase in room-temperature sheet resistance indicates that upon implantation deep carrier traps have been formed in the InAlAs layers of the superlattice. Fabricated mesas show effective current blocking, at voltages ≥10 V, up to at least 350 K. Thus, the implanted InGaAs/InAlAs superlattices are highly resistive to at least 350 K heat sink temperature. Such implanted material should prove useful for effective current confinement in 8-15 μm-emitting InP-based single-emitter QCL structures as well as in resonant leaky-wave coupled phase-locked arrays of QCLs.

  18. Active Stand-off Detection of Gas Leaks Using a Short Range Hard-target Backscatter Differential Optical Absorption System Based on a Quantum Cascade Laser Transmitter

    Directory of Open Access Journals (Sweden)

    Diaz Adrian

    2016-01-01

    Full Text Available Fugitive gas emissions from agricultural or industrial plants and gas pipelines are an important environmental concern as they can contribute to the global increase of greenhouse gas concentration. Moreover, they are also a security and safety concern because of possible risk of fire/explosion or toxicity. This study presents gas concentration measurements using a quantum cascade laser open path system (QCLOPS. The system retrieves the pathaveraged concentration of N2O and CH4 by collecting the backscattered light from a scattering target. The gas concentration measurements have a high temporal resolution (68 ms and are achieved at sufficient range (up to 40 m, ~ 130 feet with a detection limit of 2.6 ppm CH4 and 0.4 ppm for N2O. Given these characteristics, this system is promising for mobile/multidirectional remote detection and evaluation of gas leaks. The instrument is monostatic with a tunable QCL emitting at ~ 7.7 μm wavelength range. The backscattered radiation is collected by a Newtonian telescope and focused on an infrared light detector. Puffs of N2O and CH4 are released along the optical path to simulate a gas leak. The measured absorption spectrum is obtained using the thermal intra-pulse frequency chirped DFB QCL and is analyzed to obtain path averaged gas concentrations.

  19. Optimization of growth conditions for InGaAs/InAlAs/InP quantum cascade lasers by metalorganic chemical vapor deposition

    Science.gov (United States)

    Huang, Yong; Ryou, Jae-Hyun; Dupuis, Russell D.; Pflügl, Christian; Capasso, Federico; Sun, Kewei; Fischer, Alec M.; Ponce, Fernando A.

    2011-02-01

    We investigate the growth conditions for lattice-matched InGaAs/InAlAs/InP quantum cascade lasers (QCLs) by metalorganic chemical vapor deposition (MOCVD). Effect of substrate misorientation, growth temperature, and V/III ratios of InGaAs and InAlAs layers on the surface morphology, optical quality, and impurity incorporation were systematically studied. It was found that epitaxial layers and multi-quantum-well structures grown at 720 °C with V/III ratios of 116 for InGaAs and 21 for InAlAs on InP substrates with an off-cut angle of ˜0.06° exhibit a stable step-flow growth and low oxygen and carbon contamination. Using these conditions, a ˜11.3-μm-thick QCL with an emission wavelength at ˜9.2 μm was grown and fabricated, which demonstrated excellent structural quality and operated at room temperature in pulsed mode with a threshold current density of 2.0 kA/cm 2 and a slope efficiency of 550 mW/A.

  20. Bulk and trace detection of ammonia and hydrogen peroxide using quantum cascade laser technology - a tool for identifying improvised explosive devices

    Science.gov (United States)

    Lindley, Ruth; Normand, Erwan; McCulloch, Michael; Black, Paul; Howieson, Iain; Lewis, Colin; Foulger, Brian

    2008-10-01

    The type of explosive materials used in terrorist activities has seen a gradual shift from those that are commonly manufactured but difficult to obtain, such as trinitrotoluene (TNT) and nitroglycerine (NG), to improvised explosive devices (IEDs) made from substances that are more readily available. This shift has placed an emphasis on development of instruments capable of detecting IEDs and their precursors, which are often small, volatile molecules well suited to detection through mid-infrared absorption spectroscopy. Two such examples are ammonia, a breakdown product of ammonium nitrate and urea nitrate, and hydrogen peroxide, an efficient oxidiser used in the production of triacetone triperoxide (TATP) and hexamethyl triperoxide diamine (HMTD). At this meeting in 2007 we presented results of a hydrogen peroxide detection portal utilising quantum cascade laser (QCL) technology. This trace detection system has since undergone significant development to improve sensitivity and selectivity, and the results of this will be presented alongside those of a similar system configured for bulk detection of ammonia. Detection of ammonia produced from the breakdown of ammonium nitrate has been demonstrated, both on the optical bench and in a walkthrough portal. This research has been supported by the UK government.

  1. Sensitive detection of nitric oxide using a 5.26 μm external cavity quantum cascade laser based QEPAS sensor

    Science.gov (United States)

    Tittel, Frank K.; Dong, Lei; Lewicki, Rafal; Lee, George; Peralta, Adjani; Spagnolo, Vincenzo

    2012-01-01

    The development and performance of a continuous wave (CW), thermoelectrically cooled (TEC) external cavity quantum cascade laser (EC-QCL) based sensor for quantitative measurements of nitric oxide (NO) concentrations in exhaled breath will be reported. Human breath contains ~ 400 different chemical species, usually at ultra low concentration levels, which can serve as biomarkers for the identification and monitoring of human diseases or wellness states. By monitoring exhaled NO concentration levels, a fast non-invasive diagnostic method for treatment of patients with asthma and chronic obstructive pulmonary disease (COPD) is feasible. The NO concentration measurements are performed with a 2f wavelength modulation based quartz enhanced photoacoustic spectroscopy (QEPAS) technique, which is very suitable for real time breath measurements, due to the fast gas exchange inside a compact QEPAS gas cell (<5 mm3 typical volume). In order to target the optimal interference free NO R (6.5) absorption doublet at 1900.08 cm-1(λ~5.263 μm) a Daylight Solutions Inc. widely tunable, mode-hop free 100 mW EC-QCL was used. The sensor reference channel includes a 10 cm long reference cell, filled with a 0.5% NO in N2 at 150 Torr, which is used for line-locking purpose. A minimum detection limit (1σ) for the EC-QCL based line locked NO sensor is ~5 ppbv with a 1 sec update time by a custom built control QCL compatible electronics unit.

  2. Laser data transmission with the application of reflectance modulator

    Science.gov (United States)

    Knysak, Piotr; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek; Traczyk, Maciej

    2016-12-01

    The article presents the main aspects related to the development of nonconventional asymmetric laser data transmission system. It describes the principle of data transmission in both the direction away from the laser transmitter, wherein a pulse position modulation is used, and in the opposite direction, where the modulation of the reflected radiation is performed. The results presented in the article confirm the possibility of using the described technology in the civilian area for monitoring and telemetry, where devices without radiation sources are taken into account. In military applications, the system can be used to identify own objects and forces on the battlefield by the application of pulsed laser rangefinders which are currently a standard battle equipment.

  3. Therapeutic implications of nonablative laser application neurosurgery: future possibilities

    Science.gov (United States)

    Rymer, William Z.; Lin, Shien-Fong; Wesselmann, Ursula

    1990-06-01

    The application of pulsed or CW infrared lasers to peripheral nerves of mammalian subjects at subablative intensities has shown that action potential propagation is impaired preferentially in slowly conducting axons, and that these laser effects also impair axoplasmic transport over a much longer time period. Parallel studies of afferent processing in the dorsal gray matter of a mammalian spinal cord indicate that synaptic transmission is modified at even lower energy levels. Given that small diameter nerve fibers are concerned primarily with pain transmission, and given further that the superficial regions of dorsal gray matter in the spinal cord are concerned almost exclusively with pain processing, application of infrared lasers to these areas may prove to have short or even long term anesthetic actions.

  4. Mid - infrared solid state lasers for spectroscopic applications

    Science.gov (United States)

    Terekhov, Yuri

    This work is devoted to study of novel high power middle-infrared (Mid-IR) laser sources enabling development of portable platform for sensing of organic molecules with the use of recently discovered Quartz Enhanced Photo Acoustic Spectroscopy (QEPAS). The ability to detect small concentrations is beneficial to monitor atmosphere pollution as well for biomedical applications such as analysis of human breath to detect earlier stages of cancer or virus activities. A QEPAS technique using a quartz tuning fork (QTF) as a detector enables a strong enhancement of measured signal when pump laser is modulated with a frequency coinciding with a natural frequency of a QTF. It is known that the detectability of acousto-optics based sensors is proportional to the square root of the laser intensity used for detection of analyte. That is the reason why commercially available semiconductor Mid-IR lasers having small output power limit sensitivity of modern QEPAS based sensors. The lack of high power broadly tunable lasers operating with a modulation frequency of quartz forks (~ 32.768 kHz) is the major motivation of this study. Commercially available Mid-IR (2-3.3 microm), single frequency, continuous wave (CW) fiber pumped lasers based on transition metal doped chalcogenides (e.g. Cr:ZnSe) prove to be efficient laser sources for organic molecules detection. However, their direct modulation is limited to several kHz, and cannot be directly used in combination with QEPAS. Hence, one objective of this work is to study and develop fiber laser pumped Ho:YAG (Er:YAG)/Cr:ZnSe tandem laser system/s. Ho (Holmium) and/or Er (Erbium) ions having long radiation lifetime (~ 10 ms) can effectively accumulate population inversion under CW fiber laser excitation. Utilization of acousto-optic (AO) modulators in the cavity of Ho:YAG (Er:YAG) laser will enable effective Q-Switching with repetition rate easily reaching the resonance frequency of a QTF. It is expected that utilization of Ho:YAG (Er

  5. All passive architecture for high efficiency cascaded Raman conversion

    Science.gov (United States)

    Balaswamy, V.; Arun, S.; Chayran, G.; Supradeepa, V. R.

    2018-02-01

    Cascaded Raman fiber lasers have offered a convenient method to obtain scalable, high-power sources at various wavelength regions inaccessible with rare-earth doped fiber lasers. A limitation previously was the reduced efficiency of these lasers. Recently, new architectures have been proposed to enhance efficiency, but this came at the cost of enhanced complexity, requiring an additional low-power, cascaded Raman laser. In this work, we overcome this with a new, all-passive architecture for high-efficiency cascaded Raman conversion. We demonstrate our architecture with a fifth-order cascaded Raman converter from 1117nm to 1480nm with output power of ~64W and efficiency of 60%.

  6. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  7. Application of laser-induced breakdown spectroscopy in carbon ...

    Indian Academy of Sciences (India)

    2014-07-18

    Jul 18, 2014 ... We propose the use of laser-induced breakdown spectroscopy (LIBS) analytical technique to detect carbon dioxide leaks to aid in the successful application of CCS. LIBS has a real-time ... This work details the laboratory scale experiments to measure carbon contents in soil, aqueous, and air samples.

  8. High efficiency solar cells for laser power beaming applications

    Science.gov (United States)

    Jain, Raj K.; Landis, G. A.

    1995-01-01

    Understanding solar cell response to pulsed laser outputs is important for the evaluation of power beaming applications. The time response of high efficiency GaAs and silicon solar cells to a 25 nS monochromatic pulse input is described. The PC-1D computer code is used to analyze the cell current during and after the pulse for various conditions.

  9. Laser-induced breakdown spectroscopy theory and applications

    CERN Document Server

    Perini, Umberto

    2014-01-01

    This book deals with the Laser-Induced Breakdown Spectroscopy (LIBS), a widely used atomic emission spectroscopy technique for elemental analysis of materials. It is based on the use of a high-power, short pulse laser excitation. The book is divided into two main sections: the first one concerning theoretical aspects of the technique, the second one describing the state of the art in applications of the technique in different scientific/technological areas. Numerous examples of state of the art applications provide the readers an almost complete scenario of the LIBS technique. The LIBS theoretical aspects are reviewed. The book helps the readers who are less familiar with the technique to understand the basic principles. Numerous examples of state of the art applications give an almost complete scenario of the LIBS technique potentiality. These examples of applications may have a strong impact on future industrial utilization. The authors made important contributions to the development of this field.

  10. Design and optimisation of a pulsed CO2 laser for laser ultrasonic applications

    CSIR Research Space (South Africa)

    Forbes, A

    2006-07-01

    Full Text Available at the material surface is detected and converted into a defect map across the aircraft. The design and optimization of a laser system for this application, together with the basic science involved, is reviewed in this paper. This includes the optimization...

  11. Monolithic Highly Stable Yb-Doped Femtosecond Fiber Lasers for Applications in Practical Biophotonics

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2012-01-01

    Operational and environmental stability of ultrafast laser systems is critical for their applications in practical biophotonics. Mode-locked fiber lasers show great promise in applications such as supercontinuum sources or multiphoton microscopy systems. Recently, substantial progress has been made...

  12. Review of selective laser melting: Materials and applications

    Science.gov (United States)

    Yap, C. Y.; Chua, C. K.; Dong, Z. L.; Liu, Z. H.; Zhang, D. Q.; Loh, L. E.; Sing, S. L.

    2015-12-01

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  13. Review of selective laser melting: Materials and applications

    Energy Technology Data Exchange (ETDEWEB)

    Yap, C. Y., E-mail: cyap001@e.ntu.edu.sg [Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N3.1 - B2c - 01, Singapore 639798 (Singapore); Energy Research Institute @ NTU, Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Block S2 - B3a - 01, Singapore 639798 (Singapore); Chua, C. K., E-mail: mckchua@ntu.edu.sg; Liu, Z. H., E-mail: azhliu@ntu.edu.sg; Zhang, D. Q., E-mail: zhangdq@ntu.edu.sg; Loh, L. E., E-mail: leloh1@e.ntu.edu.sg; Sing, S. L., E-mail: sing0011@e.ntu.edu.sg [Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N3.1 - B2c - 01, Singapore 639798 (Singapore); Dong, Z. L., E-mail: zldong@ntu.edu.sg [School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N4.1, Singapore 639798 (Singapore)

    2015-12-15

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  14. Ultraprecise medical applications with ultrafast lasers: corneal surgery with femtosecond lasers

    Science.gov (United States)

    Loesel, Frieder H.; Kurtz, Ron M.; Horvath, Christopher; Sayegh, Samir I.; Mourou, Gerard A.; Bille, Josef F.; Juhasz, Tibor

    1999-02-01

    We investigated refractive corneal surgery in vivo and in vitro by intrastromal photodisruption using a compact ultrafast femtosecond laser system. Ultrashort-pulsed lasers operating in the femtosecond time regime are associated with significantly smaller and deterministic threshold energies for photodisruption, as well as reduced shock waves and smaller cavitation bubbles than the nanosecond or picosecond lasers. Our reliable all-solid-state laser system was specifically designed for real world medical applications. By scanning the 5 micron focus spot of the laser below the corneal surface, the overlapping small ablation volumes of single pulses resulted in contiguous tissue cutting and vaporization. Pulse energies were typically in the order of a few microjoules. Combination of different scanning patterns enabled us to perform corneal flap cutting, femtosecond-LASIK, and femtosecond intrastromal keratectomy in porcine, rabbit, and primate eyes. The cuts proved to be highly precise and possessed superior dissection and surface quality. Preliminary studies show consistent refractive changes in the in vivo studies. We conclude that the technology is capable to perform a variety of corneal refractive procedures at high precision, offering advantages over current mechanical and laser devices and enabling entirely new approaches for refractive surgery.

  15. Application of fluorescent microscopy and cascade filtration methods for analysis of soil microbial community

    Science.gov (United States)

    Ivanov, Konstantin; Pinchuk, Irina; Gorodnichev, Roman; Polyanskaya, Lubov

    2016-04-01

    Methods establishment of soil microbial cells size estimation called from the importance of current needs of research in microbial ecology. Some of the methods need to be improved for more detailed view of changes happen in microbiome of terrestrial ecosystems. The combination of traditional microscopy methods, fluorescence and filtration in addition to cutting-edge DNA analysis gives a wide range of the approaches for soil microbial ecologists in their research questions. In the most of the cases the bacterial cells size is limited of the natural conditions such as lack of nutrients or stress factors due to heterogeneity of soil system. In the samples of soils, lakes and rivers sediments, snow and rain water the bacterial cells were detected minimally of 0.2 microns. We established the combination of the cascade filtration and fluorescent microscopy for complex analysis of different terrestrial ecosystems and various soil types. Our modification based on the use of successively filtered soil suspension for collection of microbes by the membrane pores decrease. Combination with fluorescence microscopy and DNA analysis via FISH method gave the presentation of microbial interactions and review of ecological strategies of soil microorganisms. Humus horizons of primitive arctic soil were the most favorable for bacterial growth. Quantified biomass of soil bacteria depends on the dominance of cells with specific dimensions caused of stress factors. The average bacterial size of different soil varied from 0.23 to 0.38 microns, however in humus horizons of arctic soil we detected the contrast dominance of the bigger bacterial cells sized of 1.85 microns. Fungi in this case contributed to increase the availability of organic matter for bacteria because the fungal mycelium forms the appreciable part of microbial biomass of primitive arctic soil. The dominant content of bigger bacterial cells in forest and fallow soil as well as the opposite situation in arable soils caused

  16. Applications of laser ranging to ocean, ice, and land topography

    Science.gov (United States)

    Degnan, John J.

    1991-01-01

    The current status and some future applications of satellite laser ranging (SLR) are briefly reviewed. The demonstrated subcentimeter precision of ground-based SLR systems is attracting new users, particularly, in the area of high-resolution ocean, ice, and land topography. Future airborne or spaceborne SLR system will not only provide topographic data with a horizontal and vertical resolution never achieved previously, but, in addition, ground-based SLR systems, via precise tracking of spaceborne microwave and laser altimeters, will permit the expression of the topographic surface in a common geocentric reference frame.

  17. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8μm

    KAUST Repository

    Sajid, M.B.

    2015-04-01

    The mid-infrared wavelength region near 8 mu m contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the v(4) band of methane and the v(4)+v(5) band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm(-1)) and P23 (1275.5 cm(-1)) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane. (C) 2015 Elsevier Ltd. All rights reserved.

  18. Ultra high brightness laser diode arrays for pumping of compact solid state lasers and direct applications

    Science.gov (United States)

    Kohl, Andreas; Fillardet, Thierry; Laugustin, Arnaud; Rabot, Olivier

    2012-10-01

    High Power Laser Diodes (HPLD) are increasingly used in different fields of applications such as Industry, Medicine and Defense. Our significant improvements of performances (especially in power and efficiency) and a reproducible manufacturing process have led to reliable, highly robust components. For defense and security applications these devices are used predominantly for pumping of solid state lasers (ranging, designation, countermeasures, and sensors). Due to the drastically falling price per watt they are more and more replacing flash lamps as pump sources. By collimating the laser beam even with a bar to bar pitch of only 400μm. cutting edge brightness of our stacks.is achieved Due the extremely high brightness and high power density these stacks are an enabling technology for the development of compact highly efficient portable solid state lasers for applications as telemeters and designators on small platforms such as small UAVs and handheld devices. In combination with beam homogenizing optics their compact size and high efficiency makes these devices perfectly suited as illuminators for portable active imaging systems. For gated active imaging systems a very short pulse at high PRF operation is required. For this application we have developed a diode driver board with an efficiency several times higher than that of a standard driver. As a consequence this laser source has very low power consumption and low waste heat dissipation. In combination with its compact size and the integrated beam homogenizing optics it is therefore ideally suited for use in portable gated active imaging systems. The kWatt peak power enables a range of several hundred meters. The devices described in this paper mostly operate at wavelength between 800 nm and 980nm. Results from diodes operating between 1300 nm and 1550 nm are presented as well.

  19. Laser-induced stress transients: applications for molecular delivery

    Science.gov (United States)

    Flotte, Thomas J.; Lee, Shun; Zhang, Hong; McAuliffe, Daniel J.; Douki, Tina; Doukas, Apostolos G.

    1995-05-01

    Lasers can be used to enhance the delivery of a number of molecules. Other investigators have demonstrated local release of molecules from liposomes following laser irradiation, microbeam disruption of the cell membrane to increase cell transport, microbeam ablation of the zona pellucida surrounding the ovum to increase the chances of fertilization, and increased transcutaneous transport following ablation of the stratum corneum. Our experiments have shown that laser-induced stress transients can be utilized as a vector for intracellular delivery of molecules that may or may not normally cross the cell membrane. These two conditions have been tested with Photofrin and DNA. This technology may have applications in cell and molecular biology, cancer therapy, gene therapy, and others.

  20. Medical and biological applications for ultrafast laser pulses

    Science.gov (United States)

    Lubatschowski, Holger; Heisterkamp, Alexander; Will, Fabian; Singh, Ajoy I.; Serbin, Jesper; Ostendorf, Andreas; Kermani, Omid; Heermann, R.; Welling, Herbert; Ertmer, Wolfgang

    2003-02-01

    Due to the low energy threshold of photodisruption with fs laser pulses, thermal and mechanical side effects are limited to the sub μm range. The neglection of side effects enables the use of ultrashort laser pulses in a broad field of medical applications. Moreover, the interaction process based on nonlinear absorption offers the opportunity to process transparent tissue three dimensionally inside the bulk. We demonstrate the feasibility of surgical procedures in different fields of medical interest: In ophthalmology intrastromal cutting and preparing of corneal flaps for refractive surgery in living animals is presented. Besides, the very low mechanical side effects enables the use of fs-laser in otoralyngology to treat ocecular bones. Moreover, the precise cutting quality can be used in fields of cardiovascular surgery for the treatment of arteriosclerosis as well as in dentistry to remove caries from dental hard tissue.

  1. Expenditure Cascades

    OpenAIRE

    Frank, R; Levine, A.; Dijk, O.

    2014-01-01

    Prevailing economic models of consumer behavior completely ignore the well-documented link between context and evaluation. We propose and test a theory that explicitly incorporates this link. Changes in one group's spending shift the frame of reference that defines consumption standards for others just below them on the income scale, giving rise to expenditure cascades. Our model, a descendant of James Duesenberry's relative income hypothesis, predicts the observed ways in which individual sa...

  2. Types of Lasers and Their Applications in Pediatric Dentistry.

    Science.gov (United States)

    Nazemisalman, Bahareh; Farsadeghi, Mahya; Sokhansanj, Mehdi

    2015-01-01

    Laser technology has been recently introduced into the dental field with the idea to replace drilling. Having a less painful first dental experience by the use of modern instruments like laser can be an efficient preventive and therapeutic strategy in pediatric dentistry. Pedodontists need to learn the new less invasive technologies and adopt them in their routine practice. This study aimed to review the available types of lasers and their applications in pediatric dentistry. An electronic search was carried out in IranMedex, InterScience, Scopus, Science Direct, PubMed, ProQuest, Medline and Google Scholar databases to find relevant articles published from 2000 to 2014. Relevant textbooks were reviewed as well. Laser can be used as a suitable alternative to many conventional diagnostic and therapeutic dental procedures. It is especially efficient for caries detection and removal, pulp therapy, lowering the risk of infection, inflammation and swelling and reducing bleeding. On the other hand, due to minimal invasion, laser treatment is well tolerated by children. Improved patient cooperation leads to higher satisfaction of the parents, dentists and the children themselves.

  3. Types of Lasers and Their Applications in Pediatric Dentistry

    Science.gov (United States)

    Nazemisalman, Bahareh; Farsadeghi, Mahya; Sokhansanj, Mehdi

    2015-01-01

    Laser technology has been recently introduced into the dental field with the idea to replace drilling. Having a less painful first dental experience by the use of modern instruments like laser can be an efficient preventive and therapeutic strategy in pediatric dentistry. Pedodontists need to learn the new less invasive technologies and adopt them in their routine practice. This study aimed to review the available types of lasers and their applications in pediatric dentistry. An electronic search was carried out in IranMedex, InterScience, Scopus, Science Direct, PubMed, ProQuest, Medline and Google Scholar databases to find relevant articles published from 2000 to 2014. Relevant textbooks were reviewed as well. Laser can be used as a suitable alternative to many conventional diagnostic and therapeutic dental procedures. It is especially efficient for caries detection and removal, pulp therapy, lowering the risk of infection, inflammation and swelling and reducing bleeding. On the other hand, due to minimal invasion, laser treatment is well tolerated by children. Improved patient cooperation leads to higher satisfaction of the parents, dentists and the children themselves. PMID:26464775

  4. Laser Pyrolysis Techniques: Application To Catalysis, Combustion Diagnostics, And Kinetics

    Science.gov (United States)

    Smith, Gregory P.

    1984-05-01

    A pulsed laser pyrolysis method has been developed to study kinetic processes at high temperatures. A CO2 laser is used to irradiate a 100 torr mixture of an infrared absorber (SF6), bath gas (N2), and reactants. Rapid heating to 700-1400 K occurs, followed by two-stage cooling. Unimolecular reactions are studied by competitive kinetics with a known standard, using mass-spectrometric or gas-chromatographic analysis. Bimolecular processes are examined using laser-induced fluorescence (LIF). The technique offers great advantages in reaching reactive temperatures in a fast and time-resolved manner, without the complications of hot surfaces. It is thus an ideal tool for analyzing and measuring some of the basic processes occurring in more complicated, real, hot systems. Our recent applications of the laser pyrolysis method in the areas of catalysis and combustion are summarized here. Several transition metal-carbonyl bond dissociation energies have been measured, and catalysis by the hot metal particulate products was observed. Since the use of LIF as a flame diagnotic requires some knowledge of the fluorescence quenching rates at high temperatures, the laser pyrolysis method was used to measure these rates for the important OH radical. Its reaction rate with acetylene was also measured, with implications for flame modeling and the mechanism of soot formation. Finally, this method can be used to ignite low concentrations of fuel and oxidant, and then study the time-resolved evolution of the flame chemistry by LIF and chemiluminescence observations.

  5. Laser-launched flyer plate and confined laser ablation for shock wave loading: validation and applications.

    Science.gov (United States)

    Paisley, Dennis L; Luo, Sheng-Nian; Greenfield, Scott R; Koskelo, Aaron C

    2008-02-01

    We present validation and some applications of two laser-driven shock wave loading techniques: laser-launched flyer plate and confined laser ablation. We characterize the flyer plate during flight and the dynamically loaded target with temporally and spatially resolved diagnostics. With transient imaging displacement interferometry, we demonstrate that the planarity (bow and tilt) of the loading induced by a spatially shaped laser pulse is within 2-7 mrad (with an average of 4+/-1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible, in particular, when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation allows for flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These techniques can be utilized to investigate such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples.

  6. Diode-pumped all-solid-state lasers and applications

    CERN Document Server

    Parsons-Karavassilis, D

    2002-01-01

    This thesis describes research carried out by the within the Physics Department at Imperial College that was aimed at developing novel all-solid-state laser sources and investigating potential applications of this technology. A description of the development, characterisation and application of a microjoule energy level, diode-pumped all-solid-state Cr:LiSGAF femtosecond oscillator and regenerative amplifier system is presented. The femtosecond oscillator was pumped by two commercially available laser diodes and produced an approx 80 MHz pulse train of variable pulse duration with approx 30 mW average output power and a tuning range of over approx 60 nm. This laser oscillator was used to seed a regenerative amplifier, resulting in adjustable repetition rate (single pulse to 20 kHz) approx 1 mu J picosecond pulses. These pulses were compressed to approx 150 fs using a double-pass twin-grating compressor. The amplifier's performance was investigated with respect to two different laser crystals and different pul...

  7. Coupling simultaneous dissolved nitrate measurements with quantum cascade laser based nitrous oxide flux and isotopocule analysis to investigate the biogeochemical processes occurring in a denitrifying bioreactor.

    Science.gov (United States)

    Williams, D. J.; Maxwell, B.; Deshmukh, P.; Chen, H.

    2016-12-01

    Denitrifying bioreactors are used to treat nitrogen enriched water from agricultural operations. These systems may also be an important source of nitrous oxide emissions, a potent greenhouse gas. Bioreactors also provide researchers with an opportunity to investigate the biogeochemical processes occurring in soils under controlled conditions. A pilot-scale bioreactor with woodchip media was injected with KNO3 at a constant flow rate through the system. The water-filled-pore-space (WFPS) was varied in separate experiments to create differing aerobic conditions. A quantum cascade laser spectroscopy system was used to determine the flux and isotopic signature of N2O emissions from woodchip bioreactor media over time. Simultaneous nitrate concentration measurements were made using an optical method at multiple points in the bioreactor. Isotopic site-preference (SP) characterization of N2O emissions was used to estimate production sources from soil nitrification and denitrification. A dynamic gas sampling method was used to measure N2O mixing ratios, which required ambient air to equalize chamber atmospheric pressure during sampling. Precise instrument calibration using gas samples of known isotopic abundances, provided by the Swiss Federal Labs (EMPA), together with a Keeling plot method to account for variations in isotopocule composition in ambient air, produced reliable SP estimates. Initial experiments during 100% WFPS show that SP and δ15Nbulk values were varied from -6‰ to 3‰ and -23‰ to -12‰, respectively. The trend of these values indicated that the N2O source was slightly changed from partial nitrification to denitrification during the measuring period of time. The peak rate of nitrous oxide production occurred 7 hours after peak nitrate removal. These results and others to be presented show the utility of coupling real-time dissolved and gas phase measurements for studying nitrogen cycling in soils.

  8. Continuous and unattended measurements of the site preference of nitrous oxide emitted from an agricultural soil using quantum cascade laser spectrometry with intercomparison with isotope ratio mass spectrometry.

    Science.gov (United States)

    Yamamoto, Akinori; Uchida, Yoshitaka; Akiyama, Hiroko; Nakajima, Yasuhiro

    2014-07-15

    The difference between the (15)N natural abundance of (14)N-(15)N-O and (15)N-(14)N-O (site preference; SP) is used to understand the mechanisms underlying N2O emissions from soils. We investigated the use of quantum cascade laser (QCL) absorption spectrometry for continuous and precise analysis of the SP of N2O emitted from a field soil at atmospheric mixing ratios. A QCL-based spectrometer was used to determine the SP of soil-emitted N2O accumulated in a closed chamber system without preconcentration. N2O standards (gas samples. Intercomparison measurements of QCLS and isotope ratio mass spectrometry (IRMS) were performed on N2O calibration gases at different mixing ratios. The observed dependency of the QCLS result on the N2O mixing ratio was corrected. Measurement of SP of N2O emitted from the field suggested that the SP of N2O varied from 0 to 40‰ over a period of 1 month. The precisions of the SP measurements (300-2500 ppbv) were control precision of ±0.01 K. Continuous and unattended measurements of the SP of N2O emitted from soils were achieved at low N2O mixing ratios. The accuracy of the QCLS measurements for the SP of N2O was significantly improved by precisely controlling the temperature of the system and by correcting for the concentration dependency of the raw data through an intercomparison with IRMS measurements. Copyright © 2014 John Wiley & Sons, Ltd.

  9. MATLAB-based program for optimization of quantum cascade laser active region parameters and calculation of output characteristics in magnetic field

    Science.gov (United States)

    Smiljanić, J.; Žeželj, M.; Milanović, V.; Radovanović, J.; Stanković, I.

    2014-03-01

    A strong magnetic field applied along the growth direction of a quantum cascade laser (QCL) active region gives rise to a spectrum of discrete energy states, the Landau levels. By combining quantum engineering of a QCL with a static magnetic field, we can selectively inhibit/enhance non-radiative electron relaxation process between the relevant Landau levels of a triple quantum well and realize a tunable surface emitting device. An efficient numerical algorithm implementation is presented of optimization of GaAs/AlGaAs QCL region parameters and calculation of output properties in the magnetic field. Both theoretical analysis and MATLAB implementation are given for LO-phonon and interface roughness scattering mechanisms on the operation of QCL. At elevated temperatures, electrons in the relevant laser states absorb/emit more LO-phonons which results in reduction of the optical gain. The decrease in the optical gain is moderated by the occurrence of interface roughness scattering, which remains unchanged with increasing temperature. Using the calculated scattering rates as input data, rate equations can be solved and population inversion and the optical gain obtained. Incorporation of the interface roughness scattering mechanism into the model did not create new resonant peaks of the optical gain. However, it resulted in shifting the existing peaks positions and overall reduction of the optical gain. Catalogue identifier: AERL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERL_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 37763 No. of bytes in distributed program, including test data, etc.: 2757956 Distribution format: tar.gz Programming language: MATLAB. Computer: Any capable of running MATLAB version R2010a or higher. Operating system: Any platform

  10. Laser assisted die bending: a new application of high power diode lasers

    Science.gov (United States)

    Schuöcker, D.; Schumi, T.; Spitzer, O.; Bammer, F.; Schuöcker, G.; Sperrer, G.

    2015-02-01

    Nowadays high power lasers are mainly used for cutting of sheet metals, for welding, hardening and rapid prototyping. In the forming of sheet metals as bending or deep drawing lasers are not used. Nevertheless a few years ago a new application of high power lasers has been invented, where bending of materials that break at room temperature becomes possible by heating them along the bending edge with high power lasers thus allowing their treatment without cracks and rupture. For this purpose a large number of diode lasers are arranged in the bottom tool of a bending machine (a V-shaped die) which heat up the initially flat sheet metal during the bending process what is performed by pressing it into the die with a knife shaped upper tool where due to the laser heating the material is softened and thus cracks are avoided. For the technical realization of the new process of laser assisted die bending, modules equipped with numerous laser diodes and a total beam power of 2,5 kW are used. The light emitted by these modules enters a tool with a length of 15cm and is deflected towards the workpiece. By using ten of these modules with adjacent dies and by integrating those in a bending press a bending edge of sheet metals with a length of 1500mm can be realized. Such a bending press with laser assistance also needs energization with a power of practically 50kW, a respective water flow, a heat exchanger system and also a control for all functions of this system. Special measures have also been developed to avoid radiating of those tools that are not covered by a workpiece in the case of bending edges shorter than the full length of the bending tools whereas individual short circuiting of diode modules can be performed. Specific measures to ensure a safe operation without any harm to the operational person have been realized. Exploitation of the bending process has been carried out for titanium, where material thicknesses up to 3mm have been bent successfully.

  11. Novel oral applications of ultra-short laser pulses

    Science.gov (United States)

    Wieger, V.; Wernisch, J.; Wintner, E.

    2007-02-01

    In the past decades, many efforts have been made to replace mechanical tools in oral applications by various laser systems. The reasons therefore are manifold: i) Friction causes high temperatures damaging adjacent tissue. ii) Smear layers and rough surfaces are produced. iii) Size and shape of traditional tools are often unsuitable for geometrically complicated incisions and for minimum invasive treatment. iv) Mechanical damage of the remaining tissue occurs. v) Online diagnosis for feedback is not available. Different laser systems in the µs and sub-&mrgs-pulse regime, among them Erbium lasers, have been tested in the hope to overcome the mentioned drawbacks and, to some extent, they represent the current state of the art with respect to commercial and hence practical application. In the present work the applicability of scanned ultrashort pulse lasers (USPLs) for biological hard tissue as well as dental restoration material removal was tested. It is shown that cavities with features superior to mechanically treated or Erbium laser ablated cavities can be generated if appropriate scan algorithms and optimum laser parameters are matched. Smooth cavity rims, no microcracks, melting or carbonisation and precise geometry are the advantages of scanned USLP ablation. For bone treatment better healing conditions are expected as the natural structure remains unaffected by the preparation procedure. The novelty of this work is represented by a comprehensive compilation of various experimental results intended to assess the performance of USPLs. In this context, various pulse durations in the picosecond and femtosecond regime were applied to dental and bone tissue as well as dental restoration materials which is considered to be indispensable for a complete assessment. Parameters like ablation rates describing the efficiency of the ablation process, and ablation thresholds were determined - some of them for the first time - and compared to the corresponding Erbium

  12. Applications of laser-induced gratings to spectroscopy and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

  13. Borate Crystals for Nonlinear Optical and Laser Applications: A Review

    Directory of Open Access Journals (Sweden)

    R. Arun Kumar

    2013-01-01

    Full Text Available The development of borate-based single crystals for laser and frequency conversion applications is reviewed. The basic idea behind nonlinear optics and the role of anionic groups in the borate crystals are summarized. The properties of borate crystals—BBO, LBO, CBO, KBBF, SBBO, CLBO, YCOB, GdCOB, GdYCOB, KAB and LCB—are discussed. The growth and characterization of several rare earth-based borate crystals are mainly focused. Several borate crystals are grown from the melt techniques and a few crystals are grown adopting the flux technique. Many rare earth-based borate crystals are extensively used in device applications as they exhibit the frequency conversion ability along with high laser-induced damage tolerance.

  14. Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry

    Science.gov (United States)

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Ajlal, Syed

    2016-01-01

    Light amplification by stimulated emission of radiation (laser) has been used widely in a range of biomedical and dental applications in recent years. In the field of restorative dentistry, various kinds of lasers have been developed for diagnostic (e.g. caries detection) and operative applications (e.g. tooth ablation, cavity preparation, restorations, bleaching). The main benefits for laser applications are patient comfort, pain relief and better results for specific applications. Major concerns for using dental lasers frequently are high cost, need for specialized training and sensitivity of the technique, thereby compromising its usefulness particularly in developing countries. The main aim of this paper is to evaluate and summarize the applications of lasers in restorative dentistry, including a comparison of the applications of lasers for major restorative dental procedures and conventional clinical approaches. A remarkable increase in the use of lasers for dental application is expected in the near future. PMID:26642047

  15. Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry.

    Science.gov (United States)

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Ajlal, Syed

    2016-01-01

    Light amplification by stimulated emission of radiation (laser) has been used widely in a range of biomedical and dental applications in recent years. In the field of restorative dentistry, various kinds of lasers have been developed for diagnostic (e.g. caries detection) and operative applications (e.g. tooth ablation, cavity preparation, restorations, bleaching). The main benefits for laser applications are patient comfort, pain relief and better results for specific applications. Major concerns for using dental lasers frequently are high cost, need for specialized training and sensitivity of the technique, thereby compromising its usefulness particularly in developing countries. The main aim of this paper is to evaluate and summarize the applications of lasers in restorative dentistry, including a comparison of the applications of lasers for major restorative dental procedures and conventional clinical approaches. A remarkable increase in the use of lasers for dental application is expected in the near future. © 2015 S. Karger AG, Basel.

  16. Solvent-free fluidic organic dye lasers.

    Science.gov (United States)

    Choi, Eun Young; Mager, Loic; Cham, Tran Thi; Dorkenoo, Kokou D; Fort, Alain; Wu, Jeong Weon; Barsella, Alberto; Ribierre, Jean-Charles

    2013-05-06

    We report on the demonstration of liquid organic dye lasers based on 9-(2-ethylhexyl)carbazole (EHCz), so-called liquid carbazole, doped with green- and red-emitting laser dyes. Both waveguide and Fabry-Perot type microcavity fluidic organic dye lasers were prepared by capillary action under solvent-free conditions. Cascade Förster-type energy transfer processes from liquid carbazole to laser dyes were employed to achieve color-variable amplified spontaneous emission and lasing. Overall, this study provides the first step towards the development of solvent-free fluidic organic semiconducting lasers and demonstrates a new kind of optoelectronic applications for liquid organic semiconductors.

  17. Ultra-stable clock laser system development towards space applications.

    Science.gov (United States)

    Świerad, Dariusz; Häfner, Sebastian; Vogt, Stefan; Venon, Bertrand; Holleville, David; Bize, Sébastien; Kulosa, André; Bode, Sebastian; Singh, Yeshpal; Bongs, Kai; Rasel, Ernst Maria; Lodewyck, Jérôme; Le Targat, Rodolphe; Lisdat, Christian; Sterr, Uwe

    2016-09-26

    The increasing performance of optical lattice clocks has made them attractive for scientific applications in space and thus has pushed the development of their components including the interrogation lasers of the clock transitions towards being suitable for space, which amongst others requires making them more power efficient, radiation hardened, smaller, lighter as well as more mechanically stable. Here we present the development towards a space-compatible interrogation laser system for a strontium lattice clock constructed within the Space Optical Clock (SOC2) project where we have concentrated on mechanical rigidity and size. The laser reaches a fractional frequency instability of 7.9 × 10-16 at 300 ms averaging time. The laser system uses a single extended cavity diode laser that gives enough power for interrogating the atoms, frequency comparison by a frequency comb and diagnostics. It includes fibre link stabilisation to the atomic package and to the comb. The optics module containing the laser has dimensions 60 × 45 × 8 cm3; and the ultra-stable reference cavity used for frequency stabilisation with its vacuum system takes 30 × 30 × 30 cm3. The acceleration sensitivities in three orthogonal directions of the cavity are 3.6 × 10-10/g, 5.8 × 10-10/g and 3.1 × 10-10/g, where g ≈ 9.8 m/s2 is the standard gravitational acceleration.

  18. Modeling laser pulse evolution in ionizing gas and plasma with application to laser wakefield acceleration

    Science.gov (United States)

    Cooley, James Hamilton

    The interaction of high intensity laser pulses with matter is of current research interest not only for potential applications but also due to the interesting non-linear process that can occur with current experimental facilities. Understanding many of the non-linear processes requires significant modeling and simulation effort. We explore several aspects of laser pulse evolution and plasma response in simulations ranging from modeling laser wakefield accelerators to modeling basic ionization processes. First, we present a model that describes the onset and growth of axial modulation found experimentally during the formation of plasma channels formed using an axicon lens. We provide a systematic development that describes this new type of parametric instability and explains the pressure dependence and the mechanism for formation of these axial modulations in the channel. Next, we describe details of a new three-dimensional laser pulse evolution code that we have developed to model propagation in tenuous gas and plasma and we provide relevant information about the validation and testing of the code. We then use this new code to examine the three-dimensional structure of the laser pulse evolving in the presence of ionizing gas. In particular we present results from the first three-dimensional study of the ionization scattering instability. Finally, we examine injecting electrons into laser wakefield accelerators. We examine in detail the injection and trapping characteristics for an electron beam with an initially broad energy distribution and look at the effect of beam loading on the trapping efficiency. We present estimates for the maximum charge that can be trapped from a low energy beam with a Boltzmann type energy distribution.

  19. Applications of laser wakefield accelerators for biomedical imaging

    Science.gov (United States)

    Najmudin, Zulfikar

    2014-10-01

    Laser-wakefield accelerators driven by high-intensity short-pulse lasers are a proven compact source of high-energy electron beams, with energy gains of ~GeV energy in centimetres of plasma demonstrated. One of the main proposed applications for these accelerators is to drive synchrotron light sources, in particular for x-ray applications. It has also been shown that the same plasma accelerator can also act as a wigglers, capable of the production of high brightness and spatially coherent hard x-ray beams. In this latest work, we demonstrate the application of these unique light-sources for biological and medical applications. The experiments were performed with the Astra Gemini laser at the Rutherford Appleton Laboratory in the UK. Gemini produces laser pulses with energy exceeding 10 J in pulse lengths down to 40 fs. A long focal length parabola (f / 20) is used to focus the laser down to a spot of size approximately 25 μ m (fwhm) into a gas-cell of variable length. Electrons are accelerated to energies up to 1 GeV and a bright beam of x-rays is observed simultaneously with the accelerated beam. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was then used for imaging a number of interesting medical and biological samples. Full tomographic imaging of a human trabecular bone sample was made with resolution easily exceeding the ~100 μm level required for CT applications. Phase-contrast imaging of human prostrate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. They also show that full 3D imaging can be made possible with this source in a fraction of the time that it would take with a corresponding x-ray tube. The JAI is funded by STFC Grant ST/J002062/1.

  20. Bosonic cascades of indirect excitons

    Science.gov (United States)

    Nalitov, A. V.; De Liberato, S.; Lagoudakis, P.; Savvidis, P. G.; Kavokin, A. V.

    2017-08-01

    Recently, the concept of the terahertz bosonic cascade laser (BCL) based on a parabolic quantum well (PQW) embedded in a microcavity was proposed. We refine this proposal by suggesting transitions between indirect exciton (IX) states as a source of terahertz emission. We explicitly propose a structure containing a narrow-square QW and a wide-parabolic QW for the realisation of a bosonic cascade. Advantages of this type of structures are in large dipole matrix elements for terahertz transitions and in long exciton radiative lifetimes which are crucial for realisation of threshold and quantum efficiency BCLs.