Sample records for high-power pulsed lasers

  1. High power ultrashort pulse lasers

    Energy Technology Data Exchange (ETDEWEB)

    Perry, M.D.


    Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced.

  2. High power, short pulses ultraviolet laser for the development of a new x-ray laser

    Energy Technology Data Exchange (ETDEWEB)

    Meixler, L.; Nam, C.H.; Robinson, J.; Tighe, W.; Krushelnick, K.; Suckewer, S.; Goldhar, J.; Seely, J.; Feldman, U.


    A high power, short pulse ultraviolet laser system (Powerful Picosecond-Laser) has been developed at the Princeton Plasma Physics Laboratory (PPPL) as part of experiments designed to generate shorter wavelength x-ray lasers. With the addition of pulse compression and a final KrF amplifier the laser output is expected to have reached 1/3-1/2 TW (10/sup 12/ watts) levels. The laser system, particularly the final amplifier, is described along with some initial soft x-ray spectra from laser-target experiments. The front end of the PP-Laser provides an output of 20--30 GW (10/sup 9/ watts) and can be focussed to intensities of /approximately/10/sup 16/ W/cm/sup 2/. Experiments using this output to examine the effects of a prepulse on laser-target interaction are described. 19 refs., 14 figs.

  3. An ultra short pulse reconstruction software applied to the GEMINI high power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Galletti, Mario, E-mail: [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Galimberti, Marco [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Hooker, Chris [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); University of Oxford, Oxford (United Kingdom); Chekhlov, Oleg; Tang, Yunxin [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Bisesto, Fabrizio Giuseppe [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Curcio, Alessandro [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Sapienza – University of Rome, P.le Aldo Moro, 2, 00185 Rome (Italy); Anania, Maria Pia [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Giulietti, Danilo [Physics Department of the University and INFN, Pisa (Italy)


    The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class. - Highlights: • Integration of the diagnostic tool on high power laser. • Validation of the GROG algorithm in comparison to a well-known commercial available software. • Complete characterization of the GEMINI ultra-short high power laser pulse.

  4. High power double-scale pulses from a gain-guided double-clad fiber laser (United States)

    Zhang, Haitao; Gao, Gan; Li, Qinghua; Gong, Mali


    Generation of high power double-scale pulses from a gain-guided double-clad fiber laser is experimentally demonstrated. By employing the Yb-doped 10/130 double-clad fiber as the gain medium, the laser realizes an output power of 5.1 W and pulse energy of 0.175 µJ at repetition rate of 29.14 MHz. To the best of our knowledge, this average output power is the highest among the reported double-scale pulse oscillators. The autocorrelation trace of pulses contains the short (98 fs) and long (29.5 ps) components, and the spectral bandwidth of the pulse is 27.3 nm. Such double-scale pulses are well suited for seeding the high power MOPA (master oscillator power amplifier) systems, nonlinear frequency conversion and optical coherence tomography.

  5. High power laser pulse circulation experiment for compact quasi-monochromatic tunable X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Meng, De [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan)]. E-mail:; Sakamoto, Fumito [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Yamamoto, Tomohiko [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Dobashi, Katsuhiro [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Uesaka, Mitsuru [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Nose, Hiroyuki [Ishikawajima-Harima Heavy Industries Co., Ltd., Toyosu Ihi Building, 1-1, Toyosu 3-chome, Koto-ku, Tokyo 135-8710 (Japan); Ishida, Daisuke [Ishikawajima-Harima Heavy Industries Co., Ltd., Toyosu Ihi Building, 1-1, Toyosu 3-chome, Koto-ku, Tokyo 135-8710 (Japan); Kaneko, Namio [Ishikawajima-Harima Heavy Industries Co., Ltd., Toyosu Ihi Building, 1-1, Toyosu 3-chome, Koto-ku, Tokyo 135-8710 (Japan); Sakai, Yasuo [Ishikawajima-Harima Heavy Industries Co., Ltd., Toyosu Ihi Building, 1-1, Toyosu 3-chome, Koto-ku, Tokyo 135-8710 (Japan)


    Laser electron Compton scattering monochromatic tunable X-ray source using X-band (11.424 GHz) electron linear accelerator and Q-switch Nd:YAG laser is under construction at Nuclear Professional School, University of Tokyo. To enhance the X-ray intensity, we installed a laser circulation system. Now, we are performing the circulation experiment by using a high power laser (1.4 J, 532 nm). We confirmed the laser pulse circulated in the optical circuit more than 15 times and the laser intensity is enhanced about 3.5 times.

  6. Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A


    Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities.

  7. Transient magnetized plasma as an optical element for high power laser pulses

    Directory of Open Access Journals (Sweden)

    Nobuhiko Nakanii


    Full Text Available Underdense plasma produced in gas jets by low intensity laser prepulses in the presence of a static magnetic field, B∼0.3  T, is shown experimentally to become an optical element allowing steering of tightly focused high power femtosecond laser pulses within several degrees along with essential enhancement of pulse’s focusability. Strong laser prepulses form a density ramp perpendicularly to magnetic field direction and, owing to the light refraction, main laser pulses propagate along the magnetic field even if it is tilted from the laser axis. Electrons generated in the laser pulse wake are well collimated and follow in the direction of the magnetic field; their characteristics are measured to be not sensitive to the tilt of magnetic field up to angles ±5°.

  8. Fiber Optic Cables for Transmission of High-Power Laser Pulses in Spaceflight Applications (United States)

    Thomes, W. J., Jr.; Ott, M. N.; Chuska, R. F.; Switzer, R. C.; Blair, D. E.


    Lasers with high peak power pulses are commonly used in spaceflight missions for a wide range of applications, from LIDAR systems to optical communications. Due to the high optical power needed, the laser has to be located on the exterior of the satellite or coupled through a series of free space optics. This presents challenges for thermal management, radiation resistance, and mechanical design. Future applications will require multiple lasers located close together, which further complicates the design. Coupling the laser energy into a fiber optic cable allows the laser to be relocated to a more favorable position on the spacecraft. Typical fiber optic termination procedures are not sufficient for injection of these high-power laser pulses without catastrophic damage to the fiber endface. In the current study, we will review the causes of fiber damage during high-power injection and discuss our new manufacturing procedures that overcome these issues to permit fiber use with high reliability in these applications. We will also discuss the proper methods for launching the laser pulses into the fiber to avoid damage and how this is being implemented for current spaceflight missions.

  9. Multi-phase ionization dynamics of carbon thin film irradiated by high power short pulse laser (United States)

    Kawahito, Daiki; Kishimoto, Yasuaki


    The ionization dynamics of a carbon thin film irradiated by a high power short pulse laser in the range of 1019-20 W/cm2 are studied using the extended particle-based integrated code (EPIC), which includes atomic and collisional processes. Two types of ionization dynamics exhibiting different spatio-temporal structures are found to predominantly regulate the process, and arise depending on the laser amplitude. The first is a fast convective propagation for charge states up to C4+, which keeps a steep ionization front. The velocity of the front is of the order of the speed of light. The front formation results from the localized longitudinal electrostatic field and associated field ionization, which in turn propagates inside the film. This convective propagation is triggered when the laser field becomes high enough that electron bunches accelerated by the laser ponderomotive force reach relativistic energies and penetrate inside the film across the surface. The second dynamics is a fast non-diffusive propagation of ionization showing a long plasma density scale length for C5+ and C6+. This process results predominantly from electron impact ionization by high energy electron bunches successively produced by the laser. These electron bunches also excite wake fields that propagate inside the film and contribute to ionizing the film to higher charge states, i.e., C5+ and C6+, especially near the front surface. The effect of field ionization loss, which sensitively influences the ionization dynamics in the relatively low laser power regime, is also discussed.

  10. High Power Vanadate lasers

    CSIR Research Space (South Africa)

    Strauss, HJ


    Full Text Available This presentation aims at the following: to develop new techniques to mount laser crystals; compare the laser properties of two equally doped, high power Nd:YVO4 and Nd: GdVO4 lasers; build a 1um vanadate laser with average output power exceeding...

  11. Towards swift ion bunch acceleration by high-power laser pulses at the Centre for Advanced Laser Applications (CALA) (United States)

    Lindner, F. H.; Haffa, D.; Bin, J. H.; Englbrecht, F.; Gao, Y.; Gebhard, J.; Hartmann, J.; Hilz, P.; Kreuzer, C.; Lehrack, S.; Ostermayr, T. M.; Rösch, T. F.; Speicher, M.; Würl, M.; Parodi, K.; Schreiber, J.; Thirolf, P. G.


    Laser-driven acceleration of ions has inspired novel applications, that can benefit from ion bunch properties different from conventionally (non-laser based) accelerated particle beams. Those differences range from extremely short bunch durations, broad energy spectra, large divergence angles and small source sizes to ultra-high ion bunch densities. So far, the main focus of research has been concentrating on the physics of the interaction of intense laser pulses with plasmas and the related mechanisms of ion acceleration. Now, the new Centre for Advanced Laser Applications (CALA) near Munich aims at pushing these ion bunches towards applications, including radiation therapy of tumors and the development of heavy ion bunches with solid-state-like density. These are needed for novel reaction mechanisms ('fission-fusion') to study the origin of heavy elements in the universe and to prepare for related studies at the upcoming EU-funded high-power laser facility ELI - Nuclear Physics in Bucharest.

  12. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers (United States)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.


    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  13. Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.


    Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.

  14. High power pulsed fiber laser development for Co2 space based dial system (United States)

    Canat, Guillaume; Le Gouët, Julien; Lombard, Laurent; Bresson, Alexandre; Goular, Didier; Dolfi-Bouteyre, Agnès.; Duzellier, Sophie; Boivin, Denis; Nilsson, Johan; Sahu, Jayata; Bordais, Sylvain


    High energy fiber lasers emitting around 1579nm is seen as a possible technology for the laser unit of a spaceborn CO2 DIAL system. We are developing an all fiber system with the following expected performances: pulse energy of 260μJ, pulse duration 150ns, beam quality M2 laser stability 200 kHz. One of our main concerns has been the radiation induced attenuation mitigation. Various fiber compositions have been investigated.

  15. Ultra-short pulse reconstruction software in high power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Galletti, M. [Physics Department of the University and INFN, Pisa (Italy); Galimberti, M. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Giulietti, D. [Physics Department of the University and INFN, Pisa (Italy)


    An ultra-short pulse reconstruction software, validated through a set of experimental measurements on the front-end of the Vulcan laser at the RAL Central Laser Facility is presented. The measurements were acquired in Target Area Petawatt of the Vulcan laser, both using a conventional autocorrelation technique and the GRENOUILLE technique in order to compare the results. The FWHM of the laser pulses considered came out to be comparable for the two techniques. In this experimental campaign for the first time a technique different from the autocorrelation one has been used for a PW class laser as Vulcan.

  16. Ultra-short pulse reconstruction software in high power laser system (United States)

    Galletti, M.; Galimberti, M.; Giulietti, D.


    An ultra-short pulse reconstruction software, validated through a set of experimental measurements on the front-end of the Vulcan laser at the RAL Central Laser Facility is presented. The measurements were acquired in Target Area Petawatt of the Vulcan laser, both using a conventional autocorrelation technique and the GRENOUILLE technique in order to compare the results. The FWHM of the laser pulses considered came out to be comparable for the two techniques. In this experimental campaign for the first time a technique different from the autocorrelation one has been used for a PW class laser as Vulcan.

  17. Forward voltage short-pulse technique for measuring high power laser array junction temperature (United States)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)


    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  18. High-power ns-pulse fiber laser sources for remote sensors (United States)

    Di Teodoro, Fabio; Belden, Paul; Ionov, Pavel; Werner, Nicolette


    The development of fiber-based laser sources for space-borne remote sensors must meet many concurrent requirements including high pulse energy/peak power, excellent beam quality, narrow spectral linewidth, simple thermal management, small volume and mass, low power consumption, rugged packaging, and long-term reliability. To address these requirements, many aspects of pulse fiber laser technology must be advanced beyond the state of the art of traditional optical sources used in telecommunications and materials processing. In this article, we discuss component and solutions that enable pulsed fiber laser sources to support remote sensing from space. We also describe several examples of such sources and characterize their performance.

  19. Advanced concepts for high-power, short-pulse CO2 laser development (United States)

    Gordon, Daniel F.; Hasson, Victor; von Bergmann, Hubertus; Chen, Yu-hsin; Schmitt-Sody, A.; Penano, Joseph R.


    Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO2) laser is capable of delivering high energy, 10 micron wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The Naval Research Laboratory and Air Force Research Laboratory are developing a novel CO2 laser designed to deliver ~1 Joule, ~1 picosecond pulses, from a compact gain volume (~2x2x80 cm). The design is based on injection seeding an unstable resonator, in order to achieve high energy extraction efficiency, and to take advantage of power broadening. The unstable resonator is seeded by a solid state front end, pumped by a custom built titanium sapphire laser matched to the CO2 laser bandwidth. In order to access a broader range of mid infrared wavelengths using CO2 lasers, one must consider nonlinear frequency multiplication, which is non-trivial due to the bandwidth of the 10 micron radiation.

  20. High-power widely tunable sub-20 fs Gaussian laser pulses for ultrafast nonlinear spectroscopy. (United States)

    Metzger, Bernd; Steinmann, Andy; Giessen, Harald


    We demonstrate the generation of widely tunable sub-20 fs Gaussian-shaped laser pulses using a grating-based 4-f pulse shaper and a liquid crystal spatial light modulator. Our pump source is an Yb:KGW solitary mode-locked oscillator at 44 MHz repetition rate which is coupled into a large mode area microstructured fiber to generate a broad spectrum from below 900 nm to above 1150 nm. These pulses are precompressed by a prism sequence and subsequently sent into the pulse shaper. We use the multiphoton intrapulse interference phase scan (MIIPS) for phase shaping and iterative amplitude optimization to achieve Gaussian-like tunable sub-20 fs pulses with output powers of up to 142 mW as well as nontunable pulses with 310 mW output power as short as 11.5 fs. © 2011 Optical Society of America

  1. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, V M; El' tsov, A V; Khristoforov, O B [State Research Center of Russian Federation ' Troitsk Institute for Innovation and Fusion Research' , Troitsk, Moscow Region (Russian Federation)


    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al{sub 2}O{sub 3} ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse{sup -1}, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ ≤ 0.7%) is achieved using an all-solid-state pump system. (lasers)

  2. All-fiber high-power monolithic femtosecond laser at 1.59 µm with 63-fs pulse width (United States)

    Hekmat, M. J.; Omoomi, M.; Gholami, A.; Yazdabadi, A. Bagheri; Abdollahi, M.; Hamidnejad, E.; Ebrahimi, A.; Normohamadi, H.


    In this research, by adopting an alternative novel approach to ultra-short giant pulse generation which basically originated from difficulties with traditional employed methods, an optimized Er/Yb co-doped double-clad fiber amplifier is applied to boost output average power of single-mode output pulses to a high level of 2-W at 1.59-µm central wavelength. Output pulses of approximately 63-fs pulse width at 52-MHz repetition rate are obtained in an all-fiber monolithic laser configuration. The idea of employing parabolic pulse amplification for stretching output pulses together with high-power pulse amplification using Er/Yb co-doped active fibers for compressing and boosting output average power plays crucial role in obtaining desired results. The proposed configuration enjoys massive advantages over previously reported literature which make it well-suited for high-power precision applications such as medical surgery. Detailed dynamics of pulse stretching and compressing in active fibers with different GVD parameters are numerically and experimentally investigated.

  3. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate (United States)

    Borisov, V. M.; El'tsov, A. V.; Khristoforov, O. B.


    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al2O3 ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse-1, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ <= 0.7%) is achieved using an all-solid-state pump system.

  4. Proton radiography of magnetic fields generated with an open-ended coil driven by high power laser pulses

    Directory of Open Access Journals (Sweden)

    Guoqian Liao


    Full Text Available Recently generation of strong magnetic (B fields has been demonstrated in capacitor coils heated by high power laser pulses [S. Fujioka et al., Sci. Rep. 3, 1170 (2013]. This paper will present a direct measurement of B field generated with an open-ended coil target driven by a nanosecond laser pulse using ultrafast proton radiography. The radiographs are analyzed with particle-tracing simulations. The B field at the coil center is inferred to be ∼50 T at an irradiance of ∼5 × 1014 W·cm−2. The B field generation is attributed to the background cold electron flow pointing to the laser focal spot, where a target potential is induced due to the escape of energetic electrons.

  5. Experimental investigation of high power pulsed 2.8 μm Er3+-doped ZBLAN fiber lasers (United States)

    Shen, Yanlong; Wang, Yishan; Huang, Ke; Luan, Kunpeng; Chen, Hongwei; Tao, Mengmeng; Yu, Li; Yi, Aiping; Si, Jinhai


    We report on the recent progress on high power pulsed 2.8 μm Er3+-doped ZBLAN fiber laser through techniques of passively and actively Q-switching in our research group. In passively Q-switched operation, a diode-cladding-pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) was demonstrated. Stable pulse train was produced at a slope efficient of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ. The maximum peak power was calculated to be 21.9 W. In actively Q-switched operation, a diode-pumped actively Q-switched Er3+-doped ZBLAN fiber laser at 2.8 μm with an optical chopper was reported. The maximum laser pulse energy of up to 130 μJ and a pulse width of 127.3 ns at a repetition rate of 10 kHz with an operating wavelength of 2.78 μm was obtained, yielding the maximum peak power of exceeding 1.1 kW.

  6. High-power terahertz optical pulse generation with a dual-wavelength harmonically mode-locked Yb:YAG laser (United States)

    Zhuang, W. Z.; Chang, M. T.; Su, K. W.; Huang, K. F.; Chen, Y. F.


    We report on high-power terahertz optical pulse generation with a dual-wavelength harmonically mode-locked Yb:YAG laser. A semiconductor saturable absorber mirror is developed to achieve synchronously mode-locked operation at two spectral bands centered at 1031.67 and 1049.42 nm with a pulse duration of 1.54 ps and a pulse repetition rate of 80.3 GHz. With a diamond heat spreader to improve the heat removal efficiency, the average output power can be up to 1.1 W at an absorbed pump power of 5.18 W. The autocorrelation traces reveal that the mode-locked pulse is modulated with a beat frequency of 4.92 THz and displays a modulation depth to be greater than 80%.

  7. Simulation and initial experiments of a high power pulsed TEA CO2 laser (United States)

    Torabi, R.; Saghafifar, H.; Koushki, A. M.; Ganjovi, A. A.


    In this paper, the output characteristics of a UV pin array pre-ionized TEA CO2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.

  8. High power lasers & systems


    Chatwin, Chris; Young, Rupert; Birch, Philip


    Some laser history;\\ud Airborne Laser Testbed & Chemical Oxygen Iodine Laser (COIL);\\ud Laser modes and beam propagation;\\ud Fibre lasers and applications;\\ud US Navy Laser system – NRL 33kW fibre laser;\\ud Lockheed Martin 30kW fibre laser;\\ud Conclusions

  9. Narrow Energy-Spread Proton Beams Generated in a Gas Jet by High-Power CO2 Laser Pulses (United States)

    Haberberger, D.; Tochitsky, S.; Gong, C.; Mori, W.; Joshi, C.; Fiuza, F.; Fonseca, R.; Silva, L.


    At the UCLA Neptune Laboratory, we have investigated laser driven ion acceleration using a high-power CO2 laser pulse in a H2 gas jet tuned around the critical plasma density of 10^19cm-3 for 10μm light. The CO2 laser pulses consist of a train of 3ps pulses separated by 18ps with a peak power of up to 4TW and total energy of 50J [1]. Protons have been accelerated from this interaction to energies up to 22MeV, which far exceeds that predicted by ponderomotive force scaling for our vacuum ao˜2. Furthermore, these high energy protons are contained within an energy spread of δE/EFWHM ˜ 1%, and have an estimated transverse emittance of down to ˜1mm.mrad. The evolution of the plasma density profile was probed with 532nm interferometry revealing a steep rise (< 10 λ) to overcritical densities followed by long exponential fall on the back side of the plasma. 2D OSIRIS simulations run with the experimentally measured plasma density profile have uncovered a multistage process for the production of monoenergetic protons based on the shock acceleration mechanism which will be discussed.[4pt][1] D. Haberberger et. al., Opt. Exp. 18, 17865 (2010)

  10. High-power single-frequency pulsed laser based on a Yb-doped large-pitch photonic crystal fiber (United States)

    Cha, Yong-Ho; Kim, Yonghee; Park, Hyunmin; Lim, Gwon; Ko, Kwang-Hoon; Kim, Taek Soo; Jeong, Do-Young


    We have developed a high-power single-frequency pulsed fiber laser system utilizing a Yb-doped rod-type large-pitch photonic crystal fiber. The maximal peak power is 33 kW with a 0.4-mJ pulse energy and a 70-MHz linewidth, and the average power is 60 W at a 150-kHz repetition rate. At a higher repetition rate, the average power can be increased to 190 W, which is limited by the onset of transverse-mode instability in the large-pitch photonic crystal fiber. The output beam is linearly polarized and shows a good beam quality with a M2 value of 1.2.

  11. High-power noise-like pulse generation using a 1.56-µm all-fiber laser system. (United States)

    Lin, Shih-Shian; Hwang, Sheng-Kwang; Liu, Jia-Ming


    We demonstrated an all-fiber, high-power noise-like pulse laser system at the 1.56-µm wavelength. A low-power noise-like pulse train generated by a ring oscillator was amplified using a two-stage amplifier, where the performance of the second-stage amplifier determined the final output power level. The optical intensity in the second-stage amplifier was managed well to avoid not only the excessive spectral broadening induced by nonlinearities but also any damage to the device. On the other hand, the power conversion efficiency of the amplifier was optimized through proper control of its pump wavelength. The pump wavelength determines the pump absorption and therefore the power conversion efficiency of the gain fiber. Through this approach, the average power of the noise-like pulse train was amplified considerably to an output of 13.1 W, resulting in a power conversion efficiency of 36.1% and a pulse energy of 0.85 µJ. To the best of our knowledge, these amplified pulses have the highest average power and pulse energy for noise-like pulses in the 1.56-µm wavelength region. As a result, the net gain in the cascaded amplifier reached 30 dB. With peak and pedestal widths of 168 fs and 61.3 ps, respectively, for the amplified pulses, the pedestal-to-peak intensity ratio of the autocorrelation trace remains at the value of 0.5 required for truly noise-like pulses.

  12. High power lasers

    CERN Document Server

    Niku-Lari, A


    The use of lasers for the working and treatment of materials is becoming increasingly common in industry. However, certain laser applications, for example, in welding, cutting and drilling, are more widely exploited than others. Whilst the potential of lasers for the surface treatment of metals is well recognised, in practice, this particular application is a relative newcomer. The 24 papers in this volume present the latest research and engineering developments in the use of lasers for processes such as surface melting, surface alloying and cladding, and machining, as well as discussing th

  13. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)


    power laser generation using Yb-doped double-clad fibres with conversion efficiencies in excess of 80% have attracted much attention during the last decade due to their inherent advantages in terms of very high efficiency, ...

  14. High power CO2 laser development with AOM integration for ultra high-speed pulses (United States)

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard; Jamalieh, Murad


    There is a 500 billion USD world market for packaging expected to grow to a trillion in 2030. Austria plays an important role world wide for high speed laser engraving applications — especially when it comes to high end solutions. Such high end solutions are fundamental for the production of print forms for the packaging and decorating industry (e. g. cans). They are additionally used for security applications (e. g. for printing banknotes), for the textile printing industry and for creating embossing forms (e. g. for the production of dashboards in the automotive industry). High speed, high precision laser engraving needs laser resonators with very stable laser beams (400 - 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure - stable within the sub-micrometer range - a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench using hexapods, allowing to optimize the complete beam path with collimators and AOM. The major steps related to laser engraving of dry offset printing plates during the full workflow from the artists design to the printed result on an aluminum can is presented in this paper as well as laser characteristics, AOM integration and correlative CLSM and SEM investigation of the results.

  15. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... This mirror along with the other cleaved end of the Yb-doped fibre provid- ing 4% Fresnel reflection act as resonator mirrors. Another dichroic mirror with HT at. 975 nm and HR in a broadband from 1040 to 1100 nm at 25. ◦ angle of incidence has been placed between the two lenses to take out the laser ...

  16. Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

    Directory of Open Access Journals (Sweden)

    S. S. Bulanov


    Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

  17. Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

    CERN Document Server

    Bulanov, S S; Schroeder, C B; Leemans, W P; Bulanov, S V; Margarone, D; Korn, G; Haberer, T


    The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He3 ions, having almost the same penetration depth as He4 with the ...

  18. High-power, mid-infrared, picosecond pulses generated by compression of a CO2 laser beat-wave in GaAs

    CERN Document Server

    Pigeon, J J; Joshi, C


    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  19. High power gas laser amplifier (United States)

    Leland, Wallace T.; Stratton, Thomas F.


    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  20. Generation of High-Power High-Intensity Short X-Ray Free-Electron-Laser Pulses. (United States)

    Guetg, Marc W; Lutman, Alberto A; Ding, Yuantao; Maxwell, Timothy J; Decker, Franz-Josef; Bergmann, Uwe; Huang, Zhirong


    X-ray free-electron lasers combine a high pulse power, short pulse length, narrow bandwidth, and high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key x-ray free-electron laser applications including single-molecule imaging and novel nonlinear x-ray methods. This Letter shows experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.

  1. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge (United States)

    Bulaev, V. D.; Lysenko, S. L.


    A high-power repetitively pulsed e-beam-controlled discharge CO2 laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers.

  2. Optics assembly for high power laser tools (United States)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.


    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  3. High power-pulsed Nd:YAG laser as a new stimulus to induce BMP-2 expression in MC3T3-E1 osteoblasts. (United States)

    Kim, In Sook; Cho, Tae Hyung; Kim, Kwansik; Weber, Franz E; Hwang, Soon Jung


    High-power laser has recently become a physical stimulus for bone regeneration. Little is known about how high-power laser irradiation affects osteoblast differentiation. This study investigated osteoblast responses to high-power laser and combined irradiation with BMP-2 treatment. MC3T3-E1 pre-osteoblasts were exposed to laser irradiation, 100 ng/ml BMP-2 or both. Cells were irradiated with a Q-switched, pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, with a 1,064 nm wavelength and 0.75 W output power under 1.5, 3, or 5 J/cm(2) energy densities. Cell proliferation was evaluated using tetrazolium salt, WST-8. To determine the effect of these treatments on in vitro osteogenesis, we examined alkaline phosphatase (ALP) activity, mineral deposition, and expression of genes associated with osteogenesis. Quantitative real time PCR or ELISA was used to examine cytokine expression. In each experiment, either non-irradiated or BMP-2 (100 ng/ml)-treated cells were used as controls. High-power, low-level, Nd:YAG laser irradiation significantly increased ALP activity, when combined with BMP-2 or not. Cell proliferation declined in the irradiation and combined irradiation/BMP-2 groups. Interestingly, Nd:YAG laser stimulation resulted in significant induction of endogenous BMP-2 protein and gene expression. The increased expression of upstream regulators cbfa1 by Nd:YAG laser alone was comparable to exogenous BMP-2 treatment (100 ng/ml). Combined laser/BMP-2 treatment was synergistic in the expression of some genes (IGF-1, cbfa1) and ALP activity, compared to both BMP-2 treatment and laser irradiation alone. In vitro matrix mineralization was significantly accelerated by laser stimulation compared to that of the control, more so than with the combined laser/BMP-2 treatment. The present in vitro findings demonstrate that high-power, low-level Nd:YAG laser increased osteoblast activity, very efficiently accelerating mineral deposition. Osteoinductive effect of laser

  4. High power terahertz radiation generation by optical rectification of a shaped pulse laser in axially magnetized plasma (United States)

    Singh, Ram Kishor; Singh, Monika; Rajouria, Satish Kumar; Sharma, R. P.


    An analytical expression has been derived for terahertz (THz) emission by optical rectification of a laser pulse having a Gaussian as well as hyperbolic-secant shape in axially magnetised ripple density plasma. The interaction between short laser pulses of sub picoseconds duration and plasma leads to the radiation of a wave having frequency in THz regime. The non-uniform intensity profile, say supper-Gaussian, of laser beam exerts a quasi-static ponderomotive force to the electron. The electron acquired a nonlinear transverse drift velocity component. Hence, a strong transient current density having a frequency component in the THz regime produces due to coupling of this velocity component with ripple density plasma and derives a strong THz wave. The generated THz field amplitude is directly proportional to the amplitude of the density ripple and field amplitude of the laser beam. In this generation mechanism, the ripple wave number plays a critical role. The THz field amplitude is maximized when cyclotron frequency approaches to the THz frequency and higher value of profile index. For typical laser plasma parameter, the emitted normalised amplitude of THz field is on the order of 10-2.

  5. High power regenerative laser amplifier (United States)

    Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.


    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  6. Methods for High Power EM Pulse Measurement

    Directory of Open Access Journals (Sweden)

    P. Fiala


    Full Text Available There are some suitable methods for the measurement of ultra-short solitary electromagnetic pulses that can be generated by high power pulsed generators. The measurement methods properties have to correspond to the fact whether we want to measure pulses of voltage, current or free-space electromagnetic wave. The need for specific measurement methods occurred by the development of high power microwave pulse generator. Applicable methods are presented in this paper. The method utilizing Faraday's induction law allows the measurement of generated current. For the same purpose the magneto-optic method can be utilized, with its advantages. For measurement of output microwave pulse of the generator the calorimetric method was designed and realized.

  7. Time-resolved electron thermal conduction by probing of plasma formation in transparent solids with high power subpicosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Brian -Tinh Van [Univ. of California, Davis, CA (United States)


    This dissertation work includes a series of experimental measurements in a search for better understanding of high temperature (104-106K) and high density plasmas (1022-1024cm-3) produced by irradiating a transparent solid target with high intensity (1013 - 1015W/cm2) and subpicosecond (10-12-10-13s) laser pulses. Experimentally, pump and probe schemes with both frontside (vacuum-plasma side) and backside (plasma-bulk material side) probes are used to excite and interrogate or probe the plasma evolution, thereby providing useful insights into the plasma formation mechanisms. A series of different experiments has been carried out so as to characterize plasma parameters and the importance of various nonlinear processes. Experimental evidence shows that electron thermal conduction is supersonic in a time scale of the first picosecond after laser irradiation, so fast that it was often left unresolved in the past. The experimental results from frontside probing demonstrate that upon irradiation with a strong (pump) laser pulse, a thin high temperature (~40eV) super-critical density (~1023/cm3) plasma layer is quickly formed at the target surface which in turn becomes strongly reflective and prevents further transmission of the remainder of the laser pulse. In the bulk region behind the surface, it is also found that a large sub-critical (~1018/cm3) plasma is produced by inverse Bremsstrahlung absorption and collisional ionization. The bulk underdense plasma is evidenced by large absorption of the backside probe light. A simple and analytical model, modified from the avalanche model, for plasma evolution in transparent materials is proposed to explain the experimental results. Elimination of the bulk plasma is then experimentally illustrated by using targets overcoated with highly absorptive films.

  8. High SBS-Threshold Er/Yb Co-Doped Phosphate Glass Fiber Amplifiers for High Power, Sub-us Pulsed, Narrow Linewidth, All Fiber-Based Laser Transmitter Project (United States)

    National Aeronautics and Space Administration — In order to implement the monolithic high power narrow linewidth pulsed all fiber-based laser transmitter by using a MOPA configuration for NASA's active remote...

  9. Investigation of CIS/CIGS and CdTe solar cells scribing with high-power fibre short pulse lasers (United States)

    Hernandez, Yves; Lotter, Erwin; Bermudez, Veronica; Bosio, Alessio; Salin, François; Hueske, Marc; Selleri, Stefano; Bertrand, Anthony; Duterte, Charles


    We present here some of the last results of the EUROPEAN project ALPINE. We present both the development of an adjustable fibre laser pulse source and scribing results on CdTe and CIGS solar cells. The scribing tests were performed at three different pulse durations: 400 fs, 8 ps and 250 ps. The results obtained with 250 ps are already very promising for P3 steps in both CdTe and CIGS solar cells. In both cases the results were validated electrically. In the case of P3 scribing for CIGS solar cells, shunt resistances as high as 125 kΩ.cm were obtained. Isolation resistances were higher than 1 MΩ.cm. The processing speed was 2 m/s.

  10. High power laser perforating tools and systems (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F


    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  11. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Calculation of mass transfer in the remote cutting of metals by radiation of a high-power repetitively pulsed CO2 laser (United States)

    Gladush, G. G.; Rodionov, N. B.


    The mechanism of remote cutting of steel plates by radiation of a high-power repetitively pulsed CO2 laser is theoretically studied. The models of melt removal by the gravity force and the recoil pressure of material vapour are proposed and the sufficient conditions for the initiation of cutting are determined. A numerical model of a thermally thin plate was employed to describe the cutting for large focal spots.

  12. Rapid heating of matter using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

  13. Hollow-core fibers for high power pulse delivery

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian


    We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

  14. High power diode lasers for solid-state laser pumps (United States)

    Linden, Kurt J.; Mcdonnell, Patrick N.


    The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

  15. High power lasers in manufacturing


    Chatwin, Chris R


    Lecture covers a brief history of lasers and the important beam parameters for manufacturing applications. It introduces the main laser types that are appropriate for manufacturing: carbon dioxide lasers, Nd YAG, Diode and fibre lasers, excimer lasers. It then looks at applications to different products and also micro-engineering

  16. Packaging of high power semiconductor lasers

    CERN Document Server

    Liu, Xingsheng; Xiong, Lingling; Liu, Hui


    This book introduces high power semiconductor laser packaging design. The characteristics and challenges of the design and various packaging, processing, and testing techniques are detailed by the authors. New technologies, in particular thermal technologies, current applications, and trends in high power semiconductor laser packaging are described at length and assessed.

  17. Development of a high power femtosecond laser

    CSIR Research Space (South Africa)

    Neethling, PH


    Full Text Available The Laser Research Institute and the CSIR National Laser Centre are developing a high power femtosecond laser system in a joint project with a phased approach. The laser system consists of an fs oscillator and a regenerative amplifier. An OPCPA...

  18. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian


    We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers......We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers...

  19. High-power CO lasers for materials processing (United States)

    Averin, A.; Erofeev, E.; Ionin, Andrei A.; Malysh, M.


    Two high-power CO laser installations for industrial applications are being developed now in Russia within the framework of the Eureka Project EU113 (`CO-Eurolaser'). The electron- beam-controlled-discharge (EBCD) method for pumping those lasers is used. The first one, EBCD 10 kW CO laser, operates in continuous wave and `gentle' repetitively pulsed (RP) (peak power 20 kW, laser pulse duration 0.5 - 1 ms, pulse repetition rate 500 - 1,000 Hz) modes. The second laser, EBCD 5 - 10 kW CO laser will operate in `tough' RP mode (peak power 0.2 - 1.0 MW, single pulse energy 100 J, pulse duration 0.1 - 0.5 ms, repetition rate 50 - 100 Hz). A detander-compressor device, the main characteristics of which are reported, will be used for cooling the laser mixture of the second CO laser. Those high-power CO laser installations are supposed to be used for investigation of different laser materials processing methods on 5 micrometers wavelength for deep penetration welding, cutting, and surface treatment and also for comparative materials processing studies on CO and CO2 laser wavelengths.

  20. Transient Plasma Photonic Crystals for High-Power Lasers. (United States)

    Lehmann, G; Spatschek, K H


    A new type of transient photonic crystals for high-power lasers is presented. The crystal is produced by counterpropagating laser beams in plasma. Trapped electrons and electrically forced ions generate a strong density grating. The lifetime of the transient photonic crystal is determined by the ballistic motion of ions. The robustness of the photonic crystal allows one to manipulate high-intensity laser pulses. The scheme of the crystal is analyzed here by 1D Vlasov simulations. Reflection or transmission of high-power laser pulses are predicted by particle-in-cell simulations. It is shown that a transient plasma photonic crystal may act as a tunable mirror for intense laser pulses. Generalizations to 2D and 3D configurations are possible.

  1. High Power Fiber Laser Test Bed (United States)

    Federal Laboratory Consortium — This facility, unique within DoD, power-combines numerous cutting-edge fiber-coupled laser diode modules (FCLDM) to integrate pumping of high power rare earth-doped...

  2. Overview on the high power excimer laser technology (United States)

    Liu, Jingru


    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  3. High power Ar-Xe laser

    NARCIS (Netherlands)

    Witteman, W.J.; Gielkens, S.W.A.; Tskhai, V.N.; Peters, P.J.M.


    The discharge conditions of the multi-atmospheric e-beam sustained Ar-Xe laser are investigated. It is observed that the quasi-stationary period of a laser pulse depends on the e-beam current, the discharge power deposition and the gas density. The laser efficiency can be as high as 8%. The pulse

  4. Ceramics for High Power Lasers (United States)


    UCF. At this writing, we are still awaiting its installation and commissioning at UCF. This shuffling of people and equipment caused a temporary...that of the old method of ultra -microscopy. Moriya and Ogawa who introduced focused laser radiation and applied this method to characterize a variety

  5. High-power optics lasers and applications

    CERN Document Server

    Apollonov, Victor V


    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 ...

  6. Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

    DEFF Research Database (Denmark)

    Bache, Morten; Wise, Frank W.


    using second-harmonic generation in a type-I phase-matching configuration. We find that because of competing cubic material nonlinearities, compression can only occur in the nonstationary regime, where group-velocity-mismatch–induced Raman-like nonlocal effects prevent compression to less than 100 fs......, and in particular the latter could become an issue when compressing such long crystals (around 10 cm long). We finally show that the second harmonic contains a short pulse locked to the pump and a long multi-picosecond red-shifted detrimental component. The latter is caused by the nonlocal effects...... in the nonstationary regime, but because it is strongly red-shifted to a position that can be predicted, we show that it can be removed using a bandpass filter, leaving a visible component of less than 100 fs at λ=515 nm with excellent pulse quality....

  7. Earthquake Triggering by High Power Electric Pulses (United States)

    Novikov, Victor; Konev, Yuri; Zeigarnik, Vladimir


    The study carried out by the Joint Institute for High Temperatures in cooperation with the Institute of Physics of the Earth and the Research Station in Bishkek of Russian Academy of Sciences in 1999-2008 showed a response of weak seismicity at field experiments with electric pulsed power systems, as well as acoustic emission of rock specimens under laboratory conditions on high-power electric current pulses applied to the rocks. It was suggested that the phenomenon discovered may be used in practice for partial release of tectonic stresses in the Earth crust for earthquake hazard mitigation. Nevertheless, the mechanism of the influence of man-made electromagnetic field on the regional seismicity is not clear yet. One of possible cause of the phenomenon may be pore fluid pressure increase in the rocks under stressed conditions due to Joule heat generation by electric current injected into the Earth crust. It is known that increase of pore fluid pressure in the fault zone over a critical pressure of about 0.05 MPa is sufficient to trigger an earthquake if the fault is near the critical state due to accumulated tectonic deformations. Detailed 3D-calculaton of electric current density in the Earth crust of the Northern Tien Shan provided by pulsed electric high-power system connected to grounded electric dipole showed that at the depth of earthquake epicenters (over 5 km) the electric current density is lower than 10-7 A/m2 that is not sufficient for increase of pressure in the fluid-saturated porous geological medium due to Joule heat generation, which may provide formation of cracks resulting in the fault propagation and release of tectonic stresses in the Earth crust. Nevertheless, under certain conditions, when electric current will be injected into the fault through the casing pipes of two deep wells with preliminary injection of conductive fluid into the fault, the current density may be high enough for significant increase of mechanic pressure in the porous two

  8. The Development of a High-Power, Pulsed Mid-Infrared Laser for a Two-Photon LIF Detection of Tropospheric OH (United States)

    Hannun, R. A.; Smith, J. B.; Witinski, M. F.; Anderson, J. G.


    The hydroxyl radical is universally recognized as the dominant oxidizing species in the earth's atmosphere. OH initiates the chemical transformation and degradation of greenhouse gases, pollutants, and volatile organic compounds and plays a critical role in both urban ozone pollution and aerosol formation. Because of its high reactivity, OH radicals have an atmospheric lifetime of less than a second and only reach mixing ratios of parts per trillion (ppt) in the free troposphere. The combination of these two factors makes in-situ observations of OH challenging. Laser-Induced Fluorescence (LIF) is a highly sensitive technique that has been successfully applied to measurements of stratospheric OH. The LIF technique has also been adapted to instrumentation for OH observations in the troposphere. However, results for tropospheric OH have been inconclusive due to poorly understood interferences, and large discrepancies exist between modeled and measured OH concentrations. A Two-Photon LIF (TP-LIF) technique has been proposed as a means of enhancing sensitivity by shifting to lower-energy pumping frequencies, which also minimizes laser-induced interference pathways. In this detection scheme, OH is pumped into an excited vibrational state and subsequently pumped into an excited electronic state. A major limitation in the sensitivity of the TP-LIF detection scheme has been the lack of a mid-infrared (mid-IR) light source with enough power to adequately pump the vibrational transition. We have developed a high-power, pulsed laser system at 2.97 μm using an optical parametric generator (OPG). The OPG system delivers narrow-linewidth, tunable radiation with high peak-power to substantially populate the vibrational excitation. The development of the OPG laser system effectively addresses the major challenge in the TP-LIF detection of OH.

  9. High Power Diode Lasers Technology and Applications

    CERN Document Server

    Bachmann, Friedrich; Poprawe, Reinhart


    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...

  10. Germanate Glass Fiber Lasers for High Power (United States)


    AFRL-AFOSR-JP-TR-2016-0020 Germanate glass fiber lasers for high power David Lancaster THE UNIVERSITY OF ADELAIDE Final Report 01/04/2016...COVERED (From - To) 01-07-2014 to 30-06-2015 4. TITLE AND SUBTITLE Germanate glass fiber lasers for high power 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER...germanate based glasses with a specific focus on glass stability during thermal-cycling which is representative of the steps required to fabricate a doped

  11. Compact High Power Fiber Laser Project (United States)

    National Aeronautics and Space Administration — The goal of the proposed work is the development of a portable and efficient pulsed laser system for LIDAR and ranging applications, which make use of the latest...

  12. Elimination of self-mode-locking pulses in high-power continuous-wave Yb-doped fiber lasers with external feedback. (United States)

    Xu, Haiyang; Jiang, Man; Zhou, Pu; Zhao, Guomin; Gu, Xijia


    Sustained self-pulsing and self-mode-locking (SML) are detrimental to the performance of continuous-wave (CW) fiber lasers. We demonstrate an all-fiber method to eliminate SML pulsing by employing a low-reflectivity fiber Bragg grating (FBG) outside of a laser cavity to provide feedback. A narrow-bandwidth FBG is used to form an external cavity with the output coupler FBG, which suppresses the SML up to a certain output power level, at which point, the laser emission linewidth is still within the bandwidth of the FBG. On the other hand, a broad-bandwidth FBG forms a chirped cavity with the output coupler FBG, which can suppress the SML at a much higher power level, tested up to 50 W. This method provides a simple effective all-fiber solution for suppressing self-pulsing in CW fiber lasers at high pump levels with no need to change the laser configuration.

  13. High power solid state laser modulator (United States)

    Birx, Daniel L.; Ball, Don G.; Cook, Edward G.


    A multi-stage magnetic modulator provides a pulse train of .+-.40 kV electrical pulses at a 5-7 kHz repetition rate to a metal vapor laser. A fractional turn transformer steps up the voltage by a factor of 80 to 1 and magnetic pulse compression is used to reduce the pulse width of the pulse train. The transformer is fabricated utilizing a rod and plate stack type of construction to achieve a high packing factor. The pulses are controlled by an SCR stack where a plurality of SCRs are electrically connected in parallel, each SCR electrically connected to a saturable inductor, all saturable inductors being wound on the same core of magnetic material for enhanced power handling characteristics.

  14. Multiple-pass amplifiers for high-power laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Jackel, S.; Givon, M.; Ludmirsky, A.; Eliezer, S.; Borowitz, J.L.; Arad, B.; Zigler, A.; Gazit, Y.


    Multiple-pass amplifiers were configured from Nd:glass rods using polarization and angular coupling techniques. Very high gain (>600) single beam triple-pass booster stages and high gain (30 or 15) single or double-beam double-pass amplifiers were combined to construct a very cost effective high-power (50 GW) pulsed laser system. These techniques were also effectively applied to smaller compact high repetition-rate systems.

  15. Transmission grating stretcher for contrast enhancement of high power lasers. (United States)

    Tang, Yunxin; Hooker, Chris; Chekhlov, Oleg; Hawkes, Steve; Collier, John; Rajeev, P P


    We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal.

  16. 175 fs-long pulses from a high-power single-mode Er-doped fiber laser at 1550 nm (United States)

    Elahi, Parviz; Kalaycıoğlu, Hamit; Li, Huihui; Akçaalan, Önder; Ilday, F. Ömer


    Development of Er-doped ultrafast lasers have lagged behind the corresponding developments in Yb- and Tm-doped lasers, in particular, fiber lasers. Various applications benefit from operation at a central wavelength of 1.5 μm and its second harmonic, including emerging applications such as 3D processing of silicon and 3D printing based on two-photon polymerization. We report a simple, robust fiber master oscillator power amplifier operating at 1.55 μm, implementing chirp pulse amplification using single-mode fibers for diffraction-limited beam quality. The laser generates 80 nJ pulses at a repetition rate of 43 MHz, corresponding to an average power of 3.5 W, which can be compressed down to 175 fs. The generation of short pulses was achieved using a design which is guided by numerical simulations of pulse propagation and amplification and manages to overturn gain narrowing with self-phase modulation, without invoking excessive Raman scattering processes. The seed source for the two-stage amplifier is a dispersion-managed passively mode-locked oscillator, which generates a ∼40 nm-wide spectrum and 1.7-ps linearly chirped pulses.

  17. Strong doping of the n-optical confinement layer for increasing output power of high- power pulsed laser diodes in the eye safe wavelength range (United States)

    Ryvkin, Boris S.; Avrutin, Eugene A.; Kostamovaara, Juha T.


    An analytical model for internal optical losses at high power in a 1.5 μm laser diode with strong n-doping in the n-side of the optical confinement layer is created. The model includes intervalence band absorption by holes supplied by both current flow and two-photon absorption (TPA), as well as the direct TPA effect. The resulting losses are compared with those in an identical structure with a weakly doped waveguide, and shown to be substantially lower, resulting in a significant improvement in the output power and efficiency in the structure with a strongly doped waveguide.

  18. High-power repetitively pulsed CO{sub 2} laser with mechanical Q-switching and its application to studies in aerodynamic installations

    Energy Technology Data Exchange (ETDEWEB)

    Malov, Aleksei N; Orishich, Anatolii M; Shulyat' ev, Viktor B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)


    A new method for organising the repetitively pulsed regime of CO{sub 2} laser oscillation at the expense of a self-filtering resonator and two concave cylindrical mirrors with equal curvature in the intracavity modulator is considered. The studies of the energy and temporal characteristics of the laser radiation show that the constructed laser has high efficiency close to that of a cw laser. The mean and pulse power of 4.5 and 200 kW, respectively, are obtained. For a wide range of gas-dynamic characteristics the possibility of the optical breakdown in the supersonic wide-aperture air flow is demonstrated. The coefficient of absorption of laser radiation in optical breakdown plasma in a supersonic air flow is investigated and its value amounting to 60% is obtained. For the first time it is found that the threshold density of air, corresponding to the efficiency jump, is equal to 1.8 - 2 kg m{sup -3} and independent of the Mach number M = 1.7 - 3.7. (lasers)

  19. Cryogenic cooling for high power laser amplifiers

    Directory of Open Access Journals (Sweden)

    Perin J.P.


    Full Text Available Using DPSSL (Diode Pumped Solid State Lasers as pumping technology, PW-class lasers with enhanced repetition rates are developed. Each of the Yb YAG amplifiers will be diode-pumped at a wavelength of 940 nm. This is a prerequisite for achieving high repetition rates (light amplification duration 1 millisecond and repetition rate 10 Hz. The efficiency of DPSSL is inversely proportional to the temperature, for this reason the slab amplifier have to be cooled at a temperature in the range of 100 K–170 K with a heat flux of 1 MW*m−2. This paper describes the thermo-mechanical analysis for the design of the amplification laser head, presents a preliminary proposal for the required cryogenic cooling system and finally outlines the gain of cryogenic operation for the efficiency of high pulsed laser.

  20. High power diode lasers converted to the visible

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Andersen, Peter E.


    High power diode lasers have in recent years become available in many wavelength regions. However, some spectral regions are not well covered. In particular, the visible spectral range is lacking high power diode lasers with good spatial quality. In this paper, we highlight some of our recent...... results in nonlinear frequency conversion of high power near infrared diode lasers to the visible spectral region....

  1. High power UV and VUV pulsed excilamps (United States)

    Tarasenko, V.; Erofeev, M.; Lomaev, M.; Rybka, D.


    Emission characteristics of a nanosecond discharge in inert gases and its halogenides without preionization of the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam (VDIAEB) was realized at pressures up to 12 atm. In xenon at pressure of 1.2 atm, the energy of spontaneous radiation in the full solid angle was sim 45 mJ/cm^3, and the FWHM of a radiation pulse was sim 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed radiant exitance of inert gases halogenides excited by VDIAEB was sim 4.5 kW/cm^2 at efficiency up to 5.5 %.

  2. Innovations in high power fiber laser applications (United States)

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


    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.

  3. Laser-driven plasma photonic crystals for high-power lasers (United States)

    Lehmann, G.; Spatschek, K. H.


    Laser-driven plasma density gratings in underdense plasma are shown to act as photonic crystals for high power lasers. The gratings are created by counterpropagating laser beams that trap electrons, followed by ballistic ion motion. This leads to strong periodic plasma density modulations with a lifetime on the order of picoseconds. The grating structure is interpreted as a plasma photonic crystal time-dependent property, e.g., the photonic band gap width. In Maxwell-Vlasov and particle-in-cell simulations it is demonstrated that the photonic crystals may act as a frequency filter and mirror for ultra-short high-power laser pulses.

  4. Apparatus for advancing a wellbore using high power laser energy (United States)

    Zediker, Mark S.; Land, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Koblick, Yeshaya; Moxley, Joel F.


    Delivering high power laser energy to form a borehole deep into the earth using laser energy. Down hole laser tools, laser systems and laser delivery techniques for advancement, workover and completion activities. A laser bottom hole assembly (LBHA) for the delivery of high power laser energy to the surfaces of a borehole, which assembly may have laser optics, a fluid path for debris removal and a mechanical means to remove earth.

  5. Measurement of high-power microwave pulse under intense ...

    Indian Academy of Sciences (India)

    KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator (VIRCATOR) device. HPM power measurements were carried out using a transmitting–receiving system in the presence of intense high frequency (a few MHz) ...

  6. Parametric design and protective strategy of energy module for SG-III high power laser

    CERN Document Server

    Liu Ke Fu; Qing Shi Hong; Pan Yuan; Yao Zeng Gan; Pi Zhang; Zheng Wan Guo; Guo Liang Fu; Zhou Pei Zhang; Li Yi Zheng; Chen De Huai


    The author presented the circuitry design and principle of parameters choice of the energy module for SG-III high power laser. All possible faults of high pulsed power supply were analyzed in detail. Based on the analysis and computation, the protective strategy and technology was put forward. It is helpful for the design and safe operation of high power supply and laser amplifier system. The experiments showed that the manufactured pulsed power supply met the system requirements

  7. A High Power Frequency Doubled Fiber Laser (United States)

    Thompson, Rob; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute


    This slide presentation reviews the power frequencies for the doubled fiber laser. It includes information on the 780 nm laser, second harmonic generation in one crystal, cascading crystals, the tenability of laser systems, laser cooling, and directions for future work.

  8. Development of High Power Lasers for Materials Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Hackel, L A


    The Lawrence Livermore National Laboratory (LLNL) has a long history of developing high power lasers for use in basic science and applications. The Laser Science and Technology Program (LS&T) at LLNL supports advanced lasers and optics development both for the National Ignition Facility (NIF) as well as for high power lasers and optics technology for a broader range of government, military and industrial applications. The NIF laser is currently under construction with the first of the 192 beamlines being activated. When finished NIF will have an output energy of 2 MJ at 351 nm. This system will be used for studies of high energy density physics, equation of state and inertial confinement fusion. It is now generally acknowledged that the future of laser missile defense lies with solid state lasers. The leading laser technology for theater missile defense is under development within the LS&T and funded by the US Army SMDC. This high average power technology is based on a solid state laser operated in a heat capacity mode. In the concept the heat producing lasing cycle is separated in time from the cooling cycle thus reducing thermal gradients and allowing significantly greater average output power. Under the current program, an LLNL developed laser has achieved a record setting 13 kW of average power in 20 second duration bursts. We have also performed target lethality experiments showing a previously unrecognized advantage of a pulsed laser format. The LLNL work is now focused on achieving improved output beam quality and in developing a 100 kW output with diode pumping of a large aperture crystal gain medium on a compact mobile platform. The Short Pulse Laser Group of LS&T has been developing high power short pulse laser systems for a number of applications. Of great importance is petawatt (10{sup 12} Watt) and greater power output to support experiments on the NIF. We are developing a system of 5 M class output and 5 to 10 ps pulse duration for generating intense

  9. High power laser workover and completion tools and systems (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F


    Workover and completion systems, devices and methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena. Systems and devices for the laser workover and completion of a borehole in the earth. These systems and devices can deliver high power laser energy down a deep borehole, while maintaining the high power to perform laser workover and completion operations in such boreholes deep within the earth.

  10. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.


    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  11. Improved cutting performance in high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove


    Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described.......Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described....

  12. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization


    Gianluigi Caccianiga; Marco Baldoni; Carlo Angelo Ghisalberti; Alessio Paiusco


    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980?nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblast...

  13. High-power IR laser in SMT package (United States)

    Pritsch, Benedikt; Behringer, Martin; Arzberger, Markus; Wiesner, Christoph; Fehse, Robin; Heerlein, Jörg; Maric, Josip; Giziewicz, Wojciech


    Laser dies in an optical power range of 1-3 Watts are widely assembled in popular TO- packages. TO-packages suffer from high thermal resistance and limited output power. Bad thermal contact between circuit boards and TO-devices can cause overheating of laser chips, significantly reducing the operating life time. We developed a compact high heat-load SMT package for an optical power up to 7 Watts in CW operation with good life time results. The new package for high power laser chips combines highly efficient heat dissipation with Surface-mount technology. A Direct-Bonded-Copper (DBC) substrate acts as a base plate for the laser chip and heat sink. The attached frame is used for electrical contacting and acts as beam reflector where the laser light is reflected at a 45° mirror. In the application the DBC base plate of the SMT-Laser is directly soldered to a Metal-Core-PCB by reflow soldering. The overall thermal resistance from laser chip to the bottom of a MC-PCB was measured as low as 2.5 K/W. The device placement process can be operated by modern high-speed mounting equipment. The direct link between device and MC-PCB allows CW laser operation up to 6-7 watts at wavelengths of 808nm to 940nm without facing any overheating symptom like thermal roll over. The device is suitable for CW and QCW operation. In pulsed operation short rise and fall times of <2ns have been demonstrated. New application fields like infrared illumination for sensing purposes in the automotive industry and 3D imaging systems could be opened by this new technology.

  14. Waveform agile high-power fiber laser illuminators for directed-energy weapon systems (United States)

    Engin, Doruk; Lu, Wei; Kimpel, Frank; Gupta, Shantanu


    A kW-class fiber-amplifier based laser illuminator system at 1030nm is demonstrated. At 125 kHz pulse repetition rate, 1.9mJ energy per pulse (235W average power) is achieved for 100nsec pulses with >72% optical conversion efficiency, and at 250kHz repetition, >350W average power is demonstrated, limited by the available pumps. Excellent agreement is established between the experimental results and dynamic fiber amplifier simulation, for predicting the pulse shape, spectrum and ASE accumulation throughout the fiber-amplifier chain. High pulse-energy, high power fiber-amplifier operation requires careful engineering - minimize ASE content throughout the pre-amplifier stages, use of large mode area gain fiber in the final power stage for effective pulse energy extraction, and pulse pre-shaping to compensate for the laser gain-saturation induced intra-pulse and pulse-pattern dependent distortion. Such optimization using commercially available (VLMA) fibers with core size in the 30-40μm range is estimated to lead to >4mJ pulse energy for 100nsec pulse at 50kHz repetition rate. Such waveform agile high-power, high-energy pulsed fiber laser illuminators at λ=1030nm satisfies requirements for active-tracking/ranging in high-energy laser (HEL) weapon systems, and in uplink laser beacon for deep space communication.

  15. Multiple pulse electron beam converter design for high power radiography (United States)

    Pincosy, P. A.; Back, N.; Bergstrom, P. M.; Chen, Yu-Jiuan; Poulsen, P.


    The typical response of the x-ray converter material to the passage of a high-powered relativistic electron beam is vaporization and rapid dispersal. The effect of this dispersal on subsequent pulses for multi-pulse radiography is the collective effects on the propagation of the electron beam through the expanding plasma and the reduced number of electron to photon interactions. Thus, for the dual-axis radiographic hydrodynamic test facility, the converter material must either be replaced or confined long enough to accommodate the entire pulse train. Typically the 1-mm-thick high Z and full density converter material is chosen to give peak dose and minimum radiographic spot. For repeated pulses we propose a modified converter, constructed of either low density, high Z material in the form of foam or of foils spaced over ten times the axial thickness of the standard 1 mm converter. The converter material is confined within a tube to impede outward motion in radius outside the beam interaction region. We report single-pulse experiments which measure the dose and spot size produced by the modified converter and compare them to similar measurements made by the standard converter. For multiple pulses over a microsecond time scale, we calculate the radial and axial hydrodynamic flow to study the material reflux into the converter volume and the resultant density decrease as the electron beam energy is deposited. Both the electron transport through the expanding low density plasma and beam in the higher density material are modeled. The x-ray source dose and spot size are calculated to evaluate the impact of the changing converter material density distribution on the radiographic spot size and dose. The results indicate that a multiple-pulse converter design for three or four high-power beam pulses is feasible.

  16. High power laser downhole cutting tools and systems (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F


    Downhole cutting systems, devices and methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena. Systems and devices for the laser cutting operations within a borehole in the earth. These systems and devices can deliver high power laser energy down a deep borehole, while maintaining the high power to perform cutting operations in such boreholes deep within the earth.

  17. High Power Fiber Lasers and Applications to Manufacturing (United States)

    Richardson, Martin; McComb, Timothy; Sudesh, Vikas


    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.

  18. Absorption spectra measurements of the x-ray radiation heated sio{sub 2} aerogel plasma in 'dog-bone' targets irradiated by high power laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y; Dong, Q-L; Wang, S-J; Li, Y-T; Zhang, J [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Wei, H-G; Shi, J-R; Zhao, G [National Astronomical Observatories of China, Chinese Academy of Sciences. Beijing 100012 (China); Zhang, J-Y; Wen, T-S; Zhang, W-H; Hu, X; Liu, S-Y; Ding, Y-K; Zhang, L; Tang, Y-J; Zhang, B-H; Zheng, Z-J [Research Center for Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Nishimura, H; Fujioka, S [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)], E-mail:, E-mail:, E-mail: (and others)


    We studied the opacity effect of the SiO{sub 2} aerogel plasma heated by x-ray radiation produced by high power laser pulses irradiating the inner surface of golden 'dog-bone' targets. The PET crystal spectrometer was used to measure the absorption spectra of the plasmas in the range from 6.4 A to 7.4 A, among which the line emissions involving the K shell of Si ions from He-like to neutral atom were located. The experimental results were analyzed with Detailed-Level-Accounting method. As the plasma temperature increased, the characteristic lines of highly ionized ions gradually dominated the absorption spectrum.

  19. The interaction of high-power lasers with plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Eliezer, S


    , the author has not touched on the plasma based high energy charged particle accelerators, which involve short intense laser pulses and which are at the frontier of modern plasma physics. There is a nice chapter dealing with laser induced magnetic fields and waves in magnetized plasmas. The physics and mathematical details of the electron energy transport and heat waves, which are of significant interest in inertial confinement fusion, are described in depth. Comprehensive studies of shock waves and rarefaction waves are presented, and their relevance to high power pulsed laser drivers is discussed. Finally, the author has given a lucid description of hydrodynamic instabilities (i.e. the Rayleigh-Taylor, the Richtmyer-Meshkov, the Kelvin-Helmholtz), which are of great importance in laser-plasma interactions and in astrophysics. It would have been nice if the author would have also included a more physical description of the nonlinear evolution of those instabilities which play a significant role in the formation of fingers, bubbles and vortices in laboratories and in astrophysical settings. The book is well written and will serve as a valuable asset for graduate students and physicists working in the area of laser plasma interactions and high energy astrophysics. It should also be useful for teaching masters level courses on laser plasma interactions. The reviewer highly recommends the book to the interested reader. P K Shukla (book review)

  20. Thermal Response to High-Power Holmium Laser Lithotripsy. (United States)

    Aldoukhi, Ali H; Ghani, Khurshid R; Hall, Timothy L; Roberts, William W


    The aim of this study was to investigate "caliceal" fluid temperature changes during holmium laser activation/lithotripsy using settings up to 40 W power output with different irrigation flow rates. The experimental system consisted of a glass test tube (diameter 10 mm/length 75 mm) filled with deionized water, to mimic a calix. Real-time temperature was recorded using a thermocouple (Physitemp, NJ) positioned 5 mm from the bottom of the tube. A 200 μm laser fiber (Flexiva; Boston Scientific, MA) was introduced through the working channel of a disposable ureteroscope (LithoVue; Boston Scientific) and the laser fiber tip was positioned 15 mm above the bottom of the test tube. Deionized water irrigation (room temperature) through the working channel of the ureteroscope was delivered at flow rates of 0, 7-8, 14-15, and 38-40 mL/minute. A 120-W holmium laser (pulse 120; Lumenis, CA) was used. The following settings were explored: 0.5 J × 10 Hz, 1.0 J × 10 Hz, 0.5 J × 20 Hz, 1.0 J × 20 Hz, 0.5 J × 40 Hz, 1.0 J × 40 Hz, and 0.5 J × 80 Hz. During each experiment, the laser was activated continuously for 60 seconds. Temperature increased with increasing laser power output and decreasing irrigation flow rate. The highest temperature, 70.3°C (standard deviation 2.7), occurred with laser setting of 1.0 J × 40 Hz and no irrigation after 60 seconds of continuous laser firing. None of the tested laser settings and irrigation parameters produced temperature exceeding 51°C when activated for only 10 seconds of continuous laser firing. High-power holmium settings fired in long bursts with low irrigation flow rates can generate high fluid temperatures in a laboratory "caliceal" model. Awareness of this risk allows urologist to implement a variety of techniques (higher irrigation flow rates, intermittent laser activation, and potentially cooled irrigation fluid) to control and mitigate thermal

  1. High-power thulium fiber laser Q switched with single-layer graphene. (United States)

    Tang, Yulong; Yu, Xuechao; Li, Xiaohui; Yan, Zhiyu; Wang, Qi Jie


    We report high-power 2 μm Tm3+ fiber lasers passively Q switched by double-piece single-layer graphene transferred onto a glass plate. Through manipulating intracavity laser beam size and increasing pump ratios, an average power of 5.2 W is directly achieved from the laser oscillator with an optical-to-optical slope efficiency of 26%. The laser pulse energy can be as high as ∼18  μJ, comparable to that from actively Q-switched fiber lasers. The narrowest pulse width is 320 ns, and the pulse repetition rate can be tuned from tens of kilohertz to 280 kHz by changing the pump power. To the best of our knowledge, this is the highest average power and pulse energy, as well as the narrowest pulse width, from graphene-based Q-switched 2 μm fiber lasers.

  2. High Power Mid Wave Infrared Semiconductor Lasers

    National Research Council Canada - National Science Library

    Krishna, Sanjay; Dawson, Ralph


    .... We have also demonstrated room temperature photoluminescence up to 3 gm from InGaSb quantum wells grown on GaAs substrate. Using this approach we have fabricated optically pumped vertical cavity surface emitting lasers.

  3. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter


    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio....... Experimentally, we generate transverse current profiles by using standard lithography to define a digitated contact pad. Experimental results confirm that the current density is significantly altered and show completely filamentation-free operation up to 34 times threshold....

  4. High-power lasers for directed-energy applications. (United States)

    Sprangle, Phillip; Hafizi, Bahman; Ting, Antonio; Fischer, Richard


    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.

  5. High-power 95 GHz pulsed electron spin resonance spectrometer (United States)

    Hofbauer, W.; Earle, K. A.; Dunnam, C. R.; Moscicki, J. K.; Freed, J. H.


    High-field/high-frequency electron spin resonance (ESR) offers improved sensitivity and resolution compared to ESR at conventional fields and frequencies. However, most high-field/high-frequency ESR spectrometers suffer from limited mm-wave power, thereby requiring long mm-wave pulses. This precludes their use when relaxation times are short, e.g., in fluid samples. Low mm-wave power is also a major factor limiting the achievable spectral coverage and thereby the multiplex advantage of Fourier transform ESR (FTESR) experiments. High-power pulses are needed to perform two-dimensional (2D) FTESR experiments, which can unravel the dynamics of a spin system in great detail, making it an excellent tool for studying spin and molecular dynamics. We report on the design and implementation of a high-power, high-bandwidth, pulsed ESR spectrometer operating at 95 GHz. One of the principal design goals was the ability to investigate dynamic processes in aqueous samples at physiological temperatures with the intent to study biological systems. In initial experiments on aqueous samples at room temperature, we achieved 200 MHz spectral coverage at a sensitivity of 1.1×1010√s spins and a dead time of less than 50 ns. 2D-electron-electron double resonance experiments on aqueous samples are discussed to demonstrate the practical application of such a spectrometer.

  6. Rapid prototyping with high power fiber lasers

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, R.M. [Faculty of Sciences and Technology, New University Lisbon (Portugal); IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Lopes, G. [Welding Engineering Research Centre, Building 46, Cranfield University, Bedfordshire, MK43 0AL (United Kingdom); Quintino, L. [IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail:; Rodrigues, J.P. [IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Williams, S. [Welding Engineering Research Centre, Building 46, Cranfield University, Bedfordshire, MK43 0AL (United Kingdom)


    Laser rapid prototyping technologies comprise a set of technologies used in a wide range of materials to produce prototypes or small batches of complex shaped components. This paper presents a research work on rapid prototyping technology with laser additive manufacture of wire based alloy Ti-6Al-4V with an 8 kW fiber laser for the production of components with cylindrical geometry. For this, an engineering system was developed, a demonstration part produced and the deposition process was characterized. Two processing parameters were investigated: and these were the relative position between the wire feeding system and the substrate and the laser beam to wire width ratio. The former affects the molten metal transfer mode and the pressure exerted by the wire tip on the molten pool, while the laser beam to wire width ratio affects the process efficiency, since this is a compromise of process stability and process speed. Both parameters control surface finishing and the smoothness of the part. The melting efficiency of the process is low when compared to alternative processes involving powder pre deposition, but the density of the part is improved with homogeneous structural characteristics.

  7. Radial current high power dummy load for characterizing the high power laser triggered transformer-type accelerator. (United States)

    Yin, Yi; Zhong, Hui-Huang; Liu, Jin-Liang; Ren, He-Ming; Yang, Jian-Hua; Zhang, Xiao-Ping; Hong, Zhi-qiang


    A radial-current aqueous resistive solution load was applied to characterize a laser triggered transformer-type accelerator. The current direction in the dummy load is radial and is different from the traditional load in the axial. Therefore, this type of dummy load has smaller inductance and fast response characteristic. The load was designed to accommodate both the resistance requirement of accelerator and to allow optical access for the laser. Theoretical and numerical calculations of the load's inductance and capacitance are given. The equivalent circuit of the dummy load is calculated in theory and analyzed with a PSPICE code. The simulation results agree well with the theoretical analysis. At last, experiments of the dummy load applied to the high power spiral pulse forming line were performed; a quasisquare pulse voltage is obtained at the dummy load.

  8. Beam Delivery Systems For High Power Lasers (United States)

    Hohberg, G.


    For materials processing with lasers, beam delivery systems are necessary for directing the radiation from the laser head to the working point on the workpiece. The more new fields of application are assumed by the laser, the greater the need for beam delivery systems which have been appropriately designed to meet the requirements of the task to be performed. Depending on the task on hand the appropriate design may be a fixed pipe with a focussing lens at its end or a six-axis articulated arm. This paper will describe the design principles and their optical and mechanical properties. The discussion of the advantages and disadvantages may be of some help in choosing an adequate delivery system.

  9. Recent results in mirror based high power laser cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Nielsen, Jakob Skov; Elvang, Mads


    In this paper, recent results in high power laser cutting, obtained in reseach and development projects are presented. Two types of mirror based focussing systems for laser cutting have been developed and applied in laser cutting studies on CO2-lasers up to 12 kW. In shipyard environment cutting...... speed increase relative to state-of-the-art cutting of over 100 % has been achieved....

  10. Atmospheric propagation and combining of high-power lasers. (United States)

    Nelson, W; Sprangle, P; Davis, C C


    In this paper, we analyze beam combining and atmospheric propagation of high-power lasers for directed-energy (DE) applications. The large linewidths inherent in high-power fiber and slab lasers cause random phase and intensity fluctuations that occur on subnanosecond time scales. Coherently combining these high-power lasers would involve instruments capable of precise phase control and operation at rates greater than ∼10  GHz. To the best of our knowledge, this technology does not currently exist. This presents a challenging problem when attempting to phase lock high-power lasers that is not encountered when phase locking low-power lasers, for example, at milliwatt power levels. Regardless, we demonstrate that even if instruments are developed that can precisely control the phase of high-power lasers, coherent combining is problematic for DE applications. The dephasing effects of atmospheric turbulence typically encountered in DE applications will degrade the coherent properties of the beam before it reaches the target. Through simulations, we find that coherent beam combining in moderate turbulence and over multikilometer propagation distances has little advantage over incoherent combining. Additionally, in cases of strong turbulence and multikilometer propagation ranges, we find nearly indistinguishable intensity profiles and virtually no difference in the energy on the target between coherently and incoherently combined laser beams. Consequently, we find that coherent beam combining at the transmitter plane is ineffective under typical atmospheric conditions.

  11. High-power laser source evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Decker, C.D.; Dipeso, G.J.; Gerassimenko, M.; Managan, R.A.; Serduke, F.J.D.; Simonson, G.F.; Suter, L.J.



  12. Support for High Power Laser Ablation 2010 (United States)


    Spaces from the Ministry of Education, Culture, Sport , Science and Technology, Japan. 27 [24] An Analytical Model of Ablation in Gas Flow Leonid...Targets at 0.1-10 TW/cm2 John L. Remo Dept. of Astronomy and Dept. of Earth and Planetary Sciences, Harvard University, 20 Oxford St. and Harvard...modeling of planetary cores and high velocity impact. [43] Laser and Z-pinch Simulation of High Energy Density Planetary Interactions John L. Remo

  13. Laser Cooled High-Power Fiber Amplifier


    Nemova, Galina


    A theoretical model for laser cooled continuous-wave fiber amplifier is presented. The amplification process takes place in the Tm3+-doped core of the fluoride ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber. The cooling process takes place in the Yb3+:ZBLAN fiber cladding. It is shown that for each value of the pump power and the amplified signal there is a distribution of the concentration of the Tm3+ along the length of the fiber amplifier, which provides its athermal operation. The influence ...

  14. Functionally graded materials produced with high power lasers

    NARCIS (Netherlands)

    De Hosson, JTM; Ocelík, Vašek; Chandra, T; Torralba, JM; Sakai, T


    In this keynote paper two examples will be present of functionally graded materials produced with high power Nd:YAG lasers. In particular the conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of A18Si and Ti6Al4V alloys are presented. The formation of

  15. In-situ strain observation in high power laser cladding

    NARCIS (Netherlands)

    Ocelik, V.; Bosgra, J.; de Hosson, J. Th. M.


    The modern experimental technique - so called Digital Image Correlation - is applied during high power laser surface treatments for in-situ observation of displacements and strains near the processing area during and a short time after laser processing. An experimental setup has been designed and

  16. Device for wavefront correction in an ultra high power laser (United States)

    Ault, Earl R.; Comaskey, Brian J.; Kuklo, Thomas C.


    A system for wavefront correction in an ultra high power laser. As the laser medium flows past the optical excitation source and the fluid warms its index of refraction changes creating an optical wedge. A system is provided for correcting the thermally induced optical phase errors.

  17. All solid-state high power visible laser (United States)

    Grossman, William M.


    The overall objective of this Phase 2 effort was to develop and deliver to NASA a high repetition rate laser-diode-pumped solid-state pulsed laser system with output in the green portion of the spectrum. The laser is for use in data communications, and high efficiency, short pulses, and low timing jitter are important features. A short-pulse 1 micron laser oscillator, a new multi-pass amplifier to boost the infrared power, and a frequency doubler to take the amplified infrared pulsed laser light into the green. This produced 1.5 W of light in the visible at a pulse repetition rate of 20 kHz in the laboratory. The pulses have a full-width at half maximum of near 1 ns. The results of this program are being commercialized.

  18. High power laser-matter interaction

    CERN Document Server

    Mulser, Peter


    This book intended as a guide for scientists and students who have just discovered the field as a new and attractive area of research, and for scientists who have worked in another field and want to join now the subject of laser plasmas. In the first chapter the plasma dynamics is described phenomenologically by a two fluid model and similarity relations from dimensional analysis. Chapter 2 is devoted to plasma optics and collisional absorption in the dielectric and ballistic model. Linear resonance absorption at the plasma frequency and its mild nonlinearities as well as the self-quenching of high amplitude electron plasma waves by wave breaking are discussed in Chapter 3. With increasing laser intensity the plasma dynamics is dominated by radiation pressure, at resonance producing all kinds of parametric instabilities and out of resonance leading to density steps, self-focusing and filamentation, described in Chapters 4 and 5. A self-contained treatment of field ionization of atoms and related phenomena ar...

  19. Developing high-power hybrid resonant gain-switched thulium fiber lasers. (United States)

    Yan, Shuo; Wang, Yao; Zhou, Yan; Yang, Nan; Li, Yue; Tang, Yulong; Xu, Jianqiu


    In this paper, we propose hybrid-pumped resonant gain-switched thulium fiber lasers to realize high-average-power and high-pulse-energy 2-μm laser emissions. Based on numerical simulation, laser dynamics (pulse peak power, pulse energy, pulse duration, etc.) of this kind of laser system are investigated in detail. By taking advantages of the 793 nm continuous wave pump and the 1900 nm pulsed pump, performance of the laser emission can be significantly improved, with the highest average power of 28 W, peak power of 3.5 kW, pulse energy of 281 μJ, and narrowest pulse duration of 92 ns, all of which can be further optimized through designing the cavity parameters and the pumping circumstance. Compared with the pump pulses, two times improvement in pulse energy and average power has been achieved. This hybrid resonant gain-switched system has an all-fiber configuration and high efficiency (low heat load), and can be steadily extended into the cladding pump scheme, thus paving a new way to realize high power (>100 W average power) and high pulse energy (>1 mJ) 2 μm thulium fiber lasers.

  20. High-power green diode laser systems for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André

    in conjunction with optical coherence tomography, two-photon microscopy or coherent anti-Stokes Raman scattering microscopy. In order to provide high-power green diode laser emission, nonlinear frequency conversion of state-of-the-art near-infrared diode lasers represents a necessary means. However, the obtained....... The underlying principle is spectral beam combining of multiple, comparable diode lasers with subsequent nonlinear frequency conversion. In the former approach multiple lasers are incoherently combined with an external optical component. With two 1062 nm tapered diode lasers and a reflecting volume Bragg grating...

  1. Coherent beam combiner for a high power laser (United States)

    Dane, C. Brent; Hackel, Lloyd A.


    A phase conjugate laser mirror employing Brillouin-enhanced four wave mixing allows multiple independent laser apertures to be phase locked producing an array of diffraction-limited beams with no piston phase errors. The beam combiner has application in laser and optical systems requiring high average power, high pulse energy, and low beam divergence. A broad range of applications exist in laser systems for industrial processing, especially in the field of metal surface treatment and laser shot peening.

  2. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian


    We demonstrated robust and bend insensitive fiber delivery of high power laser with diffraction limited beam quality for two different kinds of hollow core band gap fibers. The light source for this experiment consists of ytterbium-doped double clad fiber aeroGAIN-ROD-PM85 in a high power amplifier...... setup. It provided 22ps pulses with a maximum average power of 95W, 40MHz repetition rate at 1032nm (~2.4μJ pulse energy), with M2 power output for a 5 meters fiber. The damage...... threshold for a 19-cell hollow core photonic bandgap fiber exceeded the maximum power provided by the light source and up to 76W average output power was demonstrated for a 1m fiber. In both cases, no special attention was needed to mitigate bend sensitivity. The fibers were coiled on 8 centimeters radius...

  3. Flyer acceleration experiments using high-power laser

    Directory of Open Access Journals (Sweden)

    Kadono T.


    Full Text Available Flyer acceleration technique using high-power lasers has several advantages such as the achieved velocities higher than 10 km/s and non-contamination to the products generated by impacts. In this study, we show that a high-power laser can achieve flyer velocities higher than 10 km/s up to 60 km/s using spherical projectiles with a diameter of 0.1 − 0.3mm. We discuss the projectile condition during the flight based on the results of numerical simulations.

  4. Material Processing with High Power CO2-Lasers (United States)

    Bakowsky, Lothar


    After a period of research and development lasertechnique now is regarded as an important instrument for flexible, economic and fully automatic manufacturing. Especially cutting of flat metal sheets with high power C02-lasers and CNC controlled two or three axes handling systems is a wide spread. application. Three dimensional laser cutting, laser-welding and -heat treatment are just at the be ginning of industrial use in production lines. The main. advantages of laser technology. are - high. accuracy - high, processing velocity - law thermal distortion. - no tool abrasion. The market for laser material processing systems had 1985 a volume of 300 Mio S with growth rates between, 20 % and 30 %. The topic of this lecture are hiTrh. power CO2-lasers. Besides this systems two others are used as machining tools, Nd-YAG- and Eximer lasers. All applications of high. power CO2-lasers to industrial material processing show that high processing velocity and quality are only guaranteed in case of a stable intensity. profile on the workpiece. This is only achieved by laser systems without any power and mode fluctuations and by handling systems of high accuracy. Two applications in the automotive industry are described, below as examples for laser cutting and laser welding of special cylindrical motor parts.

  5. Collisionless dissociation and isotopic enrichment of SF6 using high-powered CO2 laser radiation (United States)

    Gower, M. C.; Billman, K. W.


    Dissociation of S-32F6 and the resultant isotopic enrichment of S-34F6 using high-powered CO2 laser radiation has been studied with higher experimental sensitivity than previously reported. Enrichment factors have been measured as a function of laser pulse number, wavelength, energy and time duration. A geometry independent dissociation cross section is introduced and measured values are presented. Threshold energy densities, below which no dissociation was observed, were also determined.

  6. Study of the high power laser-metal interactions in the gaseous atmospheres (United States)

    Lugomer, Stjepan; Bitelli, G.; Stipancic, M.; Jovic, F.


    The tantalum and titanium plates were treated by pulsed, high power CO2 laser in the pressurized atmospheres of N2 and O2. Studies performed by the optical microscopy, microhardness measurements, and the auger electron spectroscopy revealed: (1) topographic modification of the surface caused by the temperature field; (2) metal hardening, caused by the laser shock; and (3) alloying/cladding, caused by the chemical reaction between the metal surface and the gaseous atmosphere.

  7. High power composite cavity fiber laser oscillator at 1120 nm (United States)

    Wang, Jianming; Li, Cheng; Yan, Dapeng


    A high power composite cavity fiber laser oscillator at 1120 nm is demonstrated experimentally. Performances of the 1120 nm single fiber laser oscillator and the composite cavity are investigated and compared, and the parasitic oscillation created by the strong amplified spontaneous emission (ASE) can be suppressed effectively in the composite cavity scheme. 2.04-kW 1120-nm signal light with a good beam quality (M2=1.15) is obtained, and the optical conversion efficiency of the composite cavity fiber laser oscillator is about 63% in the experiment. The compact architecture of composite cavity provides an effective scheme for power scaling of long wavelength lasers.

  8. High-Power ZBLAN Glass Fiber Lasers: Review and Prospect

    Directory of Open Access Journals (Sweden)

    Xiushan Zhu


    Full Text Available ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF, considered as the most stable heavy metal fluoride glass and the excellent host for rare-earth ions, has been extensively used for efficient and compact ultraviolet, visible, and infrared fiber lasers due to its low intrinsic loss, wide transparency window, and small phonon energy. In this paper, the historical progress and the properties of fluoride glasses and the fabrication of ZBLAN fibers are briefly described. Advances of infrared, upconversion, and supercontinuum ZBLAN fiber lasers are addressed in detail. Finally, constraints on the power scaling of ZBLAN fiber lasers are analyzed and discussed. ZBLAN fiber lasers are showing promise of generating high-power emissions covering from ultraviolet to mid-infrared considering the recent advances in newly designed optical fibers, beam-shaped high-power pump diodes, beam combining techniques, and heat-dissipating technology.

  9. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization. (United States)

    Caccianiga, Gianluigi; Baldoni, Marco; Ghisalberti, Carlo Angelo; Paiusco, Alessio


    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL(+) ™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis.

  10. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT: Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization

    Directory of Open Access Journals (Sweden)

    Gianluigi Caccianiga


    Full Text Available Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT: such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy combined with hydrogen peroxide, comparing a pulsed diode laser (LI activity to a high-frequency superpulsed diode laser (LII. Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL+™ Solution (hydrogen peroxide (HP stabilized with a glycerol phosphate complex. Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis.

  11. The interaction of high-power lasers with plasmas

    CERN Document Server

    Eliezer, Shalom


    The Interaction of High-Power Lasers with Plasmas provides a thorough self-contained discussion of the physical processes occurring in laser-plasma interactions, including a detailed review of the relevant plasma and laser physics. The book analyzes laser absorption and propagation, electron transport, and the relevant plasma waves in detail. It also discusses the physics of the electric and magnetic fields in a laser-induced plasma medium, laser-induced shock waves, rarefaction waves, heat waves, and the related hydrodynamic instabilities (Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-Helmholtz).A pedagogical presentation, the book addresses the basic physics issues from first principles, using simple models wherever appropriate. The coverage provides a foundation on which the graduate student can build an understanding of the past and present research in this field. For the experienced researcher, the book is a comprehensive and useful presentation of laser-plasma interactions.

  12. High Power laser power conditioning system new discharge circuit research

    CERN Document Server

    Li Yi; Peng Han Sheng; Zhou Pei Zhang; Zheng Wan Guo; Guo Lang Fu; Chen Li Hua; Chen De Hui; Lai Gui You; Luan Yong Ping


    The new discharge circuit of power conditioning system for high power laser is studied. The theoretical model of the main discharge circuit is established. The pre-ionization circuit is studied in experiment. In addition, the explosion energy of the new large xenon lamp is successfully measured. The conclusion has been applied to 4 x 2 amplifier system

  13. Ignition studies in support of the European High Power Laser ...

    Indian Academy of Sciences (India)

    The European High Power Laser Energy Research Facility (HiPER) project is one of a number of large-scale scientific infrastructure projects supported by the European Commission's Seventh Framework Programme (FP7). Part of this project involves the development of a target area for the exploration of inertial fusion ...

  14. Long distance high power optical laser fiber break detection and continuity monitoring systems and methods (United States)

    Rinzler, Charles C.; Gray, William C.; Faircloth, Brian O.; Zediker, Mark S.


    A monitoring and detection system for use on high power laser systems, long distance high power laser systems and tools for performing high power laser operations. In particular, the monitoring and detection systems provide break detection and continuity protection for performing high power laser operations on, and in, remote and difficult to access locations.

  15. High SBS-Threshold Er/Yb Co-Doped Phosphate Glass Fiber Amplifiers for High Power, Sub-us Pulsed, Narrow Linewidth, All Fiber-Based Laser Transmitter Project (United States)

    National Aeronautics and Space Administration — In Phase I, NP Photonics has achieved 1.2 kW peak power for 105 ns fiber laser pulses, and successfully demonstrated the feasibility to produce monolithic high SBS...

  16. Coherent combination of high-power, zigzag slab lasers (United States)

    Goodno, G. D.; Komine, H.; McNaught, S. J.; Weiss, S. B.; Redmond, S.; Long, W.; Simpson, R.; Cheung, E. C.; Howland, D.; Epp, P.; Weber, M.; McClellan, M.; Sollee, J.; Injeyan, H.


    We demonstrate a scalable architecture for a high-power, high-brightness, solid-state laser based on coherent combinations of master oscillator power amplifier chains. A common master oscillator injects a sequence of multikilowatt Nd:YAG zigzag slab amplifiers. Adaptive optics correct the wavefront of each amplified beamlet. The beamlets are tiled side by side and actively phase locked to form a single output beam. The laser produces 19 kW with beam quality <2× diffraction limited. To the best of our knowledge, this is the brightest cw solid-state laser demonstrated to date.

  17. Highly-efficient high-power pumps for fiber lasers (United States)

    Gapontsev, V.; Moshegov, N.; Berezin, I.; Komissarov, A.; Trubenko, P.; Miftakhutdinov, D.; Berishev, I.; Chuyanov, V.; Raisky, O.; Ovtchinnikov, A.


    We report on high efficiency multimode pumps that enable ultra-high efficiency high power ECO Fiber Lasers. We discuss chip and packaged pump design and performance. Peak out-of-fiber power efficiency of ECO Fiber Laser pumps was reported to be as high as 68% and was achieved with passive cooling. For applications that do not require Fiber Lasers with ultimate power efficiency, we have developed passively cooled pumps with out-of-fiber power efficiency greater than 50%, maintained at operating current up to 22A. We report on approaches to diode chip and packaged pump design that possess such performance.

  18. Status and future prospects of laser fusion and high power laser applications (United States)

    Mima, Kunioki


    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

  19. High-power thulium lasers on a silicon photonics platform. (United States)

    Li, Nanxi; Purnawirman, P; Su, Zhan; Salih Magden, E; Callahan, Patrick T; Shtyrkova, Katia; Xin, Ming; Ruocco, Alfonso; Baiocco, Christopher; Ippen, Erich P; Kärtner, Franz X; Bradley, Jonathan D B; Vermeulen, Diedrik; Watts, Michael R


    Mid-infrared laser sources are of great interest for various applications, including light detection and ranging, spectroscopy, communication, trace-gas detection, and medical sensing. Silicon photonics is a promising platform that enables these applications to be integrated on a single chip with low cost and compact size. Silicon-based high-power lasers have been demonstrated at 1.55 μm wavelength, while in the 2 μm region, to the best of our knowledge, high-power, high-efficiency, and monolithic light sources have been minimally investigated. In this Letter, we report on high-power CMOS-compatible thulium-doped distributed feedback and distributed Bragg reflector lasers with single-mode output powers up to 267 and 387 mW, and slope efficiencies of 14% and 23%, respectively. More than 70 dB side-mode suppression ratio is achieved for both lasers. This work extends the applicability of silicon photonic microsystems in the 2 μm region.

  20. High power and single mode quantum cascade lasers. (United States)

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


    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.

  1. High power 1060-nm super large vertical cavity semiconductor lasers (United States)

    Tan, Shaoyang; Zhai, Teng; Wang, Wei; Zhang, Ruikang; Lu, Dan; Ji, Chen


    High power single-mode ridge waveguide 1060-nm semiconductor lasers are reported. The lasers consist of compressively strained double InGaAs/GaAs quantum wells and a GaAs/AlGaAs separate confinement vertical structure. A super large vertical optical cavity is employed to have a low internal loss, large optical spot size and low vertical optical divergence angle. The material composition and thickness of waveguide layers and claddings layer are optimized systematically. The active layer is detuned from center of the waveguide and thickness of cladding layers is optimized to guaranty single mode lasing of the large optical cavity. The large vertical cavity laser structure with thickness of 4 μm allows the lasers have a low internal loss of less than 0.6 /cm, a large optical spot size about 1μm and a vertical divergence angle about 20 degree. For lateral optical confinement, a double trench ridge waveguide is employed to maintain single-lateral-mode operation. Based on the optimization, 1.5 W continue wave optical power is achieved for broad area lasers with 1mm longitude cavity length. Narrow stripe ridge waveguide lasers of 1mm cavity length with single mode current and optical power of 700 mA and 340 mW is obtained. Suggestions for further improvements in terms of single mode power and applications of the high power semiconductors are discussed.

  2. Development of adaptive resonator techniques for high-power lasers

    Energy Technology Data Exchange (ETDEWEB)

    An, J; Brase, J; Carrano, C; Dane, C B; Flath, L; Fochs, S; Hurd, R; Kartz, M; Sawvel, R


    The design of an adaptive wavefront control system for a high-power Nd:Glass laser will be presented. Features of this system include: an unstable resonator in confocal configuration, a multi-module slab amplifier, and real-time intracavity adaptive phase control using deformable mirrors and high-speed wavefront sensors. Experimental results demonstrate the adaptive correction of an aberrated passive resonator (no gain).

  3. Active beam integrator for high power coherent lasers

    Energy Technology Data Exchange (ETDEWEB)

    Laguarta, F.; Armengol, J.; Vega, F.; Lupon, N. [Univ. Politecnica de Catalunya, Terrassa (Spain). Dept. d`Optica i Optometria


    In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. The authors have designed and tested a very simple beam shaper for transforming the initial intensity distribution of a CO{sub 2} laser beam mode into a more uniform intensity profile. The beam shaper is a two-faceted mirror for active integration of high power coherent laser beams. After reflection in the faceted mirror, a TEM00 or TEM01 CO{sub 2} laser beam is divided into two beamlets that overlap to give a more uniform intensity distribution. A sharp interference pattern due to the high spatial coherence of the incident beam appears. This interference pattern is actively integrated by a high-frequency longitudinal displacement of one of the facets. This provides a change in the relative phase of the two beamlets, and consequently the interference pattern vibrates and its contribution to the intensity distribution averages out. When sweeping this distribution over a sample, a uniform amount of energy is deposited at every point of its surface. It must be emphasized that unlike multifaceted mirrors, the two-facet integrator may provide uniform intensity profiles over any working distance. Finally, as in other integration devices an imaging system may be used to obtain a spot of the shape and the size desired for a particular application.

  4. High-Power Lasers for Science and Society

    Energy Technology Data Exchange (ETDEWEB)

    Siders, C. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Haefner, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Since the first demonstration of the laser in 1960 by Theodore Maiman at Hughes Research Laboratories, the principal defining characteristic of lasers has been their ability to focus unprecedented powers of light in space, time, and frequency. High-power lasers have, over the ensuing five and a half decades, illuminated entirely new fields of scientific endeavor as well as made a profound impact on society. While the United States pioneered lasers and their early applications, we have been eclipsed in the past decade by highly effective national and international networks in both Europe and Asia, which have effectively focused their energies, efforts, and resources to achieve greater scientific and societal impact. This white paper calls for strategic investment which, by striking an appropriate balance between distributing our precious national funds and establishing centers of excellence, will ensure a broad pipeline of people and transformative ideas connecting our world-leading universities, defining flagship facilities stewarded by our national laboratories, and driving innovation across industry, to fully exploit the potential of high-power lasers.

  5. High-power disk lasers based on dilute nitride heterostructures (United States)

    Guina, M.; Leinonen, T.; Härkönen, A.; Pessa, M.


    We report the development of InGaAsN-based gain mirrors for high-power optically pumped semiconductor disk lasers with direct emission at wavelengths around 1180 nm. The gain mirrors were fabricated by molecular beam epitaxy. They consist of 10 dilute nitride quantum wells, which were placed within a GaAs micro-cavity on top of a GaAs/AlAs distributed Bragg reflector. We demonstrated laser operation at ~1180 nm with record high output power (~7 W). The differential efficiency was ~30% for operation at 5 °C and ~28% when operating at 15 °C. The lasers exhibited excellent tuning characteristics, delivering an output power of more than 5 W in a narrow spectrum and providing over 30 nm tuning band. These features represent significant progress towards demonstration of practical high-power lasers with frequency-doubled yellow emission required for laser guide stars, life sciences and spectroscopy. At the same time the results emphasize the importance of dilute nitride heterostructures in the development of novel optoelectronic devices.

  6. High Power, Repetitive, Stacked Blumlein Pulse Generators Commuted by a Single Switching Element (United States)

    Bhawalkar, Jayant Dilip

    In this work, the stacked Blumlein pulsers developed at the University of Texas at Dallas were characterized and shown to be versatile sources of pulse power for a variety of applications. These devices consisted of several triaxial Blumleins stacked in series at one end. The lines were charged in parallel and synchronously commuted repetitively with a single switching element at the other end. In this way, relatively low charging voltages were multiplied to give a high discharge voltage across an arbitrary load without the need for complex Marx bank circuitry. Several pulser parameters such as the number of stacked Blumlein lines, line configuration, type of switching element, and the length of the lines, were varied and the waveform characteristics were observed and analyzed. It was shown that these devices are capable of generating fast rising waveforms with a wide range of peak voltage and current values. The generation of high power waveforms with pulse durations in the range of 80-600 ns was demonstrated without degradation of the voltage gains. The results of this work indicated that unlike generators based on stacked transmission lines, the effects of parasitic modes were not appreciable for the stacked Blumlein pulsers. Opportunities for tactically packaging these pulsers were also investigated and a significant reduction in their size and weight was demonstrated. For this, dielectric lifetime and Blumlein spacing studies were performed on small scale prototypes. In addition to production of intense X-ray pulses, the possible applications for these novel pulsers include driving magnetrons for high power microwave generation, pumping laser media, or powering e-beam diodes. They could also serve as compact, tabletop sources of high power pulses for various research experiments.

  7. High-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power. (United States)

    Rudin, B; Wittwer, V J; Maas, D J H C; Hoffmann, M; Sieber, O D; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U


    High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser.

  8. Coherent beam combining architectures for high power tapered laser arrays (United States)

    Schimmel, G.; Janicot, S.; Hanna, M.; Decker, J.; Crump, P.; Erbert, G.; Witte, U.; Traub, M.; Georges, P.; Lucas-Leclin, G.


    Coherent beam combining (CBC) aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. We have investigated the CBC of an array of five individually-addressable high-power tapered laser diodes at λ = 976 nm, in two architectures: the first one utilizes the self-organization of the lasers in an interferometric extended-cavity, which ensures their mutual coherence; the second one relies on the injection of the emitters by a single-frequency laser diode. In both cases, the coherent combining of the phase-locked beams is ensured on the front side of the array by a transmission diffractive grating with 98% efficiency. The passive phase-locking of the laser bar is obtained up to 5 A (per emitter). An optimization algorithm is implemented to find the proper currents in the five ridge sections that ensured the maximum combined power on the front side. Under these conditions we achieve a maximum combined power of 7.5 W. In the active MOPA configuration, we can increase the currents in the tapered sections up to 6 A and get a combined power of 11.5 W, corresponding to a combining efficiency of 76%. It is limited by the beam quality of the tapered emitters and by fast phase fluctuations between emitters. Still, these results confirm the potential of CBC approaches with tapered lasers to provide a high-power and high-brightness beam, and compare with the current state-of-the-art with laser diodes.

  9. Multi-focus beam shaping of high power multimode lasers (United States)

    Laskin, Alexander; Volpp, Joerg; Laskin, Vadim; Ostrun, Aleksei


    Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from "inverseGauss" intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

  10. High-power diode lasers and their direct industrial applications (United States)

    Loosen, Peter; Treusch, Hans-Georg; Haas, C. R.; Gardenier, U.; Weck, Manfred; Sinnhoff, V.; Kasperowski, S.; vor dem Esche, R.


    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.

  11. Quality and performance of laser cutting with a high power SM fiber laser

    DEFF Research Database (Denmark)

    Kristiansen, Morten; Selchau, Jacob; Olsen, F. O.


    The introduction of high power single mode fiber lasers allows for a beam of high power and a good beam quality factor (M2 ” 1.2), compared to the multimode fiber lasers often utilised in macro laser metal cutting. This paper describes fundamental studies of macro laser metal cutting with a single...... mode fiber laser to study the performance of such lasers in terms of cut quality and process performance. Linear cut experiments have been performed applying a 3kW single mode fiber laser and varying the following parameters: laser power, cutting speed, focal length, focus position, cutting gas...... influence the cut quality and the maximum cutting speed in the investigated parameter space. Furthermore the achieved cutting performance is benchmarked to laser cutting with other types of lasers, CO2-lasers, disc-lasers as well as multimode fiber lasers....

  12. High-Power Fiber Lasers Using Photonic Band Gap Materials (United States)

    DiDomenico, Leo; Dowling, Jonathan


    High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power

  13. Highly efficient and high-power diode-pumped femtosecond Yb:LYSO laser (United States)

    Tian, Wenlong; Wang, Zhaohua; Zhu, Jiangfeng; Zheng, Lihe; Xu, Jun; Wei, Zhiyi


    A diode-pumped high-power femtosecond Yb:LYSO laser with high efficiency is demonstrated. With a semiconductor saturable absorber mirror for passive mode-locking and a Gires-Tournois interferometer mirror for intracavity dispersion compensation, stable mode-locking pulses of 297 fs duration at 1042 nm were obtained. The maximum average power of 3.07 W was realized under 5.17 W absorbed pump power, corresponding to as high as 59.4% opt-opt efficiency. The single pulse energy and peak power are about 35.5 nJ and 119.5 kW, respectively.

  14. Vacuum Window Design for High-Power Lasers

    CERN Document Server

    Shaftan, T V


    One of the problems in the high-power lasers design is in outcoupling of a powerful laser beam out of a vacuum volume into atmosphere. Usually the laser device is located inside a vacuum tank. The laser radiation is transported to the outside world through the transparent vacuum window. While considered transparent, some of the light passing through the glass is absorbed and converted to heat. For most applications, these properties are academic curiosities; however, in multi-kilowatt lasers, the heat becomes significant and can lead to a failure. The absorbed power can result in thermal stress, reduction of light transmission and, consequently, window damage. Modern optical technology has developed different types of glass (Silica, BK7, diamond, etc.) that have high thermal conductivity and damage threshold. However, for kilo- and megawatt lasers the issue still remains open. In this paper we present a solution that may relieve the heat load on the output window. We discuss advantages and issues of this part...

  15. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude


    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  16. High power continuous-wave dual-wavelength alexandrite laser (United States)

    Ghanbari, Shirin; Major, Arkady


    A high power dual-wavelength alexandrite (Cr:BeAl2O4) laser using a single plate birefringent filter (BRF) was demonstrated. Using a 6 mm thick BRF, dual-wavelength output at 745.2 nm and 756.2 nm (5.9 THz of frequency difference) with 850 mW of average output power was achieved as well as with 16.8% optical-to-optical and 24.2% slope efficiency. The tunability of dual-wavelength separation was also demonstrated by employing the 4 mm and 2 mm thick BRFs with similar output powers. To the best of our knowledge, this is the first demonstration of a dual-wavelength alexandrite laser.

  17. High-power laser experiments to study collisionless shock generation

    Directory of Open Access Journals (Sweden)

    Sakawa Y.


    Full Text Available A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  18. Control system for high power laser drilling workover and completion unit (United States)

    Zediker, Mark S; Makki, Siamak; Faircloth, Brian O; DeWitt, Ronald A; Allen, Erik C; Underwood, Lance D


    A control and monitoring system controls and monitors a high power laser system for performing high power laser operations. The control and monitoring system is configured to perform high power laser operation on, and in, remote and difficult to access locations.

  19. High power continuous-wave titanium:sapphire laser (United States)

    Erbert, Gaylen V.; Bass, Isaac L.; Hackel, Richard P.; Jenkins, Sherman L.; Kanz, Vernon K.; Paisner, Jeffrey A.


    A high-power continuous-wave laser resonator (10) is provided, wherein first, second, third, fourth, fifth and sixth mirrors (11-16) form a double-Z optical cavity. A first Ti:Sapphire rod (17) is disposed between the second and third mirrors (12,13) and at the mid-point of the length of the optical cavity, and a second Ti:Sapphire rod (18) is disposed between the fourth and fifth mirrors (14,15) at a quarter-length point in the optical cavity. Each Ti:Sapphire rod (17,18) is pumped by two counter-propagating pump beams from a pair of argon-ion lasers (21-22, 23-24). For narrow band operation, a 3-plate birefringent filter (36) and an etalon (37) are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors (101, 192) are disposed between the first and second mirrors (11, 12) to form a triple-Z optical cavity. A third Ti:Sapphire rod (103) is disposed between the seventh and eighth mirrors (101, 102) at the other quarter-length point in the optical cavity, and is pumped by two counter-propagating pump beams from a third pair of argon-ion lasers (104, 105).

  20. High-power lasers for directed-energy applications: comment. (United States)

    Vorontsov, Mikhail A; Weyrauch, Thomas


    Sprangle et al. [Appl. Opt.54, F201 (2015)APOPAI0003-693510.1364/AO.54.00F201] recently concluded that our experiments on coherent combining of laser beams over an atmospheric path [Opt. Lett.36, 4455 (2011)OPLEDP0146-959210.1364/OL.36.004455] were "effective only because at these low-power levels the linewidth of the lasers was very narrow… and the level of atmospheric turbulence was low…." These conclusions are inaccurate, not relevant to practical high-power coherently combined laser systems, and contradict our most recent experiments with coherent combining of 21 laser beams with a linewidth of about 1 GHz over 7 km distance. In this comment we also challenge the major conclusion of Sprangle et al. [Appl. Opt.54, F201 (2015)APOPAI0003-693510.1364/AO.54.00F201] and the more recently published paper by Nelson et al. [Appl. Opt.55, 1757 (2016)APOPAI0003-693510.1364/AO.55.001757] regarding inefficiency of coherent beam combining under typical atmospheric conditions.

  1. Broadly tunable high-power operation of an all-solid-state titanium-doped sapphire laser system (United States)

    Steele, T. R.; Gerstenberger, D. C.; Drobshoff, A.; Wallace, R. W.


    Broadly tunable and high-power operation of a Ti-doped sapphire laser is obtained with a diode-laser-pumped frequency-doubled Nd:YAG laser as the pump source. A maximum broadband (FWHM = 25 nm) output pulse energy of 720 microJ at 795 nm in a TEM00 mode is obtained for 1850 microJ of energy of 532-nm pump light. A minimum pulse duration of 7 nsec is obtained from a 40-mm-long cavity. With the use of an intracavity prism, the Ti:sapphire laser is tunable continuously over the 696-1000-nm spectral range (with three different mirror sets).

  2. Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency (United States)

    Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.


    The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (stabilization (0.07 𝑛𝑚 • °𝐶-1), provided by a uniform distributed feedback grating (DFB) introduced by etching and re-growth process techniques, is achievable in high power diode lasers using optical feedback. This paper reports on the development of the diode laser structure and the process techniques required to write the gratings taking into account of the thermal dissipation and optical performances. Performances are particularly determined in terms of experimental electro-optical characterizations. One of the main objectives is to determine the thermal resistance of the complete assembly to ensure the mastering of the diode laser temperature for operating condition. The classical approach to determine junction temperature is based on the infrared thermal camera, the spectral measurement and the pulse electrical method. In our case, we base our measurement on the spectral measurement but this approach is not well adapted to the high power diodes laser studied. We develop a new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high power diodes laser. This crucial

  3. Long pulse, high power operation of the ELISE test facility (United States)

    Wünderlich, D.; Kraus, W.; Fröschle, M.; Riedl, R.; Fantz, U.; Heinemann, B.


    The ion source of the ELISE test facility (0.9×1.0 m2 with an extraction area of 0.1 m2) has half the size of the ion source foreseen for the ITER NBI beam lines. Aim of ELISE is to demonstrate that such large RF driven negative ion sources can achieve the following parameters at a filling pressure of 0.3 Pa and for pulse lengths of up to one hour: extracted current densities of 28.5 mA/cm2 in deuterium and 33.0 mA/cm2 in hydrogen, a ratio of co-extracted electrons to extracted ions below one and deviations in the uniformity of the extracted beam of less than 10 %. From the results obtained at ELISE so far it can be deduced that for demonstrating the ITER parameters, an RF power of 80 kW/driver will be necessary, i.e. final aim is to demonstrate long pulses (up to one hour) at this power level and a stable source performance. The most crucial factor limiting the source performance during such pulses - in particular in deuterium - is a steady increase in the co-extracted electron current. This paper reports measures that counteract this steady increase, namely applying a dedicated long pulse caesium conditioning technique and modifying the filter field topology by adding strengthening external permanent magnets. Additionally, RF issues are discussed that prevented increasing the RF power towards the target value. Although it was not possible up to now to perform long pulses at 80 kW/driver, a significant improvement of the source performance and its stability are demonstrated. The latter allowed performing the very first 1 h deuterium pulse in ELISE.

  4. Compact, Low-Cost, Frequency-Locked Semiconductor Laser for Injection Seeding High Power Laser Project (United States)

    National Aeronautics and Space Administration — This NASA Small Business Innovative Research Phase II project will develop a compact, low-cost, wavelength locked seed laser for injection locking high powered...

  5. A Waveguide Based, High Power Pockels Cell Modulator for Sub-Nanosecond Pulse Slicing Project (United States)

    National Aeronautics and Space Administration — The Goal of this STTR is to develop a high speed, high power, waveguide based modulator (phase and amplitude) and investigate its use as a pulse slicer. The key...

  6. Adaptive metal mirror for high-power CO2 lasers (United States)

    Jarosch, Uwe-Klaus


    Spherical mirrors with a variable radius of curvature are used inside laser resonators as well as in the beam path between the laser and the workpiece. Commercially-available systems use piezoelectric actuators, or the pressure of the coolant, to deform the mirror surface. In both cases, the actuator and the cooling system influence each other. This interaction is avoided through the integration of the cooling system with the flexible mirror membrane. A multi- channel design leads to an optimized cooling effect, which is necessary for high power applications. The contour of the variable metal mirror depends on the mounting between the membrane and the mirror body and on the distribution of forces. Four cases of deformation can be distinguished for a circular elastic membrane. The realization of an adaptive metal mirror requires a technical compromise to be made. A mechanical construction is presented which combines an elastic hinge with the inlet and outlet of the coolant. For the deformation of the mirror membranes two actuators with different character of deformation are used. The superposition of the two deformations results in smaller deviations from the spherical surface shape than can be achieved using a single actuator. DC proportional magnets have been introduced as cheap and rigid actuators. The use of this adaptive mirror, either in a low pressure atmosphere of a gas laser resonator, or in an extra-cavity beam path is made possible through the use of a ventilation system.

  7. High Altitude Electromagnetic Pulse (HEMP) and High Power Microwave (HPM) Devices: Threat Assessments (United States)


    against HEMP effects resulting from a nuclear exchange.40 The Limited Test Ban Treaty of 1963 prohibits nuclear explosions in the atmosphere, in space, and...Order Code RL32544 High Altitude Electromagnetic Pulse ( HEMP ) and High Power Microwave (HPM) Devices: Threat Assessments Updated July 21, 2008 Clay...2008 to 00-00-2008 4. TITLE AND SUBTITLE High Altitude Electromagnetic Pulse ( HEMP ) and High Power Microwave (HPM) Devices: Threat Assessments 5a

  8. Development of Long Pulse and High Power 170GHz Gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Keishi; Kasugai, Atsushi; Minami, Ryutaro; Takahashi, Koji; Kobayashi, Noriyuki [Plasma heating Laboratory, Japan Atomic Energy Research Institute (JAERI), 801-1 Mukoyama, Naka-machi, Ibaraki-ken, 311-0193 (Japan)


    Recent activities on the research and development of 170 GHz gyrotron were presented. In the 170 GHz gyrotron experiment in JAERI, pulse duration had been limited by the beam current decrease due to the emission cooling of the electron emitter. A preprogramming control of the heater power was introduced to keep the beam current constant and to avoid the oscillation mode shift to a lower mode during the operation. And, a built-in mode converter system was improved to reduce the stray radiation. In the preliminary experiment results of 0.2 MW/480 sec and 0.13 MW/600 sec were obtained. The pulse extension experiment at higher power will be followed. In parallel, a study of the high order mode oscillation was carried out using a short pulse gyrotron ({approx}1 msec). The oscillation mode is TE{sub 31,12}, which allows 1.5 MW level CW operation. A stable oscillation of TE{sub 31,12} was demonstrated at the power of 1.56 MW. The maximum efficiency was 30% at 1 MW output. This result indicates that the high order mode up to the level of TE{sub 31,12} will be acceptable to increase the power or to reduce the heat load on the cavity wall at 1 MW output.

  9. Analysis of High Power/energy Nuclear Pumped Laser/reactor Concepts. (United States)

    Gu, Guoxiang


    The basic principle of direct energy conversion of nuclear energy into coherent radiation (Nuclear-Pumped Laser or NPL) has been established by many experiments. ^{1-3} Because the high energy density available in nuclear fuel permits a high total output with a very low mass, Nuclear-Powered Lasers offer the possibility of being able to operate very high power lasers from a space base. However, the Nuclear-Pumped Laser is not only an interesting research tool, but also an embryonic engineering technology. It is the most important among all the areas of engineering to develop some specific types of nuclear reactors for use with Nuclear-Pumped Lasers. These reactors need to be coupled with the laser system efficiently, and then provide a high energy conversion efficiency. This study will evaluate the reactor engineering from neutronics point of view, while considering the laser electronics and thermodynamics. Four basic reactor concepts designed specifically for nuclear-pumped lasers have been identified in this study, that is, "the thermal reactor laser","the aerosol -core reactor/laser", "the surface-source reactor/laser" and "the flash lamp gas core reactor/laser". The neutronic design of the reactors for geometries and materials appropriate to each of these concepts is examined. The specific properties in neutronics of these reactors are analyzed. The total reactor size and weight for each of these concepts are estimated. Because the feasibility of using nuclear power to produce a laser pulse of short duration and high intensity is of more current interest, this study concludes with some reactor kinetic behavior. The laser systems that would be coupled to these reactors are not discussed in detail. All the calculations are based mainly on one dimensional diffusion and transport theory, using multiple energy groups. These one dimensional calculations have confirmed the feasibility of four basic concepts from a neutronics point of view.

  10. Fiber facet gratings for high power fiber lasers (United States)

    Vanek, Martin; Vanis, Jan; Baravets, Yauhen; Todorov, Filip; Ctyroky, Jiri; Honzatko, Pavel


    We numerically investigated the properties of diffraction gratings designated for fabrication on the facet of an optical fiber. The gratings are intended to be used in high-power fiber lasers as mirrors either with a low or high reflectivity. The modal reflectance of low reflectivity polarizing grating has a value close to 3% for TE mode while it is significantly suppressed for TM mode. Such a grating can be fabricated on laser output fiber facet. The polarizing grating with high modal reflectance is designed as a leaky-mode resonant diffraction grating. The grating can be etched in a thin layer of high index dielectric which is sputtered on fiber facet. We used refractive index of Ta2O5 for such a layer. We found that modal reflectance can be close to 0.95 for TE polarization and polarization extinction ratio achieves 18 dB. Rigorous coupled wave analysis was used for fast optimization of grating parameters while aperiodic rigorous coupled wave analysis, Fourier modal method and finite difference time domain method were compared and used to compute modal reflectance of designed gratings.

  11. Pressure and stress waves in a spallation neutron source mercury target generated by high-power proton pulses

    CERN Document Server

    Futakawa, M; Conrad, H; Stechemesser, H


    The international ASTE collaboration has performed a first series of measurements on a spallation neutron source target at the Alternating Gradient Synchrotron (AGS) in Brookhaven. The dynamic response of a liquid mercury target hit by high-power proton pulses of about 40 ns duration has been measured by a laser Doppler technique and compared with finite elements calculations using the ABAQUS code. It is shown that the calculation can describe the experimental results for at least the time interval up to 100 mu s after the pulse injection. Furthermore, it has been observed that piezoelectric pressure transducers cannot be applied in the high gamma-radiation field of a spallation target.

  12. Micro-scanning mirrors for high-power laser applications in laser surgery (United States)

    Sandner, Thilo; Kimme, Simon; Grasshoff, Thomas; Todt, Ulrich; Graf, Alexander; Tulea, Cristian; Lenenbach, Achim; Schenk, Harald


    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.

  13. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.


    Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

  14. High power diode laser Master Oscillator-Power Amplifier (MOPA) (United States)

    Andrews, John R.; Mouroulis, P.; Wicks, G.


    High power multiple quantum well AlGaAs diode laser master oscillator - power amplifier (MOPA) systems were examined both experimentally and theoretically. For two pass operation, it was found that powers in excess of 0.3 W per 100 micrometers of facet length were achievable while maintaining diffraction-limited beam quality. Internal electrical-to-optical conversion efficiencies as high as 25 percent were observed at an internal amplifier gain of 9 dB. Theoretical modeling of multiple quantum well amplifiers was done using appropriate rate equations and a heuristic model of the carrier density dependent gain. The model gave a qualitative agreement with the experimental results. In addition, the model allowed exploration of a wider design space for the amplifiers. The model predicted that internal electrical-to-optical conversion efficiencies in excess of 50 percent should be achievable with careful system design. The model predicted that no global optimum design exists, but gain, efficiency, and optical confinement (coupling efficiency) can be mutually adjusted to meet a specific system requirement. A three quantum well, low optical confinement amplifier was fabricated using molecular beam epitaxial growth. Coherent beam combining of two high power amplifiers injected from a common master oscillator was also examined. Coherent beam combining with an efficiency of 93 percent resulted in a single beam having diffraction-limited characteristics. This beam combining efficiency is a world record result for such a system. Interferometric observations of the output of the amplifier indicated that spatial mode matching was a significant factor in the less than perfect beam combining. Finally, the system issues of arrays of amplifiers in a coherent beam combining system were investigated. Based upon experimentally observed parameters coherent beam combining could result in a megawatt-scale coherent beam with a 10 percent electrical-to-optical conversion efficiency.

  15. High Power Laser Diode Arrays for 2-Micron Solid State Coherent Lidars Applications (United States)

    Amzajerdian, Farzin; Meadows, Byron; Kavaya, Michael J.; Singh, Upendra; Sudesh, Vikas; Baker, Nathaniel


    Laser diode arrays are critical components of any diode-pumped solid state laser systems, constraining their performance and reliability. Laser diode arrays (LDAs) are used as the pump source for energizing the solid state lasing media to generate an intense coherent laser beam with a high spatial and spectral quality. The solid state laser design and the characteristics of its lasing materials define the operating wavelength, pulse duration, and power of the laser diodes. The pump requirements for high pulse energy 2-micron solid state lasers are substantially different from those of more widely used 1-micron lasers and in many aspects more challenging [1]. Furthermore, the reliability and lifetime demanded by many coherent lidar applications, such as global wind profiling from space and long-range clear air turbulence detection from aircraft, are beyond the capability of currently available LDAs. In addition to the need for more reliable LDAs with longer lifetime, further improvement in the operational parameters of high power quasi-cw LDAs, such as electrical efficiency, brightness, and duty cycle, are also necessary for developing cost-effective 2-micron coherent lidar systems for applications that impose stringent size, heat dissipation, and power constraints. Global wind sounding from space is one of such applications, which is the main driver for this work as part of NASA s Laser Risk Reduction Program. This paper discusses the current state of the 792 nm LDA technology and the technology areas being pursued toward improving their performance. The design and development of a unique characterization facility for addressing the specific issues associated with the LDAs for pumping 2-micron coherent lidar transmitters and identifying areas of technological improvement will be described. Finally, the results of measurements to date on various standard laser diode packages, as well as custom-designed packages with potentially longer lifetime, will be reported.

  16. High power sub-200fs pulse generation from a colliding pulse modelocked VECSEL (United States)

    Laurain, Alexandre; Marah, Declan; Rockmore, Robert; McInerney, John G.; Hader, Jorg; Ruiz Perez, Antje; Koch, Stephan W.; Stolz, Wolfgang; Moloney, Jerome V.


    We present a passive and robust mode-locking scheme for a Vertical External Cavity Surface Emitting Laser (VECSEL).We placed the semiconductor gain medium and the semiconductor saturable absorber mirror (SESAM) strategically in a ring cavity to provide a stable colliding pulse operation. With this cavity geometry, the two counter propagating pulses synchronize on the SESAM to saturate the absorber together. This minimizes the energy lost and creates a transient carrier grating due to the interference of the two beams. The interaction of the two counter-propagating pulses in the SESAM is shown to extend the range of the modelocking regime and to enable higher output power when compared to the conventional VECSEL cavity geometry. In this configuration, we demonstrate a pulse duration of 195fs with an average power of 225mW per output beam at a repetition rate of 2.2GHz, giving a peak power of 460W per beam. The remarkable robustness of the modelocking regime is discussed and a rigorous pulse characterization is presented.

  17. A novel "gain chip" concept for high-power lasers (Conference Presentation) (United States)

    Li, Min; Li, Mingzhong; Wang, Zhenguo; Yan, Xiongwei; Jiang, Xinying; Zheng, Jiangang; Cui, Xudong; Zhang, Xiaomin


    High-power lasers, including high-peak power lasers (HPPL) and high-average power lasers (HAPL), attract much interest for enormous variety of applications in inertial fusion energy (IFE), materials processing, defense, spectroscopy, and high-field physics research. To meet the requirements of high efficiency and quality, a "gain chip" concept is proposed to properly design the pumping, cooling and lasing fields. The gain chip mainly consists of the laser diode arrays, lens duct, rectangle wave guide and slab-shaped gain media. For the pumping field, the pump light will be compressed and homogenized by the lens duct to high irradiance with total internal reflection, and further coupled into the gain media through its two edge faces. For the cooling field, the coolant travels along the flow channel created by the adjacent slabs in the other two edge-face direction, and cool the lateral faces of the gain media. For the lasing field, the laser beam travels through the lateral faces and experiences minimum thermal wavefront distortions. Thereby, these three fields are in orthogonality offering more spatial freedom to handle them during the construction of the lasers. Transverse gradient doping profiles for HPPL and HAPL have been employed to achieve uniform gain distributions (UGD) within the gain media, respectively. This UGD will improve the management for both amplified spontaneous emission (ASE) and thermal behavior. Since each "gain chip" has its own pump source, power scaling can be easily achieved by placing identical "gain chips" along the laser beam axis without disturbing the gain and thermal distributions. To detail our concept, a 1-kJ pulsed amplifier is designed and optical-to-optical efficiency up to 40% has been obtained. We believe that with proper coolant (gas or liquid) and gain media (Yb:YAG, Nd:glass or Nd:YAG) our "gain chip" concept might provide a general configuration for high-power lasers with high efficiency and quality.

  18. 20 W High Efficiency 1550 nm Pulsed Fiber Laser Project (United States)

    National Aeronautics and Space Administration — High peak power short pulsed lasers have been considered to be an enabling technology to build high power transmitters for future deep space high rate space...

  19. High-power diode-pumped Kerr-lens mode-locked bulk Yb:KGW laser. (United States)

    Akbari, Reza; Major, Arkady


    A high-power (>1  W) pure Kerr-lens mode-locked bulk Yb:KGW laser with multimode fiber-coupled diode pumping was demonstrated. The laser delivered 240 fs pulses with 2.3 W of average output power at 86.8 MHz, corresponding to 97 kW of peak power and 26 nJ of pulse energy. The shortest generated pulse duration was 120 fs with 1.2 W of output power. The self-starting regime was also observed with a background continuous-wave component. The laser exhibited more than an order of magnitude higher output power when compared to the previously reported bulk Yb-ion-doped lasers with multimode laser diode pumping systems.

  20. Systems and assemblies for transferring high power laser energy through a rotating junction (United States)

    Norton, Ryan J.; McKay, Ryan P.; Fraze, Jason D.; Rinzler, Charles C.; Grubb, Daryl L.; Faircloth, Brian O.; Zediker, Mark S.


    There are provided high power laser devices and systems for transmitting a high power laser beam across a rotating assembly, including optical slip rings and optical rotational coupling assemblies. These devices can transmit the laser beam through the rotation zone in free space or within a fiber.

  1. General machining concept for producing micro-optics with high-power UV lasers (United States)

    Toenshoff, Hans K.; Overmeyer, Ludger; Ostendorf, Andreas; Wais, Johannes


    The development of new processes for the micro-treatment of material is the basis for increasing integration and miniaturization of mechanical, optical and electronic components. Pulsed high power excimer lasers offer in combination with a micro-machining system, the possibility of manufacturing highly complex components in different materials like ceramics, glass or metals, Because of the increasing number of technical applications, the need for automatic processing has grown in the last few years. While complete working stations are available for Nd:YAG and CO2 lasers, there is a lack for automatic micro-removal with excimer lasers. For complex microstructures like micro- optics, manual programming of the workpiece handling system becomes uneconomic because of the very high number of laser pulses required. Especially for prototypes and small batches where the workpiece geometries change quickly, the development of a universal and automatic machining concept plays a key role for this technology. For this reason, a general machining concept based on excimer laser removal has been realized beginning with the possibility to construct the workpiece geometry by CAD-design tools. A preprocessor allows to calculate the removal volume based on laser specific ablation volumes. The superposition of each laser pulse removal leads to complex 3D surface structures. Moreover, a general movement strategy optimizes the processing speed. For closing the process chain the realized preprocessor automatically generates the necessary NC-data for the implemented CNC-control system. Functionality of this concept has been proven by manufacturing different two and three dimensional micro-structures like micro-optical components.

  2. GaAs Substrates for High-Power Diode Lasers (United States)

    Mueller, Georg; Berwian, Patrick; Buhrig, Eberhard; Weinert, Berndt

    GaAs substrate crystals with low dislocation density (Etch-Pit Density (EPD) ~10^18,^-3) are required for the epitaxial production of high-power diode-lasers. Large-size wafers (= 3 mathrm{in} -> >=3,) are needed for reducing the manufacturing costs. These requirements can be fulfilled by the Vertical Bridgman (VB) and Vertical Gradient Freeze (VGF) techniques. For that purpose we have developed proper VB/VGF furnaces and optimized the thermal as well as the physico-chemical process conditions. This was strongly supported by extensive numerical process simulation. The modeling of the VGF furnaces and processes was made by using a new computer code called CrysVUN++, which was recently developed in the Crystal Growth Laboratory in Erlangen.GaAs crystals with diameters of 2 and 3in were grown in pyrolytic Boron Nitride (pBN) crucibles having a small-diameter seed section and a conical part. Boric oxide was used to fully encapsulate the crystal and the melt. An initial silicon content in the GaAs melt of c (melt) = 3 x10^19,^-3 has to be used in order to achieve a carrier concentration of n = (0.8- 2) x10^18,^-3, which is the substrate specification of the device manufacturer of the diode-laser. The EPD could be reduced to values between 500,^-2 and 50,^-2 with a Si-doping level of 8 x10^17 to 1 x10^18,^-3. Even the 3in wafers have rather large dislocation-free areas. The lowest EPDs ( <100,^-2) are achieved for long seed wells of the crucible.

  3. Experiments with very high-power lasers. Report of a workshop, November 29-30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Leigh, J.; Rice, S. A.; Trainor, R. J.; Bass, M.; Hendricks, R. W.; Reader, J.


    Among possible experiments of general interest in physics are the study of the spectroscopy and cross section measurements of highly ionized species, the study of nuclear conversion processes, vacuum-ultraviolet lasers, multiphoton absorption, and the Kapitza-Dirac effect. Shock waves driven by ultrahigh-power lasers are capable of attaining pressures of the order of 1 to 4 TPa in material targets, providing a means of deriving equation-of-state data under such extreme conditions. Modifications observed in the structures of materials subjected to high-power laser radiation can lead to studies of damage and phase change processes. Classes of useful experiments in this area are given. The x rays produced when a pulse of ultrahigh-power laser radiation is focussed on a target are sufficiently intense to generate diffraction patterns and EXAFS spectra on a nanosecond time scale. A major application of ultrahigh-power lasers to chemistry and biology may consist in such time-resolved diffraction and EXAFS studies of dynamical systems. The laser systems at the National Laser User Facility at the University of Rochester are described. These systems are available to qualified investigators for user experiments.

  4. Temperature evaluation of dental implant surface irradiated with high-power diode laser. (United States)

    Rios, F G; Viana, E R; Ribeiro, G M; González, J C; Abelenda, A; Peruzzo, D C


    The prevalence of peri-implantitis and the absence of a standard approach for decontamination of the dental implant surface have led to searches for effective therapies. Since the source of diode lasers is portable, has reduced cost, and does not cause damage to the titanium surface of the implant, high-power diode lasers have been used for this purpose. The effect of laser irradiation on the implants is the elevation of the temperature surface. If this elevation exceeds 47 °C, the bone tissue is irreversibly damaged, so for a safety therapy, the laser parameters should be controlled. In this study, a diode laser of GaAsAl was used to irradiate titanium dental implants, for powers 1.32 to 2.64 W (real) or 2.00 to 4.00 W (nominal), in continuous/pulsed mode DC/AC, with exposure time of 5/10 s, with/without air flow for cooling. The elevation of the temperature was monitored in real time in two positions: cervical and apical. The best results for decontamination using a 968-nm diode laser were obtained for a power of 1.65 and 1.98 W (real) for 10 s, in DC or AC mode, with an air flow of 2.5 l/min. In our perspective in this article, we determine a suggested approach for decontamination of the dental implant surface using a 968-nm diode laser.

  5. REVIEW: Unconventional principles for designing high-power lasers with nonlinear frequency converters (United States)

    Smirnov, V. G.


    Studies of Raman lasers based on liquid nitrogen, gaseous hydrogen (stimulated Raman scattering by rotational and vibrational levels), and gaseous methane are reviewed. The studies selected for this review are of lasers excited by pulsed light from pumping sources with energies of 1 to 250 J, and which are designed in such a way that the results of the research can be scaled up. It has been shown that under certain conditions Raman lasers not only increase the brightness of laser light substantially but also become new sources of highpower coherent light in unexploited regions of the spectrum. Furthermore, in those cases in which the characteristics of the pump source—a neodymium laser—are close to their limiting values, and there is no need to raise the brightness, the use of a Raman laser as a final stage can increase the efficiency of the overall laser system by a factor of several units. This improvement opens up new possibilities for creating high-power laser systems with output energies greater than 1 kJ for physics research.

  6. Method and apparatus for delivering high power laser energy over long distances (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F


    Systems, devices and methods for the transmission and delivery of high power laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser drilling of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to advance such boreholes deep into the earth and at highly efficient advancement rates.

  7. Experimental astrophysics with high power lasers and Z pinches

    Energy Technology Data Exchange (ETDEWEB)

    Remington, B A; Drake, R P; Ryutov, D D


    With the advent of high energy density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch, pulsed-power facilities, mm-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. This has enabled the emergence of a new class of experimental science, HED laboratory astrophysics, wherein the properties of matter and the processes that occur under extreme astrophysical conditions can be examined in the laboratory. Areas particularly suitable to this class of experimental astrophysics include the study of opacities relevant to stellar interiors; equations of state relevant to planetary interiors; strong shock driven nonlinear hydrodynamics and radiative dynamics, relevant to supernova explosions and subsequent evolution; protostellar jets and high Mach-number flows; radiatively driven molecular clouds and nonlinear photoevaporation front dynamics; and photoionized plasmas relevant to accretion disks around compact objects, such as black holes and neutron stars.

  8. High-Power Solid-State Lasers from a Laser Glass Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J H; Hayden, J S; Marker, A J


    Advances in laser glass compositions and manufacturing have enabled a new class of high-energy/high-power (HEHP), petawatt (PW) and high-average-power (HAP) laser systems that are being used for fusion energy ignition demonstration, fundamental physics research and materials processing, respectively. The requirements for these three laser systems are different necessitating different glasses or groups of glasses. The manufacturing technology is now mature for melting, annealing, fabricating and finishing of laser glasses for all three applications. The laser glass properties of major importance for HEHP, PW and HAP applications are briefly reviewed and the compositions and properties of the most widely used commercial laser glasses summarized. Proposed advances in these three laser systems will require new glasses and new melting methods which are briefly discussed. The challenges presented by these laser systems will likely dominate the field of laser glass development over the next several decades.

  9. High power lasers and their industrial applications; Proceedings of the Meeting, Innsbruck, Austria, Apr. 15-18, 1986 (United States)

    Schuoecker, Dieter


    Papers are presented on the discharge behavior of an RF excited high power CO2 laser at different excitation frequencies; high power CO2 lasers for materials processing; a semiconductive preionization technique; high power Nd lasers for industrial applications; high power light transmission in optical waveguides; beam delivery systems for high power lasers; and quality control for high power CO2 laser optics. Topics discussed include the monitoring of laser material processes; measuring the quality of high power laser beams; the physics of laser material processing; metal precision drilling with lasers; and the evolution of microstructure for laser clad Fe-Cr-Mn-C alloys. Consideration is given to robotic manipulation for laser processing; laser cutting; the use of the laser versus the electron beam in welding the surface treatments; high power laser safety; and laser protective filters for the visible and near-IR spectrum.

  10. Effect of thermal management on the properties of saturable absorber mirrors in high-power mode-locked semiconductor disk lasers

    Energy Technology Data Exchange (ETDEWEB)

    Rantamaeki, Antti; Lyytikaeinen, Jari; Jari Nikkinen; Okhotnikov, Oleg G [Optoelectronics Research Center, Tampere University of Technology (Finland)


    The thermal management of saturable absorbers is shown to have a critical impact on a high-power mode-locked disk laser. The absorber with efficient heat removal makes it possible to generate ultrashort pulses with high repetition rates and high power density.

  11. Nanofabrication with Pulsed Lasers

    Directory of Open Access Journals (Sweden)

    Kabashin AV


    Full Text Available Abstract An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3, is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

  12. Interference effects at a dielectric plate applied as a high-power-laser attenuator. (United States)

    Gregorcic, Peter; Babnik, Ales; Mozina, Janez


    The interference effects caused by the Fresnel reflections of a Gaussian beam on the boundaries of a dielectric plate, which can be considered as a Fabry-Perot etalon, were theoretically and experimentally investigated. In addition to the incident angle and the polarization of the incident light, two additional parameters--the plate's parallelism and the temperature--which are often neglected, were analyzed. Based on the theoretical predictions and the measured behavior of the transmittance of the dielectric plate a new, temperature-controlled variable high-power-laser attenuator is proposed. Unwanted changes in the plate's transmittance caused by the absorption of laser pulses within the plate are also presented. These phenomena are important in many applications where dielectric plates are used for a variety of purposes.

  13. Beyond blue pico laser: development of high power blue and low power direct green (United States)

    Vierheilig, Clemens; Eichler, Christoph; Tautz, Sönke; Lell, Alfred; Müller, Jens; Kopp, Fabian; Stojetz, Bernhard; Hager, Thomas; Brüderl, Georg; Avramescu, Adrian; Lermer, Teresa; Ristic, Jelena; Strauss, Uwe


    There is a big need on R&D concerning visible lasers for projection applications. The pico-size mobile projection on the one hand awaits the direct green lasers with sufficiently long lifetimes at optical powers above 50mW. In this paper we demonstrate R&D-samples emitting at 519nm with lifetimes up to 10.000 hours. The business projection on the other hand requires high power operation and already uses blue lasers and phosphor conversion, but there is a strong demand for higher power levels. We investigate the power limits of R&D laser structures. In continuous wave operation, the power is limited by thermal roll-over. With an excellent power conversion efficiency of up to 29% the thermal roll-over is as high as 2.5W for a single emitter in TO56 can. We do not observe significant leakage at high currents. Driven in short pulse operation to prevent the laser from self heating, linear laser characteristics of optical power versus electrical current are observed up to almost 8W of optical power.

  14. High-power, high-fracture-strength, eye-safe Er:glass laser (United States)

    Tilleman, Michael M.; Jackel, Steven M.; Moshe, Innon


    We develop a high-power Er:strengthened-glass laser emitting at the eye-safe 1.535 micrometers wavelength. To maximize the output parameters of an Er:glass laser, whose power supply must also be used with Nd:YAG, a two-lamp laser head with parallel power forming networks that could be fired with an internal delay is used. The system operates at a slope efficiency of 0.45%, yielding a maximum pulse energy of 330 mJ. Thermal effects are measured, indicating strong thermal lensing, of 16 diopter/kW and mild birefringence induced depolarization of 5% at 200 W electrical power. From this data we determine the radial-tangential average and birefringence elasto-optical coefficients, Cr,(phi ) equals 0.075 +/- 0.002 and CB equals 0.0094, respectively. A TEM00 beam is achieved for a hemispherical resonator configuration. Based on the measurements, a design is presented for improved high-power TEM00 performance using principles based on dynamic compensation of thermal focusing and birefringence correction using a reentrant resonator.

  15. Energy coupling and plume dynamics during high power laser heating of metals

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, S. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Environmental Energy Technologies Div.


    High power laser heating of metals was studied utilizing experimental and numerical methods with an emphasis on the laser energy coupling with a target and on the dynamics of the laser generated vapor flow. Rigorous theoretical modeling of the heating, melting, and evaporation of metals due to laser radiation with a power density below the plasma shielding threshold was carried out. Experimentally, the probe beam deflection technique was utilized to measure the propagation of a laser induced shock wave. The effects of a cylindrical cavity in a metal surface on the laser energy coupling with a solid were investigated utilizing photothermal deflection measurements. A numerical calculation of target temperature and photothermal deflection was performed to compare with the measured results. Reflection of the heating laser beam inside the cavity was found to increase the photothermal deflection amplitude significantly and to enhance the overall energy coupling between a heating laser beam and a solid. Next, unsteady vaporization of metals due to nanosecond pulsed laser heating with an ambient gas at finite pressure was analyzed with a one dimensional thermal evaporation model for target heating and one dimensional compressible flow equations for inviscid fluid for the vapor flow. Lastly, the propagation of a shock wave during excimer laser heating of aluminum was measured with the probe beam deflection technique. The transit time of the shock wave was measured at the elevation of the probe beam above the target surface; these results were compared with the predicted behavior using ideal blast wave theory. The propagation of a gaseous material plume was also observed from the deflection of the probe beam at later times.

  16. High-Power, High-Efficiency 1.907nm Diode Lasers Project (United States)

    National Aeronautics and Space Administration — nLight developed high-power, high-efficiency laser diodes emitting at 1907nm for the pumping of solid-state lasers during the Phase I. The innovation brought to bear...

  17. High-power compact laser with segmented longitudinal pumping of coupled laser channels

    Energy Technology Data Exchange (ETDEWEB)

    Mamonov, D N; Il' ichev, N N; Sirotkin, A A; Pivovarov, P A; Derzhavin, S I; Klimentov, S M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Rebrov, S G [State Scientific Centre of Russian Federation — Federal State Unitary Enterprise Research Centre named after M V Keldysh (SSC FSUE Keldysh Research Centre) (Russian Federation)


    The characteristics of a compact Nd:YAG/Cr:YAG laser with segmented end pumping using a bundle of seven optical fibres are presented. In the regime of optical coupling of thus formed seven laser channels, 3-ns pulses with an energy up to 20 mJ, as well as their trains, are obtained. The used method makes it possible to scale the energy and power of lasers of this type with controlled spatial beam profile. (lasers)

  18. Cost-effective optoacoustic system based on the combination of high-power diode lasers (United States)

    Sánchez, Miguel; Rodríguez, Sergio; Gawali, Sandeep B.; Leggio, Luca; Gallego, Daniel C.; Lamela, Horacio


    One of the main issues of the advances in optoacoustic (OA) applications is to reduce the high costs and the big sizes of solid state lasers. High-power diode lasers (HPDLs) have been demonstrated to be a valid alternative reducing enormously the expenses, besides other advantages such as smaller sizes and higher modulation frequencies. However, in some cases it is possible to furtherly reduce their costs. We present a cost-effective OA system based on the combination of several 905-nm HPDLs with direct coupling into a fiber bundle. These HPDLs have an internal pulse driver, based on an n-channel Mosfet and two charging capacitors, which needs an external Mosfet driver circuit and a voltage supply in order to improve the optical pulse shape and energy. We compare the performances and the prices of this OA system with another similar HPDL-based OA system built with commercial elements. Results indicate good OA signal generation ( 15.6 mVpp) with pulse energy of 12.3 μJ and, especially, a cost reduction by a factor of 15 if compared to the other HPDL-based system.

  19. An Evaluation of the Cutting Potential of Different Types of High Power Lasers

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove


    based upon the historical development, the available cutting mechanisms understanding and the critical parameters involved in high power laser cutting. From the theoretical point of view, the new laser sources, the Disc-laser and the Fibre laser possess a potential of changing dramatically the limits......Laser cutting is a widespread industrial process. The boundaries for the performance of the lasers in terms of cutting capabilities is steadily moving towards higher cutting rates and thicker section cutting. In this paper the potential of different high power laser sources in cutting is evaluated...

  20. High power and high repetition solid state laser for EUV lithography

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, H.; Mitra, A.; Wang, T. and the others [Osaka Univ., Osaka (Japan)


    We have been developing a high repetition (5 kHz) and high power (5kW) Nd:YAG laser system for EUV lithography. Key subjects are (1) reliable front-end, (2) uniform and high density pumping of main amplifier rods, and (3) compensation of thermal effects. A stable and reliable front-end based on fiber lasers has been developed. As a cw oscillator using Yb-doped silica fiber operates single longitudinal mode at 1030 nm to 1080nm, various laser materials (Yb:YAG, Nd:YLF, Nd:YAG, Nd:YAP, etc) can be used as main laser medium. A fast LN EO modulator switches out arbitrary pulse shape with response time of 100 ps. Laser pulses from the modulator are amplified by 3 stage fiber amplifiers up to 1 J. We will focus our efforts to attain 1 mJ output from the fiber front-end. Output pulses from the front-end are amplified to 100 mJ level by two 4-mm rod amplifiers (Nd:YAG) and two 6-mm rod amplifiers. Main amplifier chain consists of eight 12-mm rod amplifiers pumped by cw laser diodes. Total output power of the laser diodes is 28.8 kW. Double pass geometry is required to get enough gain and to compensate thermal effects. Spatial filters are installed to adjust thermal lens in the amplifiers and to send an image into just the center of the amplifiers. Ninty degree rotators and faraday rotators are installed in order to compensate thermal birefringence. A test amplifier module was made for investigation on uniform pumping, thermal effects, gain properties, and so on. Six laser diode modules with 4.5 kW total output power are installed in symmetric configuration. Active medium is Nd:YAG rod with 0.6% doping. Diameter and length of the rod are 12 mm and 150 mm, respectively. Peak gain of 1.67 was obtained at 4.2 kW pumping power and 200s pumping duration. Pumping uniformity was measured by both gain distribution and spontaneous emission from the laser rod. Fairly good uniformity was achieved by adjusting pumping geometry. Detail system analysis suggests that 8 amplifier modules

  1. Use of high-power lasers in oral surgery (United States)

    Gaspar, Lajos


    The treatment of 2989 patients with different type of lasers was described. The argon laser beam was used in 57 cases (portwine stains, telangiectasias, angiofibromas and other vascular lesions) and 84 operations were performed by Nd:YAG laser (leukoplakia, hemangioma etc.) furthermore 53 operations by combined laser beam. 2795 operations by carbon dioxide laser were performed in precancerous states and other white lesions, benign tumors and tumor-like states, malignant tumors and other lesions.

  2. CrN/AlN nanolaminate coatings deposited via high power pulsed and middle frequency pulsed magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bagcivan, N.; Bobzin, K. [Surface Engineering Institute, RWTH Aachen University, Kackertstr. 15, D-52072 Aachen (Germany); Ludwig, A.; Grochla, D. [Institute for Materials, Ruhr-Universität Bochum, Universitätsstraße 150, D-44801 Bochum (Germany); Brugnara, R.H., E-mail: [Surface Engineering Institute, RWTH Aachen University, Kackertstr. 15, D-52072 Aachen (Germany)


    Nanolaminate coatings based on transition metal nitrides such as CrN, AlN and TiN deposited via physical vapor deposition (PVD) have shown great advantage as protective coatings on tools and components subject to high loads in tribological applications. By varying the individual layer materials and their thicknesses it is possible to optimize the coating properties, e.g. hardness, Young's modulus and thermal stability. One way for further improvement of coating properties is the use of advanced PVD technologies. High power pulsed magnetron sputtering (HPPMS) is an advancement of pulsed magnetron sputtering (MS). The use of HPPMS allows a better control of the energetic bombardment of the substrate due to the higher ionization degree of metallic species. It provides an opportunity to influence chemical and mechanical properties by varying the process parameters. The present work deals with the development of CrN/AlN nanolaminate coatings in an industrial scale unit by using two different PVD technologies. Therefore, HPPMS and mfMS (middle frequency magnetron sputtering) technologies were used. The bilayer period Λ, i.e. the thickness of a CrN/AlN double layer, was varied between 6.2 nm and 47.8 nm by varying the rotational speed of the substrate holders. In a second step the highest rotational speed was chosen and further HPPMS CrN/AlN coatings were deposited applying different HPPMS pulse lengths (40, 80, 200 μs) at the same mean cathode power and frequency. Thickness, morphology, roughness and phase composition of the coatings were analyzed by means of scanning electron microscopy (SEM), confocal laser microscopy, and X-ray diffraction (XRD), respectively. The chemical composition was determined using glow discharge optical emission spectroscopy (GDOES). Detailed characterization of the nanolaminate was conducted by transmission electron microscopy (TEM). The hardness and the Young's modulus were analyzed by nanoindentation measurements. The residual

  3. [Development of a High Power Green Laser Therapeutic Equipment for Hyperplasia of Prostate]. (United States)

    Liang, Jie; Kang, Hongxiang; Shen, Benjian; Zhao, Lusheng; Wu, Xinshe; Chen, Peng; Chang, Aihong; Guo Hua; Guo, Jiayu


    The basic theory of high power green laser equipment for prostate hyperplasia therapy and the components of the system developed are introduced. Considering the requirements of the clinical therapy, the working process of the high power green laser apparatus are designed and the laser with stable output at 120 W is achieved. The controlling hardware and application software are developed, and the safety step is designed. The high power green laser apparatus manufactured with characteristics of stable output, multifunctional and friendly interface provides a choices of prostate hyperplasia therapy for using nationalization instrument.

  4. High power laser-mechanical drilling bit and methods of use (United States)

    Grubb, Daryl L.; Kolachalam, Sharath K.; Faircloth, Brian O.; Rinzler, Charles C.; Allen, Erik C.; Underwood, Lance D.; Zediker, Mark S.


    An apparatus with a high power laser-mechanical bit for use with a laser drilling system and a method for advancing a borehole. The laser-mechanical bit has a beam path and mechanical removal devices that provide for the removal of laser-affected rock to advance a borehole.

  5. High-power multimode X-band rf pulse compression system for future linear colliders

    Directory of Open Access Journals (Sweden)

    Sami G. Tantawi


    Full Text Available We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC. The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  6. All-optical Q-switching limiter for high-power gigahertz modelocked diode-pumped solid-state lasers. (United States)

    Klenner, Alexander; Keller, Ursula


    Passively modelocked diode-pumped solid-state lasers (DPSSLs) with pulse repetition rates in the gigahertz regime suffer from an increased tendency for Q-switching instabilities. Low saturation fluence intracavity saturable absorbers - such as the semiconductor saturable absorber mirrors (SESAMs) - can solve this problem up to a certain average output power limited by the onset of SESAM damage. Here we present a passive stabilization mechanism, an all-optical Q-switching limiter, to reduce the impact of Q-switching instabilities and increase the potential output power of SESAM modelocked lasers in the gigahertz regime. With a proper cavity design a Kerr lens induced negative saturable absorber clamps the maximum fluence on the SESAM and therefore limits the onset of Q-switching instabilities. No critical cavity alignment is required because this Q-switching limiter acts well within the cavity stability regime. Using a proper cavity design, a high-power diode-pumped Yb:CALGO solid-state laser generated sub-100 fs pulses with an average output power of 4.1 W at a pulse repetition rate of 5 GHz. With a pulse duration of 96 fs we can achieve a peak power as high as 7.5 kW directly from the SESAM modelocked laser oscillator without any further external pulse amplification and/or pulse compression. We present a quantitative analysis of this Kerr lens induced Q-switching limiter and its impact on modelocked operation. Our work provides a route to compact high-power multi-gigahertz frequency combs based on SESAM modelocked diode-pumped solid-state lasers without any additional external amplification or pulse compression.

  7. Method and system for advancement of a borehole using a high power laser (United States)

    Moxley, Joel F.; Land, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Zediker, Mark S.


    There is provided a system, apparatus and methods for the laser drilling of a borehole in the earth. There is further provided with in the systems a means for delivering high power laser energy down a deep borehole, while maintaining the high power to advance such boreholes deep into the earth and at highly efficient advancement rates, a laser bottom hole assembly, and fluid directing techniques and assemblies for removing the displaced material from the borehole.

  8. Methods for enhancing the efficiency of creating a borehole using high power laser systems (United States)

    Zediker, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Koblick, Yeshaya; Moxley, Joel F.


    Methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena to enhance the formation of Boreholes. Methods for the laser operations to reduce the critical path for forming a borehole in the earth. These methods can deliver high power laser energy down a deep borehole, while maintaining the high power to perform operations in such boreholes deep within the earth.

  9. Functionally graded materials produced with high power lasers

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Pei, Y.T.; Kumar, A; Chung, YW; Moore, JJ; Doll, GL; Yatsui, K; Misra, DS


    With a well-controlled laser melt injection (LMI) process, for the first time the feasibility is demonstrated to produce SiC particles (SiCp) reinforced Ti6Al4V functionally graded materials (FGMs). SiCp are injected just behind the laser beam into the extended part of the laser melt pool that is

  10. High-power LED light sources for optical measurement systems operated in continuous and overdriven pulsed modes (United States)

    Stasicki, Bolesław; Schröder, Andreas; Boden, Fritz; Ludwikowski, Krzysztof


    The rapid progress of light emitting diode (LED) technology has recently resulted in the availability of high power devices with unprecedented light emission intensities comparable to those of visible laser light sources. On this basis two versatile devices have been developed, constructed and tested. The first one is a high-power, single-LED illuminator equipped with exchangeable projection lenses providing a homogenous light spot of defined diameter. The second device is a multi-LED illuminator array consisting of a number of high-power LEDs, each integrated with a separate collimating lens. These devices can emit R, G, CG, B, UV or white light and can be operated in pulsed or continuous wave (CW) mode. Using an external trigger signal they can be easily synchronized with cameras or other devices. The mode of operation and all parameters can be controlled by software. Various experiments have shown that these devices have become a versatile and competitive alternative to laser and xenon lamp based light sources. The principle, design, achieved performances and application examples are given in this paper.

  11. High-power graphene mode-locked Tm/Ho co-doped fiber laser with evanescent field interaction. (United States)

    Li, Xiaohui; Yu, Xuechao; Sun, Zhipei; Yan, Zhiyu; Sun, Biao; Cheng, Yuanbing; Yu, Xia; Zhang, Ying; Wang, Qi Jie


    Mid-infrared ultrafast fiber lasers are valuable for various applications, including chemical and biomedical sensing, material processing and military applications. Here, we report all-fiber high-power graphene mode-locked Tm/Ho co-doped fiber laser at long wavelength with evanescent field interaction. Ultrafast pulses up to 7.8 MHz are generated at a center wavelength of 1879.4 nm, with a pulse width of 4.7 ps. A graphene absorber integrated with a side-polished fiber can increase the damage threshold significantly. Harmonics mode-locking can be obtained till to the 21(th) harmonics at a pump power of above 500 mW. By using one stage amplifier in the anomalous dispersion regime, the laser can be amplified up to 450 mW and the narrowest pulse duration of 1.4 ps can be obtained simultaneously. Our work paves the way to graphene Tm/Ho co-doped mode-locked all-fiber master oscillator power amplifiers as potentially efficient and economic laser sources for high-power laser applications, such as special material processing and nonlinear optical studies.

  12. Applications of high power lasers in the battlefield (United States)

    Kalisky, Yehoshua


    Laser weapon is currently considered as tactical as well as strategic beam weapons, and is considered as a part of a general layered defense system against ballistic missiles and short-range rockets. This kind of weapon can disable or destroy military targets or incoming objects used by small groups of terrorists or countries, at the speed of light. Laser weapon is effective at long or short distances, owing to beam's unique characteristics such as narrow bandwidth, high brightness, coherent both in time and space, and it travels at the speed of light. Unlike kinetic weapon, laser weapon converts the energy stored in an electromagnetic laser beam into a large amount of heat aimed on a small area spot at the skin of the missile, usually close to the liquid fuel storage tank, warhead case or engine area, following by a temperature increase and finally-catastrophic failure by material ablation or melt. The usefulness of laser light as a weapon has been studied for decades but only in recent years became feasible. There are two types of lasers being used: gas lasers and solid state lasers, including fiber lasers. All these types of lasers will be discussed below.

  13. DUV high power lasers processing for glass and CFRP (United States)

    Kobayashi, Masakazu; Kakizaki, Kouji; Oizumi, Hiroaki; Mimura, Toshio; Fujimoto, Junichi; Mizoguchi, Hakaru


    A laser processing is widely applied to cutting, drilling, welding, bending and surface treatment in industry. Lasers with a wavelength of 1 μm are mainly used and the processing is realized by melting materials. This thermal process has a high productivity but the processed surface is hard to use for precision machining. This report is focusing on two materials which are classified in wide band gap. Ablation rate was measured with a laser microscope and an optical one. Excimer laser is expected to be a useful tool for these materials

  14. High power fiber laser system for a high repetition rate laserwire

    Directory of Open Access Journals (Sweden)

    L. J. Nevay


    Full Text Available We present the development of a high power fiber laser system to investigate its suitability for use in a transverse electron beam profile monitor, i.e., a laserwire. A system capable of producing individual pulses up to 165.8±0.4  μJ at 1036 nm with a full width at half maximum of 1.92±0.12  ps at 6.49 MHz is demonstrated using a master oscillator power amplifier design with a final amplification stage in a rod-type photonic crystal fiber. The pulses are produced in trains of 1 ms in a novel burst mode amplification scheme to match the bunch pattern of the charged particles in an accelerator. This method allows pulse energies up to an order of magnitude greater than the steady-state value of 17.0±0.6  μJ to be achieved at the beginning of the burst with a demonstrated peak power of 25.8±1.7  MW after compression. The system is also shown to demonstrate excellent spatial quality with an M^{2}=1.26±0.01 in both dimensions, which would allow nearly diffraction limited focusing to be achieved.

  15. Development of a high-power blue laser (445  nm) for material processing. (United States)

    Wang, Hongze; Kawahito, Yosuke; Yoshida, Ryohei; Nakashima, Yuya; Shiokawa, Kunio


    A blue diode laser has a higher absorption rate than a traditional laser, while the maximum power is limited. We report the structure and laser beam profile of a 250 W high-power blue laser (445 nm) for material processing. The absorption rate of the blue laser system for the steel was 2.75 times that of a single-mode fiber laser system (1070 nm). The characteristics of the steel after laser irradiation were determined, validating the potential of this high-power blue laser for material processing, such as heat treatment and cladding. The cost of the developed laser system was lower than that of the existing one. To the best of our knowledge, this is the first blue laser with a power as high as 250 W.

  16. Influence of a falling edge on high power microwave pulse combination (United States)

    Li, Jiawei; Huang, Wenhua; Zhu, Qi; Xiao, Renzhen; Shao, Hao


    This paper presents an explanation of the influence of a microwave falling edge on high-power microwave pulse combination. Through particle-in-cell simulations, we discover that the falling edge is the driving factor that limits the output power of the combined pulses. We demonstrate that the space charge field, which accumulates to become comparable to the E-field at the falling edge of the former pulse, will trap the electrons in the gas layer and decrease its energy to attain a high ionization rate. Hence, avalanche discharge, caused by trapped electrons, makes the plasma density to approach the critical density and cuts off the latter microwave pulse. An X-band combination experiment is conducted with different pulse intervals. This experiment confirms that the high density plasma induced by the falling edge can cut off the latter pulse, and that the time required for plasma recombination in the transmission channel is several microseconds. To ensure a high output power for combined pulses, the latter pulse should be moved ahead of the falling edge of the former one, and consequently, a beat wave with high peak power becomes the output by adding two pulses with normal amplitudes.

  17. High power visible diode laser for the treatment of eye diseases by laser coagulation (United States)

    Heinrich, Arne; Hagen, Clemens; Harlander, Maximilian; Nussbaumer, Bernhard


    We present a high power visible diode laser enabling a low-cost treatment of eye diseases by laser coagulation, including the two leading causes of blindness worldwide (diabetic retinopathy, age-related macular degeneration) as well as retinopathy of prematurely born children, intraocular tumors and retinal detachment. Laser coagulation requires the exposure of the eye to visible laser light and relies on the high absorption of the retina. The need for treatment is constantly increasing, due to the demographic trend, the increasing average life expectancy and medical care demand in developing countries. The World Health Organization reacts to this demand with global programs like the VISION 2020 "The right to sight" and the following Universal Eye Health within their Global Action Plan (2014-2019). One major point is to motivate companies and research institutes to make eye treatment cheaper and easily accessible. Therefore it becomes capital providing the ophthalmology market with cost competitive, simple and reliable technologies. Our laser is based on the direct second harmonic generation of the light emitted from a tapered laser diode and has already shown reliable optical performance. All components are produced in wafer scale processes and the resulting strong economy of scale results in a price competitive laser. In a broader perspective the technology behind our laser has a huge potential in non-medical applications like welding, cutting, marking and finally laser-illuminated projection.

  18. High Power Optically Pumped Semiconductor Lasers for Sodium Guidestar Applications (United States)

    Hackett, Shawn


    Optically pumped semiconductor lasers (OPSLs) are shown to provide a much more compact and less expensive source for illumination of the sodium layer of the mesosphere for use as a sodium laser guidestar via single and two photon excitation schemes. This represents a revolution in laser guidestar technology as the cost, size, and power requirements for a laser guidestar system are shown to have been decreased by an order of magnitude with guidestar performance shown to be similar to previous sources. Sodium laser guidestar sources for broadband simultaneous illumination of multiple lines are developed and simulated. Simulations are then compared to actual returns for multi-line sodium laser guidestars. The simultaneous multi-line laser guidestar is shown to be superior to the single line laser guidestar for equal output powers both via modeling and via on sky returns performed at Starfire Optical Range (SOR) with a combination of a legacy narrowband laser guidestars and a broadband OPSL guidestar. The multi-line OPSL guidestars are shown to provide the first continuous wave source for use as a polychromatic laser guidestar (PLGS) to correct for tip and tilt aberrations. Different methods for utilization of the PLGS are simulated and compared showing that the OPSL sources developed are suitable for use as a CW PLGS to correct for tip and tilt with current generation telescopes and adaptive optics systems. Wave optics and Bloch equation simulations are then developed and performed to determine the utility and optimal setup for LGS and PLGS systems which prove OPSL's utility as the next generation of sodium laser guidestars.

  19. Faraday isolator based on TSAG crystal for high power lasers. (United States)

    Mironov, E A; Palashov, O V


    A Faraday isolator based on a new magneto-optical medium, TSAG (terbium scandium aluminum garnet) crystal, has been constructed and investigated experimentally. The device provides an isolation ratio of more than 30 dB at 500 W laser power. It is shown that this medium can be used in Faraday isolators for kilowatt-level laser powers.

  20. Solar Pumped High Power Solid State Laser for Space Applications (United States)

    Fork, Richard L.; Laycock, Rustin L.; Green, Jason J. A.; Walker, Wesley W.; Cole, Spencer T.; Frederick, Kevin B.; Phillips, Dane J.


    Highly coherent laser light provides a nearly optimal means of transmitting power in space. The simplest most direct means of converting sunlight to coherent laser light is a solar pumped laser oscillator. A key need for broadly useful space solar power is a robust solid state laser oscillator capable of operating efficiently in near Earth space at output powers in the multi hundred kilowatt range. The principal challenges in realizing such solar pumped laser oscillators are: (1) the need to remove heat from the solid state laser material without introducing unacceptable thermal shock, thermal lensing, or thermal stress induced birefringence to a degree that improves on current removal rates by several orders of magnitude and (2) to introduce sunlight at an effective concentration (kW/sq cm of laser cross sectional area) that is several orders of magnitude higher than currently available while tolerating a pointing error of the spacecraft of several degrees. We discuss strategies for addressing these challenges. The need to remove the high densities of heat, e.g., 30 kW/cu cm, while keeping the thermal shock, thermal lensing and thermal stress induced birefringence loss sufficiently low is addressed in terms of a novel use of diamond integrated with the laser material, such as Ti:sapphire in a manner such that the waste heat is removed from the laser medium in an axial direction and in the diamond in a radial direction. We discuss means for concentrating sunlight to an effective areal density of the order of 30 kW/sq cm. The method integrates conventional imaging optics, non-imaging optics and nonlinear optics. In effect we use a method that combines some of the methods of optical pumping solid state materials and optical fiber, but also address laser media having areas sufficiently large, e.g., 1 cm diameter to handle the multi-hundred kilowatt level powers needed for space solar power.

  1. High-power diode-pumped Tm:YLF slab laser

    CSIR Research Space (South Africa)

    Schellhorn, M


    Full Text Available The aim is to develop a high-power Tm:YLF slab laser which can be utilized to pump a Ho slab laser. A 68 W Tm:YLF slab laser was recently presented in [1] pumped from one end by a single 6-bar stack delivering ~300 W of pump power. In this work, we...

  2. Recent Results in High Power CO2-Laser Cutting for Shipbuilding Industry

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Juhl, Thomas Winther; Nielsen, Jakob Skov


    In 1997 a high power laser cutting and welding test facility was established at the Danish shipyard Odense Steel Shipyard (OSS). Research and development projects were initiated in order to establish the basis for applying the full power of the laser for laser-cutting, by developing mirror based...... cutting systems. In this paper the results of these projects will be presented....

  3. Permeabilization of yeast Saccharomyces cerevisiae cell walls using nanosecond high power electrical pulses (United States)

    Stirke, A.; Zimkus, A.; Balevicius, S.; Stankevic, V.; Ramanaviciene, A.; Ramanavicius, A.; Zurauskiene, N.


    The electrical field-induced changes of the yeast Saccharomyces cerevisiae cells permeabilization to tetraphenylphosphonium (TPP+) ions were studied using square-shaped, nanosecond duration high power electrical pulses. It was obtained that pulses having durations ranging from 10 ns to 60 ns, and generating electric field strengths up to 190 kV/cm significantly (up to 65 times) increase the absorption rate of TPP+ ions without any detectible influence on the yeast cell viability. The modelling of the TPP+ absorption process using a second order rate equation demonstrates that depending on the duration of the pulses, yeast cell clusters of different sizes are homogeniously permeabilized. It was concluded, that nanosecond pulse-induced permeabilization can be applied to increase the operational speed of whole cell biosensors.

  4. Ferroelectric switch for a high-power Ka-band active pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)


    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  5. Efficient High Power 2 micron Tm3+-Doped Fiber Laser Project (United States)

    National Aeronautics and Space Administration — This proposal is for the development of new Tm3+ doped germanate glass fibers for efficient high power 2-micron fiber lasers capable of generating an output power of...

  6. Efficient high power 2 micron Tm3+-Doped Fiber Laser Project (United States)

    National Aeronautics and Space Administration — This proposal is for the development of new Tm3+ doped germanate glass fibers for efficient high power 2 micron fiber lasers capable of generating an output power of...

  7. High-Power, High-Efficiency 1.907nm Diode Lasers Project (United States)

    National Aeronautics and Space Administration — nLight proposes to develop high-power, high-efficiency laser diodes emitting at 1907nm. Performance is expected to improve from the current state-of-the-art...

  8. High-power gain-switched Tm(3+)-doped fiber laser. (United States)

    Tang, Yulong; Xu, Lin; Yang, Yi; Xu, Jianqiu


    Gain-switched by a 1.914-µm Tm:YLF crystal laser, a two-stage Tm(3+) fiber laser has been achieved 100-W level ~2-µm pulsed laser output with a slope efficiency of ~52%. With the 6-m length of Tm fiber, the laser wavelength was centered at 2020 nm with a bandwidth of ~25 nm. Based on an acousto-optic switch, the pulse repetition rate can be modulated from 500 Hz to 50 kHz, and the laser pulse width can be tuned between 75 ns and ~1 µs. The maximum pulse energy was over 10 mJ, and the maximum pulse peak power was 138 kW. By using the fiber-coiling-induced mode-filtering effect, laser beam quality of M2 = 1.01 was obtained. Further scaling the pulse energy and average power from such kind of gain-switched fiber lasers was also discussed.

  9. Laser assisted die bending: a new application of high power diode lasers (United States)

    Schuöcker, D.; Schumi, T.; Spitzer, O.; Bammer, F.; Schuöcker, G.; Sperrer, G.


    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.

  10. Optical fiber cable for transmission of high power laser energy over great distances (United States)

    Zediker, Mark S.; Rinzler, Charles C.; Faircloth, Brian O.; Moxley, Joel F.; Koblick, Yeshaya


    There is provided a system and apparatus for the transmission of high power laser energy over great distances without substantial power loss and without the presence of stimulated Raman scattering. There is further provided systems and optical fiber cable configurations and optical fiber structures for the delivering high power laser energy over great distances to a tool or surface to perform an operation or work with the tool or upon the surface.

  11. Optical Properties of Lithium Terbium Fluoride and Implications for Performance in High Power Lasers (Postprint) (United States)



  12. Pulsed laser ablation of copper (United States)

    Jordan, R.; Cole, D.; Lunney, J. G.; Mackay, K.; Givord, D.


    The laser ablation of copper with a 532 nm, 6 ns laser has been investigated in the regime normally used for pulsed laser deposition. The ablation depth per pulse and the flux and energy distribution of the ions in the plume were measured and compared to the deposition rate as measured by a quartz microbalance. These measurements were compared with an analytic model of ablation via a laser sustained plasma. It is shown that self-sputtering of the growing film is significant.

  13. Tunable high-power narrow-linewidth green external-cavity GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael


    A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system.......A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system....

  14. A compact high power Er:Yb:glass eyesafe laser for infrared remote sensing applications (United States)

    Vitiello, Marco; Pizzarulli, Andrea; Ruffini, Andrea


    The key features and performances of a compact, lightweight, high power Er3+:Yb3+ glass laser transmitter are reported on. The theory employed to get an optimal design of the device is also described. In free running regime high energies of about 15mJ in 3ms long pulses were obtained, with an optical efficiency close to 85%. When q-switched by a Co: MALO crystal of carefully selected initial transmittivity, a high peak power in excess of 500 kW was obtained in about 9ns pulse duration, with an optical efficiency of 60%. The laser was successfully run with no significant power losses at repetition rates up to 5Hz due to a carefully designed heat sink which allowed an efficient conduction cooling of both the diode bars and the phosphate glass. The transmitter emits at a wavelength of 1535nm in the so-called "eyesafe" region of the light spectrum thus being highly attractive for any application involving the risk of human injury as is typically the case in remote sensing activities. Moreover, the spectral band around 1,5mm corresponds to a peak in the athmospheric transmittance thus being more effective in adverse weather conditions with respect to other wavelengths. Actually, the device has been successfully integrated into a rangefinder system allowing a reliable and precise detection of small targets at distances up to 20Km. Moreover, the transmitter capabilities were used into a state of the art infrared laser illuminator for night vision allowing even the recognition of a human being at distances in excess of 5Km.

  15. High-power rod-type photonic crystal fiber laser (United States)

    Limpert, J.; Deguil-Robin, N.; Manek-Hönninger, I.; Salin, F.; Röser, F.; Liem, A.; Schreiber, T.; Nolte, S.; Zellmer, H.; Tünnermann, A.; Broeng, J.; Petersson, A.; Jakobsen, C.


    We report on a novel ytterbium-doped fiber design that combines the advantages of rod and fiber gain media. The fiber design has outer dimensions of a rod laser, meaning a diameter in the range of a few millimeters and a length of just a few tens of centimeters, and includes two important waveguide structures, one for pump radiation and one for laser radiation. We obtained 120-W output power in single-mode beam quality from a 48-cm-long fiber cane that corresponds to an extracted power of 250 W/m. The fiber has significantly reduced nonlinearity, which therefore allows for scalability in the performance of a high-peak-power fiber laser and amplifier system.

  16. High Power Diode Lasers with External Feedback: Overview and Prospects

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael


    In summary, different external-cavity feedback techniques to improve the spatial beam quality and narrow the linewidth of the output beam from both BALs and TDLs are presented. Broad-area diode laser system with external-cavity feedback around 800 nm can produce several Watts of output power...... with a good beam quality. Tapered diode laser systems with external-cavity feedback around 800 and 1060 nm can deliver more than 2 W output power with diffraction-limited beam quality and can be operated in single-longitudinal mode. These high-brightness, narrow linewidth, and tunable external-cavity diode...

  17. High-power, military ruggedized QCL-based laser systems (United States)

    Takeuchi, Eric B.; Chapman, William B.; Arnone, David; Pushkarsky, Michael; Lopez, Enrique; Young, Michael; Caffey, Dave; Borgardt, Brandon; Priest, Allen; Sensibaugh, Jason; Day, Timothy


    Daylight Solutions has pioneered the development and commercialization of quantum cascade laser (QCL) technology for commercial and military markets. Multi-Watt, multi-wavelength QCL-based systems have been manufactured and tested against harsh military environmental requirements for military applications. These self-contained, turn-key systems have been designed to comply with modular open system architecture (MOSA) principles, and have been proven in several different system geometries. This paper will highlight the environmental requirements imposed upon, and performance from, QCL-based laser systems for example military applications.

  18. High power 938 nanometer fiber laser and amplifier (United States)

    Dawson, Jay W [Livermore, CA; Liao, Zhi Ming [Pleasanton, CA; Beach, Raymond J [Livermore, CA; Drobshoff, Alexander D [Livermore, CA; Payne, Stephen A [Castro Valley, CA; Pennington, Deanna M [Livermore, CA; Hackenberg, Wolfgang [Munich, DE; Calia, Domenico Bonaccini [Garching, DE; Taylor, Luke [Montauban de Bretagne, FR


    An optical fiber amplifier includes a length of silica optical fiber having a core doped with neodymium, a first cladding and a second cladding each with succeeding lower refractive indices, where the first cladding diameter is less than 10 times the diameter of the core. The doping concentration of the neodymium is chosen so that the small signal absorption for 816 nm light traveling within the core is less than 15 dB/m above the other fiber losses. The amplifier is optically pumped with one laser into the fiber core and with another laser into the first cladding.

  19. Design of measurement equipment for high power laser beam shapes

    DEFF Research Database (Denmark)

    Hansen, K. S.; Olsen, F. O.; Kristiansen, Morten


    -chip implemented in a camera system. Most available CCD-based systems do however suffer from a low maximum intensity threshold. Therefore attenuation is needed. This paper describes the construction of such a beam analysing system where beam patterns produced by single mode fiber laser on a diffractic optical...

  20. High power laser having a trivalent liquid host (United States)

    Ault, Earl R.


    A laser having a lasing chamber and a semiconductor pumping device with trivalent titanium ions dissolved in a liquid host within the lasing chamber. Since the host is a liquid, it can be removed from the optical cavity when it becomes heated avoiding the inevitable optical distortion and birefringence common to glass and crystal hosts.

  1. Ignition studies in support of the European High Power Laser ...

    Indian Academy of Sciences (India)

    Fast ignition; inertial fusion energy; thermonuclear ignition; radiation hy- drodynamics simulation. PACS Nos 28.52.Av; 47.70.Mc; 52.57.Kk; 52.57.-z; 89.30.Jj. 1. Introduction. Inertial confinement fusion ..... [11] P Verlade, F Ogando, S Eliezer, J M Martinez-Val, J M Perlado and M Murakami,. Lasers and Particle Beams 23, 1, ...

  2. Technology of discharge and laser resonators for high power CO2 lasers. Koshutsuryoku CO2 laser ni tsukawareru hoden reiki laser kyoshinki gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Y.; Kuzumoto, M. (Mitsubishi Electric Corp., Tokyo (Japan))


    This paper describes discharge excitation technology and resonator technology as basic technologies for high power CO2 lasers. As a result of progress in high-frequency power element techniques, the discharge excitation technology now generally uses laser excitation using AC discharge of capacity coupling type. Its representative example is silent discharge (SD) excitation. This is a system to excite laser by applying high voltages with as high frequency as 100 kHz to 1 MHz across a pair of electrodes covered with a dielectric material. The system maintains stability in discharge even if power supply voltage amplitude is modulated, and easily provides pulse outputs. Discharge excitation for diffusion cooled type CO2 laser generates a discharge in a gap with a gap length of about 2 mm, and can perform gas cooling by means of thermal conduction of gas, whereas a compact resonator can be fabricated. A resonator for the diffusion cooled type CO2 laser eliminates gas circulation and cooling systems, hence the device can be made more compact. A report has been given that several of these compact resonators were combined, from which a laser output of 85W was obtained by using RF discharge of 2kW. 43 refs., 21 figs.

  3. Transmission line pulse system for avalanche characterization of high power semiconductor devices (United States)

    Riccio, Michele; Ascione, Giovanni; De Falco, Giuseppe; Maresca, Luca; De Laurentis, Martina; Irace, Andrea; Breglio, Giovanni


    Because of the increasing in power density of electronic devices for medium and high power application, reliabilty of these devices is of great interest. Understanding the avalanche behaviour of a power device has become very important in these last years because it gives an indication of the maximum energy ratings which can be seen as an index of the device ruggedness. A good description of this behaviour is given by the static IV blocking characteristc. In order to avoid self heating, very relevant in high power devices, very short pulses of current have to be used, whose value can change from few milliamps up to tens of amps. The most used method to generate short pulses is the TLP (Transmission Line Pulse) test, which is based on charging the equivalent capacitance of a transmission line to high value of voltage and subsequently discharging it onto a load. This circuit let to obtain very short square pulses but it is mostly used for evaluate the ESD capability of semiconductor and, in this environment, it generates pulses of low amplitude which are not high enough to characterize the avalanche behaviour of high power devices . Advanced TLP circuit able to generate high current are usually very expensive and often suffer of distorption of the output pulse. In this article is proposed a simple, low cost circuit, based on a boosted-TLP configuration, which is capable to produce very square pulses of about one hundreds of nanosecond with amplitude up to some tens of amps. A prototype is implemented which can produce pulses up to 20A of amplitude with 200 ns of duration which can characterize power devices up to 1600V of breakdown voltage. Usage of microcontroller based logic make the circuit very flexible. Results of SPICE simulation are provided, together with experimental results. To prove the effectiveness of the circuit, the I-V blocking characteristics of two commercial devices, namely a 600V PowerMOS and a 1200V Trench-IGBT, are measured at different

  4. Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers

    DEFF Research Database (Denmark)

    Shirakawa, A.; Chen, M.; Suzuki, Y.


    Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot. Multicore fiber lasers are a promising tool for power scaling by coherent beam combination. © 2014 OSA....

  5. Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers

    DEFF Research Database (Denmark)

    Shirakawa, A.; Chen, M.; Suzuki, Y.


    Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot. Multicore fiber lasers are a promising tool for power scaling by coherent beam combination. © 2014 OSA.......Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot. Multicore fiber lasers are a promising tool for power scaling by coherent beam combination. © 2014 OSA....

  6. Design and characterization of a novel power over fiber system integrating a high power diode laser (United States)

    Perales, Mico; Yang, Mei-huan; Wu, Cheng-liang; Hsu, Chin-wei; Chao, Wei-sheng; Chen, Kun-hsein; Zahuranec, Terry


    High power 9xx nm diode lasers along with MH GoPower's (MHGP's) flexible line of Photovoltaic Power Converters (PPCs) are spurring high power applications for power over fiber (PoF), including applications for powering remote sensors and sensors monitoring high voltage equipment, powering high voltage IGBT gate drivers, converters used in RF over Fiber (RFoF) systems, and system power applications, including powering UAVs. In PoF, laser power is transmitted over fiber, and is converted to electricity by photovoltaic cells (packaged into Photovoltaic Power Converters, or PPCs) which efficiently convert the laser light. In this research, we design a high power multi-channel PoF system, incorporating a high power 976 nm diode laser, a cabling system with fiber break detection, and a multichannel PPC-module. We then characterizes system features such as its response time to system commands, the PPC module's electrical output stability, the PPC-module's thermal response, the fiber break detection system response, and the diode laser optical output stability. The high power PoF system and this research will serve as a scalable model for those interested in researching, developing, or deploying a high power, voltage isolated, and optically driven power source for high reliability utility, communications, defense, and scientific applications.

  7. Department of Defense High Power Laser Program Guidance (United States)


    Energy Weapon, HELSTF, TMD PIi ,,(A I,, ’!t "• •k ’ .I• r•i oAe"If)t p I ;’ ~ j’ ti• ’ cr •’A ssrIr.(A fl N 1 ’) S (’I)tI!I1 Y ( I A • J k’TV•"’, j ’i...the Chemical Oxygen Iodine Laser (COIL) operating at 1.3 pm. The Free Electron Laser (FEL), soiid state and other advanced concepts bring additional...Reprographics K X-Ray Lithography B Optical Fiber Comm G Tissue Cutting L Heat Treatment C Remote Sensing H Photodynamic Therapy M Cutting/Welding D

  8. High-power dual-rod Yb:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Honea, Eric C.; Beach, Raymond J.; Mitchell, Scott C.; Skidmore, Jay A.; Emanuel, Mark A.; Sutton, Steven B.; Payne, Stephen A.; Avizonis, Petras V.; Monroe, Robert S.; Harris, Dennis G.


    We describe a diode-pumped Yb:YAG laser that produces 1080 W of power cw with 27.5% optical optical efficiency and 532 W Q -switched with M{sup 2}=2.2 and 17% optical-optical efficiency. The laser uses two composite Yb:YAG rods separated by a 90 degree sign quartz rotator for bifocusing compensation. A microlensed diode array end pumps each rod, using a hollow lens duct for pump delivery. By changing resonator parameters we can adjust the fundamental mode size and the output beam quality. Using a flattened Gaussian intensity profile to calculate the mode-fill efficiency and clipping losses, we compare experimental data with modeled output power versus beam quality. (c) 2000 Optical Society of America.

  9. Advanced high-power pulsed light device to decontaminate food from pathogens: effects on Salmonella typhimurium viability in vitro. (United States)

    Luksiene, Z; Gudelis, V; Buchovec, I; Raudeliuniene, J


    The aim of this study was to construct an advanced high-power pulsed light device for decontamination of food matrix and to evaluate its antibacterial efficiency. Key parameters of constructed device-emitted light spectrum, pulse duration, pulse power density, frequency of pulses, dependence of emitted spectrum on input voltage, irradiation homogenicity, possible thermal effects as well as antimicrobial efficiency were evaluated. Antimicrobial efficiency of high-power pulsed light technique was demonstrated and evaluated by two independent methods - spread plate and Miles-Misra method. Viability of Salmonella typhimurium as function of a given light dose (number of pulses) and pulse frequency was examined. According to the data obtained, viability of Salmonella typhimurium reduced by 7 log order after 100 light pulses with power density 133 W cm(-2). In addition, data indicate, that the pulse frequency did not influence the outcome of pathogen inactivation in the region 1-5 Hz. Moreover, no hyperthermic effect was detected during irradiation even after 500 pulses on all shelves with different distance from light source and subsequently different pulse power density (0-252 W cm(-2)). Newly constructed high-power pulsed light technique is effective nonthermal tool for inactivation of Salmonella typhimurium even by 7 log order in vitro. Novel advanced high-power pulsed light device can be a useful tool for development of nonthermal food decontamination technologies.

  10. Laser system using ultra-short laser pulses (United States)

    Dantus, Marcos [Okemos, MI; Lozovoy, Vadim V [Okemos, MI; Comstock, Matthew [Milford, MI


    A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

  11. Water Vapour Propulsion Powered by a High-Power Laser-Diode (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  12. High-power random distributed feedback fiber laser: From science to application

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xueyuan [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Naval Academy of Armament, Beijing 100161 (China); Zhang, Hanwei; Xiao, Hu; Ma, Pengfei; Wang, Xiaolin; Zhou, Pu; Liu, Zejin [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)


    A fiber laser based on random distributed feedback has attracted increasing attention in recent years, as it has become an important photonic device and has found wide applications in fiber communications or sensing. In this article, recent advances in high-power random distributed feedback fiber laser are reviewed, including the theoretical analyses, experimental approaches, discussion on the practical applications and outlook. It is found that a random distributed feedback fiber laser can not only act as an information photonics device, but also has the feasibility for high-efficiency/high-power generation, which makes it competitive with conventional high-power laser sources. In addition, high-power random distributed feedback fiber laser has been successfully applied for midinfrared lasing, frequency doubling to the visible and high-quality imaging. It is believed that the high-power random distributed feedback fiber laser could become a promising light source with simple and economic configurations. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Cladding glass ceramic for use in high powered lasers (United States)

    Marker, Alexander J.; Campbell, John H.


    A Cu-doped/Fe-doped low expansion glass ceramic composition comprising in Wt. %: SiO{sub 2} 50--65; Al{sub 2}O{sub 3} 18--27; P{sub 2}O{sub 5} 0--10; Li{sub 2}O 2--6; Na{sub 2}O 0--2; K{sub 2}O 0--2; B{sub 2}O{sub 3} 0--1; MgO 0--4; ZnO 0--5; CaO 0--4; BaO 0--5; TiO{sub 2} 1--3; ZrO{sub 3} 1--3; As{sub 2}O{sub 3} 0--1.5; Sb{sub 2}O{sub 3} 0--1.5; CuO 0--3; and Fe{sub 2}O{sub 3} 0--1 wherein the total amount of SiO{sub 2}, Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} is 80--89 wt. %, and said glass ceramic contains as a dopant 0.1--3 wt. % CuO, 0.1--1 wt. % Fe{sub 2}O{sub 3} or a combined CuO+Fe{sub 2}O{sub 3} amount of 0.1--4 wt. %. The glass ceramic composition is suitable for use as a cladding material for solid laser energy storage mediums as well as for use in beam attenuators for measuring laser energy level and beam blocks or beam dumps used for absorbing excess or unused laser energy.

  14. High-power non linear frequency converted laser diodes

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Hansen, Anders Kragh


    We present different methods of generating light in the blue-green spectral range by nonlinear frequency conversion of tapered diode lasers achieving state-of-the-art power levels. In the blue spectral range, we show results using single-pass second harmonic generation (SHG) as well as cavity...... enhanced sum frequency generation (SFG) with watt-level output powers. SHG and SFG are also demonstrated in the green spectral range as a viable method to generate up to 4 W output power with high efficiency using different configurations....

  15. Widely Tunable High-Power Tapered Diode Laser at 1060 nm

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Sumpf, Bernd; Erbert, Götz


    We report a large tuning range from 1018 to 1093 nm from a InGaAs single quantum-well 1060-nm external cavity tapered diode laser. More than 2.5-W output power has been achieved. The tuning range is to our knowledge the widest obtained from a high-power InGaAs single quantum-well tapered laser...

  16. High power singlemode GaInAs lasers with distributed Bragg reflectors (United States)

    O'Brien, S.; Parke, R.; Welch, D. F.; Mehuys, D.; Scifres, D.


    High power singlemode strained GaInAs lasers have been fabricated which use buried second order gratings as distributed Bragg reflectors. The lasers operate in an edge emitting fashion with CW powers in excess of 110 mW with single longitudinal and transverse mode operation at 971.9 nm up to 42 mW.

  17. Rugged passively cooled high power laser fiber optic connectors and methods of use (United States)

    Rinzler, Charles C.; Gray, William C.; Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.; McKay, Ryan P.


    There are provided high power laser connectors and couplers and methods that are capable of providing high laser power without the need for active cooling to remote, harsh and difficult to access locations and under difficult and harsh conditions and to manage and mitigate the adverse effects of back reflections.

  18. Energy balance in high-power CO2 laser welding (United States)

    Del Bello, Umberto; Rivela, Cristina; Cantello, Maichi; Penasa, Mauro


    The laser energy impinging on a metal workpiece is partially absorbed and partially reflected by the material surface. This work is aimed at gaining a better insight into the energy balance of the process, and it can also provide the correct input for process modeling and the optimum choice of parameters for increasing welding efficiency. Measurements of the absorption coefficient were made using platinum-platinum rhodium thermocouples which monitored the temperature rise. The radiation backscattered by the workpiece or plasma plume was also recorded, and tests were performed to measure the total amount of material lost by evaporation during laser welding. All the tests were performed on austenitic stainless steel. The resulting absorption curves show different behavior at low or high speed and this can be explained only by taking into account the influence on the process of both the size and inclination of the keyhole. To conserve the keyhole, the interaction process must be rapidly interrupted so as to freeze the molten material and preserve the cavity in the form assumed during the process. A fast mechanical switch has been devised and tests seem to confirm the assumption made.

  19. Advances in High-Power, Ultrashort Pulse DPSSL Technologies at HiLASE

    Directory of Open Access Journals (Sweden)

    Martin Smrž


    Full Text Available The development of kW-class diode-pumped picosecond laser sources emitting at various wavelengths started at the HiLASE Center four years ago. A 500-W Perla C thin-disk laser with a diffraction limited beam and repetition rate of 50–100 kHz, a frequency conversion to mid-infrared (mid-IR, and second to fifth harmonic frequencies was demonstrated. We present an updated review on the progress in the development of compact picosecond and femtosecond high average power radiation sources covering the ultraviolet (UV to mid-IR spectral range at the HiLASE Center. We also report on thin-disk manufacturing by atomic diffusion bonding, which is a crucial technology for future high-power laser development.

  20. Progress in high-power continuous-wave quantum cascade lasers [Invited]. (United States)

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


    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.

  1. Optical pulses, lasers, measuring techniques

    CERN Document Server

    Früngel, Frank B A


    High Speed Pulse Technology: Volume II: Optical Pulses - Lasers - Measuring Techniques focuses on the theoretical and engineering problems that result from the capacitor discharge technique.This book is organized into three main topics: light flash production from a capacitive energy storage; signal transmission and ranging systems by capacitor discharges and lasers; and impulse measuring technique. This text specifically discusses the air spark under atmospheric conditions, industrial equipment for laser flashing, and claims for light transmitting system. The application of light impulse sign

  2. Review of high-power pulsed systems at the Institute of High Current Electronics

    Directory of Open Access Journals (Sweden)

    A.A. Kim


    Full Text Available In this paper, we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics (HCEI, Siberian Branch, Russian Academy of Sciences, and describe latest achievements of the teams dealing with these installations. Besides the presented high-power systems, HCEI performs numerous investigations using much less powerful generators. For instance, last year much attention was paying to the research and development of the intense low-energy (<200 kV high-current electron and ion beam and plasma sources, and their application in the technology [1–3].

  3. 1-MHz high power femtosecond Yb-doped fiber chirped-pulse amplifier (United States)

    Hu, Zhong-Qi; Yang, Pei-Long; Teng, Hao; Zhu, Jiang-Feng; Wei, Zhi-Yi


    A practical femtosecond polarization-maintaining Yb-doped fiber amplifier enabling 153 fs transform-limited pulse duration with 32 μJ pulse energy at 1 MHz repetition rate corresponding to a peak power of 0.21 GW is demonstrated. The laser system based on chirped-pulse amplification (CPA) technique is seeded by a dispersion managed, nonlinear polarization evolution (NPE) mode-locked oscillator with spectrum bandwidth of 31 nm at 1040 nm and amplified by three fiber pre-amplifying stages and a rod type fiber main amplifying stage. The laser works with beam quality of M2 of 1.3 and power stability of 0.63% (root mean square, RMS) over 24 hours will be stable sources for industrial micromachining, medical therapy and scientific research.

  4. Cryogenic, high power, near diffraction limited, Yb:YAG slab laser. (United States)

    Ganija, Miftar; Ottaway, David; Veitch, Peter; Munch, Jesper


    A cryogenic slab laser that is suitable for scaling to high power, while taking full advantage of the improved thermo-optical and thermo-mechanical properties of Yb:YAG at cryogenic temperatures is described. The laser uses a conduction cooled, end pumped, zigzag slab geometry resulting in a near diffraction limited, robust, power scalable design. The design and the initial characterization of the laser up to 200W are presented.

  5. Development of a high power free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Min; Lee, Byung Chul; Kim, Sun Kook; Jung, Yung Wook; Cho, Sung Oh [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    A millimeter-wave free electron laser (FEL) driven by a recirculating electrostatic accelerator has been developed. The wavelength of the FEL is tunable in the range of 3 - 12 mm by tuning the energy of the electron beam. The output power is estimated to be 1 kW. The electrostatic accelerator is composed of high-current electron gun, acceleration tube, high-voltage generator, high-voltage terminal, deceleration tube, electron collator, and vacuum pumps. Two types of LaB{sub 6}-based thermionic electron guns (triode gun and diode gun) and their power supplies have been developed. The voltage of the guns is 30 kV and the output current is - 2 A. A beam-focusing planar undulator and a permanent-magnet helical undulator have been developed and 3D trajectories of electron beam in the undulators have been calculated to find optimal input condition of electron beam. 135 figs, 15 pix, 17 tabs, 98 refs. (Author).

  6. All fiber-based Yb-doped high energy, high power femtosecond fiber lasers. (United States)

    Wan, Peng; Yang, Lih-Mei; Liu, Jian


    Two all fiber-based laser systems are demonstrated to achieve high energy and high average power femtosecond pulsed outputs at wavelength of 1 µm. In the high energy laser system, a pulse energy of 1.05 mJ (0.85 mJ after pulse compressor) at 100 kHz repetition rate has been realized by a Yb-doped ultra large-core single-mode photonic crystal fiber (PCF) rod amplifier, seeded with a 50 µJ fiber laser. The pulse duration is 705 fs. In the high average power experiment, a large mode area (LMA) fiber has been used in the final stage amplifier, seeded with a 50 W mode locked fiber laser. The system is running at a repetition rate of 69 MHz producing 1052 W of average power before compressor. After pulse compression, a pulse duration of 800 fs was measured.

  7. High-power diode laser versus electrocautery surgery on human papillomavirus lesion treatment. (United States)

    Baeder, Fernando Martins; Santos, Maria Teresa Botti R; Pelino, Jose Eduardo Pelizon; Duarte, Danilo Antonio; Genovese, Walter Joao


    The use of high-power lasers has facilitated and improved human papillomavirus (HPV) treatment protocols and has also become very popular in recent years. This application has been more frequently used in hospitals, especially in gynecology. The present study aimed to evaluate the effects of high-power diode laser to remove oral lesions caused by HPV and the consequent effects on virus load following the wound tissue healing process compared with one of the most conventional surgical techniques involving electrocautery. Surgeries were performed on 5 patients who had 2 distinct lesions caused by HPV. All patients were submitted to both electrocautery and high-power diode laser. Following a 20-day period, when the area was healed, sample material was collected through curettage for virus load quantitative analysis.Observation verified the presence of virus in all the samples; however, surgeries performed with the laser also revealed a significant reduction in virus load per cell compared with those performed with electrocautery. The ease when handling the diode laser, because of the flexibility of its fibers and precision of its energy delivery system, provides high-accuracy surgery, which facilitates the treatment of large and/or multifocal lesions. The use of high-power diode laser is more effective in treatment protocols of lesions caused by HPV.

  8. Reliability of high power/brightness diode lasers emitting from 790 to 980 nm (United States)

    Bao, L.; Bai, J.; Price, K.; Devito, M.; Grimshaw, M.; Dong, W.; Guan, X.; Zhang, S.; Zhou, H.; Bruce, K.; Dawson, D.; Kanskar, M.; Martinsen, R.; Haden, J.


    This paper presents recent progress in the development of high power single emitter laser diodes from 790 nm to 980 nm for reliable use in industrial and pumping applications. High performance has been demonstrated on diode lasers from 790 nm to 980 nm, with corresponding peak efficiency ~65%. Reliability has been fully demonstrated on high power diode lasers of 3.8 mm laser cavity at 3 major wavelengths. We report on the correlation between photon-energy (wavelength) and device failure modes (reliability). A newly released laser design demonstrates diode lasers with 5.0 mm laser cavity at 915-980 nm and 790 nm, with efficiency that matches the values achieved with 3.8 mm cavity length. 915-980 nm single emitters with 5.0 mm laser cavity were especially designed for high power and high brightness applications and can be reliably operated at 12 W to 18 W. These pumps have been incorporated into nLIGHT's newly developed fiber coupled pump module, elementTM. Ongoing highly accelerated diode life-tests have accumulated over 200,000 raw device hours, with extremely low failure rate observed to date. High reliability has also been demonstrated from multiple accelerated module-level lifetests.

  9. High Power Laser Laboratory at the Institute of Plasma Physics and Laser Microfusion: equipment and preliminary research

    Directory of Open Access Journals (Sweden)

    Zaraś-Szydłowska Agnieszka


    Full Text Available The purpose of this paper is to present the newly-opened High Power Laser Laboratory (HPLL at the Institute of Plasma Physics and Laser Microfusion (IPPLM. This article describes the laser, the main laboratory accessories and the diagnostic instruments. We also present preliminary results of the first experiment on ion and X-ray generation from laser-produced plasma that has been already performed at the HPLL.

  10. Short-pulse laser interactions with disordered materials and liquids

    Energy Technology Data Exchange (ETDEWEB)

    Phinney, L.M.; Goldman, C.H.; Longtin, J.P.; Tien, C.L. [Univ. of California, Berkeley, CA (United States)


    High-power, short-pulse lasers in the picosecond and subpicosecond range are utilized in an increasing number of technologies, including materials processing and diagnostics, micro-electronics and devices, and medicine. In these applications, the short-pulse radiation interacts with a wide range of media encompassing disordered materials and liquids. Examples of disordered materials include porous media, polymers, organic tissues, and amorphous forms of silicon, silicon nitride, and silicon dioxide. In order to accurately model, efficiently control, and optimize short-pulse, laser-material interactions, a thorough understanding of the energy transport mechanisms is necessary. Thus, fractals and percolation theory are used to analyze the anomalous diffusion regime in random media. In liquids, the thermal aspects of saturable and multiphoton absorption are examined. Finally, a novel application of short-pulse laser radiation to reduce surface adhesion forces in microstructures through short-pulse laser-induced water desorption is presented.

  11. Train of high-power femtosecond pulses: Probe wave in a gas of prepared atoms (United States)

    Muradyan, Gevorg; Muradyan, Atom Zh.


    We present a method for generating a regular train of ultrashort optical pulses in a prepared two-level medium. The train develops from incident monochromatic probe radiation traveling in a medium of atoms, which are in a quantum mechanical superposition of dressed internal states. In the frame of linear theory for the probe radiation, the energy of individual pulses is an exponentially growing function of atom density and of interaction cross section. Pulse repetition rate is determined by the pump field’s generalized Rabi frequency and can be around 1 THz and greater. We also show that the terms, extra to the dipole approximation, endow the gas by a new property: nonsaturating dependence of refractive index on dressing monochromatic field intensity. Contribution of these nonsaturating terms can be compatible with the main dipole approximation term contribution in the wavelength region of about ten micrometers (the range of CO2 laser) or larger.

  12. High-power AlGaAs channeled substrate planar diode lasers for spaceborne communications (United States)

    Connolly, J. C.; Goldstein, B.; Pultz, G. N.; Slavin, S. E.; Carlin, D. B.; Ettenberg, M.


    A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described.

  13. Thermal tuning of volume Bragg gratings for spectral beam combining of high-power fiber lasers. (United States)

    Drachenberg, Derrek R; Andrusyak, Oleksiy; Venus, George; Smirnov, Vadim; Glebov, Leonid B


    High-radiance lasers are desired for many applications in defense and manufacturing. Spectral beam combining (SBC) by volume Bragg gratings (VBGs) is a very promising method for high-radiance lasers that need to achieve 100 kW level power. Laser-induced heating of VBGs under high-power radiation presents a challenge for maintaining Bragg resonance at various power levels without mechanical realignment. A novel thermal tuning technique and apparatus is presented that enables maintaining peak efficiency operation of the SBC system at various power levels without any mechanical adjustment. The method is demonstrated by combining two high-power ytterbium fiber lasers with high efficiency from low power to full combined power of 300 W (1.5 kW effective power), while maintaining peak combining efficiency within 0.5%.

  14. Atmospheric propagation of high power laser radiation at different weather conditions


    Pargmann, Carsten; Hall, Thomas; Duschek, Frank; Handke, Jürgen


    Applications based on the propagation of high power laser radiation through the atmosphere are limited in range and effect, due to weather dependent beam wandering, beam deterioration, and scattering processes. Security and defense related application examples are countermeasures against hostile projectiles and the powering of satellites and aircrafts. For an examination of the correlations between weather condition and laser beam characteristics DLR operates at Lampoldshausen a 130 m long fr...

  15. Angled grating high-power semiconductor lasers: simulation of beam characteristics under thermal effects (United States)

    Sarangan, Andrew M.


    The angled grating laser has been successful in achieving high-power diffraction-limited beams. The laser cavity utilizes a grating inclined at an angle to the facet to filter out the filamented beams. As a result, all of the filamented beams except the primary beam will be transmitted through the grating. In this paper we present the cavity resonance equation, and study temperature sensitivity of this device.

  16. Does hypericin boost the efficacy of high-power laser? A preliminary experimental study on rats. (United States)

    Zor, Murat; Goktas, Serdar; Yildirim, Ibrahim; Zorba, Unal Orhan; Basal, Seref; Alp, Bilal Firat; Kaya, Engin; Erogul, Osman


    Lasers are widely used in treating symptomatic benign prostatic hyperplasia. In current practice, potassium titanyl phosphate (KTP) lasers are the most common type of laser systems used. The aim here was to evaluate the rapid effect of high-power laser systems after application of hypericin. Experimental animal study conducted in the Department of Urology, Gülhane Military Medical Academy, Ankara, Turkey, in 2012. Sixteen rats were randomized into four groups: 120 W KTP laser + hypericin; 120 W KTP laser alone; 80 W KTP laser + hypericin; and 80 W KTP laser alone. Hypericin was given intraperitoneally two hours prior to laser applications. The laser incisions were made through the quadriceps muscle of the rats. The depth and the width of the laser incisions were evaluated histologically and recorded. To standardize the effects of the laser, we used the ratio of depth to width. These new values showed us the depth of the laser application per unit width. The new values acquired were evaluated statistically. Mean depth/width values were 231.6, 173.6, 214.1 and 178.9 in groups 1, 2, 3 and 4, respectively. The most notable result was that higher degrees of tissue penetration were achieved in the groups with hypericin (P laser applications.

  17. Realization and characterization of single-frequency tunable 637.2 nm high-power laser

    CERN Document Server

    Wang, Jieying; He, Jun; Wang, Junmin


    We report the generation of narrow-linewidth 637.2 nm laser by single-pass sum-frequency generation (SFG) of two infrared lasers at 1560.5 nm and 1076.9 nm in PPMgO:LN crystal. Over 8.75 W of single-frequency continuously tunable 637.2 nm laser is realized, and corresponding conversion efficiency is 38%. We study the behavior of crystals with different poling periods. The detailed experiments show that the output red lasers have very good power stability and beam quality. This high-performance 637.2 nm laser is significant for the realization of high power ultra-violet (UV) 318.6 nm laser via cavity-enhanced frequency doubling. Narrow-linewidth 318.6 nm laser is important for Rydberg excitation of cesium atoms via single-photon transition.

  18. Injection locking of a low cost high power laser diode at 461 nm. (United States)

    Pagett, C J H; Moriya, P H; Celistrino Teixeira, R; Shiozaki, R F; Hemmerling, M; Courteille, Ph W


    Stable laser sources at 461 nm are important for optical cooling of strontium atoms. In most existing experiments, this wavelength is obtained by frequency doubling infrared lasers, since blue laser diodes either have low power or large emission bandwidths. Here, we show that injecting less than 10 mW of monomode laser radiation into a blue multimode 500 mW high power laser diode is capable of slaving at least 50% of the power to the desired frequency. We verify the emission bandwidth reduction by saturation spectroscopy on a strontium gas cell and by direct beating of the slave with the master laser. We also demonstrate that the laser can efficiently be used within the Zeeman slower for optical cooling of a strontium atomic beam.

  19. Semiconductor laser engineering, reliability and diagnostics a practical approach to high power and single mode devices

    CERN Document Server

    Epperlein, Peter W


    This reference book provides a fully integrated novel approach to the development of high-power, single-transverse mode, edge-emitting diode lasers by addressing the complementary topics of device engineering, reliability engineering and device diagnostics in the same book, and thus closes the gap in the current book literature. Diode laser fundamentals are discussed, followed by an elaborate discussion of problem-oriented design guidelines and techniques, and by a systematic treatment of the origins of laser degradation and a thorough exploration of the engineering means to enhance the optical strength of the laser. Stability criteria of critical laser characteristics and key laser robustness factors are discussed along with clear design considerations in the context of reliability engineering approaches and models, and typical programs for reliability tests and laser product qualifications. Novel, advanced diagnostic methods are reviewed to discuss, for the first time in detail in book literature, performa...

  20. Remote detection of radioactive material using high-power pulsed electromagnetic radiation. (United States)

    Kim, Dongsung; Yu, Dongho; Sawant, Ashwini; Choe, Mun Seok; Lee, Ingeun; Kim, Sung Gug; Choi, EunMi


    Remote detection of radioactive materials is impossible when the measurement location is far from the radioactive source such that the leakage of high-energy photons or electrons from the source cannot be measured. Current technologies are less effective in this respect because they only allow the detection at distances to which the high-energy photons or electrons can reach the detector. Here we demonstrate an experimental method for remote detection of radioactive materials by inducing plasma breakdown with the high-power pulsed electromagnetic waves. Measurements of the plasma formation time and its dispersion lead to enhanced detection sensitivity compared to the theoretically predicted one based only on the plasma on and off phenomena. We show that lower power of the incident electromagnetic wave is sufficient for plasma breakdown in atmospheric-pressure air and the elimination of the statistical distribution is possible in the presence of radioactive material.

  1. Remote detection of radioactive material using high-power pulsed electromagnetic radiation (United States)

    Kim, Dongsung; Yu, Dongho; Sawant, Ashwini; Choe, Mun Seok; Lee, Ingeun; Kim, Sung Gug; Choi, EunMi


    Remote detection of radioactive materials is impossible when the measurement location is far from the radioactive source such that the leakage of high-energy photons or electrons from the source cannot be measured. Current technologies are less effective in this respect because they only allow the detection at distances to which the high-energy photons or electrons can reach the detector. Here we demonstrate an experimental method for remote detection of radioactive materials by inducing plasma breakdown with the high-power pulsed electromagnetic waves. Measurements of the plasma formation time and its dispersion lead to enhanced detection sensitivity compared to the theoretically predicted one based only on the plasma on and off phenomena. We show that lower power of the incident electromagnetic wave is sufficient for plasma breakdown in atmospheric-pressure air and the elimination of the statistical distribution is possible in the presence of radioactive material. PMID:28486438

  2. Remote detection of radioactive material using high-power pulsed electromagnetic radiation (United States)

    Kim, Dongsung; Yu, Dongho; Sawant, Ashwini; Choe, Mun Seok; Lee, Ingeun; Kim, Sung Gug; Choi, Eunmi


    Remote detection of radioactive materials is impossible when the measurement location is far from the radioactive source such that the leakage of high-energy photons or electrons from the source cannot be measured. Current technologies are less effective in this respect because they only allow the detection at distances to which the high-energy photons or electrons can reach the detector. Here we demonstrate an experimental method for remote detection of radioactive materials by inducing plasma breakdown with the high-power pulsed electromagnetic waves. Measurements of the plasma formation time and its dispersion lead to enhanced detection sensitivity compared to the theoretically predicted one based only on the plasma on and off phenomena. We show that lower power of the incident electromagnetic wave is sufficient for plasma breakdown in atmospheric-pressure air and the elimination of the statistical distribution is possible in the presence of radioactive material.

  3. Development of modular scalable pulsed power systems for high power magnetized plasma experiments (United States)

    Bean, I. A.; Weber, T. E.; Adams, C. S.; Henderson, B. R.; Klim, A. J.


    New pulsed power switches and trigger drivers are being developed in order to explore higher energy regimes in the Magnetic Shock Experiment (MSX) at Los Alamos National Laboratory. To achieve the required plasma velocities, high-power (approx. 100 kV, 100s of kA), high charge transfer (approx. 1 C), low-jitter (few ns) gas switches are needed. A study has been conducted on the effects of various electrode geometries and materials, dielectric media, and triggering strategies; resulting in the design of a low-inductance annular field-distortion switch, optimized for use with dry air at 90 psig, and triggered by a low-jitter, rapid rise-time solid-state Linear Transformer Driver. The switch geometry and electrical characteristics are designed to be compatible with Syllac style capacitors, and are intended to be deployed in modular configurations. The scalable nature of this approach will enable the rapid design and implementation of a wide variety of high-power magnetized plasma experiments. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. Approved for unlimited release, LA-UR-17-2578.

  4. Single-clad Tm-Ho:fiber amplifier for high-power sub-100-fs pulses around 1.9 μm. (United States)

    Coluccelli, Nicola; Cassinerio, Marco; Laporta, Paolo; Galzerano, Gianluca


    A Tm-Ho:fiber amplifier based on single-clad geometry is demonstrated for the generation of high-power femtosecond pulses around 1.9 μm. The amplifier is seeded by the low-power Raman soliton generated by an Er:fiber femtosecond laser. Pulse trains at a repetition rate of 250 MHz tunable from 1.84 to 1.92 μm with corresponding powers from 2.6 to 3 W and durations from 80 to 105 fs have been obtained. Beating with a single-frequency Tm laser has shown that the pulse coherence is highly preserved. The overall power fluctuations have been measured to be as low as 0.6%.

  5. High power burst-mode optical parametric amplifier with arbitrary pulse selection. (United States)

    Pergament, M; Kellert, M; Kruse, K; Wang, J; Palmer, G; Wissmann, L; Wegner, U; Lederer, M J


    We present results from a unique burst-mode femtosecond non-collinear optical parametric amplifier (NOPA) under development for the optical - x-ray pump-probe experiments at the European X-Ray Free-Electron Laser Facility. The NOPA operates at a burst rate of 10 Hz, a duty cycle of 2.5% and an intra-burst repetition rate of up to 4.5 MHz, producing high fidelity 15 fs pulses at a center wavelength of 810 nm. Using dispersive amplification filtering of the super-continuum seed pulses allows for selectable pulse duration up to 75 fs, combined with a tuning range in excess of 100 nm whilst remaining nearly transform limited. At an intra-burst rate of 188 kHz the single pulse energy from two sequential NOPA stages reached 180 µJ, corresponding to an average power of 34W during the burst. Acousto- and electro-optic switching techniques enable the generation of transient free bursts of required length and the selection of arbitrary pulse sequences inside the burst.

  6. Microstructural evolution in additive manufacturing with high power lasers : Deposition, characterization and performance

    NARCIS (Netherlands)

    Nenadl, Ondrej


    High power lasers provide time and cost effective method for metallic surface modification. In this work these modifications are explored as: 1) a simple melting and subsequent rapid solidification of a metallic surface – resulting in superior properties post-treatment; 2) deposition of an

  7. Spectral, spatial and temporal control of high-power diode lasers through nonlinear optical feedback

    NARCIS (Netherlands)

    van Voorst, P.D.


    A high-power diode laser offers multi-Watt output power from a small and efficient device, which makes them an interesting source for numerous applications. The spatial and spectral output however, are of reduced quality which limits the applicability. This limited quality is connected to the design

  8. Degradation Processes in High-Power Diode Lasers under External Optical Feedback

    DEFF Research Database (Denmark)

    Tomm, Jens. W.; Hempel, Martin; Petersen, Paul Michael


    The effect of moderate external feedback on the gradual degradation of 808 nm emitting AlGaAs-based high-power broad-area diode lasers is analyzed. Eventually the quantum well that actually experiences the highest total optical load remains unaffected by the aging, while severe impact...

  9. Mini-percutaneous nephrolithotomy with high-power holmium YAG laser in pediatric patients with staghorn and complex calculi. (United States)

    Bujons, Anna; Millán, Félix; Centeno, Clara; Emiliani, Esteban; Sánchez Martín, Francisco; Angerri, Oriol; Caffaratti, Jorge; Villavicencio, Humberto


    Shock wave lithotripsy (SWL) is the treatment of choice for most cases of renal lithiasis in children. Some cases, however, are refractory to SWL and may be associated with anatomic and metabolic changes or a large stone burden. In these circumstances, mini-percutaneous nephrolithotomy (mini-PCNL) is an option. The aim was to assess the safety and efficacy of high-power holmium YAG (Ho:YAG) laser in mini-PCNL for staghorn calculi. The clinical records relating to 35 mini-PCNLs (Table) performed between January 2008 and December 2012 in 33 patients (27 boys and 6 girls; mean age 7 years, range 2-18 years) were retrospectively reviewed. Twenty-two (66.7%) of the patients had undergone a previous SWL (28.6% three sessions). The mini-PCNL puncture technique used involved fluoroscopic guidance with the C arm at 0-90° in the supine position. An 18F tract was used. Stone fragmentation was performed with a high-power Ho:YAG laser (Lumenis 100 W). Ten of the mini-PCNLs (28.6%) were right sided, and 25 were left sided (71.4%). Stones were located in the lower calyceal group in 64% of patients and in the renal pelvis in 50%. The mean stone size was 4.46 cm(2) (range 3-13.20 cm(2)). The number of stones varied between one and 20, and 83.3% were radiopaque. The laser was set at 70 W (range 50-100 W) (3.5 J/pulse with a frequency of 20 pulses/s). The mean surgical time was 150 min. In 78% of patients, complete stone clearance was achieved, and the overall stone-free rate rose to 85% when residual stones were treated with either SWL or retrograde intrarenal surgery. No perioperative complications were seen. There are few reports in the literature concerning the use of a high-power laser for treatment of complex stones and the few that do exist relate to adults have similar results, showing it to be highly effective and safe, with low morbidity. Some limitations of the present study must be acknowledged. It was retrospective and a relatively small number of patients were

  10. Pulsed Scophony laser projection system (United States)

    Lowry, J. B.; Welford, W. T.; Humphries, M. R.


    A novel laser TV projection display has been developed by PA Technology employing the Scophony system with acousto-optic modulators and pulsed lasers. This results in a projection system with greater optical simplicity, higher reliability and reduced power and cooling requirements over similar laser projectors. The technique has been successfully implemented in British Aerospace's Microdome missile training simulator. This paper describes the underlying principles of the design, its operational features and its implementation in the Microdome.

  11. High Power Mid-IR Laser Development 2.8 to 3.5 Microns Project (United States)

    National Aeronautics and Space Administration — Advance the state of the art in continuous wave and pulsed IR distributed feedback (DFB) and optical parametric generation (OPG) lasers between 2.8 and 3.5 μm to...

  12. Analysis of High-Power Diode Laser Heating Effects on HY-80 Steel for Laser Assisted Friction Stir Welding Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wiechec, Maxwell; Baker, Brad; McNelley, Terry; Matthews, Manyalibo; Rubenchik, Alexander; Rotter, Mark; Beach, Ray; Wu, Sheldon


    In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.

  13. Control and performance improvements of a pulse compressor in use for testing accelerating structures at high power

    Directory of Open Access Journals (Sweden)

    Benjamin Woolley


    Full Text Available New developments relating to compact X-band, SLED-I type pulse compressors being developed at CERN for testing high gradient structures are described. Pulse compressors of interest take rf pulses from one or more high power klystrons with duration typically >1.5  μs and deliver up to 5 times the input power for a shorter duration <250  ns. Time domain models for pulse compressor operation with low level rf (LLRF control have been developed. Input drive amplitude and phase for each pulse is evolved with a control algorithm from the pulse compressor output for previous pulses. The goal is to deliver precise amplitude for pulses to test stands and precise amplitude and phase for pulses to accelerator systems. Control algorithms have been developed and validated experimentally.

  14. Method and system for processing optical materials for high power laser systems (United States)

    Demos, Stavros G; Raman, Rajesh; Negres, Raluca A


    A method of determining conditioning pulse parameters for an optical element includes directing a pump pulse to impinge on the optical element and directing a probe pulse to impinge on the optical element. The method also includes determining a first time associated with an onset of electronic excitation leading to formation of an absorbing region of the optical element and determining a second time associated with expansion of the absorbing region of the optical element. The method further includes defining a turn-off time for a conditioning pulse between the first time and the second time. According to embodiments of the present invention, pulse shaping of the conditioning pulse enables laser conditioning of optical elements to achieve improvements in their laser induced damage threshold.

  15. Design of a high-power, high-brightness Nd:YAG solar laser. (United States)

    Liang, Dawei; Almeida, Joana; Garcia, Dário


    A simple high-power, high-brightness Nd:YAG solar laser pumping approach is presented in this paper. The incoming solar radiation is both collected and concentrated by four Fresnel lenses and redirected toward a Nd:YAG laser head by four plane-folding mirrors. A fused-silica secondary concentrator is used to compress the highly concentrated solar radiation to a laser rod. Optimum pumping conditions and laser resonator parameters are found through ZEMAX and LASCAD numerical analysis. Solar laser power of 96 W is numerically calculated, corresponding to the collection efficiency of 24  W/m². A record-high solar laser beam brightness figure of merit of 9.6 W is numerically achieved.

  16. Nontraditional principles of designing high-power lasers with nonlinear converters (United States)

    Smirnov, V. G.


    A review is presented of Raman lasers based on liquid nitrogen, methane gas, and hydrogen gas as active media. It is shown that, under certain conditions, Raman lasers not only can provide considerable gain in brightness, but also serve as high-power sources of coherent radiation in new wavelength regions. In addition, for cases where the characteristics of a neodymium pump laser are close to the ultimate ones and there is no need to increase its brightness, the use of a Raman laser as an end cascade makes it possible to increase the efficiency of the whole laser system by several times. This opens new perspectives for creating laser systems with output energies 1 kJ and higher.

  17. Influence of a high-power pulsed ion beam on the mechanical properties of corundum ceramics (United States)

    Kostenko, V.; Pavlov, S.; Nikolaeva, S.


    The mechanical properties of near-surface layers of corundum ceramics treated by high-power pulsed ion beam of carbon are investigated. The samples for investigation were prepared from corundum substrate, which is usually used in microelectronic. The ion treatment was carried out at the TEMP-4M facility under the following conditions: an accelerating voltage of 160-200 keV, the current density in the pulse varied within 15-85 A/cm2. It was found that ion irradiation changes the structure and properties of near-surface layers of corundum ceramics. At the same time, melting and erosion of the surface layer takes place. These processes are accompanied by the formation of a network of microcracks. Microcracks are propagated only by the depth of melting layer. The mechanical properties were measured using a NanoTest600 nanohardness testing instrument. It was found that the nanohardness depends of the treatment modes. At a current density of 15A/cm2, with an increase treatment dose, the nanohardness of the irradiated surface layer increases in comparison with the initial value before irradiation. At higher current densities, the nanohardness of irradiated ceramics decreases relatively to the initial value before irradiation. The dependences of nanohardness off the irradiation dose in this case have the view of a curves with a minimum at irradiation doses of 2.5·1014 and 1.3·1014 cm-2, for current densities of 50 and 85 A/cm2, respectively.

  18. High-power ultraviolet 278 nm laser from fourth-harmonic generation of a Nd:YAG laser in CsB3O5. (United States)

    Wang, Zhichao; Yang, Feng; Zhang, Guochun; Bo, Yong; Liu, Shanshan; Xie, Shiyong; Xu, Yiting; Zong, Nan; Li, Fangqin; Liu, Biaolong; Xu, Jialin; Peng, Qinjun; Zhang, Jingyuan; Cui, Dafu; Wu, Yicheng; Xu, Zuyan


    We demonstrate a high-power UV 278 nm laser by fourth-harmonic generation (FHG) of a 1112 nm Nd:YAG laser in a nonlinear optical (NLO) crystal CsB3O5 (CBO) for the first time, to our best knowledge. A 30 W level diode-pumped Q-switched Nd:YAG laser at 1112 nm with beam quality factor M2=1.2 was used as the fundamental light source at a pulse width of 500 ns. With an LiB3O5 crystal, the 1112 nm laser was first frequency-doubled to 556 nm with an average output power of 13.5 W. It was then frequency doubled again in a CBO crystal to obtain the FHG output at 278 nm. The maximum average output power of the 278 nm laser is up to 1.5 W. The results demonstrated that CBO crystal is a promising NLO material for UV high-power lasers below 300 nm.

  19. Use of high-power diode lasers for hardening and thermal conduction welding of metals (United States)

    Klocke, Fritz; Demmer, Axel; Zaboklicki, A.


    CO2 and Nd:YAG high power lasers have become established as machining tools in industrial manufacturing over the last few years. The most important advantages compared to conventional processing techniques lie in the absence of forces introduced by the laser into the workpiece and in the simple arid highly accurate control in terms ofpositioning and timing making the laser a universally applicable, wear-free and extremely flexible tool /1,2/. The laser can be utilised costeffectively in numerous manufacturing processes but there are also further applications for the laser which produce excellent results from a technical point of view, but are not justified in terms of cost. The extensive use of lasers, particularly in small companies and workshops, is hindered by two main reasons: the complexity and size ofthe laser source and plant and the high investment costs /3/. A new generation of lasers, the high power diode lasers (HDL), combines high performance with a compact design, making the laser a cheap and easy to use tool with many applications /3,4,5,6/. In the diode laser, the laser beam is generated by a microelectronic diode which transforms electrical energy directly into laser energy. Diode lasers with low power outputs have, for some time, been making their mark in our everyday lives: they are used in CD players, laser printers and scanners at cash tills. Modern telecommunications would be impossible without these lasers which enable information to be transmitted in the form oflight impulses through optical fibres. They can also be found in compact precision measurement instrumentation - range fmders, interferometers and pollutant analysis devices /3,6/. In the field of material processing, the first applications ofthe laser, such as for soldering, inscribing, surface hardening and plastic or heat conduction welding, will exceed the limits ofthe relatively low performance output currently available. The diode laser has a shorter wavelength than the CO2 and

  20. Pulsed Power for Solid-State Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, W; Albrecht, G; Trenholme, J; Newton, M


    Beginning in the early 1970s, a number of research and development efforts were undertaken at U.S. National Laboratories with a goal of developing high power lasers whose characteristics were suitable for investigating the feasibility of laser-driven fusion. A number of different laser systems were developed and tested at ever larger scale in pursuit of the optimum driver for laser fusion experiments. Each of these systems had associated with it a unique pulsed power option. A considerable amount of original and innovative engineering was carried out in support of these options. Ultimately, the Solid-state Laser approach was selected as the optimum driver for the application. Following this, the Laser Program at the Lawrence Livermore National Laboratory and the University of Rochester undertook aggressive efforts directed at developing the technology. In particular, at Lawrence Livermore National Laboratory, a series of laser systems beginning with the Cyclops laser and culminating in the present with the National Ignition Facility were developed and tested. As a result, a large amount of design information for solid-state laser pulsed power systems has been documented. Some of it is in the form of published papers, but most of it is buried in internal memoranda, engineering reports and LLNL annual reports. One of the goals of this book is to gather this information into a single useable format, such that it is easily accessed and understood by other engineers and physicists for use with future designs. It can also serve as a primer, which when seriously studied, makes the subsequent reading of original work and follow-up references considerably easier. While this book deals only with the solid-state laser pulsed power systems, in the bibliography we have included a representative cross section of papers and references from much of the very fine work carried out at other institutions in support of different laser approaches. Finally, in recent years, there has

  1. High-power spectral beam combining of linearly polarized Tm:fiber lasers. (United States)

    Shah, Lawrence; Sims, R Andrew; Kadwani, Pankaj; Willis, Christina C C; Bradford, Joshua B; Sincore, Alex; Richardson, Martin


    To date, high-power scaling of Tm:fiber lasers has been accomplished by maximizing the power from a single fiber aperture. In this work, we investigate power scaling by spectral beam combination of three linearly polarized Tm:fiber MOPA lasers using dielectric mirrors with a steep transition from highly reflective to highly transmissive that enable a minimum wavelength separation of 6 nm between individual laser channels within the wavelength range from 2030 to 2050 nm. Maximum output power is 253 W with M(2)<2, ultimately limited by thermal lensing in the beam combining elements.

  2. Investigation of high-power diode-end-pumped Tm:YLF laser in slab geometry. (United States)

    Shen, Yingjie; Duan, Xiaoming; Yuan, Jinhe; Dai, Tongyu; Yao, Baoquan; Wang, Yuezhu


    Comparative investigations of high-power diode-end-pumped Tm:YLF laser with a-cut and c-cut slab crystals were demonstrated. A maximum output power of 87.5 W of 1907.8 nm Tm:YLF laser with two slab crystals was achieved, corresponding to a slope efficiency of 35.9% and an optical-to-optical efficiency of 32.1% with respect to the pump power. The c-cut slab Tm:YLF laser operated at 1907.8 nm with a beam quality factor of M2∼1.79 at the output power level of 71.0 W.

  3. Low-jitter and high-power 40 GHz all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin


    A novel design strategy for the epitaxial structure of monolithic mode-locked semiconductor lasers is presented. Using an all-active design, we fabricate 40-GHz lasers generating 2.8-ps almost chirp-free pulses with record low high-frequency jitter and more than 7-mW fiber coupled output power....

  4. The use of a high-power laser on swine mitral valve chordae tendineae. (United States)

    Pinto, Nathali Cordeiro; Chavantes, M Cristina; Zezell, Denise; Deana, Alessandro; Benetti, Carolina; Marcos, Rodrigo Labat; Lopes, Luciana Almeida; Martins, Rodrigo A B Lopes; Aiello, Vera Demarchi; Jatene, Fabio Biscegli; Pomerantzeff, Pablo M A


    Worldwide, rheumatic fever remains a significant cause of mitral valve insufficiency. It is responsible for approximately 90 % of early childhood valvular surgeries in Brazil. Elongated or flail chordae are frequently responsible and require surgical correction. The purpose of this study was to analyze and compare the histological tissues of the mitral valve chordae and the mechanical resistance generated by the chordae, both with and without the application of a high-power laser. Twenty normal porcine mitral valve chordae were measured and divided randomly into the following two groups: control group (not subjected to a high-power laser) and laser group (subjected to photonic irradiation). Laser surgery was performed under controlled conditions, using following parameters: λ = 980-nm wavelength, power = 3 W, and energy = 60 J. A mechanical test machine was used in combination with a subsequent histological study to measure chordae tensile properties. A histological analysis demonstrated a typical collagen bundle arrangement in the control group; however, under a particular reached temperature range (48), the collagen bundles assumed different arrangements in the laser group. Significant reductions in the chordae tendineae lengths and changes in their resistance in the laser group were observed, as these chordae exhibited less rigid fibers. The chordae tendineae of normal porcine valves subjected to a high-power laser exhibited its length reduction and less stiffness compared to the control group. A histological analysis of the laser treatment specimens demonstrated differences in collagen bundle spatial organization, following slight changes into tissue temperature.

  5. High-power direct green laser oscillation of 598 mW in Pr(3+)-doped waterproof fluoroaluminate glass fiber excited by two-polarization-combined GaN laser diodes. (United States)

    Nakanishi, Jun; Horiuchi, Yuya; Yamada, Tsuyoshi; Ishii, Osamu; Yamazaki, Masaaki; Yoshida, Minoru; Fujimoto, Yasushi


    We demonstrated a high-power and highly efficient Pr-doped waterproof fluoride glass fiber laser at 522.2 nm excited by two-polarization-combined GaN laser diodes and achieved a subwatt output power of 598 mW and slope efficiency of 43.0%. This system will enable us to make a vivid laser display, a photocoagulation laser for eye surgery, a color confocal scanning laser microscope, and an effective laser for material processing. Direct visible ultrashort pulse generation is also expected. © 2011 Optical Society of America

  6. Control and performance improvements of a pulse compressor in use for testing accelerating structures at high power (United States)

    Woolley, Benjamin; Syratchev, Igor; Dexter, Amos


    New developments relating to compact X-band, SLED-I type pulse compressors being developed at CERN for testing high gradient structures are described. Pulse compressors of interest take rf pulses from one or more high power klystrons with duration typically >1.5 μ s and deliver up to 5 times the input power for a shorter duration operation with low level rf (LLRF) control have been developed. Input drive amplitude and phase for each pulse is evolved with a control algorithm from the pulse compressor output for previous pulses. The goal is to deliver precise amplitude for pulses to test stands and precise amplitude and phase for pulses to accelerator systems. Control algorithms have been developed and validated experimentally.

  7. Monocrystalline CVD-diamond optics for high-power laser applications (United States)

    Holly, C.; Traub, M.; Hoffmann, D.; Widmann, C.; Brink, D.; Nebel, C.; Gotthardt, T.; Sözbir, M. C.; Wenzel, C.


    The potential of diamond as an optical material for high-power laser applications in the wavelength regime from the visible spectrum (VIS) to the near infrared (NIR) is investigated. Single-crystal diamonds with lateral dimensions up to 7×7mm2 are grown with microwave plasma assisted chemical vapor deposition (MPACVD) in parallel with up to 60 substrates and are further processed to spherical optics for beam guidance and shaping. The synthetic diamonds offer superior thermal, mechanical and optical properties, including low birefringence, scattering and absorption, also around 1 μm wavelength. We present dielectric (AR and HR) coated single-crystal diamond optics which are tested under high laser power in the multi-kW regime. The thermally induced focal shift of the diamond substrates is compared to the focal shift of a standard collimating and focusing unit for laser cutting made of fused silica optics. Due to the high thermal conductivity and low absorption of the diamond substrates compared to the fused silica optics no additional focal shift caused by a thermally induced refractive index change in the diamond is observed in our experiments. We present experimental results regarding the performance of the diamond substrates with and without dielectric coatings under high power and the influences of growth induced birefringence on the optical quality. Finally, we discuss the potential of the presented diamond lenses for high-power applications in the field of laser materials processing.

  8. Absorption of irrigation fluid occurs frequently during high power 532 nm laser vaporization of the prostate. (United States)

    Hermanns, Thomas; Grossmann, Nico C; Wettstein, Marian S; Fankhauser, Christian D; Capol, Janine C; Poyet, Cédric; Hefermehl, Lukas J; Zimmermann, Matthias; Sulser, Tullio; Müller, Alexander


    Absorption of irrigation fluid was not detected during GreenLight™ laser vaporization of the prostate using the first generation 80 W laser. However, data are lacking on intraoperative irrigation fluid absorption using the second generation 120 W high power laser. We assessed whether fluid absorption occurs during high power laser vaporization of the prostate. We performed this prospective investigation at a tertiary referral center in patients undergoing 120 W laser vaporization for prostatic bladder outlet obstruction. Normal saline containing 1% ethanol was used for intraoperative irrigation. The expired breath ethanol concentration was measured periodically during the operation using an alcometer. The volume of saline absorption was calculated from these concentrations. Intraoperative changes in hematological and biochemical blood parameters were also recorded. Of 50 investigated patients 22 (44%) had a positive breath ethanol test. Median absorption volume in the absorber group was 725 ml (range 138 to 3,452). Ten patients absorbed more than 1,000 ml. Absorbers had a smaller prostate, more capsular perforation, higher bleeding intensity and more laser energy applied during the operation. Three patients (13%) had symptoms potentially related to fluid absorption. Hemoglobin, hematocrit and serum chloride were the only blood parameters that changed significantly in the absorber group. The changes were significantly different than those in nonabsorbers. Fluid absorption occurs frequently during high power laser vaporization of the prostate. This should be considered in patients who present with cardiopulmonary or neurological symptoms during or after the procedure. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  9. Dynamics of defects in Ce³⁺ doped silica affecting its performance as protective filter in ultraviolet high-power lasers. (United States)

    Demos, Stavros G; Ehrmann, Paul R; Qiu, S Roger; Schaffers, Kathleen I; Suratwala, Tayyab I


    We investigate defects forming in Ce³⁺-doped fused silica samples following exposure to nanosecond ultraviolet laser pulses and their relaxation as a function of time and exposure to low intensity light at different wavelengths. A subset of these defects are responsible for inducing absorption in the visible and near infrared spectral range, which is of critical importance for the use of this material as ultraviolet light absorbing filter in high power laser systems. The dependence of the induced absorption as a function of laser fluence and methods to most efficiently mitigate this effect are presented. Experiments simulating the operation of the material as a UV protection filter for high power laser systems were performed in order to determine limitations and practical operational conditions.

  10. Process control in continuous high-power CO2 laser beam welding (United States)

    Seidel, Bernd; Beersiek, Jorg; Beyer, Eckhard


    The use of high power CO2 lasers in welding enables processing with high laser intensities at the workpiece which is connected with the formation of a laser induced plasma at the surface of the workpiece. Therefore the effect of deep penetration welding by formation of a plasma filled keyhole and plasma plume above the workpiece is possible, including the risk of plasma shielding, which means strong absorption of the incident laser beam above the workpiece and thus interruption of the welding process. The conditions for ignition of plasma shielding, which is determined by electron density, are mainly influenced by laser intensity, process gas and material. Variations of these parameters have been conducted in order to find limits for the appearance of plasma shielding. Experimental data are used to verify a model concerning the absorption mechanism of a stationary shielding plasma state. The dynamic behavior is treated by time resolved spectroscopic analysis of the light emitted by the plasma above the workpiece yielding monitoring signals that have a strong correlation with the formation of plasma shielding. Based on these investigations a closed-loop process control in continuous high power laser welding has been developed. Using the intensity of a spectral line of laser induced plasma as monitoring signal and the regulation of laser intensity via laser power, plasma shielding can be suppressed. From the industrial point of view increase in economy and reliability of the laser welding process combined with quality improvements which are induced by the application of the plasma shielding controller (PSC) are of great importance. For this reason three examples of PSC application are presented.

  11. High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints (United States)

    Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

    According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

  12. Generation of titanium-oxide nanoparticles in liquid using a high-power, high-brightness continuous-wave fiber laser (United States)

    Abdolvand, A.; Khan, S. Z.; Yuan, Y.; Crouse, P. L.; Schmidt, M. J. J.; Sharp, M.; Liu, Zhu; Li, Lin


    Previous studies on laser-assisted nanomaterial formation in liquids have focused on using pulsed laser ablation of metals. We report, for the first time to our knowledge, the fabrication of nanoparticles via high-power high-brightness continuous-wave fiber laser ablation of titanium in liquids. Analysis revealed the generation of spherical nanoparticles of titanium-oxide ranging mainly between 5 nm and 60 nm in diameter. A mechanism of formation for crystallized nanoparticles, based on the self-organized pulsations of the evaporated metal, is proposed. This may account for the observed substantial efficiency gain owing to the high average power and brightness of the source.

  13. Feasibility Experiments on the Demilitarization of Chemical Munitions by High Power Lasers. Part I. Cutting Experiments (United States)


    this report may be obtained from the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22151. 4 I The findings...Project Maneger for Chemical Demilitarization and Installation Restoration UNCLASSIFIED Aberdeen Proving Ground, Ma-yland 21010 15a. DECLASSIFICATION... information on the economics of high power lasers in industrial applications. As a result of these preliminary discussions, it was decided to perform

  14. Design and test of frequency tuner for CAEP high power THz free-electron laser


    Mi, Zhenghui; Sun, Yi; Pan, Weimin; Lin, Haiying; Zhao, Danyang; Lu, Xiangyang; Quan, Shengwen; Luo, Xing; Li, Ming; Yang, Xingfan; Wang, Guangwei; Dai, Jianping; Li, Zhongquan; Ma, Qiang; Sha, Peng


    Peking University is developing a 1.3 GHz superconducting accelerating section for China Academy of Engineering Physics (CAEP) high power THz free-electron laser. A compact fast/slow tuner has developed by Institute of High Energy Physics (IHEP) for the accelerating section, to control Lorentz detuning, beam loading effect, compensate for microphonics and liquid Helium pressure fluctuations. The tuner design, warm test and cold test of the first prototype are presented.

  15. A thermo-field bimetal deformable mirror for wavefront correction in high power lasers (United States)

    Huang, L.; Xue, Q.; Yan, P.; Gong, M. L.; Li, T. H.; Feng, Z. X.; Ma, X. K.


    A novel thermo-field bimetal deformable mirror (TBDM) is proposed, which is mainly composed of a face plate, a base plate and some thermal elements, such as thermoelectric coolers (TECs). The TBDM utilizes the continuous thermal field to bend the face plate, via the TECs heating or cooling. A prototype is described, and the first results are presented. The simplicity and ultra-low cost make the TBDM attractive in correcting aberrations in high power lasers.

  16. Review of self-focusing of high power lasers in large-mode-area optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Chujun; Li Ying; Lei Dajun; Yang Hua; Wen Shuangchun; Fan Dianyuan; Wen Jianguo, E-mail: [Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education, School of Computer and Communication, Hunan University, Changsha 410082 (China)


    The main progress about the self-focusing of high power lasers in large-mode-area optical fiber has been reviewed. The theoretical models including the self-focusing effects have been discussed. Some different views on the whole beam self focusing and small scale self-focusing effects in optical fiber have been introduced. Moreover, the possible methods exceeding the bulk-media self-focusing threshold have been discussed and explored.

  17. The modeling of thermal fields in high power multi-disk cryogenic laser amplifier (United States)

    Petrov, V. A.; Kuptsov, G. V.; Petrov, V. V.; Kirpichnikov, A. V.; Laptev, A. V.; Pestryakov, E. V.


    In this paper we focus on the second unit of multipass amplification of the cryogenic diode-pumped high power laser system operating at 1 kHz repetition rate. Thermal fields in the cooling system of the amplifier were calculated and compared with experimental data. Numerical algorithm based on 3+1D heat transfer equation is proposed. The results of modeling are discussed and analyzed.

  18. Gravitational wave generation by interaction of high power lasers with matter. Part I: Shock wave model

    CERN Document Server

    Kadlecová, Hedvika; Weber, Stefan; Korn, Georg


    We analyze theoretical models of gravitational wave generation in the interaction of high power lasers with matter in linear approximation of gravitational theory. We derive the analytical formulas and estimates for the metric perturbations and the radiated power of the generated gravitational waves. Furthermore we investigate the characteristics of polarization and the behavior of test particles in the presence of gravitational wave which will be important for the detection.

  19. Industrial mJ-class all-fiber front end with spatially coherent top-hat beam output used as seeder for high power laser (United States)

    Gleyze, Jean-François; Perrin, A.; Calvet, Pierre; Gouriou, Pierre; Scol, Florent; Valentin, Constance; Bouwmans, Géraud; Lecren, E.; Hugonnot, Emmanuel


    In large scale laser facility dedicated to laser-matter interaction including inertial confinement fusion, such as LMJ or NIF, high-energy main amplifier is injected by a laser source in which the beam parameters must be controlled. For many years, the CEA has developed nano-joule pulses all-fiber front end sources, based on the telecommunications fiber optics technologies. Thanks to these technologies, we have been able to precisely control temporal shaping and phase-modulated pulse. Nowadays, fiber lasers are able to deliver very high power beams and high energy pulses for industrial needs (laser marking, welding,…). Therefore, we have currently developed new nanosecond pulses fibered amplifiers able to increase output pulse energy up to the mJ level. These amplifiers are based on flexible fibers and not on rod type. This allows us to achieve a compact source. Nevertheless the intensity profile of theses fibers usually has a Gaussian shape. To be compatible with main amplifier section injection, the Gaussian intensity profile must then be transformed into `top-hat' profile. To reach the goal, we have recently developed an elegant and efficient solution based on a single-mode fiber which directly delivers a spatially coherent `top-hat' beam. In the conference, we will present this mJ-class top-hat all-fiber laser system, the results and the industrial prototype which can be used as a front-end of high-power lasers or as a seeder for other types of lasers.

  20. High-efficiency, high-power and low threshold Yb3+:YAG ceramic laser. (United States)

    Pirri, Angela; Alderighi, Daniele; Toci, Guido; Vannini, Matteo


    We present a high-power, high-efficiency and low threshold laser prototype based on doped ceramic Yb(3+):YAG. We achieved an output power of 9 W with a slope efficiency of 73% and a threshold of 1 W at 1030 nm in quasi-Continuous Wave (QCW). Moreover, we obtained an output power 7.7 W with a slope efficiency of 60% in Continuous Wave (CW). Finally, a characterization of a low losses tunable cavity for several laser wavelengths with an output power exceeding 5 W is reported.

  1. The impact of external optical feedback on the degradation behavior of high-power diode lasers

    DEFF Research Database (Denmark)

    Hempel, Martin; Chi, Mingjun; Petersen, Paul Michael


    The impact of external feedback on high-power diode laser degradation is studied. For this purpose early stages of gradual degradation are prepared by accelerated aging of 808-nm-emitting AlGaAs-based devices. While the quantum well that actually experiences the highest total optical load remains...... unaffected, severe impact is observed to the cladding layers and the waveguide. Consequently hardening of diode lasers for operation under external optical feedback must necessarily involve claddings and waveguide, into which the quantum well is embedded....

  2. Thermal properties of high-power diode lasers investigated by means of high resolution thermography

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowska, Anna, E-mail: [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland); Malag, Andrzej; Dabrowska, Elzbieta; Teodorczyk, Marian [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland)


    In the present work, thermal effects in high-power diode lasers are investigated by means of high resolution thermography. Thermal properties of the devices emitting in the 650 nm and 808 nm wavelength ranges are compared. The different versions of the heterostructure design are analyzed. The results show a lowering of active region temperature for diode lasers with asymmetric heterostructure scheme with reduced quantum well distance from the heterostructure surface (and the heat sink). Optimization of technological processes allowed for the improvement of the device performance, e.g. reduction of solder non-uniformities and local defect sites at the mirrors which was visualized by the thermography.

  3. Diffraction Effects in Measurements of Characteristics of High-Power Microwave Pulses with Wide-Aperture Liquid Calorimeters (United States)

    Klimov, A. I.; Tot'meninov, E. M.


    Numerical nonstationary simulation of diffraction by a quasi-plane three-layer wide-aperture absorbing loads of liquid calorimeters intended for measuring the energy of high-power microwave radiation pulses is performed using the electromagnetic code KARAT with application to the S-band. It is shown that these effects can cause significant distortion of the microwave pulse shape behind the load as well as underestimation of the measured energy by 10-20%.

  4. A compact ultranarrow high-power laser system for experiments with 578 nm ytterbium clock transition. (United States)

    Cappellini, G; Lombardi, P; Mancini, M; Pagano, G; Pizzocaro, M; Fallani, L; Catani, J


    In this paper, we present the realization of a compact, high-power laser system able to excite the ytterbium clock transition at 578 nm. Starting from an external-cavity laser based on a quantum dot chip at 1156 nm with an intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of visible light at 578 nm via frequency doubling. The laser is locked with a 500 kHz bandwidth to an ultra-low-expansion glass cavity stabilized at its zero coefficient of thermal expansion temperature through an original thermal insulation and correction system. This laser allowed the observation of the clock transition in fermionic (173)Yb with a <50 Hz linewidth over 5 min, limited only by a residual frequency drift of some 0.1 Hz/s.

  5. A compact ultranarrow high-power laser system for experiments with 578 nm ytterbium clock transition

    Energy Technology Data Exchange (ETDEWEB)

    Cappellini, G., E-mail: [LENS European Laboratory for Nonlinear Spectroscopy, 50019 Sesto Fiorentino (Italy); Lombardi, P. [Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino (Italy); INO-CNR Istituto Nazionale di Ottica del CNR, Sezione di Sesto Fiorentino, 50019 Sesto Fiorentino (Italy); Mancini, M.; Pagano, G. [Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino (Italy); Pizzocaro, M. [INRIM Istituto Nazionale di Ricerca Metrologica, Torino 10135 (Italy); Fallani, L. [LENS European Laboratory for Nonlinear Spectroscopy, 50019 Sesto Fiorentino (Italy); Department of Physics and Astronomy, University of Florence, 50019 Sesto Fiorentino (Italy); Catani, J. [LENS European Laboratory for Nonlinear Spectroscopy, 50019 Sesto Fiorentino (Italy); INO-CNR Istituto Nazionale di Ottica del CNR, Sezione di Sesto Fiorentino, 50019 Sesto Fiorentino (Italy)


    In this paper, we present the realization of a compact, high-power laser system able to excite the ytterbium clock transition at 578 nm. Starting from an external-cavity laser based on a quantum dot chip at 1156 nm with an intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of visible light at 578 nm via frequency doubling. The laser is locked with a 500 kHz bandwidth to an ultra-low-expansion glass cavity stabilized at its zero coefficient of thermal expansion temperature through an original thermal insulation and correction system. This laser allowed the observation of the clock transition in fermionic {sup 173}Y b with a <50 Hz linewidth over 5 min, limited only by a residual frequency drift of some 0.1 Hz/s.

  6. Recent developments in high power 2.3-2.4 μm diode lasers (United States)

    Shterengas, L.; Belenky, G.; Kisin, M.; Donetsky, D.; Westerfeld, D.


    Mid-infrared light emitters capable of room temperature continuous-wave (CW) operation are in demand for variety of applications ranging from medical diagnostics to missile countermeasures. Room temperature type-I quantum-well (QW) GaSb-based lasers, laser arrays and light emitting diodes operating in the spectral range from below 2 to over 3μm have been reported. The maximum CW output power from 1cm-wide 2.35μm linear laser array was 10 W, in quasi-CW operation (30 μs pulse, 300 Hz pulse repetition frequency) the maximum measured power is 18.5 W. In short pulse operation heating is negligible, and the light-current characteristics remains linear to beyond 20 W at 100 A.

  7. Numerical investigation on high power mid-infrared supercontinuum fiber lasers pumped at 3 µm. (United States)

    Wei, Chen; Zhu, Xiushan; Norwood, Robert A; Song, Feng; Peyghambarian, N


    High power mid-infrared (mid-IR) supercontinuum (SC) laser sources in the 3-12 µm region are of great interest for a variety of applications in many fields. Although various mid-IR SC laser sources have been proposed and investigated experimentally and theoretically in the past several years, power scaling of mid-IR SC lasers beyond 3 μm with infrared edges extending beyond 7 μm are still challenges because the wavelengths of most previously used pump sources are below 2 μm. These problems can be solved with the recent development of mode-locked fiber lasers at 3 μm. In this paper, high power mid-IR SC laser sources based on dispersion engineered tellurite and chalcogenide fibers and pumped by ultrafast lasers at 3 µm are proposed and investigated. Our simulation results show that, when a W-type tellurite fiber with a zero dispersion wavelength (ZDW) of 2.7 µm is pumped at 2.78 μm, the power proportion of the SC laser beyond 3 µm can exceed 40% and the attainable SC output power of the proposed solid-cladding tellurite fiber is one order of magnitude higher than that of existing microstructured tellurite fibers. Our calculation also predicts that a very promising super-broadband mid-IR SC fiber laser source covering two atmospheric windows and molecules' "fingerprint" region can be obtained with a microstructured As2Se3 chalcogenide fiber pumped at 2.78 μm.

  8. Characterization and performance of a high-power solid-state laser for a high-current photo-cathode injector

    Energy Technology Data Exchange (ETDEWEB)

    Shukui Zhang; David Hardy; George Neil; Michelle D. Shinn


    We report the characterization and performance of a diode-pumped, high-power, picosecond laser system designed for high-current photo-cathode accelerator injector at repetition rates of both 75MHz and 750MHz. The characterization includes measurement of the amplification gain, thermally induced beam mode variation, harmonic conversion efficiency, system's amplitude stability, beam pointing stability, beam profile, and pulse width for both frequencies.

  9. High-power fiber laser cutting parameter optimization for nuclear Decommissioning

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Lopez


    Full Text Available For more than 10 years, the laser process has been studied for dismantling work; however, relatively few research works have addressed the effect of high-power fiber laser cutting for thick sections. Since in the nuclear sector, a significant quantity of thick material is required to be cut, this study aims to improve the reliability of laser cutting for such work and indicates guidelines to optimize the cutting procedure, in particular, nozzle combinations (standoff distance and focus position, to minimize waste material. The results obtained show the performance levels that can be reached with 10 kW fiber lasers, using which it is possible to obtain narrower kerfs than those found in published results obtained with other lasers. Nonetheless, fiber lasers appear to show the same effects as those of CO2 and ND:YAG lasers. Thus, the main factor that affects the kerf width is the focal position, which means that minimum laser spot diameters are advised for smaller kerf widths.

  10. High-power fiber laser cutting parameter optimization for nuclear decommissioning

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Ana Beatriz; Assuncao, Eurico; Quintino, Luisa [IDMEC, Instituto Superior Tecnico, Universidade de Lisboa, Lisboa (Portugal); Khan, Ali; Blackbun, Jonathan [TWI Ltd., Cambridge (United States)


    For more than 10 years, the laser process has been studied for dismantling work; however, relatively few research works have addressed the effect of high-power fiber laser cutting for thick sections. Since in the nuclear sector, a significant quantity of thick material is required to be cut, this study aims to improve the reliability of laser cutting for such work and indicates guidelines to optimize the cutting procedure, in particular, nozzle combinations (standoff distance and focus position), to minimize waste material. The results obtained show the performance levels that can be reached with 10 kW fiber lasers, using which it is possible to obtain narrower kerfs than those found in published results obtained with other lasers. Nonetheless, fiber lasers appear to show the same effects as those of CO{sub 2} and ND:YAG lasers. Thus, the main factor that affects the kerf width is the focal position, which means that minimum laser spot diameters are advised for smaller kerf widths.

  11. All-Solid-State Drivers for High Power Excimer Lasers Used in Projection Gas Immersion Laser Doping

    National Research Council Canada - National Science Library

    Jacob, Jonah


    .... P-GILD uses a pulsed, 200-watt-class excimer laser as an illumination source to produce ultra-shallow, low-sheet resistance, box-like and retrograde impurity profiles in silicon without the use...

  12. Low jitter and high power all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin


    A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and -coupled power of 7 mW.......A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and -coupled power of 7 mW....

  13. Low jitter and high power all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin


    A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and fiber-coupled power of 7 mW.......A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and fiber-coupled power of 7 mW....

  14. High power gain switched laser diodes using a novel compact picosecond switch based on a GaAs bipolar junction transistor structure for pumping (United States)

    Vainshtein, Sergey; Kostamovaara, Juha


    A number of up-to-date applications, including advanced optical radars with high single-shot resolution, precise 3 D imaging, laser tomography, time imaging spectroscopy, etc., require low-cost, compact, reliable sources enabling the generation of high-power (1-100 W) single optical pulses in the picosecond range. The well-known technique of using the gain-switching operation mode of laser diodes to generate single picosecond pulses in the mW range fails to generate high-power single picosecond pulses because of a lack of high-current switches operating in the picosecond range. We report here on the achieving of optical pulses of 45W / 70ps, or alternatively 5W / 40ps, with gain-switched commercial quantum well (QW) laser diodes having emitting areas of 250 × 200 μm and 75 × 2 μm, respectively. This was made possible by the use of a novel high-current avalanche switch based on a GaAs bipolar junction transistor (BJT) structure with a switching time (transistor structure.) A simulation code developed earlier but modified and carefully verified here allowed detailed comparison of the experimental and simulated laser responses and the transient spectrum.

  15. Experimental demonstration of a compact epithermal neutron source based on a high power laser (United States)

    Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Raspino, D.; Ansell, S.; Wilson, L. A.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Kelleher, J.; Murphy, C. D.; Notley, M.; Rusby, D. R.; Schooneveld, E.; Borghesi, M.; McKenna, P.; Rhodes, N. J.; Neely, D.; Brenner, C. M.; Kar, S.


    Epithermal neutrons from pulsed-spallation sources have revolutionised neutron science allowing scientists to acquire new insight into the structure and properties of matter. Here, we demonstrate that laser driven fast (˜MeV) neutrons can be efficiently moderated to epithermal energies with intrinsically short burst durations. In a proof-of-principle experiment using a 100 TW laser, a significant epithermal neutron flux of the order of 105 n/sr/pulse in the energy range of 0.5-300 eV was measured, produced by a compact moderator deployed downstream of the laser-driven fast neutron source. The moderator used in the campaign was specifically designed, by the help of MCNPX simulations, for an efficient and directional moderation of the fast neutron spectrum produced by a laser driven source.

  16. Feasibility of High-Power Diode Laser Array Surrogate to Support Development of Predictive Laser Lethality Model

    Energy Technology Data Exchange (ETDEWEB)

    Lowdermilk, W H; Rubenchik, A M; Springer, H K


    Predictive modeling and simulation of high power laser-target interactions is sufficiently undeveloped that full-scale, field testing is required to assess lethality of military directed-energy (DE) systems. The cost and complexity of such testing programs severely limit the ability to vary and optimize parameters of the interaction. Thus development of advanced simulation tools, validated by experiments under well-controlled and diagnosed laboratory conditions that are able to provide detailed physics insight into the laser-target interaction and reduce requirements for full-scale testing will accelerate development of DE weapon systems. The ultimate goal is a comprehensive end-to-end simulation capability, from targeting and firing the laser system through laser-target interaction and dispersal of target debris; a 'Stockpile Science' - like capability for DE weapon systems. To support development of advanced modeling and simulation tools requires laboratory experiments to generate laser-target interaction data. Until now, to make relevant measurements required construction and operation of very high power and complex lasers, which are themselves costly and often unique devices, operating in dedicated facilities that don't permit experiments on targets containing energetic materials. High power diode laser arrays, pioneered by LLNL, provide a way to circumvent this limitation, as such arrays capable of delivering irradiances characteristic of De weapon requires are self-contained, compact, light weight and thus easily transportable to facilities, such as the High Explosives Applications Facility (HEAF) at Lawrence Livermore National Laboratory (LLNL) where testing with energetic materials can be performed. The purpose of this study was to establish the feasibility of using such arrays to support future development of advanced laser lethality and vulnerability simulation codes through providing data for materials characterization and laser

  17. Laser processes and analytics for high power 3D battery materials (United States)

    Pfleging, W.; Zheng, Y.; Mangang, M.; Bruns, M.; Smyrek, P.


    Laser processes for cutting, modification and structuring of energy storage materials such as electrodes, separator materials and current collectors have a great potential in order to minimize the fabrication costs and to increase the performance and operational lifetime of high power lithium-ion-batteries applicable for stand-alone electric energy storage devices and electric vehicles. Laser direct patterning of battery materials enable a rather new technical approach in order to adjust 3D surface architectures and porosity of composite electrode materials such as LiCoO2, LiMn2O4, LiFePO4, Li(NiMnCo)O2, and Silicon. The architecture design, the increase of active surface area, and the porosity of electrodes or separator layers can be controlled by laser processes and it was shown that a huge impact on electrolyte wetting, lithium-ion diffusion kinetics, cell life-time and cycling stability can be achieved. In general, the ultrafast laser processing can be used for precise surface texturing of battery materials. Nevertheless, regarding cost-efficient production also nanosecond laser material processing can be successfully applied for selected types of energy storage materials. A new concept for an advanced battery manufacturing including laser materials processing is presented. For developing an optimized 3D architecture for high power composite thick film electrodes electrochemical analytics and post mortem analytics using laser-induced breakdown spectroscopy were performed. Based on mapping of lithium in composite electrodes, an analytical approach for studying chemical degradation in structured and unstructured lithium-ion batteries will be presented.

  18. High-power passively mode-locked Nd:YVO(4) laser using SWCNT saturable absorber fabricated by dip coating method. (United States)

    Tang, Chun Yin; Chai, Yang; Long, Hui; Tao, Lili; Zeng, Long Hui; Tsang, Yuen Hong; Zhang, Ling; Lin, Xuechun


    Passive mode locked laser is typically achieved by the Semiconductor Saturable absorber Mirror, SESAM, saturable absorber, which is produced by expensive and complicated metal organic chemical vapor deposition method. Carbon based single wall carbon nanotube (SWCNT), saturable absorber, is a promising material which is capable to produce stable passive mode-locking in the high power laser cavity over a wide operational wavelength range. This study has successfully demonstrated the high power mode locking laser system operating at 1 micron by using SWCNT based absorbers fabricated by dip coating method. The proposed fabrication method is practical, simple and cost effective for fabricating SWCNT saturable absorber. The demonstrated high power Nd:YVO(4) mode-locked laser operating at 1064nm have maximum output power up to 2.7W,with the 167MHz repetition rate and 3.1 ps pulse duration, respectively. The calculated output pulse energy and peak power are 16.1nJ and 5.2kW, respectively.

  19. Numerical study of high-power semiconductor lasers for operation at sub-zero temperatures (United States)

    Hasler, K. H.; Frevert, C.; Crump, P.; Erbert, G.; Wenzel, H.


    We present results on the impact of the Al-content in the waveguide structure on the electro-optical characteristics of 9xx nm, GaAs-based high-power lasers operated at room (300 K) and at sub-zero (200 K) heat sink temperatures. Experimentally a strong improvement of conversion efficiency and output power has been found if the lasers are cooled down. Numerical simulations using a software tool which solves the thermo-dynamic based drift-diffusion equations are able to reproduce the experimental findings. The reasons for the improved performance at lower temperatures are the enhancement of the modal gain and the reduced accumulation of electrons in the p-confinement layers resulting in a reduction of the leakage current. The latter allows the realization of lasers with a reduced Al content having a smaller series resistance and thus further enlarged conversion efficiency at sub-zero temperatures.

  20. High power, 1060-nm diode laser with an asymmetric hetero-waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Li, T; Zhang, Yu [National Key Lab. On High Power Diode Laser,Changchun University of Science and Technology,Changchun, 130033 (China); Hao, E [College of Physics, Jilin University, Changchun, 130021 (China)


    By introducing an asymmetric hetero-waveguide into the epitaxial structure of a diode laser, a 6.21-W output is achieved at a wavelength of 1060 nm. A different design in p- and n-confinement, based on optimisation of energy bands, is used to reduce voltage loss and meet the requirement of high power and high wall-plug efficiency. A 1060-nm diode laser with a single quantum well and asymmetric hetero-structure waveguide is fabricated and analysed. Measurement results show that the asymmetric hetero-structure waveguide can be efficiently used for reducing voltage loss and improving the confinement of injection carriers and wall-plug efficiency. (lasers)

  1. High-power fiber-coupled 100W visible spectrum diode lasers for display applications (United States)

    Unger, Andreas; Küster, Matthias; Köhler, Bernd; Biesenbach, Jens


    Diode lasers in the blue and red spectral range are the most promising light sources for upcoming high-brightness digital projectors in cinemas and large venue displays. They combine improved efficiency, longer lifetime and a greatly improved color space compared to traditional xenon light sources. In this paper we report on high-power visible diode laser sources to serve the demands of this emerging market. A unique electro-optical platform enables scalable fiber coupled sources at 638 nm with an output power of up to 100 W from a 400 μm NA0.22 fiber. For the blue diode laser we demonstrate scalable sources from 5 W to 100 W from a 400 μm NA0.22 fiber.

  2. High power, high efficiency continuous-wave 808 nm laser diode arrays (United States)

    Wang, Zhenfu; Li, Te; Yang, Guowen; Song, Yunfei


    The continuous-wave 100 W-class 808 nm laser diode arrays with extremely high power conversion efficiency of 68% were reported at the heatsink temperature of 25 °C. To the best of our knowledge, this was the highest power conversion efficiency at continuous-wave 106 W 808 nm laser diode array with 50% fill factor so far. An asymmetric broad waveguide epitaxial structure with very low internal optical loss of 0.5 cm-1 was presented. In order to improve the efficiency, various fill factor devices were studied. The 50 W laser diode array with 30% fill factoir and 1.0 mm cavity length demonstrated power conversion efficiency of 71% at heatsink temperature of 15 °C.

  3. Wavelength diversification of high-power external cavity diamond Raman lasers using intracavity harmonic generation. (United States)

    Jasbeer, Hadiya; Williams, Robert J; Kitzler, Ondrej; McKay, Aaron; Mildren, Richard P


    We report a high power quasi-continuous-wave (QCW) 620 nm laser from an external cavity diamond Raman laser utilizing intracavity frequency doubling in lithium triborate. Output power of 30 W for durations of 0.25 ms at 15% conversion efficiency was achieved with a beam quality factor M2 = 1.1 from a free-running Nd:YAG pump laser of M2 = 1.5. The critical design parameters that affect conversion efficiency and power were analysed with the aid of an analytical model. By adaptation to other pump technologies, the diamond approach provides a novel pathway towards high brightness CW beam generation in the visible and ultraviolet regions.

  4. High power fiber coupled diode lasers for display and lighting applications (United States)

    Drovs, Simon; Unger, Andreas; Dürsch, Sascha; Köhler, Bernd; Biesenbach, Jens


    The performance of diode lasers in the visible spectral range has been continuously improved within the last few years, which was mainly driven by the goal to replace arc lamps in cinema or home projectors. In addition, the availability of such high power visible diode lasers also enables new applications in the medical field, but also the usage as pump sources for other solid state lasers. This paper summarizes the latest developments of fiber coupled sources with output power from 1.4 W to 120 W coupled into 100 μm to 400 μm fibers in the spectral range around 405 nm and 640 nm. New developments also include the use of fiber coupled multi single emitter arrays at 450 nm, as well as very compact modules with multi-W output power.

  5. Low noise control and wavelength shift of high-power DFB laser (United States)

    Tian, Yuan; Yang, Junjie; Lai, Xui; Zhang, Shu; Chen, Jiaqi; Li, Jingxuan; Sui, Guorong


    This letter reports the low noise control and wavelength shift of a commercial fixed-wavelength high-power DFB laser emitting at 785 nm. In this control system, a novel current driving module integrated with PID temperature controller is designed to provide precise injection current and stable operating temperature. The start- up and stop characteristic of this system is improved as well, to optimize output response and extend service life of the DFB laser. Experimental results show that the optical output power can be accurately controlled in the range of 0 to 600 mW, with the stability better than 2 ‰. In addition, we could effectively control the center wavelength from 785 nm to 793 nm maintaining the linewidth less than 0.9 nm. The research will enhance the performance and extend the use of present commercial DFB laser.

  6. High power density vertical-cavity surface-emitting lasers with ion implanted isolated current aperture. (United States)

    Higuchi, Akira; Naito, Hideyuki; Torii, Kousuke; Miyamoto, Masahiro; Morita, Takenori; Maeda, Junya; Miyajima, Hirofumi; Yoshida, Harumasa


    We report on GaAs-based high power density vertical-cavity surface-emitting laser diodes (VCSELs) with ion implanted isolated current apertures. A continuous-wave output power of over 380 mW and the power density of 4.9 kW/cm2 have been achieved at 15 °C from the 100-μm-diameter aperture, which is the highest output characteristic ever reported for an ion implanted VCSEL. A high background suppression ratio of over 40 dB has also been obtained at the emission wavelength of 970 nm. The ion implantation technique provides an excellent current isolation in the apertures and would be a key to realize high power output from a VCSEL array.

  7. Directed high-power THz radiation from transverse laser wakefield excited in an electron density filament (United States)

    Kalmykov, Serge; Englesbe, Alexander; Elle, Jennifer; Domonkos, Matthew; Schmitt-Sody, Andreas


    A tightly focused femtosecond, weakly relativistic laser pulse partially ionizes the ambient gas, creating a string (a ``filament'') of electron density, locally reducing the nonlinear index and compensating for the self-focusing effect caused by bound electrons. While maintaining the filament over many Rayleigh lengths, the pulse drives inside it a three-dimensional (3D) wave of charge separation - the plasma wake. If the pulse waist size is much smaller than the Langmuir wavelength, electron current in the wake is mostly transverse. Electrons, driven by the wake across the sharp radial boundary of the filament, lose coherence within 2-3 periods of wakefield oscillations, and the wake decays. The laser pulse is thus accompanied by a short-lived, almost aperiodic electron current coupled to the sharp index gradient. The comprehensive 3D hydrodynamic model shows that this structure emits a broad-band THz radiation, with the highest power emitted in the near-forward direction. The THz radiation pattern contains information on wake currents surrounding the laser pulse, thus serving as an all-optical diagnostic tool. The results are tested in cylindrical and full 3D PIC simulations using codes WAKE and EPOCH.

  8. High power diode laser vaporization of the prostate: preliminary results for benign prostatic hyperplasia. (United States)

    Erol, Ali; Cam, Kamil; Tekin, Ali; Memik, Omur; Coban, Soner; Ozer, Yavuz


    Vaporization techniques using lasers have gained wide acceptance for benign prostatic hyperplasia as an alternative to transurethral prostate resection. The high power, 980 nm wavelength diode laser is a new promising alternative with a more rapid ablation rate and excellent hemostatic properties, as shown in ex vivo and in vivo animal models. We prospectively evaluated vaporization efficiency of the high power, 980 nm diode laser for bladder outlet obstruction due to benign prostatic hyperplasia. A total of 47 consecutive patients were included in the study. Inclusion criteria were maximal flow rate 12 ml per second or less with voided volume 150 ml or greater, International Prostate Symptom Score 12 or greater and quality of life score 3 or greater. Patients with a history of neurogenic voiding dysfunction, chronic prostatitis, or prostate or bladder cancer were excluded from analysis. Preoperative maximal flow rate, post-void residual urine, International Prostate Symptom Score, quality of life, International Index of Erectile Function-5, prostate specific antigen and prostate volume were compared with values at 3 and 6 months. Complications were assessed. Month 3 assessment revealed that the mean +/- SD International Prostate Symptom Score decreased significantly from 21.93 +/- 4.88 to 10.31 +/- 3.79 (p = 0.0001). The mean maximal flow rate increased significantly from 8.87 +/- 2.18 to 17.51 +/- 4.09 ml per second (p = 0.0001). Quality of life score changed considerably compared to baseline. All of these values showed slight improvement at month 6. There was no deterioration in erectile function according to the International Index of Erectile Function-5 short form. Post-void residual urine decreased significantly. Prostate volume and prostate specific antigen reductions were also significant. The most common postoperative complications were retrograde ejaculation (13 of 41 patients or 31.7%) and irritative symptoms (11 of 47 or 23.4%), which subsided in the

  9. The research progress of large-aperture fused silica for high power laser (United States)

    Shao, Zhufeng; Wang, Yufen; Xiang, Zaikui; Rao, Chuandong


    Because of its excellent optical performance, the fused silica is widely used in laser industry. In addition, the fused silica can withstand high power laser, due to its pure component, and the performance is most outstanding within all types of glasses. So fused silica can be used for optical lens in high power laser field. From the manufacturing process stand point, the fused silica can be categorized to four types: type Ⅰ, type Ⅱ, type Ⅲ, and type Ⅳ. The fused silica of type Ⅰand type Ⅱ is made through melting silica sand in graphite furnace or oxyhydrogen flame. There are many defects in these types of fused silica, for example, the air bubbles, inclusions and metallic impurity. The other two types are made by synthetic reaction of SiCl4 with water in oxyhydrogen or plasma flame. Both type Ⅲ and Ⅳ have excellent performance in transmittance and internal quality. However, type Ⅳof fused silica has disadvantage in small aperture and overall high manufacturing cost. Take the transmittance and internal quality into consideration, the type Ⅲ fused silica is the most suitable for large-aperture lens, and can withstand high power laser. The systemic studies of manufacturing process were done to improve the performance of type Ⅲ fused silica in various areas, for instance, the optical homogeneity, the stress birefringence, the absorption coefficient and the damage threshold. There are four steps in manufacturing process of type Ⅲ fused silica, ingot production, reshaping, annealing and cold-working. The critical factors of ingot production, like the flame of burner and the structure of furnace, were deeply studied in this paper to improve the performance of fused silica. On the basis of the above research, the performance and quality of the fused silica measured up to advanced world levels. For instance, the result of optical homogeneity can be controlled to 2~5 ppm, the stress birefringence is better than 4 nm/cm, the absorption coefficient

  10. Seeing laser scalpel: a novel monolithic high-power diode pumped Tm:YAG laser system at 2.02 μm with double-clad fiber combined OCT (United States)

    Messner, Manuel; Heinrich, Arne; Hagen, Clemens; Unterrainer, Karl


    We report on a novel monolithic high-power diode pumped Tm:YAG laser at 2.02 μm. The pulsed laser generates average output power and pulse energy of beyond 90W and 900mJ in 400 μs pulses, respectively. This wavelength allows usage of standard fused silica fibers and optics, a price competitive solution for minimally-invasive endoscopic surgery. Recent developments in double-clad fiber combiners enable a rugged delivery system for the laser and the OCT ideal for a seeing laser scalpel. This gives the possibility to detect in-depth underlying tissue not yet ablated by the laser in a 2D or 3D fashion with micrometer resolution.

  11. High-power diode-pumped solid-state lasers for optical space communications (United States)

    Koechner, Walter; Burnham, Ralph; Kasinski, Jeff; Bournes, Pat; Dibiase, Don; Le, Khoa; Marshall, Larry; Hays, Alan


    The design and performance of a large diode-pumped multi-stage Nd:YAG laser system for space and airborne applications will be described. The laser operates at a repetition rate of 40 Hz and produces an output either at 1.064 micron or 532 nm with an average power in the Q-switched mode of 30 W at the fundamental and 20 W at the second harmonic wavelength. The output beam is diffraction limited (TEM 00 mode) and can optionally also be operated in a single longitudinal mode. The output energy ranges from 1.25 Joule/pulse in the free lasing mode, 0.75 Joule in a 17 nsec Q-switched pulse, to 0.5 Joules/pulse at 532 nm. The overall electrical efficiency for the Q-switched second harmonic output is 4.

  12. New generation high-power rare-earth-doped phosphate glass fiber and fiber laser (United States)

    Wu, Ruikun; Myers, John D.; Myers, Michael J.


    High power, high brightness fiber lasers have numerous potential commercial and military applications. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. Kigre has invented a new family of Er/Yb/Nd phosphate laser glass materials (designated QX) that promise to facilitate a quantum leap in fiber laser technology of this field. The new phosphate glass Rare-Earth doped fiber exhibit many advantages than Silica or Fluoride base fiber, see table.1. Instead of 30 to 50 meters of fused silica with a 50 mm bend radii; Kigre's phosphate glass fiber amplifiers may be designed to be less than 4 meters long .Laser performance and various design parameters, such as the fiber core diameter, NA, inner cladding shape and doping concentration are evaluated. Laser performances was demonstrated for an experimental QX/Er doubled clading fiber commissioned by MIT having 8 micron core, a 240 X 300 micron rectangle shaped inner cladding with 0.4 NA and 500 micron outer clading.. Kigre obtained approximately 2 dB/cm gain from 15cm long fiber under 940nm pumping The same fiber was evaluated by researcher at MIT. They used 975nm pump source. Maximum 270mW output was demonstrated by 30 cm long fiber with Fresnel reflection resonator mirrors. The slope efficiency of absorbed pump power s 47%.

  13. Heavy-section welding with very high power laser beams: the challenge (United States)

    Goussain, Jean-Claude; Becker, Ahim; Chehaibou, A.; Leca, P.


    The 45 kW CO2 laser system of Institut de Soudure was used to evaluate and explore the possibilities offered by the high power laser beams for welding different materials in various thickness and in different welding positions. Stainless steels, low carbon steels, aluminum and titanium alloys were studied. Butt joints in 10 to 35 mm thick plates were achieved and evaluated by radiographic, metallurgical and mechanical tests. Gaps and alignment tolerances were determined with and without filler wire in order to obtain acceptable welds concerning the weld geometry, the aspect on front and end root sides. The main problem raised by heavy section welding concerns weld porosity in the weld which increases drastically with the thickness of the weld. Indications are given on their origin and the way to proceed in order to better control them. Lastly some large parts, recently welded on the system, are presented and discussed before drawing some conclusions on the prospects of very high power laser welding.

  14. Thermal and laser properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ for high power dual-wavelength laser. (United States)

    Wu, K; Hao, L Z; Yu, H H; Wang, Z P; Wang, J Y; Zhang, H J


    We measured the thermal properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ (Nd:LuSGG) crystal, including the thermal expansion coefficient, specific heat, and thermal diffusion coefficient. The calculated thermal conductivity is 4.4 W/mK at room temperature. A high-power continuous-wave and passively Q-switched Nd:LuSGG laser was also demonstrated. Continuous-wave output power of 6.96 W is obtained which is the highest power with this material. For the first time to our knowledge, the passively Q-switched Nd:LuSGG laser is reported with the shortest pulse width, largest pulse energy, and highest peak power are achieved to be 5.1 ns, 62.5 μJ, and 12 kW, respectively. By spectral analysis, it has been found that the Nd:LuSGG laser was located at 1059 nm under low pump power, and became dual-wavelength at 1061.5 and 1059 nm when the incident pump power is over 2.27 W. The generating mechanism of dual-wavelength laser is also discussed.

  15. High-power diode-end-pumped Tm:YLF slab laser delivering 189 W at 1890 nm

    CSIR Research Space (South Africa)

    Koen, W


    Full Text Available The authors present a high-power Tm:YLF slab laser double-end-pumped by two 300 W laser diode stacks. The resonator was designed such that the laser emitted at 1890 nm instead of the conventional operating wavelength of 1912 nm. At full incident...

  16. Efficient generation of 3.5W laser light at 515nm by frequency doubling a single-frequency high power DBR tapered diode laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Müller, André


    More than 3.5 W of green light at 515 nm is generated by frequency doubling a single-frequency high power DBR tapered diode laser. The frequency doubling is performed in a cascade of PPMgLN and PPMgSLT crystals in order to reach high power and avoid thermal effects present in PPMgLN at high power...

  17. Reflective Optical Chopper Used in NIST High-Power Laser Measurements

    Directory of Open Access Journals (Sweden)

    Cromer, Chris


    Full Text Available For the past ten years, NIST has used high-reflectivity, optical choppers as beamsplitters and attenuators when calibrating the absolute responsivity and response linearity of detectors used with high-power CW lasers. The chopper-based technique has several advantages over the use of wedge-shaped transparent materials (usually crystals often used as beam splitters in this type of measurement system. We describe the design, operation and calibration of these choppers. A comparison between choppers and transparent wedge beampslitters is also discussed.

  18. Method and apparatus for reducing coherence of high-power laser beams (United States)

    Moncur, Norman K.; Mayer, Frederick J.


    Method and apparatus for reducing the coherence and for smoothing the power density profile of a collimated high-power laser beam in which the beam is focused at a point on the surface of a target fabricated of material having a low atomic number. The initial portion of the focused beam heats the material to form a hot reflective plasma at the material surface. The remaining, major portion of the focused beam is reflected by the plasma and recollected to form a collimated beam having reduced beam coherence.

  19. Photoconductive Semiconductor Switch Technology for Short Pulse Electromagnetics and Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Denison, Gary J.; Helgeson, Wesley D.; Hjalmarson, Harold P.; Loubriel, Guillermo M.; Mar, Alan; O' Malley, Martin W.; Zutavern, Fred J.


    High gain photoconductive semiconductor switches (PCSS) are being used to produce high power electromagnetic pulses foc (1) compact, repetitive accelerators, (2) ultra-wide band impulse sources, (3) precision gas switch triggers, (4) optically-activated firesets, and (5) high power optical pulse generation and control. High power, sub-nanosecond optical pulses are used for active optical sensors such as compact optical radars and range-gated hallistic imaging systems. Following a brief introduction to high gain PCSS and its general applications, this paper will focus on PCSS for optical pulse generation and control. PCSS technology can be employed in three distinct approaches to optical pulse generation and control: (1) short pulse carrier injection to induce gain-switching in semiconductor lasers, (2) electro-optical Q-switching, and (3) optically activated Q-switching. The most significant PCSS issues for these applications are switch rise time, jitter, and longevity. This paper will describe both the requirements of these applications and the most recent results from PCSS technology. Experiments to understand and expand the limitations of high gain PCSS will also be described.

  20. Parametric Study and Multi-Criteria Optimization in Laser Cladding by a High Power Direct Diode Laser (United States)

    Farahmand, Parisa; Kovacevic, Radovan


    In laser cladding, the performance of the deposited layers subjected to severe working conditions (e.g., wear and high temperature conditions) depends on the mechanical properties, the metallurgical bond to the substrate, and the percentage of dilution. The clad geometry and mechanical characteristics of the deposited layer are influenced greatly by the type of laser used as a heat source and process parameters used. Nowadays, the quality of fabricated coating by laser cladding and the efficiency of this process has improved thanks to the development of high-power diode lasers, with power up to 10 kW. In this study, the laser cladding by a high power direct diode laser (HPDDL) as a new heat source in laser cladding was investigated in detail. The high alloy tool steel material (AISI H13) as feedstock was deposited on mild steel (ASTM A36) by a HPDDL up to 8kW laser and with new design lateral feeding nozzle. The influences of the main process parameters (laser power, powder flow rate, and scanning speed) on the clad-bead geometry (specifically layer height and depth of the heat affected zone), and clad microhardness were studied. Multiple regression analysis was used to develop the analytical models for desired output properties according to input process parameters. The Analysis of Variance was applied to check the accuracy of the developed models. The response surface methodology (RSM) and desirability function were used for multi-criteria optimization of the cladding process. In order to investigate the effect of process parameters on the molten pool evolution, in-situ monitoring was utilized. Finally, the validation results for optimized process conditions show the predicted results were in a good agreement with measured values. The multi-criteria optimization makes it possible to acquire an efficient process for a combination of clad geometrical and mechanical characteristics control.

  1. High-power Tm-doped fiber distributed-feedback laser at 1943 nm. (United States)

    Zhang, Z; Shen, D Y; Boyland, A J; Sahu, J K; Clarkson, W A; Ibsen, M


    We report on high-power operation of a fiber distributed-feedback (DFB) laser fabricated from Tm-doped photosensitive alumino-silicate fiber and in-band pumped by an Er/Yb fiber laser at 1565 nm. The fiber DFB laser yielded up to 875 mW of single-ended output at 1943 nm on two orthogonally polarized modes for 3.5 W of absorbed pump power. Further scaling of the DFB laser output power was achieved with the aid of a simple Tm-doped fiber amplifier stage spliced directly to the DFB fiber without the need of an optical isolator. The maximum output power from the DFB laser and fiber amplifier was >3 W for a combined absorbed pump power of 8.1 W. The influence of thermal loading, owing to quantum defect heating in the Tm-doped core, on the output power and longitudinal mode behavior is discussed, and the prospects for further improvement in performance are considered.

  2. High Power Laser Diode Array Qualification and Guidelines for Space Flight Environments (United States)

    Ott, Melanie N.; Eegholm, Niels; Stephen, Mark; Leidecker, Henning; Plante, Jeannette; Meadows, Byron; Amzajerdian, Farzin; Jamison, Tracee; LaRocca, Frank


    High-power laser diode arrays (LDAs) are used for a variety of space-based remote sensor laser programs as an energy source for diode-pumped solid-state lasers. LDAs have been flown on NASA missions including MOLA, GLAS and MLA and have continued to be viewed as an important part of the laser-based instrument component suite. There are currently no military or NASA-grade, -specified, or - qualified LDAs available for "off-the-shelf" use by NASA programs. There has also been no prior attempt to define a standard screening and qualification test flow for LDAs for space applications. Initial reliability studies have also produced good results from an optical performance and stability standpoint. Usage experience has shown, howeve that the current designs being offered may be susceptible to catastrophic failures due to their physical construction (packaging) combined with the electro-optical operational modes and the environmental factors of space application. design combined with operational mode was at the root of the failures which have greatly reduced the functionality of the GLAS instrument. The continued need for LDAs for laser-based science instruments and past catastrophic failures of this part type demand examination of LDAs in a manner which enables NASA to select, buy, validate and apply them in a manner which poses as little risk to the success of the mission as possible.

  3. Influence of the ion mass on quantum electrodynamics processes with the next generation high power lasers (United States)

    Capdessus, Remi; McKenna, Paul; Strathclyde Intense Laser Interactions Studies Group Team


    The construction of a number of new multi-petawatt laser facilities in Europe, USA and China has generated intense interest in the exploration of new physical regimes involving ultra-strong electromagnetic fields in which a significant amount of the laser energy is converted into high energy synchrotron radiation and in which electron-positron pairs can be produced. These new laser facilities will enable experimental exploration of this science for the first time. From an ultra-intense laser pulse (I > 1023 W/cm2) interacting with a plasma, we bring out the impact of the ion collective dynamics on the basic quantum electrodynamics processes such as high energy synchrotron radiation generation and the production of electron-positron pairs in the non-linear Breit-Wheeler process. Relevant cases are qualitatively discussed as well as potential future experiments. This work is supported by EPSRC (Grant No. EP/P007082/1).

  4. Removal of graffiti from quarry stone by high power diode laser (United States)

    Penide, J.; Quintero, F.; Riveiro, A.; Sánchez-Castillo, A.; Comesaña, R.; del Val, J.; Lusquiños, F.; Pou, J.


    The integrity of architectural monuments in urban areas is threatened by numerous attacks, among which the graffiti is sometimes one of the most important. Particularly, Morelia's historic center (Mexico) (appointed World Heritage Site by UNESCO) suffers, for some years, a high number of graffiti. Most of these monuments in Morelia were built using a local stone called Pink Morelia Quarry. In this paper, we present the results of a study on the feasibility to remove the graffiti from Pink Morelia Quarry using a high power diode laser treatment. An extensive experimental analysis of the operating conditions has been carried out leading to successful results. The optimal parameters to achieve a total removal of graffiti have been determined. We concluded that continuous wave regime leads to better results than modulated wave regime, additionally, a two laser passes process demonstrated a high performance.

  5. Scanning high-power continuous wave laser-generated bulk acoustic waves. (United States)

    Li, Zheng; Yan, Shiling; Xie, Qingnan; Ni, Chenyin; Shen, Zhonghua


    The ultrasonic bulk waves generated by a high-power continuous laser scanning along the surface of aluminum material were theoretically investigated. Although the temperature rise generated by this scanning laser irradiation was small, it provided a large temperature gradient, which was able to generate measurable ultrasonic waves. Detailed discussions were given to the influence of scanning speed on the generation propagation direction and the amplitude of the wavefront. The longitudinal and transverse waves would be generated in the material only when the scanning speeds reached a certain range. What's more, the amplitude of the wavefronts were significantly enhanced if the wavefront angle controlled by the scanning speed matched with the propagation direction of the ultrasound. In summary, it expounded a method to obtain the ultrasonic signal of direction, controlled from the perspective of numerical simulation, as long as the scanning speed met the requirements.

  6. High-Power 1180-nm GaInNAs DBR Laser Diodes

    DEFF Research Database (Denmark)

    Aho, Antti T.; Viheriala, Jukka; Korpijarvi, Ville-Markus


    We report high-power 1180-nm GaInNAs distributed Bragg reflector laser diodes with and without a tapered amplifying section. The untapered and tapered components reached room temperature output powers of 655 mW and 4.04 W, respectively. The diodes exhibited narrow linewidth emission with side......-mode suppression ratios in the range of 50 dB for a broad range of operating current, extending up to 2 A for the untapered component and 10 A for the tapered component. The high output power is rendered possible by the use of a high quality GaInNAs-based quantum well gain region, which allows for lower strain...... and better carrier confinement compared with traditional GaInAs quantum wells. The development opens new opportunities for the power scaling of frequency-doubled lasers with emission at yellow-orange wavelengths....

  7. High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

    Directory of Open Access Journals (Sweden)

    Yulong Tang


    Full Text Available Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790  nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106  nm from 1949 to 2055  nm. The output power exceeds 20  W over 90-nm range and the maximum output power is 32  W at 1949  nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240  nm from 1866 to 2107  nm with the output power larger than 10  W.

  8. Ultrashort Laser Pulses in Biology and Medicine

    CERN Document Server

    Braun, Markus; Zinth, Wolfgang


    Sources of ultrashort laser pulses are nowadays commercially available and have entered many areas of research and development. This book gives an overview of biological and medical applications of these laser pulses. The briefness of these laser pulses permits the tracing of the fastest processes in photo-active bio-systems, which is one focus of the book. The other focus is applications that rely on the high peak intensity of ultrashort laser pulses. Examples covered span non-linear imaging techniques, optical tomography, and laser surgery.

  9. Spectral diagnostics of a vapor-plasma plume produced during welding titanium with a high-power ytterbium fiber laser (United States)

    Uspenskiy, S. A.; Petrovskiy, V. N.; Bykovskiy, D. P.; Mironov, V. D.; Prokopova, N. M.; Tret'yakov, E. V.


    This work is devoted to the research of welding plume during high power ytterbium fiber laser welding of a titanium alloy in the Ar shielding gas environment. High speed video observation of a vapor-plasma plume for visualization of processes occurring at laser welding was carried out. The coefficient of the inverse Bremsstrahlung absorption of laser radiation is calculated for a plasma welding plume by results of spectrometer researches. The conclusion deals with the impact of plasma on a high-power fiber laser radiation.

  10. High-power green light generation by second harmonic generation of single-frequency tapered diode lasers

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Sumpf, Bernd


    laser emits in excess of 9 W single-frequency output power with a good beam quality. The output from the tapered diode laser is frequency doubled using periodically poled MgO:LiNbO3. We investigate the modulation potential of the green light and improve the modulation depth from 1:4 to 1:50.......We demonstrate the generation of high power (>1.5W) and single-frequency green light by single-pass second harmonic generation of a high power tapered diode laser. The tapered diode laser consists of a DBR grating for wavelength selectivity, a ridge section and a tapered section. The DBR tapered...

  11. The generation of amplified spontaneous emission in high-power CPA laser systems. (United States)

    Keppler, Sebastian; Sävert, Alexander; Körner, Jörg; Hornung, Marco; Liebetrau, Hartmut; Hein, Joachim; Kaluza, Malte Christoph


    An analytical model is presented describing the temporal intensity contrast determined by amplified spontaneous emission in high-intensity laser systems which are based on the principle of chirped pulse amplification. The model describes both the generation and the amplification of the amplified spontaneous emission for each type of laser amplifier. This model is applied to different solid state laser materials which can support the amplification of pulse durations ≤350 fs . The results are compared to intensity and fluence thresholds, e.g. determined by damage thresholds of a certain target material to be used in high-intensity applications. This allows determining if additional means for contrast improvement, e.g. plasma mirrors, are required for a certain type of laser system and application. Using this model, the requirements for an optimized high-contrast front-end design are derived regarding the necessary contrast improvement and the amplified "clean" output energy for a desired focussed peak intensity. Finally, the model is compared to measurements at three different high-intensity laser systems based on Ti:Sapphire and Yb:glass. These measurements show an excellent agreement with the model.

  12. High-power Ti:sapphire lasers for spectroscopy of antiprotonic atoms and radioactive ions

    Energy Technology Data Exchange (ETDEWEB)

    Hori, M., E-mail: [Max-Planck-Institut fuer Quantenoptik (Germany); Dax, A. [University of Tokyo, Department of Physics (Japan); Soter, A. [Max-Planck-Institut fuer Quantenoptik (Germany)


    The ASACUSA collaboration has developed injection-seeded Ti:sapphire lasers of linewidth {Gamma}{sub pl} {approx} 6 MHz, pulse energy 50-100 mJ, and output wavelength {lambda} = 726-941 nm. They are being used in two-photon spectroscopy experiments of antiprotonic helium atoms at the Antiproton Decelerator (AD) of CERN. Ti:sapphire lasers of larger linewidth {Gamma}{sub pl} {approx} 100 MHz but more robust design will also be used in collinear resonance ionization spectroscopy (CRIS) experiments of neutron-deficient francium ions at the ISOLDE facility.

  13. High-power Ti:sapphire lasers for spectroscopy of antiprotonic atoms and radioactive ions (United States)

    Hori, M.; Dax, A.; Soter, A.

    The ASACUSA collaboration has developed injection-seeded Ti:sapphire lasers of linewidth Γpl ˜ 6 MHz, pulse energy 50-100 mJ, and output wavelength λ = 726-941 nm. They are being used in two-photon spectroscopy experiments of antiprotonic helium atoms at the Antiproton Decelerator (AD) of CERN. Ti:sapphire lasers of larger linewidth Γpl ˜ 100 MHz but more robust design will also be used in collinear resonance ionization spectroscopy (CRIS) experiments of neutron-deficient francium ions at the ISOLDE facility.

  14. Pulsed laser deposition: metal versus oxide ablation

    NARCIS (Netherlands)

    Doeswijk, L.M.; Rijnders, Augustinus J.H.M.; Blank, David H.A.


    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets

  15. Dash line glass- and sapphire-cutting with high power USP laser (United States)

    Mishchik, Konstantin; Chassagne, Bruno; Javaux-Léger, Clémentine; Hönninger, Clemens; Mottay, Eric; Kling, Rainer; Lopez, John


    Glass cutting is a subject of high interest for flat panel display and consumer electronics industries. Among laser-based, water jet-based and diamond tool-based existing solutions, ultra-short pulses (USP) appear as a promising technology since this laser technology has the unique capacity to produce highly localized bulk modification owing to non-linear absorption. The cutting using USP lasers could be performed either by full ablation which is slow and generates a lot of dust, by controlled fracture propagation which is slow as well and may lead to path deviation, by stealth dicing which produces rough sidewalls, or by self-breaking induced by in-volume laser irradiation. The laser treatment is often continuous which is not necessary to perform glass cutting and may lead to over-exposure. In this paper we report on single pass glass and sapphire cutting using an USP laser (20W @200kHz or 8W@2MHz) using dash line laser treatment along the cutting trajectory. In-volume energy deposition was done along the glass thickness owing to a Bessel beam. The results will be discussed in terms of sidewall profile and roughness, path deviation, rim sharpness, energy dose and feed rate. Dash line treatment enables to tune the energy deposition and to produce the cutting effect but with a narrower heat affected zone, a better sidewall quality and a more accurate trajectory control of the cutting path.

  16. [Diagnosis and analysis of high power YAG laser and MAG arc hybrid source with spectral information]. (United States)

    Li, Zhi-yong; Wang, Wei; Wang, Xu-you; Li, Huan


    High power YAG laser and MAG are hybrid source is a promising material processing heat source for future industry application Diagnosis of the plasma state is critical for better understanding of the coupling effect, application of the source and optimization of the hybrid parameters. Through establishing a hollow probe spectral collecting system, Avaspec-Ft-2 high speed digital spectrometer was applied for collecting the spectral information of hybrid are plasma. The hollow probe scans the plasma body to acquire the spatial distribution of the YAG laser-MAG hybrid are spectrum. The radiation intensity in specific spectral zone was acquired for analysis of the radiation variation when the laser beam was hybrid with the MAG arc. High speed photo was also applied for comparison of the plasma with and without laser beam coupling. Furthermore, line spectra of Fe I were selected for calculating the electronic temperature of the hybrid plasma with Boltzmann plot method. The results show that energy of the hybrid plasma focused on the weld plate with high intensity and wider acting zone. The electronic temperature increased in the center of the hybrid plasma.

  17. Generation of high-power few-cycle lasers via Brillouin-based plasma amplification (United States)

    Zhang, Z. M.; Zhang, B.; Hong, W.; Deng, Z. G.; Teng, J.; He, S. K.; Zhou, W. M.; Gu, Y. Q.


    Strong coupling stimulated Brillouin backscattering (sc-SBS) in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers. Here, we report on a new regime of brillouin-based plasma amplification, producing an amplified pulse with a duration of 5 fs and unfocused intensity of 6 × 1017 W/cm2. The results are obtained from 2D particle-in-cell simulations, using two circularly polarized pump and seed pulse with Gaussian transverse profile, both at an intensity of 2.74 × 1016 W/cm2, counter-propagating in a 0.3nc plasma. The significant compression of amplified seed is achieved as a result of sc-SBS amplification as well as additional compression by the interplay between self-phase modulation and negative group delay dispersion. We show that the amplified seed retains high beam qualities since the filamentation can be prevented due to the fast compression. This scheme may pave the way for few-cycle laser pulses to reach exawatt or even zetawatt regime.

  18. Research of high power and stable laser in portable Raman spectrometer based on SHINERS technology (United States)

    Cui, Yongsheng; Yin, Yu; Wu, Yulin; Ni, Xuxiang; Zhang, Xiuda; Yan, Huimin


    The intensity of Raman light is very weak, which is only from 10-12 to 10-6 of the incident light. In order to obtain the required sensitivity, the traditional Raman spectrometer tends to be heavy weight and large volume, so it is often used as indoor test device. Based on the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) method, Raman optical spectrum signal can be enhanced significantly and the portable Raman spectrometer combined with SHINERS method will be widely used in various fields. The laser source must be stable enough and able to output monochromatic narrow band laser with stable power in the portable Raman spectrometer based on the SHINERS method. When the laser is working, the change of temperature can induce wavelength drift, thus the power stability of excitation light will be affected, so we need to strictly control the working temperature of the laser, In order to ensure the stability of laser power and output current, this paper adopts the WLD3343 laser constant current driver chip of Wavelength Electronics company and MCU P89LPC935 to drive LML - 785.0 BF - XX laser diode(LD). Using this scheme, the Raman spectrometer can be small in size and the drive current can be constant. At the same time, we can achieve functions such as slow start, over-current protection, over-voltage protection, etc. Continuous adjustable output can be realized under control, and the requirement of high power output can be satisfied. Max1968 chip is adopted to realize the accurate control of the laser's temperature. In this way, it can meet the demand of miniaturization. In term of temperature control, integral truncation effect of traditional PID algorithm is big, which is easy to cause static difference. Each output of incremental PID algorithm has nothing to do with the current position, and we can control the output coefficients to avoid full dose output and immoderate adjustment, then the speed of balance will be improved observably. Variable

  19. High power, widely tunable dual-wavelength 2 μm laser based on intracavity KTP optical parametric oscillator (United States)

    Yan, Dexian; Wang, Yuye; Xu, Degang; Shi, Wei; Zhong, Kai; Liu, Pengxiang; Yan, Chao; Mei, Jialin; Shi, Jia; Yao, Jianquan


    We presented a high power, widely tunable narrowband 2 μm dual-wavelength source employing intracavity optical parametric oscillator with potassium titanium oxide phosphate (KTP) crystal. Two identical KTP crystals were oriented oppositely in the OPO cavity to compensate the walk-off effect. The output average power of dual-wavelength 2 μm laser was up to 18.18 W at 10 kHz with the peak power of 165 kW. The two wavelengths can be tuned in the range of 2070.7 nm to 2191.1 nm for ordinary light while in the range of 2190.7 nm to 2065.9 nm for extraordinary light with the full width at half maximum (FWHM) about 0.8 nm. The pulse width of the tunable laser was as narrow as 11 ns. The beam quality factor M 2 was less than 4 during wavelength tuning.

  20. Efficient, High-Power Mid-Infrared Laser for National Securityand Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kiani, Leily S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    The LLNL fiber laser group developed a unique short-wave-infrared, high-pulse energy, highaverage- power fiber based laser. This unique laser source has been used in combination with a nonlinear frequency converter to generate wavelengths, useful for remote sensing and other applications in the mid-wave infrared (MWIR). Sources with high average power and high efficiency in this MWIR wavelength region are not yet available with the size, weight, and power requirements or energy efficiency necessary for future deployment. The LLNL developed Fiber Laser Pulsed Source (FiLPS) design was adapted to Erbium doped silica fibers for 1.55 μm pumping of Cadmium Silicon Phosphide (CSP). We have demonstrated, for the first time optical parametric amplification of 2.4 μm light via difference frequency generation using CSP with an Erbium doped fiber source. In addition, for efficiency comparison purposes, we also demonstrated direct optical parametric generation (OPG) as well as optical parametric oscillation (OPO).

  1. Comparison Between NIST and AF Laser Energy Standards Using High Power Lasers. (United States)

    Li, Xiaoyu; Scott Retired, Thomas; Cromer, Chris; Cooper, David; Comisford, Steven


    We report the results of a high-energy laser calorimeter comparison conducted by the National Institute of Standards and Technology (NIST), Boulder, Colorado and the U.S. Air Force Primary Standards laboratory (AFPSL), Heath, Ohio. A laser power meter, used as a transfer standard, was calibrated at each laboratory, sequentially, and the measurement results were compared. These measurements were performed at a nominal power of 800 W and a wavelength of 10.6 μm using CO2 lasers. Excellent measurement agreement (1.02 %) was demonstrated, which was well within each of the expanded uncertainties from the two laboratories involved in this comparison.

  2. Pulsed Laser Spectroscopy: An Inexpensive Approach (United States)

    Daly, J. G.; Hastings, R.; Schmidt, J. A.


    The assembly of a pulsed laser spectroscopy laboratory is presented. The authors describe how they constructed pulsed lasers, fast photodetectors, a boxcar signal averager, and associated equipment. A molecular nitrogen laser operating up to 50 Hz with an ultraviolet (337.1 nm) 700 kW pulse was used to optically pump an organic dye laser. The resulting output could be tuned from 360.0 to 680.0 nm. This pulse was typically 30 kW and 8 nsec, which makes it ideally suited to selective excitation and fluorescence studies. By constructing this equipment, it is estimated that the investment was one-tenth the cost of commercial components.

  3. Numerical simulation of the power characteristics of twin-core pulse reactor-pumped laser system (United States)

    Gulevich, A. V.; Barzilov, A. P.; Dyachenko, P. P.; Zrodnikov, A. V.; Kukharchuk, O. F.; Kachanov, B. V.; Kolyada, S. G.; Pashin, E. A.


    Concept for high-power pulsed reactor-pumped laser system (RPLS) based on the new physical principles (direct nuclear-to-optical conversion) is discussed with reference to ICF feasibility problem. Theoretical problems for substantiation of the neutronic and physical characteristics of the RPLS power model are considered. Results of numerical studies of the expected power characteristics of reactor laser system are discussed.

  4. Monolithic micro-laser with KTP ridge waveguides for injection seeding high power lasers Project (United States)

    National Aeronautics and Space Administration — This NASA Small Business Innovation Research Phase I project will develop a technique to greatly improve the direct coupling of a diode laser to an optical waveguide...

  5. High repetition rate multi-channel source of high-power rf-modulated pulses (United States)

    Ulmaskulov, M. R.; Pedos, M. S.; Rukin, S. N.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Yalandin, M. I.; Romanchenko, I. V.; Rostov, V. V.


    This paper presents the results of testing a high voltage pulse generator based on parallel gyromagnetic nonlinear transmission lines filled with saturable ferrite. The generator is capable of producing almost identical stable rf-modulated nanosecond high voltage pulses in each of the two, or four, parallel output channels. The output voltage amplitude in each channel can reach -285 or -180 kV, respectively, with a rf modulation depth of up to 60%. Drive pulses were produced as the packets of duration 1-5 s at a pulse repetition frequency of 800 Hz using a driver equipped with all-solid-state switches. Splitting the driver pulse provided electric field strengths in the channels which were below the breakdown field strength of the transmission lines. As a result, the use of nonlinear transmission lines of reduced diameter made it possible to increase the center frequency of the excited rf oscillations to ˜2 GHz.

  6. High repetition rate multi-channel source of high-power rf-modulated pulses. (United States)

    Ulmaskulov, M R; Pedos, M S; Rukin, S N; Sharypov, K A; Shpak, V G; Shunailov, S A; Yalandin, M I; Romanchenko, I V; Rostov, V V


    This paper presents the results of testing a high voltage pulse generator based on parallel gyromagnetic nonlinear transmission lines filled with saturable ferrite. The generator is capable of producing almost identical stable rf-modulated nanosecond high voltage pulses in each of the two, or four, parallel output channels. The output voltage amplitude in each channel can reach -285 or -180 kV, respectively, with a rf modulation depth of up to 60%. Drive pulses were produced as the packets of duration 1-5 s at a pulse repetition frequency of 800 Hz using a driver equipped with all-solid-state switches. Splitting the driver pulse provided electric field strengths in the channels which were below the breakdown field strength of the transmission lines. As a result, the use of nonlinear transmission lines of reduced diameter made it possible to increase the center frequency of the excited rf oscillations to ∼2 GHz.

  7. New generation all-silica based optical elements for high power laser systems (United States)

    Tolenis, T.; GrinevičiÅ«tÄ--, L.; Melninkaitis, A.; Selskis, A.; Buzelis, R.; MažulÄ--, L.; Drazdys, R.


    Laser resistance of optical elements is one of the major topics in photonics. Various routes have been taken to improve optical coatings, including, but not limited by, materials engineering and optimisation of electric field distribution in multilayers. During the decades of research, it was found, that high band-gap materials, such as silica, are highly resistant to laser light. Unfortunately, only the production of anti-reflection coatings of all-silica materials are presented to this day. A novel route will be presented in materials engineering, capable to manufacture high reflection optical elements using only SiO2 material and GLancing Angle Deposition (GLAD) method. The technique involves the deposition of columnar structure and tailoring the refractive index of silica material throughout the coating thickness. A numerous analysis indicate the superior properties of GLAD coatings when compared with standard methods for Bragg mirrors production. Several groups of optical components are presented including anti-reflection coatings and Bragg mirrors. Structural and optical characterisation of the method have been performed and compared with standard methods. All researches indicate the possibility of new generation coatings for high power laser systems.

  8. Toward realizing high power semiconductor terahertz laser sources at room temperature (United States)

    Razeghi, Manijeh


    The terahertz (THz) spectral range offers promising applications in science, industry, and military. THz penetration through nonconductors (fabrics, wood, plastic) enables a more efficient way of performing security checks (for example at airports), as illegal drugs and explosives could be detected. Being a non-ionizing radiation, THz radiation is environment-friendly enabling a safer analysis environment than conventional X-ray based techniques. However, the lack of a compact room temperature THz laser source greatly hinders mass deployment of THz systems in security check points and medical centers. In the past decade, tremendous development has been made in GaAs/AlGaAs based THz Quantum Cascade Laser (QCLs), with maximum operating temperatures close to 200 K (without magnetic field). However, higher temperature operation is severely limited by a small LO-phonon energy (~ 36 meV) in this material system. With a much larger LO-phonon energy of ~ 90 meV, III-Nitrides are promising candidates for room temperature THz lasers. However, realizing high quality material for GaN-based intersubband devices presents a significant challenge. Advances with this approach will be presented. Alternatively, recent demonstration of InP based mid-infrared QCLs with extremely high peak power of 120 W at room temperature opens up the possibility of producing high power THz emission with difference frequency generation through two mid-infrared wavelengths.

  9. High-power laser shock-induced dynamic fracture of aluminum and microscopic observation of samples

    Directory of Open Access Journals (Sweden)

    Fan Zhang


    Full Text Available High-power laser induced shocks generated by “ShenGuang II” laser facility has been used to study spall fracture of polycrystalline aluminum at strain rates more than 106/s. The free surface velocity histories of shock-loaded samples, 150 μm thick and with initial temperature from 293 K to 873 K, have been recorded using velocity interferometer system for any reflector (VISAR. From the free surface velocity profile, spall strength and yield stress are calculated, it demonstrates that spall strength will decline and yield strength increase with initial temperature. The loaded samples are recovered to obtain samples' section and free surface metallographic pictures through Laser Scanning Confocal Microscopy. It is found that there are more micro-voids and more opportunity to appear bigger voids near the spall plane and the grain size increases with temperature slowly but smoothly except the sharply change at 893 K (near melting point. Besides, the fracture mechanisms change from mainly intergranular fracture to transgranular fracture with the increase of initial temperature.

  10. Geometry modeling of single track cladding deposited by high power diode laser with rectangular beam spot (United States)

    Liu, Huaming; Qin, Xunpeng; Huang, Song; Hu, Zeqi; Ni, Mao


    This paper presents an investigation on the relationship between the process parameters and geometrical characteristics of the sectional profile for the single track cladding (STC) deposited by High Power Diode Laser (HPDL) with rectangle beam spot (RBS). To obtain the geometry parameters, namely cladding width Wc and height Hc of the sectional profile, a full factorial design (FFD) of experiment was used to conduct the experiments with a total of 27. The pre-placed powder technique has been employed during laser cladding. The influence of the process parameters including laser power, powder thickness and scanning speed on the Wc and Hc was analyzed in detail. A nonlinear fitting model was used to fit the relationship between the process parameters and geometry parameters. And a circular arc was adopted to describe the geometry profile of the cross-section of STC. The above models were confirmed by all the experiments. The results indicated that the geometrical characteristics of the sectional profile of STC can be described as the circular arc, and the other geometry parameters of the sectional profile can be calculated only using Wc and Hc. Meanwhile, the Wc and Hc can be predicted through the process parameters.

  11. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)


    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  12. Research of new packaging and cooling technique for high power fiber laser used pump coupler (United States)

    Mu, Wei; Si, Xu; Lin, Ya-jun; Xu, Cheng-lin; Ma, Yun-liang; Xiao, Chun


    This article analyzes the advantages and disadvantages of a packaging structure for pump coupler, where common heat conduction material is used. In this study, the possibility of using new technology of thermal conductivity is discussed. We also proposes a solution that make the function and effect of package more uniform. A serial of experiments are done for research the cooling effect and the working reliability of the fiber combiners and couplers. Experiment proves that after improved method of package, the cooling speed increases significantly comparing the sample with old type of package technique. The technique discussed in this paper will make the high power fiber laser working long time with steady power output and high efficiency.

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

    Directory of Open Access Journals (Sweden)

    D. H. Wu


    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.

  14. High-Power DFB Diode Laser-Based CO-QEPAS Sensor: Optimization and Performance

    Directory of Open Access Journals (Sweden)

    Yufei Ma


    Full Text Available A highly sensitive carbon monoxide (CO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS was demonstrated. A high-power distributed feedback (DFB, continuous wave (CW 2.33 μm diode laser with an 8.8 mW output power was used as the QEPAS excitation source. By optimizing the modulation depth and adding an optimum micro-resonator, compared to a bare quartz tuning fork (QTF, a 10-fold enhancement of the CO-QEPAS signal amplitude was achieved. When water vapor acting as a vibrational transfer catalyst was added to the target gas, the signal was further increased by a factor of ~7. A minimum detection limit (MDL of 11.2 ppm and a calculated normalized noise equivalent absorption (NNEA coefficient of 1.8 × 10−5 cm−1W/√Hz were obtained for the reported CO-QEPAS sensor.

  15. High-Power DFB Diode Laser-Based CO-QEPAS Sensor: Optimization and Performance. (United States)

    Ma, Yufei; Tong, Yao; He, Ying; Yu, Xin; Tittel, Frank K


    A highly sensitive carbon monoxide (CO) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was demonstrated. A high-power distributed feedback (DFB), continuous wave (CW) 2.33 μm diode laser with an 8.8 mW output power was used as the QEPAS excitation source. By optimizing the modulation depth and adding an optimum micro-resonator, compared to a bare quartz tuning fork (QTF), a 10-fold enhancement of the CO-QEPAS signal amplitude was achieved. When water vapor acting as a vibrational transfer catalyst was added to the target gas, the signal was further increased by a factor of ~7. A minimum detection limit (MDL) of 11.2 ppm and a calculated normalized noise equivalent absorption (NNEA) coefficient of 1.8 × 10-5 cm-1W/√Hz were obtained for the reported CO-QEPAS sensor.

  16. Proton acceleration experiments and warm dense matter research using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Roth, M; Alber, I; Guenther, M; Harres, K [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Bagnoud, V [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Brown, C R D [Plasma Physics Group, Imperial College London, SW7 2BZ (United Kingdom); Clarke, R; Heathcote, R; Li, B [STFC, Rutherford Appleton Laboratory (RAL), Chilton, Didcot, OX14 OQX (United Kingdom); Daido, H [Photo Medical Research Center, JAEA, Kizugawa-City, Kyoto 619-0215 (Japan); Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C [Los Alamos National Laboratory (LANL), Los Alamos, NM 87545 (United States); Geissel, M [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Glenzer, S; Kritcher, A; Kugland, N; LePape, S [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Gregori, G, E-mail: markus.roth@physik.tu-darmstadt.d [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)


    The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. In this paper we report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore, we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by x-ray Thomson scattering to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

  17. CO2 laser-fabricated cladding light strippers for high-power fiber lasers and amplifiers. (United States)

    Boyd, Keiron; Simakov, Nikita; Hemming, Alexander; Daniel, Jae; Swain, Robert; Mies, Eric; Rees, Simon; Andrew Clarkson, W; Haub, John


    We present and characterize a simple CO2 laser processing technique for the fabrication of compact all-glass optical fiber cladding light strippers. We investigate the cladding light loss as a function of radiation angle of incidence and demonstrate devices in a 400 μm diameter fiber with cladding losses of greater than 20 dB for a 7 cm device length. The core losses are also measured giving a loss of laser diode with minimal heating of the fiber coating and packaging adhesives.

  18. A broadly tunable autocorrelator for ultra-short, ultra-high power infrared optical pulses

    Energy Technology Data Exchange (ETDEWEB)

    Szarmes, E.B.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)


    We describe the design of a crossed-beam, optical autocorrelator that uses an uncoated, birefringent beamsplitter to split a linearly polarized incident pulse into two orthogonally polarized pulses, and a Type II, SHG crystal to generate the intensity autocorrelation function. The uncoated beamsplitter accommodates extremely broad tunability while precluding any temporal distortion of ultrashort optical pulses at the dielectric interface, and the specific design provides efficient operation between 1 {mu}m and 4 {mu}m. Furthermore, the use of Type II SHG completely eliminates any single-beam doubling, so the autocorrelator can be operated at very shallow crossed-beam angles without generating a background pedestal. The autocorrelator has been constructed and installed in the Mark III laboratory at Duke University as a broadband diagnostic for ongoing compression experiments on the chirped-pulse FEL.

  19. Integrated and miniaturized endoscopic devices for use during high power infrared fiber laser surgery (United States)

    Wilson, Christopher Ryan

    The Thulium Fiber Laser (TFL) is currently being studied as a potential alternative to the conventional, solid-state Holmium:YAG laser (Ho:YAG) for the treatment of kidney stones. The TFL is an ideal candidate to replace the Ho:YAG for laser lithotripsy due to a higher absorption coefficient in water of the emitted wavelength, an ability to operate at high pulse rates, and a near single mode, Gaussian spatial beam profile. The higher absorption of the TFL wavelength by water translates to a decrease in ablation threshold by a factor of four. High pulse rate operation allows higher ablation rates than the Ho:YAG, thus decreasing operation time necessary to ablate the urinary stone. The Gaussian spatial beam profile allows the TFL to couple higher laser power into smaller optical fibers than those currently being used for Ho:YAG lithotripsy. This decrease in fiber diameter translates into a potential decrease in the size of ureteroscope working channel, higher saline irrigation rates for improved visibility and safety, and may also extend to a decrease in overall ureteroscope diameter. Furthermore, the improved spatial beam profile reduces the risk of damage to the input end of the fiber. Therefore, the trunk fiber, minus the distal fiber tip, may be preserved and re-used, resulting in significant cost savings. This thesis details rapid TFL lithotripsy at high pulse rates up to 500 Hz, both with and without the aid of a stone retrieval basket, in order to demonstrate the TFL's superior ablation rates over the Ho:YAG. Collateral damage testing of the TFL effect on the ureter wall and Nitinol stone baskets were conducted to ensure patient safety for future clinical use. Proximal fiber end damage testing was conducted to demonstrate fiber preservation, critical for permanent fiber integration. Optical fibers were fitted with fabricated hollow steel tips and integrated with stone retrieval baskets for testing. Ball tipped optical fibers were tested to maintain ablation

  20. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, N., E-mail:; Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M. [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka-shi, Ibaraki 311-0193 Japan (Japan)


    R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  1. High-power passively Q-switched Yb:YCa4O(BO3)3 laser with a GaAs crystal plate as saturable absorber. (United States)

    Chen, Xiaowen; Han, Wenjuan; Xu, Honghao; Jia, Minghui; Yu, Haohai; Zhang, Huaijin; Liu, Junhai


    We report on efficient high-power passively Q-switched operation of a Yb:YCa4O(BO3)3 laser with a GaAs crystal plate acting as the saturable absorber. An average output power of 5.7 W at 1032 nm is generated at a pulse repetition rate of 166.7 kHz when the incident pump power is 26.8 W, with a slope efficiency determined to be 24.5%. The averaged pulse energy achieved is roughly 30 μJ and is increased to about 40 μJ when the output coupling used changes from 30% to 50%, while the shortest pulse width is measured to be 153 ns.

  2. Optical design and development of a fiber coupled high-power diode laser system for laser transmission welding of plastics (United States)

    Rodríguez-Vidal, Eva; Quintana, Iban; Etxarri, Jon; Azkorbebeitia, Urko; Otaduy, Deitze; González, Francisco; Moreno, Fernando


    Laser transmission welding (LTW) of thermoplastics is a direct bonding technique already used in different industrial applications sectors such as automobiles, microfluidics, electronics, and biomedicine. LTW evolves localized heating at the interface of two pieces of plastic to be joined. One of the plastic pieces needs to be optically transparent to the laser radiation whereas the other part has to be absorbent, being that the radiation produced by high power diode lasers is a good alternative for this process. As consequence, a tailored laser system has been designed and developed to obtain high quality weld seams with weld widths between 0.7 and 1.4 mm. The developed laser system consists of two diode laser bars (50 W per bar) coupled into an optical fiber using a nonimaging solution: equalization of the beam parameter product (BPP) in the slow and fast axes by a pair of step-mirrors. The power scaling was carried out by means of a multiplexing polarization technique. The analysis of energy balance and beam quality was performed considering ray tracing simulation (ZEMAX) and experimental validation. The welding experiments were conducted on acrylonitrile/butadiene/styrene (ABS), a thermoplastic frequently used in automotive, electronics and aircraft applications, doped with two different concentrations of carbon nanotubes (0.01% and 0.05% CNTs). Quality of the weld seams on ABS was analyzed in terms of the process parameters (welding speed, laser power and clamping pressure) by visual and optical microscope inspections. Mechanical properties of weld seams were analyzed by mechanical shear tests. High quality weld seams were produced in ABS, revealing the potential of the laser developed in this work for a wide range of plastic welding applications.

  3. Injection locking in a high-power XeCl laser

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, IU.I.; Ivanov, N.G.; Kovalenko, S.E.; Losev, V.F.; Panchenko, IU.N. (Inst. Sil' notochnoi Elektroniki, Tomsk (Russian Federation))


    Experimental results are presented on injection locking in an XeCl laser with an output energy of 30-40 J and an emission pulse duration of 300 ns. The external signal was 100 ns in duration, and featured a line width of 0.2/cm and an energy of 10 mJ. When the axial region of the unstable resonator was filled with the external signal in the interval from the beginning of pumping up to the time when the threshold was achieved, 90 percent of the lasing energy belonged to the injected line. 6 refs.

  4. High power GaInAs lasers with distributed Bragg reflectors (United States)

    O'Brien, S.; Parke, R.; Welch, D. F.; Mehuys, D.; Scifres, D.


    Single-mode strained-layer lasers have been fabricated which use buried second-order gratings for distributed Bragg reflectors. The lasers contain a strained GaInAs quantum well in the active region and operate in an edge emitting fashion with CW powers in excess of 110 mW. Single longitudinal and transverse mode operation is maintained at about 971.9 nm up to 42 mW. Total power conversion efficiencies as high as 28 percent have been observed. The longitudinal and transverse mode behavior is stable under 90 percent amplitude modulation with 50 percent duty cycle pulses at 10 kHz and 10 MHz. Preliminary life-test data at 40 C also indicate room temperature lifetimes in excess of 45,000 hours.

  5. Ultrashort pulse laser technology laser sources and applications

    CERN Document Server

    Schrempel, Frank; Dausinger, Friedrich


    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.

  6. High power wavelength linearly swept mode locked fiber laser for OCT imaging. (United States)

    Liu, George Y; Mariampillai, Adrian; Standish, Beau A; Munce, Nigel R; Gu, Xijia; Vitkin, I Alex


    We report a long coherence length, high power, and wide tuning range wavelength linearly swept fiber mode-locked laser based on polygon scanning filters. An output power of 52.6 mW with 112 nm wavelength tuning range at 62.6 kHz sweeping rate has been achieved. The coherence length is long enough to enable imaging over 8.1 mm depth when the sensitivity decreases by 8.7 dB (1/e(2)). The Fourier components are still distinguishable when the ranging depth exceeds 15 mm, which corresponds to 30 mm optical path difference in air. The parameters that are critical to OCT imaging quality such as polygon filter linewidth, the laser coherence length, output power, axial resolution and the Fourier sensitivity have been investigated theoretically and experimentally. Since the wavelength is swept linearly with time, an analytical approach has been developed for transforming the interference signal from equidistant spacing in wavelength to equidistant spacing in frequency. Axial resolution of 7.9 microm in air has been achieved experimentally that approaches the theoretical limit.

  7. Research on the welding process of aluminum alloy based on high power fiber laser (United States)

    Zhang, Jian; Zhang, Wei; Pan, Xiaoming; Huang, Shanshi; Liu, Wenwen


    To research the formation and variation principle of the weld seam and molten pool for aluminum alloy high power fiber laser welding, the welding experiments for 5052 aluminum alloy were carried out. The influences of laser power, scanning velocity and protection gas on the welding process were systematically researched. The results show that with the increase of power and scanning velocity, the depth to width ratio first increases and then decreases. The ratio reaches the maximum value at 2.6 KW and 30 mm/s, respectively. When the power located at 2.6 KW to 2.8 KW or the velocity located at 25 mm/s to 30 mm/s, stable deep penetration welding can be obtained. The weld seam shows relative flat appearance and the molten pool presents typical "T shape" topography. Moreover, the protection gas also influences the appearance of the weld seam. Using the independently designed fixture, the quality of the weld seam can be well improved.

  8. Active Stabilization of the Beam Pointing of a High- Power KrF Laser System

    Directory of Open Access Journals (Sweden)

    Barna1 A.


    Full Text Available An active beam-pointing stabilization system has been developed for a high-power KrF laser system to eliminate the long-term drift of the directional change of the beam in order to have a stable focusing to a high intensity. The control of the beam direction was achieved by a motor-driven mirror activated by an electric signal obtained by monitoring the position of the focus of the output beam. Instead of large sized UV-sensitive position sensitive detectors a simple arrangement with scatter plates and photodiodes are used to measure the directionality of the beam. After the beam stabilization the long-term residual deviation of the laser shots is ~14 μrad, which is comparable to the shot-to-shot variation of the beam (~12 μrad. This deviation is small enough to keep the focal spot size in a micrometer range when tightly focusing the beam using off-axis parabolic mirrors.

  9. High-power free-electron lasers-technology and future applications (United States)

    Socol, Yehoshua


    Free-electron laser (FEL) is an all-electric, high-power, high beam-quality source of coherent radiation, tunable - unlike other laser sources - at any wavelength within wide spectral region from hard X-rays to far-IR and beyond. After the initial push in the framework of the “Star Wars” program, the FEL technology benefited from decades of R&D and scientific applications. Currently, there are clear signs that the FEL technology reached maturity, enabling real-world applications. E.g., successful and unexpectedly smooth commissioning of the world-first X-ray FEL in 2010 increased in one blow by more than an order of magnitude (40×) wavelength region available by FEL technology and thus demonstrated that the theoretical predictions just keep true in real machines. Experience of ordering turn-key electron beamlines from commercial companies is a further demonstration of the FEL technology maturity. Moreover, successful commissioning of the world-first multi-turn energy-recovery linac demonstrated feasibility of reducing FEL size, cost and power consumption by probably an order of magnitude in respect to previous configurations, opening way to applications, previously considered as non-feasible. This review takes engineer-oriented approach to discuss the FEL technology issues, keeping in mind applications in the fields of military and aerospace, next generation semiconductor lithography, photo-chemistry and isotope separation.

  10. A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source (United States)

    Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de


    A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

  11. Bulk damage and absorption in fused silica due to high-power laser applications (United States)

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.


    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  12. High Power, Pulsed, RF Generation from Nonlinear Lumped Element Transmission Lines (NLETLs) (United States)


    demand pulses of energy, with each pulse containing a burst of oscillations, and often issues such as electrical breakdown and thermal management...factor calculated for an end-tire series of 20 arbitrary antenna elements. Multiplication by the directional pattern of each element results in that of...7 I-! IDOOO L oad Candbon Resistance lohml Capeciance (pF I Inductance ml £ r*e» Components by Stage 2HU J, 10 000 "IFobT ’(oooT n

  13. One laser pulse generates two photoacoustic signals

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin


    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent, signal amplitude which is caused by the concurrent heat accumulation and ...

  14. Wavelength switchable high-power diode-side-pumped rod Tm:YAG Laser around 2µm. (United States)

    Wang, Caili; Du, Shifeng; Niu, Yanxiong; Wang, Zhichao; Zhang, Chao; Bian, Qi; Guo, Chuan; Xu, Jialin; Bo, Yong; Peng, Qinjun; Cui, Dafu; Zhang, Jingyuan; Lei, Wenqiang; Xu, Zuyan


    We report a high-power diode-side-pumped rod Tm:YAG laser operated at either 2.07 or 2.02 µm depending on the transmission of pumped output coupler. The laser yields 115W of continuous-wave output power at 2.07 µm with 5% output coupling, which is the highest output power for all solid-state 2.07 μm cw rod Tm:YAG laser reported so far. With an output coupler of 10% transmission, the center wavelength of the laser is switched to 2.02 μm with an output power of 77.1 W. This is the first observation of high-power wavelength switchable diode-side-pumped rod Tm:YAG laser around 2 µm.

  15. Femtosecond Laser Pulses Principles and Experiments

    CERN Document Server

    Rullière, Claude


    This smooth introduction for advanced undergraduates starts with the fundamentals of lasers and pulsed optics. Thus prepared, the student is introduced to short and ultrashort laser pulses, and learns how to generate, manipulate, and measure them. Spectroscopic implications are also discussed. The second edition has been completely revised and includes two new chapters on some of the most promising and fast-developing applications in ultrafast phenomena: coherent control and attosecond pulses.

  16. Dark pulse quantum dot diode laser. (United States)

    Feng, Mingming; Silverman, Kevin L; Mirin, Richard P; Cundiff, Steven T


    We describe an operating regime for passively mode-locked quantum dot diode laser where the output consists of a train of dark pulses, i.e., intensity dips on a continuous background. We show that a dark pulse train is a solution to the master equation for mode-locked lasers. Using simulations, we study stability of the dark pulses and show they are consistent with the experimental results.

  17. Corrosion resistant nickel superalloy coatings laser-clad with a 6 kW high power diode laser (HPDL) (United States)

    Tuominen, Jari; Honkanen, Mari; Hovikorpi, Jari; Vihinen, Jorma; Vuoristo, Petri; Maentylae, Tapio


    A series of exerpiments were performed to investigate the one-step laser cladding of Inconel 625 powder, injected off-axially onto Fe37 and 42CrMo4 substrates. The experiments were carried out using a 6 kW high power diode laser (HPDL) mounted to a 6 axis robot system. The rectangular shape of the delivering beam was focused to a spot size of 22 x 5 mm on the work piece. The coating samples were produced using different levels of powder feed rate (77 - 113 g/min), traveling speed (300 - 400 mm/min) and laser power (4.8 - 6 kW). Hot corrosion resistance of laser-clad Inconel 625 coatings were tested in Na2SO4 - V2O5 at 650°C for 1000 hours. Wet corrosion properties of the obtained coatings were tested in immersion tests in 3.5 wt.% NaCl solution. Diode laser power of 6 kW (808 and 940 nm) was high enough to produce 20 mm wide laser-clad tracks with a thickness of 2.5 mm in a single pass, when powder feed rate was more than 6 kg/h and traverse speed was 400 mm/min. Wet corrosion properties of laser-clad Inconel 625 coatings were found to be superior to sprayed and welded coatings. Hot corrosion resistance was even slightly better than corresponding wrought alloy. Finally, one-step HPDL cladding was demonstrated in coating of shaft for hydraulic cylinder with Inconel 625 powder. Due to high coating quality, high deposition rate and traverse speed HPDL devices are very promising for large area cladding applications.

  18. High-Power Single-Mode 2.65-micron InGaAsSb/AlInGaAsSb Diode Lasers (United States)

    Frez, Clifford F.; Briggs, Ryan M.; Forouhar, Siamak; Borgentun, Carl E.; Gupta, James


    Central to the advancement of both satellite and in-situ science are improvements in continuous-wave and pulsed infrared laser systems coupled with integrated miniaturized optics and electronics, allowing for the use of powerful, single-mode light sources aboard both satellite and unmanned aerial vehicle platforms. There is a technological gap in supplying adequate laser sources to address the mid-infrared spectral window for spectroscopic characterization of important atmospheric gases. For high-power applications between 2 to 3 micron, commercial laser technologies are unsuitable because of limitations in output power. For instance, existing InP-based laser systems developed for fiber-based telecommunications cannot be extended to wavelengths longer than 2 micron. For emission wavelengths shorter than 3 micron, intersubband devices, such as infrared quantum cascade lasers, become inefficient due to band-offset limitations. To date, successfully demonstrated singlemode GaSb-based laser diodes emitting between 2 and 3 micron have employed lossy metal Bragg gratings for distributed- feedback coupling, which limits output power due to optical absorption. By optimizing both the quantum well design and the grating fabrication process, index-coupled distributed-feedback 2.65-micron lasers capable of emitting in excess of 25 mW at room temperature have been demonstrated. Specifically, lasers at 3,777/cm (2.65 micron) have been realized to interact with strong absorption lines of HDO and other isotopologues of H2O. With minor modifications of the optical cavity and quantum well designs, lasers can be fabricated at any wavelength within the 2-to-3-micron spectral window with similar performance. At the time of this reporting, lasers with this output power and wavelength accuracy are not commercially available. Monolithic ridge-waveguide GaSb lasers were fabricated that utilize secondorder lateral Bragg gratings to generate single-mode emission from InGaAsSb/ Al

  19. Reducing, by pulse width modulation, the curing temperature of a prototype high-power LED light curing unit. (United States)

    Huang, Ta-Ko; Hung, Chun-Cheng; Tsai, Chi-Cheng


    Third-generation LEDs have high irradiance and efficiency, but the associated temperature rise is potentially hazardous to the pulp of teeth. We evaluated, during composite polymerization, the irradiance and temperature rise of a prototype high-power LED light curing unit (LCU) with optimal pulse width modulation (PWM), and then compared the results with four off-the-shelf high-power LCUs. A cavity was prepared in a tooth, and a composite resin layer was applied and cured. For each LCU, the irradiance and temperature changes at the pulp-dentin junction were measured. Microhardness (Vickers hardness) of cured composite samples was measured for each LCU. Our prototype had a final temperature of 36.4 +/- 1.3 degrees C and irradiance of 1,182 +/- 1 mW/cm2. The unit with the highest temperature had a temperature of 48.7 +/- 1.2 degrees C and an irradiance of 1,194 +/- 1 mW/cm2. Based on the results of the present study, it was shown that PWM technology reduced the curing temperature while retaining the polymerization effectiveness of a high-power LED LCU.

  20. Femtosecond laser pulses principles and experiments

    CERN Document Server


    This smooth introduction for advanced undergraduate students starts with the fundamentals of lasers and pulsed optics Thus prepared, the student learns how to generate short and ultrashort laser pulses, how to manipulate them, and how to measure them Finally, spectroscopic implications are discussed This rounded text gives the student an up-to-date introduction to one of the most exciting fields in laser physics

  1. 25 years of pulsed laser deposition (United States)

    Lorenz, Michael; Ramachandra Rao, M. S.


    decade, large-area PLD grown YBa2Cu3O7-δ thin films became a reality for applications in microwave filters for satellite and mobile communication. The material systems that could be covered under the PLD gamut extended to almost all oxides, nitrides and even organics. A second textbook exclusively dedicated to PLD was edited by Rob Eason in 2007 [4], reviewing many possible modifications and extensions of the method. To celebrate 25 years of pulsed laser deposition, Venkatesan organized a symposium on 'Recent Advances in the Pulsed Laser Deposition of Thin Films and Nanostructures' in 2013 [5]. Besides dielectric, ferroelectric and magnetic oxides, the wide-bandgap group II-VI semiconductor ZnO is among the most intensively researched compounds during the last decade. Therefore, this material has become the subject of two introductory reviews in this issue by Opel et al and Tsukazaki et al , to show the state-of-the-art work carried out on ZnO thin films to 2013. The detailed insights into growth parameter control and their impact on the ZnO film performance make both reviews highly instructional not only for specialists, but also for beginners in PLD. The perspective of PLD towards industrial applications largely depends, first, on the ability of the excimer laser suppliers to further increase the laser power and, second, on the deposition schemes to distribute the ablated material homogeneously on technologically relevant substrate areas (8-inch diameter). These developments are explained here by the leading companies dealing with high-power excimer lasers and large-area PLD equipment, such as Coherent Laser Systems GmbH, PVD Products, Inc., and SolMateS B.V. It is also important to note the efforts made by Blank and Rijnders for atomic layer control of PLD by in situ high-pressure reflection high-energy electron diffraction (RHEED), which is now adopted by many groups worldwide. The potential of multi-beam PLD for advanced optical waveguides and of advanced design

  2. Short pulse laser systems for biomedical applications

    CERN Document Server

    Mitra, Kunal


    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...

  3. Pinched propagation of high-power, pulsed electron beams for welding and materials processing applications (United States)

    Fernsler, Richard F.; Hubbard, Richard F.; Lampe, Martin


    Electron beams are used commercially as intense heating sources for welding and related materials processing applications. The beams used for welding operate continuously with energy up to 200 keV and current approximately 1 A. Because these beams are severely degraded by propagation in air over any substantial range, most present-day electron-beam welders require vacuum pumping and precision focusing, which has severely restricted utilization of the technology. Over the past few decades, a different class of electron-beam generators has been developed that produces pulsed beams with energies of several MeV, currents of 1 kA or more, radii as small as 1 mm, pulse lengths of tens of ns, and pulse repetition rates up to several kHz. We show here that beams of this type can propagate in ambient air, in a tightly pinched mode and with acceptable stability, over distances of a few tens of cm. We determine the constraints on the choice of beam parameters, due mainly to the effects of gas scattering and the resistive instability. We show that stability can be enhanced, and the acceptable parameter range extended considerably, by using a narrow conducting pipe filled with air or another gas to guide the beam to the workpiece.

  4. Pulsed Laser Annealing of Carbon (United States)

    Abrahamson, Joseph P.

    This dissertation investigates laser heating of carbon materials. The carbon industry has been annealing carbon via traditional furnace heating since at least 1800, when Sir Humphry Davy produced an electric arc with carbon electrodes made from carbonized wood. Much knowledge has been accumulated about carbon since then and carbon materials have become instrumental both scientifically and technologically. However, to this day the kinetics of annealing are not known due to the slow heating and cooling rates of furnaces. Additionally, consensus has yet to be reached on the cause of nongraphitizability. Annealing trajectories with respect to time at temperature are observed from a commercial carbon black (R250), model graphitizable carbon (anthracene coke) and a model nongraphitizable carbon (sucrose char) via rapid laser heating. Materials were heated with 1064 nm and 10.6 im laser radiation from a Q-switched Nd:YAG laser and a continuous wave CO2 laser, respectively. A pulse generator was used reduce the CO2 laser pulse width and provide high temporal control. Time-temperature-histories with nanosecond temporal resolution and temperature reproducibility within tens of degrees Celsius were determined by spectrally resolving the laser induced incandescence signal and applying multiwavelength pyrometry. The Nd:YAG laser fluences include: 25, 50, 100, 200, 300, and 550 mJ/cm2. The maximum observed temperature ranged from 2,400 °C to the C2 sublimation temperature of 4,180 °C. The CO2 laser was used to collect a series of isothermal (1,200 and 2,600 °C) heat treatments versus time (100 milliseconds to 30 seconds). Laser heated samples are compared to furnace annealing at 1,200 and 2,600 °C for 1 hour. The material transformation trajectory of Nd:YAG laser heated carbon is different than traditional furnace heating. The traditional furnace annealing pathway is followed for CO2 laser heating as based upon equivalent end structures. The nanostructure of sucrose char

  5. Ex vivo efficacy evaluation of laser vaporization for treatment of benign prostatic hyperplasia using a 300-W high-power laser diode with a wavelength of 980 nm (United States)

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao


    Background and Objective: Laser vaporization of the prostate is considered to be a promising treatment for benign prostatic hyperplasia (BPH), and efficiency of vaporization and hemostasis are both important parameters for such treatment. In this study, we used a high-power laser diode with a wavelength of 980 nm to obtain high vaporization efficiency with good hemostasis. The objective of this study is to evaluate the efficacy of laser vaporization for treatment of BPH in ex vivo experiments using a 300-W high-power laser diode with a wavelength of 980 nm quantitatively. Materials and Methods: An ex vivo experimental setup simulating clinical treatment situation was constructed. Bovine prostate tissue was used as a sample. The power setting was 100, 150, 200, 250, or 300 W, and the irradiation time was 0.5, 1, or 2 s. After laser irradiation, vaporized and coagulated depths were measured. Results: The vaporized depth increased with the laser power and irradiation time, and the results confirmed that the high-power laser diode could efficiently vaporize the prostate tissue. Coagulated depth increased as the laser power became higher. Conclusions: Laser vaporization of prostate tissue using a high-power laser diode with a wavelength of 980 nm represents a promising treatment for BPH; this method exhibits high vaporization efficiency and good hemostasis. However, operators must be aware of the risk of postoperative perforation of the prostatic capsule caused by coagulation of deep regions that cannot be visualized by endoscopic observation. PMID:25368442

  6. Ex vivo efficacy evaluation of laser vaporization for treatment of benign prostatic hyperplasia using a 300-W high-power laser diode with a wavelength of 980 nm. (United States)

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao; Awazu, Kunio


    Laser vaporization of the prostate is considered to be a promising treatment for benign prostatic hyperplasia (BPH), and efficiency of vaporization and hemostasis are both important parameters for such treatment. In this study, we used a high-power laser diode with a wavelength of 980 nm to obtain high vaporization efficiency with good hemostasis. The objective of this study is to evaluate the efficacy of laser vaporization for treatment of BPH in ex vivo experiments using a 300-W high-power laser diode with a wavelength of 980 nm quantitatively. An ex vivo experimental setup simulating clinical treatment situation was constructed. Bovine prostate tissue was used as a sample. The power setting was 100, 150, 200, 250, or 300 W, and the irradiation time was 0.5, 1, or 2 s. After laser irradiation, vaporized and coagulated depths were measured. The vaporized depth increased with the laser power and irradiation time, and the results confirmed that the high-power laser diode could efficiently vaporize the prostate tissue. Coagulated depth increased as the laser power became higher. Laser vaporization of prostate tissue using a high-power laser diode with a wavelength of 980 nm represents a promising treatment for BPH; this method exhibits high vaporization efficiency and good hemostasis. However, operators must be aware of the risk of postoperative perforation of the prostatic capsule caused by coagulation of deep regions that cannot be visualized by endoscopic observation.

  7. Propagating Characteristics of Pulsed Laser in Rain

    Directory of Open Access Journals (Sweden)

    Jing Guo


    Full Text Available To understand the performance of laser ranging system under the rain weather condition, we need to know the propagating characteristics of laser pulse in rain. In this paper, the absorption and attenuation coefficients were calculated based on the scattering theories in discrete stochastic media, and the propagating characteristics of laser pulse in rain were simulated and analyzed using Monte-Carlo method. Some simulation results were verified by experiments, and the simulation results are well matched with the experimental data, with the maximal deviation not less than 7.5%. The results indicated that the propagating laser beam would be attenuated and distorted due to the scattering and absorption of raindrops, and the energy attenuation and pulse shape distortion strongly depended on the laser pulse widths.

  8. First high power pulsed tests of a dressed 325 MHz superconducting single spoke resonator at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Madrak, R.; Branlard, J.; Chase, B.; Darve, C.; Joireman, P.; Khabiboulline, T.; Mukherjee, A.; Nicol, T.; Peoples-Evans, E.; Peterson, D.; Pischalnikov, Y.; /Fermilab


    In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, {beta} = 0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Q{sub ext} test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Q{sub ext} {approx} 10{sup 6} was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.

  9. Robust modeling and performance analysis of high-power diode side-pumped solid-state laser systems. (United States)

    Kashef, Tamer; Ghoniemy, Samy; Mokhtar, Ayman


    In this paper, we present an enhanced high-power extrinsic diode side-pumped solid-state laser (DPSSL) model to accurately predict the dynamic operations and pump distribution under different practical conditions. We introduce a new implementation technique for the proposed model that provides a compelling incentive for the performance assessment and enhancement of high-power diode side-pumped Nd:YAG lasers using cooperative agents and by relying on the MATLAB, GLAD, and Zemax ray tracing software packages. A large-signal laser model that includes thermal effects and a modified laser gain formulation and incorporates the geometrical pump distribution for three radially arranged arrays of laser diodes is presented. The design of a customized prototype diode side-pumped high-power laser head fabricated for the purpose of testing is discussed. A detailed comparative experimental and simulation study of the dynamic operation and the beam characteristics that are used to verify the accuracy of the proposed model for analyzing the performance of high-power DPSSLs under different conditions are discussed. The simulated and measured results of power, pump distribution, beam shape, and slope efficiency are shown under different conditions and for a specific case, where the targeted output power is 140 W, while the input pumping power is 400 W. The 95% output coupler reflectivity showed good agreement with the slope efficiency, which is approximately 35%; this assures the robustness of the proposed model to accurately predict the design parameters of practical, high-power DPSSLs.

  10. Temporal characterization of plasma cw high-power CO2 laser-matter interaction: contribution to the welding process control (United States)

    Engel, Thierry; Kane, M.; Fontaine, Joel


    During high-power laser welding, gas ionization occurs above the sample. The resulting plasma ignition threshold is related to ionization potential of metallic vapors from the sample, and shielding gases used in the process. In this work, we have characterized the temporal behavior of the radiation emitted by the plasma during laser welding in order to relate the observed signals to the process parameters.

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

    Directory of Open Access Journals (Sweden)

    Olafur Jonasson


    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.

  12. Solution for testing large high-power laser lenses having long focal length (Conference Presentation) (United States)

    Fappani, Denis; IDE, Monique


    Many high power laser facilities are in operation all around the world and include various tight optical components such as large focussing lenses. Such lenses exhibit generally long focal lengths which induces some issues for their optical testing during manufacturing and inspection. Indeed, their transmitted wave fronts need to be very accurate and interferometric testing is the baseline to achieve that. But, it is always a problem to manage simultaneously long testing distances and fine accuracies in such interferometry testing. Taking example of the large focusing lenses produced for the Orion experimentation at AWE (UK), the presentation will describe which kind of testing method has been developed to demonstrate simultaneously good performances with sufficiently good repeatability and absolute accuracy. Special emphasis will be made onto the optical manufacturing issues and interferometric testing solutions. Some ZEMAX results presenting the test set-up and the calibration method will be presented as well. The presentation will conclude with a brief overview of the existing "state of the art" at Thales SESO for these technologies.

  13. Experimental study of the mode instability onset threshold in high-power FA-LPF lasers. (United States)

    Malleville, Marie-Alicia; Dauliat, Romain; Benoît, Aurélien; Leconte, Baptiste; Darwich, Dia; Jeu, Rémi du; Jamier, Raphaël; Schuster, Kay; Roy, Philippe


    We report here on an experimental investigation of the temporal behavior of transverse mode instabilities into "fully aperiodic large-pitch fibers" (FA-LPFs) operated in high-power continuous-wave laser configuration. To ensure an effective transverse single-mode emission into FA-LPFs, a perfect index matching between the active core and the background cladding materials (Δn=0) is required. The original design of such fibers enables an effective transverse single-mode emission by strengthening the higher-order mode delocalization out of the gain region, even for high heat load levels, consequently leading to the improvement of the beam spatial quality. The study was conducted over fibers of various gain region diameters, from 58 to 100 μm, for a refractive index mismatch Δn of about +8×10-5. The emitted beam is characterized using both M2 measurements and time traces to study the changeover of a stable temporal behavior to an unstable one.

  14. High power master oscillator power amplifier (MOPA) AlGaAs laser for intersatellite communications (United States)

    Cornwell, Donald M., Jr.


    A master oscillator power amplifier (MOPA) configuration has been developed using an anti-reflection-coated AlGaAs semiconductor broad area laser in a reflective amplifier mode. For CW injection, the MOPA produced 340 mW of diffraction-limited power. The semiconductor MOPA configuration also produced peak diffraction-limited powers of 360 mW and 320 mW for quaternary pulse position Q-PPM modulation rates of 50 Mbps and 325 Mbps, respectively, for a peak injected power of 100 mW. Angular beamsteering during modulation was minimized by collimating the injected beam. The diffraction-limited peak power was limited by the frequency chirp of the master oscillator and also by the coupling losses of the injected beam.

  15. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification. (United States)

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F


    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

  16. Laser beam welding of titanium nitride coated titanium using pulse-shaping

    Directory of Open Access Journals (Sweden)

    Milton Sergio Fernandes de Lima


    Full Text Available A new welding method which allows the assembly of two titanium nitride coated titanium parts is proposed. The welding procedure utilizes the possibility for pulse-shaping in order to change the energy distribution profile during the laser pulse. The pulse-shaping is composed of three elements: a a short high power pulse for partial ablation at the surface; b a long pulse for thermal penetration; and c a quenching slope for enhanced weldability. The combination of these three elements produces crack-free welds. The weld microstructure is changed in comparison to normal welding, i.e. with a rectangular pulse, as the nitrogen and the microhardness are more homogenously distributed in the weld under pulse-shaping conditions. This laser pulse dissolves the TiN layer and allows nitrogen to diffuse into the melt pool, also contributing to an enhanced weldability by providing suitable thermal conditions.

  17. Laser Pulses Characterization with Pyroelectric Sensors


    Malka, V.; J. Faure; Y. Gauduel


    There are many industrial and medical applications of CO2 (λ=10.6 μm) and Nd:YAG (λ=1.06 μm) infrared lasers for which the quality of the process are tightly connected to the characteristic of the laser pulse. These two types of lasers deliver pulses with duration, repetition frequency and power that can be controlled by means of a programmable electronic control unit. An open-loop control generally optimize the process performances by availing of a laser system model. How...

  18. Evolution Strategies for Laser Pulse Compression

    NARCIS (Netherlands)

    Monmarché, Nicolas; Fanciulli, Riccardo; Willmes, Lars; Talbi, El-Ghazali; Savolainen, Janne; Collet, Pierre; Schoenauer, Marc; van der Walle, P.; Lutton, Evelyne; Back, Thomas; Herek, Jennifer Lynn


    This study describes first steps taken to bring evolutionary optimization technology from computer simulations to real world experimentation in physics laboratories. The approach taken considers a well understood Laser Pulse Compression problem accessible both to simulation and laboratory

  19. High-power diode lasers at 1178  nm with high beam quality and narrow spectra. (United States)

    Paschke, K; Bugge, F; Blume, G; Feise, D; Erbert, G


    High-power distributed Bragg reflector tapered diode lasers (DBR-TPLs) at 1180 nm were developed based on highly strained InGaAs quantum wells. The lasers emit a nearly diffraction-limited beam with more than two watts with a narrow spectral width. These features are believed to make this type of diode laser a key component for the manufacturing of miniaturized laser modules in the yellow and orange spectral range by second-harmonic generation to cover a spectral region currently not accessible with direct emitting diode lasers. Future applications might be the laser-cooling of sodium, high-resolution glucose-content measurements, as well as spectroscopy on rare earth elements.

  20. Tunable compensation of GVD-induced FM-AM conversion in the front end of high-power lasers. (United States)

    Li, Rao; Fan, Wei; Jiang, Youen; Qiao, Zhi; Zhang, Peng; Lin, Zunqi


    Group velocity dispersion (GVD) is one of the main factors leading to frequency modulation (FM) to amplitude modulation (AM) conversion in the front end of high-power lasers. In order to compensate the FM-AM modulation, the influence of GVD, which is mainly induced by the phase filter effect, is theoretically investigated. Based on the theoretical analysis, a high-precision, high-stability, tunable GVD compensatory using gratings is designed and experimentally demonstrated. The results indicate that the compensator can be implemented in high-power laser facilities to compensate the GVD of fiber with a length between 200-500 m when the bandwidth of a phase-modulated laser is 0.34 nm or 0.58 nm and the central wavelength is in the range of 1052.3217-1053.6008 nm. Due to the linear relationship between the dispersion and the spacing distance of the gratings, the compensator can easily achieve closed-loop feedback controlling. The proposed GVD compensator promises significant applications in large laser facilities, especially in the future polarizing fiber front end of high-power lasers.

  1. Pulse growth dynamics in laser mode locking (United States)

    Popov, Mark; Gat, Omri


    We analyze theoretically and numerically the nonlinear process of pulse formation in mode-locked lasers, starting from a perturbation of a continuous wave. Focusing on weak-to-moderate dispersion systems, we show that pulse growth is initially slow, dominated by a cascade of energy from low to high axial modes, followed by fast strongly nonlinear growth, and finally relaxation to the stable pulse wave form. The pulse grows initially by condensing a fixed amount of energy into a decreasing time interval, with peak power growing toward a finite-time singularity that is checked when the gain bandwidth is saturated by the pulse.

  2. AlGaInN laser diode bars for high-power, optical integration and quantum technologies (United States)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Stanczyk, S.; Wisniewski, P.; Czernecki, R.; Schiavon, D.; Leszczyński, M.


    GaN laser diodes fabricated from the AlGaInN material system is an emerging technology for high power, optical integration and quantum applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., 380nm, to the visible 530nm, by tuning the indium content of the laser GaInN quantum well, giving rise to new and novel applications including displays and imaging systems, free-space and underwater telecommunications and the latest quantum technologies such as optical atomic clocks and atom interferometry.

  3. Optical and X-ray emission spectroscopy of high-power laser-induced dielectric breakdown in molecular gases and their mixtures. (United States)

    Babankova, Dagmar; Civis, Svatopluk; Juha, Libor; Bittner, Michal; Cihelka, Jaroslav; Pfeifer, Miroslav; Skala, Jirí; Bartnik, Andrzej; Fiedorowicz, Henryk; Mikolajczyk, Janusz; Ryć, Leszek; Sedivcova, Tereza


    Large-scale plasma was created in molecular gases (CO, CO2, N2, H2O) and their mixtures by high-power laser-induced dielectric breakdown (LIDB). Compositions of the mixtures used are those suggested for the early earth's atmosphere of neutral and/or mildly reducing character. Time-integrated optical spectra emitted from the laser spark have been measured and analyzed. The spectra of the plasma generated in the CO-containing mixtures are dominated by emission of both C2 and CN radicals. A vibrational temperature of approximately 10(4) K was determined according to an intensity distribution in a vibronic structure of the CN (B2Sigma(+)u-X2Sigma(+)g) violet band. For comparison, the NH3-CH4-H2-H2O mixture has been irradiated as a model of the strongly reducing version of the early earth's atmosphere. In this mixture, excited CN seems to be significantly less abundant than C2. The LIDB experiments were in the molecular gases carried out not only in the static cell but also using a large, double stream pulse jet (gas puff target) placed in the vacuum interaction chamber. The obtained soft X-ray emission spectra indicate the presence of highly charged atomic ions in the hot core of high-power laser sparks.

  4. Extending ultra-short pulse laser texturing over large area

    Energy Technology Data Exchange (ETDEWEB)

    Mincuzzi, G., E-mail:; Gemini, L.; Faucon, M.; Kling, R.


    Highlights: • We carried out metal surface texturing (Ripples, micro grooves, Spikes) using a high power, high repetition rate, industrial, Ultra-short pulses laser. • Extremely Fast processing is shown (Laser Scan speed as high as 90 m/s) with a polygon scanner head. • Stainless steel surface blackening with Ultra-short pulses laser has been obtained with unprecedented scanspeed. • Full SEM surface characterization was carried out for all the different structures obtained. • Reflectance measurements were carried out to characterize surface reflectance. - Abstract: Surface texturing by Ultra-Short Pulses Laser (UPL) for industrial applications passes through the use of both fast beam scanning systems and high repetition rate, high average power P, UPL. Nevertheless unwanted thermal effects are expected when P exceeds some tens of W. An interesting strategy for a reliable heat management would consists in texturing with a low fluence values (slightly higher than the ablation threshold) and utilising a Polygon Scanner Heads delivering laser pulses with unrepeated speed. Here we show for the first time that with relatively low fluence it is possible over stainless steel, to obtain surface texturing by utilising a 2 MHz femtosecond laser jointly with a polygonal scanner head in a relatively low fluence regime (0.11 J cm{sup −2}). Different surface textures (Ripples, micro grooves and spikes) can be obtained varying the scan speed from 90 m s{sup −1} to 25 m s{sup −1}. In particular, spikes formation process has been shown and optimised at 25 m s{sup −1} and a full morphology characterization by SEM has been carried out. Reflectance measurements with integrating sphere are presented to compare reference surface with high scan rate textures. In the best case we show a black surface with reflectance value < 5%.

  5. Bringing Pulsed Laser Welding into Production

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove


    In this paper, some research and develop-ment activities within pulsed laser welding technology at the Tech-nical University of Denmark will be described. The laser group at the Insti-tute for Manufacturing Technology has nearly 20 years of experience in laser materials process-ing. Inter......-nationally the group is mostly known for its contri-butions to the development of the laser cutting process, but further it has been active within laser welding, both in assisting industry in bringing laser welding into production in several cases and in performing fundamental R & D. In this paper some research...... activities concerning the weldability of high alloyed austenitic stainless steels for mass production industry applying industrial lasers for fine welding will be described. Studies on hot cracking sensitivity of high alloyed austenitic stainless steel applying both ND-YAG-lasers and CO2-lasers has been...

  6. Elucidation of Metallic Plume and Spatter Characteristics Based on SVM During High-Power Disk Laser Welding (United States)

    Gao, Xiangdong; Liu, Guiqian


    During deep penetration laser welding, there exist plume (weak plasma) and spatters, which are the results of weld material ejection due to strong laser heating. The characteristics of plume and spatters are related to welding stability and quality. Characteristics of metallic plume and spatters were investigated during high-power disk laser bead-on-plate welding of Type 304 austenitic stainless steel plates at a continuous wave laser power of 10 kW. An ultraviolet and visible sensitive high-speed camera was used to capture the metallic plume and spatter images. Plume area, laser beam path through the plume, swing angle, distance between laser beam focus and plume image centroid, abscissa of plume centroid and spatter numbers are defined as eigenvalues, and the weld bead width was used as a characteristic parameter that reflected welding stability. Welding status was distinguished by SVM (support vector machine) after data normalization and characteristic analysis. Also, PCA (principal components analysis) feature extraction was used to reduce the dimensions of feature space, and PSO (particle swarm optimization) was used to optimize the parameters of SVM. Finally a classification model based on SVM was established to estimate the weld bead width and welding stability. Experimental results show that the established algorithm based on SVM could effectively distinguish the variation of weld bead width, thus providing an experimental example of monitoring high-power disk laser welding quality.

  7. High-power diode lasers between 1.8μm and 3.0μm for military applications (United States)

    Hilzensauer, S.; Giesin, C.; Schleife, J.; Gilly, J.; Patterson, S.; Kelemen, M. T.


    Over the last years high-power diode lasers in the wavelength window between 1.8μm and 3.0μm have demonstrated impressive characteristics in terms of output power, beam quality and efficiency. This facilitates the realization of compact and efficient light sources for use in the field of infrared countermeasures (IRCM), optically pumped semiconductor lasers emitting in the 2-4μm regime, low probability of intercept communication links, and trace gas analysis. The small size of a diode laser chip of typically less than a square millimeter allows for the fabrication of compact scalable laser modules with output powers of up to 140W. We will present results on MBE grown (AlGaIn)(AsSb) quantum-well diode laser single emitters and bars emitting between 1.8μm and 3.0μm. Different epitaxial and resonator designs have been investigated in cw and pulsed mode in order to meet industrial needs of high wall-plug and fiber-coupling efficiencies. More than 30% maximum wall-plug efficiency in cw operation for single emitters and laser bars has been reached together with output powers for single emitters of 2W (cw) and 9W (pulsed). The single emitters and bars are all suitable for fiber coupling. For a 1-bar module typical coupling efficiencies between 70% and 80% have been established for 400μm core fibers. In terms of output power, an AuSn soldered laser stack built of 10x 20% fill factor bars emitting at 1908nm, results in a record value of 140W at 58A in cw condition.

  8. A pulsed single-longitudinal-mode fiber laser based on gain control of pulse-injection-locked cavity (United States)

    Wan, Hongdan; Wu, Zhongwei; Sun, Xiaohan


    We achieve a pulsed fiber laser based on injecting a pulsed-seed into a high power fiber ring cavity consisting of two-stage amplifier chain. Through gain control of the fiber amplifier chain and adjustment of a variable optical coupler in the cavity, locking condition is satisfied which produce mode-hopping free, single-longitudinal-mode optical spectrum with 38 dB optical signal to noise ratio. The noise-free lasing RF spectrum has a 7.0 kHz 3 dB linewidth. The nanosecond lasing pulses are jittering-free with 40 W peak power at 1550 nm wavelength.

  9. High power laser source for atom cooling based on reliable telecoms technology with all fibre frequency stabilisation (United States)

    Legg, Thomas; Farries, Mark


    Cold atom interferometers are emerging as important tools for metrology. Designed into gravimeters they can measure extremely small changes in the local gravitational field strength and be used for underground surveying to detect buried utilities, mineshafts and sinkholes prior to civil works. To create a cold atom interferometer narrow linewidth, frequency stabilised lasers are required to cool the atoms and to setup and measure the atom interferometer. These lasers are commonly either GaAs diodes, Ti Sapphire lasers or frequency doubled InGaAsP diodes and fibre lasers. The InGaAsP DFB lasers are attractive because they are very reliable, mass-produced, frequency controlled by injection current and simply amplified to high powers with fibre amplifiers. In this paper a laser system suitable for Rb atom cooling, based on a 1560nm DFB laser and erbium doped fibre amplifier, is described. The laser output is frequency doubled with fibre coupled periodically poled LiNbO3 to a wavelength of 780nm. The output power exceeds 1 W at 780nm. The laser is stabilised at 1560nm against a fibre Bragg resonator that is passively temperature compensated. Frequency tuning over a range of 1 GHz is achieved by locking the laser to sidebands of the resonator that are generated by a phase modulator. This laser design is attractive for field deployable rugged systems because it uses all fibre coupled components with long term proven reliability.

  10. The characterization of secondary lithium-ion battery degradation when operating complex, ultra-high power pulsed loads (United States)

    Wong, Derek N.

    The US Navy is actively developing all electric fleets, raising serious questions about what is required of onboard power supplies in order to properly power the ship's electrical systems. This is especially relevant when choosing a viable power source to drive high power propulsion and electric weapon systems in addition to the conventional loads deployed aboard these types of vessels. Especially when high pulsed power loads are supplied, the issue of maintaining power quality becomes important and increasingly complex. Conventionally, a vessel's electrical power is generated using gas turbine or diesel driven motor-generator sets that are very inefficient when they are used outside of their most efficient load condition. What this means is that if the generator is not being utilized continuously at its most efficient load capacity, the quality of the output power may also be effected and fall outside of the acceptable power quality limits imposed through military standards. As a solution to this potential problem, the Navy has proposed using electrochemical storage devices since they are able to buffer conventional generators when the load is operating below the generator's most efficient power level or able to efficiently augment a generator when the load is operating in excess of the generator's most efficient power rating. Specifically, the US Navy is interested in using commercial off-the-shelf (COTS) lithium-ion batteries within an intelligently controlled energy storage module that could act as either a prime power supply for on-board pulsed power systems or as a backup generator to other shipboard power systems. Due to the unique load profile of high-rate pulsed power systems, the implementation of lithium-ion batteries within these complex systems requires them to be operated at very high rates and the effects these things have on cell degradation has been an area of focus. There is very little published research into the effects that high power transient

  11. Quartz head contact laser fiber: a novel fiber for laser ablation of the prostate using the 980 nm high power diode laser. (United States)

    Shaker, Hassan S; Shoeb, Mohammed S; Yassin, Mohammed M; Shaker, Sayed H


    High power 980 nm diode laser ablation of the prostate using the side firing fiber has proven its efficiency and safety in treating lower urinary tract symptoms secondary to benign prostatic hyperplasia. Nevertheless, this procedure is associated with some drawbacks such as prolonged irritative symptoms and tissue sloughing. In this study we evaluated the clinical outcome of high power 980 nm diode laser ablation of the prostate using a new quartz head contact fiber, and compared it to the standard side firing fiber in a randomized fashion. A total of 120 patients with benign prostatic hyperplasia scheduled for high power 980 nm diode laser ablation of the prostate were randomized to receive treatment with the standard side firing fiber or the novel quartz head contact fiber between April 2009 and April 2010. Patients were followed for at least 6 months, although 7 were lost to followup. The side firing fiber and quartz head contact fiber groups demonstrated significant improvement in International Prostate Symptom Score (from 20 to 8.39 vs 21.63 to 9.91), International Prostate Symptom Score-quality of life (from 4.47 to 1.94 vs 4.57 to 1.98) and maximum flow rate (from 7.79 to 22.22 vs 8.93 to 29.63 ml per second), and decreased prostate volume (47.79% vs 55.54%) and prostate specific antigen (59.69% to 60.61%), respectively. Complications, postoperative passage of tissue remnants and irritative symptoms were significantly less in the quartz head contact fiber group, as was the number of fibers per case. The quartz head contact fiber can produce similarly good outcomes in ablating the prostate using the high power 980 nm diode laser compared to the side firing fiber, and with fewer complications and side effects. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  12. Impact of High-Power Pulsed Light on Microbial Contamination, Health Promoting Components and Shelf Life of Strawberries

    Directory of Open Access Journals (Sweden)

    Irina Buchovec


    Full Text Available The aim of this work is to evaluate the impact of high-power pulsed light (HPPL on the microbial control and nutritional properties of strawberries. Berries were treated with HPPL and afterwards analyzed in terms of microbial contamination, shelf life extension, antioxidant capacity, firmness, total phenolic, total anthocyanin and ascorbic acid content, and colour. Results indicate that the decontamination of strawberries by HPPL was significant compared to control. Naturally distributed mesophilic bacteria on the surface of strawberries were inactivated by 2.2 log, and inoculated Bacillus cereus and Listeria monocytogenes were inactivated by 1.5 and 1.1 log, respectively. Yeasts/microfungi distributed on the surface of strawberries were inactivated by 1 log. The shelf life of treated strawberries was extended by 2 days. The increase of temperature on the surface of fruit never exceeded 42 °C. No significantly important differences were observed in total phenolic, total anthocyanin and ascorbic acid content, and antioxidant capacity of strawberry fruits before and after pulsed light treatment. Moreover, no impact on the strawberry colour or firmness was found after HPPL treatment. In conclusion, HPPL is fast, effective, non-thermal and environmentally friendly technique which can be applied for microbial control of strawberries.

  13. High-power quantum-dot tapered tunable external-cavity lasers based on chirped and unchirped structures. (United States)

    Haggett, Stephanie; Krakowski, Michel; Montrosset, Ivo; Cataluna, Maria Ana


    A high-power tunable external cavity laser configuration with a tapered quantum-dot semiconductor optical amplifier at its core is presented, enabling a record output power for a broadly tunable semiconductor laser source in the 1.2 - 1.3 µm spectral region. Two distinct optical amplifiers are investigated, using either chirped or unchirped quantum-dot structures, and their merits are compared, considering the combination of tunability and high output power generation. At 1230 nm, the chirped quantum-dot laser achieved a maximum power of 0.62 W and demonstrated nearly 100-nm tunability. The unchirped laser enabled a tunability range of 32 nm and at 1254 nm generated a maximum power of 0.97 W, representing a 22-fold increase in output power compared with similar narrow-ridge external-cavity lasers at the same current density.

  14. Diode pumped 1kHz high power Nd:YAG laser with excellent beam quality

    NARCIS (Netherlands)

    Godfried, Herman; Godfried, H.P; Offerhaus, Herman L.


    The design and operation of a one kilohertz diode pumped all solid-state Nd:YAG master oscillator power amplifier system with a phase conjugate mirror is presented. The setup allows high power scaling without reduction in beam quality.

  15. Hybrid Pulsed Nd:YAG Laser (United States)

    Miller, Sawyer; Trujillo, Skyler; Fort Lewis College Laser Group Team

    This work concerns the novel design of an inexpensive pulsed Nd:YAG laser, consisting of a hybrid Kerr Mode Lock (KLM) and Q-switch pulse. The two pulse generation systems work independently, non simultaneously of each other, thus generating the ability for the user to easily switch between ultra-short pulse widths or large energy density pulses. Traditionally, SF57 glass has been used as the Kerr medium. In this work, novel Kerr mode-locking mediums are being investigated including: tellurite compound glass (TeO2), carbon disulfide (CS2), and chalcogenide glass. These materials have a nonlinear index of refraction orders of magnitude,(n2), larger than SF57 glass. The Q-switched pulse will utilize a Pockels cell. As the two pulse generation systems cannot be operated simultaneously, the Pockels cell and Kerr medium are attached to kinematic mounts, allowing for quick interchange between systems. Pulse widths and repetition rates will vary between the two systems. A goal of 100 picosecond pulse widths are desired for the mode-locked system. A goal of 10 nanosecond pulse widths are desired for the Q-switch system, with a desired repetition rate of 50 Hz. As designed, the laser will be useful in imaging applications.

  16. RF synchronized short pulse laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Fuwa, Yasuhiro, E-mail:; Iwashita, Yoshihisa; Tongu, Hiromu; Inoue, Shunsuke; Hashida, Masaki; Sakabe, Shuji [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Okamura, Masahiro [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Yamazaki, Atsushi [Graduate School of Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)


    A laser ion source that produces shortly bunched ion beam is proposed. In this ion source, ions are extracted immediately after the generation of laser plasma by an ultra-short pulse laser before its diffusion. The ions can be injected into radio frequency (RF) accelerating bucket of a subsequent accelerator. As a proof-of-principle experiment of the ion source, a RF resonator is prepared and H{sub 2} gas was ionized by a short pulse laser in the RF electric field in the resonator. As a result, bunched ions with 1.2 mA peak current and 5 ns pulse length were observed at the exit of RF resonator by a probe.

  17. Laser sources for polarized electron beams in cw and pulsed accelerators

    CERN Document Server

    Hatziefremidis, A; Fraser, D; Avramopoulos, H


    We report the characterization of a high power, high repetition rate, mode-locked laser system to be used in continuous wave and pulsed electron accelerators for the generation of polarized electron beams. The system comprises of an external cavity diode laser and a harmonically mode-locked Ti:Sapphire oscillator and it can provide up to 3.4 W average power, with a corresponding pulse energy exceeding 1 nJ at 2856 MHz repetition rate. The system is tunable between 770-785 and 815-835 nm with two sets of diodes for the external cavity diode laser. (author)

  18. Raman spectroscopy differentiates squamous cell carcinoma (SCC) from normal skin following treatment with a high-powered CO2 laser. (United States)

    Fox, Sara A; Shanblatt, Ashley A; Beckman, Hugh; Strasswimmer, John; Terentis, Andrew C


    The number of cases of non-melanoma skin cancer (NMSC), which include squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), continues to rise as the aging population grows. Mohs micrographic surgery has become the treatment of choice in many cases but is not always necessary or feasible. Ablation with a high-powered CO2 laser offers the advantage of highly precise, hemostatic tissue removal. However, confirmation of complete cancer removal following ablation is difficult. In this study we tested for the first time the feasibility of using Raman spectroscopy as an in situ diagnostic method to differentiate NMSC from normal tissue following partial ablation with a high-powered CO2 laser. Twenty-five tissue samples were obtained from eleven patients undergoing Mohs micrographic surgery to remove NMSC tumors. Laser treatment was performed with a SmartXide DOT Fractional CO2 Laser (DEKA Laser Technologies, Inc.) emitting a wavelength of 10.6 μm. Treatment levels ranged from 20 mJ to 1200 mJ total energy delivered per laser treatment spot (350 μm spot size). Raman spectra were collected from both untreated and CO2 laser-treated samples using a 785 nm diode laser. Principal Component Analysis (PCA) and Binary Logistic Regression (LR) were used to classify spectra as originating from either normal or NMSC tissue, and from treated or untreated tissue. Partial laser ablation did not adversely affect the ability of Raman spectroscopy to differentiate normal from cancerous residual tissue, with the spectral classification model correctly identifying SCC tissue with 95% sensitivity and 100% specificity following partial laser ablation, compared with 92% sensitivity and 60% selectivity for untreated NMSC tissue. The main biochemical difference identified between normal and NMSC tissue was high levels of collagen in the normal tissue, which was lacking in the NMSC tissue. The feasibility of a combined high-powered CO2 laser ablation, Raman diagnostic procedure for the

  19. Deuterium overloading of palladium wires by means of high power means of high power ms pulsed electrolysis and electromigration : suggestions of phase transition and related excess heat

    Energy Technology Data Exchange (ETDEWEB)

    Celani, F.; Spallone, A.; Tripodi, P.; Petrocchi, A.; Di Gioacchino, D. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Marini, P.; Di Stefani, V. [EURESIS, Rome (Italy); Pace, S. [Salerno Univ. (Italy). Dip. di Fisica; Mancini, A. [ORIM s.r.l., Macerata (Italy)


    A room-temperature hydrogen and deuterium loading of palladium wires by means of pulsed electrolysis and electromigration effect is described. The D/Pd atomic ratio has been measured by means of the dependence of the resistivity upon the D/Pd ratio. Values of the D/Pd ratio up to 0.95 or even higher have been reached in short times. A correlation between an anomalous temperature rise and a resistivity transition of the overloaded palladium clearly appears.

  20. Technical And Economical Aspects Of Integrating, Handling And Exploiting High Power Laser Beams In Industrial Welding Systems (United States)

    Sayegh, Georges


    Analysis of the different factors which affect the improvement of high power laser systems are presented. It concerns ; the laser sources and their power and mode structure stability, their pointing stability and their efficiency, the beam transport and handling with different morphologies of machines according to the dimensions of the parts and the production rate ; the control of the industrial process through a central computer which takes in charge all the functions of the machine. Next, factors to be considered in the economical analysis for installing high power laser systems are discussed ; this covers the investment cost for the source and the associated system, the cost for consummables, for maintenance for training and labor. Comparison of the investment cost as function of power for both laser and electrons beam welding, shows that, generally speaking, there are two regions of beam power : the first located at less than 3 to 4kW where the laser is more advantageous economically, the second located at higher than 10kW where the E.B. is more advantageous. An example of a multi-stations mock-up (12 welding heads) supplied by a single laser beam is finally presented. Located at about 20m from the laser source the welding heads receive the laser beam through a distributor of high alignement precision. A spot weld similar to what is usually obtained with resistance spot welding can be achieved in about 0,5 second. Some technical and scientific problems relative to this application and concerning the transfer of laser beam are presented.

  1. Wettability characteristics of carbon steel modified with CO2, Nd:YAG, Excimer and high power diode lasers


    Lawrence, Jonathan; Li, Lin


    Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of a common mild steel (EN8) was found to effect changes in the wettability characteristics of the steel, namely changes in the measured contact angle. These modifications are related to changes in the surface roughness, changes in the surface oxygen content and changes in the surface energy of the mild steel. The wettability characteristics of the selected mild steel could be controll...

  2. Regimes of self-pulsing in photonic crystal Fano lasers

    DEFF Research Database (Denmark)

    Rasmussen, Thorsten Svend; Yu, Yi; Mørk, Jesper


    Laser self-pulsing was a property exclusive to macroscopic laser systems until recently, where self-pulsing laser operation was demonstrated experimentally and theoretically in a microscopic photonic crystal Fano laser [1]. We now provide a detailed theoretical analysis of the self-pulsing mechan......Laser self-pulsing was a property exclusive to macroscopic laser systems until recently, where self-pulsing laser operation was demonstrated experimentally and theoretically in a microscopic photonic crystal Fano laser [1]. We now provide a detailed theoretical analysis of the self...

  3. Investigations on fibers for high-peak power pulsed Nd:YAG-lasers for laser detonator (United States)

    Gao, Yang; Zhao, Xing-hai; Su, Wei; Cheng, Yong-sheng; Xu, Mei-jian; Duan, Wen-tao; Yu, Hai-wu


    For laser detonator application, high-peak power pulsed Nd:YAG laser is transmitted through all-silica optical fiber. The transmission properties of step-index fibers are investigated, using a high-peak power pulsed Nd: YAG rod laser with beyond 1MW power and Q-switch mode. The fibers are step-index multimode fibers with 400 or 600 μm core diameters, 440 or 660 μm cladding diameters. The power delivery characteristics were studied by theory and experiments. The results show that the fiber core diameter, NA, length and so on affect the transmission efficiency for high power laser. When the laser power is beyond a certain threshold, the SRS and SBS will be serious; the quantity of fiber end-face limits to the raising of laser power passing through fibers; the zero-probability damage threshold is calculated according to ISO/DIS standard 11254-1.2, which is 58.6J/cm2. Energy distribution of output beam from fibers will be uniform. Even the fiber end-face was partly damaged, laser power is still deliverable, and the transmission efficiency is related to the fiber damage grade.

  4. Intracavity optical refrigeration to 131K using high-power vertical external-cavity surface-emitting lasers (VECSELs) (United States)

    Ghasemkhani, Mohammadreza; Albrecht, Alexander R.; Melgaard, Seth D.; Seletskiy, Denis V.; Cedeberg, Jeffrey G.; Sheik-Bahae, Mansoor


    Laser cooling of Yb:YLF crystal to 131 K from room temperature has been demonstrated in an active intracavity arrangement for enhanced pump absorption. The laser is a high-power, broadly-tunable InGaAs/GaAs MQW VECSEL capable of producing 20 Watts at 1020 nm, directly at the E4-E5 transition of the Yb-ion. This is the coldest temperature achieved to date in an intracavity geometry and without sophisticated heat load management of the crystal. This progress presents a significant advancement towards an all-solid-state compact cryocooler.

  5. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.


    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659 to 675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than...... 0.07 nm throughout the tuning range, and the beam quality factor M2 is 2.0 with the output power of 1.27 W....

  6. High-power single spatial mode AlGaAs channeled-substrate-planar semiconductor diode lasers for spaceborne communications (United States)

    Connolly, J. C.; Carlin, D. B.; Ettenberg, M.


    A high power single spatial mode channeled substrate planar AlGaAs semiconductor diode laser was developed. The emission wavelength was optimized at 860 to 880 nm. The operating characteristics (power current, single spatial mode behavior, far field radiation patterns, and spectral behavior) and results of computer modeling studies on the performance of the laser are discussed. Reliability assessment at high output levels is included. Performance results on a new type of channeled substrate planar diode laser incorporating current blocking layers, grown by metalorganic chemical vapor deposition, to more effectively focus the operational current to the lasing region was demonstrated. The optoelectronic behavior and fabrication procedures for this new diode laser are discussed. The highlights include single spatial mode devices with up to 160 mW output at 8600 A, and quantum efficiencies of 70 percent (1 W/amp) with demonstrated operating lifetimes of 10,000 h at 50 mW.

  7. Ophthalmic applications of ultrashort pulsed lasers (United States)

    Juhasz, Tibor; Spooner, Greg; Sacks, Zachary S.; Suarez, Carlos G.; Raksi, Ferenc; Zadoyan, Ruben; Sarayba, Melvin; Kurtz, Ronald M.


    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.

  8. High-power helium-neon laser irradiation inhibits the growth of traumatic scars in vitro and in vivo. (United States)

    Shu, Bin; Ni, Guo-Xin; Zhang, Lian-Yang; Li, Xiang-Ping; Jiang, Wan-Ling; Zhang, Li-Qun


    This study explored the inhibitory effect of the high-power helium-neon (He-Ne) laser on the growth of scars post trauma. For the in vitro study, human wound fibroblasts were exposed to the high-power He-Ne laser for 30 min, once per day with different power densities (10, 50, 100, and 150 mW/cm(2)). After 3 days of repeated irradiation with the He-Ne laser, fibroblast proliferation and collagen synthesis were evaluated. For in vivo evaluation, a wounded animal model of hypertrophic scar formation was established. At postoperative day 21, the high-power He-Ne laser irradiation (output power 120 mW, 6 mm in diameter, 30 min each session, every other day) was performed on 20 scars. At postoperative day 35, the hydroxyproline content, apoptosis rate, PCNA protein expression and FADD mRNA level were assessed. The in vitro study showed that the irradiation group that received the power densities of 100 and 150 mW/cm(2) showed decreases in the cell proliferation index, increases in the percentage of cells in the G0/G1 phase, and decreases in collagen synthesis and type I procollagen gene expression. In the in vivo animal studies, regions exposed to He-Ne irradiation showed a significant decrease in scar thickness as well as decreases in hydroxyproline levels and PCNA protein expression. Results from the in vitro and in vivo studies suggest that repeated irradiation with a He-Ne laser at certain power densities inhibits fibroblast proliferation and collagen synthesis, thereby inhibits the growth of hypertrophic scars.

  9. Tunable High-Power Single-Frequency Laser at 2050 nm Project (United States)

    National Aeronautics and Space Administration — We propose a novel new architecture for a low-phase noise electronically tunable laser single-frequency laser at 2.05 microns that meets all the demanding...

  10. High-power ultralong-wavelength Tm-doped silica fiber laser cladding-pumped with a random distributed feedback fiber laser. (United States)

    Jin, Xiaoxi; Du, Xueyuan; Wang, Xiong; Zhou, Pu; Zhang, Hanwei; Wang, Xiaolin; Liu, Zejin


    We demonstrated a high-power ultralong-wavelength Tm-doped silica fiber laser operating at 2153 nm with the output power exceeding 18 W and the slope efficiency of 25.5%. A random distributed feedback fiber laser with the center wavelength of 1173 nm was employed as pump source of Tm-doped fiber laser for the first time. No amplified spontaneous emissions or parasitic oscillations were observed when the maximum output power reached, which indicates that employing 1173 nm random distributed feedback fiber laser as pump laser is a feasible and promising scheme to achieve high-power emission of long-wavelength Tm-doped fiber laser. The output power of this Tm-doped fiber laser could be further improved by optimizing the length of active fiber, reflectivity of FBGs, increasing optical efficiency of pump laser and using better temperature management. We also compared the operation of 2153 nm Tm-doped fiber lasers pumped with 793 nm laser diodes, and the maximum output powers were limited to ~2 W by strong amplified spontaneous emission and parasitic oscillation in the range of 1900-2000 nm.

  11. Drop shaping by laser-pulse impact

    CERN Document Server

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke


    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  12. Compression and radiation of high-power short rf pulses. II. A novel antenna array design with combined compressor/radiator elements

    KAUST Repository

    Sirenko, Kostyantyn


    The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a radiator. The studies on the monopole antenna demonstrate the possibility of a high power short RF pulse\\'s efficient radiation even using simple antennas. The studies on the novel array design demonstrate that a reduced size array with lower pulse distortion and power decay can be constructed by assembling the array from elements each of which integrates a compressor and a radiator. This design idea can be used with any type of antenna array; in this work it is applied to a phased array.

  13. Noncontact measurement of substrate temperature by optical low-coherence interferometry in high-power pulsed magnetron sputtering (United States)

    Hattori, Katsuhiro; Ohta, Takayuki; Oda, Akinori; Kousaka, Hiroyuki


    Substrate temperature is one of the important parameters that affect the quality of deposited films. The monitoring of the substrate temperature is an important technique of controlling the deposition process precisely. In this study, the Si substrate temperature in high-power pulse magnetron sputtering (HPPMS) was measured by a noncontact method based on optical low-coherence interferometry (LCI). The measurement was simultaneously performed using an LCI system and a thermocouple (TC) as a contact measurement method. The difference in measured value between the LCI system and the TC was about 7.4 °C. The reproducibilities of measurement for the LCI system and TC were ±0.7 and ±2.0 °C, respectively. The heat influx from the plasma to the substrate was estimated using the temporal variation of substrate temperature and increased from 19.7 to 160.0 mW/cm2 with increasing target applied voltage. The major factor for the enhancement of the heat influx would be charged species such as ions and electrons owing to the high ionization degree of sputtered metal particles in HPPMS.

  14. Sliding wear resistance of metal matrix composite layers prepared by high power laser

    NARCIS (Netherlands)

    Ocelik, Vaclav; Matthews, D; de Hosson, Jeff


    Two laser surface engineering techniques, Laser Cladding and Laser Melt Injection (LMI), were used to prepare three different metal matrix composite layers with a thickness of about 1 mm and approximately 25-30% volume fraction of ceramic particles. SiC/Al-8Si, WC/Ti-6Al-4V and TiB2/Ti-6Al-4V layers

  15. Pulsed laser illumination of photovoltaic cells (United States)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.


    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic receivers to provide remote power. Both the radio-frequency (RF) and induction FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL format.

  16. Ultrashort laser pulse driven inverse free electron laser accelerator experiment

    Directory of Open Access Journals (Sweden)

    J. T. Moody


    Full Text Available In this paper we discuss the ultrashort pulse high gradient inverse free electron laser accelerator experiment carried out at the Lawrence Livermore National Laboratory which demonstrated gradients exceeding 200  MV/m using a 4 TW 100 fs long 800 nm Ti:Sa laser pulse. Due to the short laser and electron pulse lengths, synchronization was determined to be one of the main challenges in this experiment. This made necessary the implementation of a single-shot, nondestructive, electro-optic sampling based diagnostics to enable time-stamping of each laser accelerator shot with <100  fs accuracy. The results of this experiment are expected to pave the way towards the development of future GeV-class IFEL accelerators.

  17. Laser breakdown in air at ultrahigh laser pulse repetition rates

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, Vitalii V; Kononenko, Taras V; Pashinin, V P; Gololobov, V M; Konov, Vitalii I [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)


    Some specific features of interaction of intense femtosecond laser pulses with air at ultrahigh pulse repetition rates have been experimentally studied. Data on the dynamics of plasma cloud expansion and the plasma electron density on time intervals no longer than 10 ns are obtained by femtosecond interferometry. These data are interpreted in terms of the most likely mechanisms of ionised gas recombination. The effect of ultrahigh-frequency laser radiation on a medium was modelled by double-pulse irradiation with a short delay {Delta}t between the pulses: from 1 ps to 11 ns. A nonmonotonic dependence of the degree of air ionisation by the second pulse on the delay time {Delta}t is found; possible mechanisms of these dependences are discussed in terms of the processes of femtosecond radiation absorption in the residual plasma. (extreme light fields and their applications)

  18. Monolithic fiber coupler for high power diode laser bars: results of prototype (United States)

    Mitra, T.; Bagschik, K.; Kalkusinki, A.


    A novel micro optical element is introduced, allowing coupling of light from several emitters of a laser diode bar into an optical fiber at high brightness. The monolithic fiber coupler is designed with individual segments for each emitter of the laser diode bar, providing two refractive surfaces for each emitter. By means of the monolithic fiber coupler, very cost effective fiber coupled laser diode modules based on bars are feasible. Consequently, approaches based on laser diodes bars can also compete with single emitter solutions for pumping application. Further applications of laser modules with monolithic fiber couplers may also be for direct material processing or as components in projection and illumination systems.

  19. Life prediction of 808nm high power semiconductor laser by accelerated life test of constant current stress (United States)

    Yao, Nan; Li, Wei; Zhao, Yihao; Zhong, Li; Liu, Suping; Ma, Xiaoyu


    High power semiconductor laser is widely used because of its high transformation efficiency, good working stability, compact volume and simple driving requirements. Laser's lifetime is very long, but tests at high levels of stress can speed up the failure process and shorten the times to failure significantly. So accelerated life test is used here for forecasting the lifetime of 808nm CW GaAs/AlGaAs high power semiconductor laser that has an output power of 1W under 1.04A. Accelerated life test of constant current stress based on the Inverse Power Law Relationship was designed. Tests were conducted under 1.3A, 1.6A and 1.9A at room temperature. It is the first time that this method is used in the domestic research of laser's lifetime prediction. Applying Weibull Distribution to describe the lifetime distribution and analyzing the data of times to failure, characteristics lifetime's functional relationship model with current is achieved. Then the characteristics lifetime under normal current is extrapolated, which is 9473h. Besides, to confirm the validity of the functional relationship model, we conduct an additional accelerated life test under 1.75A. Based on this experimental data we calculated the characteristics lifetime corresponding to 1.75A that is 171h, while the extrapolated characteristics lifetime from the former functional relationship model is 162h. The two results shows 5% deviation that is very low and acceptable, which indicates that the test design is reasonable and authentic.

  20. New pulsed laser data-acquisition system (United States)

    Singer, K. D.; Merlin, M. S.; Grossman, C. H.; Garito, A. F.


    A new pulsed laser data-acquisition system which can perform the normal operations of boxcar integrators is described. The system is based on a CAMAC standard photocurrent charge-sensitive integrator which is coupled to a laboratory minicomputer. The charge-sensitive integrator is triggered by a gate pulse which is optically synchronized to the laser output. This greatly reduces asynchronous noise. Details of the hardware configuration, the trigger gate circuit, and data averaging software are presented. Flexibility of hardware and software allow for other applications, such as multichannel analysis and other real time data processing.

  1. Green high-power tunable external-cavity GaN diode laser at 515 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael


    A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam...... incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode...

  2. Study of all-solid-state high-power continuous-wave tunable blue laser (United States)

    Wang, Shou-peng; Wang, Li; Mao, Li-qin; Tian, Hong-bin; Shan, Song; Dai, Jian-guang


    During the past few years, study of the all-solid-state blue laser has been focused on laser field applications in many fields and potential value of commerce. There has been much work done in order to obtain an efficient and simple solid-state blue laser source, this device being of interest for applications such as display technologies, production of high-density optical disk systems, high-resolution printing, or medical diagnostics. This paper discusses three means to realize all-solid-state blue lasers, including blue-emitting diode laser, direct frequency doubling of infrared laser diode (LD), diode-laser pumped all-solid-state blue lasers, respectively. However, direct emitters based on II - VI semiconductors are limited by the lifetime of laser diode. A practical and the most used way is the frequency-doubling of the 946-nm in Nd:YAG. In the field of nonlinear frequency conversion, we compare some different frequency-doubling crystals with improved optical characteristics, including higher nonlinear coefficient, wider transmission range, and more flexible phase-matching (PM) properties. Some nonlinear optical crystals usually used in solid-state laser are analyzed and compared, including KNbO 3, LBO, BBO, BiBO, CBO (CsB 3O 5), KBBF (KBe IIBO 3F II). The recent progress on solid-state blue laser has resulted research in from gain media, frequency-doubled crystals, and configurations of the cavities. Two difficulties which are the coating techniques and the blue noise problem (the fluctuation of the laser output power) in the development of solid-state lasers are pointed out, and the techniques of solving blue noise problem that have been usually used in the past research are presented.

  3. Stretching of picosecond laser pulses with uniform reflecting volume Bragg gratings (United States)

    Mokhov, Sergiy; Spiro, Alexander; Smirnov, Vadim; Kaim, Sergiy; Zeldovich, Boris; Glebov, Leonid


    This study shows that a uniform reflecting volume Bragg grating (VBG) can be used as a compact monolithic stretcher of high-power picosecond laser pulses, which is important for cases in which chirped Bragg gratings with the required chirp rate are difficult to fabricate. When an incident short pulse propagates along a grating and experiences local Bragg diffraction, a chirp-free reflected stretched pulse with an almost rectangular shape is generated. The increase in the duration of the reflected pulse is approximately equal to twice the propagation time along the grating. We derive an analytic expression for the diffraction efficiency, which incorporates the incident pulse duration, grating thickness, and amplitude of the refractive index modulation, enabling selection of the optimum grating for pulse stretching. Theoretical models of the extended pulse profiles are found to be in good agreement with experimental autocorrelation measurements. We also propose a simple and reliable method to control the temporal parameters of high-power picosecond pulses using the same laser source and a VBG of variable thickness, which can simplify experiments requiring different pulse durations significantly.

  4. Fatigue Testing of Materials by UV Pulsed Laser Irradiation

    CERN Document Server

    Calatroni, S; Taborelli, M


    The energy dissipated by the RF currents in the cavities of pulsed high-power linacs induces cycles of the surface temperature. In the case of the CLIC main linac the expected amplitude of the thermal cycles is above fifty degrees, for a total number of pulses reaching 1011. The differential thermal expansion due to the temperature gradient in the material creates a cyclic stress that can result in surface break-up by fatigue. The materials for cavity fabrication must therefore be selected in order to withstand such constraints whilst maintaining an acceptable surface state. The fatigue behaviour of Cu and CuZr alloy has been tested by inducing larger surface peak temperatures, thus reducing the number of cycles to failure, irradiating the surface with 40 ns pulses of UV light (308 nm) from an excimer laser. Surface break-up is observed after different number of laser shots as a function of the peak temperature. CuZr appears to withstand a much larger number of cycles than Cu, for equal peak temperature. The ...

  5. Laser triggering of water switches in terrawatt-class pulse power accelerators.

    Energy Technology Data Exchange (ETDEWEB)

    Woodworth, Joseph Ray; Johnson, David Lee (Titan Pulse Sciences, San Leandro, CA); Wilkins, Frank (Bechtel Nevada, Las Vegas, NV); Van De Valde, David (EG& G Technical Services, Albuquerque, NM); Sarkisov, Gennady Sergeevich (Ktech Corporation, Albuquerque, NM); Zameroski, Nathan D.; Starbird, Robert L. (Bechtel Nevada, Las Vegas, NV)


    Focused Beams from high-power lasers have been used to command trigger gas switches in pulse power accelerators for more than two decades. This Laboratory-Directed Research and Development project was aimed at determining whether high power lasers could also command trigger water switches on high-power accelerators. In initial work, we determined that focused light from three harmonics of a small pulsed Nd:YAG laser at 1064 nm, 532 nm, and 355 nm could be used to form breakdown arcs in water, with the lowest breakdown thresholds of 110 J/cm{sup 2} or 14 GW/cm{sup 2} at 532 nm in the green. In laboratory-scale laser triggering experiments with a 170-kV pulse-charged water switch with a 3-mm anode-cathode gap, we demonstrated that {approx}90 mJ of green laser energy could trigger the gap with a 1-{sigma} jitter of less than 2ns, a factor of 10 improvement over the jitter of the switch in its self breaking mode. In the laboratory-scale experiments we developed optical techniques utilizing polarization rotation of a probe laser beam to measure current in switch channels and electric field enhancements near streamer heads. In the final year of the project, we constructed a pulse-power facility to allow us to test laser triggering of water switches from 0.6- MV to 2.0 MV. Triggering experiments on this facility using an axicon lens for focusing the laser and a switch with a 740 kV self-break voltage produced consistent laser triggering with a {+-} 16-ns 1-{sigma} jitter, a significant improvement over the {+-} 24-ns jitter in the self-breaking mode.

  6. Interaction of high power laser beams with plasma in ICF hohlraum using the FDTD method (United States)

    Lin, Zhili


    In the indirect-drive Inertial confinement fusion (ICF) system, groups of laser beams are injected into a gold cylindrical hohlraum and plasma is stimulated with the ablation of the wall of hohlraum by the laser beams. In our work, the finite-difference time-domain (FDTD) method associated with the bilinear transform and Maclaurin series expansion approaches is utilized to examine the laser beam propagation in plasma described by the Drude model. The state-of-the-art approaches for generating the laser beams are presented and realized according to the full utilization of the TF/SF source condition. Base on the previous technologies, the quantitatively numerical analysis of the propagation characteristics of laser beams in the plasma is conducted. The obtained results are illustrated and discussed that are helpful for the parameter optimization of laser beams for an ICF system.

  7. Space debris removal using a high-power ground-based laser

    Energy Technology Data Exchange (ETDEWEB)

    Monroe, D.K.


    The feasibility of utilizing a ground-based laser without an orbital mirror for space debris removal is examined. Technical issues include atmospheric transmission losses, adaptive-optics corrections of wavefront distortions, laser field of view limitations, and laser-induced impulse generation. The physical constraints require a laser with megawatt output, long run-time capability, and wavelength with good atmospheric transmission characteristics. It is found that a 5-MW reactor-pumped laser can deorbit debris having masses of the order of one kilogram from orbital altitudes to be used by Space Station Freedom. Debris under one kilogram can be deorbited after one pass over the laser site, while larger debris can be deorbited or transferred to alternate orbits after multiple passes over the site.

  8. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser (United States)

    Hackel, Lloyd A.; Soules, Thomas F.; Fochs, Scott N.; Rotter, Mark D.; Letts, Stephan A.


    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  9. Neutralization of improvised explosive devices by high-power lasers: research results from the FP7 project ENCOUNTER (United States)

    Osterholz, J.; Lueck, M.; Lexow, B.; Wickert, M.


    The development of reliable techniques for the safe neutralization of improvised explosive devices (IEDs) is an active field of research. Recently, innovative approaches for the neutralization of IEDs were developed and tested within the FP7 project ENCOUNTER ("Explosive Neutralisation and Mitigation Countermeasures for IEDs in Urban/Civil Environment") and were compared to existing, established technologies. Here, the ENCOUNTER project is presented with a special focus on the neutralization of IEDs by high-power lasers. The working principle of the application of high-power lasers for the neutralization of explosive devices is based on thermal effects. Heating of the IEDs main charge may occur either by direct irradiation of the explosive material or by heat transfer through the main charge's confinement. The aim of the application of the laser is to achieve a low order burning reaction of the explosive charge and thus a controlled neutralization of the IED. Since laser beams allow for the directed transport of energy, this technique can be applied over long stand-off distances and has thus potential for an increase of the safety of clearing forces and population in the case of terroristic attacks in a civilian environment. Within the ENCOUNTER project, a laboratory environment has been set up which allows for the irradiation of IEDs with a laser power of up to 10 kW. Experiments have been carried out on a broad spectrum of different types of IEDs. The processes during neutralization were studied in detail with high-speed diagnostics. On the basis of these experimental data, the safety and the reliability of the application of the laser was analyzed, and recommendations to end users were given. In addition to the results of the ENCOUNTER project, approaches for the numerical simulation of the neutralization of IEDs are discussed.

  10. Optical injection and spectral filtering of high-power UV laser diodes

    CERN Document Server

    Schäfer, V M; Tock, C J; Lucas, D M


    We demonstrate injection-locking of 120mW laser diodes operating at 397nm. We achieve stable operation with injection powers of ~100uW and a slave laser output power of up to 110mW. We investigate the spectral purity of the slave laser light via photon scattering experiments on a single trapped Ca40 ion. We show that it is possible to achieve a scattering rate indistinguishable from that of monochromatic light by filtering the laser light with a diffraction grating to remove amplified spontaneous emission.

  11. 193nm high power lasers for the wide bandgap material processing (United States)

    Fujimoto, Junichi; Kobayashi, Masakazu; Kakizaki, Koji; Oizumi, Hiroaki; Mimura, Toshio; Matsunaga, Takashi; Mizoguchi, Hakaru


    Recently infrared laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer Level Package (FO-WLP) and Through Glass Via hole (TGV) which are hard to process with less defect. In this study, we investigated ablation rate with deep ultra violet excimer laser to explore its possibilities of micromachining on organic and glass interposers. These results were observed with a laser microscopy and Scanning Electron Microscope (SEM). As the ablation rates of both materials were quite affordable value, excimer laser is expected to be put in practical use for mass production.

  12. Thin film surface processing by ultrashort laser pulses (USLP) (United States)

    Scorticati, D.; Skolski, J. Z. P.; Römer, G. R. B. E.; Huis in't Veld, A. J.; Workum, M.; Theelen, M.; Zeman, M.


    In this work, we studied the feasibility of surface texturing of thin molybdenum layers on a borosilicate glass substrate with Ultra-Short Laser Pulses (USLP). Large areas of regular diffraction gratings were produced consisting of Laserinduced periodic surface structures (LIPSS). A short pulsed laser source (230 fs-10 ps) was applied using a focused Gaussian beam profile (15-30 μm). Laser parameters such as fluence, overlap (OL) and Overscans (OS), repetition frequency (100-200 kHz), wavelength (1030 nm, 515 nm and 343 nm) and polarization were varied to study the effect on periodicity, height and especially regularity of LIPSS obtained in layers of different thicknesses (150-400 nm). The aim was to produce these structures without cracking the metal layer and with as little ablation as possible. It was found that USLP are suitable to reach high power densities at the surface of the thin layers, avoiding mechanical stresses, cracking and delamination. A possible photovoltaic (PV) application could be found in texturing of thin film cells to enhance light trapping mechanisms.

  13. Control system of a high-power infrared free electron laser

    CERN Document Server

    Gorniker, E I; Kondakov, A A; Kurkin, G Ya


    The control system of the high power infrared FEL is built on the of a two-level distributed system.The system includes the operator interface at the upper level and Input/Output Controllers under supervision of the real time operating system at the lower level.All hardware for the control system of the FEL is produced by our institute,which solves several problems of hard real time and reduces cost of equipment.

  14. Non-solid non-rigid optics for high-power laser systems

    CSIR Research Space (South Africa)

    Michaelis, MM


    Full Text Available Non-solid and non-rigid optics employ gas and liquid transmission and reflection, as well as flexible membranes to influence laser beams, laser driven particle beams and harmonic generators. Some examples are acoustic gratings, phase conjugate...

  15. A High Power, Frequency Tunable Colloidal Quantum Dot (CdSe/ZnS) Laser. (United States)

    Prasad, Saradh; AlHesseny, Hanan Saleh; AlSalhi, Mohamad S; Devaraj, Durairaj; Masilamai, Vadivel


    Tunable lasers are essential for medical, engineering and basic science research studies. Most conventional solid-state lasers are capable of producing a few million laser shots, but limited to specific wavelengths, which are bulky and very expensive. Dye lasers are continuously tunable, but exhibit very poor chemical stability. As new tunable, efficient lasers are always in demand, one such laser is designed with various sized CdSe/ZnS quantum dots. They were used as a colloid in tetrahydrofuran to produce a fluorescent broadband emission from 520 nm to 630 nm. The second (532 nm) and/or third harmonic (355 nm) of the Nd:YAG laser (10 ns, 10 Hz) were used together as the pump source. In this study, different sized quantum dots were independently optically pumped to produce amplified spontaneous emission (ASE) with 4 nm to 7 nm of full width at half-maximum (FWHM), when the pump power and focusing were carefully optimized. The beam was directional with a 7 mrad divergence. Subsequently, these quantum dots were combined together, and the solution was placed in a resonator cavity to obtain a laser with a spectral width of 1 nm and tunable from 510 to 630 nm, with a conversion efficiency of about 0.1%.

  16. Efficient high power operation of erbium 3 µm fibre laser diode-pumped at 975 nm

    NARCIS (Netherlands)

    Jackson, S.D.; King, T.A.; Pollnau, Markus


    Efficient CW operation of a 2.71 um Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of <

  17. Manufacturing Technology Development of Advanced Components for High Power Solid State Lasers (United States)


    controlled KTiOP04 optical parametric oscillator," Opt. Lett. 32, 274-276 (2007). [2] P. B. Phua, B. S. Tan, R. F. Wu, K. S. Lai, L. Chia , E. Lau...ultrafast seed laser, 1st amplifier stage, 2 a amplifier stage, and beam characterization equipment. 4. Ti:Sapphire Laser Oscillator, Pre-Amplifier, and

  18. Optical systems for high-power laser applications: principles and design aspects

    NARCIS (Netherlands)

    Beckmann, L.H.J.F.; Ehrlichmann, D.


    Starting from the optical properties of laser beams, the requirements of optical systems for manipulating laser radiation in industrial applications are derived. The relevant parameters, relations to the diffraction limit and the state-of-the-art design techniques are discussed. The three important

  19. A comparative investigation of the efficacy of CO2 and high power diode lasers for the forming of EN3 mild steel sheets


    Lawrence, Jonathan


    A comparative investigation of the effectiveness of a high power diode laser (HPDL) and a CO2 laser for the forming of thin section EN3 mild steel sheet has been conducted. The buckling mechanism was identified as the laser forming mechanism responsible for the induced bending. For both lasers it was found that the induced bending angles increased with an increasing number of irradiations and high laser powers, whilst decreasing as the traverse speed was increased. Also, it was apparent from ...

  20. Nanoparticle doping for high power fiber lasers at eye-safer wavelengths. (United States)

    Baker, Colin C; Friebele, E Joseph; Burdett, Ashley A; Rhonehouse, Daniel L; Fontana, Jake; Kim, Woohong; Bowman, Steven R; Shaw, L Brandon; Sanghera, Jasbinder; Zhang, Jun; Pattnaik, Radha; Dubinskii, Mark; Ballato, John; Kucera, Courtney; Vargas, Amber; Hemming, Alexander; Simakov, Nikita; Haub, John


    A nanoparticle (NP) doping technique was developed for fabricating erbium (Er)- and holmium (Ho)-doped silica-based optical fibers for high energy lasers. Slope efficiencies in excess of 74% were realized for Er NP doping in a single mode fiber based master oscillator power amplifier (MOPA) and 53% with multi-Watt-level output in a resonantly cladding-pumped power oscillator laser configuration based on a double-clad fiber. Cores comprising Ho doped LaF3 and Lu2O3 nanoparticles exhibited slope efficiencies as high as 85% at 2.09 µm in a laser configuration. To the best of the authors' knowledge, this is the first report of a holmium nanoparticle doped fiber laser as well as the highest efficiency and power output reported from an erbium nanoparticle doped fiber laser.