WorldWideScience

Sample records for bistable laser diodes

  1. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    Science.gov (United States)

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  2. Bistable optical devices with laser diodes coupled to absorbers of narrow spectral bandwidth.

    Science.gov (United States)

    Maeda, Y

    1994-06-20

    An optical signal inverter was demonstrated with a combination of the following two effects: One is the decrease of the transmission of an Er-doped YAG crystal with increasing red shift of a laser diode resulting from an increase in the injection current, and the other is a negative nonlinear absorption in which the transmission decreases inversely with increasing laser intensity. Because a hysteresis characteristic exists in the relationship between the wavelength and the injection current of the laser diode, an optical bistability was observed in this system.

  3. Bistable output from a coupled-resonator vertical-cavity laser diode

    International Nuclear Information System (INIS)

    Fischer, A. J.; Choquette, K. D.; Chow, W. W.; Allerman, A. A.; Geib, K.

    2000-01-01

    We report a monolithic coupled-resonator vertical-cavity laser with an ion-implanted top cavity and a selectively oxidized bottom cavity which exhibits bistable behavior in the light output versus injection current. Large bistability regions over current ranges as wide as 18 mA have been observed with on/off contrast ratios of greater than 20 dB. The position and width of the bistability region can be varied by changing the bias to the top cavity. Switching between on and off states can be accomplished with changes as small as 250 μW to the electrical power applied to the top cavity. The bistable behavior is the response of the nonlinear susceptibility in the top cavity to the changes in the bottom intracavity laser intensity as the bottom cavity reaches the thermal rollover point

  4. Bistable Output from a Coupled-Resonator Vertical-Cavity Laser Diode

    Energy Technology Data Exchange (ETDEWEB)

    FISCHER,ARTHUR J.; CHOQUETTE,KENT D.; CHOW,WENG W.; ALLERMAN,ANDREW A.; GEIB,KENT M.

    2000-07-20

    The authors report a monolithic coupled-resonator vertical-cavity laser with an ion-implanted top cavity and a selectively oxidized bottom cavity which exhibits bistable behavior in the light output versus injection current. Large bistability regions over current ranges as wide as 18 mA have been observed with on/off contrast ratios of greater than 20 dB. The position and width of the bistability region can be varied by changing the bias to the top cavity. Switching between on and off states can be accomplished with changes as small as 250 {micro}W to the electrical power applied to the top cavity. Theoretical analysis suggests that the bistable behavior is the response of the nonlinear susceptibility in the top cavity to the changes in the bottom intracavity laser intensity as the bottom cavity reaches the thermal rollover point.

  5. Optical bistability in side-mode injection locked dual-mode Fabry-Pérot laser diode

    Directory of Open Access Journals (Sweden)

    Jian Wei Wu

    2013-08-01

    Full Text Available In this paper, optical bistability characteristics are demonstrated experimentally based on a dual-mode laser system comprising a multi-mode Fabry-Pérot laser diode (MMFP-LD and a built-in feedback cavity formed by a fiber facet. The results show that two lasing modes with frequency separation of ∼0.58 THz and comparable peak powers can be achieved by judicious adjustment of the bias current and the operating temperature of the laser chip, which has a peak fluctuation of less than ∼1 dBm over a measurement period of one hour. A combination of appropriate external injection power and wavelength detuning can result in remarkable optical bistability in two oscillation modes, in which the resulting contrast ratio between the unlocked and locked states can be up to 30 dB, and the corresponding hysteresis loop width can be changed by controlling the side-mode injection power and the wavelength detuning.

  6. High-Speed and Low-Energy Flip-Flop Operation of Asymmetric Active-Multimode Interferometer Bi-Stable Laser Diodes

    DEFF Research Database (Denmark)

    Jiang, Haisong; Chaen, Yutaka; Hagio, Takuma

    2011-01-01

    High-speed (121/25 ps rise/fall time) and low-switching energy (7.1 and 3.4 fJ) alloptical flip-flop operation of single-wavelength high-mesa asymmetric active-MMI bi-stable laser diodes is demonstrated for the first time using 25 ps long switching pulses.......High-speed (121/25 ps rise/fall time) and low-switching energy (7.1 and 3.4 fJ) alloptical flip-flop operation of single-wavelength high-mesa asymmetric active-MMI bi-stable laser diodes is demonstrated for the first time using 25 ps long switching pulses....

  7. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  8. Ultra-Fast All-Optical Self-Aware Protection Switching Based on a Bistable Laser Diode

    DEFF Research Database (Denmark)

    An, Yi; Vukovic, Dragana; Lorences Riesgo, Abel

    2014-01-01

    We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps....

  9. Bistability in a laser with injected signal

    International Nuclear Information System (INIS)

    Dorobantu, I.A.; Vlad, V.I.; Ursu, I.

    1987-04-01

    A unified description of bistability is given in free running lasers, optical bistable devices, ring lasers and lasers with an injected signal (LIS). A general review of laser instabilities is also presented in the frame of the theory of elementary catastrophes, emphasizing the apparence of higher order catastrophes in the case of a LIS suggesting thus a possibility to devise from first principles the whole hierarchy of laser instabilities. Experimental results on the bistability in the polarisation of LIS are also discussed. (authors)

  10. Bistable polarization switching in a continuous wave ruby laser

    Science.gov (United States)

    Lawandy, N. M.; Afzal, R. Sohrab

    1988-01-01

    Bistability in the output power, polarization state, and mode volume of an argon-ion laser pumped single mode ruby laser at 6943 A has been observed. The laser operates in a radially confined mode which exhibits hysteresis and bistability only when the pump polarization is parallel to the c-axis.

  11. Diode laser pumping

    International Nuclear Information System (INIS)

    Skagerlund, L.E.

    1975-01-01

    A diode laser is pumped or pulsed by a repeated capacitive discharge. A capacitor is periodically charged from a dc voltage source via a transformer, the capacitor being discharged through the diode laser via a controlled switching means after one or more charging periods. During a first interval of each charging period the transformer, while unloaded, stores a specific amount of energy supplied from the dc voltage source. During a subsequent interval of the charging period said specific amount of energy is transmitted from the transformer to the capacitor. The discharging of the capacitor takes place during a first interval of a charging period. (auth)

  12. Infrared diode laser spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Cihelka, Jaroslav; Matulková, Irena

    2010-01-01

    Roč. 18, č. 4 (2010), s. 408-420 ISSN 1230-3402 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503 Keywords : FTIR spectroscopy * absorption spectroscopy * laser diodes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.027, year: 2010

  13. Diode-pumped neodymium lasers

    Science.gov (United States)

    Albers, Peter

    1990-08-01

    Since the invention of diode lasers in the early 1960's there had been continuous investigations in laser diode pumped solid state lasers as has been reviewed in detail by a number of papers ( see e.g. [1] ). There are two main advantages of using diode lasers instead of flashlaraps as a pump source for solid state lasers: First the emission of the diode lasers matches well with the absorption bands of several Rare Earth ions that are doped in laser crystals ( mainly Nd3+, but also Er3, Tm3, Dy3', and others ) . This summary will report only about diode lasers at a wavelength of around BlOnm, which fits to an absorptionband of Nd3t Second diode lasers provide the possibility of longitudinally pumped configurations and therefore an excellent mode matching with the solid state laser mode. For both reasons the efficiency of a diode laser puniped solid state laser is nuch higher than of a flashlamp pumped one. Since the early 1980's a much wider interest in diode laser pumped solid state lasers arose. It was stimulated by the improved performance of the new generation of diode lasers in terms of reliability , operational lifetime and output power [21. Two important steps in direction to the diode lasers at present time were the developments of double hetero (DH) structure- and graded index separate confinement hetero (GrInSCH) structurediode lasers. In the same way the development of new production techniques were necessary to ensure the reliability of the diode lasers. Starting with the liquid phase epitaxy (LPE) the (GaAl)As structures are now grown by the molecular beam epitaxy (MBE), mainly used for very high precision laboratory investigations, and metal organic chemical vapour deposition (MOCVD), mainly used for commercial production. As a first commercial product SDL introduced a 100mW array in 1984. Since then the output power of the commercially available diode lasers increased by two orders of magnitude to lOW. These diode lasers are multi stripe bar arrays

  14. Atomic spectroscopy with diode lasers

    International Nuclear Information System (INIS)

    Tino, G.M.

    1994-01-01

    Some applications of semiconductor diode lasers in atomic spectroscopy are discussed by describing different experiments performed with lasers emitting in the visible and in the near-infrared region. I illustrate the results obtained in the investigation of near-infrared transitions of atomic oxygen and of the visible intercombination line of strontium. I also describe how two offset-frequency-locked diode lasers can be used to excite velocity selective Raman transitions in Cs. I discuss the spectral resolution, the accuracy of frequency measurements, and the detection sensitivity achievable with diode lasers. (orig.)

  15. Enhanced vbasis laser diode package

    Science.gov (United States)

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  16. Laser Diode Beam Basics, Manipulations and Characterizations

    CERN Document Server

    Sun, Haiyin

    2012-01-01

    Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations. There are some internet resources dealing with laser diode beams. However, these internet resources have not covered enough materials with enough details on laser diode beam manipulations and characterizations. A technical book concentrated on laser diode beam manipulations and characterizations can fit in to the open and provide useful information to laser diode users. Laser Diode Beam Basics, Manipulations and  Characterizations is concentrated on the very practical side of the subject, it only discusses the basic physics and mathematics that are necessary for the readers in order...

  17. Air-stable memory array of bistable rectifying diodes based on ferroelectric-semiconductor polymer blends

    Science.gov (United States)

    Kumar, Manasvi; Sharifi Dehsari, Hamed; Anwar, Saleem; Asadi, Kamal

    2018-03-01

    Organic bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers have emerged as promising candidates for non-volatile information storage for low-cost solution processable electronics. One of the bottlenecks impeding upscaling is stability and reliable operation of the array in air. Here, we present a memory array fabricated with an air-stable amine-based semiconducting polymer. Memory diode fabrication and full electrical characterizations were carried out in atmospheric conditions (23 °C and 45% relative humidity). The memory diodes showed on/off ratios greater than 100 and further exhibited robust and stable performance upon continuous write-read-erase-read cycles. Moreover, we demonstrate a 4-bit memory array that is free from cross-talk with a shelf-life of several months. Demonstration of the stability and reliable air operation further strengthens the feasibility of the resistance switching in ferroelectric memory diodes for low-cost applications.

  18. Laser scanning laser diode photoacoustic microscopy system.

    Science.gov (United States)

    Erfanzadeh, Mohsen; Kumavor, Patrick D; Zhu, Quing

    2018-03-01

    The development of low-cost and fast photoacoustic microscopy systems enhances the clinical applicability of photoacoustic imaging systems. To this end, we present a laser scanning laser diode-based photoacoustic microscopy system. In this system, a 905 nm, 325 W maximum output peak power pulsed laser diode with 50 ns pulsewidth is utilized as the light source. A combination of aspheric and cylindrical lenses is used for collimation of the laser diode beam. Two galvanometer scanning mirrors steer the beam across a focusing aspheric lens. The lateral resolution of the system was measured to be ∼21 μm using edge spread function estimation. No averaging was performed during data acquisition. The imaging speed is ∼370 A-lines per second. Photoacoustic microscopy images of human hairs, ex vivo mouse ear, and ex vivo porcine ovary are presented to demonstrate the feasibility and potentials of the proposed system.

  19. Bistability and self-oscillations effects in a polariton-laser semiconductor microcavity

    International Nuclear Information System (INIS)

    Cotta, E A; Matinaga, F M

    2007-01-01

    We report an experimental observation of polaritonic optical bistability of the laser emission in a planar semiconductor microcavity with a 100 0 A GaAs single quantum well in the strong-coupling regime. The bistability curves show crossings that indicate a competition between a Kerr-like effect induced by the polariton population and thermal effects. Associated with the bistability, laser-like emission occurs at the bare cavity mode

  20. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)

    2000-04-01

    Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)

  1. Laser materials processing with diode lasers

    OpenAIRE

    Li, Lin; Lawrence, Jonathan; Spencer, Julian T.

    1996-01-01

    Laser materials processing is currently dominated by CO2, Nd-YAG and Excimer lasers. Continuous advances in semiconductor laser technology over the last decade have increased the average power output of the devices annualy by two fold, resulting in the commercial availability of the diode lasers today with delivery output powers in excess of 60W in CW mode and 5kW in qasi-CW mode. The advantages of compactness, high reliability, high efficiency and potential low cost, due to the mass producti...

  2. Stopping atoms with diode lasers

    International Nuclear Information System (INIS)

    Watts, R.N.; Wieman, C.E.

    1986-01-01

    The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

  3. Resonant activation in bistable semiconductor lasers

    International Nuclear Information System (INIS)

    Lepri, Stefano; Giacomelli, Giovanni

    2007-01-01

    We theoretically investigate the possibility of observing resonant activation in the hopping dynamics of two-mode semiconductor lasers. We present a series of simulations of a rate-equation model under random and periodic modulation of the bias current. In both cases, for an optimal choice of the modulation time scale, the hopping times between the stable lasing modes attain a minimum. The simulation data are understood by means of an effective one-dimensional Langevin equation with multiplicative fluctuations. Our conclusions apply to both edge-emitting and vertical cavity lasers, thus opening the way to several experimental tests in such optical systems

  4. Blue-emitting laser diodes

    Science.gov (United States)

    Nakano, K.; Ishibashi, A.

    This paper reviews the recent results of blue-emitting laser diodes. These devices are based on ZnMgSSe alloy II-VI semiconductors. Recently we have achieved room temperature continuous-wave operation of ZnMgSSe blue lasers for the first time. ZnMgSSe alloys offer a wide range of band-gap energy from 2.8 to 4.5 eV, while maintaining lattice matching to GaAs substrates. These characteristics make ZnMgSSe suitable for cladding layers of blue lasers. In this article, the feasibilities of ZnMgSSe will be reviewed. The laser structures and characteristics will be also mentioned.

  5. Novel diode laser system for photodynamic therapy

    DEFF Research Database (Denmark)

    Samsøe, E.; Petersen, P.M.; Andersen, Peter E.

    2001-01-01

    In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system...... is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through tile fiber scales linearly with the power of the laser diode. which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50...

  6. Bistable laser device with multiple coupled active vertical-cavity resonators

    Science.gov (United States)

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-08-19

    A new class of bistable coupled-resonator vertical-cavity semiconductor laser devices has been developed. These bistable laser devices can be switched, either electrically or optically, between lasing and non-lasing states. A switching signal with a power of a fraction of a milliwatt can change the laser output of such a device by a factor of a hundred, thereby enabling a range of optical switching and data encoding applications.

  7. Laser diode package with enhanced cooling

    Science.gov (United States)

    Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

    2011-09-13

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  8. Diode Laser Ear Piercing: A Novel Technique.

    Science.gov (United States)

    Suseela, Bibilash Babu; Babu, Preethitha; Chittoria, Ravi Kumar; Mohapatra, Devi Prasad

    2016-01-01

    Earlobe piercing is a common office room procedure done by a plastic surgeon. Various methods of ear piercing have been described. In this article, we describe a novel method of laser ear piercing using the diode laser. An 18-year-old female patient underwent an ear piercing using a diode laser with a power of 2.0 W in continuous mode after topical local anaesthetic and pre-cooling. The diode laser was fast, safe, easy to use and highly effective way of ear piercing. The advantages we noticed while using the diode laser over conventional methods were more precision, minimal trauma with less chances of hypertrophy and keloids, no bleeding with coagulation effect of laser, less time taken compared to conventional method and less chance of infection due to thermal heat effect of laser.

  9. Improved Thermoelectrically Cooled Laser-Diode Assemblies

    Science.gov (United States)

    Glesne, Thomas R.; Schwemmer, Geary K.; Famiglietti, Joe

    1994-01-01

    Cooling decreases wavelength and increases efficiency and lifetime. Two improved thermoelectrically cooled laser-diode assemblies incorporate commercial laser diodes providing combination of both high wavelength stability and broad wavelength tuning which are broadly tunable, highly stable devices for injection seeding of pulsed, high-power tunable alexandrite lasers used in lidar remote sensing of water vapor at wavelengths in vicinity of 727 nanometers. Provide temperature control needed to take advantage of tunability of commercial AlGaAs laser diodes in present injection-seeding application.

  10. Optical bistability in the oscillation of an inhomogeneously broadened quasi-three-level laser

    International Nuclear Information System (INIS)

    Liu, Junhai; Tian, Xueping

    2013-01-01

    A theoretical modeling analysis is presented to study the optical bistability exhibited in the oscillation of an inhomogeneously broadened quasi-three-level laser. All the major characteristics of optical bistability depend on two normalized parameters, f and x a , which are defined by f = I sat,a /I sat,m and x a = 2α a0 p a /δ and are related to measurable properties of the laser medium. In comparison with the case of a homogeneously broadened laser, the essential condition for the occurrence of such bistability, f a /(x a + 1), turns out to be the same, whereas the intensities at the up- and down-thresholds are substantially increased and the bistability range is reduced. (paper)

  11. Laterally injected light-emitting diode and laser diode

    Science.gov (United States)

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  12. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    Science.gov (United States)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  13. Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit

    OpenAIRE

    Cappuccio, Joseph C., Jr.

    1988-01-01

    Approved for public release; distribution is unlimited This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse m...

  14. Tapered diode laser pumped 946 nm Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2009-01-01

    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  15. NAMMA DIODE LASER HYGROMETER (DLH) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Diode Laser Hygrometer (DLH), a near-infrared spectrometer operating from aircraft platforms, was developed by NASA's Langley and Ames Research Centers. It...

  16. NAMMA DIODE LASER HYGROMETER (DLH) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Diode Laser Hygrometer (DLH) dataset uses the DLH, a near-infrared spectrometer operating from aircraft platforms, was developed by NASA's Langley and Ames...

  17. Next generation diode lasers with enhanced brightness

    Science.gov (United States)

    Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

    2018-02-01

    High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

  18. Bistability of self-modulation oscillations in an autonomous solid-state ring laser

    International Nuclear Information System (INIS)

    Dudetskii, V Yu

    2013-01-01

    Bistable self-modulation regimes of generation for a ring YAG : Nd chip laser with the counterpropagating waves asymmetrically coupled via backward scattering are simulated numerically. Two branches of bistable self-modulation regimes of generation are found in the domain of the parametric resonance between the selfmodulation and relaxation oscillations. The self-modulation regimes observed in earlier experiments pertain to only one of the branches. Possible reasons for such a discrepancy are considered, related to the influence of technical and natural noise on the dynamics of solid-state ring lasers. (control of laser radiation parameters)

  19. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

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

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications....

  20. Bistability and hysteresis in the emergence of pulses in microstrip Gunn-diode circuits

    Energy Technology Data Exchange (ETDEWEB)

    Yurchenko, V. B., E-mail: v.yurchenko@nuim.ie [O. Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Proskura St., Kharkiv 61085 (Ukraine); Electrical and Electronic Engineering Department, Gazi University, Celal Bayar Bulvari, Ankara 06570 (Turkey); Yurchenko, L. V. [O. Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Proskura St., Kharkiv 61085 (Ukraine)

    2014-12-15

    We develop time-domain simulations of microwave and THz radiation sources built as arrays of active devices when the radiation wavelength is small as compared to spacing between electronic components. We pursue an approach when the system is represented by equations with time-delay feedback that could generate chaos and other forms of complicated dynamics. The approach simplifies simulations of ultra-wideband effects and exceeds capabilities of frequency-domain methods. As a model case, we simulated a microstrip circuit with Gunn diode and a remote resonator emitting the radiation towards infinity. We observed the emergence of either the continuous waves or the trains of high-frequency pulses depending on the bias conditions. We found bistability and hysteresis in the onset of different oscillation modes that depends on the way of driving the bias voltage into the domain of instability of the given system. The results would allow one to improve the design of THz radiation sources with time-delay coupling between components.

  1. Bistability and hysteresis in the emergence of pulses in microstrip Gunn-diode circuits

    Directory of Open Access Journals (Sweden)

    V. B. Yurchenko

    2014-12-01

    Full Text Available We develop time-domain simulations of microwave and THz radiation sources built as arrays of active devices when the radiation wavelength is small as compared to spacing between electronic components. We pursue an approach when the system is represented by equations with time-delay feedback that could generate chaos and other forms of complicated dynamics. The approach simplifies simulations of ultra-wideband effects and exceeds capabilities of frequency-domain methods. As a model case, we simulated a microstrip circuit with Gunn diode and a remote resonator emitting the radiation towards infinity. We observed the emergence of either the continuous waves or the trains of high-frequency pulses depending on the bias conditions. We found bistability and hysteresis in the onset of different oscillation modes that depends on the way of driving the bias voltage into the domain of instability of the given system. The results would allow one to improve the design of THz radiation sources with time-delay coupling between components.

  2. Diode-side-pumped Alexandrite slab lasers.

    Science.gov (United States)

    Damzen, M J; Thomas, G M; Minassian, A

    2017-05-15

    We present the investigation of diode-side-pumping of Alexandrite slab lasers in a range of designs using linear cavity and grazing-incidence bounce cavity configurations. An Alexandrite slab laser cavity with double-pass side pumping produces 23.4 mJ free-running energy at 100 Hz rate with slope efficiency ~40% with respect to absorbed pump energy. In a slab laser with single-bounce geometry output power of 12.2 W is produced, and in a double-bounce configuration 6.5 W multimode and 4.5 W output in TEM 00 mode is produced. These first results of slab laser and amplifier designs in this paper highlight some of the potential strategies for power and energy scaling of Alexandrite using diode-side-pumped Alexandrite slab architectures with future availability of higher power red diode pumping.

  3. Ultrafast photoconductor detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davis, B.A.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.

    1987-01-01

    We report the results of an experiment in which we used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When we irradiated the neutron-damaged Cr-doped GaAs detector with 17-MeV electron beams, the temporal response was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. We are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  4. Ultrafast photoconductive detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.; Davis, B.A.

    1987-01-01

    The authors report the results of an experiment in which they used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When they irradiated the neutron-damaged Cr-doped Ga/As detector with 17-MeV electron beams, the temporal response of was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. They are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  5. The transformation of optical bistability effect and of generated pulses in operation of a DFB laser with two sections

    International Nuclear Information System (INIS)

    Nguyen Van Phu; Dinh Van Hoang

    2005-01-01

    In this paper is presented the transformation of characteristics of optical bistability effect and of generated pulses in operation of a DFB laser with two sections. By solving the rate equations describing the operation of this laser the appearance of optical bistability effect in stationary regime and of short pulses in transient regime is obtained. With the variation of dynamical laser parameter we can evaluate the transformation indicated above. The method of examination used here is simple for determining the influence of any dynamical laser parameter on characteristics of optical bistability effect and generated pulses. (author)

  6. Stirling-Cycle Cooling For Tunable Diode Laser

    Science.gov (United States)

    Durso, Santo S.; May, Randy D.; Tuchscherer, Matthew A.; Webster, Christopher R.

    1991-01-01

    Miniature Stirling-cycle cooler effective in continously cooling PbSnTe tunable diode laser to stable operating temperature near 80 K. Simplifies laboratory diode-laser spectroscopy and instruments for use aboard aircraft and balloons.

  7. High power diode lasers converted to the visible

    DEFF Research Database (Denmark)

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

    2017-01-01

    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....

  8. The Beam Characteristics of High Power Diode Laser Stack

    Science.gov (United States)

    Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

    2018-03-01

    Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

  9. Diode laser prostatectomy (VLAP): initial canine evaluation

    Science.gov (United States)

    Kopchok, George E.; Verbin, Chris; Ayres, Bruce; Peng, Shi-Kaung; White, Rodney A.

    1995-05-01

    This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

  10. Microring Diode Laser for THz Generation

    DEFF Research Database (Denmark)

    Mariani, S.; Andronico, A.; Favero, I.

    2013-01-01

    We report on the modeling and optical characterization of AlGaAs/InAs quantum-dot microring diode lasers designed for terahertz (THz) difference frequency generation (DFG) between two whispering gallery modes (WGMs) around 1.3 $\\mu$m. In order to investigate the spectral features of this active...

  11. Outcome of Diode Laser Cyclophotocoagulation in Neovascular ...

    African Journals Online (AJOL)

    Aim: To find out the short-term outcome of ciliary ablation with diode laser contact cyclophotocoagulation in Nigerians with neovascular glaucoma. Methods: The study is a retrospective, non-comparative, interventional case series. Demographic data, ocular and systemic history were obtained. Clinical examination included ...

  12. Fast all-optical flip-flop based on a single distributed feedback laser diode.

    Science.gov (United States)

    Huybrechts, Koen; Morthier, Geert; Baets, Roel

    2008-07-21

    Since there is an increasing demand for fast networks and switches, the electronic data processing imposes a severe bottleneck and all-optical processing techniques will be required in the future. All-optical flip-flops are one of the key components because they can act as temporary memory elements. Several designs have already been demonstrated but they are often relatively slow or complex to fabricate. We demonstrate experimentally fast flip-flop operation in a single DFB laser diode which is one of the standard elements in today's telecommunication industry. Injecting continuous wave light in the laser diode, a bistability is obtained due to the spatial hole burning effect. We can switch between the two states by using pulses with energies below 200 fJ resulting in flip-flop operation with switching times below 75 ps and repetition rates of up to 2 GHz.

  13. Compact green-diode-based lasers for biophotonic bioimaging

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Petersen, Paul Michael

    2014-01-01

    Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers.......Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers....

  14. Controllable optical bistability in photonic-crystal one-atom laser

    International Nuclear Information System (INIS)

    Guo Xiaoyong; Lue Shuchen

    2009-01-01

    We investigate the property of optical bistability in a photonic-crystal one-atom laser when nonlinear microcavity is present. The physical system consists of a coherently driven two-level light emitter strongly coupled to a high-quality microcavity which is embedded within a photonic crystal and another coherent probing field which has incident into the microcavity. In our case, the microcavity is fabricated by nonlinear material and placed as an impurity in photonic crystal. This study reveals that such a system can exhibit optical bistability. The dependence of threshold value and hysteresis loop on the photonic band gap of the photonic crystal, driving field Rabi frequency and dephasing processes, are studied. Our results clearly illustrate the ability to control optical bistability through suitable photonic-crystal architectures and external coherent driving field, and this study suggests that in a photonic-crystal nonlinear microcavity, the one-atom laser acts as an effective controllable bistable device in the design of all-light digital computing systems in the near future.

  15. Temperature persistent bistability and threshold switching in a single barrier heterostructure hot-electron diode

    DEFF Research Database (Denmark)

    Stasch, R.; Hey, R.; Asche, M.

    1996-01-01

    Bistable current–voltage characteristics caused by competition of tunneling through and field-enhanced thermionic emission across a single barrier are investigated in an n–-GaAs/Al0.34Ga0.66As/n+-GaAs structure. The S-shaped part of the characteristic persists in the whole temperature regime...

  16. Diode-laser-illuminated automotive lamp systems

    Science.gov (United States)

    Marinelli, Michael A.; Remillard, Jeffrey T.

    1998-05-01

    We have utilized the high brightness of state-of-the-art diode laser sources, and a variety of emerging optical technologies to develop a new class of thin, uniquely styled automotive brake and signal lamps. Using optics based on thin (5 mm) plastic sheets, these lamps provide appearance and functional advantages not attainable with traditional automotive lighting systems. The light is coupled into the sheets using a 1 mm diameter glass fiber, and manipulated using refraction and reflection from edges, surfaces, and shaped cut-outs. Light can be extracted with an efficiency of approximately 50% and formed into a luminance distribution that meets the Society of Automotive Engineers (SAE) photometric requirements. Prototype lamps using these optics have been constructed and are less than one inch in thickness. Thin lamps reduce sheet metal costs, complexity, material usage, weight, and allow for increased trunk volume. In addition, these optics enhance lamp design flexibility. When the lamps are not energized, they can appear body colored, and when lighted, the brightness distribution across the lamp can be uniform or structured. A diode laser based brake lamp consumes seven times less electrical power than one using an incandescent source and has instant on capability. Also, diode lasers have the potential to be 10-year/150,000 mile light sources.

  17. Bistability and low-frequency fluctuations in semiconductor lasers with optical feedback: a theoretical analysis

    DEFF Research Database (Denmark)

    Mørk, Jesper; Tromborg, Bjarne; Christiansen, Peter Leth

    1988-01-01

    Near-threshold operation of a semiconductor laser exposed to moderate optical feedback may lead to low-frequency fluctuations. In the same region, a kink is observed in the light-current characteristic. Here it is demonstrated that these nonlinear phenomena are predicted by a noise driven multimode...... traveling-wave model. The dynamics of the low-frequency fluctuations are explained qualitatively in terms of bistability through an iterative description...

  18. High-power laser diodes at various wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Emanuel, M.A.

    1997-02-19

    High power laser diodes at various wavelengths are described. First, performance and reliability of an optimized large transverse mode diode structure at 808 and 941 nm are presented. Next, data are presented on a 9.5 kW peak power array at 900 nm having a narrow emission bandwidth suitable for pumping Yb:S-FAP laser materials. Finally, results on a fiber-coupled laser diode array at {approx}730 nm are presented.

  19. Noise equivalent circuit of a semiconductor laser diode

    OpenAIRE

    Harder, Christoph; Katz, Joseph; Margalit, S.; Shacham, J.; Yariv, A.

    1982-01-01

    The noise equivalent circuit of a semiconductor laser diode is derived from the rate equations including Langevin noise sources. This equivalent circuit allows a straightforward calculation of the noise and modulation characteristics of a laser diode combined with electronic components. The intrinsic junction voltage noise spectrum and the light intensity fluctuation of a current driven laser diode are calculated as a function of bias current and frequency.

  20. Diode lasers optimized in brightness for fiber laser pumping

    Science.gov (United States)

    Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

    2018-02-01

    In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

  1. Polarization methods for diode laser excitation of solid state lasers

    Science.gov (United States)

    Holtom, Gary R.

    2008-11-25

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. A Yb-doped gain medium can be used that absorbs light having a first polarization and emits light having a second polarization. Using such pumping with laser cavity dispersion control, pulse durations of less than 100 fs can be achieved.

  2. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    International Nuclear Information System (INIS)

    Deri, R.J.

    2011-01-01

    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a ∼ 200 (micro)s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  3. High power diode laser remelting of metals

    International Nuclear Information System (INIS)

    Chmelickova, H; Tomastik, J; Ctvrtlik, R; Supik, J; Nemecek, S; Misek, M

    2014-01-01

    This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.

  4. Linear diode laser bar optical stretchers for cell deformation

    Science.gov (United States)

    Sraj, Ihab; Marr, David W.M.; Eggleton, Charles D.

    2010-01-01

    To investigate the use of linear diode laser bars to optically stretch cells and measure their mechanical properties, we present numerical simulations using the immersed boundary method (IBM) coupled with classic ray optics. Cells are considered as three-dimensional (3D) spherical elastic capsules immersed in a fluid subjected to both optical and hydrodynamic forces in a periodic domain. We simulate cell deformation induced by both single and dual diode laser bar configurations and show that a single diode laser bar induces significant stretching but also induces cell translation of speed < 10 µm/sec for applied 6.6 mW/µm power in unconfined systems. The dual diode laser bar configuration, however, can be used to both stretch and optically trap cells at a fixed position. The net cell deformation was found to be a function of the total laser power and not the power distribution between single or dual diode laser bar configurations. PMID:21258483

  5. Method for partially coating laser diode facets

    Science.gov (United States)

    Dholakia, Anil R. (Inventor)

    1990-01-01

    Bars of integral laser diode devices cleaved from a wafer are placed with their p regions abutting and n regions abutting. A thin BeCu mask having alternate openings and strips of the same width as the end facets is used to mask the n region interfaces so that multiple bars can be partially coated over their exposed p regions with a reflective or partial reflective coating. The partial coating permits identification of the emitting facet from the fully coated back facet during a later device mounting procedure.

  6. Spectral control of diode lasers using external waveguide circuits

    NARCIS (Netherlands)

    Oldenbeuving, Ruud

    2013-01-01

    We investigated spectral control of diode lasers using external waveguide circuits. The purpose of this work is to investigate such external control for providing a new class of diode lasers with technologically interesting properties, such as a narrow spectral bandwidth and spectrally tunable

  7. Diode lasers for interstitial laser coagulation of the prostate

    Science.gov (United States)

    Muschter, Rolf; Perlmutter, Aaron P.; Anson, K.; Jahnen, P.; Vargas Stuve, Juan C.; Razvi, Hassan A.; Sroka, Ronald; Hofstetter, Alfons G.; Vaughan, Darracott E., Jr.

    1995-05-01

    The concept of interstitial laser coagulation (ILC) of the prostate is the generation of intraprostatic lesions of large volumes, which secondarily are resorbed. In previously published experimental and clinical studies Nd:YAG lasers in combination with specially designed light guides were used. The aim of this study was to examine the suitability of diode lasers to be used in ILC. Diode lasers of various wavelengths (805 nm, 830 nm, 950 nm and 980 nm) with different interstitial applicators (predominantly diffusor tips) were tested in vitro (potatoes, turkey muscle, porcine liver) and in vivo (canine prostate). In vitro experiments were done with various powers and radiation times in order to evaluate the maximum lesion size achievable without tissue carbonization. This depended on the length of the applicator and could measure more than 20 mm. To get large lesion volumes with short radiation times, but to avoid charring, in vivo graded powers were favorable. These were optimized for some systems. In the canine prostate, lesion diameters of up to 15 mm were achieved. For clinical use, interstitial applicators were inserted into the bulky BPH transurethrally through a cystoscope under direct vision, either directly or aided by an introducer system. The number of fiber placements depended on the size and configuration of the gland and varied between 3 and 16. With the 980 nm diode laser and an applicator with conical beam pattern, irradiation was performed for 3 minutes per fiber placement using stepwise reduced power (20 W for 30 s, 15 W for 30 s, 10 W for 30 s and 7 W for 90 s). With the 830 nm diode laser and diffusor tip, the initial power of 10 W was reduced to 5 W within 4 minutes total radiation time. From 1993, 19 patients were treated with diode lasers (830 and 980 nm). Three months follow-up in 15 patients treated with 830 nm showed an AUA-score change from 18.9 to 5.9 and a peak flow rate change from 7.8 to 15.2 ml/s.

  8. The theory of stability, bistability, and instability in three-mode class-A lasers

    International Nuclear Information System (INIS)

    Jahanpanah, J; Rahdar, A A

    2014-01-01

    Instability is an inevitable and common problem in all different kinds of lasers when they are oscillating in both single-and multi-mode states. Here, the stability conditions are investigated for a three-mode class-A laser. A set of linear equations is derived for the stable oscillation of the cavity central mode together with its left and right adjacent longitudinal modes. The coefficient determinant of stability equations is Hermitian and equal to zero for the roots of two diagonal arrays. In other words, the novelty of our work is to expand the stability coefficient determinant in terms of main diagonal arrays rather than for one row or one column. These diagonal roots lead to two lower and upper boundary curves in the form of a bifurcation. The lower boundary curve mimics the single-mode laser and delimits the instability region (with no above-threshold oscillating mode) from the bistability region (with two above-threshold oscillating modes). The upper boundary curve mimics the two-mode laser and delimits the bistability region from the stability region, in which all three-longitudinal modes are simultaneously oscillating in the above-threshold state. (paper)

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

    DEFF Research Database (Denmark)

    Müller, André

    spectroscopy and imaging, and fluorescence measurements. A major challenge in diode laser technology is to obtain high-power laser emission at wavelengths green spectral range is of high importance, for example, in dermatology or for direct pumping of ultrashort pulsed lasers...... 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...... output power of frequency doubled single emitters is limited by thermal effects potentially resulting in laser degradation and failure. In this work new concepts for power scaling of visible diode laser systems are introduced that help to overcome current limitations and enhance the application potential...

  10. A practical guide to handling laser diode beams

    CERN Document Server

    Sun, Haiyin

    2015-01-01

    This book offers the reader a practical guide to the control and characterization of laser diode beams.  Laser diodes are the most widely used lasers, accounting for 50% of the global laser market.  Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  The core of the book is concerned with laser diode beam manipulations: collimating and focusing, circularization and astigmatism correction, coupling into a single mode optical fiber, diffractive optics and beam shaping, and manipulation of multi transverse mode beams.  The final chapter of the book covers beam characterization methods, describing the measurement of spatial and spectral properties, including wavelength and linewidth meas...

  11. Photoluminescence excitation measurements using pressure-tuned laser diodes

    Science.gov (United States)

    Bercha, Artem; Ivonyak, Yurii; Medryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-06-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available.

  12. Photoluminescence excitation measurements using pressure-tuned laser diodes

    International Nuclear Information System (INIS)

    Bercha, Artem; Ivonyak, Yurii; Mędryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-01-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available

  13. Computer-Assisted Experiments with a Laser Diode

    Science.gov (United States)

    Kraftmakher, Yaakov

    2011-01-01

    A laser diode from an inexpensive laser pen (laser pointer) is used in simple experiments. The radiant output power and efficiency of the laser are measured, and polarization of the light beam is shown. The "h/e" ratio is available from the threshold of spontaneous emission. The lasing threshold is found using several methods. With a…

  14. Laser cooling of beryllium ions using a frequency-doubled 626 nm diode laser

    NARCIS (Netherlands)

    Cozijn, F.M.J.; Biesheuvel, J.; Flores, A.S.; Ubachs, W.M.G.; Blume, G.; Wicht, A.; Paschke, K.; Erbert, G.; Koelemeij, J.C.J.

    2013-01-01

    We demonstrate laser cooling of trapped beryllium ions at 313 nm using a frequency-doubled extended cavity diode laser operated at 626 nm, obtained by cooling a ridge waveguide diode laser chip to -31°C. Up to 32 mW of narrowband 626 nm laser radiation is obtained. After passage through an optical

  15. Bistable direction switching in an off-axis pumped continuous wave ruby laser

    Science.gov (United States)

    Afzal, R. Sohrab; Lawandy, N. M.

    1988-01-01

    A report is presented of the observation of hysteretic bistable direction switching in a single-mode CW ruby laser system. This effect is only observed when the pump beam which is focused into the ruby rod is misaligned with respect to the rod end faces. At low pump powers, the ruby lases in a mode nearly collinear with the pump axis. At a higher pump power the ruby switches to a mode that is collinear with the rod end faces and preserves the original polarization. The effect is large enough to switch the beam by an angle equal to twice the diffraction angle. The observations show that under steady-state pumping, a CW ruby laser can exhibit bistable operation in its output direction and power. A calculation using the heat equation with two concentric cylinders with one as a heat source (pump laser) and the outer wall of the other held at 77 K, gives an increase in core temperature of about 0.01 K. Therefore, the increase in temperature is not large enough to change the index of refraction to account for such large macroscopic effects.

  16. Generation conditions of CW Diode Laser Sustained Plasma

    Science.gov (United States)

    Nishimoto, Koji; Matsui, Makoto; Ono, Takahiro

    2016-09-01

    Laser sustained plasma was generated using 1 kW class continuous wave diode laser. The laser beam was focused on the seed plasma generated by arc discharge in 1 MPa xenon lamp. The diode laser has advantages of high energy conversion efficiency of 80%, ease of maintenance, compact size and availability of conventional quartz based optics. Therefore, it has a prospect of further development compared with conventional CO2 laser. In this study, variation of the plasma shape caused by laser power is observed and also temperature distribution in the direction of plasma radius is measured by optical emission spectroscopy.

  17. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.

  18. Modular package for cooling a laser diode array

    Science.gov (United States)

    Mundinger, David C.; Benett, William J.; Beach, Raymond J.

    1992-01-01

    A laser diode array is disclosed that includes a plurality of planar packages and active cooling. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar package having the laser diode bar located proximate to one edge. In an array, a number of such thin planar packages are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink that is attached proximate to the laser bar so that it absorbs heat generated by laser operation. To provide the coolant to the microchannels, each thin planar package comprises a thin inlet manifold and a thin outlet manifold connected to an inlet corridor and an outlet corridor. The inlet corridor comprises a hole extending through each of the packages in the array, and the outlet corridor comprises a hole extending through each of the packages in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has application as an optical pump for high power solid state lasers. Further, it can be incorporated in equipment such as communications devices and active sensors, and in military and space applications, and it can be useful in applications having space constraints and energy limitations.

  19. Crossbar memory array of organic bistable rectifying diodes for nonvolatile data storage

    NARCIS (Netherlands)

    Asadi, Kamal; Li, Mengyuan; Stingelin, Natalie; Blom, Paul W. M.; de Leeuw, Dago M.

    2010-01-01

    Cross-talk in memories using resistive switches in a cross-bar geometry can be prevented by integration of a rectifying diode. We present a functional cross bar memory array using a phase separated blend of a ferroelectric and a semiconducting polymer as storage medium. Each intersection acts

  20. Active stabilization of a diode laser injection lock.

    Science.gov (United States)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-06-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  1. Short range laser obstacle detector. [for surface vehicles using laser diode array

    Science.gov (United States)

    Kuriger, W. L. (Inventor)

    1973-01-01

    A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

  2. Micropulse diode laser trabeculoplasty -- 180-degree treatment.

    Science.gov (United States)

    Rantala, Elina; Välimäki, Juha

    2012-08-01

    To evaluate the outcome of 180° micropulse diode laser trabeculoplasty (MDLT) in patients with open-angle glaucoma. A retrospective review of 40 eyes of 29 MDLT-treated patients with a minimum follow-up time of 6 months. Successful outcome was defined as follows: (i) a ≥20% or (ii) a ≥3-mmHg decrease of intraocular pressure (IOP), no further need for laser- or incisional surgery and the number of glaucoma medication was the same or less than preoperative. These definitions will from now on be referred to as definition one and definition two. Life-table analysis showed an overall success rate of 2.5% (1/40) and 7.5% (3/40) (according to definitions one and two, respectively) after up to 19 months of follow-up. The average time for failure was by definition one 2.9 months (standard deviation, SD ± 3.5, range 1-12 months) and by definition two 3.3 months (SD ± 3.9, range 1-16 months). There were no intra- or postoperative complications caused by MDLT. Postoperative inflammatory reaction, cells and flare, was scanty. Our results suggest that 180° MDLT is a safe but ineffective treatment in patients with open-angle glaucoma. © 2010 The Authors. Acta Ophthalmologica © 2010 Acta Ophthalmologica Scandinavica Foundation.

  3. Active stabilization of a diode laser injection lock

    Energy Technology Data Exchange (ETDEWEB)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep [Department of Physics, University of Washington, P.O. Box 351560, Seattle, Washington 98195-1560 (United States)

    2016-06-15

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  4. Effect of different diode laser powers in photodynamic therapy

    CSIR Research Space (South Africa)

    Maduray, K

    2010-09-01

    Full Text Available This preliminary photodynamic therapy study investigated the effect of different diode laser powers (mW) for the activation of two photosensitizers (AlTSPc, aluminum tetrasulfonatedphthalocyanine and ZnTSPc, zinc tetrasulfonatedphthalocyanine...

  5. Unmanned Aerial Vehicle Diode Laser Sensor for Methane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact, lightweight, and low power diode laser sensor will be developed for atmospheric methane detection on small unmanned aerial vehicles (UAVs). The physical...

  6. Active stabilization of a diode laser injection lock

    International Nuclear Information System (INIS)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  7. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  8. Active Stabilization of a Diode Laser Injection Lock

    OpenAIRE

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudde...

  9. Spectral beam combining of diode lasers with high efficiency

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2012-01-01

    Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation.......Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation....

  10. Advances in AlGaInN laser diode technology

    Science.gov (United States)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Bockowski, Mike; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

    2014-03-01

    The latest developments in AlGaInN laser diode technology are reviewed. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of >100mW in the 400-420nm wavelength range that are suitable for telecom applications. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported. High power operation of AlGaInN laser diodes is demonstrated with a single chip, AlGaInN laser diode `mini-array' with a common p-contact configuration at powers up to 2.5W cw at 410nm. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. GaN laser bars of up to 5mm with 20 emitters, mounted in a CS mount package, give optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.

  11. Tradeoff between laser diodes and light-emitting diodes (LEDs) for the common weapon control system

    Science.gov (United States)

    Greenwell, R. A.

    1982-07-01

    The use of laser diodes or light emitting diodes (LEDs) for the ground-launched cruise missile (GLCM) is comparatively evaluated. Source characteristics of interest, including radiated power output, spectral width and peak emission, modulation bandwidth, size coupling efficiency, lifetime, rise time, and price, are presented for noncoherent LED and the coherent laser diode. The advantages and disadvantages of laser diodes and LEDs are briefly discussed, and nuclear explosion effects on these instruments, including catastrophic damage, transient ionization effects, and permanent degradation, are summarized. A link analysis of the cable parameters required for the GLCM fiber optic data link is given, arriving at power levels consistent with a LED-PIN link. Two LEDs which meet these requirements are briefly discussed.

  12. High Power High Efficiency Diode Laser Stack for Processing

    Science.gov (United States)

    Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

    2018-03-01

    High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

  13. Features of laser diodes' radiation in different temperature intervals

    Directory of Open Access Journals (Sweden)

    Vlasova S. V.

    2017-12-01

    Full Text Available In the literature there is practically no information on the change in the characteristics of the emission spectrum of industrial semiconductor laser diodes in a wide range of temperatures, including cryogenic temperatures. Nevertheless, this information is decisive when choosing specific laser diodes for industrial devices. An experimental study of features of the emission spectra of laser semiconductor diodes in the temperature range 50–300 K has been conducted. The material used in the laser diodes' manufacture is a compound based on the solid quaternary AlGaInP solution. The radiation spectrum has been investigated using a monochromator MDR-23 with a CCD detector installed. The study has proved that the temperature of the laser diode operation determines the nature of the radiation spectrum, in particular the predominance of stimulated or induced radiation has taken place, the range of wavelengths of radiation changes as well. It is believed that in the temperature range from 50 to 300 K in the volume of the laser diode material some processes are realized, as a result of which the value of the forbidden band width changes, it decreases by approximately 4.2–4.5 % from the value corresponding to the temperature of 50 K. The calculation of the value of the temperature coefficient of the change in the forbidden band width has shown that in the temperature range from 50 to 300 K the meaning of βvaries in absolute value by 2–3 times. A new experimental method for determining ionization energies of exciton levels has been proposed. It is of practical use for monitoring the electro-physical parameters of semiconductor materials used in the manufacture of industrial semiconductor lasers. The advantage of the proposed method is the ability to obtain qualitative and quantitative information about the exciton spectrum of the laser diode material directly in the region of the p–n-junction where the laser radiation is formed

  14. Disruptive laser diode source for embedded LIDAR sensors

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2017-02-01

    Active imaging based on laser illumination is used in various fields such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified these last years with an emphasis on lidar technology that is probably the key to achieve full automation level. Based on time-of-flight measurements, the profile of objects can be measured together with their location in various conditions, creating a 3D mapping of the environment. To be embedded on a vehicle as advanced driver assistance systems (ADAS), these sensors require compactness, low-cost and reliability, as it is provided by a flash lidar. An attractive candidate, especially with respect to cost reduction, for the laser source integrated in these devices is certainly laser diodes as long as they can provide sufficiently short pulses with a high energy. A recent breakthrough in laser diode and diode driver technology made by Quantel (Les Ulis, France) now allows laser emission higher than 1 mJ with pulses as short as 12 ns in a footprint of 4x5 cm2 (including both the laser diode and driver) and an electrical-to-optical conversion efficiency of the whole laser diode source higher than 25% at this level of energy. The components used for the laser source presented here can all be manufactured at low cost. In particular, instead of having several individual laser diodes positioned side by side, the laser diodes are monolithically integrated on a single semiconductor chip. The chips are then integrated directly on the driver board in a single assembly step. These laser sources emit in the range of 800-1000 nm and their emission is considered to be eye safe when taking into account the high divergence of the output beam and the aperture of possible macro lenses so that they can be used for end consumer applications. Experimental characterization of these state-of-the-art pulsed laser diode sources

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

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2012-01-01

    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...... lasers emerge as the next generation of compact lasers that have the potential of replacing conventional high power laser systems in many existing applications....

  16. Hybrid optoelectronic device with multiple bistable outputs

    Science.gov (United States)

    Costazo-Caso, Pablo A.; Jin, Yiye; Gelh, Michael; Granieri, Sergio; Siahmakoun, Azad

    2011-01-01

    Optoelectronic circuits which exhibit optical and electrical bistability with hysteresis behavior are proposed and experimentally demonstrated. The systems are based on semiconductor optical amplifiers (SOA), bipolar junction transistors (BJT), PIN photodiodes (PD) and laser diodes externally modulated with integrated electro-absorption modulators (LD-EAM). The device operates based on two independent phenomena leading to both electrical bistability and optical bistability. The electrical bistability is due to the series connection of two p-i-n structures (SOA, BJT, PD or LD) in reverse bias. The optical bistability is consequence of the quantum confined Stark effect (QCSE) in the multi-quantum well (MQW) structure in the intrinsic region of the device. This effect produces the optical modulation of the transmitted light through the SOA (or reflected from the PD). Finally, because the optical transmission of the SOA (in reverse bias) and the reflected light from the PD are so small, a LD-EAM modulated by the voltage across these devices are employed to obtain a higher output optical power. Experiments show that the maximum switching frequency is in MHz range and the rise/fall times lower than 1 us. The temporal response is mainly limited by the electrical capacitance of the devices and the parasitic inductances of the connecting wires. The effects of these components can be reduced in current integration technologies.

  17. Wavelength-Agile External-Cavity Diode Laser for DWDM

    Science.gov (United States)

    Pilgrim, Jeffrey S.; Bomse, David S.

    2006-01-01

    A prototype external-cavity diode laser (ECDL) has been developed for communication systems utilizing dense wavelength- division multiplexing (DWDM). This ECDL is an updated version of the ECDL reported in Wavelength-Agile External- Cavity Diode Laser (LEW-17090), NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 14a. To recapitulate: The wavelength-agile ECDL combines the stability of an external-cavity laser with the wavelength agility of a diode laser. Wavelength is modulated by modulating the injection current of the diode-laser gain element. The external cavity is a Littman-Metcalf resonator, in which the zeroth-order output from a diffraction grating is used as the laser output and the first-order-diffracted light is retro-reflected by a cavity feedback mirror, which establishes one end of the resonator. The other end of the resonator is the output surface of a Fabry-Perot resonator that constitutes the diode-laser gain element. Wavelength is selected by choosing the angle of the diffracted return beam, as determined by position of the feedback mirror. The present wavelength-agile ECDL is distinguished by design details that enable coverage of all 60 channels, separated by 100-GHz frequency intervals, that are specified in DWDM standards.

  18. Amplification of an Autodyne Signal in a Bistable Vertical-Cavity Surface-Emitting Laser with the Use of a Vibrational Resonance

    Science.gov (United States)

    Chizhevsky, V. N.

    2018-01-01

    For the first time, it is demonstrated experimentally that a vibrational resonance in a polarization-bistable vertical-cavity surface-emitting laser can be used to increase the laser response in autodyne detection of microvibrations from reflecting surfaces. In this case, more than 25-fold signal amplification is achieved. The influence of the asymmetry of the bistable potential on the microvibration-detection efficiency is studied.

  19. Power blue and green laser diodes and their applications

    Science.gov (United States)

    Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

    2013-03-01

    InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

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

    NARCIS (Netherlands)

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

    2015-01-01

    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

  1. Dichroic mirror for diode pumped YAG:Nd-laser

    DEFF Research Database (Denmark)

    Dinca, Andreea; Skettrup, Torben; Lupei, V.

    1996-01-01

    The paper describes the design and realization of a dichroic mirror for a diode pumped YAG:Nd laser. The mirror is deposed on an optical glass substrate and works in optical contact with the laser crystal. The design was performed by admittance matching of the basic stack with the adjacent media...

  2. Design of a high power laser diode driver

    Science.gov (United States)

    Li, Wen-jiang; Wang, Qian-qian; Liu, Li; Peng, Zhong

    2013-12-01

    Laser diodes are preferred light sources for compact non-scanning imaging laser radar systems due to their small volume and easiness to be integrated. Therefore, lots of present studies focus on research of modulation characteristics of highpower laser diodes. A high-frequency modulated driver for a compact non-scanning imaging laser radar system is described in this paper. It is based on linear constant current theory and can modulate a high power laser diode quasi-continuously. A high-speed operational amplifier is used to drive a power MOSFET, which can take full advantages of the power MOSFET-low driver current and good dynamic characteristics. In addition, an operational amplifier and PI (Proportion-Integration) control are applied in a negative feedback network to improve the current stability further. In order to avoid damaging the laser diode, a slow start circuit and over-current protection circuit have also been designed. The maximum current of the over-current protection circuit can be set according to the requirement. In addition, the power supply can also be switched between CW and QCW operating modes. When the high power semiconductor laser is modulated by large signal, some nonlinear effects will occur such as turn-on delay, relaxation oscillation and modulation chirp. Some theoretical analysis and experimental research on some nonlinear effects have also been done. Experimental results are consistent with theoretical analysis by using this driver for a 1W GaAs quantum well laser.

  3. High average power diode pumped solid state lasers for CALIOPE

    International Nuclear Information System (INIS)

    Comaskey, B.; Halpin, J.; Moran, B.

    1994-07-01

    Diode pumping of solid state media offers the opportunity for very low maintenance, high efficiency, and compact laser systems. For remote sensing, such lasers may be used to pump tunable non-linear sources, or if tunable themselves, act directly or through harmonic crystals as the probe. The needs of long range remote sensing missions require laser performance in the several watts to kilowatts range. At these power performance levels, more advanced thermal management technologies are required for the diode pumps. The solid state laser design must now address a variety of issues arising from the thermal loads, including fracture limits, induced lensing and aberrations, induced birefringence, and laser cavity optical component performance degradation with average power loading. In order to highlight the design trade-offs involved in addressing the above issues, a variety of existing average power laser systems are briefly described. Included are two systems based on Spectra Diode Laboratory's water impingement cooled diode packages: a two times diffraction limited, 200 watt average power, 200 Hz multi-rod laser/amplifier by Fibertek, and TRW's 100 watt, 100 Hz, phase conjugated amplifier. The authors also present two laser systems built at Lawrence Livermore National Laboratory (LLNL) based on their more aggressive diode bar cooling package, which uses microchannel cooler technology capable of 100% duty factor operation. They then present the design of LLNL's first generation OPO pump laser for remote sensing. This system is specified to run at 100 Hz, 20 nsec pulses each with 300 mJ, less than two times diffraction limited, and with a stable single longitudinal mode. The performance of the first testbed version will be presented. The authors conclude with directions their group is pursuing to advance average power lasers. This includes average power electro-optics, low heat load lasing media, and heat capacity lasers

  4. Computer Processing Of Tunable-Diode-Laser Spectra

    Science.gov (United States)

    May, Randy D.

    1991-01-01

    Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

  5. Photoporation and cell transfection using a violet diode laser

    Science.gov (United States)

    Paterson, L.; Agate, B.; Comrie, M.; Ferguson, R.; Lake, T. K.; Morris, J. E.; Carruthers, A. E.; Brown, C. T. A.; Sibbett, W.; Bryant, P. E.; Gunn-Moore, F.; Riches, A. C.; Dholakia, Kishan

    2005-01-01

    The introduction and subsequent expression of foreign DNA inside living mammalian cells (transfection) is achieved by photoporation with a violet diode laser. We direct a compact 405 nm laser diode source into an inverted optical microscope configuration and expose cells to 0.3 mW for 40 ms. The localized optical power density of ~1200 MW/m2 is six orders of magnitude lower than that used in femtosecond photoporation (~104 TW/m2). The beam perforates the cell plasma membrane to allow uptake of plasmid DNA containing an antibiotic resistant gene as well as the green fluorescent protein (GFP) gene. Successfully transfected cells then expand into clonal groups which are used to create stable cell lines. The use of the violet diode laser offers a new and simple poration technique compatible with standard microscopes and is the simplest method of laser-assisted cell poration reported to date.

  6. Doping Optimization for High Efficiency in Semiconductor Diode Lasers and Amplifiers

    Science.gov (United States)

    2016-03-01

    JOURNAL OF QUANTUM ELECTRONICS, VOL. , NO. , 1 Doping Optimization for High Efficiency in Semiconductor Diode Lasers and Amplifiers Dominic F...Siriani, Member, IEEE Abstract—A generalized theoretical formalism is derived that optimizes the doping profile of semiconductor diode lasers and amplifiers...Diode lasers, semiconductor lasers, semiconduc- tor optical amplifiers. I. INTRODUCTION ELECTRICALLY injected diode lasers have been demon-strated in many

  7. An auto-locked diode laser system for precision metrology

    Science.gov (United States)

    Beica, H. C.; Carew, A.; Vorozcovs, A.; Dowling, P.; Pouliot, A.; Barron, B.; Kumarakrishnan, A.

    2017-05-01

    We present a unique external cavity diode laser system that can be auto-locked with reference to atomic and molecular spectra. The vacuum-sealed laser head design uses an interchangeable base-plate comprised of a laser diode and optical elements that can be selected for desired wavelength ranges. The feedback light to the laser diode is provided by a narrow-band interference filter, which can be tuned from outside the laser cavity to fineadjust the output wavelength in vacuum. To stabilize the laser frequency, the digital laser controller relies either on a pattern-matching algorithm stored in memory, or on first or third derivative feedback. We have used the laser systems to perform spectroscopic studies in rubidium at 780 nm, and in iodine at 633 nm. The linewidth of the 780-nm laser system was measured to be ˜500 kHz, and we present Allan deviation measurements of the beat note and the lock stability. Furthermore, we show that the laser system can be the basis for a new class of lidar transmitters in which a temperature-stabilized fiber-Bragg grating is used to generate frequency references for on-line points of the transmitter. We show that the fiber-Bragg grating spectra can be calibrated with reference to atomic transitions.

  8. Violet Laser Diode Enables Lighting Communication.

    Science.gov (United States)

    Chi, Yu-Chieh; Huang, Yu-Fang; Wu, Tsai-Chen; Tsai, Cheng-Ting; Chen, Li-Yin; Kuo, Hao-Chung; Lin, Gong-Ru

    2017-09-05

    Violet laser diode (VLD) based white-light source with high color rendering index (CRI) for lighting communication is implemented by covering with Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) or Lu 3 Al 5 O 12 :Ce 3+ /CaAlSiN 3 :Eu 2+ (LuAG:Ce/CASN:Eu) phosphorous diffuser plates. After passing the beam of VLD biased at 70 mA (~2I th ) through the YAG:Ce phosphorous diffuser, a daylight with a correlated color temperature (CCT) of 5068 K and a CRI of 65 is acquired to provide a forward error correction (FEC) certified data rate of 4.4 Gbit/s. By using the VLD biased at 122 mA (~3.5I th ) to excite the LuAG:Ce/CASN:Eu phosphorous diffuser with 0.85-mm thickness, a warm white-light source with a CCT of 2700 K and a CRI of 87.9 is obtained at a cost of decreasing transmission capacity to 2.4 Gbit/s. Thinning the phosphor thickness to 0.75 mm effectively reduces the required bias current by 32 mA to achieve the same CCT for the delivered white light, which offers an enlarged CRI of 89.1 and an increased data rate of 4.4 Gbit/s. Further enlarging the bias current to 105 mA remains the white-light transmission capacity at 4.4 Gbit/s but reveals an increased CCT of 3023 K and an upgraded CRI of 91.5.

  9. Inferior turbinate reduction: Diode laser or conventional partial turbinectomy?

    Science.gov (United States)

    Doreyawar, Venkatesh; Gadag, Raveendra P; Manjunath, Dandi Narasaiah; Javali, Shivalingappa B; Maradi, Nagaraj; Shetty, Deekshit

    2018-01-01

    Hypertrophy of the inferior nasal turbinate is one of the most common causes of nasal obstruction. The diode laser has proven to be as effective as other lasers for this indication. Our objective was to study various outcomes associated with the use of the diode laser, such as improvements in nasal obstruction and postoperative pain, reduction in intraoperative bleeding, and rapidity of healing. A nonrandomized, controlled trial was conducted in which outcomes were compared between diode laser turbinate reduction (LTR) and conventional partial inferior turbinectomy (PIT) in 60 patients, 30 who underwent LTR and 30 who underwent PIT. The improvement in nasal obstruction was measured postoperatively up to 6 months. Intraoperative bleeding was measured and postoperative pain scores were assessed each day up to the fifth postoperative day. Rapidity of healing was evaluated until 6 months postoperatively. Subjective relief of nasal obstruction occurred in 90.8% of the LTR group and 65% of the PIT group at 6 months (p diode laser were better and diode LTR caused less morbidity compared with the conventional technique.

  10. Determination of QW laser diode degradation based on the emission spectrum

    Directory of Open Access Journals (Sweden)

    Bliznyuk Vladimir

    2017-01-01

    Full Text Available The possibility of laser diodes degradation control by monitoring of their spectrum is shown. For red and infra-red laser diodes, the time dependence of the radiation spectrum width was obtained.

  11. Portable Diode Laser Diagnostic System for Collaborative Research on Air-Breathing Combustion

    National Research Council Canada - National Science Library

    Hanson, Ronald

    2003-01-01

    This equipment grant focused on four areas: (1) portable diode laser sensors with new fiber-coupled diode lasers and the support equipment to provide higher power with extended wavelength tuning range and speed; (2...

  12. Future Solid State Lighting using LEDs and Diode Lasers

    DEFF Research Database (Denmark)

    Petersen, Paul Michael

    2014-01-01

    significant savings. Solid state lighting (SSL) based on LEDs is today the most efficient light source for generation of high quality white light. Diode lasers, however, have the potential of being more efficient than LEDs for the generation of white light. A major advantage using diode lasers for solid state......Lighting accounts for 20% of all electrical energy usage. Household lighting and commercial lighting such as public and street lighting are responsible for significant greenhouse gas emissions. Therefore, currently many research initiatives focus on the development of new light sources which shows...... lighting is that the high efficiency can be obtained at high light lumen levels in a single element emitter and thus less light sources are required to achieve a desired light level. Furthermore, the high directionality of the generated light from laser diodes increases the energy savings in many...

  13. Microchannel heatsinks for high-average-power laser diode arrays

    Science.gov (United States)

    Benett, William J.; Freitas, Barry L.; Beach, Raymond J.; Ciarlo, Dino R.; Sperry, Verry; Comaskey, Brian J.; Emanuel, Mark A.; Solarz, Richard W.; Mundinger, David C.

    1992-06-01

    Detailed performance results and fabrication techniques for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or even CW operation of fully filled laser diode arrays is enabled at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using a photolithographic pattern definition procedure followed by anisotropic chemical etching. A modular rack-and-stack architecture is adopted for the heatsink design allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel cooled heatsinks is ideally suited to pump array requirements for high average power crystalline lasers because of the stringent temperature demands that result from coupling the diode light to several nanometers wide absorption features characteristic of lasing ions in crystals.

  14. High brightness laser source based on polarization coupling of two diode lasers with asymmetric feedback

    DEFF Research Database (Denmark)

    Thestrup, B.; Chi, M.; Sass, B.

    2003-01-01

    200 mum broad area laser diode applied with a specially designed feedback circuit. When operating at two times threshold, 50% of the freely running system output power is obtained in a single beam with an M-2 beam quality factor of 1.6+/-0.1, whereas the M-2 values of the two freely running diode......In this letter, we show that polarization coupling and asymmetric diode-laser feedback can be used to combine two diode-laser beams with low spatial coherence into a single beam with high spatial coherence. The coupled laser source is based on two similar laser systems each consisting of a 1 mumx...... lasers are 29+/-1 and 34+/-1, respectively. (C) 2003 American Institute of Physics....

  15. Comparative hazard evaluation of near-infrared diode lasers.

    Science.gov (United States)

    Marshall, W J

    1994-05-01

    Hazard evaluation methods from various laser protection standards differ when applied to extended-source, near-infrared lasers. By way of example, various hazard analyses are applied to laser training systems, which incorporate diode lasers, specifically those that assist in training military or law enforcement personnel in the proper use of weapons by simulating actual firing by the substitution of a beam of near-infrared energy for bullets. A correct hazard evaluation of these lasers is necessary since simulators are designed to be directed toward personnel during normal use. The differences among laser standards are most apparent when determining the hazard class of a laser. Hazard classification is based on a comparison of the potential exposures with the maximum permissible exposures in the 1986 and 1993 versions of the American National Standard for the Safe Use of Lasers, Z136.1, and the accessible emission limits of the federal laser product performance standard. Necessary safety design features of a particular system depend on the hazard class. The ANSI Z136.1-1993 standard provides a simpler and more accurate hazard assessment of low-power, near-infrared, diode laser systems than the 1986 ANSI standard. Although a specific system is evaluated, the techniques described can be readily applied to other near-infrared lasers or laser training systems.

  16. Diode laser vaporisation of the prostate vs. diode laser under cold irrigation: A randomised control trial.

    Science.gov (United States)

    Pillai, Ravisankar G; Al Naieb, Ziad; Angamuthu, Stephen; Mundackal, Tintu

    2014-12-01

    To compare the perioperative morbidity and early follow-up after diode laser vaporisation of the prostate (LVP) and its modification, diode laser under cold irrigation (LUCI) in patients with symptomatic benign prostatic hyperplasia, as the main disadvantages of LVP are the postoperative pain, dysuria and storage urinary symptoms. This was a single-centre prospective randomised control trial in which 100 patients were randomised to receive LVP (50) or LUCI (50) from June 2011 until July 2012. LUCI is similar to LVP except that it is done under normal irrigation with saline at 4 °C instead of saline at room temperature. The primary outcome measures were the International Prostate Symptom Score (IPSS), IPSS-Dysuria, a pain scale (PS), maximum flow rate (Q max), a quality-of-life (QoL) score and the postvoid residual urine volume (PVR) after 1 month, then the IPSS, Q max, QoL, and PVR at 3 and 12 months. Secondary outcomes included intraoperative surgical variables, e.g., the decline in core temperature, bleeding, peri- and postoperative morbidity. The baseline characteristics of both groups were similar. For the primary outcome measures, there was a statistically significant difference between the groups in all variables except Q max after 1 month, in favour of LUCI. The mean (SD) IPSS at 1 month in the LVP group was 8.97 (1.68), statistically significantly different from that after LUCI, of 6.89 (1.5) (P  0.05). LUCI is a good modification for reducing the pain, dysuria and storage symptoms associated with LVP. The procedure appears to be safe, with no significant decrease in core temperature in either group.

  17. Mathematical modeling of a passively Q-switched diode laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2009-11-01

    A mathematical model describing the dynamic emission of the intracavity frequency doubling (IFD) of a gain-switched InGaAs/GaAs/KTP and a gain-switched mode-locked two-sections tapered ridge-waveguide InGaAs/GaAs diode laser has been presented. The IFD of a gain-switched and a gain-switched mode-locked two-sections diode laser is modeled where one section is electrically pumped to proved gain while the second section is unpumped (reverse biased) to provide a saturable absorber. (author)

  18. Electrooptic modulation methods for high sensitivity tunable diode laser spectroscopy

    Science.gov (United States)

    Glenar, David A.; Jennings, Donald E.; Nadler, Shacher

    1990-01-01

    A CdTe phase modulator and low power RF sources have been used with Pb-salt tunable diode lasers operating near 8 microns to generate optical sidebands for high sensitivity absorption spectroscopy. Sweep averaged, first-derivative sample spectra of CH4 were acquired by wideband phase sensitive detection of the electrooptically (EO) generated carrier-sideband beat signal. EO generated beat signals were also used to frequency lock the TDL to spectral lines. This eliminates low frequency diode jitter, and avoids the excess laser linewidth broadening that accompanies TDL current modulation frequency locking methods.

  19. Gummy Smile Correction with Diode Laser: Two Case Reports.

    Science.gov (United States)

    Narayanan, Mahesh; Laju, S; Erali, Susil M; Erali, Sunil M; Fathima, Al Zainab; Gopinath, P V

    2015-01-01

    Beautification of smiles is becoming an everyday requirement in dental practice. Apart from teeth, gingiva also plays an important role in smile esthetics. Excessive visualization of gingiva is a common complaint among patients seeking esthetic treatment. A wide variety of procedures are available for correction of excessive gum display based on the cause of the condition. Soft tissue diode laser contouring of gingiva is a common procedure that can be undertaken in a routine dental setting with excellent patient satisfaction and minimal post-operative sequale. Two cases of esthetic crown lengthening with diode laser 810 nm are presented here.

  20. Characteristic of laser diode beam propagation through a collimating lens.

    Science.gov (United States)

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

    A mathematical model of a laser diode beam propagating through a collimating lens is presented. Wave propagation beyond the paraxial approximation is studied. The phase delay of the laser diode wave in passing through the lens is analyzed in detail. The propagation optical field after the lens is obtained from the diffraction integral by the stationary phase method. The model is employed to predict the light intensity at various beam cross sections, and the computed intensity distributions are in a good agreement with the corresponding measurements.

  1. Frequency-doubled diode laser for direct pumping of Ti:sapphire lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika

    2012-01-01

    A single-pass frequency doubled high-power tapered diode laser emitting nearly 1.3 W of green light suitable for direct pumping of Ti:sapphire lasers generating ultrashort pulses is demonstrated. The pump efficiencies reached 75 % of the values achieved with a commercial solid-state pump laser....... However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20...... fs are measured. These results open the opportunity of establishing diode laser pumped Ti:sapphire lasers for e.g. biophotonic applications like retinal optical coherence tomography or pumping of photonic crystal fibers for CARS microscopy....

  2. Blue laser diode (LD) and light emitting diode (LED) applications

    International Nuclear Information System (INIS)

    Bergh, Arpad A.

    2004-01-01

    The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography. As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc. Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity. Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Low-cost photoacoustic imaging systems based on laser diode and light-emitting diode excitation

    Directory of Open Access Journals (Sweden)

    Qingkai Yao

    2017-07-01

    Full Text Available Photoacoustic imaging, an emerging biomedical imaging modality, holds great promise for preclinical and clinical researches. It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission. In order to generate photoacoustic signal efficiently, bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization. As an alternative, the miniaturized semiconductor laser system has the advantages of being inexpensive, compact, and robust, which makes a significant effect on production-forming design. It is also desirable to obtain a wavelength in a wide range from visible to near-infrared spectrum for multispectral applications. Focussing on practical aspect, this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.

  4. Development of diode-pumped medical solid-state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk

    2000-09-01

    Two thirds of human body consists of water and the absorption of laser by water is an important factor in medical laser treatment. Er medical lasers have been used in the dermatology, ophthalmology and dental treatments due to its highest absorption by water. However, 2.9 um Er laser can not be transmitted through an optical fiber. On the other hand, Tm laser can be transmitted through an fiber and also has very high absorption by water. Therefore, Tm lasers are used in ophthalmology and heart treatment wherein the fiber delivery is very important for the treatment. Until now, mainly lamp-pumped solid-state lasers have been used in medical treatments, but the lamp-pumped solid-state lasers are being replaced with the diode-pumped solid-state lasers because the diode-pumped solid-state lasers are more compact and much easier to maintain. Following this trend, end-pumped Er and side-pumped Tm lasers have been developed and the output power of 1 W was obtained for Er and Tm respectively.

  5. Development of diode-pumped medical solid-state lasers

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Min Suk

    2000-09-01

    Two thirds of human body consists of water and the absorption of laser by water is an important factor in medical laser treatment. Er medical lasers have been used in the dermatology, ophthalmology and dental treatments due to its highest absorption by water. However, 2.9 um Er laser can not be transmitted through an optical fiber. On the other hand, Tm laser can be transmitted through an fiber and also has very high absorption by water. Therefore, Tm lasers are used in ophthalmology and heart treatment wherein the fiber delivery is very important for the treatment. Until now, mainly lamp-pumped solid-state lasers have been used in medical treatments, but the lamp-pumped solid-state lasers are being replaced with the diode-pumped solid-state lasers because the diode-pumped solid-state lasers are more compact and much easier to maintain. Following this trend, end-pumped Er and side-pumped Tm lasers have been developed and the output power of 1 W was obtained for Er and Tm respectively

  6. Diode laser-based detection in liquid chromatography and capillary electrophoresis.

    NARCIS (Netherlands)

    Mank, A.J.G.; Lingeman, H.; Gooijer, C.

    1996-01-01

    Detection techniques involving diode lasers are increasingly of interest in separation science, Diode lasers are small and inexpensive and have a very stable output. However, diode lasers emitting at wavelengths shorter than 635 nm are not commercially available. This seriously limits the

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  8. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    Science.gov (United States)

    Mach, J. J.; Varghese, P. L.; Jagodzinski, J. J.

    1999-01-01

    The ability of solid-state lasers to be tuned in operating frequency at MHz rates by input current modulation, while maintaining a relatively narrow line-width, has made them useful for spectroscopic measurements. Their other advantages include low cost, reliability, durability, compact size, and modest power requirements, making them a good choice for a laser source in micro-gravity experiments in drop-towers and in flight. For their size, they are also very bright. In a filtered Rayleigh scattering (FRS) experiment, a diode laser can be used to scan across an atomic or molecular absorption line, generating large changes in transmission at the resonances for very small changes in frequency. The hyperfine structure components of atomic lines of alkali metal vapors are closely spaced and very strong, which makes such atomic filters excellent candidates for sensitive Doppler shift detection and therefore for high-resolution velocimetry. In the work we describe here we use a Rubidium vapor filter, and work with the strong D(sub 2) transitions at 780 nm that are conveniently accessed by near infrared diode lasers. The low power output of infrared laser diodes is their primary drawback relative to other laser systems commonly used for velocimetry. However, the capability to modulate the laser frequency rapidly and continuously helps mitigate this. Using modulation spectroscopy and a heterodyne detection scheme with a lock-in amplifier, one can extract sub-microvolt signals occurring at a specific frequency from a background that is orders of magnitude stronger. The diode laser modulation is simply achieved by adding a small current modulation to the laser bias current. It may also be swept repetitively in wavelength using an additional lower frequency current ramp.

  9. Kerr-lens mode-locked Ti:Sapphire laser pumped by a single laser diode

    Science.gov (United States)

    Kopylov, D. A.; Esaulkov, M. N.; Kuritsyn, I. I.; Mavritskiy, A. O.; Perminov, B. E.; Konyashchenko, A. V.; Murzina, T. V.; Maydykovskiy, A. I.

    2018-04-01

    The performance of a Ti:sapphire laser pumped by a single 461 nm laser diode is presented for both the continuous-wave and the mode-locked regimes of operation. We introduce a simple astigmatism correction scheme for the laser diode beam consisting of two cylindrical lenses affecting the pump beam along the fast axis of the laser diode, which provides the mode-matching between the nearly square-shaped pump beam and the cavity mode. The resulting efficiency of the suggested Ti:Sapphire oscillator pumped by such a laser diode is analyzed for the Ti:sapphire crystals of 3 mm, 5 mm and 10 mm in length. We demonstrate that such a system provides the generation of ultrashort pulses up to 15 fs in duration with the repetition rate of 87 MHz, the average power being 170 mW.

  10. Method and system for homogenizing diode laser pump arrays

    Science.gov (United States)

    Bayramian, Andy J

    2013-10-01

    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  11. Dual-Wavelength Internal-Optically-Pumped Semiconductor Laser Diodes

    Science.gov (United States)

    Green, Benjamin

    Dual-wavelength laser sources have various existing and potential applications in wavelength division multiplexing, differential techniques in spectroscopy for chemical sensing, multiple-wavelength interferometry, terahertz-wave generation, microelectromechanical systems, and microfluidic lab-on-chip systems. In the drive for ever smaller and increasingly mobile electronic devices, dual-wavelength coherent light output from a single semiconductor laser diode would enable further advances and deployment of these technologies. The output of conventional laser diodes is however limited to a single wavelength band with a few subsequent lasing modes depending on the device design. This thesis investigates a novel semiconductor laser device design with a single cavity waveguide capable of dual-wavelength laser output with large spectral separation. The novel dual-wavelength semiconductor laser diode uses two shorter- and longer-wavelength active regions that have separate electron and hole quasi-Fermi energy levels and carrier distributions. The shorter-wavelength active region is based on electrical injection as in conventional laser diodes, and the longer-wavelength active region is then pumped optically by the internal optical field of the shorter-wavelength laser mode, resulting in stable dual-wavelength laser emission at two different wavelengths quite far apart. Different designs of the device are studied using a theoretical model developed in this work to describe the internal optical pumping scheme. The carrier transport and separation of the quasi-Fermi distributions are then modeled using a software package that solves Poisson's equation and the continuity equations to simulate semiconductor devices. Three different designs are grown using molecular beam epitaxy, and broad-area-contact laser diodes are processed using conventional methods. The modeling and experimental results of the first generation design indicate that the optical confinement factor of the

  12. Diode-pumped fiber lasers: a new clinical tool?

    Science.gov (United States)

    Jackson, Stuart D; Lauto, Antonio

    2002-01-01

    Diode-pumped fiber lasers are a compact and an efficient source of high power laser radiation. These laser systems have found wide recognition in the area of lasers as a result of these very practical characteristics and are now becoming important tools for a large number of applications. In this review, we outline the basic physics of fiber lasers and illustrate how a number of clinical procedures would benefit from their employment. The pump mechanisms, the relevant pump and laser transitions between the energy levels, and the main properties of the output from fiber lasers will be briefly reviewed. The main types of high power fiber lasers that have been demonstrated will be examined along with some recent medical applications that have used these lasers. We will also provide a general review of some important medical specialties, highlighting why these fields would gain from the introduction of the fiber laser. It is established that while the fiber laser is still a new form of laser device and hence not commercially available in a wide sense, a number of important medical procedures will benefit from its general introduction into medicine. With the number of medical and surgical applications requiring high power laser radiation steadily increasing, the demand for more efficient and compact laser systems providing this capacity will grow commensurately. The high power fiber laser is one system that looks like a promising modality to meet this need. Copyright 2002 Wiley-Liss, Inc.

  13. Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms.

    Science.gov (United States)

    Hosoya, Toshiyuki; Miranda, Martin; Inoue, Ryotaro; Kozuma, Mikio

    2015-07-01

    We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources for laser cooling experiments including transportable optical lattice clocks.

  14. Management of gingival hyperpigmentation by semiconductor diode laser

    Directory of Open Access Journals (Sweden)

    Geeti Gupta

    2011-01-01

    Full Text Available Gingival hyperpigmentation is caused by excessive deposition of melanin in the basal and suprabasal cell layers of the epithelium. Although melanin pigmentation of the gingiva is completely benign, cosmetic concerns are common, particularly in patients having a very high smile line (gummy smile. Various depigmentation techniques have been employed, such as scalpel surgery, gingivectomy, gingivectomy with free gingival autografting, cryosurgery, electrosurgery, chemical agents such as 90% phenol and 95% alcohol, abrasion with diamond burs, Nd:YAG laser, semiconductor diode laser, and CO 2 laser. The present case report describes simple and effective depigmentation technique using semiconductor diode laser surgery - for gingival depigmentation, which have produced good results with patient satisfaction.

  15. Advancements of ultra-high peak power laser diode arrays

    Science.gov (United States)

    Crawford, D.; Thiagarajan, P.; Goings, J.; Caliva, B.; Smith, S.; Walker, R.

    2018-02-01

    Enhancements of laser diode epitaxy in conjunction with process and packaging improvements have led to the availability of 1cm bars capable of over 500W peak power at near-infrared wavelengths (770nm to 1100nm). Advances in cooler design allow for multi-bar stacks with bar-to-bar pitches as low as 350μm and a scalable package architecture enabled a single diode assembly with total peak powers of over 1MegaWatt of peak power. With the addition of micro-optics, overall array brightness greater than 10kW/cm2 was achieved. Performance metrics of barbased diode lasers specifically engineered for high peak power and high brightness at wavelengths and pulse conditions commonly used to pump a variety of fiber and solid-state materials are presented.

  16. Modeling of diode pumped metastable rare gas lasers.

    Science.gov (United States)

    Yang, Zining; Yu, Guangqi; Wang, Hongyan; Lu, Qisheng; Xu, Xiaojun

    2015-06-01

    As a new kind of optically pumped gaseous lasers, diode pumped metastable rare gas lasers (OPRGLs) show potential in high power operation. In this paper, a multi-level rate equation based model of OPRGL is established. A qualitative agreement between simulation and Rawlins et al.'s experimental result shows the validity of the model. The key parameters' influences and energy distribution characteristics are theoretically studied, which is useful for the optimized design of high efficient OPRGLs.

  17. Diode lasers: A magical wand to an orthodontic practice

    Directory of Open Access Journals (Sweden)

    Vipul Kumar Srivastava

    2014-01-01

    Full Text Available LASER (Light Amplification by Stimulated Emission of Radiation is a powerful source of light, which has innumerable applications in all the fields of science including medicine and dentistry. It is one such technology that has become a desirable and an inseparable alternative to many traditional surgical procedures being held in the field of dentistry, and orthodontics is no exception. The current article describes the uses of a diode laser as an indispensable tool in an orthodontic office.

  18. Chirp of monolithic colliding pulse mode-locked diode lasers

    DEFF Research Database (Denmark)

    Hofmann, M.; Bischoff, S.; Franck, Thorkild

    1997-01-01

    Spectrally resolved streak camera measurements of picosecond pulses emitted by hybridly colliding pulse mode-locked (CPM) laser diodes are presented in this letter. Depending on the modulation frequency both blue-chirped (upchirped) and red-chirped (downchirped) pulses can be observed. The two...... different regimes and the transition between them are characterized experimentally and the behavior is explained on the basis of our model for the CPM laser dynamics. (C) 1997 American Institute of Physics....

  19. Innovative Facet Passivation for High-Brightness Laser Diodes

    Science.gov (United States)

    2016-02-05

    formation process (cleaving) or from contamination from the ambient . (a) Papers published in peer-reviewed journals (N/A for none) Enter List of...funded by a DoD funded Center of Excellence grant for Education , Research and Engineering: The number of undergraduates funded by your agreement who...contamination from the ambient . 15. S U B J E C T T E R M S High-power laser diodes, catastrophic optical damage, high energy lasers 16. SECURITY

  20. Comparing the 810nm Diode Laser with Conventional Surgery in ...

    African Journals Online (AJOL)

    Aim: To compare the use of the 810nm diode laser with conventional surgery in the management of soft tissue mucogingival problems associated with orthodontic treatment. Methods: Orthodontic patients requiring different soft tissue surgical procedures were randomly assigned to receive conventional surgery or soft tissue ...

  1. Multiple diode laser polygon raster output scanner design

    Science.gov (United States)

    Dunn, Susan E.; Ossman, Kenneth R.

    1997-07-01

    The usual xerographic polygon raster output scanner (ROS) design is a set of compromises among speed, image quality, reliability and cost. The design solution presented here pushes the ROS print speed and quality boundaries well beyond the desktop printer while keeping cost low. A dual diode laser source is used to simultaneously write two high resolution, high contrast scan lines that are offset in the cross-scan plane in an underfilled polygon embodiment. The benefits of a dual diode laser design are the high print rate with a low motor polygon assembly (MPA) speed; each beam power is half of that required of a single source; and the electronic data transfer rates are reduced by a factor of two. As the number of sources increases clearly so do these benefits. Reliable and cost effective MPA speeds are limited to less than 30,000 rpm. Multiple diode laser sources impose additional design constraints over single laser sources. The demanding image quality specifications of single laser ROS designs such as spot size and shape, wobble, bow and scan linearity must be achieved while managing new, multiple laser characteristics such as line separation and differential bow. Appropriate compromises of individual image quality parameters must always be made in order to achieve a system design that meets all of the image quality specifications over a reasonable depth of focus.

  2. Endoscopic diode laser therapy for chronic radiation proctitis.

    Science.gov (United States)

    Polese, Lino; Marini, Lucia; Rizzato, Roberto; Picardi, Edgardo; Merigliano, Stefano

    2018-01-01

    The purpose of this study is to determine the effectiveness of endoscopic diode laser therapy in patients presenting rectal bleeding due to chronic radiation proctitis (CRP). A retrospective analysis of CRP patients who underwent diode laser therapy in a single institution between 2010 and 2016 was carried out. The patients were treated by non-contact fibers without sedation in an outpatient setting. Fourteen patients (median age 77, range 73-87 years) diagnosed with CRP who had undergone high-dose radiotherapy for prostatic cancer and who presented with rectal bleeding were included. Six required blood transfusions. Antiplatelet (three patients) and anticoagulant (two patients) therapy was not suspended during the treatments. The patients underwent a median of two sessions; overall, a mean of 1684 J of laser energy per session was used. Bleeding was resolved in 10/14 (71%) patients, and other two patients showed improvement (93%). Only one patient, who did not complete the treatment, required blood transfusions after laser therapy; no complications were noted during or after the procedures. Study findings demonstrated that endoscopic non-contact diode laser treatment is safe and effective in CRP patients, even in those receiving antiplatelet and/or anticoagulant therapy.

  3. Diode laser MIR-DFG spectrometer for trace gas detection

    Science.gov (United States)

    Willer, Ulrike; Blanke, Torsten; Schade, Wolfgang

    1996-10-01

    Two cw-single mode diode-lasers with powers of 30 and 50 mW at the center wavelengths 682 and 791 nm are applied as signal and pump sources for difference frequency generation (DFG) in an AgGaS2 crystal with a length of 30 mm. For 90 degree type I phase matching tunable mid-infrared laser radiation is obtained in the spectral range between 4.9 and 5.1 micrometers , while the DFG-output power is 0.2 (mu) W. The performance of this diode-laser MIR-DFG spectrometer is shown as the absorption of CO for the P(28) rotational line around 2023 cm-1 is probed in a cell and on-line in the exhaust of an engine.

  4. Dye-enhanced diode laser photocoagulation of choroidal neovascularizations

    Science.gov (United States)

    Klingbeil, Ulrich; Puliafito, Carmen A.; McCarthy, Dan; Reichel, Elias; Olk, Joseph; Lesiecki, Michael L.

    1994-06-01

    Dye-enhanced diode laser photocoagulation, using the dye indocyanine green (ICG), has shown some potential in the treatment of choroidal neovascularizations (CNV). A diode laser system was developed and optimized to emit at the absorption maximum of ICG. In a clinical study at two retinal centers, more than 70 patients, the majority of which had age-related macular degeneration, were treated. Eighteen cases with ill-defined subfoveal CNV were followed an average of 11 months after laser treatment. The results show success in resolving the CNV with an average long-term preservation of visual function equal to or superior to data provided by the Macular Photocoagulation Study for confluent burns of low intensity applied to the CNV. Details of the technique and discussion of the controversies inherent in such a treatment strategy will be presented.

  5. Optical vortex generation from a diode-pumped alexandrite laser

    Science.gov (United States)

    Thomas, G. M.; Minassian, A.; Damzen, M. J.

    2018-04-01

    We present the demonstration of an optical vortex mode directly generated from a diode-pumped alexandrite slab laser, operating in the bounce geometry. This is the first demonstration of an optical vortex mode generated from an alexandrite laser or from any other vibronic laser. An output power of 2 W for a vortex mode with a ‘topological charge’ of 1 was achieved and the laser was made to oscillate with both left- and right-handed vorticity. The laser operated at two distinct wavelengths simultaneously, 755 and 759 nm, due to birefringent filtering in the alexandrite gain medium. The result offers the prospect of broadly wavelength tunable vortex generation directly from a laser.

  6. A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery.

    Science.gov (United States)

    Natekar, Madhukar; Raghuveer, Hosahallli-Puttaiah; Rayapati, Dilip-Kumar; Shobha, Eshwara-Singh; Prashanth, Nagesh-Tavane; Rangan, Vinod; Panicker, Archana G

    2017-06-01

    The comparatively evaluate the three surgical treatment modalities namely cryosurgery, diode and CO2 laser surgery in terms of healing outcomes on the day of surgery, first and second week post operatively and recurrence at the end of 18 months was assessed. Thirty selected patients were divided randomly into three groups. Each group comprising of ten patients were subjected to one of the three modalities of treatment namely cryosurgery, diode laser or CO2 laser surgery for ablation of OL. Obtained data was analyzed using mainly using Chi-square and Anova tests. Study showed statistical significant differences (p > 0.05) for evaluation parameters like pain, edema and scar. The parameters like infection, recurrence, bleeding showed no statistical significance. Pain was significantly higher in CO2 laser surgery group as compared with diode laser group. There was no recurrence observed at the end of the 6 months follow up period in all the three study groups. Observations from the study highlights that all three surgical modalities used in this study were effective for treatment of OL, and the overall summation of the results of the study showed that laser therapy (CO2 and Diode) seems to offer better clinically significant results than cryotherapy. Key words: Oral premalignant lesion, leukoplakia, cryosurgery, CO2 laser surgery, diode laser surgery.

  7. Spectral narrowing of a 980 nm tapered diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Lucas Leclin, Gaëlle

    2011-01-01

    in wavelength specific applications and hence, it is vital to stabilize the emission spectrum of these devices. In our experiment, we describe the wavelength narrowing of a 12 element 980 nm tapered diode laser bar using a simple Littman configuration. The tapered laser bar which suffered from a big smile has...... been "smile corrected" using individual phase masks for each emitter. The external cavity consists of the laser bar, both fast and slow axis micro collimators, smile correcting phase mask, 6.5x beam expanding lens combination, a 1200 lines/mm reflecting grating with 85% efficiency in the first order...

  8. Resection of the Tooth Apex with Diode Laser

    Directory of Open Access Journals (Sweden)

    Uzunov Tz.

    2014-06-01

    Full Text Available An “in vitro” experimental study has been carried out on 70 extracted teeth. A laser resection of the root apex has been carried out with diode laser beam with a wavelength of - 810 ± 10 nm. Sequentially a radiation with increasing power has been applied, as follows: 1,3 W, 2W, 3W, 4W, 5W, 6W, 7W, in electro surgery mode. Successful resection of the tooth apex has been performed at: 3W; 4W; 5W; 6W and 7W power. It was established that when laser resected the tooth apex carbonizes.

  9. Frequency-comb-referenced tunable diode laser spectroscopy and laser stabilization applied to laser cooling.

    Science.gov (United States)

    Fordell, Thomas; Wallin, Anders E; Lindvall, Thomas; Vainio, Markku; Merimaa, Mikko

    2014-11-01

    Laser cooling of trapped atoms and ions in optical clocks demands stable light sources with precisely known absolute frequencies. Since a frequency comb is a vital part of any optical clock, the comb lines can be used for stabilizing tunable, user-friendly diode lasers. Here, a light source for laser cooling of trapped strontium ions is described. The megahertz-level stability and absolute frequency required are realized by stabilizing a distributed-feedback semiconductor laser to a frequency comb. Simple electronics is used to lock and scan the laser across the comb lines, and comb mode number ambiguities are resolved by using a separate, saturated absorption cell that exhibits easily distinguishable hyperfine absorption lines with known frequencies. Due to the simplicity, speed, and wide tuning range it offers, the employed technique could find wider use in precision spectroscopy.

  10. Laser-diode-pumped mirror-free Er sup 3+ -doped fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y.; Suzuki, K.; Nakazawa, M. (Optical Communication Laboratory, NTT Transmission Systems Laboratories, Tokai, Ibaraki-ken 319-11, Japan (JP))

    1989-09-15

    We have demonstrated 1.47-{mu}m laser-diode-pumped Er{sup 3+}-doped fiber laser operation at 1.552 {mu}m, in which a cleaved fiber facet with 4% reflectivity is used as the output mirror. The pump source is a 1.47-{mu}m InGaAsP laser diode inserted into the fiber laser cavity. End pumping a 7-m-long Er{sup 3+}-doped fiber yields an output power of 1 mW for an absorbed pump power of 60 mW and a slope efficiency of 6.25%.

  11. Treatment of Gingival Hyperpigmentation by Diode Laser for Esthetical Purposes

    Directory of Open Access Journals (Sweden)

    Hanaa M. El Shenawy

    2015-08-01

    Full Text Available BACKGROUND: Gingival hyperpigmentation is a common esthetical concern in patients with gummy smile or excessive gingival display. Laser ablation has been recognized recently as the most effective, pleasant and reliable technique. It has the advantage of easy handling, short treatment time, hemostasis, decontamination, and sterilization effect. AIM: In the present study we wanted to explore the efficacy of a 980 nm wavelength diode laser in gingival depigmentation clinically by using both VAS and digital imaging method as means of assessment. METHODS: Diode laser ablation was done for 15 patients who requested cosmetic therapy for melanin pigmented gums. The laser beam delivered by fiberoptic with a diameter of 320 µm, the diode laser system has 980 nm wave lengths and 3 W irradiation powers, in a continuous contact mode in all cases, the entire surface of each pigmented maxillary and mandibular gingiva that required treatment was irradiated in a single session. Clinical examination and digital image analysis were done and the patients were followed up for 3 successive months. RESULTS: There was a statistically significant change in prevalence of bleeding after treatment, as none of the cases showed any signs of bleeding 1 week, 1 month and 3 months after ablation. No statistically significant change was observed in the prevalence of swelling after treatment The VAS evaluation demonstrated that only 4 patients complained of mild pain immediately after the procedure. No pain was perceived from the patients in the rest of the follow up period. There was no statistically significant change in prevalence of pain immediately after treatment compared to pain during treatment. There was a decrease in cases with mild pain after 1 week, 1 month as well as 3 months compared to pain during treatment and immediately after treatment. CONCLUSION: Within the limitations of this study, the use of diode laser was shown to be a safe and effective treatment

  12. Highly-reliable laser diodes and modules for spaceborne applications

    Science.gov (United States)

    Deichsel, E.

    2017-11-01

    Laser applications become more and more interesting in contemporary missions such as earth observations or optical communication in space. One of these applications is light detection and ranging (LIDAR), which comprises huge scientific potential in future missions. The Nd:YAG solid-state laser of such a LIDAR system is optically pumped using 808nm emitting pump sources based on semiconductor laser-diodes in quasi-continuous wave (qcw) operation. Therefore reliable and efficient laser diodes with increased output powers are an important requirement for a spaceborne LIDAR-system. In the past, many tests were performed regarding the performance and life-time of such laser-diodes. There were also studies for spaceborne applications, but a test with long operation times at high powers and statistical relevance is pending. Other applications, such as science packages (e.g. Raman-spectroscopy) on planetary rovers require also reliable high-power light sources. Typically fiber-coupled laser diode modules are used for such applications. Besides high reliability and life-time, designs compatible to the harsh environmental conditions must be taken in account. Mechanical loads, such as shock or strong vibration are expected due to take-off or landing procedures. Many temperature cycles with high change rates and differences must be taken in account due to sun-shadow effects in planetary orbits. Cosmic radiation has strong impact on optical components and must also be taken in account. Last, a hermetic sealing must be considered, since vacuum can have disadvantageous effects on optoelectronics components.

  13. Atomic-resolution measurements with a new tunable diode laser-based interferometer

    DEFF Research Database (Denmark)

    Silver, R.M.; Zou, H.; Gonda, S.

    2004-01-01

    We develop a new implementation of a Michelson interferometer designed to make measurements with an uncertainty of less than 20 pm. This new method uses a tunable diode laser as the light source, with the diode laser wavelength continuously tuned to fix the number of fringes in the measured optical...... laser Michelson interferometer....... path. The diode laser frequency is measured by beating against a reference laser. High-speed, accurate frequency measurements of the beat frequency signal enables the diode laser wavelength to be measured with nominally 20-pm accuracy for the measurements described. The new interferometer design...

  14. Present state of applying diode laser in Toyota Motor Corp.

    Science.gov (United States)

    Terada, Masaki; Nakamura, Hideo

    2003-03-01

    Since the mid-1980s, Toyota Motor Corporation has applied CO2 lasers and YAG lasers to machine (welding, piercing, cutting, surface modifying etc.) automobile parts. In recent years diode lasers, which are excellent in terms of cost performance, are now available on the market as a new type of oscillator and are expected to bring about a new age in laser technology. Two current problems with these lasers, however, are the lack of sufficient output and the difficulty in improving the focusing the beam, which is why it has not been easy to apply them to the machining of metal parts in the past. On the other hand, plastics can be joined with low energy because they have a lower melting point than metal and the rate of absorption of the laser is easy to control. Moreover, because the high degree of freedom in molding plastic parts results in many complex shapes that need to be welded, Toyota is looking into the use of diode lasers to weld plastic parts. This article will introduce the problems of plastics welding and the methods to solve them referring to actual examples.

  15. Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

    Science.gov (United States)

    Reinl, S.

    Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

  16. Optical pumping of Rb by Ti:Sa laser and high-power laser diode

    Czech Academy of Sciences Publication Activity Database

    Buchta, Zdeněk; Rychnovský, Jan; Lazar, Josef

    2006-01-01

    Roč. 8, č. 1 (2006), s. 350-354 ISSN 1454-4164 R&D Projects: GA AV ČR IAA1065303; GA ČR GA102/04/2109 Institutional research plan: CEZ:AV0Z20650511 Keywords : optical pumping * Ti:Sa laser * laser diode * emission linewidth * spectroscopy * laser frequency stabilization Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.106, year: 2006

  17. High temperature semiconductor diode laser pumps for high energy laser applications

    Science.gov (United States)

    Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

    2018-02-01

    Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.

  18. Equipment for Diode Laser Pumping of New and Improved Optical Materials

    National Research Council Canada - National Science Library

    Jenssen, H

    1999-01-01

    .... Experiments using laser diodes as the pump source are essential for a complete characterization of these materials, which exploit the advantages of diode-pumping, leading potentially to compact...

  19. Diode laser photocoagulation in PHACES syndrome hemangiomas: a case series

    Science.gov (United States)

    Romeo, U.; Russo, N.; Polimeni, A.; Favia, G.; Lacaita, M. G.; Limongelli, L.; Franco, S.

    2014-01-01

    PHACES syndrome is a pediatric syndrome with cutaneous and extra-cutaneous manifestations, such as Posterior fossa defects, Hemangiomas, Arterial lesions, Cardiac abnormalities/aortic coarctation, Eye abnormalities and Sternal cleft. Facial hemangiomas affect the 75% of patients and may arise on the oral mucosa or perioral cutaneous regions. In this study we treated 26 Intraoral Haemangiomas (IH) and 15 Perioral Haemangiomas (PH) with diode laser photocoagulation using a laser of 800+/-10nm of wavelength. For IH treatment an optical fiber of 320 μm was used, and the laser power was set ted at 4 W (t-on 200 ms / t-off 400ms; fluence: 995 J/cm2). For PH treatment an optical fiber of 400 μm at the power of 5 W was used (t-on 100 ms / t-off 300 ms; fluence: 398 J/cm2). IH healed after one session (31%), the other (69%) after two sessions of Laser therapy. In each session, only a limited area of the PH was treated, obtaining a progressive improvement of the lesion. Diode laser photocoagulation is an effective option of treatment for IH and PH in patients affected by PHACE because of its minimal invasiveness. Moreover laser photocoagulation doesn't have side effects and can be performed repeatedly without cumulative toxicity. Nevertheless, more studies are required to evaluate the effectiveness of the therapy in mid and long time period.

  20. The study of laser beam riding guided system based on 980nm diode laser

    Science.gov (United States)

    Qu, Zhou; Xu, Haifeng; Sui, Xin; Yang, Kun

    2015-10-01

    With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

  1. Phosphor converted laser diode light source for endoscopic diagnostics

    DEFF Research Database (Denmark)

    Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

    2017-01-01

    In order to provide light sources for endourology and on-site testing of the light source, we are developing a portable endoscope light source prototype based on a phosphor converted laser diode. A small emitting area from the phosphor material excited by a laser diode enables coupling...... of the generated white light into thin optical fibres. The development involves designing optics for optimizing the light extraction efficiency and guiding of light to the area of interest. In this paper we compared the developed light source to the current standard in endoscopy – xenon arc lamps. Detailed...... spectral analysis of illuminance, CRI and CCT at two power levels and two distances for both the PC-LD and the xenon light source was performed. The obtained results verified that the developed light source is suitable for endoscopy illumination and the first pre-clinical trials will be performed shortly....

  2. V-shaped resonators for addition of broad-area laser diode arrays

    Science.gov (United States)

    Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

    2012-12-25

    A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

  3. Fungal testing of diode laser collimators

    Science.gov (United States)

    de Lourdes Quinta, Maria; Freitas, Jose C. A.; Rodrigues, Fernando C.; Silva, Jeronimo A.

    1991-03-01

    The utilization of laser systems in adverse environment conditions imposes several project restrictions. In our application, the design of laser collimators was developed according not only with the specified optical, mechanical and electronic parameters, but also, taking into account the specific environment characteristics in which the equipment was to be used, namely, climate, physical elements and biological agents. The utilization of several kinds of materials, like silicone, rubber, PVC, nitro-cellulose lacquers and oil varnishes, may facilitate the attack by fungi and in some special cases by bacteria in humid environments. In this paper the behavior of laser collimators after a severe essay with optimal conditions of humidity and temperature appropriated to growth of fungi is described.

  4. Biostimulation using an 810nm Diode Laser - A Case Series

    Directory of Open Access Journals (Sweden)

    Naseem Joy Garg

    2013-01-01

    Full Text Available A decrease in orthodontic treatment time is not only a demand by the esthetically concerned patient but is also the duty of every orthodontist. With the advent of 810 nm diode laser it could be made possible. This article presents a case series wherein use of 810 nm has been used to biostimulate the tissues and thereby resulting in increased rate of tooth movement appreciated by amount of clinically detected space closure.

  5. Antibacterial Effectiveness Of Low Energy Diode Laser Irradiation

    OpenAIRE

    Howida M. Sharaf *, Adel M. Elkhodary**, Ali E. Saafan***, Mostafa I. Mostafa

    2012-01-01

    Background: With the poor oral hygiene exhibited by patients with Down syndrome, the potential for a robust flora arises causing Periodontitis. Along with periodontal disease, the patient population has other medical conditions that limit treatment. This study was conducted to evaluate the antibacterial effectiveness of an 870-nm diode laser on periodontitis in patients with Down syndrome. Subjects & methods :Thirty five patients with Down syndrome suffering from p...

  6. Noise equivalent circuit of a semiconductor laser diode

    Science.gov (United States)

    Harder, C.; Margalit, S.; Yariv, A.; Katz, J.; Shacham, J.

    1982-01-01

    A small-signal model of a semiconductor laser is extended to include the effects of intrinsic noise by adding current and voltage noise sources. The current noise source represents the shot noise of carrier recombination, while the voltage noise source represents the random process of simulated emission. The usefulness of the noise equivalent circuit is demonstrated by calculating the modulation and noise characteristics of a current-driven diode as a function of bias current and frequency.

  7. WDM Nanoscale Laser Diodes for Si Photonic Interconnects

    Science.gov (United States)

    2016-07-25

    formed on silicon platforms, such as SiN on SiO2, or other materials. The VCSEL also has key features needed for high speed, including low thermal...mounting on silicon . The nanoscale VCSELs can achieve small optical modes and present a compact laser diode that is also robust. In this work we have used...Report Title The goal of this work has been to develop nanoscale VCSELs for integration into various optical systems, including for mounting on silicon

  8. Compact tunable mid-infrared laser source by difference frequency generation of two diode-lasers

    Science.gov (United States)

    Schade, W.; Blanke, T.; Willer, U.; Rempel, C.

    1996-07-01

    Two continuous-wave single mode diode-lasers (Hitachi HL 7851G and Toshiba TOLD 9150) are applied as signal and pump sources for difference frequency generation (DFG) in an AgGaS2 crystal with a length of 30 mm. For 90° type I phase matching tunable mid-infrared laser radiation around 5 µm is obtained with an output power of up to P DFG = 0.2 µW while the diode lasers are operated with powers of 30 and 50 mW at the center wavelengths 682 and 791 nm, respectively. The performance of the diode-laser-DFG system is shown as the absorption spectrum of CO for the P(28) rotational line around 2023 cm-1 is probed in a 10cm long cell and in the exhaust of an engine.

  9. Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

    Directory of Open Access Journals (Sweden)

    Rebeca Illescas-Montes

    2017-07-01

    Full Text Available Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm2 using different transmission modes (continuous or pulsed. The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm2; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing.

  10. Cultured Human Fibroblast Biostimulation Using a 940 nm Diode Laser

    Science.gov (United States)

    Illescas-Montes, Rebeca; Melguizo-Rodríguez, Lucía; Manzano-Moreno, Francisco Javier; García-Martínez, Olga; Ruiz, Concepción

    2017-01-01

    Background: Fibroblasts are the main cells involved in regeneration during wound healing. The objective was to determine the effect of 940 nm diode laser on cultured human fibroblasts using different irradiation regimens. Methods: The CCD-1064Sk human epithelial fibroblast cell line was treated with a 940 nm diode laser at different energy doses (power: 0.2–1 W and energy density: 1–7 J/cm2) using different transmission modes (continuous or pulsed). The effect on cell growth at 24 and 72 h post-treatment was examined by measuring the proliferative capacity, the impact on the cell cycle, and the effect on cell differentiation. Results: fibroblast proliferative capacity was increased at 24 and 72 h post-treatment as a function of the energy dose. The greatest increase was observed with a power of 0.2 or 0.5 W and energy density between 1 and 4 J/cm2; no difference was observed between continuous and pulsed modes. There were no significant differences in cell cycle between treated groups and controls. α-actin expression was increased by treatment, indicating enhanced cell differentiation. Conclusion: The 940 nm diode laser has biostimulating effects on fibroblasts, stimulating proliferative capacity and cell differentiation without altering the cell cycle. Further researches are necessary to explore its potential clinical usefulness in wound healing. PMID:28773152

  11. Quantitative fluorescein angiography following diode laser retinal photocoagulation.

    Science.gov (United States)

    Mordon, S; Desmettre, T; Devoisselle, J M

    1999-01-01

    An in vivo study was done to establish if laser-induced damage of the retina could be quantified using fluorescein angiography. This study was carried out on rabbit eyes (n = 6) with an 810 nm diode laser (spot diameter: 500 microm, pulse duration: 1 second, power: 100 mW-400 mW) adapted on a slit lamp. Fluorescence measurements were performed with a fundus camera connected to a fluorescence imaging system. Fluorescence staining of the retina was evaluated by mathematical modeling. Lesions were correlated to laser parameters and to histologic data. Image analysis shows that the laser lesions stained progressively. Fluorescence appears first at the borders of the lesion exhibiting a fluorescent ring. A progressive increase of the fluorescence into the central zone is observed. The maximum fluorescence intensity into the center of the laser spot is obtained after a delay depending on the laser energy. Below 100 +/- 20 mW, lesions are detectable by fluorescence imaging only. A fluorescence plateau appears for a threshold light dose above 200 +/- 20 mW. Mathematical modeling demonstrates that quantitative assessment of laser-induced damage to the retina is feasible using fluorescence imaging. The quantification of fluorescence staining in terms of both intensity and time can contribute to a better quantification of laser-induced damage. At last, since laser damage may mimic naturally occurring pathology, this method should also be considered to quantify different types of lesions.

  12. Future prospects of laser diodes and fiber lasers

    International Nuclear Information System (INIS)

    Ueda, Ken-ichi

    2000-01-01

    For the next century we should develop new concepts for coherent control of light generation and propagation. Owing to the recent development of ultra fine structures in semiconductor lasers, fiber lasers, and various kinds of waveguide structure, we can make optical devices which control the light propagation artificially. But, the phase locking and phase control of multiple laser oscillators are one of the most important directions of laser science and technology. The coherent summation has been a dream of laser since 1960. Is it possible to solve this old and quite challenging problem for laser science? This is also a very basic concept because the laser action based on the stimulated emission is the process of coherent summation of huge number of photons emitted from individual atoms. In this paper, I discuss the fundamental direction of laser research in the next ten or twenty years. The active optics and laser technology should be combined intrinsically in near future. (author)

  13. Benefits of quantum well intermixing in high power diode lasers

    Science.gov (United States)

    Najda, Stephen P.; Bacchin, Gianluca; Qiu, Bocang; Liu, Xuefeng; Kowalski, Olek P.; Silver, Mark; McDougall, Stewart D.; Hamilton, Craig J.; Marsh, John H.

    2004-05-01

    Quantum well intermixing (QWI) can bring considerable benefits to the reliability and performance of high power laser diodes by intermixing the facet regions of the device to increase the band-gap and hence eliminate absorption, avoiding catastrophic optical damage (COD). The non-absorbing mirror (NAM) regions of the laser cavity can be up to ~20% of the cavity length, giving an additional benefit on cleave tolerances, to fabricate very large element arrays of high power, individually addressable, single mode lasers. As a consequence, large arrays of single mode lasers can bring additional benefits for packaging in terms of hybrization and integration into an optics system. Our QWI techniques have been applied to a range of material systems, including GaAs/AlGaAs, (Al)GaAsP/AlGaAs and InGaAs/GaAs.

  14. Laser cooling of beryllium ions using a frequency-doubled 626 nm diode laser.

    Science.gov (United States)

    Cozijn, F M J; Biesheuvel, J; Flores, A S; Ubachs, W; Blume, G; Wicht, A; Paschke, K; Erbert, G; Koelemeij, J C J

    2013-07-01

    We demonstrate laser cooling of trapped beryllium ions at 313 nm using a frequency-doubled extended cavity diode laser operated at 626 nm, obtained by cooling a ridge waveguide diode laser chip to -31°C. Up to 32 mW of narrowband 626 nm laser radiation is obtained. After passage through an optical isolator and beam shaping optics, 14 mW of 626 nm power remains of which 70% is coupled into an external enhancement cavity containing a nonlinear crystal for second-harmonic generation. We produce up to 35 μW of 313 nm radiation, which is subsequently used to laser cool and detect 6×10(2) beryllium ions, stored in a linear Paul trap, to a temperature of about 10 mK, as evidenced by the formation of Coulomb crystals. Our setup offers a simple and affordable alternative for Doppler cooling, optical pumping, and detection to presently used laser systems.

  15. A smile insensitive method for spectral linewidth narrowing on high power laser diode arrays

    Science.gov (United States)

    Yang, Zining; Wang, Hongyan; Li, Yuandong; Lu, Qisheng; Hua, Weihong; Xu, Xiaojun; Chen, Jinbao

    2011-10-01

    To eliminate the smile effect in spectral linewidth narrowing on high power laser diode arrays, we have introduced a plane reflective mirror into a common Littrow configuration external cavity to enhance the correlation among emitters. By this way, we obtained uniform spectral distribution among emitters of a 64-elements laser diode array with 35 GHz linewidth and 41 W output laser power.

  16. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  17. Diode-side-pumped monolithic Nd:YAG slab laser

    Science.gov (United States)

    Šulc, Jan; Jelínek, Michal; Kubeček, Václav; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2017-05-01

    Compact, high-efficient, side-pumped monolithic Nd:YAG slab laser is presented. Designed active crystal shape ensures four internal reflections of generated laser radiation forming a ring resonator with high gain. A horizontal projection of the active medium form was a isosceles trapezoid with 18.6 mm long base, and 5 mm height. The angels between long base and legs are 87 deg. The thickness of the slab was 4 mm. Both base-sides and one leg-side was high reflective for lasing radiation. Second leg-side was partially reflective for lasing radiation and serves as an output coupler. The longer base-side was highly transparent for pumping radiation. The opposite base-side was highly reflecting for pump. To increase the pump absorption efficiency Nd-doping concentration was 1.4 % Nd/Y. As a pump source, single-bar quasi-cw fast-axis collimated laser diode JOLD-180-QPFN (Jenoptik) with peak power 180 W at 808 nm and output beam 10 0.9 mm without any further optics was used for slab side-pumping. The pumping pulses with repetition rate 5 Hz were 250 μs long (maximum pump energy 39 mJ). The Nd:YAG laser was operated at 1.06 µm. Two external mirrors (one totally reflecting, second with reflectivity 80 % at 1.06 μm) were used to form the oscillator. The laser was tested in the free-running regime. The maximum laser output energy reached was 5.9 mJ which corresponds to optical-to-optical efficiency of 15 %. The laser slope efficiency in respect to laser diode output was 20 %. The divergence of multimode output beam was 7 × 2.5mrad.

  18. Optical bistability controlling light with light

    CERN Document Server

    Gibbs, Hyatt

    1985-01-01

    Optical Bistability: Controlling Light with Light focuses on optical bistability in nonlinear optical systems. Emphasis is on passive (non-laser) systems that exhibit reversible bistability with input intensity as the hysteresis variable, along with the physics and the potential applications of such systems for nonlinear optical signal processing. This book consists of seven chapters and begins with a historical overview of optical bistability in lasers and passive systems. The next chapter describes steady-state theories of optical bistability, including the Bonifacio-Lugiato model, as we

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    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....

  20. 100  J-level nanosecond pulsed diode pumped solid state laser.

    Science.gov (United States)

    Banerjee, Saumyabrata; Mason, Paul D; Ertel, Klaus; Jonathan Phillips, P; De Vido, Mariastefania; Chekhlov, Oleg; Divoky, Martin; Pilar, Jan; Smith, Jodie; Butcher, Thomas; Lintern, Andrew; Tomlinson, Steph; Shaikh, Waseem; Hooker, Chris; Lucianetti, Antonio; Hernandez-Gomez, Cristina; Mocek, Tomas; Edwards, Chris; Collier, John L

    2016-05-01

    We report on the successful demonstration of a 100 J-level, diode pumped solid state laser based on cryogenic gas cooled, multi-slab ceramic Yb:YAG amplifier technology. When operated at 175 K, the system delivered a pulse energy of 107 J at a 1 Hz repetition rate and 10 ns pulse duration, pumped by 506 J of diode energy at 940 nm, corresponding to an optical-to-optical efficiency of 21%. To the best of our knowledge, this represents the highest energy obtained from a nanosecond pulsed diode pumped solid state laser. This demonstration confirms the energy scalability of the diode pumped optical laser for experiments laser architecture.

  1. Diode-pumped all-solid-state lasers and applications

    CERN Document Server

    Parsons-Karavassilis, D

    2002-01-01

    This thesis describes research carried out by the within the Physics Department at Imperial College that was aimed at developing novel all-solid-state laser sources and investigating potential applications of this technology. A description of the development, characterisation and application of a microjoule energy level, diode-pumped all-solid-state Cr:LiSGAF femtosecond oscillator and regenerative amplifier system is presented. The femtosecond oscillator was pumped by two commercially available laser diodes and produced an approx 80 MHz pulse train of variable pulse duration with approx 30 mW average output power and a tuning range of over approx 60 nm. This laser oscillator was used to seed a regenerative amplifier, resulting in adjustable repetition rate (single pulse to 20 kHz) approx 1 mu J picosecond pulses. These pulses were compressed to approx 150 fs using a double-pass twin-grating compressor. The amplifier's performance was investigated with respect to two different laser crystals and different pul...

  2. Construction of a Visible Diode Laser Source for Free Radical Photochemistry and Spectroscopy Experiments

    Science.gov (United States)

    Newman, Bronjelyn; Halpern, Joshua B.

    1997-01-01

    Tunable diode lasers are reliable sources of narrow-band light and comparatively cheap. Optical feedback simplifies frequency tuning of the laser diodes. We are building an inexpensive diode laser system incorporating optical feedback from a diffraction grating. The external optical cavity can be used with lasers that emit between 2 and 100 mW, and will also work if they are pulsed, although this will significantly degrade the bandwidth. The diode laser output power and bandwidth are comparable to CW dye lasers used in kinetics and dynamics experiments. However, their cost and maintenance will be much less as will alignment time. We intend to use the diode lasers to investigate CN and C2 kinetics as well as to study dissociation dynamics of atmospherically important molecules.

  3. Programmable current source for diode lasers stabilized optical fiber

    International Nuclear Information System (INIS)

    Gomez, J.; Camas, J.; Garcia, L.

    2012-01-01

    In this paper, we present the electronic design of a programmable stabilized current source. User can access to the source through a password, which, it has a database with the current and voltage operating points. This source was successfully used as current source in laser diode in optical fiber sensors. Variations in the laser current were carried out by a monitoring system and a control of the Direct Current (DC), which flowing through a How land source with amplifier. The laser current can be stabilized with an error percent of ± 1 μA from the threshold current (Ith) to its maximum operation current (Imax) in DC mode. The proposed design is reliable, cheap, and its output signal of stabilized current has high quality. (Author)

  4. Diode laser supported partial nephrectomy in laparoscopic surgery: preliminary results

    Science.gov (United States)

    Sroka, Ronald; Hennig, Georg; Zillinberg, Katja; Khoder, Wael Y.

    2011-07-01

    Introduction: Warm ischemia and bleeding during laparoscopic partial nephrectomy place technical constraints on surgeons. Therefore it was the aim to develop a safe and effective laser assisted partial nephrectomy technique without need for ischemia. Patients and methods: A diode laser emitting light at 1318nm in cw mode was coupled into a bare fibre (core diameter 600 μm) thus able to transfer up to 100W to the tissue. After dry lab experience, a total of 8 patients suffering from kidney malformations underwent laparoscopic/retroperitoneoscopic partial nephrectomy. Clinically, postoperative renal function and serum c-reactive protein (CRP) were monitored. Laser induced coagulation depth and effects on resection margins were evaluated. Demographic, clinical and follow-up data are presented. Results: Overall interventions, the mean operative time was 116,5 minutes (range 60-175min) with mean blood loss of 238ml (range 50-600ml) while laser assisted resection of the kidney tissue took max 15min. After extirpation of the tumours all patients showed clinical favourable outcome during follow up period. The tumour size was measured to be 1.8 to 5cm. With respect to clinical safety and due to blood loos, two warm ischemia (19 and 24min) must be performed. Immediate postoperative serum creatinine and CRP were elevated within 0.1 to 0.6 mg/dl (mean 0.18 mg/dl) and 2.1-10 mg/dl (mean 6.24 mg/dl), respectively. The depth of the coagulation on the removed tissue ranged between <1 to 2mm without effect on histopathological evaluation of tumours or resection margin. As the surface of the remaining kidney surface was laser assisted coagulated after removal. The sealing of the surface was induced by a slightly larger coagulation margin, but could not measured so far. Conclusion: This prospective in-vivo feasibility study shows that 1318nm-diode laser assisted partial nephrectomy seems to be a safe and promising medical technique which could be provided either during open surgery

  5. Treatment of Dentine Hypersensitivity by Diode Laser: A Clinical Study

    Directory of Open Access Journals (Sweden)

    Romeo Umberto

    2012-01-01

    Full Text Available Introduction. Dentine hypersensitivity (DH is characterized by pain after stimuli that usually provoke no symptoms. This study compared the effectiveness of GaAlAs diode laser alone and with topical sodium fluoride gel (NaF. Materials and Methods. The study was conducted on 10 patients (8 F/2 M, age 25–60 and 115 teeth with DH assessed by air and tactile stimuli measured by Numeric Rating Scale (NRS. Teeth were randomly divided into G1 (34 teeth treated by 1.25% NaF; G2 (33 teeth lased at 0.5 W PW (T on 100 m and T off 100 ms, fluence 62.2 J/cm2 in defocused mode with a 320 μ fiber. Each tooth received three 1′ applications; G3 (48 teeth received NaF gel plus laser at same G2 parameters. NRS was checked at each control. Results. Significant pain reduction was showed. The NRS reduction percentages were calculated, and there was a concrete decrease of DH above all in G3 than G2 and G1. Conclusion. Diode laser is a useful device for DH treatment if used alone and mainly if used with NaF gel.

  6. Thin planar package for cooling an array of edge-emitting laser diodes

    Science.gov (United States)

    Mundinger, David C.; Benett, William J.

    1992-01-01

    A laser diode array is disclosed that includes a plurality of planar assemblies and active cooling of each assembly. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar assembly having the laser diode bar located proximate to one edge. In an array, a number of such thin planar assemblies are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink proximate to the laser diode bar to absorb heat generated by laser operation. To provide the coolant to the microchannels, each thin planar assembly comprises passageways that connect the microchannels to inlet and outlet corridors. Each inlet passageway may comprise a narrow slot that directs coolant into the microchannels and increases the velocity of flow therethrough. The corridors comprises holes extending through each of the assemblies in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has applications as an optical pump for high power solid state lasers, or by mating the diodes with fiber optic lenses. Further, the arrays can be useful in applications having space constraints and energy limitations, and in military and space applications. The arrays can be incorporated in equipment such as communications devices and active sensors.

  7. Coagulative and ablative characteristics of a novel diode laser system (1470nm) for endonasal applications

    Science.gov (United States)

    Betz, C. S.; Havel, M.; Janda, P.; Leunig, A.; Sroka, R.

    2008-02-01

    Introduction: Being practical, efficient and inexpensive, fibre guided diode laser systems are preferable over others for endonasal applications. A new medical 1470 nm diode laser system is expected to offer good ablative and coagulative tissue effects. Methods: The new 1470 nm diode laser system was compared to a conventional 940 nm system with regards to laser tissue effects (ablation, coagulation, carbonization zones) in an ex vivo setup using fresh liver and muscle tissue. The laser fibres were fixed to a computer controlled stepper motor, and the light was applied using comparable power settings and a reproducible procedure under constant conditions. Clinical efficacy and postoperative morbidity was evaluated in two groups of 10 patients undergoing laser coagulation therapy of hyperplastic nasal turbinates. Results: In the experimental setup, the 1470 nm laser diode system proved to be more efficient in inducing tissue effects with an energy factor of 2-3 for highly perfused hepatic tissue to 30 for muscular tissue. In the clinical case series, the higher efficacy of the 1470 nm diode laser system led to reduced energy settings as compared to the conventional system with comparable clinical results. Postoperative crusting was less pronounced in the 1470 nm laser group. Conclusion: The 1470 nm diode laser system offers a highly efficient alternative to conventional diode laser systems for the coagulation of hyperplastic nasal turbinates. According to the experimental results it can be furthermore expected that it disposes of an excellent surgical potential with regards to its cutting abilities.

  8. High-Power, High-Efficiency 1.907nm Diode Lasers, Phase II

    Data.gov (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...

  9. Temperature influence on diode pumped Yb:GGAG laser

    Science.gov (United States)

    Veselský, Karel; Boháček, Pavel; Šulc, Jan; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin

    2017-05-01

    We present temperature influence (in range from 78 up to 400,K) on spectroscopic properties and laser performance of new Yb-doped mixed garnet Gd3GaxAl5-xO12 (Yb:GGAG). The sample was 2.68 mm thick plane-parallel face-polished Yb:GGAG single-crystal plate which was AR coated for pump (930 nm) and generated (1030 nm) laser radiation wavelength. The composition of sample was Gd3.098Yb0:0897Ga2:41Al2.41O12 (3 at % Yb/Gd). The Yb:GGAG crystal was mounted in temperature controlled copper holder of the liquid nitrogen cryostat. The 138 mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (T > 90 % @ 930 nm, HR @ 1030 nm) placed inside cryostat, and a curved output coupler (r = 150 mm, R = 94.5 % @ 1030 nm) placed outside cryostat. For longitudinal pumping a fiber coupled laser diode was used. The diode was operating in the pulse regime (5 ms pulse length, 20 Hz repetition rate) at wavelength 928.5 nm. The absorption spectrum was measured for the temperatures from 78 to 400 K, and absorption lines narrowing was observed with temperature decrease. Zero-phonon line at 970 nm has width 1 nm (FWHM) at 100 K. The fluorescence intensity decay time was measured and it increased linearly with temperature from 864 μs @ 78 K to 881 μs @ 300 K. The temperature of active medium has strong influence mainly on laser threshold which was 5 times lower at 100 K than at 300 K, and on slope efficiency which was 3 times higher at 100 K than at 300 K.

  10. Effect of the Bit Rate on the Pulses of the Laser Diodes | Ayadi ...

    African Journals Online (AJOL)

    The qualities required for Laser Diodes are their spatial and temporal coherence, and their performance in terms modulation. This paper presents the effect data rate of optical pulses delivered by diode laser using software COMSIS. Two types of modulation have been considered: direct modulation and external modulation.

  11. Comparison of the noise performance of 10GHz QW and QD mode-locked laser diodes

    DEFF Research Database (Denmark)

    Carpintero, Guillermo; Thompson, Mark G.; Yvind, Kresten

    2010-01-01

    This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes.......This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes....

  12. Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

    Science.gov (United States)

    Maeda, Y

    1994-08-10

    An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

  13. QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

    Science.gov (United States)

    A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

  14. Portable multiwavelength laser diode source for handheld photoacoustic devices

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2016-04-01

    The ageing population faces today an increase of chronic diseases such as rheumatism/arthritis, cancer and cardio vascular diseases for which appropriate treatments based on a diagnosis at an early-stage of the disease are required. Some imaging techniques are already available in order to get structural information. Within the non-invasive group, ultrasound images are common in these fields of medicine. However, there is a need for a point-of-care device for imaging smaller structures such as blood vessels that cannot be observed with purely ultrasound based devices. Photoacoustics proved to be an attractive candidate. This novel imaging technique combines pulsed laser light for excitation of tissues and an ultrasound transducer as a receptor. Introduction of this technique into the clinic requires to drastically shrink the size and cost of the expensive and bulky nanosecond lasers generally used for light emission. In that context, demonstration of ultra-short pulse emission with highly efficient laser diodes in the near-infrared range has been performed by Quantel, France. A multi-wavelength laser source as small as a hand emitted more than 1 mJ per wavelength with four different wavelengths available in pulses of about 90 ns. Such a laser source can be integrated into high sensitivity photoacoustic handheld systems due to their outstanding electrical-to-optical efficiency of about 25 %. Further work continues to decrease the pulse length as low as 40 ns while increasing the pulse energy to 2 mJ.

  15. High power visible diode laser for the treatment of eye diseases by laser coagulation

    Science.gov (United States)

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

    2015-03-01

    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.

  16. Diode-pumped two micron solid-state lasers

    International Nuclear Information System (INIS)

    Elder, I.F.

    1997-01-01

    This thesis presents an investigation of diode-pumped two micron solid-state lasers, concentrating on a comparison of the cw room temperature operation of Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF. Dopant concentrations in YAP were 4.2% thulium and 0.28% holmium; in YLF they were 6% thulium and 0.4% holmium. Thermal modelling was carried out in order to provide an insight into the thermal lensing and population distributions in these materials. Laser operation was achieved utilising an end-pumping geometry with a simple two mirror standing wave resonator. The pump source for these experiments was a 3 W laser diode. Maximum output power was achieved with Tm:YAP, generating 730 mW of laser output, representing 42% conversion efficiency in terms of absorbed pump power. Upper bounds on the conversion efficiency of Tm,Ho:YAP and Tm,Ho:YLF laser crystal of 14% and 30% were obtained, with corresponding output powers of 270 and 660 mW. In all three cases, the output beam was TEM 00 in nature. Visible upconversion fluorescence bands in the green and red were identified in Tm,Ho:YAP and Tm,Ho:YLF, with additional blue emission from the latter, all assigned to transitions on holmium. The principal upconversion mechanisms in these materials all involved the holmium first excited state. Upconversion in Tm:YAP was negligible. The spectral output of Tm:YAP consisted of a comb of lines in the range 1.965 to 2.020 μm. For both the double-doped crystals, the laser output was multilongitudinal mode on a single transition, wavelength 2.120 μm in YAP, 2.065 μm in YLF. In the time domain the output of Tm:YAP was dominated by large amplitude spiking, unlike both of the double-doped laser crystals. The long lifetime of the thulium upper laser level (4.4 ms) provided very weak damping of the spiking. Excitation sharing between thulium and holmium, with a measured characteristic lifetime in YAP of 11.9 μs and YLF of 14.8 μs, provided strong damping of any spiking behaviour. (author)

  17. Atomic-resolution measurements with a new tunable diode laser-based interferometer

    DEFF Research Database (Denmark)

    Silver, R.M.; Zou, H.; Gonda, S.

    2004-01-01

    We develop a new implementation of a Michelson interferometer designed to make measurements with an uncertainty of less than 20 pm. This new method uses a tunable diode laser as the light source, with the diode laser wavelength continuously tuned to fix the number of fringes in the measured optical...... path. The diode laser frequency is measured by beating against a reference laser. High-speed, accurate frequency measurements of the beat frequency signal enables the diode laser wavelength to be measured with nominally 20-pm accuracy for the measurements described. The new interferometer design...... is lightweight and is mounted directly on an ultra-high vacuum scanning tunneling microscope capable of atomic resolution. We report the simultaneous acquisition of an atomic resolution image, while the relative lateral displacement of the tip along the sample distance is measured with the new tunable diode...

  18. Circular polarization switching and bistability in an optically injected 1300 nm spin-vertical cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Hurtado, A. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Institute of Photonics, Physics Department, University of Strathclyde, Wolfson Centre, 106 Rottenrow East, Glasgow G4 0NW, Scotland (United Kingdom); Korpijarvi, V.-M.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-01-12

    We report the experimental observation of circular polarization switching (PS) and polarization bistability (PB) in a 1300 nm dilute nitride spin-vertical cavity surface emitting laser (VCSEL). We demonstrate that the circularly polarized optical signal at 1300 nm can gradually or abruptly switch the polarization ellipticity of the spin-VCSEL from right-to-left circular polarization and vice versa. Moreover, different forms of PS and PB between right- and left-circular polarizations are observed by controlling the injection strength and the initial wavelength detuning. These results obtained at the telecom wavelength of 1300 nm open the door for novel uses of spin-VCSELs in polarization sensitive applications in future optical systems.

  19. Tunable diode laser spectroscopy as a technique for combustion diagnostics

    International Nuclear Information System (INIS)

    Bolshov, M.A.; Kuritsyn, Yu.A.; Romanovskii, Yu.V.

    2015-01-01

    Tunable diode laser absorption spectroscopy (TDLAS) has become a proven method of rapid gas diagnostics. In the present review an overview of the state of the art of TDL-based sensors and their applications for measurements of temperature, pressure, and species concentrations of gas components in harsh environments is given. In particular, the contemporary tunable diode laser systems, various methods of absorption detection (direct absorption measurements, wavelength modulation based phase sensitive detection), and relevant algorithms for data processing that improve accuracy and accelerate the diagnostics cycle are discussed in detail. The paper demonstrates how the recent developments of these methods and algorithms made it possible to extend the functionality of TDLAS in the tomographic imaging of combustion processes. Some prominent examples of applications of TDL-based sensors in a wide range of practical combustion aggregates, including scramjet engines and facilities, internal combustion engines, pulse detonation combustors, and coal gasifiers, are given in the final part of the review. - Highlights: • Overview of modern TDL-based sensors for combustion • TDL systems, methods of absorption detection and algorithms of data processing • Prominent examples of TDLAS diagnostics of the combustion facilities • Extension of the TDLAS on the tomographic imaging of combustion processes

  20. The advances and characteristics of high-power diode laser materials processing

    Science.gov (United States)

    Li, Lin

    2000-10-01

    This paper presents a review of the direct applications of high-power diode lasers for materials processing including soldering, surface modification (hardening, cladding, glazing and wetting modifications), welding, scribing, sheet metal bending, marking, engraving, paint stripping, powder sintering, synthesis, brazing and machining. The specific advantages and disadvantages of diode laser materials processing are compared with CO 2, Nd:YAG and excimer lasers. An effort is made to identify the fundamental differences in their beam/material interaction characteristics and materials behaviour. Also an appraisal of the future prospects of the high-power diode lasers for materials processing is given.

  1. Efficient laser-diode end-pumped Nd:GGG lasers at 1054 and 1067 nm.

    Science.gov (United States)

    Xu, Bin; Xu, Huiying; Cai, Zhiping; Camy, P; Doualan, J L; Moncorgé, R

    2014-10-10

    Efficient and compact laser-diode end-pumped Nd:GGG simultaneous multiwavelength continuous-wave lasers at ∼1059, ∼1060 and ∼1062  nm were first demonstrated in a free-running 30 mm plano-concave laser cavity. The maximum output power was up to 3.92 W with a slope efficiency of about 53.6% with respect to the absorbed pump power. By inserting a 0.1 mm optical glass plate acting as a Fabry-Pérot etalon, a single-wavelength laser at ∼1067  nm with a maximum output power of 1.95 W and a slope efficiency of 28.5% can be obtained. Multiwavelength lasers, including those at ∼1054 or ∼1067  nm, were also achievable by suitably tilting the glass etalon. These simultaneous multiwavelength lasers provide a potential source for terahertz wave generation.

  2. Demonstration of a diode-pumped metastable Ar laser.

    Science.gov (United States)

    Han, Jiande; Glebov, Leonid; Venus, George; Heaven, Michael C

    2013-12-15

    Pulsed lasing from optically pumped rare gas metastable atoms (Ne, Ar, Kr, and Xe) has been demonstrated previously. The laser relies on a three-level scheme, which involves the (n+1)p[5/2](3) and (n+1)p[1/2](1) states from the np(5)(n+1)p electronic configuration and the metastable (n+1)s[3/2](2) level of the np(5)(n+1)s configuration (Racah notation). Population inversions were achieved using relaxation from ((n+1)p[5/2](3) to (n+1)p[1/2](1) induced by collisions with helium or argon at pressures near 1 atm. Pulsed lasing was easily achieved using the high instantaneous pump intensities provided by a pulsed optical parametric oscillator excitation laser. In the present study we examine the potential for the development of a continuous wave (CW) optically pumped Ar laser. We report lasing of the 4p[1/2](1)→4s[3/2](2) (912.547 nm) transition following CW diode laser excitation of the 4p[5/2](3)←4s[3/2](2) line (811.754 nm). A pulsed discharge was used to generate Ar 4s[3/2](2), and the time-resolved lasing kinetics provide insights concerning the radiative and collisional relaxation processes.

  3. Intensity and frequency stabilization of a laser diode by simultaneously controlling its temperature and current

    Science.gov (United States)

    Mu, Weiwei; Hu, Zhaohui; Wang, Jing; Zhou, Binquan

    2017-10-01

    Nuclear magnetic resonance gyroscope (NMRG) detects the angular velocity of the vehicle utilizing the interaction between the laser beam and the alkali metal atoms along with the noble gas atoms in the alkali vapor cell. In order to reach high precision inertial measurement target, semiconductor laser in NMRG should have good intensity and frequency stability. Generally, laser intensity and frequency are stabilized separately. In this paper, a new method to stabilize laser intensity and frequency simultaneously with double-loop feedback control is presented. Laser intensity is stabilized to the setpoint value by feedback control of laser diode's temperature. Laser frequency is stabilized to the Doppler absorption peak by feedback control of laser diode's current. The feedback control of current is a quick loop, hence the laser frequency stabilize quickly. The feedback control of temperature is a slow loop, hence the laser intensity stabilize slowly. With the feedback control of current and temperature, the laser intensity and frequency are stabilized finally. Additionally, the dependence of laser intensity and frequency on laser diode's current and temperature are analyzed, which contributes to choose suitable operating range for the laser diode. The advantage of our method is that the alkali vapor cell used for stabilizing laser frequency is the same one as the cell used for NMRG to operate, which helps to miniaturize the size of NMRG prototype. In an 8-hour continuous measurement, the long-term stability of laser intensity and frequency increased by two orders of magnitude and one order of magnitude respectively.

  4. High power 2 {mu}m diode-pumped Tm:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.J.; Sutton, S.B.; Honea, E.C.; Skidmore, J.A.; Emanuel, M.A.

    1996-01-01

    Using a scaleable diode end-pumping technology developed at LLNL, we have demonstrated a compact Tm:YAG laser capable of generating more than 50 W of cw 2 {mu}m laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, are discussed.

  5. High power multiple wavelength diode laser stack for DPSSL application without temperature control

    Science.gov (United States)

    Hou, Dong; Yin, Xia; Wang, Jingwei; Chen, Shi; Zhan, Yun; Li, Xiaoning; Fan, Yingmin; Liu, Xingsheng

    2018-02-01

    High power diode laser stack is widely used in pumping solid-state laser for years. Normally an integrated temperature control module is required for stabilizing the output power of solid-state laser, as the output power of the solid-state laser highly depends on the emission wavelength and the wavelength shift of diode lasers according to the temperature changes. However the temperature control module is inconvenient for this application, due to its large dimension, high electric power consumption and extra adding a complicated controlling system. Furthermore, it takes dozens of seconds to stabilize the output power when the laser system is turned on. In this work, a compact hard soldered high power conduction cooled diode laser stack with multiple wavelengths is developed for stabilizing the output power of solid-state laser in a certain temperature range. The stack consists of 5 laser bars with the pitch of 0.43mm. The peak output power of each bar in the diode laser stack reaches as much as 557W and the combined lasing wavelength spectrum profile spans 15nm. The solidstate laser, structured with multiple wavelength diode laser stacks, allows the ambient temperature change of 65°C without suddenly degrading the optical performance.

  6. Green high-power tunable external-cavity GaN diode laser at 515 nm

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...... laser system....

  7. Comparison of the effect of diode laser versus intense pulsed light in axillary hair removal.

    Science.gov (United States)

    Ormiga, Patricia; Ishida, Cleide Eiko; Boechat, Alvaro; Ramos-E-Silva, Marcia

    2014-10-01

    Devices such as diode laser and intense pulsed light (IPL) are in constant development aiming at permanent hair removal, but there are few comparative studies between these technologies. The objective was to comparatively assess axillary hair removal performed by diode laser and IPL and to obtain parameters of referred pain and evolution response for each method. A comparative prospective, double-blind, and randomized study of axillary hair removal performed by the diode laser and IPL was conducted in 21 females. Six sessions were held with application of the diode laser in one axilla and the IPL in the other, with intervals of 30 days and follow-up of 6 months after the last session. Clinical photographs and digital dermoscopy for hair counts in predefined and fixed fields of the treated areas were performed before, 2 weeks after the sixth session, and 6 months after the end of treatment. A questionnaire to assess the pain was applied. The number of hair shafts was significantly reduced with the diode laser and IPL. The diode laser was more effective, although more painful than the IPL. No serious, adverse, or permanent effects were observed with both technologies. Both diode laser and the IPL are effective, safe, and able to produce lasting results in axillary hair removal.

  8. High-power direct diode laser output by spectral beam combining

    Science.gov (United States)

    Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

    2018-03-01

    We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

  9. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    International Nuclear Information System (INIS)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL's). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL's which are appropriate for material processing applications, low and intermediate average power DPSSL's are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications

  10. Hardening and welding with high-power diode lasers

    Science.gov (United States)

    Ehlers, Bodo; Herfurth, Hans-Joachim; Heinemann, Stefan

    2000-03-01

    Commercially available high power diode lasers (HPDLs) with output powers of up to 6 kW have been recognized as an interesting tool for industrial applications. In certain fields of application they offer many advantages over Nd:YAG and CO2 lasers because of their low maintenance, compact design and low capital costs. Examples of successful industrial implementation of HPDLs include plastic welding, surface hardening and heat conduction welding of stainless steel and aluminum. The joining of plastics with an HPDL offers the advantages of producing a weld seam with high strength, high consistency and superior appearance. One example is the keyless entry system introduced with the Mercedes E-class where the microelectronic circuits are embedded in a plastic housing. Other applications include instrument panels, cell phones, headlights and tail lights. Applications in the field of surface treatment of metals profit from the HPDL's inherent line-shaped focus and the homogeneous intensity distribution across this focus. An HPDL system is used within the industry to harden rails for coordinate measurement machines. This system contains a customized zoom optic to focus the laser light onto the rails. With the addition of a temperature control, even complex shapes can be hardened with a constant depth and minimum distortion.

  11. Optical leak detection of oxygen using IR-laser diodes

    Science.gov (United States)

    Disimile, P. J.; Fox, C.; Toy, N.

    1991-01-01

    The ability to accurately measure the concentration of gaseous oxygen and its corresponding flow rate is becoming of greater importance. The technique being presented is based on the principal of light attenuation due to the absorption of radiation by the A-band of oxygen which is located in the 759-770 nm wavelength range. With an ability to measure the change in the light transmission to 0.05 percent, a sensitive optical leak detection system which has a rapid time response is possible. In this research program, the application of laser diode technology and its ability to be temperature tuned to a selected oxygen absorption spectral peak has allowed oxygen concentrations as low as 16,000 ppm to be detected.

  12. A low-temperature external cavity diode laser for broad wavelength tuning

    Science.gov (United States)

    Tobias, William G.; Rosenberg, Jason S.; Hutzler, Nicholas R.; Ni, Kang-Kuen

    2016-11-01

    We report on the design and characterization of a low-temperature external cavity diode laser (ECDL) system for broad wavelength tuning. The performance achieved with multiple diode models addresses the scarcity of commercial red laser diodes below 633 nm, which is a wavelength range relevant to the spectroscopy of many molecules and ions. Using a combination of multiple-stage thermoelectric cooling and water cooling, the operating temperature of a laser diode is lowered to -64 °C, more than 85 °C below the ambient temperature. The laser system integrates temperature and diffraction grating feedback tunability for coarse and fine wavelength adjustments, respectively. For two different diode models, single-mode operation is achieved with 38 mW output power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below their ambient temperature free-running wavelengths. The ECDL design can be used for diodes of any available wavelength, allowing individual diodes to be tuned continuously over tens of nanometers and extending the wavelength coverage of commercial laser diodes.

  13. Quantitative Detection of Combustion Species using Ultra-Violet Diode Lasers

    Science.gov (United States)

    Pilgrim, J. S.; Peterson, K. A.

    2001-01-01

    Southwest Sciences is developing a new microgravity combustion diagnostic based on UV diode lasers. The instrument will allow absolute concentration measurements of combustion species on a variety of microgravity combustion platforms including the Space Station. Our approach uses newly available room temperature UV diode lasers, thereby keeping the instrument compact, rugged and energy efficient. The feasibility of the technique was demonstrated by measurement of CH radicals in laboratory flames. Further progress in fabrication technology of UV diode lasers at shorter wavelengths and higher power will result in detection of transient species in the deeper UV. High sensitivity detection of combustion radicals is provided with wavelength modulation absorption spectroscopy.

  14. Comparison of laser diode response to pulsed electrical and radiative excitations

    International Nuclear Information System (INIS)

    Baggio, J.; Rainsant, J.M.; D'hose, C.; Lalande, P.; Musseau, O.; Leray, J.L.

    1996-01-01

    The authors have studied the electrical and optical response of two laser diodes under transient irradiation. Both diodes exhibit a positive photocurrent, which adds to the bias current, and a decrease of the optical power until extinction when dose rate is increased. Direct carrier generation in the laser cavity is a second order phenomena. The diode overall response is driven by both the substrate photocurrent and the transient conduction of current confinement regions, which decrease the net current density in the cavity and switches-off the laser emission. This behavior is in good agreement with pulsed electrical characterizations and 2D simulations

  15. [Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

    Science.gov (United States)

    Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

    2009-08-01

    The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

  16. The application of diode laser in the treatment of oral soft tissues lesions. A literature review.

    Science.gov (United States)

    Ortega-Concepción, Daniel; Cano-Durán, Jorge A; Peña-Cardelles, Juan-Francisco; Paredes-Rodríguez, Víctor-Manuel; González-Serrano, José; López-Quiles, Juan

    2017-07-01

    Since its appearance in the dental area, the laser has become a treatment of choice in the removal of lesions in the oral soft tissues, due to the numerous advantages they offer, being one of the most used currently the diode laser. The aim of this review was to determine the efficacy and predictability of diode laser as a treatment of soft tissue injuries compared to other surgical methods. A literature review of articles published in PubMed/MEDLINE, Scopus and the Cochrane Library databases between 2007 and 2017 was performed. "Diode laser", "soft tissue", "oral cavity" and "oral surgery" were employed for the search strategy. Only articles published English or Spanish were selected. The diode laser is a minimally invasive technology that offers great advantages, superior to those of the conventional scalpel, such as reduction of bleeding, inflammation and the lower probability of scars. Its effectiveness is comparable to that of other types of lasers, in addition to being an option of lower cost and greater ease of use. Its application in the soft tissues has been evaluated, being a safe and effective method for the excision of lesions like fibromas, epulis fissuratum and the accomplishment of frenectomies. The diode laser can be used with very good results for the removal of lesions in soft tissues, being used in small exophytic lesions due to their easy application, adequate coagulation, no need to suture and the slightest inflammation and pain. Key words: Diode laser, soft tissues, oral cavity, oral surgery.

  17. Diode laser pumped solid state laser. Part IV. ; Noise analysis. Handotai laser reiki kotai laser. 4. ; Noise kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, H.; Seno, T.; Tanabe, Y. (Asahi Glass Co. Ltd., Tokyo (Japan))

    1991-06-10

    Concerning the second harmonic generation(SHG) of diode laser pumped solid state laser using a nonlinear optical material, the researches are carried out to pracitically apply to the optical pickup. Therefore, the reduction of output optical noise has become the important researching subject. The theoretical and experimental analyses of noise generating mechanism were carried out for the system in which Nd;YAG as the laser diode and KTP (KTiOPO {sub 4}) as the nonlinear optical crystal were used. The following findings for the noise generating mechanism could be obtained: The competitive interaction between the polarization modes was dominant noise mechanism in the high frequency range from 1 to 20MHz and the noise could be removed sufficiently by using the QWP(quarter wave plate). On the other hand, the noise observed in the low frequency range from 100 to 200kHz depended on the resonance length, agreed qualitatively with the theoretical analysis of the noise to the competitive longitudinal modes and agreed quantitatively with the noise generating frequency range. 10 refs., 13 figs., 1 tab.

  18. Compact 2100 nm laser diode module for next-generation DIRCM

    Science.gov (United States)

    Dvinelis, Edgaras; Greibus, Mindaugas; TrinkÅ«nas, Augustinas; NaujokaitÄ--, Greta; Vizbaras, Augustinas; Vizbaras, Dominykas; Vizbaras, Kristijonas

    2017-10-01

    Compact high-power 2100 nm laser diode module for next-generation directional infrared countermeasure (DIRCM) systems is presented. Next-generation DIRCM systems require compact, light-weight and robust laser modules which could provide intense IR light emission capable of disrupting the tracking sensor of heat-seeking missile. Currently used solid-state and fiber laser solutions for mid-IR band are bulky and heavy making them difficult to implement in smaller form-factor DIRCM systems. Recent development of GaSb laser diode technology greatly improved optical output powers and efficiencies of laser diodes working in 1900 - 2450 nm band [1] while also maintaining very attractive size, weight, power consumption and cost characteristics. 2100 nm laser diode module presented in this work performance is based on high-efficiency broad emitting area GaSb laser diode technology. Each laser diode emitter is able to provide 1 W of CW output optical power with working point efficiency up to 20% at temperature of 20 °C. For output beam collimation custom designed fast-axis collimator and slow-axis collimator lenses were used. These lenses were actively aligned and attached using UV epoxy curing. Total 2 emitters stacked vertically were used in 2100 nm laser diode module. Final optical output power of the module goes up to 2 W at temperature of 20 °C. Total dimensions of the laser diode module are 35 x 25 x 16 mm (L x W x H) with a weight of 28 grams. Finally output beam is bore-sighted to mechanical axes of the module housing allowing for easy integration into next-generation DIRCM systems.

  19. Investigation into the accuracy of a proposed laser diode based multilateration machine tool calibration system

    International Nuclear Information System (INIS)

    Fletcher, S; Longstaff, A P; Myers, A

    2005-01-01

    Geometric and thermal calibration of CNC machine tools is required in modern machine shops with volumetric accuracy assessment becoming the standard machine tool qualification in many industries. Laser interferometry is a popular method of measuring the errors but this, and other alternatives, tend to be expensive, time consuming or both. This paper investigates the feasibility of using a laser diode based system that capitalises on the low cost nature of the diode to provide multiple laser sources for fast error measurement using multilateration. Laser diode module technology enables improved wavelength stability and spectral linewidth which are important factors for laser interferometry. With more than three laser sources, the set-up process can be greatly simplified while providing flexibility in the location of the laser sources improving the accuracy of the system

  20. An analysis of transient thermal properties for high power GaN-based laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Min; Kim, Seungtaek; Kang, Sung Bok; Kim, Young Jin; Jeong, Hoon; Lee, Kyeongkyun; Kim, Jongseok [Korea Institute of Industrial Technology, 35-3 Hongcheon-Ri, Ipjang-Myeon, Cheonan, Chungnam 331-825 (Korea); Lee, Sangdon; Suh, Dongsik [QSI Co., Ltd., 315-9 Cheonheung-Ri, Sungger-Eup, Cheonan, Chungnam 330-836 (Korea); Yi, Jeong Hoon; Choi, Yoonho; Jung, Seok Gu; Noh, Minsoo [LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea)

    2010-07-15

    Thermal properties of 405 nm GaN-based laser diodes were investigated by employing a transient heating response method based on the temperature dependence of diode forward voltage. Thermal resistances of materials consisting of packaged laser diodes were differentiated in transient thermal response curves at a current below threshold current. With a current above threshold current, no significant change in thermal resistances and difference between junction-up and junction-down laser diodes was observed at pulses shorter than 3 sec. From an analysis with long current injections, thermal resistance of a packaged laser diode with a junction-up bonding was {proportional_to}45 C/W which was higher than that of a junction-down bonded laser diode by {proportional_to}10 C/W. Further analyses based on parameters obtained from voltage recovery curves indicated that the time constant for cooling is directly related to the thermal resistance and thermal capacitance of a laser diode package. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Modulation of Frequency Doubled DFB-Tapered Diode Lasers for Medical Treatment

    DEFF Research Database (Denmark)

    Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

    2017-01-01

    The use of visible lasers for medical treatments is on the rise, and together with this comes higher expectations for the laser systems. For many medical treatments, such as ophthalmology, doctors require pulse on demand operation together with a complete extinction of the light between pulses. We...... have demonstrated power modulation from 0.1 Hz to 10 kHz at 532 nm with a modulation depth above 97% by wavelength detuning of the laser diode. The laser diode is a 1064 nm monolithic device with a distributed feedback (DFB) laser as the master oscillator (MO), and a tapered power amplifier (PA...

  2. Cryogenic Yb:YAG laser pumped by VBG-stabilized narrowband laser diode at 969 nm

    Czech Academy of Sciences Publication Activity Database

    Jambunathan, Venkatesan; Horáčková, Lucie; Navrátil, Petr; Lucianetti, Antonio; Mocek, Tomáš

    2016-01-01

    Roč. 128, č. 12 (2016), s. 1328-1331 ISSN 1041-1135 R&D Projects: GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : Diode-pumped * cryogenic * volume Bragg grating * Yb doped * solid state lasers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.375, year: 2016

  3. Kilowatt average power 100 J-level diode pumped solid state laser

    Czech Academy of Sciences Publication Activity Database

    Mason, P.; Divoký, Martin; Ertel, K.; Pilař, Jan; Butcher, T.; Hanuš, Martin; Banerjee, S.; Phillips, J.; Smith, J.; De Vido, M.; Lucianetti, Antonio; Hernandez-Gomez, C.; Edwards, C.; Mocek, Tomáš; Collier, J.

    2017-01-01

    Roč. 4, č. 4 (2017), s. 438-439 ISSN 2334-2536 R&D Projects: GA MŠk LO1602; GA MŠk LM2015086 Institutional support: RVO:68378271 Keywords : diode-pumped * solid state * laser Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 7.727, year: 2016

  4. Intensity Noise Transfer Through a Diode-pumped Titanium Sapphire Laser System

    DEFF Research Database (Denmark)

    Tawfieq, Mahmoud; Hansen, Anders Kragh; Jensen, Ole Bjarlin

    2017-01-01

    In this paper, we investigate the noise performance and transfer in a titanium sapphire (Ti:S) laser system. This system consists of a DBR tapered diode laser, which is frequency doubled in two cascaded nonlinear crystals and used to pump the Ti:S laser oscillator. This investigation includes...

  5. Influence of the laser-diode temperature on crystal absorption and ...

    Indian Academy of Sciences (India)

    Abstract. In this work, we studied the influence of heat loaded into the laser crystal in an end- pumped solid-state Nd:YVO4 high power laser. We have shown experimentally that the optimum value of the laser-diode temperature for the maximum pump power absorption by the Nd:YVO4 crystal and the maximum Nd:YVO4 ...

  6. 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

    2017-01-01

    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.

  7. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.

    2016-01-01

    Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...

  8. Comparing the effect of diode laser against acyclovir cream for the treatment of herpes labialis.

    Science.gov (United States)

    Honarmand, Marieh; Farhadmollashahi, Leila; Vosoughirahbar, Ehsan

    2017-06-01

    Recently alternative therapies such as the use of diode laser therapy have been introduced for recurrent herpes labial infection. The aim of this study was to evaluate the effectiveness of diode laser for treatment of recurrent herpes labialis. This was single-blind randomized clinical trial to evaluate the efficacy of diode laser for the treatment of recurrent herpes labial. In total, 60 patients whit recurrent herpes simplex labialis were selected and randomly divided in to three groups. 20 patients received treatment whit diode laser (at a wavelength of 870 nm, energy density 4.5 j/cm2), 20 patients were treated with acyclovir cream 5%, 20 patients received treatment with laser-off (placebo). The end point was lesions crusting. Data analyzed by Tukey HSD Test and One-way ANOVA (at a significance level of 0.05) in SPSS-20 software. The mean length of recovery time (day) in the laser, off laser, and acyclovir groups was 2.20±0.41, 4.30±1.03, and 3.4±1.142, respectively. There is a significant difference between three groups in this regard ( P diode laser reduced the length of recovery time and pain severity faster than treatment with acyclovir cream. Key words: Recurrent herpes labial, Acyclovir, Low level laser therapy.

  9. AlGaInN laser diode technology and systems for defence and security applications

    Science.gov (United States)

    Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lujca; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

    2015-10-01

    AlGaInN laser diodes is an emerging technology for defence and security applications such as underwater communications and sensing, atomic clocks and quantum information. 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. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries. Ridge waveguide laser diodes are fabricated to achieve single mode operation with optical powers up to 100mW with the 400-440nm wavelength range with high reliability. Visible free-space and underwater communication at frequencies up to 2.5GHz is reported using a directly modulated 422nm GaN laser diode. Low defectivity and highly uniform GaN substrates allow arrays and bars to be fabricated. High power operation operation of AlGaInN laser bars with up to 20 emitters have been demonstrated at optical powers up to 4W in a CS package with common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space or optical fibre system integration with a very small form-factor.

  10. 700 W blue fiber-coupled diode-laser emitting at 450 nm

    Science.gov (United States)

    Balck, A.; Baumann, M.; Malchus, J.; Chacko, R. V.; Marfels, S.; Witte, U.; Dinakaran, D.; Ocylok, S.; Weinbach, M.; Bachert, C.; Kösters, A.; Krause, V.; König, H.; Lell, A.; Stojetz, B.; Löffler, A.; Strauss, U.

    2018-02-01

    A high-power blue laser source was long-awaited for processing materials with low absorption in the near infrared (NIR) spectral range like copper or gold. Due to the huge progress of GaN-based semiconductors, the performance of blue diode-lasers has made a major step forward recently. With the availability of unprecedented power levels at cw-operating blue diode-lasers emitting at 450 nm, it was possible to set up a high-power diode-laser in the blue spectral range to address these conventional laser applications and probably beyond that to establish completely new utilizations for lasers. Within the scope of the research project "BlauLas", funded within the German photonic initiative "EFFILAS" [8] by the German Federal Ministry of Education and Research (BMBF), Laserline in cooperation with OSRAM aims to realize a cw fiber-coupled diode-laser exceeding 1 kW blue laser power. In this paper the conceptual design and experimental results of a 700 W blue fiber-coupled diode-laser are presented. Initially a close look had to be taken on the mounting techniques of the semiconductors to serve the requirements of the GaN laser diodes. Early samples were used for extensive long term tests to investigate degradation processes. With first functional laser-modules we set up fiber-coupled laser-systems for further testing. Besides adaption of well-known optical concepts a main task within the development of the laser system was the selection and examination of suitable materials and assembling in order to minimize degradation and reach adequate lifetimes. We realized R&D blue lasersystems with lifetimes above 5,000 h, which enable first application experiments on processing of various materials as well as experiments on conversion to white-light.

  11. MEASUREMENT OF AMMONIA EMISSIONS FROM MECHANICALLY VENTILATED POULTRY HOUSES USING MULTIPATH TUNABLE DIODE LASER SPECTROSCOPY

    Science.gov (United States)

    Ammonia emissions from mechanically ventilated poultry operations are an important environmental concern. Open Path Tunable Diode Laser Absorption Spectroscopy has emerged as a robust real-time method for gas phase measurement of ammonia concentrations in agricultural settings. ...

  12. High-Power, High-Efficiency 1.907nm Diode Lasers, Phase I

    Data.gov (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...

  13. Preliminary Demonstration of Power Beaming With Non-Coherent Laser Diode Arrays

    National Research Council Canada - National Science Library

    Kare, Jordin

    1999-01-01

    A preliminary demonstration of free-space electric power transmission has been conducted using non-coherent laser diode arrays as the transmitter and standard silicon photovoltaic cell arrays as the receiver...

  14. Effect of 810 nm Diode Laser Therapy on the Rate of Extraction Space Closure

    Directory of Open Access Journals (Sweden)

    Naseem Joy Garg

    2014-01-01

    Conclusion: Biostimulation carried out using a 810 nm diode laser is capable of increasing the rate of extraction space closure in humans. Hence, it can be concluded that it is capable of increasing the rate of orthodontic tooth movement.

  15. Efficient generation of 509 nm light by sum-frequency mixing between two tapered diode lasers

    DEFF Research Database (Denmark)

    Tawfieq, Mahmoud; Jensen, Ole Bjarlin; Hansen, Anders Kragh

    2015-01-01

    We demonstrate a concept for visible laser sources based on sum-frequency generation of beam com- bined tapered diode lasers. In this specific case, a 1.7 W sum-frequency generated green laser at 509 nm is obtained, by frequency adding of 6.17 W from a 978 nm tapered diode laser with 8.06 W from...... a 1063 nm tapered diode laser, inside a periodically poled MgO doped lithium niobate crystal. This corresponds to an optical to optical conversion ef fi ciency of 12.1%. As an example of potential applica- tions, the generated nearly diffraction-limited green light is used for pumping a Ti:sapphire laser...

  16. Clinical comparison between the bleaching efficacy of light-emitting diode and diode laser with sodium perborate.

    Science.gov (United States)

    Koçak, Sibel; Koçak, Mustafa Murat; Sağlam, Baran Can

    2014-04-01

    The aim of this clinical study was to test the efficacy of a light-emitting diode (LED) light and a diode laser, when bleaching with sodium perborate. Thirty volunteers were selected to participate in the study. The patients were randomly divided into two groups. The initial colour of each tooth to be bleached was quantified with a spectrophotometer. In group A, sodium perborate and distilled water were mixed and placed into the pulp chamber, and the LED light was source applied. In group B, the same mixture was used, and the 810 nm diode laser was applied. The final colour of each tooth was quantified with the same spectrophotometer. Initial and final spectrophotometer values were recorded. Mann-Whitney U-test and Wicoxon tests were used to test differences between both groups. Both devices successfully whitened the teeth. No statistical difference was found between the efficacy of the LED light and the diode laser. © 2013 The Authors. Australian Endodontic Journal © 2013 Australian Society of Endodontology.

  17. Noise effects in an optical heterodyne spectrometer using tunable diode lasers

    Science.gov (United States)

    Katzberg, S. J.; Kowitz, H. R.; Rowland, C. W.

    1981-01-01

    A comparison of measured and predicted signal-to-noise ratio is made in an optical heterodyne spectrometer utilizing a tunable diode laser which exhibited excess noise. It is shown that good agreement between predicted and measured signal-to-noise ratios results if excess noise effects due to tunable diode lasers are included in the predictions. The methods used to quantify excess noise and to incorporate their effects into predictions of signal-to-noise ratio are discussed.

  18. Selective nociceptor activation in volunteers by infrared diode laser

    Directory of Open Access Journals (Sweden)

    Nemenov Mikhail I

    2011-03-01

    Full Text Available Abstract Background Two main classes of peripheral sensory neurons contribute to thermal pain sensitivity: the unmyelinated C fibers and thinly myelinated Aδ fibers. These two fiber types may differentially underlie different clinical pain states and distinctions in the efficacy of analgesic treatments. Methods of differentially testing C and Aδ thermal pain are widely used in animal experimentation, but these methods are not optimal for human volunteer and patient use. Thus, this project aimed to provide psychophysical and electrophysiological evidence that whether different protocols of infrared diode laser stimulation, which allows for direct activation of nociceptive terminals deep in the skin, could differentially activate Aδ or C fiber thermonociceptors in volunteers. Results Short (60 ms, high intensity laser pulses (SP evoked monomodal "pricking" pain which was not enhanced by topical capsaicin, whereas longer, lower power pulses (LP evoked monomodal "burning" pain which was enhanced by topical capsaicin. SP also produced cortical evoked EEG potentials consistent with Aδ mediation, the amplitude of which was directly correlated with pain intensity but was not affected by topical capsaicin. LP also produced a distinct evoked potential pattern the amplitude of which was also correlated with pain intensity, which was enhanced by topical capsaicin, and the latency of which could be used to estimate the conduction velocity of the mediating nociceptive fibers. Conclusions Psychophysical and electrophysiological data were consistent with the ability of short high intensity infrared laser pulses to selectively produce Aδ mediated pain and of longer pulses to selectively produce C fiber mediated thermal pain. Thus, the use of these or similar protocols may be useful in developing and testing novel therapeutics based on the differential molecular mechanisms underlying activation of the two fiber types (e.g., TRPV1, TRPV2, etc. In addition

  19. Laser assisted die bending: a new application of high power diode lasers

    Science.gov (United States)

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

    2015-02-01

    Nowadays high power lasers are mainly used for cutting of sheet metals, for welding, hardening and rapid prototyping. In the forming of sheet metals as bending or deep drawing lasers are not used. Nevertheless a few years ago a new application of high power lasers has been invented, where bending of materials that break at room temperature becomes possible by heating them along the bending edge with high power lasers thus allowing their treatment without cracks and rupture. For this purpose a large number of diode lasers are arranged in the bottom tool of a bending machine (a V-shaped die) which heat up the initially flat sheet metal during the bending process what is performed by pressing it into the die with a knife shaped upper tool where due to the laser heating the material is softened and thus cracks are avoided. For the technical realization of the new process of laser assisted die bending, modules equipped with numerous laser diodes and a total beam power of 2,5 kW are used. The light emitted by these modules enters a tool with a length of 15cm and is deflected towards the workpiece. By using ten of these modules with adjacent dies and by integrating those in a bending press a bending edge of sheet metals with a length of 1500mm can be realized. Such a bending press with laser assistance also needs energization with a power of practically 50kW, a respective water flow, a heat exchanger system and also a control for all functions of this system. Special measures have also been developed to avoid radiating of those tools that are not covered by a workpiece in the case of bending edges shorter than the full length of the bending tools whereas individual short circuiting of diode modules can be performed. Specific measures to ensure a safe operation without any harm to the operational person have been realized. Exploitation of the bending process has been carried out for titanium, where material thicknesses up to 3mm have been bent successfully.

  20. AlGaInN laser diode technology for defence, security and sensing applications

    Science.gov (United States)

    Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

    2014-10-01

    The latest developments in AlGaInN laser diode technology are reviewed for defence, security and sensing applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW in the 400-420nm wavelength range that are suitable for telecom applications. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Gallium-nitride (GaN) blue laser diode is reported. High power operation of AlGaInN laser diodes is demonstrated with a single chip, AlGaInN laser diode `mini-array' with a common p-contact configuration at powers up to 2.5W cw at 410nm. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. GaN laser bars of up to 5mm with 20 emitters, mounted in a CS mount package, give optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.or.

  1. GreenLight laser vs diode laser vaporization of the prostate: 3-year results of a prospective nonrandomized study.

    Science.gov (United States)

    Guo, Sanwei; Müller, Georg; Bonkat, Gernot; Püschel, Heike; Gasser, Thomas; Bachmann, Alexander; Rieken, Malte

    2015-04-01

    Laser vaporization of the prostate is one of the alternatives to transurethral resection of the prostate. Short-term studies report a comparable outcome after laser vaporization with the 532 nm 120-W GreenLight high-performance system (HPS) laser and the 980 nm 200 W high-intensity diode (diode) laser. In this study, we analyzed the intermediate-term results of both techniques. From January 2007 to January 2008, 112 consecutive patients with symptomatic benign prostate enlargement were nonrandomly assigned to treatment with the GreenLight laser or the diode laser. Perioperative parameters, postoperative functional outcome, complications, and the reoperation rate at 3 years were analyzed. Improvement of voiding symptoms (International Prostate Symptom Score, quality-of-life) and micturition parameters (maximum flow rate, postvoid residual volume) showed no significant difference between the HPS group and the diode group. A significantly higher reoperation rate was observed in the diode group in comparison to the HPS group (37.5% vs 8.9%, p=0.0003) due to obstructive necrotic tissue (16.1% vs 0%, p=0.0018), bladder neck stricture (16.1% vs 1.8%, p=0.008), and persisting or recurrent adenoma (5.4% vs 7.1%, p=0.70), respectively. Both lasers lead to comparable improvement of voiding parameters and micturition symptoms. Treatment with the 200 W diode laser led to a significantly higher reoperation rate, which might be attributed to a higher degree of coagulation necrosis. Thus, a careful clinical application of this diode laser type is warranted.

  2. Efficacy of Diode Laser for the Management of Potentially Malignant Disorders.

    Science.gov (United States)

    Reddy Kundoor, Vinay Kumar; Patimeedi, Ashwini; Roohi, Shameena; Maloth, Kotya Naik; Kesidi, Sunitha; Masabattula, Geetha Kumari

    2015-01-01

    Laser dentistry is a one of the upcoming advanced treatment modality for oral mucosal lesions. Diode laser is a soft tissue laser that has found much acceptance in all branches of dentistry. Available compact size and feasibility has render diode laser an enhanced tool for today's clinical practice. The aim of this study is to determine the efficacy and safety of diode laser for the management of white lesions such as oral leukoplakia (OL) and oral lichen planus (OLP). The study was conducted by using diode laser 980 nm on 10 patients with white lesions (5 OL and 5 OLP) aged between 35 to 65 years. Of the 10 patients (5 OL and 5 OLP), 3 patients (30%) complained of moderate pain and 7 patients (70%) complained of mild pain, for first 3 days after laser irradiation, and pain disappeared at end of first week. There was no recurrence of the lesion during the 6-month follow up. Diode lasers provide acceptable clinical improvement of potentially malignant lesions with minimal side effects. It can be considered one of the best alternative treatment modality for oral mucosal lesions.

  3. Complicações na dacriocistorrinostomia transcanalicular com laser diodo: complications Transcanalicular dacryocystorhinostomy with diode laser

    Directory of Open Access Journals (Sweden)

    Eduardo Alonso Garcia

    2009-08-01

    Full Text Available OBJETIVO: Analisar as complicações da aplicação do laser de diodo para o tratamento da obstrução nasolacrimal adquirida. MÉTODOS: Foram realizados 44 procedimentos (dacriocistorrinostomia transcanalicular com laser de diodo com intubação bicanalicular de silicone sob anestesia local entre fevereiro de 2002 a novembro de 2007 em 41 pacientes (3 bilateralmente, sendo 32 mulheres e 9 homens. RESULTADOS: As complicações mais frequentes no intraoperatório foram: dificuldade de passar a sonda de Crawford (13,6% e passagem da fibra óptica dificultada (11,3%. No pós-operatório, a epífora foi a ocorrência mais frequente (15,9%, seguida pela retirada acidental do silastic (11,3%. CONCLUSÃO: Os índices de complicações intra e pós-operatórias se equivalem aos artigos publicados com a mesma técnica cirúrgica (e mesmo tipo de laser.PURPOSE: To evaluate the complications of the use of diode laser in the treatment of acquired nasolacrimal obstruction. METHODS: Forty four procedures (transcanalicular dacryocystorhinostomy with diode laser with bicanalicular silicone tube intubation and local anesthesia where performed from February 2002 to November 2007 in 41 patients (3 bilaterally, 32 women and 9 men. RESULTS: The most common intraoperative complications were disability to pass the Crawford probe (13.6% and the laser probe (11.3%. Regarding postoperative complications, epiphora was the event of higher frequency (15.9% followed by the non-intentional silastic extrusion by the patient (11.3%. CONCLUSION: Intraoperative and postoperative complications rate were similar of others articles that demonstrated the same surgical technique (with same laser.

  4. An in vitro antifungal efficacy of silver nanoparticles activated by diode laser to Candida albicans

    Science.gov (United States)

    Astuti, S. D.; Kharisma, D. H.; Kholimatussa'diah, S.; Zaidan, A. H.

    2017-09-01

    Microbial infectious diseases and increased resistance to antibiotics become urgent problems requiring immediate solutions. One promising alternative is the using of silver nanoparticles. The combination of the microbial inhibition characteristic of silver nanotechnology enhances the activity of antimicrobial effect. This study aims to determine effectiveness of antifungal silver nanoparticles with the activation of the diode laser on Candida albicans. The samples were culture of Candida albicans. Candida albicans cultures were incubated with silver nanoparticles (concentration 10-4 M) and treated with various exposure time of diode laser (15, 30, 45, 60, 75, 90)s. The suspension was planted on Sabouraud Dextrone Agar sterile media and incubated for 24 hours at temperature of 37oC. The number of colony-forming units per milliliter (CFU/ml) was determined after incubation. The results were log-transformed and analyzed by analysis of variance (ANOVA). In this analysis, P value ≤0.05 was considered to indicate a statistically significant difference. The result of this study showed the quantum yield of silver nanoparticles with diode laser 450 nm was 63,61%. Irradiating with diode laser 450 nm for 75 s resulted in the highest decreasing percentage of Candida albicans viability 65,03%. Irradiating with diode laser 450 nm 75 s with silver nanoparticles resulted in the higest decreasing percentage of Candida albicans viability 84,63%. Therefore, silver nanoparticles activated with diode laser irradiation of 450 nm resulted antifungal effect to Candida albicans viability.

  5. Frequency locking of compact laser-diode modules at 633 nm

    Science.gov (United States)

    Nölleke, Christian; Leisching, Patrick; Blume, Gunnar; Jedrzejczyk, Daniel; Pohl, Johannes; Feise, David; Sahm, Alexander; Paschke, Katrin

    2018-02-01

    This work reports on a compact diode-laser module emitting at 633 nm. The emission frequency can be tuned with temperature and current, while optical feedback of an internal DBR grating ensures single-mode operation. The laser diode is integrated into a micro-fabricated package, which includes optics for beam shaping, a miniaturized optical isolator, and a vapor cell as frequency reference. The achieved absolute frequency stability is below 10-8 , while the output power can be more than 10 mW. This compact absolute frequency-stabilized laser system can replace gas lasers and may be integrated in future quantum technology devices.

  6. Comparison of Refractive Error Changes in Retinopathy of Prematurity Patients Treated with Diode and Red Lasers.

    Science.gov (United States)

    Roohipoor, Ramak; Karkhaneh, Reza; Riazi Esfahani, Mohammad; Alipour, Fateme; Haghighat, Mahtab; Ebrahimiadib, Nazanin; Zarei, Mohammad; Mehrdad, Ramin

    2016-01-01

    To compare refractive error changes in retinopathy of prematurity (ROP) patients treated with diode and red lasers. A randomized double-masked clinical trial was performed, and infants with threshold or prethreshold type 1 ROP were assigned to red or diode laser groups. Gestational age, birth weight, pretreatment cycloplegic refraction, time of treatment, disease stage, zone and disease severity were recorded. Patients received either red or diode laser treatment and were regularly followed up for retina assessment and refraction. The information at month 12 of corrected age was considered for comparison. One hundred and fifty eyes of 75 infants were enrolled in the study. Seventy-four eyes received diode and 76 red laser therapy. The mean gestational age and birth weight of the infants were 28.6 ± 3.2 weeks and 1,441 ± 491 g, respectively. The mean baseline refractive error was +2.3 ± 1.7 dpt. Posttreatment refraction showed a significant myopic shift (mean 2.6 ± 2.0 dpt) with significant difference between the two groups (p diode laser treatment (mean 6.00 dpt) and a lesser shift among children with zone II and red laser treatment (mean 1.12 dpt). The linear regression model, using the generalized estimating equation method, showed that the type of laser used has a significant effect on myopic shift even after adjustment for other variables. Myopic shift in laser-treated ROP patients is related to the type of laser used and the involved zone. Red laser seems to cause less myopic shift than diode laser, and those with zone I involvement have a greater myopic shift than those with ROP in zone II. © 2016 S. Karger AG, Basel.

  7. Novel 755-nm diode laser vs. conventional 755-nm scanned alexandrite laser: Side-by-side comparison pilot study for thorax and axillary hair removal.

    Science.gov (United States)

    Paasch, Uwe; Wagner, Justinus A; Paasch, Hartmut W

    2015-01-01

    Alexandrite (755 nm) and diode lasers (800-810 nm) are commonly used for hair removal. The alexandrite laser technology is somewhat cumbersome whereas new diode lasers are more robust. Recently, alexandrite-like 755 nm wavelength diodes became available. To compare the efficacy, tolerability, and subject satisfaction of a 755 nm diode laser operated in conventional (HR) and non-conventional in-motion (SHR) modes with a conventional scanned alexandrite 755 nm laser for chest and axillary hair removal. A prospective, single-center, proof of principle study was designed to evaluate the safety, efficacy and handling of a 755 nm diode laser system in comparison to a standard alexandrite 755 nm scanning hair removal laser. The new 755 nm diode is suitable to be used in SHR and HR mode and has been tested for its safety, efficacy and handling in a volunteer with success. Overall, both systems showed a high efficacy in hair reduction (88.8% 755 nm diode laser vs. 77.7% 755 nm alexandrite laser). Also, during the study period, no severe adverse effects were reported. The new 755 nm diode laser is as effective and safe as the traditional 755 nm alexandrite laser. Additionally, treatment with the 755 nm diode laser with HR and SHR modes was found to be less painful.

  8. Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes

    Science.gov (United States)

    Sugiyama, Naoto; Tanaka, Hiroki; Kannari, Fumihiko

    2018-05-01

    We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (∼450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.

  9. Theoretical study on the thermal and optical features of a diode side-pumped alkali laser

    Science.gov (United States)

    Han, Juhong; Liu, Xiaoxu; Wang, Hongyuan; Cai, He; An, Guofei; Zhang, Wei; Wang, You

    2018-03-01

    As one of the most hopeful candidates to achieve high power performances, a diode-pumped alkali laser (DPAL) has attracted a lot of attention in the last decade. Comparing with a diode end-pumped alkali laser (DEPAL), a diode side-pumped alkali laser (DSPAL) has great potentiality to realize an even-higher output of alkali lasers. However, there are few related researching studies concern DSPAL. In this paper, we introduce a theoretical model to investigate the physical features of a double-directions side-pumped alkali laser. The distributions of the population density, temperature, and absorption power at the cross section of a vapor cell are systematically studied. The analyses should be valuable for design of a steady high-powered DPAL.

  10. Analysis of localized drilling of zona pellucida by 1.48-μm diode laser

    Science.gov (United States)

    Rastegar, Sohi; Hollis, Artha J.; Descloux, Laurent; Rink, Klaus; Delacretaz, Guy P.; Senn, Alfred; Nocera, Dorotha; Germond, Marc

    1996-05-01

    Laser drilling of the zona pellucida of the mammalian egg can be achieved using a continuous wave 1.48 micrometers diode laser because of high absorption coefficient of water at this wavelength. Effect of increase in temperature of the medium on the holes produced by the laser is studied. A threshold temperature is identified and its relation to the radial temperature field in the laser irradiated zona is discussed.

  11. Modulation of distributed feedback (DFB) laser diode with the autonomous Chua's circuit: Theory and experiment

    Science.gov (United States)

    Talla Mbé, Jimmi Hervé; Woafo, Paul

    2018-03-01

    We report on a simple way to generate complex optical waveforms with very cheap and accessible equipments. The general idea consists in modulating a laser diode with an autonomous electronic oscillator, and in the case of this study, we use a distributed feedback (DFB) laser diode pumped with an electronic Chua's circuit. Based on the adiabatic P-I characteristics of the laser diode at low frequencies, we show that when the total pump is greater than the laser threshold, it is possible to convert the electrical waveforms of the Chua's circuit into optical carriers. But, if that is not the case, the on-off dynamical behavior of the laser permits to obtain many other optical waveform signals, mainly pulses. Our numerical results are consistent with experimental measurements. The work presents the advantage of extending the range of possible chaotic dynamics of the laser diodes in the time domains (millisecond) where it is not usually expected with conventional modulation techniques. Moreover, this new technique of laser diodes modulation brings a general benefit in the physical equipment, reduces their cost and congestion so that, it can constitute a step towards photonic integrated circuits.

  12. Temperature evaluation of dental implant surface irradiated with high-power diode laser.

    Science.gov (United States)

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

    2016-09-01

    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.

  13. In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser

    Science.gov (United States)

    Liu, Ying; Gao, Jie; Gao, Yan; XU, Shuaimei; Zhan, Xueling; Wu, Buling

    2013-01-01

    Introduction: To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Methods: Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm2; Group B: 2 W/CW (continuous mode), 166 J/cm2; Group C: 3W/CW, 250 J/cm2; and Group D: 4W/CW, 333 J/cm2. Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm2; and Group F: 2.0 W/CW, 166 J/cm2. The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. Results: The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusions: Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm2) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue. PMID:25606318

  14. PERFORMANCE OPTIMIZATION OF THE DIODE-PUMPED SOLID-STATE LASER FOR SPACE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    D. A. Arkhipov

    2015-11-01

    Full Text Available Subject of Research. Thermophysical and optical techniques of parameter regulation for diode pumped solid-state laser are studied as applied to space laser communication and laser ranging lines. Methods. The investigations are carried out on the base of the original design of diode pumped solid-state laser module that includes the following: Nd:YAG slab element, diode pumped by 400W QCW produced by NORTHROP GRUMMAN; two-pass unstable resonator with rotation of the laser beam aperture about its axis through 1800; the output mirror of the resonator with a variable reflection coefficient; hyperthermal conductive plates for thermal stabilization of the laser diode generation modes. The presence of thermal conductive plates excludes conventional running water systems applied as cooling systems for solid-state laser components. The diodes temperature stabilization is achieved by applying the algorithm of pulse-width modulation of power of auxiliary electric heaters. To compensate for non-stationary thermal distortions of the slab refractive index, the laser resonator scheme comprises a prism reflector with an apex angle of 1200. Narrow sides of the prism are covered with reflective coating, and its wide side is sprayed with antireflection coating. The beam aperture is turned around its axis through 1800 because of triple reflection of the beam inside the prism. The turning procedure leads to compensating for the output beam phase distortions in view of symmetric character of the aberrations of slab refractive index. To suppress parasitic oscillations inside the slab, dielectric coatings of wide sides of the slab are used. Main Results. We have demonstrated theoretically and experimentally that the usage of hyperthermal conductive plates together with the algorithm of pulse-width modulation provides stabilizing of the diode substrate temperature accurate within ± 0.1 °С and smoothing the temperature distribution along the plate surface accurate

  15. Tuneable diode laser spectroscopy correction factor investigation on ammonia measurement

    Science.gov (United States)

    Li, Nilton; El-Hamalawi, Ashraf; Baxter, Jim; Barrett, Richard; Wheatley, Andrew

    2018-01-01

    Current diesel engine aftertreatment systems, such as Selective Catalyst Reduction (SCR) use ammonia (NH3) to reduce Nitrogen Oxides (NOx) into Nitrogen (N2) and water (H2O). However, if the reaction between NH3 and NOx is unbalanced, it can lead either NH3 or NOx being released into the environment. As NH3 is classified as a dangerous compound in the environment, its accurate measurement is essential. Tuneable Diode Laser (TDL) spectroscopy is one of the methods used to measure raw emissions inside engine exhaust pipes, especially NH3. This instrument requires a real-time exhaust temperature, pressure and other interference compounds in order to adjust itself to reduce the error in NH3 readings. Most researchers believed that exhaust temperature and pressure were the most influential factors in TDL when measuring NH3 inside exhaust pipes. The aim of this paper was to quantify these interference effects on TDL when undertaking NH3 measurement. Surprisingly, the results show that pressure was the least influential factor when compared to temperature, H2O, CO2 and O2 when undertaking NH3 measurement using TDL.

  16. The effect of gallium-aluminum-arsenide 808-nm low-level laser therapy on healing of skin incisions made using a diode laser.

    Science.gov (United States)

    Güngörmüş, Metin; Akyol, Utkan

    2009-12-01

    To investigate the effect of low-level laser therapy (LLLT) on healing of skin incisions made using a diode laser in rats. Eighteen Wistar rats were used for this study. Two parallel incisions (approximately 15 mm in length) were performed on the left and right side of the dorsum of each rat using a diode laser (4-W output powers with a tip 300 microm in diameter, 6 mm long, and 635-nm aiming beam). The wound on the left side of each rat received laser stimulation (10 J/cm2) from an 808-nm-wavelength gallium-aluminum-arsenide laser (Laser Source Power 20W, Laser Class IV, Medical Class IIB, Input Power Supply 230+/-10% VAC). They were assigned to two experimental groups: Group 1, diode laser (control); Group 2, diode laser+LLLT. It was determined that there was a significant difference between the diode laser and diode laser+LLLT groups in inflammation at day 10 and a difference in reepithelization at day 20 but no significant difference in inflammation at day 20. Diode laser incision (4 W) with 10 J/cm2 LLLT seems to have a beneficial effect on skin incisions in rats. As a result, it can be concluded that wound closure was significantly enhanced with lllt on diode laser incisions in rats.

  17. Multi-kW high-brightness fiber coupled diode laser based on two dimensional stacked tailored diode bars

    Science.gov (United States)

    Bayer, Andreas; Unger, Andreas; Köhler, Bernd; Küster, Matthias; Dürsch, Sascha; Kissel, Heiko; Irwin, David A.; Bodem, Christian; Plappert, Nora; Kersten, Maik; Biesenbach, Jens

    2016-03-01

    The demand for high brightness fiber coupled diode laser devices in the multi kW power region is mainly driven by industrial applications for materials processing, like brazing, cladding and metal welding, which require a beam quality better than 30 mm x mrad and power levels above 3kW. Reliability, modularity, and cost effectiveness are key factors for success in the market. We have developed a scalable and modular diode laser architecture that fulfills these requirements through use of a simple beam shaping concept based on two dimensional stacking of tailored diode bars mounted on specially designed, tap water cooled heat sinks. The base element of the concept is a tailored diode laser bar with an epitaxial and lateral structure designed such that the desired beam quality in slow-axis direction can be realized without using sophisticated beam shaping optics. The optical design concept is based on fast-axis collimator (FAC) and slow-axis collimator (SAC) lenses followed by only one additional focusing optic for efficient coupling into a 400 μm fiber with a numerical aperture (NA) of 0.12. To fulfill the requirements of scalability and modularity, four tailored bars are populated on a reduced size, tap water cooled heat sink. The diodes on these building blocks are collimated simply via FAC and SAC. The building blocks can be stacked vertically resulting in a two-dimensional diode stack, which enables a compact design of the laser source with minimum beam path length. For a single wavelength, up to eight of these building blocks, implying a total of 32 tailored bars, can be stacked into a submodule, polarization multiplexed, and coupled into a 400 μm, 0.12NA fiber. Scalability into the multi kW region is realized by wavelength combining of replaceable submodules in the spectral range from 900 - 1100 nm. We present results of a laser source based on this architecture with an output power of more than 4 kW and a beam quality of 25 mm x mrad.

  18. In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2016-04-01

    Full Text Available Objectives: Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth.Materials and Methods: Forty human primary molars were randomly assigned to four groups (n=10. The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates.Results: The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005. There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard.Conclusion: The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

  19. Construction and characterization of external cavity diode lasers for atomic physics.

    Science.gov (United States)

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-04-24

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

  20. Intrinsic Bistability and Critical Slowing in Tm3+/Yb3+ Codoped Laser Crystal with the Photon Avalanche Mechanism

    International Nuclear Information System (INIS)

    Li, Li; Li-Xue, Chen; Xin-Lu, Zhang

    2009-01-01

    We present theoretically a novel intrinsic optical bistability (IOB) in the Tm 3+ /Yb 3+ codoped system with a photon avalanche mechanism. Numerical simulations based on the rate equation model demonstrate distinct IOB hysteresis and critical slowing dynamics around the avalanche thresholds. Such an IOB characteristic in Tm 3+ /Yb 3+ codoped crystal has potential applications in solid-state bistable optical displays and luminescence switchers in visible-infrared spectra. (fundamental areas of phenomenology (including applications))

  1. Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

    Science.gov (United States)

    Liu, Bo; Braiman, Yehuda

    2018-05-01

    We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

  2. Efficient laser performance of a cryogenic Yb:YAG laser pumped by fiber coupled 940 and 969 nm laser diodes

    Czech Academy of Sciences Publication Activity Database

    Jambunathan, Venkatesan; Miura, Taisuke; Těsnohlídková, L.; Lucianetti, Antonio; Mocek, Tomáš

    2015-01-01

    Roč. 12, č. 1 (2015), "015002-1"-"015002-6" ISSN 1612-2011 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : cryogenic lasers * absorption * bandwidth * emission cross-section * absorption cross-section * diode pump ing Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.391, year: 2015

  3. Effect of Diode Laser Irradiation Combined with Topical Fluoride on Enamel Microhardness of Primary Teeth.

    Science.gov (United States)

    Bahrololoomi, Zahra; Lotfian, Malihe

    2015-02-01

    Laser irradiation has been suggested as an adjunct to traditional caries prevention methods. But little is known about the cariostatic effect of diode laser and most studies available are on permanent teeth.The purpose of the present study was to investigate the effect of diode laser irradiation combined with topical fluoride on enamel surface microhardness. Forty-five primary teeth were used in this in vitro study. The teeth were sectioned to produce 90 slabs. The baseline Vickers microhardness number of each enamel surface was determined. The samples were randomly divided into 3 groups. Group 1: 5% NaF varnish, group 2: NaF varnish+ diode laser at 5 W power and group 3: NaF varnish+ diode laser at 7 W power. Then, the final microhardness number of each surface was again determined. The data were statistically analyzed by repeated measures ANOVA at 0.05 level of significance. In all 3 groups, microhardness number increased significantly after surface treatment (P0.05). The combined application of diode laser and topical fluoride varnish on enamel surface did not show any significant additional effect on enamel resistance to caries.

  4. Temporal measurement of MeV pulsed gamma-ray using a diode laser

    Science.gov (United States)

    Liu, Jun; Ouyang, Xiaoping; Weng, Xiufeng; Zhang, Zhongbing; Xie, Haoyu; Li, Chunhua; Ruan, Jinlu; Xu, Qing

    2018-03-01

    A single-shot temporal measurement of pulsed gamma ray using a diode laser has been carried out with the MeV gamma beams at "Qiangguang-I" facility. The gamma-ray temporal profile is encoded to the power of a diode laser by the carrier variation in laser cavity. We analyze the dynamic process of carriers induced by gamma rays and derive a sensitivity expression for the detector based on a diode laser. It shows that the sensitivity is determined by both the gain of resonant cavity and the efficiency of gamma-ray deposition in the diode laser. And the efficiency of depositing gamma-ray is estimated with Monte Carlo methods. The experimental results demonstrate that the detection method with diode lasers can be used for the temporal profile measurement of a MeV pulsed gamma ray source. The relative gamma-ray sensitivity of the detector is estimated at about 1 . 27 × 10-22 Ccm2 from the experimental results, which agrees with the theoretical predictions.

  5. Evaluation of antimicrobial and thermal effects of diode laser on root canal dentin.

    Science.gov (United States)

    Kıvanc, B H; Arısu, H D; Sağlam, B C; Akça, G; Gürel, M A; Görgül, G

    2017-12-01

    The aim of this study was to evaluate the antimicrobial effects of diode laser and temperature rise on the root surface during application. Thirty-six teeth were chemomechanically prepared and irrigated with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid, and then autoclaved and incubated with a suspension of Enterococcus faecalis. The specimens were randomly divided into three groups (n = 12): Group 1, irradiated by diode laser at 1.2 W; Group 2, irradiated by diode laser at 2 W; and Group 3, irradiated by diode laser at 3 W. The grown bacteria were counted and the mean numbers of the each test tube were determined. The temperature was measured on the external apical third of the root during laser application. The mean values of results for each group were compared using one-way analysis of variance and Tukey test. No significant difference was obtained among the test groups in terms of the colony counts (P > 0.05). According to the temperature changes, there was a significant difference between groups (P Diode laser irradiation with 1.2 W demonstrated comparable performance with 2 W and 3 W power sets for elimination of E. faecalis from root canal with less temperature rise.

  6. Effect of Diode Laser Irradiation Combined with Topical Fluoride on Enamel Microhardness of Primary Teeth.

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2015-04-01

    Full Text Available Laser irradiation has been suggested as an adjunct to traditional caries prevention methods. But little is known about the cariostatic effect of diode laser and most studies available are on permanent teeth.The purpose of the present study was to investigate the effect of diode laser irradiation combined with topical fluoride on enamel surface microhardness.Forty-five primary teeth were used in this in vitro study. The teeth were sectioned to produce 90 slabs. The baseline Vickers microhardness number of each enamel surface was determined. The samples were randomly divided into 3 groups. Group 1: 5% NaF varnish, group 2: NaF varnish+ diode laser at 5 W power and group 3: NaF varnish+ diode laser at 7 W power. Then, the final microhardness number of each surface was again determined. The data were statistically analyzed by repeated measures ANOVA at 0.05 level of significance.In all 3 groups, microhardness number increased significantly after surface treatment (P0.05.The combined application of diode laser and topical fluoride varnish on enamel surface did not show any significant additional effect on enamel resistance to caries.

  7. High-power, high-efficiency, high-brightness long-wavelength laser diodes

    Science.gov (United States)

    Patterson, Steve; Crump, Paul; Wang, Jun; Dong, Weimin; Grimshaw, Mike; Zhang, Shiguo; Elim, Sandrio; Das, Suhit; Bougher, Mike; Patterson, Jason; Kuang, Guokui; Bell, Jake; Farmer, Jason; DeVito, Mark

    2006-05-01

    Interest is rapidly growing in solid-state lasers emitting from 1500-nm to 2100-nm with applications in eye-safe range finding, LIDAR, infrared countermeasures, medicine, dentistry, and others. Traditionally, these solid-state lasers have been pumped by flash lamps or more recently, by semiconductor diode lasers. In the case of the latter, the diodes of choice have been those emitting below 1-μm. The sub-micron class of semiconductor diode lasers is highly mature and has enjoyed recent rapid advances in power and efficiency. Unfortunately, the quantum defect generated when converting to the desired wavelengths results in large amounts of excess heat generation leading to costly and heavy, expensive cooling systems and performance problems related to thermal lensing. System complexity adds further cost and weight when intermediaries, such as optical parametric oscillators, are required to reach the desired longer wavelengths. Recent advances in laser diodes emitting from 1400-nm to over 1900-nm now enable the near resonant pumping of such solid state media as Er:YAG, Ho:YAG and Cr:ZnSe. Record results in the peak output power and electrical-to-optical conversion efficiency of diode lasers emitting around 1470-nm, 1700-nm and 1900-nm are presented here.

  8. Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter

    2010-01-01

    Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...

  9. Achieving Room Temperature Orange Lasing Using InGaP/InAlGaP Diode Laser

    KAUST Repository

    Al-Jabr, Ahmad

    2015-09-28

    We demonstrated the first orange laser diode at room temperature with a decent total output power of ∼46mW and lasing wavelength of 608nm, using a novel strain-induced quantum well intermixing in InGaP/InAlGaP red laser structure.

  10. Narrow line width operation of a 980 nm gain guided tapered diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Barrientos-Barria, Jessica

    2011-01-01

    We demonstrate two different schemes for the spectral narrowing of a 12 emitter 980 nm gain guided tapered diode laser bar. In the first scheme, a reflective grating has been used in a Littman Metcalf configuration and the wavelength of the laser emission could be narrowed down from more than 5.5...

  11. All-electronic suppression of mode hopping noise in diode lasers

    DEFF Research Database (Denmark)

    Bager, L.

    1990-01-01

    A simple all-electronic stabilization scheme is presented for suppression of external-cavity mode-hopping noise in diode lasers. This excess noise is generated when the laser is subjected to optical feedback and may degrade the overall performance of optical systems including sensors. Suppression...

  12. Open-path atmospheric transmission for a diode-pumped cesium laser.

    Science.gov (United States)

    Rice, Christopher A; Lott, Gordon E; Perram, Glen P

    2012-12-01

    A tunable diode laser absorption spectroscopy device was developed to study atmospheric propagation for emerging high-energy laser weapons. The cesium diode-pumped alkali laser operates near 895 nm in the vicinity of several water-vapor absorption lines. Temperature, pressure, and water vapor concentration were determined for 150 m and 1 km open paths with statistical errors of ∼0.2%. Comparison with meteorological instruments yields agreement for the 1 km path to within 0.6% for temperature, 3.7% for pressure, and 2.4% for concentration.

  13. Realization and characterization of a stabilized power supply for a laser diode

    International Nuclear Information System (INIS)

    Houji, Imen

    2010-01-01

    This final project study is entitled realization and characterization of a stabilized power supply for a diode laser. It was developed at the National Center for Nuclear Sciences and Technology at Sidi Thabet. In a first step, we are interested on the physics of lasers and its applications in different fields. We have also focused on the electronic manufacturing of diode lasers. In a second part, we have presented in detail the current stabilized power supply and the detailed description of the various blocks of this electronic schema. Before the experimental realization, we simulated the electronic schema using the commercial software P roteus 7 . Finally we presented the practical realization of various cards.

  14. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  15. Communication with diode laser: short distance line of sight communication using fiber optics

    International Nuclear Information System (INIS)

    Mirza, A.H.

    1999-01-01

    The objective of this project is to carry audio signal from transmitting station to a short distance receiving station along line of sight and also communication through fiber optics is performed, using diode laser light as carrier. In this project optical communication system, modulation techniques, basics of laser and causes of using diode laser are discussed briefly. Transmitter circuit and receiver circuit are fully described. Communication was performed using pulse width modulation technique. Optical fiber communication have many advantages over other type of conventional communication techniques. This report contains the description of optical fiber communication and compared with other communication systems. (author)

  16. Realisation and characterization of a temperature controller for a laser diode

    International Nuclear Information System (INIS)

    Meknessi, Asma; Hafdhi, Hajer

    2010-01-01

    Our final project study focuses on the characterization and realisation of a temperature conroller for a laser diode using the proportional integral derivative (PID) servo technique. In this order, w developed and carried out two electronic cards. The first is dedicated to the PID servo. Th electronics of this card allows measurement of temperature, comparison with a user fixed temperature, the measurement of the error and finally the correction of temperature by heating or cooling the laser diode using a Peltier element. The second board is designed in order to supply the Peltier element by about 6V/3A. the first part of our work is a bibliographical research on lasers, laser diodes and their applications in the biomedical field.

  17. Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

    Science.gov (United States)

    Puri, Neerja

    2015-01-01

    Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

  18. Single-frequency diode-pumped Nd:YAG prism laser with use of a composite laser crystal

    DEFF Research Database (Denmark)

    Pedersen, Christian; Hansen, P. L.; Buchhave, Preben

    1997-01-01

    A compact, stable, diode-pumped Nd:YAG laser suitable for high-power single-frequency operation is investigated theoretically as well as experimentally. Residual spatial hole burning has been eliminated with a unidirectional ring-laser design with a specially designed intracavity prism and a comp...... and a composite YAG laser crystal. A detailed Jones matrix analysis is performed, leading to design criteria for high loss difference and high-frequency stability....

  19. Optical Bistability For Optical Signal Processing And Computing

    Science.gov (United States)

    Peyghambarian, N.; Gibbs, H. M.

    1985-02-01

    In this paper we present the basic principles of optical bistability and summarize the current advances in semiconductor optical switching, with emphasis on recent results in GaAs, CuCI, InAs, InSb, CdS, ZnS, and ZnSe etalons. These devices have great potential for applications involving optical signal processing and computing. As an example, we discuss the use of arrays of bistable devices for parallel optical processing and for addressable spatial light modulators. The use of nonlinear etalons as optical gates is also illustrated. To date, GaAs devices have shown the most favorable characteristics for practical applications. They operate at room temperature with a few milliwatts of power using a laser diode as the only light source. Quasi-cw operation and optical fiber signal regeneration have also been demonstrated. A GaAs NOR gate operates in 1 ps with <3 pJ incident energy; this, of course, implies a 1 ps switch-on time for a bistable etalon.

  20. A 1,470 nm diode laser in stapedotomy: Mechanical, thermal, and acoustic effects.

    Science.gov (United States)

    Koenraads, Simone P C; de Boorder, Tjeerd; Grolman, Wilko; Kamalski, Digna M A

    2017-08-01

    Multiple laser systems have been investigated for their use in stapes surgery in patients with otosclerosis. The diode 1,470 nm laser used in this study is an attractive laser system because it is easily transported and relatively inexpensive in use. This wavelength has relative high absorption in water. This study aimed to investigate the mechanical, thermal, and acoustic effects of the diode 1,470 nm laser on a stapes in an inner ear model. Experiments were performed in an inner ear model including fresh frozen human stapes. High-speed imaging with frame rates up to 2,000 frames per second (f/s) was used to visualize the effects in the vestibule during fenestration of the footplate. A special high-speed color Schlieren technique was used to study thermal effects. The sound produced by perforation was recorded by a hydrophone. Single pulse settings of the diode 1,470 nm laser were 100 ms, 3 W. Diode 1,470 nm laser fenestration showed mechanical effects with small vapor bubbles and pressure waves pushed into the vestibule. Thermal imaging visualized an increase temperature underneath the stapes footplate. Acoustic effects were limited, but larger sounds levels were reached when vaporization bubbles arise and explode in the vestibule. The diode 1,470 nm laser highly absorbs in perilymph and is capable of forming a clear fenestration in the stapes. An overlapping laser pulse will increase the risk of vapor bubbles, pressure waves, and heating the vestibule. As long as we do not know the possible damage of these effects to the inner ear function, it seems advisable to use the laser with less potential harm. Lasers Surg. Med. 49:619-624, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Current status of the laser diode array projector technology

    Science.gov (United States)

    Beasley, D. Brett; Saylor, Daniel A.

    1998-07-01

    This paper describes recent developments and the current status of the Laser Diode Array Projector (LDAP) Technology. The LDAP is a state-of-the-art dynamic infrared scene projector system capable of generating high resolution in-band infrared imagery at high frame rates. Three LDAPs are now operational at the U.S. Army Aviation and Missile Command's (AMCOM) Missile Research, Development, and Engineering Center (MRDEC). These projectors have been used to support multiple Hardware-in-the-Loop test entries of various seeker configurations. Seeker configurations tested include an InSb 256 X $256 focal-plane array (FPA), an InSb 512 X 512 FPA, a PtSi 640 X 480 FPA, a PtSi 256 X 256 FPA, an uncooled 320 X 240 microbolometer FPA, and two dual field- of-view (FOV) seekers. Several improvements in the projector technology have been made since we last reported in 1997. The format size has been increased to 544 X 544, and 672 X 512, and it has been proven that the LDAP can be synchronized without a signal from the unit-under test (UUT). The control software has been enhanced to provide 'point and click' control for setup, calibration, image display, image capture, and data analysis. In addition, the first long-wave infrared (LWIR) LDAP is now operational, as well as a dual field of view LDAP which can change its FOV within 0.25 seconds. The projector is interfaced to a Silicon Graphics scene generation computer which is capable of real-time 3-D scene generation. Sample images generated with the projector and captured by an InSb FPA sensor are included in the text.

  2. Controlling the emission wavelength in group III-V semiconductor laser diodes

    KAUST Repository

    Ooi, Boon S.

    2016-12-29

    Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.

  3. Stabilized diode seed laser for flight and space-based remote lidar sensing applications

    Science.gov (United States)

    McNeil, Shirley; Pandit, Pushkar; Battle, Philip; Rudd, Joe; Hovis, Floyd

    2017-08-01

    AdvR, through support of the NASA SBIR program, has developed fiber-based components and sub-systems that are routinely used on NASA's airborne missions, and is now developing an environmentally hardened, diode-based, locked wavelength, seed laser for future space-based high spectral resolution lidar applications. The seed laser source utilizes a fiber-coupled diode laser, a fiber-coupled, calibrated iodine reference module to provide an absolute wavelength reference, and an integrated, dual-element, nonlinear optical waveguide component for second harmonic generation, spectral formatting and wavelength locking. The diode laser operates over a range close to 1064.5 nm, provides for stabilization of the seed to the desired iodine transition and allows for a highly-efficient, fully-integrated seed source that is well-suited for use in airborne and space-based environments. A summary of component level environmental testing and spectral purity measurements with a seeded Nd:YAG laser will be presented. A direct-diode, wavelength-locked seed laser will reduce the overall size weight and power (SWaP) requirements of the laser transmitter, thus directly addressing the need for developing compact, efficient, lidar component technologies for use in airborne and space-based environments.

  4. Latest developments in AlGaInN laser diode technology for defence applications

    Science.gov (United States)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.

    2012-09-01

    The latest developments in AlGaInN laser diode technology is reviewed for defence applications such as underwater telecommunications, sensor systems etc. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW in the 400-420nm wavelength range with high reliability. High power operation of AlGaInN laser diodes is also reviewed. We demonstrate the operation of a single chip, high power AlGaInN laser diode 'mini-array' consisting of a 3 stripe common p-contact configuration at powers up to 2.5W cw in the 408-412 nm wavelength range. Low defectivity and highly uniform TopGaN GaN substrates allow arrays and bars of nitride lasers to be fabricated. Packaging of nitride laser diodes is substantially different compared to GaAs laser technology and new processes and techniques are required to optimize the optical power from a nitride laser bar. Laser bars of up to 5mm with 20 emitters have shown optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor. TopGaN are developing a new range of high power laser array technology over the u.v.- visible spectrum together with new packaging solutions for optical integration.

  5. Free space broad-bandwidth tunable laser diode based on Littman configuration for 3D profile measurement

    Science.gov (United States)

    Shirazi, Muhammad Faizan; Kim, Pilun; Jeon, Mansik; Kim, Chang-Seok; Kim, Jeehyun

    2018-05-01

    We developed a tunable laser diode for an optical coherence tomography system that can perform three-dimensional profile measurement using an area scanning technique. The tunable laser diode is designed using an Eagleyard tunable laser diode with a galvano filter. The Littman free space configuration is used to demonstrate laser operation. The line- and bandwidths of this source are 0.27 nm (∼110 GHz) and 43 nm, respectively, at the center wavelength of 860 nm. The output power is 20 mW at an operating current of 150 mA. A step height target is imaged using a wide-area scanning system to show the measurement accuracy of the proposed tunable laser diode. A TEM grid is also imaged to measure the topography and thickness of the sample by proposed tunable laser diode.

  6. Polarization-free Cubic Phase GaN Ultraviolet Laser Diodes for Space-based Light Interferometry

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser diodes have many advantages over other forms of lasers: extremely compact (<1cm in length), inexpensive and simple designs that can achieve high power, high...

  7. Fault-Protected Laser Diode Drivers for Improving the Performance and Lifetime of Multiple-Millisecond, Long-Pulse LDAs for NASA LIDAR Systems, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project will develop and deliver to NASA revolutionary laser diode driver technology with intelligent fault protection for driving high power laser diode...

  8. Note: Demonstration of an external-cavity diode laser system immune to current and temperature fluctuations.

    Science.gov (United States)

    Miao, Xinyu; Yin, Longfei; Zhuang, Wei; Luo, Bin; Dang, Anhong; Chen, Jingbiao; Guo, Hong

    2011-08-01

    We demonstrate an external-cavity laser system using an anti-reflection coated laser diode as gain medium with about 60 nm fluorescence spectrum, and a Rb Faraday anomalous dispersion optical filter (FADOF) as frequency-selecting element with a transmission bandwidth of 1.3 GHz. With 6.4% optical feedback, a single stable longitudinal mode is obtained with a linewidth of 69 kHz. The wavelength of this laser is operating within the center of the highest transmission peak of FADOF over a diode current range from 55 mA to 142 mA and a diode temperature range from 15 °C to 35 °C, thus it is immune to the fluctuations of current and temperature.

  9. Mathematical optimization of photovoltaic converters for diode lasers. [for spacecraft power supplies

    Science.gov (United States)

    Walker, Gilbert H.; Heinbockel, John H.

    1989-01-01

    The mathematical optimization of vertical-junction photovoltaic converters for use with diode laser arrays supplying powers up to 1 MW is discussed. Photovoltaic parameters were optimized using a mathematical model. The optimized converters have 500 single junctions connected in series. The efficiency varies from 41 percent for a 0.73-micron diode laser to 46 percent for a 0.83-micron diode laser. The optimum width of the single-junction converter is small, 3.0 microns, in order for the p-n junction to be within a diffusion length of the light-generated carriers. Another critical parameter is the series resistance; the optimum value of 0.001 ohms should be achievable. Another critical parameter is the donor carrier concentration, for which an optimum value of 5 x 10 to the 15th carriers/cu cm has been chosen.

  10. Fast random-number generation using a diode laser's frequency noise characteristic

    Science.gov (United States)

    Takamori, Hiroki; Doi, Kohei; Maehara, Shinya; Kawakami, Kohei; Sato, Takashi; Ohkawa, Masashi; Ohdaira, Yasuo

    2012-02-01

    Random numbers can be classified as either pseudo- or physical-random, in character. Pseudo-random numbers are generated by definite periodicity, so, their usefulness in cryptographic applications is somewhat limited. On the other hand, naturally-generated physical-random numbers have no calculable periodicity, thereby making them ideal for the task. Diode lasers' considerable wideband noise gives them tremendous capacity for generating physical-random numbers, at a high rate of speed. We measured a diode laser's output with a fast photo detector, and evaluated the binary-numbers from the diode laser's frequency noise characteristics. We then identified and evaluated the binary-number-line's statistical properties. We also investigate the possibility that much faster physical-random number parallel-generation is possible, using separate outputs of different optical-path length and character, which we refer to as "coherence collapse".

  11. Super fast physical-random number generation using laser diode frequency noises

    Science.gov (United States)

    Ushiki, Tetsuro; Doi, Kohei; Maehara, Shinya; Sato, Takashi; Ohkawa, Masashi; Ohdaira, Yasuo

    2011-02-01

    Random numbers can be classified as either pseudo- or physical-random in character. Pseudo-random numbers' periodicity renders them inappropriate for use in cryptographic applications, but naturally-generated physical-random numbers have no calculable periodicity, thereby making them ideally-suited to the task. The laser diode naturally produces a wideband "noise" signal that is believed to have tremendous capacity and great promise, for the rapid generation of physical-random numbers for use in cryptographic applications. We measured a laser diode's output, at a fast photo detector and generated physical-random numbers from frequency noises. We then identified and evaluated the binary-number-line's statistical properties. The result shows that physical-random number generation, at speeds as high as 40Gbps, is obtainable, using the laser diode's frequency noise characteristic.

  12. Modular microchannel cooled heatsinks for high average power laser diode arrays

    Science.gov (United States)

    Beach, Ray; Benett, William J.; Freitas, Barry L.; Mundinger, D.; Comaskey, Brian J.; Solarz, Richard W.; Emanuel, Mark A.

    1992-04-01

    Detailed performance results for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor or CW operation of fully filled laser diode arrays is made possible at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using an anisotropic chemical etching process. A modular rack-and-stack architecture is adopted for the heatsink design, allowing arbitrarily large two-dimensional arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel cooled heatsinks is ideally suited to pump array requirements for high average power crystalline lasers because of the stringent temperature demands that result from coupling the diode light to several nanometers wide absorption features characteristics of lasing ions in crystals.

  13. Microchannel-cooled heatsinks for high-average-power laser diode arrays

    Science.gov (United States)

    Benett, William J.; Freitas, Barry L.; Ciarlo, Dino R.; Beach, Raymond J.; Sutton, Steven B.; Emanuel, Mark A.; Solarz, Richard W.

    1993-11-01

    Detailed performance results for an efficient and low thermal impedance laser diode array heatsink are presented. High duty factor and even cw operation of fully filled laser diode arrays at high stacking densities are enabled at high average power. Low thermal impedance is achieved using a liquid coolant and laminar flow through microchannels. The microchannels are fabricated in silicon using an anisotropic chemical etching process. A modular rack-and- stack architecture is adopted for heatsink design, allowing arbitrarily large 2-D arrays to be fabricated and easily maintained. The excellent thermal control of the microchannel heatsinks is ideally suited to pump array requirements for high average power crystalline lasers because of the stringent temperature demands that are required to efficiently couple diode light to several-nanometer-wide absorption features characteristic of lasing ions in crystals.

  14. 760nm: a new laser diode wavelength for hair removal modules

    Science.gov (United States)

    Wölz, Martin; Zorn, Martin; Pietrzak, Agnieszka; Kindsvater, Alex; Meusel, Jens; Hülsewede, Ralf; Sebastian, Jürgen

    2015-02-01

    A new high-power semiconductor laser diode module, emitting at 760 nm is introduced. This wavelength permits optimum treatment results for fair skin individuals, as demonstrated by the use of Alexandrite lasers in dermatology. Hair removal applications benefit from the industry-standard diode laser design utilizing highly efficient, portable and light-weight construction. We show the performance of a tap-water-cooled encapsulated laser diode stack with a window for use in dermatological hand-pieces. The stack design takes into account the pulse lengths required for selectivity in heating the hair follicle vs. the skin. Super-long pulse durations place the hair removal laser between industry-standard CW and QCW applications. The new 760 nm laser diode bars are 30% fill factor devices with 1.5 mm long resonator cavities. At CW operation, these units provide 40 W of optical power at 43 A with wall-plug-efficiency greater than 50%. The maximum output power before COMD is 90 W. Lifetime measurements starting at 40 W show an optical power loss of 20% after about 3000 h. The hair removal modules are available in 1x3, 1x8 and 2x8 bar configurations.

  15. Improved low-power semiconductor diode lasers for photodynamic therapy in veterinary medicine

    Science.gov (United States)

    Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

    2001-05-01

    Cryogenically cooling semiconductor diode lasers provides higher power output, longer device lifetime, and greater monochromaticity. While these effects are well known, such improvements have not been quantified, and thus cryogenically operated semiconductor lasers have not been utilized in photodynamic therapy (PDT). We report quantification of these results from laser power meter and photospectrometer data. The emission wavelengths of these low power multiple quantum well semiconductor lasers were found to decrease and become more monochromatic with decreasing temperature. Significant power output improvements also were obtained at cryogenic temperatures. In addition, the threshold current, i.e. the current at which lasing begins, decreased with decreasing temperature. This lower threshold current combined with the increased power output produced dramatically higher device efficiencies. It is proposed that cryogenic operation of semiconductor diode lasers will reduce the number of devices needed to produce the requisite output for many veterinary and medical applications, permitting significant cost reductions.

  16. Diode laser based resonance ionization mass spectrometry for spectroscopy and trace analysis of uranium isotopes

    International Nuclear Information System (INIS)

    Hakimi, Amin

    2013-01-01

    In this doctoral thesis, the upgrade and optimization of a diode laser system for high-resolution resonance ionization mass spectrometry is described. A frequency-control system, based on a double-interferometric approach, allowing for absolute stabilization down to 1 MHz as well as frequency detunings of several GHz within a second for up to three lasers in parallel was optimized. This laser system was used for spectroscopic studies on uranium isotopes, yielding precise and unambiguous level energies, total angular momenta, hyperfine constants and isotope shifts. Furthermore, an efficient excitation scheme which can be operated with commercial diode lasers was developed. The performance of the complete laser mass spectrometer was optimized and characterized for the ultra-trace analysis of the uranium isotope 236 U, which serves as a neutron flux dosimeter and tracer for radioactive anthropogenic contaminations in the environment. Using synthetic samples, an isotope selectivity of ( 236 U)/( 238 U) = 4.5(1.5) . 10 -9 was demonstrated.

  17. AlGaAs/GaAs laser diode bars (λ = 808 nm) with improved thermal stability

    International Nuclear Information System (INIS)

    Marmalyuk, A A; Ladugin, M A; Andreev, A Yu; Telegin, K Yu; Yarotskaya, I V; Meshkov, A S; Konyaev, V P; Sapozhnikov, S M; Lebedeva, E I; Simakov, V A

    2013-01-01

    Two series of AlGaAs/GaAs laser heterostructures have been grown by metal-organic vapour phase epitaxy, and 808-nm laser diode bars fabricated from the heterostructures have been investigated. The heterostructures differed in waveguide thickness and quantum well depth. It is shown that increasing the barrier height for charge carriers in the active region has an advantageous effect on the output parameters of the laser sources in the case of the heterostructures with a narrow symmetric waveguide: the slope of their power – current characteristics increased from 0.9 to 1.05 W A -1 . Thus, the configuration with a narrow waveguide and deep quantum well is better suited for high-power laser diode bars under hindered heat removal conditions. (lasers)

  18. AlGaAs/GaAs laser diode bars (λ = 808 nm) with improved thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Marmalyuk, A A; Ladugin, M A; Andreev, A Yu; Telegin, K Yu; Yarotskaya, I V; Meshkov, A S; Konyaev, V P; Sapozhnikov, S M; Lebedeva, E I; Simakov, V A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

    2013-10-31

    Two series of AlGaAs/GaAs laser heterostructures have been grown by metal-organic vapour phase epitaxy, and 808-nm laser diode bars fabricated from the heterostructures have been investigated. The heterostructures differed in waveguide thickness and quantum well depth. It is shown that increasing the barrier height for charge carriers in the active region has an advantageous effect on the output parameters of the laser sources in the case of the heterostructures with a narrow symmetric waveguide: the slope of their power – current characteristics increased from 0.9 to 1.05 W A{sup -1}. Thus, the configuration with a narrow waveguide and deep quantum well is better suited for high-power laser diode bars under hindered heat removal conditions. (lasers)

  19. Frequency Stabilization of DFB Laser Diodes at 1572 nm for Spaceborne Lidar Measurements of CO2

    Science.gov (United States)

    Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.; Abshire, James B.; Krainak, Michael A.

    2010-01-01

    We report a fiber-based, pulsed laser seeder system that rapidly switches among 6 wavelengths across atmospheric carbon dioxide (CO2) absorption line near 1572.3 nm for measurements of global CO2 mixing ratios to 1-ppmv precision. One master DFB laser diode has been frequency-locked to the CO2 line center using a frequency modulation technique, suppressing its peak-to-peak frequency drifts to 0.3 MHz at 0.8 sec averaging time over 72 hours. Four online DFB laser diodes have been offset-locked to the master laser using phase locked loops, with virtually the same sub-MHz absolute accuracy. The 6 lasers were externally modulated and then combined to produce the measurement pulse train.

  20. 5.5 W of Diffraction-Limited Green Light Generated by SFG of Tapered Diode Lasers in a Cascade of Nonlinear Crystals

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  1. The efficiency of root canal disinfection using a diode laser: In vitro study

    Directory of Open Access Journals (Sweden)

    Anjali Kaiwar

    2013-01-01

    Full Text Available Aims: The aim of this study is to verify the disinfection of diode laser, following chemo-mechanical procedures against Enterococcus fecalis. Materials and Methods: Crowns of 30 extracted premolar teeth were sectioned at the cemento- enamel junction. The canals were shaped using step-back technique to K-file #40. The teeth were randomly assigned to three groups and placed into nutrient broth containing bacterial suspension of Enterococcus fecalis. Group A received no laser radiation. Specimens of group B and C were treated with diode laser (Sirona with energy set at 1.5 and 3 W, respectively. After laser irradiation, the teeth were placed in vials, which contained 2 mL of the nutrient broth. The vials were incubated at 37°C for 24 h. Grown colonies were identified by standard methods. Statistical Analysis Used: Statistical analysis used was the nonparametric Kruskal-Wallis test, with comparison using the Bonferroni methods of means. Results: Higher mean CFU/mL is recorded in Group A (without laser disinfection followed by Group B (with 1.5 W laser disinfection and Group C (with 3 W laser disinfection, respectively. The difference in CFU/mL between the three groups is found to be statistically significant ( P < 0.001. Conclusions: The results of this research show that the 980 nm diode laser can eliminate bacteria that has immigrated into dentin, thus being able to increase the success rate in endodontic therapy.

  2. Diode laser-assisted endoscopic dacryocystorhinostomy: a comparison of three different combinations of adjunctive procedures.

    Science.gov (United States)

    Dogan, Remzi; Meric, Aysenur; Ozsütcü, Mustafa; Yenigun, Alper

    2013-08-01

    Chronic dacryocystitis is a frequently encountered condition which can be corrected by dacryocystorhinostomy. Today, the diode laser is increasingly put to use in such corrective operations. This study aims to answer the questions of which adjunctive procedures and which combinations of such procedures are necessary and effective in securing more successful outcomes in diode laser dacryocystorhinostomy. This prospective randomized study included eighty patients (13 male, 67 female) who underwent dacryocystorhinostomy in our hospital during the 2 year period of January 2009-January 2011. The patients were selected consecutively and were randomly allocated to three groups. Group 1 (30): diode laser + mitomycin C + silicone intubation; Group 2 (27): diode laser + silicone intubation; Group 3 (23): diode laser + mitomycin C. All patients were evaluated postoperatively on day 1, week 1, and on the 1st, 3rd, 6th, 12th, 18th, and 24th months. The postoperative evaluation consisted of preoperative and postoperative ostium measurements, recording postoperative complications, and calculating and comparing success rates and operative times. The mean ages of the patients were 63.4 for Group 1, 60.7 for Group 2, and 61.8 for Group 3. No statistically significant difference was found among the groups regarding pre- and postoperative ostium measurements. The success rates were 84.3, 80, and 76.9 % for Groups 1, 2, and 3, respectively. Complications noted in Group 1 were restenosis (3), premature silicone tube loss (1), development of granulation tissue (3), synechia (2), infection (2), and hemorrhage (3). Those for Group 2 were restenosis (5), premature tube loss (2), granulation (8), synechia (6), infection (3), and hemorrhage (4). Group 3 had 6 cases with stenosis, 5 with granulation, 3 with infection, 6 with synechia, and 5 with hemorrhage. The operative times of the groups were 25.5, 15.3, and 18.1 min, respectively, for Group 1, 2, and 3. All three groups had statistically

  3. Effect of 810 nm Diode Laser Therapy on the Rate of Extraction Space Closure

    OpenAIRE

    Naseem Joy Garg; Gurkeerat Singh; Sridhar Kannan; Deepak Rai; Ankur Kaul; Ashish Gupta; Abhishek Goyalia; Gaurav Gupta

    2014-01-01

    Purpose: To determine if biostimulation using a 810 nm diode laser was capable of affecting the rate of extraction space closure during orthodontic treatment. Materials and methods: Forty dental arches of patients above 17 years of age requiring bilateral first premolar extractions were exposed to a 810 nm diode laser with a power density of 3.97 W/cm2 at 3 weeks intervals for total duration of 12 weeks during the space closure phase under direct anchorage using miniscrews. Space closure m...

  4. Compact silicon photonic wavelength-tunable laser diode with ultra-wide wavelength tuning range

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Tomohiro, E-mail: tkita@ecei.tohoku.ac.jp; Tang, Rui; Yamada, Hirohito [Graduate School of Engineering, Tohoku University, 6-6-05 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8579 (Japan)

    2015-03-16

    We present a wavelength-tunable laser diode with a 99-nm-wide wavelength tuning range. It has a compact wavelength-tunable filter with high wavelength selectivity fabricated using silicon photonics technology. The silicon photonic wavelength-tunable filter with wide wavelength tuning range was realized using two ring resonators and an asymmetric Mach-Zehnder interferometer. The wavelength-tunable laser diode fabricated by butt-joining a silicon photonic filter and semiconductor optical amplifier shows stable single-mode operation over a wide wavelength range.

  5. Compact silicon photonic wavelength-tunable laser diode with ultra-wide wavelength tuning range

    International Nuclear Information System (INIS)

    Kita, Tomohiro; Tang, Rui; Yamada, Hirohito

    2015-01-01

    We present a wavelength-tunable laser diode with a 99-nm-wide wavelength tuning range. It has a compact wavelength-tunable filter with high wavelength selectivity fabricated using silicon photonics technology. The silicon photonic wavelength-tunable filter with wide wavelength tuning range was realized using two ring resonators and an asymmetric Mach-Zehnder interferometer. The wavelength-tunable laser diode fabricated by butt-joining a silicon photonic filter and semiconductor optical amplifier shows stable single-mode operation over a wide wavelength range

  6. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    Directory of Open Access Journals (Sweden)

    G. Ledru

    2014-10-01

    Full Text Available A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y chromaticity coordinates, Correlated Color Temperature (CCT and Color Rendering Index (CRI. The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

  7. Esthetic crown lengthening with depigmentation using an 810 nm GaAlAs diode laser.

    Science.gov (United States)

    Agrawal, Amit Arvind

    2014-10-01

    Hyperpigmentation of gingiva becomes more pronounced if it is associated with "gummy smile." Correction of gummy smile and depigmentation together are key to complete patient satisfaction. An 810 nm (1.5 W, pulsed) GaAlAs diode laser was used to achieve the desired results in a 22-year-old female patient. The 6-month follow-up results showed excellent color and contour of the gingiva. Mere depigmentation without correcting gummy smile may look cosmetically good but esthetically unacceptable. Diode laser was used as it is known to be an excellent tool as compared with other conventional surgical procedures in terms of patient and operator comfort.

  8. Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

    International Nuclear Information System (INIS)

    Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

    2012-01-01

    Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

  9. A comprehensive model of catastrophic optical-damage in broad-area laser diodes

    Science.gov (United States)

    Chin, A. K.; Bertaska, R. K.; Jaspan, M. A.; Flusberg, A. M.; Swartz, S. D.; Knapczyk, M. T.; Petr, R.; Smilanski, I.; Jacob, J. H.

    2009-02-01

    The present model of formation and propagation of catastrophic optical-damage (COD), a random failure-mode in laser diodes, was formulated in 1974 and has remained substantially unchanged. We extend the model of COD phenomena, based on analytical studies involving EBIC (electron-beam induced current), STEM (scanning transmission-electron microscopy) and sophisticated optical-measurements. We have determined that a ring-cavity mode, whose presence has not been previously reported, significantly contributes to COD initiation and propagation in broad-area laser-diodes.

  10. Efficacy of diode laser (810 and 940 nm) for facial skin tightening.

    Science.gov (United States)

    Voravutinon, Nataya; Seawthaweesin, Kanikar; Bureethan, Apron; Srivipatana, Anchisa; Vejanurug, Patnapa

    2015-12-01

    Laser treatment has been introduced for facial skin tightening. However, no prior study has used a diode laser to treat facial skin laxity. To evaluate the efficacy and safety of a 810- and 940-nm diode laser (MeDioStarNeXT) for treating facial skin laxity. Thirty patients, with facial skin laxity grading scale II-IV, were enrolled in this study. Each patient underwent four sessions with a 810- and 940-nm diode laser (MeDioStarNeXT) treatment over 3-week intervals. Improvement in the laxity of facial skin was evaluated using a Cutometer MPA 580, spectrophotometer, and a grading scale. Significant improvement was observed with the Cutometer F3 and R7 parameters at 1 and 3 months after complete treatment, respectively. Physician assessment showed significant improvement in the laxity scale at 1 and 6 months after treatment. Approximately 10% of the patients reported mild pain or minor adverse events. Ninety-eight percent of the patients were satisfied with the treatments. Treatment with a diode laser (810 and 940 nm) is safe and may be effective for facial skin tightening. Maintenance treatment is necessary to sustain the effect of treatment. © 2015 Wiley Periodicals, Inc.

  11. Reversibly Bistable Flexible Electronics

    KAUST Repository

    Alfaraj, Nasir

    2015-05-01

    Introducing the notion of transformational silicon electronics has paved the way for integrating various applications with silicon-based, modern, high-performance electronic circuits that are mechanically flexible and optically semitransparent. While maintaining large-scale production and prototyping rapidity, this flexible and translucent scheme demonstrates the potential to transform conventionally stiff electronic devices into thin and foldable ones without compromising long-term performance and reliability. In this work, we report on the fabrication and characterization of reversibly bistable flexible electronic switches that utilize flexible n-channel metal-oxide-semiconductor field-effect transistors. The transistors are fabricated initially on rigid (100) silicon substrates before they are peeled off. They can be used to control flexible batches of light-emitting diodes, demonstrating both the relative ease of scaling at minimum cost and maximum reliability and the feasibility of integration. The peeled-off silicon fabric is about 25 µm thick. The fabricated devices are transferred to a reversibly bistable flexible platform through which, for example, a flexible smartphone can be wrapped around a user’s wrist and can also be set back to its original mechanical position. Buckling and cyclic bending of such host platforms brings a completely new dimension to the development of flexible electronics, especially rollable displays.

  12. Sub-100 fs high average power directly blue-diode-laser-pumped Ti:sapphire oscillator

    Science.gov (United States)

    Rohrbacher, Andreas; Markovic, Vesna; Pallmann, Wolfgang; Resan, Bojan

    2016-03-01

    Ti:sapphire oscillators are a proven technology to generate sub-100 fs (even sub-10 fs) pulses in the near infrared and are widely used in many high impact scientific fields. However, the need for a bulky, expensive and complex pump source, typically a frequency-doubled multi-watt neodymium or optically pumped semiconductor laser, represents the main obstacle to more widespread use. The recent development of blue diodes emitting over 1 W has opened up the possibility of directly diode-laser-pumped Ti:sapphire oscillators. Beside the lower cost and footprint, a direct diode pumping provides better reliability, higher efficiency and better pointing stability to name a few. The challenges that it poses are lower absorption of Ti:sapphire at available diode wavelengths and lower brightness compared to typical green pump lasers. For practical applications such as bio-medicine and nano-structuring, output powers in excess of 100 mW and sub-100 fs pulses are required. In this paper, we demonstrate a high average power directly blue-diode-laser-pumped Ti:sapphire oscillator without active cooling. The SESAM modelocking ensures reliable self-starting and robust operation. We will present two configurations emitting 460 mW in 82 fs pulses and 350 mW in 65 fs pulses, both operating at 92 MHz. The maximum obtained pulse energy reaches 5 nJ. A double-sided pumping scheme with two high power blue diode lasers was used for the output power scaling. The cavity design and the experimental results will be discussed in more details.

  13. Comparing laser induced plasmas formed in diode and excimer pumped alkali lasers.

    Science.gov (United States)

    Markosyan, Aram H

    2018-01-08

    Lasing on the D 1 transition (6 2 P 1/2 → 6 2 S 1/2 ) of cesium can be reached in both diode and excimer pumped alkali lasers. The first uses D 2 transition (6 2 S 1/2 → 6 2 P 3/2 ) for pumping, whereas the second is pumped by photoexcitation of ground state Cs-Ar collisional pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (excimers). Despite lasing on the same D 1 transition, differences in pumping schemes enables chemical pathways and characteristic timescales unique for each system. We investigate unavoidable plasma formation during operation of both systems side by side in Ar/C 2 H 6 /Cs.

  14. Comparing the 810nm diode laser with conventional surgery in orthodontic soft tissue procedures.

    Science.gov (United States)

    Ize-Iyamu, I N; Saheeb, B D; Edetanlen, B E

    2013-09-01

    To compare the use of the 810nm diode laser with conventional surgery in the management of soft tissue mucogingival problems associated with orthodontic treatment. Orthodontic patients requiring different soft tissue surgical procedures were randomly assigned to receive conventional surgery or soft tissue diode laser, (wavelength 810 nm). Parameters documented include the type of anaesthesia used, intra and post operative pain, bleeding, the use of scalpel and sutures. The chi-squared test was used to test for significance at 95% confidence level. Probability values (p-values) less than 0.05 were regarded as significant. Only 2(16.7%) of the procedures carried out with the soft tissue laser required infiltration anaesthesia compared to 10 (90.9%) with conventional surgery and this was significant (Pdiode laser (Pdiode laser. No sutures were used in all soft tissue cases managed with the diode laser and this was significant (Pdiode laser required less infiltration anaesthesia, had reduced bleeding during and after surgery, rapid postoperative haemostasis, elimination of the need for sutures and an improved postoperative comfort and healing.

  15. High power conversion efficiency and wavelength-stabilized narrow bandwidth 975nm diode laser pumps

    Science.gov (United States)

    Kanskar, M.; Cai, J.; Galstad, C.; He, Y.; Macomber, S. H.; Stiers, E.; Tatavarti-Bharatam, S. R.; Botez, D.; Mawst, L. J.

    2006-05-01

    We report on improvement from 50% to 70% power conversion efficiency on a 5-bar stack with 500 W of CW power at 25C coolant temperature resulting from a multi-pronged optimization approach. We also report on wavelength stabilization (0.07 nm/C) and emission bandwidth narrowing (0.3 nm at FWHM) of diode laser pump sources for precision pumping the upper transition levels of lasers that require narrow and stable pump sources such as Er/Yb co-doped or Yb:YAG lasers. These results have been achieved by integration of a Bragg grating inside a semiconductor laser cavity forming a low-loss, weak distributed feedback (DFB) laser, which results in record 53% wall-plug efficiency at 3 W CW operation and 25°C heatsink temperature from a 100-μm aperture diode laser and 45 W of wavelength-locked CW power from a 20% fill factor bar. This technique can be readily applied to diode laser structures for other strategic pump wavelengths.

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

    Directory of Open Access Journals (Sweden)

    Leon Shterengas

    2016-05-01

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

  17. 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

    2010-01-01

    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...

  18. The future of diode pumped solid state lasers and their applicability to the automotive industry

    Science.gov (United States)

    Solarz, R.; Beach, R.; Hackel, L.

    1994-03-01

    The largest commercial application of high power lasers is for cutting and welding. Their ability to increase productivity by introducing processing flexibility and integrated automation into the fabrication process is well demonstrated. This paper addresses the potential importance of recent developments in laser technology to further impact their use within the automotive industry. The laser technology we will concentrate upon is diode laser technology and diode-pumped solid-state laser technology. We will review present device performance and cost and make projections for the future in these areas. Semiconductor laser arrays have matured dramatically over the last several years. They are lasers of unparalleled efficiency (greater than 50%), reliability (greater than 10,000 hours of continuous operation), and offer the potential of dramatic cost reductions (less than a dollar per watt). They can be used directly in many applications or can be used to pump solid-state lasers. When used as solid-state laser pump arrays, they simultaneously improve overall laser efficiency, reduce size, and improve reliability.

  19. Intensity noise properties of Nd:YVO 4 microchip lasers pumped with an amplitude squeezed diode laser

    Science.gov (United States)

    Becher, C.; Boller, K.-J.

    1998-02-01

    We report on intensity noise measurements of single-frequency Nd:YVO 4 microchip lasers optically pumped with amplitude squeezed light from an injection-locked diode laser. Calibrated homodyne measurements show a minimum intensity noise of 10.1 dB above the SQL at a frequency of 100 kHz. The measured intensity noise spectra are described with high accuracy by a theoretical model based on the quantum mechanical Langevin rate equations, including classical and quantum noise sources.

  20. LASER BIOLOGY AND MEDICINE: Application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air

    Science.gov (United States)

    Stepanov, E. V.; Milyaev, Varerii A.

    2002-11-01

    The application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air in biomedical diagnostics is discussed. The principle of operation and the design of a laser analyser for studying the composition of exhaled air are described. The results of detection of gaseous biomarkers in exhaled air, including clinical studies, which demonstrate the diagnostic possibilities of the method, are presented.

  1. Determination of temperature and residual laser energy on film fiber-optic thermal converter for diode laser surgery.

    Science.gov (United States)

    Liu, Weichao; Kong, Yaqun; Shi, Xiafei; Dong, Xiaoxi; Wang, Hong; Zhao, Jizhi; Li, Yingxin

    2017-12-01

    The diode laser was utilized in soft tissue incision of oral surgery based on the photothermic effect. The contradiction between the ablation efficiency and the thermal damage has always been in diode laser surgery, due to low absorption of its radiation in the near infrared region by biological tissues. Fiber-optic thermal converters (FOTCs) were used to improve efficiency for diode laser surgery. The purpose of this study was to determine the photothermic effect by the temperature and residual laser energy on film FOTCs. The film FOTC was made by a distal end of optical fiber impacting on paper. The external surface of the converter is covered by a film contained amorphous carbon. The diode laser with 810 nm worked at the different rated power of 1.0 W, 1.5 W, 2.0 W, 3.0 W, 4.0 W, 5.0 W, 6.0 W, 7.0 W, 8.0 W in continuous wave (CW)and pulse mode. The temperature of the distal end of optical fiber was recorded and the power of the residual laser energy from the film FOTC was measured synchronously. The temperature, residual power and the output power were analyzed by linear or exponential regression model and Pearson correlations analysis. The residual power has good linearity versus output power in CW and pulse modes (R 2  = 0.963, P fiber tip both in CW and pulsed mode while limiting the ability of the laser light to interact directly with target tissue. Film FOTCs can concentrate part of laser energy transferred to heat on distal end of optical fiber, which have the feasibility of improving efficiency and reducing thermal damage of deep tissue.

  2. Light-emitting diode versus laser irradiation phototherapy with lutetium texaphyrin (PCI-0123)

    Science.gov (United States)

    Woodburn, Kathryn W.; Young, Stuart W.; Qing, Fan; Miles, Dale R.; Thiemann, Patricia A.

    1997-05-01

    Lutetium texaphyrin (PCI-0123) is presently in clinical trials for the treatment of neoplasms. An argon-pumped dye laser has mostly been used to generate light for PCI-0123 photoactivation. However, lasers are expensive and produce a limited area of illumination, so the efficacy of light emitting diodes (LEDs) was investigated. An LED array was developed so that the spectral emission matched the far red absorption spectrum of PCI-0123. A preclinical PDT efficacy study comparing the laser and the LED was undertaken using EMT6-bearing animals. The LED and laser light sources were statistically comparable in eradicating the murine mammary sarcomas using PCI-0123 as the photosensitizer.

  3. Three Dimensional Speckle Imaging Employing a Frequency-Locked Tunable Diode Laser

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Bret D.; Bernacki, Bruce E.; Schiffern, John T.; Mendoza, Albert

    2015-09-01

    We describe a high accuracy frequency stepping method for a tunable diode laser to improve a three dimensional (3D) imaging approach based upon interferometric speckle imaging. The approach, modeled after Takeda, exploits tuning an illumination laser in frequency as speckle interferograms of the object (specklegrams) are acquired at each frequency in a Michelson interferometer. The resulting 3D hypercube of specklegrams encode spatial information in the x-y plane of each image with laser tuning arrayed along its z-axis. We present laboratory data of before and after results showing enhanced 3D imaging resulting from precise laser frequency control.

  4. Effect of different diode laser wavelengths on root dentin decontamination infected with Enterococcus faecalis.

    Science.gov (United States)

    Borges, Caroline Cristina; Estrela, Carlos; Lopes, Fabiane Carneiro; Palma-Dibb, Regina Guenka; Pecora, Jesus Djalma; De Araújo Estrela, Cyntia Rodrigues; Sousa-Neto, Manoel Damião de

    2017-11-01

    The objective of this study was to evaluate the antibacterial effect and the ultrastructural alterations of diode laser with different wavelengths (808nm and 970nm) and its association with irrigating solutions (2.5% sodium hypochlorite and 2% chlorhexidine) in root dentin contaminated by a five days biofilm. Thirteen uniradicular teeth were sectioned into 100 dentin intraradicular blocks. Initially, the blocks were immersed for 5min in 17% EDTA and washed with distilled water for 5min, then samples were sterilized for 30min at 120°C. The dentin samples were inoculated with 0.1mL of E. faecalis suspension in 5mL BHI (Brain Heart Infusion) and incubated at 37°C for 5days. After contamination, the specimens were distributed into ten groups (n=10) according to surface treatment: GI - 5mL NaOCl 2.5%, GII - 5mL NaOCl 2.5%+808nm diode (0.1W for 20s), GIII - 5mL NaOCl 2.5%+970nm diode (0.5W for 4s), GIV - 808nm diode (0.1W for 20s), GV - 970nm diode (0.5W for 4s), GVI - CHX 2%, GVII - CHX 2%+808nm diode (0.1W for 20s), GVIII - CHX 2%+970nm diode (0.5W for 4s), GIX - positive control and GX - negative control. Bacterial growth was analyzed by turbidity and optical density of the growth medium by spectrophotometry (nm). Then, the specimens were processed for analysis ultrastructural changes of the dentin surface by SEM. The data was subject to the One-way ANOVA test. GI (77.5±12.1), GII (72.5±12.2), GIII (68.7±8.7), GV (68.3±8.7), GVI (62.0±5.5) and GVII (67.5±3.3) were statistically similar and statistically different from GIV (58.8±25.0), GVIII (59.2±4.0) and control groups (pdiode laser; erosion of the intertubular dentin in blocks submitted to 808nm diode laser irradiation; and an increased erosion of the intertubular dentin when 2.5% NaOCl was associated to the different wavelengths lasers. All the therapeutic protocols were able to reduce the bacterial contingent in dentin blocks, and the association of diode laser and solutions did not significantly improve

  5. Defocused Irradiation Mode of Diode Laser for Conservative Treatment of Oral Hemangioma

    Science.gov (United States)

    Fekrazad, Reza; AM Kalhori, Katayoun; Chiniforush, Nasim

    2013-01-01

    Vascular lesions rise from abnormalities in blood vessels or endothelial proliferation. Capillary hemangiomas are formed by small capillaries surrounded by a layer of endothelial cells in a connective tissue stroma. Various treatments are used for these conditions like excisional surgery, sclerotherapy, and recently laser irradiation. In this case study, we report successful treatment of intraoral capillary hemangioma by gallium/aluminum/arsenide (GaAlAs) laser. A 29 year old woman with a red lesion on the upper side of the right maxillary premolar was referred to private dental office. The Diode laser with wavelength of 810 nm was selected for treatment of the lesion in defocused mode by output power of 4 W in continuous mode. No bleeding was observed during surgery which provided better vision for surgeon and resulted in a minimally invasive procedure. According to results, Diode laser can be considered as a conservative modality in treatment of oral capillary hemangioma, especially in the esthetic zone. PMID:25606323

  6. Defect engineering for 650 nm high-power AlGaInP laser diodes

    International Nuclear Information System (INIS)

    Kim, D.S.; Kim, K.C.; Shin, Y.C.; Kang, D.H.; Kim, B.J.; Kim, Y.M.; Park, Y.; Kim, T.G.

    2006-01-01

    To find the optimal growth and annealing conditions for high-power 650 nm band AlGaInP laser diodes, we carried out defect engineering, in which the distribution and density of deep level defects of the laser structure was analyzed. For this purpose, deep level transient spectroscopy (DLTS) measurements were carried out for each layer of the 650 nm band AlGaInP laser. By layer optimization at growth and annealing conditions, the laser diode was able operate stably and kink-free at high power over 220 mW at 70 deg. C. The characteristic temperatures (T ) were 212 K for 25-60 deg. C and 106 K over 60 deg. C

  7. Tunable terahertz wave generation through a bimodal laser diode and plasmonic photomixer.

    Science.gov (United States)

    Yang, S-H; Watts, R; Li, X; Wang, N; Cojocaru, V; O'Gorman, J; Barry, L P; Jarrahi, M

    2015-11-30

    We demonstrate a compact, robust, and stable terahertz source based on a novel two section digital distributed feedback laser diode and plasmonic photomixer. Terahertz wave generation is achieved through difference frequency generation by pumping the plasmonic photomixer with two output optical beams of the two section digital distributed feedback laser diode. The laser is designed to offer an adjustable terahertz frequency difference between the emitted wavelengths by varying the applied currents to the laser sections. The plasmonic photomixer is comprised of an ultrafast photoconductor with plasmonic contact electrodes integrated with a logarithmic spiral antenna. We demonstrate terahertz wave generation with 0.15-3 THz frequency tunability, 2 MHz linewidth, and less than 5 MHz frequency stability over 1 minute, at useful power levels for practical imaging and sensing applications.

  8. Modeling of a diode-pumped thin-disk cesium vapor laser

    Science.gov (United States)

    An, Guofei; Cai, He; Liu, Xiaoxu; Han, Juhong; Zhang, Wei; Wang, Hongyuan; Wang, You

    2018-03-01

    A diode pumped alkali laser (DPAL) provides a significant potential for construction of high-powered lasers. Until now, a series of models have been established to analyze the kinetic process and most of them are based on the end-pumped alkali laser system in which the vapor cell are usually cylindrical and cuboid. In this paper, a mathematic model is constructed to investigate the kinetic processes of a diode pumped thin-disk cesium vapor laser, in which the cesium vapor and the buffer gases are beforehand filled in a sealed glass cell with a thin-disk structure. We systemically study the influences of the cell temperature and cell thickness on the output features of a thin-disk DPAL. Further, we study the thin-disk DPAL with the W-shaped resonator and multiple-disk configuration. To the best of our knowledge, there have not been any similar reports so far.

  9. Diode-end-pumped single-longitudinal-mode passively Q-switched Nd:GGG laser

    Science.gov (United States)

    Xue, Feng; Zhang, Sasa; Cong, Zhenhua; Huang, Qingjie; Guan, Chen; Wu, Qianwen; Chen, Hui; Bai, Fen; Liu, Zhaojun

    2018-03-01

    Diode-end-pumped passively Q-switched Nd:GGG laser in a ring cavity at 1062 nm was demonstrated. Single-longitudinal-mode laser linewidth less than 0.5 pm was accomplished by unidirectional operation. The maximum output pulse energy was 437 µJ and the pulse width was 43 ns when Cr4+:YAG with an initial transmission of 61% was used.

  10. High speed visible light communication using blue GaN laser diodes

    Science.gov (United States)

    Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

    2016-10-01

    GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

  11. TUNABLE DIODE LASER MEASUREMENTS OF NO2 NEAR 670 NM AND 395 NM. (R823933)

    Science.gov (United States)

    Two single-mode diode lasers were used to record high-resolution absorption spectra of NO2 (dilute in Ar) near 670.2 and 394.5 nm over a range of temperatures (296 to 774 K) and total pressures (2.4 x 10(-2) to 1 atm). A commercial InGaAsP laser was tuned 1.3 cm(-1) at a repetiti...

  12. Repetitive 1 Hz fast-heating fusion driver HAMA pumped by diode pumped solid state laser

    International Nuclear Information System (INIS)

    Mori, Yoshitaka; Sekine, Takashi; Komeda, Osamu

    2014-01-01

    We describe a repetitive fast-heating fusion driver called HAMA pumped by Diode Pumped Solid State Laser (DPSSL) to realize the counter irradiation of sequential implosion and heating laser beams. HAMA was designed to activate DPSSL for inertial confinement fusion (ICF) research and to realize a unified ICF machine for power plants. The details of a four-beam alignment scheme and the results of the counter irradiation of stainless plates are shown. (author)

  13. High gain semiconductor optical amplifier — Laser diode at visible wavelength

    KAUST Repository

    Shen, Chao

    2017-02-07

    We reported on the first experimental demonstration of a two-section semipolar InGaN-based laser diode with monolithically integrated semiconductor optical amplifier (SOA-LD). The onset of amplification effect was measured at 4V SOA bias (VSOA). The SOA-LD shows a large gain of 5.32 dB at Vsoa = 6 V.

  14. Bactericidal effect of a 405-nm diode laser on Porphyromonas gingivalis

    International Nuclear Information System (INIS)

    Kotoku, Y; Kato, J; Akashi, G; Hirai, Y; Ishihara, K

    2009-01-01

    The study was conducted to determine the effect of 405-nm diode laser irradiation on periodontopathic bacteria such as Porphyromonas gingivalis in vitro. A diluted suspension of P. gingivalis was irradiated directly with a 405-nm diode laser under conditions of 100 mW-10 sec, 100 mW-20 sec, 200 mW-5 sec, 200 mW-10 sec, 200 mW-20 sec, 400 mW-5 sec, 400 mW-10 sec, and 400 mW-20 sec. The energy density ranged from 2.0 to 16.0 J/cm 2 . The irradiated bacterial suspension was spread on a blood agar plate and growth of the colonies was examined after an anaerobic culture for 7 days. Bacterial growth was inhibited under all irradiation conditions, but the bactericidal effect of the 405-nm diode laser depended on the energy density. More than 97% of bacterial growth was inhibited with irradiation at an energy density > 4.0 J/cm 2 . The mechanism of the bactericidal effect is photochemical, rather than photothermal. These findings suggest that a 405-nm diode laser has a high bactericidal effect on P. gingivalis

  15. Bactericidal effect of a 405-nm diode laser on Porphyromonas gingivalis

    Science.gov (United States)

    Kotoku, Y.; Kato, J.; Akashi, G.; Hirai, Y.; Ishihara, K.

    2009-05-01

    The study was conducted to determine the effect of 405-nm diode laser irradiation on periodontopathic bacteria such as Porphyromonas gingivalis in vitro. A diluted suspension of P. gingivalis was irradiated directly with a 405-nm diode laser under conditions of 100 mW-10 sec, 100 mW-20 sec, 200 mW-5 sec, 200 mW-10 sec, 200 mW-20 sec, 400 mW-5 sec, 400 mW-10 sec, and 400 mW-20 sec. The energy density ranged from 2.0 to 16.0 J/cm2. The irradiated bacterial suspension was spread on a blood agar plate and growth of the colonies was examined after an anaerobic culture for 7 days. Bacterial growth was inhibited under all irradiation conditions, but the bactericidal effect of the 405-nm diode laser depended on the energy density. More than 97% of bacterial growth was inhibited with irradiation at an energy density > 4.0 J/cm2. The mechanism of the bactericidal effect is photochemical, rather than photothermal. These findings suggest that a 405-nm diode laser has a high bactericidal effect on P. gingivalis.

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

    NARCIS (Netherlands)

    van Voorst, P.D.

    2008-01-01

    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

  17. Is the 810-nm diode laser the best choice in oral soft tissue therapy?

    Science.gov (United States)

    Akbulut, Nihat; Kursun, E. Sebnem; Tumer, M. Kemal; Kamburoglu, Kivanc; Gulsen, Ugur

    2013-01-01

    Objective: To evaluate the safety and efficacy of an 810-nm diode laser for treatment of benign oral soft tissue lesions. Materials and Methods: Treatment with the 810-nm diode laser was applied to a group of eighteen patients with pathological frenulum and epulis fissuratum; five patients with oral lichen planus, oral leukoplakia, and mucous membrane pemphigoid; and four patients with pyogenic granuloma. Results: Although the conventional surgery wound heals in a fairly short time, in the present study, the simple oral soft tissue lesions healed within two weeks, the white and vesiculobullous lesions healed completely within six weeks, and the pyogenic granuloma lesions healed within four weeks. Any complication was treated by using the 810-nm diode laser. Conclusions: Patient acceptance and satisfaction, without compromising health and function, have been found to be of a high degree in this present study. Thus, we can say that the use of the 810-nm diode laser may indeed be the best choice in oral soft tissue surgery. PMID:24883028

  18. Patient perceptions and clinical efficacy of labial frenectomies using diode laser versus conventional techniques.

    Science.gov (United States)

    Uraz, A; Çetiner, F D; Cula, S; Guler, B; Oztoprak, S

    2018-02-23

    The aim of present study was to compare the keratinized gingival tissue measurements, degree of subjective complaints and functional complications of using an 980nm diode laser versus a scalpel for labial frenectomies. Thirty-six patients requiring labial frenectomies, between 14 and 51 years old, were randomly assigned to either scalpel or diode laser treatments. The soft tissue measurements, including the keratinized gingiva width (KGW), attached gingiva width (AGW) and attached gingiva thickness (AGT), were recorded before surgery, immediately after, one week later and one, three and six months after surgery. In addition, the functional complications and the morbidity (level of pain, swelling and redness) were evaluated during the first postoperative week using a visual analog scale (VAS). We determined statistically significant gains in the KGW, AGW and AGT after surgery in both groups; however, there was no significant difference between the study groups. The VAS scores indicated that the patients treated with a diode laser had less discomfort and functional complications compare with scalpel surgery. The results described above show that diode laser surgery offers a safe, impressive alternative for labial frenectomies that are comfortable for the patients. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  19. Assessment of Hydrogen Sulfide Minimum Detection Limits of an Open Path Tunable Diode Laser

    Science.gov (United States)

    During June 2007, U.S. EPA conducted a feasibility study to determine whether the EPA OTM 10 measurement approach, also known as radial plume mapping (RPM), was feasible. A Boreal open-path tunable diode laser (OP-TDL) to collect path-integrated hydrogen sulfide measurements alon...

  20. A New Cost-Effective Diode Laser Polarimeter Apparatus Constructed by Undergraduate Students

    Science.gov (United States)

    Lisboa, Pedro; Sotomayor, Joo; Ribeiro, Paulo

    2010-01-01

    The construction of a diode laser polarimeter apparatus by undergraduate students is described. The construction of the modular apparatus by undergraduate students gives them an insight into how it works and how the measurement of a physical or chemical property is conducted. The students use the polarimeter to obtain rotation angle values for the…

  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

    2013-01-01

    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...

  2. Stable injection locking of diode lasers through a phase-modulated double phase-conjugate mirror

    Science.gov (United States)

    Iida, Kenichi; Tan, Xiaodi; Shimura, Tsutomu; Kuroda, Kazuo

    1997-04-01

    The stable injection locking of 0.8- m diode lasers with a double phase-conjugate mirror (DPCM) was achieved. Phase modulation by piezoelectric transducers allowed us to keep two input beams of the DPCM mutually incoherent during locking. We preserved the high performance of the DPCM and retained stable locking for more than an hour.

  3. Effects of 810-nanometer diode laser as an adjunct to mechanical ...

    African Journals Online (AJOL)

    Effects of 810-nanometer diode laser as an adjunct to mechanical periodontal treatment on clinical periodontal parameters and gingival crevicular fluid ... Plaque index, gingival index (GI), bleeding on probing (BoP), probing depth (PD), clinical attachment level and gingival recession were assessed at baseline and 8 weeks ...

  4. Integrated photonic platform based on semipolar InGaN/GaN multiple section laser diodes

    KAUST Repository

    Shen, Chao

    2017-11-30

    The challenges to realizing III-nitride photonic integrated circuit (PIC) are discussed. Utilizing InGaN-based multi-section laser diode (LD) on semipolar GaN substrate, the seamless on-chip integration of III-nitride waveguide photodetector (WPD) in the visible regime has been demonstrated.

  5. Element selective detection of molecular species applying chromatographic techniques and diode laser atomic absorption spectrometry.

    Science.gov (United States)

    Kunze, K; Zybin, A; Koch, J; Franzke, J; Miclea, M; Niemax, K

    2004-12-01

    Tunable diode laser atomic absorption spectroscopy (DLAAS) combined with separation techniques and atomization in plasmas and flames is presented as a powerful method for analysis of molecular species. The analytical figures of merit of the technique are demonstrated by the measurement of Cr(VI) and Mn compounds, as well as molecular species including halogen atoms, hydrogen, carbon and sulfur.

  6. Diode laser assisted minimal invasive sphenoidotomy for endoscopic transphenoidal pituitary surgery: our technique and results.

    Science.gov (United States)

    Lee, Jih-Chin; Lai, Wen-Sen; Ju, Da-Tong; Chu, Yueng-Hsiang; Yang, Jinn-Moon

    2015-03-01

    During endoscopic sinus surgery (ESS), intra-operative bleeding can significantly compromise visualization of the surgical field. The diode laser that provides good hemostatic and vaporization effects and excellent photocoagulation has been successfully applied in endoscopic surgery with several advantages. The current retrospective study demonstrates the feasibility of diode laser-combined endoscopic sinus surgery on sphenoidotomy. The patients who went through endoscopic transphenoidal pituitary surgery were enrolled. During the operation, the quality of the surgical field was assessed and graded by the operating surgeon using the scale proposed by Boezaart. The mean operation time was 37.80 ± 10.90 minutes. The mean score on the quality of surgical field was 1.95. A positive correlation between the lower surgical field quality score and the shorter surgical time was found with statistical significance (P < 0.0001). No infections, hemorrhages, or other complications occurred intra- or post-operatively. The diode laser-assisted sphenoidotomy is a reliable and safe approach of pituitary gland surgery with minimal invasiveness. It is found that application of diode laser significantly improved quality of surgical field and shortened operation time. © 2015 Wiley Periodicals, Inc.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

  8. Optical response characteristics of strained uniform fiber Bragg grating using laser diode

    Science.gov (United States)

    Setiono, Andi; Widiyatmoko, Bambang; Purnamaningsih, Retno Wigajatri

    2015-01-01

    The working principle of the FBG strain sensor using laser diode (λ = 1551.9 - 1553 nm) as a light source is reported. Experimental results show that by straining the bare uniform FBG (λB = 1552 nm) for every 0.01 mm in room temperature, the transmitted and refelcted power were varied according to the state of FBG strains.

  9. How does external feedback cause AlGaAs-based diode lasers to degrade?

    DEFF Research Database (Denmark)

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

    2013-01-01

    The effect of external feedback on the degradation of 808 nm emitting AlGaAs-based high-power broad-area diode lasers is studied. For this purpose, early stages of gradual degradation are induced by accelerated aging at high power levels. While the quantum well that actually experiences the highest...

  10. Spectral shaping of a 10 W diode laser-Yb-fiber amplifier system

    NARCIS (Netherlands)

    Adhimoolam, B.; Lindsay, I.D.; Lee, Christopher James; Gross, P.; Boller, Klaus J.; Klein, M.E.

    2006-01-01

    We describe a continuous-wave master-oscillator power-amplifier system based on a distributed Bragg reflection diode laser and an Yb doped fiber amplifier. The observed optical spectrum of the amplified seed source can be tailored to arbitrary shapes and widths between 30 MHz and greater than 1 GHz

  11. Diode laser coagulation for the treatment of epistaxis in a Scottish fold cat

    Science.gov (United States)

    Aoki, Takuma; Madarame, Hiroo; Sugimoto, Keisuke; Sunahara, Hiroshi; Fujii, Yoko; Kanai, Eiichi; Ito, Tetsuro

    2015-01-01

    We report the case of a 4-year-old, castrated 4.2-kg Scottish fold cat with recurrent epistaxis that was unresponsive to medical therapy. Diathermocoagulation of the nasal mucosa with a diode laser controlled the epistaxis and there was no significant recurrence of epistaxis during 1 year of follow-up. PMID:26130838

  12. Comparison of Alexandrite and Diode Lasers for Hair Removal in Dark and Medium Skin: Which is Better?

    Science.gov (United States)

    Mustafa, Farhad Hamad; Jaafar, Mohamad Suhimi; Ismail, Asaad Hamid; Mutter, Kussay Nugamesh

    2014-01-01

    To improve laser hair removal (LHR) for dark skin, the fluence rate reaching the hair follicle in LHR is important. This paper presents the results of a comparative study examining the function of wavelength on dark skin types using 755 nm alexandrite and 810 nm diode lasers. The structure of the skin was created using a realistic skin model by the Advanced Systems Analysis Program. In this study, the alexandrite laser (755 nm) and diode laser (810 nm) beam-skin tissue interactions were simulated. The simulation results for both lasers differed. The transmission ratio of the diode laser to the dark skin dermis was approximately 4% more than that of the alexandrite laser for the same skin type. For the diode laser at skin depth z = 0.67 mm, the average transmission ratios of both samples were 36% and 27.5%, but those for the alexandrite laser at the same skin depth were 32% and 25%. Both lasers were suitable in LHR for dark skin types, but the diode laser was better than the alexandrite laser because the former could penetrate deeper into the dermis layer.

  13. Evaluation of Diode laser (940 nm irradiation effect on microleakage in class V composite restoration before and after adhesive application

    Directory of Open Access Journals (Sweden)

    loghman rezaei

    2018-03-01

    Full Text Available Introduction: Nowadays, the main focus of dental studies is on adhesive dental materials; since clinical long-term success of bonded restorations depended more on marginal microleakage minimization. So, the aim of this study was Evaluation of Diode laser irradiation effect on microleakage in class V composite restoration before and after adhesive application. Materials and methods: In this in vitro-experimental study, standard class V cavity was prepared on lingual and buccal surfaces of 60 premolar teeth. For evaluation of microleakage, 60 teeth were divided randomly into four groups A, B, C, D (n=15: A primer + adhesive (Clearfil TM SE Bond, B primer + Diode laser + adhesive (940nm wave-length, 21J total energy, 0.7W power, 30s irradiation time C primer + adhesive + Diode laser D primer + Diode laser + adhesive + Diode laser. Then, restoration was completed by Z250 composite. For data analyzing, we used SPSS 16 software. For statistical analysis, we used Non-parametric Kruskal-Wallis & Mann-Whitney tests at 0.05% significance level.  Results: According to non-parametric Kruskal-Wallis test, microleakage scores had not significant difference before and after laser irradiation on gingival margins (p=0.116. But, in occlusal margins the results were significant among the groups (p=0.015. Also according to non-parametric Mann-Whitney tests among the occlusal microleakage scores, group B and D (Diode laser irradiation after primer and Diode laser irradiation after primer and adhesive showed significant results. Conclusion: This study findings showed that in 6th generation adhesives, Diode laser irradiation on self-etch primer before bonding have significant effect on reduction of occlusal marginal microleakage in class V cavities although there was no significant positive effect of Diode laser on gingival margins.

  14. Effect of Diode Laser on Healing of Tooth Extraction Socket: An Experimental Study in Rabbits.

    Science.gov (United States)

    Hamad, Shehab Ahmed; Naif, Jandar S; Abdullah, Mahdi A

    2016-09-01

    To evaluate the effect of low-level laser therapy on healing of extracted tooth socket of healthy rabbits. The sample of this study was 20 male rabbits of 2-2.5 kg weight with age range of 8-12 months. Right and left lower first premolar teeth were extracted. The extraction sockets of lower right first premolar were irradiated with 0.9 W gallium-aluminum-arsenide (GaAlAs) diode laser for 5 min, immediately after extraction and then every 72 h for the next 12 days. The extraction socket of left side were not exposed to laser and served as a control. The animals were sacrificed after 7, 14, 30 and 45 days and the experimental and control sockets were removed from the harvested mandibles and prepared for haematoxylin and eosin staining and Masson's stain. The prepared slides were examined under light microscope for histological and histomorphometric examination. The histological examination showed that diode laser-treated sockets demonstrated early formed new bone with faster maturation of primary bone to secondary bone as compared to non-treated control sockets. Histomorphometric analysis revealed a statistically significant increase in the density and volume of trabecular bone in laser-treated sockets than control sockets. Diode laser application to tooth extraction socket has a positive effect on bone formation.

  15. Temperature changes accompanying near infrared diode laser endodontic treatment of wet canals.

    Science.gov (United States)

    Hmud, Raghad; Kahler, William A; Walsh, Laurence J

    2010-05-01

    Diode laser endodontic treatments such as disinfection or the generation of cavitations should not cause deleterious thermal changes in radicular dentin. This study assessed thermal changes in the root canal and on the root surface when using 940 and 980 nm lasers at settings of 4 W/10 Hz and 2.5 W/25 Hz, respectively, delivered into 2000-mum fibers to generate cavitations in water. The root surface temperature in the apical third was recorded, as was the water temperature in coronal, middle, and apical third regions, by using thermocouples placed inside the canal. Lasing was undertaken with either rest periods or rinsing between 5-second laser exposures. Both diode lasers induced only modest temperature changes on the external root surface at the settings used. Even though the temperature of the water within the canal increased during lasing by as much as 30 degrees C, the external root surface temperature increased by only a maximum of 4 degrees C. Irrigation between laser exposures was highly effective in minimizing thermal changes within the root canal and on the root surface. Diode laser parameters that induce cavitation do not result in adverse thermal changes in radicular dentin. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  16. Comparison of two diode lasers on bactericidity in root canals--an in vitro study.

    Science.gov (United States)

    Beer, Franziska; Buchmair, Alfred; Wernisch, Johann; Georgopoulos, Apostolos; Moritz, Andreas

    2012-03-01

    This in vitro study compares two 810-nm and 940-nm diode lasers on bacterial kill in root canals of extracted human teeth and shows the clinical relevance of different treatment modalities. Ninety root canals of single-rooted human teeth were prepared up to ISO 70, steam sterilized, and assigned to two test groups (810 nm, 940 nm) and one control group. Following an initiatory experiment in which access opening of root canals and surrounding cavity were excluded from irradiation in the main experiment, 60 teeth were inoculated with 2 μl of either Escherichia coli or Enterococcus faecalis suspension. Laser irradiation was performed, additionally including access opening of root canals and surrounding cavity in the laser treatment. Excluding access opening of root canals and surrounding cavity from the laser treatment, the diode laser achieved an average bacterial reduction of Escherichia coli of 76.06% (810 nm) and 68.15% (940 nm), while including access cavities showed an average bacterial reduction of Escherichia coli of 97.84% (810 nm) and 98.83% (940 nm) and an average bacterial reduction of Enterococcus faecalis of 98.8% (810 nm) and 98.66% (940 nm). Diode laser wavelengths are effective in endodontic therapy. It seems to be clinically relevant that additional irradiation of the access cavity produces significantly better bactericidal results.

  17. Automated assembly of fast-axis collimation (FAC) lenses for diode laser bar modules

    Science.gov (United States)

    Miesner, Jörn; Timmermann, Andre; Meinschien, Jens; Neumann, Bernhard; Wright, Steve; Tekin, Tolga; Schröder, Henning; Westphalen, Thomas; Frischkorn, Felix

    2009-02-01

    Laser diodes and diode laser bars are key components in high power semiconductor lasers and solid state laser systems. During manufacture, the assembly of the fast axis collimation (FAC) lens is a crucial step. The goal of our activities is to design an automated assembly system for high volume production. In this paper the results of an intermediate milestone will be reported: a demonstration system was designed, realized and tested to prove the feasibility of all of the system components and process features. The demonstration system consists of a high precision handling system, metrology for process feedback, a powerful digital image processing system and tooling for glue dispensing, UV curing and laser operation. The system components as well as their interaction with each other were tested in an experimental system in order to glean design knowledge for the fully automated assembly system. The adjustment of the FAC lens is performed by a series of predefined steps monitored by two cameras concurrently imaging the far field and the near field intensity distributions. Feedback from these cameras processed by a powerful and efficient image processing algorithm control a five axis precision motion system to optimize the fast axis collimation of the laser beam. Automated cementing of the FAC to the diode bar completes the process. The presentation will show the system concept, the algorithm of the adjustment as well as experimental results. A critical discussion of the results will close the talk.

  18. Performance and reliability of high power 7xx nm laser diodes

    Science.gov (United States)

    Bao, Ling; Wang, Jun; Devito, Mark; Xu, Dapeng; Grimshaw, Mike; Dong, Weimin; Guan, Xingguo; Huang, Hua; Leisher, Paul; Zhang, Shiguo; Wise, Damian; Martinsen, Robert; Haden, Jim

    2011-02-01

    High power diode lasers in 7xx-nm region, have been needed for various applications. Compared to 9xx nm lasers that have been developed extensively in the last 20 years, high power lasers at 7xx-nm region presents much more challenges for operation power, efficiency, temperature performance and reliability. This paper will present recent progresses on 7xx nm laser diodes for the above attributes. Two laser designs will be reviewed and high power diode laser performance and reliability will be presented. Single emitter devices, with 200μm wide emitting width, show up to 10W reliable operation power, with peak efficiency more than 65%. Accelerated life testing at 12A, 50°C heatsink temperature has been running for thousands of hours. High temperature performance and high COMD threshold (> 20W) will also be shown. Life-test failure modes will also be discussed. In summary, with advanced epitaxial structure design and MOCVD process, critical facet passivation and advanced heatsink and bonding technology, 7xx-8xx nm devices have been demonstrated with high performance and reliability similar to those of 9xx nm devices.

  19. Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

    Science.gov (United States)

    Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

    2015-09-15

    We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

  20. Antibacterial Activity of Diode Laser and Sodium Hypochlorite in Enterococcus Faecalis-Contaminated Root Canals.

    Science.gov (United States)

    Sohrabi, Khosrow; Sooratgar, Aidin; Zolfagharnasab, Kaveh; Kharazifard, Mohammad Javad; Afkhami, Farzaneh

    2016-01-01

    The aim of the present in vitro study was to evaluate the disinfection ability of 980-nm diode laser in comparison with sodium hypochlorite (NaOCl) as a common root canal irrigant in canals infected with Enterococcus faecalis (E. faecalis). The root canals of 18 extracted single-rooted premolars were prepared by rotary system. After decoronation, the roots were autoclaved. One specimen was chosen for the negative control, and the remaining teeth were incubated with E. faecalis suspension for two weeks. Subsequently, one specimen was selected as the positive control and the remaining samples were divided into two groups (n=8). The samples of the first group were irrigated with 5.25% NaOCl and the second group were treated with a 980-nm diode laser. Microbial samples were taken from the root canals and bacterial cultivation was carried out. The average value and the standard deviation of colony-forming units (CFU) of each specimen were measured using descriptive statistics. The student's t-test was used to compare the reduction in CFU in each group. The equality of variance of CFU was measured by the Levene's test. NaOCl resulted in 99.87% removal of the bacteria and showed significantly more antibacterial effect compared to the 980-nm diode laser which led to 96.56% bacterial reduction (P<0.05). Although 5.25% NaOCl seems to reduce E. faecalis more effectively, the diode laser also reduced the bacterial count. Therefore a 980-nm diode laser could be considered as a complementary disinfection method in root canal treatment.

  1. High brightness direct diode laser with kW output power

    Science.gov (United States)

    Fritsche, Haro; Kruschke, Bastian; Koch, Ralf; Ferrario, Fabio; Kern, Holger; Pahl, Ulrich; Pflueger, Silke; Gries, Wolfgang

    2014-03-01

    High power, high brightness diode lasers are beginning to challenge solid state lasers, i.e. disk and fiber lasers. The core technologies for brightness scaling of diode lasers are optical stacking and dense spectral combining (DSC), as well as improvements of the diode material. Diode lasers will have the lowest cost of ownership, highest efficiency and most compact design among all lasers. In our modular product design tens of single emitters are combined in a compact package and launched into a 200 μm fiber with 0.08 NA. Dense spectral combining enables power scaling from 80 W to kilowatts. Volume Bragg Gratings and dichroic filters yield high optical efficiencies of more than 80% at low cost. Each module emits up to 500 W with a beam quality of 5.5 mm*mrad and less than 20 nm linewidth. High speed switching power supplies are integrated into the module and rise times as short as 6 μs have been demonstrated. Fast control algorithms based on FPGA and embedded microcontroller ensure high wall plug efficiency with a unique control loop time of only 30 μs. Individual modules are spectrally combined to result in direct diode laser systems with kilowatts of output power at identical beam quality. For low loss fiber coupling a 200 μm fiber is used and the NA is limited to 0.08 corresponding to a beam quality of 7.5 mm*mrad. The controller architecture is fully scalable without sacrificing loop time. We leverage automated manufacturing for cost effective, high yield production. A precision robotic system handles and aligns the individual fast axis lenses and tracks all quality relevant data. Similar technologies are also deployed for dense spectral combining aligning the VBG and dichroic filters. Operating at wavelengths between 900 nm and 1100 nm, these systems are mainly used in cutting and welding, but the technology can also be adapted to other wavelength ranges, such as 793 nm and 1530 nm. Around 1.5 μm the diodes are already successfully used for resonant

  2. Tm:GGAG crystal for 2μm tunable diode-pumped laser

    Science.gov (United States)

    Šulc, Jan; Boháček, Pavel; Němec, Michal; Fibrich, Martin; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin

    2016-04-01

    The spectroscopy properties and wavelength tunability of diode pumped laser based on Tm-doped mixed gadolinium-gallium-aluminium garnet Gd3(GaxAl1-x)5O12 (Tm:GGAG) single crystal were investigated for the first time. The crystal was grown by Czochralski method in a slightly oxidative atmosphere using an iridium crucible. The tested Tm:GGAG sample was cut from the grown crystal boule perpendicularly to growth direction (c-axis). The composition of sample was determined using electron microprobe X-ray elemental analysis. For spectroscopy and laser experiments 3.5mm thick plane-parallel face-polished plate (without AR coatings) with composition Gd2.76Tm0.0736Ga2.67Al2.50O12 (2.67 at.% Tm/Gd) was used. A fiber (core diameter 400 μm, NA= 0.22) coupled laser diode (emission wavelength 786 nm) was used for longitudinal Tm:GGAG pumping. The laser diode was operating in the pulsed regime (10 ms pulse length, 10 Hz repetition rate, maximum power amplitude 18 W). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.8- 2.10 μm, HT @ 0.78 μm) and curved (r = 150mm) output coupler with a reflectivity of » 97% @ 1.8- 2.10 µm. The maximum laser output power amplitude 1.14W was obtained at wavelength 2003nm for absorbed pump power amplitude 4.12W. The laser slope efficiency was 37% in respect to absorbed pumping power. Wavelength tuning was accomplished by using 2mm thick MgF2 birefringent filter placed inside the laser resonator at the Brewster angle. The laser was continuously tunable over 180nm in a spectral region from 1856nm to 2036 nm.

  3. Effect of diode laser radiation in root canal wall dentine: a microbiological study

    Science.gov (United States)

    Gutknecht, Norbert; Conrads, Georg; Apel, Christian; Schubert, Claus; Lampert, Friedrich

    2000-03-01

    The aim of this study was to investigate the antibacterial effect of a diode laser in deep root canal dentine. The microbial colonization of root canal dentine can lead to failures in conventional endodontic treatment if only an inadequate bacterial reduction is achieved through canal treatment and chemical disinfection. 100 micrometer, 300 micrometer and 500 micrometer bovine dentine slices obtained by longitudinal sections were sterilized and inoculated on one side with an Enterococcus faecalis suspension. Laser radiation was performed on the opposite side with the diode laser, emits light at 810 nm and operates in the continuous wave mode (cw). Radiation was performed using a 400 micrometer tapered fiber tip at an angle of approx. 5 degrees to the surface over a period of 30 s. The output power at the distal end of the tip was 0.6 watt. The bacteria were then eluted through vibration and cultured on blood agar plates. The colony count reflected the antibacterial effect of laser radiation as a function of the layer thickness. A mean bacterial reduction of 74% was achieved even with a 500 micrometer thick slice. This investigation indicates that the diode laser can support the bacterial reduction in endodontic treatment.

  4. Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid-IR Laser Material

    Science.gov (United States)

    2016-09-01

    ARL-TR-7818 ● SEP 2016 US Army Research Laboratory Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid- IR Laser Material by...Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid- IR Laser Material by Larry D Merkle Sensors and Electron Devices Directorate, ARL Stephen...as a Diode-Pumpable Mid- IR Laser Material 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Larry D Merkle

  5. Efficient generation of 3.9 W of diffraction-limited green light with spectrally combined tapered diode lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Andersen, Peter E.

    We propose an efficient concept increasing the power of diode laser systems in the visible spectral range. In comparison with second harmonic generation of single emitters, spectral beam combining with subsequent sum-frequency generation enhances the available power significantly. Combining two...... 1060 nm tapered diode lasers, we achieve a 2.5-3.2 fold increase of green light with a maximum power of 3.9 Watts in a diffraction-limited beam. At this level, diode lasers have a high application potential, for example, within the biomedical field. In order to enhance the power even further, our...

  6. 303 nm continuous wave ultraviolet laser generated by intracavity frequency-doubling of diode-pumped Pr3+:LiYF4 laser

    Science.gov (United States)

    Zhu, Pengfei; Zhang, Chaomin; Zhu, Kun; Ping, Yunxia; Song, Pei; Sun, Xiaohui; Wang, Fuxin; Yao, Yi

    2018-03-01

    We demonstrate an efficient and compact ultraviolet laser at 303 nm generated by intracavity frequency doubling of a continuous wave (CW) laser diode-pumped Pr3+:YLiF4 laser at 607 nm. A cesium lithium borate (CLBO) crystal, cut for critical type I phase matching at room temperature, is used for second-harmonic generation (SHG) of the fundamental laser. By using an InGaN laser diode array emitting at 444.3 nm with a maximum incident power of 10 W, as high as 68 mW of CW output power at 303 nm is achieved. The output power stability in 4 h is better than 2.85%. To the best of our knowledge, this is high efficient UV laser generated by frequency doubling of an InGaN laser diode array pumped Pr3+:YLiF4 laser.

  7. Frequency chirped light at large detuning with an injection-locked diode laser.

    Science.gov (United States)

    Teng, K; Disla, M; Dellatto, J; Limani, A; Kaufman, B; Wright, M J

    2015-04-01

    We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generate a 1 GHz frequency chirp in 5 ns.

  8. Frequency chirped light at large detuning with an injection-locked diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Teng, K.; Disla, M.; Dellatto, J.; Limani, A.; Kaufman, B.; Wright, M. J., E-mail: mwright@adelphi.edu [Physics Department, Adelphi University, 1 South Ave., Garden City, New York 11530 (United States)

    2015-04-15

    We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generate a 1 GHz frequency chirp in 5 ns.

  9. Frequency chirped light at large detuning with an injection-locked diode laser

    International Nuclear Information System (INIS)

    Teng, K.; Disla, M.; Dellatto, J.; Limani, A.; Kaufman, B.; Wright, M. J.

    2015-01-01

    We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generate a 1 GHz frequency chirp in 5 ns

  10. THERMAL LENSING MEASUREMENTS IN THE ANISOTROPIC LASER CRYSTALS UNDER DIODE PUMPING

    Directory of Open Access Journals (Sweden)

    P. A. Loiko

    2012-01-01

    Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.

  11. Robust random number generation using steady-state emission of gain-switched laser diodes

    International Nuclear Information System (INIS)

    Yuan, Z. L.; Lucamarini, M.; Dynes, J. F.; Fröhlich, B.; Plews, A.; Shields, A. J.

    2014-01-01

    We demonstrate robust, high-speed random number generation using interference of the steady-state emission of guaranteed random phases, obtained through gain-switching a semiconductor laser diode. Steady-state emission tolerates large temporal pulse misalignments and therefore significantly improves the interference quality. Using an 8-bit digitizer followed by a finite-impulse-response unbiasing algorithm, we achieve random number generation rates of 8 and 20 Gb/s, for laser repetition rates of 1 and 2.5 GHz, respectively, with a ±20% tolerance in the interferometer differential delay. We also report a generation rate of 80 Gb/s using partially phase-correlated short pulses. In relation to the field of quantum key distribution, our results confirm the gain-switched laser diode as a suitable light source, capable of providing phase-randomized coherent pulses at a clock rate of up to 2.5 GHz.

  12. Simulation of laser-induced rectification in a nano-scale diode

    Science.gov (United States)

    Kidd, Daniel; Xu, Xiaojia; Covington, Cody; Watanabe, Kazuyuki; Varga, Kálmán

    2018-02-01

    Time-dependent density functional theory is utilized to simulate an asymmetrical jellium model, representing a nano-scale vacuum-tube diode comprised of bulk lithium. A sharp tip on one end of the jellium model allows for enhanced field emission upon interaction with an external laser field, leading to a preferential net current direction. This is verified by comparing the rate of electron transfer between the effective anode and cathode tips for both the diode jellium model and a symmetric cylinder jellium shape for various laser phase parameters. This rate of transfer is shown to significantly increase with smaller separation distances. With stronger laser intensities, this rate similarly increases but levels off as local near-field enhancements become negligible.

  13. Assessment of Hematological and Immunological Changes Associated With Diode Laser Turbinoplasty

    International Nuclear Information System (INIS)

    Ibrahim, D.R.

    2013-01-01

    20 patients undergoing laser surgery of the inferior turbinate participated in the present study to compare the pre and post-operative changes of the symptoms and signs of allergic rhinitis, blood picture, IgE, interleukin-4, interleukin-5 and interferon-gamma. After one month of diode laser turbinoplasty, there was improvement in clinical symptoms like nasal obstruction, sneezing and rhinorrhoea. Regarding the blood picture, there was marked relative eosinopenia while the total leucocytic count showed a significant increase. The erythroid series showed almost no changes. The operation was accompanied also with a significant decrease in IgE and interleukin-5, at the same time interleukin-4 and interferon-gamma showed insignificant decrease and increase respectively. These results denoted that diode laser inferior turbinoplasty improves not only the clinical manifestations of allergic rhinitis but it has also an immune effect by modulating T-cell function and tilting the Th 1/Th 2 balance towards Th 1 dominant state.

  14. Diode laser irradiation of rat blood and its effect on hemoglobin and plasma

    International Nuclear Information System (INIS)

    Saad-El-Din, A.A.; El-Ahdaal, M.A.; Omran, M.F.

    2002-01-01

    Blood was exposed to diode laser irradiation of wavelength 830 nm and maximum powe of 31.4 MW, with exposure times 15, 30, 45 and 60 minutes. Hemoglobin IR spectra and X-ray crystallography, plasma Na + , K + , Ca + +. cholesterol concentrations and viscosity were measured. There were changes in hemoglobin amide groups as well as changes in the X-ray in hemoglobin structure. Decreases in both Na concentration and plasma viscosity occurred at 15 and 30 minutes of laser exposure. On increasing time to 45 and 60 minutes, the Na concentration and viscosity were increased. K, Ca and cholesterol concentration were decreased linearly with time. Na / K ratio was increased also with time of exposure. The results have been indicated that the diode laser affect the secondary structure of hemoglobin, membranes structures and plasma

  15. Investigation of high-power diode-end-pumped Tm:YLF laser in slab geometry.

    Science.gov (United States)

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

    2015-03-10

    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.

  16. Design modeling of the 100-J diode-pumped solid-state laser for Project Mercury

    Energy Technology Data Exchange (ETDEWEB)

    Orth, C., LLNL

    1998-02-23

    We present the energy, propagation, and thermal modeling for a diode-pumped solid-state laser called Mercury being designed and built at LLNL using Yb:S-FAP [i.e., Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F crystals] for the gain medium. This laser is intended to produce 100 J pulses at 1 to 10 ns at 10 Hz with an electrical efficiency of {approximately}10%. Our modeling indicates that the laser will be able to meet its performance goals.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...... operating around 1060 nm. The light emitted by the laser has a nearly diffraction limited beam quality and a narrow linewidth of less than 6 pm everywhere in the tuning range....

  18. Characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode-pumped Nd:YAG ceramic laser

    International Nuclear Information System (INIS)

    Kim, Duck-Lae; Kim, Byung-Tai

    2010-01-01

    The characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode Nd:YAG ceramic laser were investigated. The thermal lensing effect was compensated for by using a compensator, which was 25 mm away from the laser rod, with a focal length of 30 mm and an effective clear aperture of 22 mm. Using a compensator, the divergence and the beam propagation factor M 2 of the output beam were 5.5 mrad and 2.4, respectively, under a pump power of 12W. The high-frequency components in the compensated laser beam were removed.

  19. Diode laser to treat small oral vascular malformations: A prospective case series study.

    Science.gov (United States)

    Bacci, Christian; Sacchetto, Luca; Zanette, Gastone; Sivolella, Stefano

    2018-02-01

    The current work examined a consecutive series of patients presenting vascular malformations (VMs) and venous lakes (VLs) of the lip and oral mucosa who were treated with transmucosal diode laser applications and assessed over a 1 year period. Fifty-nine patients (31 males and 28 females) presenting low-flow VMs or VLs of the oral cavity were treated transmucosally using a diode laser (with an 830 nm operating wavelength and 1.6 W output power) with a 320 µm diameter flexible fiber. All the lesions were assessed 7 days, 30 days, and 1 year after the laser treatment, and the lesion reduction percentage was scored on a one to five scale. The patients were also asked to assess their pain perception daily during the 7 days following the treatment using a visual analog scale (VAS). There were no procedure-related intra- or post-operative complications; only modest pain intensity was reported. Thirty days after the treatment, lesion reduction was described as excellent or good in 52 cases; it was fair or poor in 7. Six patients (F:M ratio 2:4) required a second diode laser application. At the 1 year follow-up, volume reduction was complete in 48 out of 59 patients; there were five recurrences (F:M ratio 3:2). No relevant gender-related differences were noted. The use of diode laser application to treat small oral VMs and VLs was associated to shorter operating times and fewer postoperative complications with respect to the scapel surgery approach. More than one session may nevertheless be required if the anomaly is larger than 10 mm. Lasers Surg. Med. 50:111-116, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  20. Compact, diode-pumped, solid-state lasers for next generation defence and security sensors

    Science.gov (United States)

    Silver, M.; Lee, S. T.; Borthwick, A.; McRae, I.; Jackson, D.; Alexander, W.

    2015-06-01

    Low-cost semiconductor laser diode pump sources have made a dramatic impact in sectors such as advanced manufacturing. They are now disrupting other sectors, such as defence and security (D&S), where Thales UK is a manufacturer of sensor systems for application on land, sea, air and man portable. In this talk, we will first give an overview of the market trends and challenges in the D&S sector. Then we will illustrate how low cost pump diodes are enabling new directions in D&S sensors, by describing two diode pumped, solid- state laser products currently under development at Thales UK. The first is a new generation of Laser Target Designators (LTD) that are used to identify targets for the secure guiding of munitions. Current systems are bulky, expensive and require large battery packs to operate. The advent of low cost diode technology, merged with our novel solid-state laser design, has created a designator that will be the smallest, lowest cost, STANAG compatible laser designator on the market. The LTD delivers greater that 50mJ per pulse up to 20Hz, and has compact dimensions of 125×70×55mm. Secondly, we describe an ultra-compact, eye-safe, solid-state laser rangefinder (LRF) with reduced size, weight and power consumption compared to existing products. The LRF measures 100×55×34mm, weighs 200g, and can range to greater than 10km with a single laser shot and at a reprate of 1Hz. This also leverages off advances in laser pump diodes, but also utilises low cost, high reliability, packaging technology commonly found in the telecoms sector. As is common in the D&S sector, the products are designed to work in extreme environments, such as wide temperature range (-40 to +71°C) and high levels of shock and vibration. These disruptive products enable next- generation laser sensors such as rangefinders, target designators and active illuminated imagers.

  1. High-power diode-end-pumped Tm:YLF slab laser delivering 189 W at 1890 nm

    CSIR Research Space (South Africa)

    Koen, W

    2010-09-01

    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...

  2. Unidirectional Transition Waves in Bistable Lattices.

    Science.gov (United States)

    Nadkarni, Neel; Arrieta, Andres F; Chong, Christopher; Kochmann, Dennis M; Daraio, Chiara

    2016-06-17

    We present a model system for strongly nonlinear transition waves generated in a periodic lattice of bistable members connected by magnetic links. The asymmetry of the on-site energy wells created by the bistable members produces a mechanical diode that supports only unidirectional transition wave propagation with constant wave velocity. We theoretically justify the cause of the unidirectionality of the transition wave and confirm these predictions by experiments and simulations. We further identify how the wave velocity and profile are uniquely linked to the double-well energy landscape, which serves as a blueprint for transition wave control.

  3. Transient thermal analysis of semiconductor diode lasers under pulsed operation

    Science.gov (United States)

    Veerabathran, G. K.; Sprengel, S.; Karl, S.; Andrejew, A.; Schmeiduch, H.; Amann, M.-C.

    2017-02-01

    Self-heating in semiconductor lasers is often assumed negligible during pulsed operation, provided the pulses are `short'. However, there is no consensus on the upper limit of pulse width for a given device to avoid-self heating. In this paper, we present an experimental and theoretical analysis of the effect of pulse width on laser characteristics. First, a measurement method is introduced to study thermal transients of edge-emitting lasers during pulsed operation. This method can also be applied to lasers that do not operate in continuous-wave mode. Secondly, an analytical thermal model is presented which is used to fit the experimental data to extract important parameters for thermal analysis. Although commercial numerical tools are available for such transient analyses, this model is more suitable for parameter extraction due to its analytical nature. Thirdly, to validate this approach, it was used to study a GaSb-based inter-band laser and an InP-based quantum cascade laser (QCL). The maximum pulse-width for less than 5% error in the measured threshold currents was determined to be 200 and 25 ns for the GaSb-based laser and QCL, respectively.

  4. Holographic injection-locking of a broad-area laser diode via a photorefractive thin film device

    NARCIS (Netherlands)

    van Voorst, P.D.; de Wit, M.R.; Offerhaus, Herman L.; Tay, S.; Thomas, J.; Peyghambarian, N.; Boller, Klaus J.

    2007-01-01

    We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency

  5. Improvement of the beam quality of a broad-area diode laser using double feedback from two external mirrors

    DEFF Research Database (Denmark)

    Chi, M.; Bøgh, A.-S.; Thestrup, B.

    2004-01-01

    In this letter, a symmetric double-feedback configuration, to improve the beam quality of broad-area diode lasers is demonstrated. With this configuration, a symmetric double-lobed far field can be obtained, and this configuration leads to good beam quality. The beam quality factor M-2 of a diode...

  6. Adjunctive use of the diode laser in non-surgical periodontal therapy: exploring the controversy.

    Science.gov (United States)

    Porteous, Mary Sornborger; Rowe, Dorothy J

    2014-04-01

    Despite the controversy regarding clinical efficacy, dental hygienists use the diode laser as an adjunct to non-surgical periodontal therapy. The technique to maximize successful laser therapy outcome is controversial as well. The purpose of this review is to explore the scientific foundation of the controversy surrounding the use of the diode laser as an adjunct to non-surgical periodontal therapy. Further, this paper addresses the weaknesses in study design, the heterogeneity of methodology in the published clinical studies, especially the laser parameters, and how these issues impact the collective clinical and microbial data, and thus conclusions regarding clinical efficacy. Evaluation of the literature identifies possible mechanisms that could contribute to the varied, often conflicting results among laser studies that are the foundation of the controversy surrounding clinical efficacy. These mechanisms include current paradigms of periodontal biofilm behavior, tissue response to laser therapy being dependent on tissue type and health, and that the successful therapeutic treatment window is specific to the target tissue, biofilm composition, laser wavelength, and laser energy delivered. Lastly, this paper discusses laser parameters used in the various clinical studies, and how their diversity contributes to the controversy. Although this review does not establish clinical efficacy, it does reveal the scientific foundation of the controversy and the need for standardized, well designed randomized controlled clinical trials to develop specific guidelines for using the laser as an adjunct to non-surgical periodontal therapy. Using evidence-based laser guidelines would allow dental hygienists to provide more effective non-surgical periodontal care.

  7. 970-nm ridge waveguide diode laser bars for high power DWBC systems

    Science.gov (United States)

    Wilkens, Martin; Erbert, Götz; Wenzel, Hans; Knigge, Andrea; Crump, Paul; Maaßdorf, Andre; Fricke, Jörg; Ressel, Peter; Strohmaier, Stephan; Schmidt, Berthold; Tränkle, Günther

    2018-02-01

    de lasers are key components in material processing laser systems. While mostly used as pump sources for solid state or fiber lasers, direct diode laser systems using dense wavelength multiplexing have come on the market in recent years. These systems are realized with broad area lasers typically, resulting in beam quality inferior to disk or fiber lasers. We will present recent results of highly efficient ridge waveguide (RW) lasers, developed for dense-wavelength-beamcombining (DWBC) laser systems expecting beam qualities comparable to solid state laser systems and higher power conversion efficiencies (PCE). The newly developed RW lasers are based on vertical structures with an extreme double asymmetric large optical cavity. Besides a low vertical divergence these structures are suitable for RW-lasers with (10 μm) broad ridges, emitting in a single mode with a good beam quality. The large stripe width enables a lateral divergence below 10° (95 % power content) and a high PCE by a comparably low series resistance. We present results of single emitters and small test arrays under different external feedback conditions. Single emitters can be tuned from 950 nm to 975 nm and reach 1 W optical power with more than 55 % PCE and a beam quality of M2 < 2 over the full wavelength range. The spectral width is below 30 pm FWHM. 5 emitter arrays were stabilized using the same setup. Up to now we reached 3 W optical power, limited by power supply, with 5 narrow spectral lines.

  8. Development of a low-cost multiple diode PIV laser for high-speed flow visualization

    Science.gov (United States)

    Bhakta, Raj; Hargather, Michael

    2017-11-01

    Particle imaging velocimetry (PIV) is an optical visualization technique that typically incorporates a single high-powered laser to illuminate seeded particles in a fluid flow. Standard PIV lasers are extremely costly and have low frequencies that severely limit its capability in high speed, time-resolved imaging. The development of a multiple diode laser system consisting of continuous lasers allows for flexible high-speed imaging with a wider range of test parameters. The developed laser system was fabricated with off-the-shelf parts for approximately 500. A series of experimental tests were conducted to compare the laser apparatus to a standard Nd:YAG double-pulsed PIV laser. Steady and unsteady flows were processed to compare the two systems and validate the accuracy of the multiple laser design. PIV results indicate good correlation between the two laser systems and verifies the construction of a precise laser instrument. The key technical obstacle to this approach was laser calibration and positioning which will be discussed. HDTRA1-14-1-0070.

  9. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (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.

  10. Comparative study of diode laser versus neodymium-yttrium aluminum: garnet laser versus intense pulsed light for the treatment of hirsutism

    Directory of Open Access Journals (Sweden)

    Neerja Puri

    2015-01-01

    Full Text Available Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG laser and intense pulsed light (IPL on 30 female patients of hirsutism. Materials and Methods: Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. Results: It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40% in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64% in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92% in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. Conclusions: To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

  11. Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

    Directory of Open Access Journals (Sweden)

    Trišić Dijana

    2017-07-01

    Full Text Available Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm, at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

  12. Low-cost 420nm blue laser diode for tissue cutting and hemostasis

    Science.gov (United States)

    Linden, Kurt J.

    2016-03-01

    This paper describes the use of a 420 nm blue laser diode for possible surgery and hemostasis. The optical absorption of blood-containing tissue is strongly determined by the absorption characteristics of blood. Blood is primarily comprised of plasma (yellowish extracellular fluid that is approximately 95% water by volume) and formed elements: red blood cells (RBCs), white blood cells (WBCs) and platelets. The RBCs (hemoglobin) are the most numerous, and due to the spectral absorption characteristics of hemoglobin, the optical absorption of blood has a strong relative maximum value in the 420 nm blue region of the optical spectrum. Small, low-cost laser diodes emitting at 420 nm with tens of watts of continuous wave (CW) optical power are becoming commercially available. Experiments on the use of such laser diodes for tissue cutting with simultaneous hemostasis were carried out and are here described. It was found that 1 mm deep x 1 mm wide cuts can be achieved in red meat at a focused laser power level of 3 W moving at a velocity of ~ 1 mm/s. The peripheral necrosis and thermal damage zone extended over a width of approximately 0.5 mm adjacent to the cuts. Preliminary hemostasis experiments were carried out with fresh equine blood in Tygon tubing, where it was demonstrated that cauterization can occur in regions of intentional partial tubing puncture.

  13. Hair structures are effectively altered during 810 nm diode laser hair epilation at low fluences.

    Science.gov (United States)

    Trelles, Mario A; Urdiales, Fernándo; Al-Zarouni, Marwan

    2010-03-01

    Diode lasers with high fluence and cooling technology are effective at removing unwanted hair but are also associated with discomfort and morbidity, especially when treating dark or tanned skins. Thirty patients with skin phototypes IV and V (range: 23-62 years of age; average: 39 years) underwent a single hair removal treatment using a new diode laser (810 nm) technology that incorporates low fluence but very high average power. The treatment technique employed multiple, in-motion, repetitive laser passes on a 100 cm(2) area of the skin. A 5mm punch biopsy was carried out before and after a single treatment. Tissue samples were harvested and stained with haematoxylin-eosin. The physical integrity of hair follicles was altered with inflammatory infiltrate, hair shaft detachment from its sheath, and perifollicular oedema, related to incipient necrosis. Low fluence but high average power diode laser technology yields significant changes in hair structure and architecture in patients with dark skin types. The procedure caused low levels of discomfort and was well tolerated.

  14. Diode laser surgery. Ab interno and ab externo versus conventional surgery in rabbits.

    Science.gov (United States)

    Karp, C L; Higginbotham, E J; Edward, D P; Musch, D C

    1993-10-01

    Fibroblastic proliferation of subconjunctival tissues remains a primary mechanism of failure in filtration surgery. Minimizing the surgical manipulation of episcleral tissues may reduce scarring. Laser sclerostomy surgery involves minimal tissue dissection, and is gaining attention as a method of potentially improving filter duration in high-risk cases. Twenty-five New Zealand rabbits underwent filtration surgery in one eye, and the fellow eye remained as the unoperated control. Ten rabbits underwent ab externo diode laser sclerostomy surgery, ten underwent ab interno diode sclerostomy surgery, and five had posterior sclerostomy procedures. Filtration failure was defined as a less-than-4-mmHg intraocular pressure (IOP) difference between the operative and control eyes. The mean time to failure for the ab externo, ab interno, and conventional posterior sclerostomy techniques measured 17.4 +/- 11.5, 13.1 +/- 6.7, and 6.0 +/- 3.1 days, respectively. In a comparison of the laser-treated groups with the conventional procedure, the time to failure was significantly longer (P = 0.02) for the ab externo filter. The mean ab interno sclerostomy duration was longer than the posterior lip procedure, but this difference was not statistically significant (P = 0.15). The overall level of IOP reduction was similar in the three groups. These data suggest that diode laser sclerostomy is a feasible technique in rabbits, and the ab externo approach resulted in longer filter duration than the conventional posterior lip procedure in this model.

  15. Compact laser radar based on a subnanosecond laser diode transmitter and a two-dimensional CMOS single-photon receiver

    Science.gov (United States)

    Huikari, Jaakko; Jahromi, Sahba; Jansson, Jussi-Pekka; Kostamovaara, Juha

    2018-02-01

    A pulsed TOF laser radar utilizing the single-photon detection mode has been implemented, and its performance is characterized. The transmitter employs a QW double-heterostructure laser diode producing 0.6 nJ/100 ps laser pulses at a central wavelength of ˜810 nm. The detector is a single-chip IC manufactured in the standard 0.35-μm HV CMOS process, including a 9×9 single-photon avalanche diode (SPAD) array and a 10-channel time-to-digital converter (TDC) circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection to occur only within a predefined time window. The SPAD array also supports a 3×3 SPADs subarray selection feature to respond to the laser spot wandering effect due to the paraxial optics and to reduce background radiation-induced detections. The characterization results demonstrate a distance measurement accuracy of +/-0.5 mm to a target at 34 m having 11% reflectivity. The signal detection rate is 28% at a laser pulsing rate of 100 kHz. The single-shot precision of the laser radar is ˜20 mm (FWHM). The deteriorating impact of high-level background radiation conditions on the SNR is demonstrated, as also is a scheme to improve this by means of detector time gating.

  16. In vitro study of the diode laser effect on artificial demineralized surface of human dental enamel

    International Nuclear Information System (INIS)

    Ebel, Patricia

    2003-01-01

    In scientific literature there are many reports about fusion and resolidification of dental enamel after laser irradiation and their capability to generate surfaces with increased resistance to demineralization compared to non-irradiated areas. The use of high power diode laser on demineralized surfaces of human dental enamel is presented as a good alternative in caries prevention. The purpose of this study is to investigate the morphological changes produced by the use of one high power diode laser on human dental enamel surface after demineralization treatment with lactic acid, under chosen parameters. Fifteen samples of human dental molars were used and divided in four groups: control - demineralization treatment with lactic acid and no irradiation, and demineralization treatment with lactic acid followed of irradiation with 212,20 mJ/cm 2 , 282,84 mJ/cm 2 and 325,38 mJ/cm 2 , respectively. The samples were irradiated with high power diode laser (808 nm) with a 300 μm diameter fiber optics. Black ink was used on enamel surface to enhance the superficial absorption. The samples were studied by optical microscopy and scanning electron microscopy. Modifications on the enamel surfaces were observed. Such modifications were characterized by melted and re-solidified region of the enamel. According with our results the best parameter was 2.0 W, presenting the most uniform surface. The use of high power diode laser as demonstrated in this study is able to promote melting and re-solidification on human dental enamel. (author)

  17. Compact 2050 nm Semiconductor Diode Laser Master Oscillator, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I effort seeks to develop DFB laser master oscillators at the novel wavelength of 12050 nm. Two prototypes will be built, tested, and delivered ....

  18. Diode Laser Surface Alloying of Armor Steel with Tungsten Carbide

    OpenAIRE

    Janicki D.; Górka J.; Kwaśny W.; Gołombek K.; Kondracki M.; Żuk M.

    2017-01-01

    Metal matrix composite (MMC) surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction.

  19. Spectral properties of a broad-area diode laser with off-axis external-cavity feedback

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2013-01-01

    . The intensity noise spectrum of the diode laser shows that the intensity noise is increased strongly by the external-cavity feedback. External-cavity modes are excited in the external cavity even in the off-axis configuration. The peak spacing of the intensity noise spectrum shows that single roundtrip external......Spectral properties, both the optical spectrum and the intensity noise spectrum, of a broad-area diode laser with off-axis external-cavity feedback are presented. We show that the optical spectrum of the diode laser system is shifted to longer wavelengths due to the external-cavity feedback......-cavity modes are excited. We believe that the four-wave mixing process in the broad-area diode laser is responsible for the establishment of the external-cavity mode....

  20. THE DETERMINATION OF A CRITICAL VALUE FOR DYNAMIC STABILITY OF SEMICONDUCTOR LASER DIODE WITH EXTERNAL OPTICAL FEEDBACK

    Directory of Open Access Journals (Sweden)

    Remzi YILDIRIM

    1998-01-01

    Full Text Available In this study, dynamic stability analysis of semiconductor laser diodes with external optical feedback has been realized. In the analysis the frequency response of the transfer function of laser diode H jw( , the transfer m function of laser diode with external optical feedback TF jw( , and optical feedback transfer function m K jw( obtained from small signal equations has been m accomplished using Nyquist stability analysis in complex domain. The effect of optical feedback on the stability of the system has been introduced and to bring the laser diode to stable condition the working critical boundary range of dampig frequency and reflection power constant (R has been determined. In the study the reflection power has been taken as ( .

  1. High Performance self-injection locked 524 nm green laser diode for high bitrate visible light communications

    KAUST Repository

    Shamim, Md. Hosne Mobarok

    2018-03-05

    First demonstration of self-injection locking on 524 nm visible laser diode is presented. Enhancement by ~440 MHz (~30%) in modulation bandwidth, ~7 times reduction in lasing linewidth, and ~10 dB improvement in SMSR is achieved.

  2. Continuous Water Vapor Mass Flux and Temperature Measurements in a Model Scramjet Combustor Using a Diode Laser Sensor

    National Research Council Canada - National Science Library

    Upschulte, B. L; Miller, M. F; Allen, M. G; Jackson, K; Gruber, M; Mathur, T

    1998-01-01

    A sensor for simultaneous measurements of water vapor density, temperature and velocity has been developed based on absorption techniques using room temperature diode lasers (InGaAsP) operating at 1.31 micrometers...

  3. Diode Laser Sensor for Gas Temperature and H2O Concentration in a Scramjet Combustor Using Wavelength Modulation Spectroscopy (Postprint)

    National Research Council Canada - National Science Library

    Rieker, Gregory B; Li, Jonathan T; Jeffries, Jay B; Mathur, Tarun; Gruber, Mark R; Carter, Campbell D

    2005-01-01

    A diode laser absorption sensor which probes three spectral features of water vapor in the near infrared region to infer gas temperature and water vapor concentration near the exit of a scramjet combustor is presented...

  4. Precision atomic beam density characterization by diode laser absorption spectroscopy

    International Nuclear Information System (INIS)

    Oxley, Paul; Wihbey, Joseph

    2016-01-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  5. Precision atomic beam density characterization by diode laser absorption spectroscopy.

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  6. Near-diffraction-limited segmented broad area diode laser based on off-axis spectral beam combining

    DEFF Research Database (Denmark)

    Jensen, O.B.; Thestrup Nielsen, Birgitte; Andersen, Peter E.

    2006-01-01

    The beam quality of a 500-mu m-wide broad area diode laser with five active segments has been improved beyond the beam quality of the individual segments. The principle of this new laser system is based on off-axis feedback in combination with spectral beam combining. By using a double......-feedback scheme we are able to improve the beam quality of the laser by a factor of 23 from M-2 = 55 for the free-running diode laser to M-2 = 2.4 for the laser with feedback at a drive current of 2.2 A. The improved M-2 value is a factor of 3.4 below M-2 = 8.2 for a single free-running segment. This is the first...... time that the beam quality of a segmented broad area diode laser has been improved beyond the beam quality of the individual segments....

  7. Line-shape study of water vapour by tunable diode laser spectrometer in the 822 832 nm wavelength region

    Science.gov (United States)

    Ray, A.; Bandyopadhyay, A.; Ray, B.; Biswas, D.; Ghosh, P. N.

    2004-11-01

    A near-infrared tunable diode laser absorption spectrometer is set up to measure the air-induced broadening coefficients and the line-strength parameters of water-vapour overtone transitions within the (2,1,1)←(0,0,0) band in the 822 832 nm wavelength region. A Hitachi HL8311 E double hetero-junction structure diode laser is used as a probe. The diode laser controller is home-built and stable within ±10 μA and ±10 mK, respectively. The laser-head mount has a simple design and provides easy access whenever changing of the laser head is required. The diode laser emission wavelength is thermally tuned between 50 °C and 12 °C. Thermal tuning of the diode laser emission wavelength is used to reveal the mode structure of the diode laser and to probe the overtone-band transitions of water vapour within its operating wavelength range. Current tuning of the diode laser is used at a fixed laser temperature to study the transitions one at a time. A balanced detector is used to improve the S/N ratio of the spectrum. A phase sensitive detection technique is followed to obtain the first-derivative spectra of the overtone transitions. The first-derivative spectra have been recorded at different air pressures inside the sample cell while the water-vapour pressure is kept fixed. The first-derivative spectrum is numerically integrated to obtain the original line shape. The original line shape is fitted with a Voigt profile by using a nonlinear least-squares fit program to extract the air-broadening coefficient and the line-strength parameter. The data obtained in our work is compared with the results of the HITRAN database.

  8. Wound treatment on a diabetic rat model by a 808 nm diode laser

    International Nuclear Information System (INIS)

    Lau, Pik Suan; Bidin, Noriah; Krishnan, Ganesan; AnaybBaleg, Sana Mohammed; Baktiar, Harzi; Marsin, Faridah M; Sum, Mohamad Bin Md; Nassir, Zaleha; Chong, Pek Lian; Hamid, Asmah

    2015-01-01

    This paper presents a study on the effect of laser irradiation on wound healing. 808 nm diode laser was employed to facilitate the healing of impaired wounds in experimental diabetes using a rat model. Diabetes was induced in male rats by a streptozotocin injection with a dose of 60 mg kg −1 . The disease was verified via measurement of the blood glucose level, which was set having 20 mmol L −1 stability. The rats were randomly distributed into two groups; one served as a control group and the other group was treated with the laser. The power density of the laser used was 0.5 W cm −2 and the wounds were treated for 8 d with the contact time of one second daily. The energy density used was 0.5 J cm −2 . The healing progress was recorded via a digital camera. The recorded images were then transferred into Inspector Matrox and image J programs for the accurate measurement of the healing area. The tissue details of the wound were studied through histology. The wound contraction rate of laser therapy group was found to be two times faster than control group. This indicates that the 808 nm diode laser can accelerate the wound healing process. (paper)

  9. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    Science.gov (United States)

    Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

    2015-10-01

    Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

  10. Selective removal of dental caries with a diode-pumped Er:YAG laser

    Science.gov (United States)

    Yan, Ruth; Chan, Kenneth H.; Tom, Henry; Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel

    2015-02-01

    Selective removal of caries lesions with high precision is best accomplished using lasers operating at high pulse repetition rates utilizing small spot sizes. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to measure the ablation rate and selectivity of sound and demineralized enamel and dentin for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 20-30-μs and evaluate it's potential for the selective removal of natural occlusal lesions on extracted teeth. Microradiography was used to determine the mineral content of the demineralized enamel and dentin of 300-μm thick sections with natural caries lesions prior to laser ablation. The ablation rate was calculated for varying mineral content. In addition, near-IR reflectance measurements at 1500-1700- nm were used to guide the laser for the selective ablation of natural occlusal caries lesions on extracted teeth.

  11. Diode laser-based standoff absorption measurement of water film thickness in retro-reflection

    Science.gov (United States)

    Pan, R.; Brocksieper, C.; Jeffries, J. B.; Dreier, T.; Schulz, C.

    2016-09-01

    A dual-wavelength diode laser-based absorption sensor for standoff point measurements of water film thickness on an opaque surface is presented. The sensor consists of a diode laser source, a foil as backscattering target, and off-axis paraboloids for collecting the fraction of the laser radiation transmitted through the liquid layer via retro-reflection. Laser wavelengths in the near infrared at 1412 and 1353 nm are used where the temperature dependence of the liquid water absorption cross section is known. The lasers are fiber coupled and the detection of the retro-reflected light was accomplished through a multimode fiber and a single photodiode using time-division multiplexing. The water film thickness at a given temperature was determined from measured transmittance ratios at the two laser wavelengths. The sensor concept was first validated with measurement using a temperature-controlled calibration cell providing liquid layers of variable and known thickness between 100 and 1000 µm. Subsequently, the sensor was demonstrated successfully during recording the time-varying thickness of evaporating water films at fixed temperatures. The film thickness was recorded as a function of time at three temperatures down to 50 µm.

  12. Building block diode laser concept for high brightness laser output in the kW range and its applications

    Science.gov (United States)

    Ferrario, Fabio; Fritsche, Haro; Grohe, Andreas; Hagen, Thomas; Kern, Holger; Koch, Ralf; Kruschke, Bastian; Reich, Axel; Sanftleben, Dennis; Steger, Ronny; Wallendorf, Till; Gries, Wolfgang

    2016-03-01

    The modular concept of DirectPhotonics laser systems is a big advantage regarding its manufacturability, serviceability as well as reproducibility. By sticking to identical base components an economic production allows to serve as many applications as possible while keeping the product variations minimal. The modular laser design is based on single emitters and various combining technics. In a first step we accept a reduction of the very high brightness of the single emitters by vertical stacking several diodes in fast axis. This can be theoretically done until the combined fast axis beam quality is on a comparable level as the individual diodes slow axis beam quality without loosing overall beam performance after fiber coupling. Those stacked individual emitters can be wavelength stabilized by an external resonator, providing the very same feedback to each of those laser diodes which leads to an output power of about 100 W with BPP of electronic concept allows addressing further applications, as due to short lead lengths it is capable of generating very short μs pulses up to cw mode operation by simple software commands.

  13. Micro-integrated extended cavity diode lasers for precision potassium spectroscopy in space.

    Science.gov (United States)

    Luvsandamdin, Erdenetsetseg; Kürbis, Christian; Schiemangk, Max; Sahm, Alexander; Wicht, Andreas; Peters, Achim; Erbert, Götz; Tränkle, Günther

    2014-04-07

    We present a micro-integrated, extended cavity diode laser module for space-based experiments on potassium Bose-Einstein condensates and atom interferometry. The module emits at the wavelength of the potassium D2-line at 766.7 nm and provides 27.5 GHz of continuous tunability. It features sub-100 kHz short term (100 μs) emission linewidth. To qualify the extended cavity diode laser module for quantum optics experiments in space, vibration tests (8.1 g(RMS) and 21.4 g(RMS)) and mechanical shock tests (1500 g) were carried out. No degradation of the electro-optical performance was observed.

  14. High passive-stability diode-laser design for use in atomic-physics experiments

    Science.gov (United States)

    Cook, Eryn C.; Martin, Paul J.; Brown-Heft, Tobias L.; Garman, Jeffrey C.; Steck, Daniel A.

    2012-04-01

    We present the design and performance characterization of an external-cavity diode-laser system optimized for high stability, low passive spectral linewidth, low cost, and ease of in-house assembly. The main cavity body is machined from a single aluminum block for robustness to temperature changes and mechanical vibrations, and features a stiff and light diffraction-grating arm to suppress low-frequency mechanical resonances. The cavity is vacuum sealed, and a custom-molded silicone external housing further isolates the system from acoustic noise and temperature fluctuations. Beam shaping, optical isolation, and fiber coupling are integrated, and the design is easily adapted to many commonly used wavelengths. Resonance data, passive-linewidth data, and passive stability characterization of the new design demonstrate that its performance exceeds published specifications for commercial precision diode-laser systems. The design is fully documented and freely available.

  15. 980 nm high brightness external cavity broad area diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2009-01-01

    We demonstrate of-axis spectral beam combining applied to a 980 nm high power broad area diode laser bar. The experiments yielded 9 W of optical power at 30 A of operating current and the measured M2 values of the combined beam from 12 emitters were 1.9 and 6.4 for the fast and the slow axis......, respectively. The slow axis beam quality was 5-6 times better than the value obtained from a single emitter in free running mode. A high brightness of 79 MW/cm2-str was achieved using this configuration. To our knowledge, this is the highest brightness level ever achieved from a broad area diode laser bar....

  16. High power cascade diode lasers emitting near 2 μm

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-28

    High-power two-stage cascade GaSb-based type-I quantum well diode lasers emitting near 2 μm were designed and fabricated. Coated devices with cavity length of 3 mm generated about 2 W of continuous wave power from 100-μm-wide aperture at the current of 6 A. The power conversion efficiency peaked at 20%. Carrier recycling between quantum well gain stages was realized using band-to-band tunneling in GaSb/AlSb/InAs heterostructure complemented with optimized electron and hole injector regions. Design optimization eliminated parasitic optical absorption and thermionic emission, and included modification of the InAs quantum wells of electron and composition and doping profile of hole injectors. Utilization of the cascade pumping scheme yielded 2 μm lasers with improved output power and efficiency compared to existing state-of-the-art diodes.

  17. Laser diode side-pumped Nd:YVO4microchip laser with film-etched microcavity mirrors.

    Science.gov (United States)

    Li, Jiyang; Niu, Yanxiong; Chen, Sanbin; Tan, Yidong

    2017-10-01

    Microchip lasers are applied as the light sources on various occasions with the end-pumping scheme. However, the vibration, the temperature drift, or the mechanical deformation of the pumping light in laser diodes in the end-pumping scheme will lead to instability in the microchip laser output, which causes errors and malfunctioning in the optic systems. In this paper, the side-pumping scheme is applied for improving the disturbance-resisting ability of the microchip laser. The transverse mode and the frequency purity of the laser output are tested. To ensure unicity in the frequency of the laser output, numerical simulations based on Fresnel-Kirchhoff diffraction theory are conducted on the parameters of the microchip laser cavity. Film-etching technique is applied to restrain the area of the film and form the microcavity mirrors. The laser output with microcavity mirrors is ensured to be in single frequency and with good beam quality, which is significant in the applications of microchip lasers as the light sources in optical systems.

  18. Diode-pumped, single frequency Nd:YLF laser for 60-beam OMEGA laser pulse-shaping system

    International Nuclear Information System (INIS)

    Okishev, A.V.; Seka, W.

    1997-01-01

    The operational conditions of the OMEGA pulse-shaping system require an extremely reliable and low-maintenance master oscillator. The authors have developed a diode-pumped, single-frequency, pulsed Nd:YLF laser for this application. The laser generates Q-switched pulses of ∼160-ns duration and ∼10-microJ energy content at the 1,053-nm wavelength with low amplitude fluctuations (<0.6% rms) and low temporal jitter (<7 ns rms). Amplitude and frequency feedback stabilization systems have been used for high long-term amplitude and frequency stability

  19. Hole transport in c-plane InGaN-based green laser diodes

    International Nuclear Information System (INIS)

    Cheng, Yang; Liu, Jianping; Tian, Aiqin; Zhang, Feng; Feng, Meixin; Hu, Weiwei; Zhang, Shuming; Ikeda, Masao; Li, Deyao; Zhang, Liqun; Yang, Hui

    2016-01-01

    Hole transport in c-plane InGaN-based green laser diodes (LDs) has been investigated by both simulations and experiments. It is found that holes can overflow from the green double quantum wells (DQWs) at high current density, which reduces carrier injection efficiency of c-plane InGaN-based green LDs. A heavily silicon-doped layer right below the green DQWs can effectively suppress hole overflow from the green DQWs.

  20. Hole transport in c-plane InGaN-based green laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yang; Liu, Jianping, E-mail: jpliu2010@sinano.ac.cn; Tian, Aiqin; Zhang, Feng; Feng, Meixin; Hu, Weiwei; Zhang, Shuming; Ikeda, Masao; Li, Deyao; Zhang, Liqun; Yang, Hui [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); School of Nano Technology and Nano Bionics, University of Science and Technology of China, Suzhou 215123 (China)

    2016-08-29

    Hole transport in c-plane InGaN-based green laser diodes (LDs) has been investigated by both simulations and experiments. It is found that holes can overflow from the green double quantum wells (DQWs) at high current density, which reduces carrier injection efficiency of c-plane InGaN-based green LDs. A heavily silicon-doped layer right below the green DQWs can effectively suppress hole overflow from the green DQWs.

  1. Micromirror Array Control of a Phase-Locked Laser Diode Array

    Science.gov (United States)

    1995-12-01

    mirror. These mirrors were invented by Larry Hornbeck of Texas Instruments approximately 15 years ago. Two dimensional arrays of micromirrors are...AFIT/GAP/ENP/95D-2 MICROMIRROR ARRAY CONTROL OF A PHASE-LOCKED LASER DIODE ARRAY THESIS Carl J. Christensen, Captain, USAF AFIT/GAP/ENP/95D-2...Approved for public release; distribution unlimited. /99 (;/ Ig M 5 -5 DTiC QUALITY IITSYEGTED AFIT/GAP/ENP/95D-2 MICROMIRROR ARRAY CONTROL OF A PHASE-LOCKED

  2. Time-resolved tunable diode laser absorption spectroscopy of pulsed plasma

    Czech Academy of Sciences Publication Activity Database

    Adámek, Petr; Olejníček, Jiří; Čada, Martin; Kment, Š.; Hubička, Zdeněk

    2013-01-01

    Roč. 38, č. 14 (2013), s. 2428-2430 ISSN 0146-9592 R&D Projects: GA MŠk LH12045; GA ČR(CZ) GAP205/11/0386; GA MŠk LD12002; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : diode lasers * plasma diagnostics * absorption spectroscopy * time resolved Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.179, year: 2013

  3. Stable injection locking of diode lasers through a phase-modulated double phase-conjugate mirror

    Energy Technology Data Exchange (ETDEWEB)

    Iida, K.; Tan, X.; Shimura, T.; Kuroda, K. [Institute of Industrial Science, University of Tokyo, 7-22-1 Roppongi, Minato-ku, Tokyo 106 (Japan)

    1997-04-01

    The stable injection locking of 0.8-{mu}m diode lasers with a double phase-conjugate mirror (DPCM) was achieved. Phase modulation by piezoelectric transducers allowed us to keep two input beams of the DPCM mutually incoherent during locking. We preserved the high performance of the DPCM and retained stable locking for more than an hour. {copyright} 1997 Optical Society of America

  4. Targeting doxorubicin encapsulated in stealth liposomes to solid tumors by non thermal diode laser

    OpenAIRE

    Ghannam, Magdy M.; El Gebaly, Reem; Fadel, Maha

    2016-01-01

    Background The use of liposomes as drug delivery systems is the most promising technique for targeting drug especially for anticancer therapy. Methods In this study sterically stabilized liposomes was prepared from DPPC/Cholesterol/PEG-PE encapsulated doxorubicin. The effect of lyophilization on liposomal stability and hence expiration date were studied. Moreover, the effect of diode laser on the drug released from liposomesin vitro and in vivo in mice carrying implanted solid tumor were also...

  5. Quasi zero-background tunable diode laser absorption spectroscopy employing a balanced Michelson interferometer.

    Science.gov (United States)

    Guan, Zuguang; Lewander, Märta; Svanberg, Sune

    2008-12-22

    Tunable diode laser spectroscopy (TDLS) normally observes small fractional absorptive reductions in the light flux. We show, that instead a signal increase on a zero background can be obtained. A Michelson interferometer, which is initially balanced out in destructive interference, is perturbed by gas absorption in one of its arms. Both theoretical analysis and experimental demonstration show that the proposed zero-background TDLS can improve the achievable signal-to-noise ratio.

  6. Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

    Directory of Open Access Journals (Sweden)

    Leticia Ferreira de Freitas BRIANEZZI

    Full Text Available Abstract Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC, water sorption (WS, and water solubility (WSB of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU]. Square-shaped specimens were prepared and assigned into 4 groups (n=5: SB and SU (control groups – no laser irradiation and SB-L and SU-L [SB and SU laser (L – irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5 of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10 were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm, irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2. Results Laser irradiation immediately before photopolymerization increased the DC (% of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3, only the dentin bonding system (DBS was a significant factor (pSU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

  7. [Evaluation of the efficacy of diode laser endocyclophotocoagulation combined with cataract surgery in glaucoma].

    Science.gov (United States)

    Ezzouhairi, S M

    2015-11-01

    Surgical techniques, which reduce the secretion of aqueous humor are underutilized in the surgical management of glaucoma; the diode laser coupled to an endoscope, endocyclophotocoagulation (ECP), is an emerging technology in the treatment of glaucoma. Indeed, thanks to its direct, focal and controllable approach to diode laser treatment of the ciliary processes, ECP renders this a safer technique compared to transscleral diode laser. We present preliminary results and an evaluation of the efficacy of ECP combined with cataract surgery performed at the Al Bassar clinic in Mohammedia, Morocco. We conducted a retrospective study on a series of 82 patients who underwent combined surgery: diode laser endocyclophotocoagulation and cataract for treatment of glaucoma during the period from December 2012 to July 2013. For this study, we recorded: age and gender of the patients, number and power of diode laser spots, pre- and postoperative intraocular pressure (IOP), and the number of anti-glaucoma treatments prescribed pre- and postoperatively (3 months minimum). Technically, a 20-gauge endo-ocular probe is inserted through the corneal incision used for phacoemulsification. The probe is equipped with a light source, a camera and a pulsed 810 nm laser beam; it is connected to an Endo-optiks type generator, which allows for direct visualization of the ciliary processes and their precise treatment. The surgical procedure is both simple and quick. Postoperative follow-up is unchanged from the management of cataract extraction by phacoemulsification. The average age in our series was 69.5 years (range 33-81 years), mean follow-up was 5.7 months. The reduction in intraocular pressure was 28.5%. In 40% of patients, a significant reduction in medications was noted, and in 20%, a total suspension of anti-glaucoma medications. No serious complications were noted in our series. This technique can perfectly fit into the medical, natural and/or surgical armamentarium medical, physical

  8. Roadside automobile emission monitoring with Peltier-cooled diode laser spectrometer

    Science.gov (United States)

    Kastner, Joachim F.; Sassenscheid, Karsten; Halford, B.; Lambrecht, Armin; Tacke, Maurus

    1997-05-01

    The use of catalytic converters in cars with gasoline engine results in a tremendous reduction of the emission of pollutant gases. The optimal operation of the exhaust treatment systems is being checked and maintained periodically, but there is always a significant percentage of cars with a malfunction of the catalytic converter causing a substantial percentage of the total emission. Roadside emission monitoring of individual cars in the running traffic could be used to indicate these gross polluters, arrange maintenance of their vehicles and thus reduce total emission. Present monitoring systems use non- dispersive IR spectroscopy. Other systems are based on mid- IR diode laser spectroscopy offering a higher signal to noise ratio, higher selectivity for detection of specific compounds and better optical quality for long open path measurements, but these systems depend on liquid nitrogen cooling. In this work a compact mid-IR (MIR) laser diode system for roadside measurements will be presented, that is cooled thermoelectrically using a Peltier element. Sensitivity and time resolution of the system have been determined and found to be suitable for detection of single gross polluters in the running traffic. The presented system demonstrates the feasibility of high sensitive, selective and fast field MIR laser diode spectroscopy together with ruggedness and low maintenance expense.

  9. Targeting doxorubicin encapsulated in stealth liposomes to solid tumors by non thermal diode laser.

    Science.gov (United States)

    Ghannam, Magdy M; El Gebaly, Reem; Fadel, Maha

    2016-04-05

    The use of liposomes as drug delivery systems is the most promising technique for targeting drug especially for anticancer therapy. In this study sterically stabilized liposomes was prepared from DPPC/Cholesterol/PEG-PE encapsulated doxorubicin. The effect of lyophilization on liposomal stability and hence expiration date were studied. Moreover, the effect of diode laser on the drug released from liposomesin vitro and in vivo in mice carrying implanted solid tumor were also studied. The results indicated that lyophilization of the prepared liposomes encapsulating doxorubicin led to marked stability when stored at 5 °C and it is possible to use the re-hydrated lyophilized liposomes within 12 days post reconstitution. Moreover, the use of low energy diode laser for targeting anticancer drug to the tumor cells is a promising method in cancer therapy. We can conclude that lyophilization of the liposomes encapsulating doxorubicin lead to marked stability for the liposomes when stored at 5 °C. Moreover, the use of low energy diode laser for targeting anticancer drug to the tumor cells through the use of photosensitive sterically stabilized liposomes loaded with doxorubicin is a promising method. It proved to be applicable and successful for treatment of Ehrlich solid tumors implanted in mice and eliminated toxic side effects of doxorubicin.

  10. Diffraction Limited 3.15 Microns Cascade Diode Lasers

    Science.gov (United States)

    2014-06-01

    moderately doped 25-nm-wide chirped AlSb /InAs superlattice. Conference Name: 2014 72nd Annual Device Research Conference (DRC) Conference Date...graded layer, 10-nm-thick GaSb layer and moderately doped 25-nm-wide chirped AlSb /InAs superlattice4. The laser heterostructure was grown by solid

  11. Diode Laser Surface Alloying of Armor Steel with Tungsten Carbide

    Directory of Open Access Journals (Sweden)

    Janicki D.

    2017-06-01

    Full Text Available Metal matrix composite (MMC surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction.

  12. Hair removal using an 810 nm gallium aluminum arsenide semiconductor diode laser: A preliminary study.

    Science.gov (United States)

    Williams, R M; Gladstone, H B; Moy, R L

    1999-12-01

    Laser hair removal is a popular treatment method for removing unwanted hair. Several laser systems are available for laser hair removal. The gallium aluminum arsenide semiconductor diode (GAASD) laser is one of the newer laser modalities to be studied. To evaluate the efficacy of the GAASD laser system in removing unwanted hair. Twenty-six patients with brown or black hair growth were treated with the GAASD laser at fluences of 20-80 J/cm2. Hair regrowth was measured 4 weeks after the first treatment, 4 weeks after the second treatment, 4 weeks after the third treatment, and 4 weeks, 8 weeks, and 8 months after the fourth treatment. GAASD laser treatment resulted in hair growth delay in all treated regions. Repeated laser treatments did not produce an increased number of vellus hairs. The percentage of hair reduction fluctuated between 5% and 13% with the second or third treatment averaging the highest percent reduction. In all cases, the percentage of hair reduction of the treatment sites evaluated at 8 months after the fourth treatment was less than both the second and third treatments (highest average percent reduction) and the fourth (last) treatment.

  13. Passive mode locking in a multisegment laser diode with an external cavity

    International Nuclear Information System (INIS)

    Andreeva, E V; Magnitskiy, Sergey A; Koroteev, Nikolai I; Salik, E; Feinberg, J; Starodubov, D S; Shramenko, M V; Yakubovich, S D

    1999-01-01

    The structure and operating conditions of multisegment laser (GaAl)As diodes with passive locking of the modes of an external cavity (bulk and fibre) were optimised. Regular trains of optical single pulses of picosecond duration were generated in a spectral range 850 - 860 nm. The peak power of these pulses was several watts and the repetition rate was near 1 GHz. Under certain conditions these output pulses were linearly chirped, i.e. they were suitable for subpicosecond time compression. Laboratory prototypes were made of miniature light-emitting modules with these characteristics. (lasers)

  14. Modelling and experimental study of temperature profiles in cw laser diode bars

    Science.gov (United States)

    Bezotosnyi, V. V.; Gordeev, V. P.; Krokhin, O. N.; Mikaelyan, G. T.; Oleshchenko, V. A.; Pevtsov, V. F.; Popov, Yu M.; Cheshev, E. A.

    2018-02-01

    Three-dimensional simulation is used to theoretically assess temperature profiles in proposed 10-mm-wide cw laser diode bars packaged in a standard heat spreader of the C - S mount type with the aim of raising their reliable cw output power. We obtain calculated temperature differences across the emitting aperture and along the cavity. Using experimental laser bar samples with up to 60 W of cw output power, the emission spectra of individual clusters are measured at different pump currents. We compare and discuss the simulation results and experimental data.

  15. Spin-injection-induced gain anisotropy in a polariton diode laser

    Science.gov (United States)

    Bhattacharya, Aniruddha; Bhattacharya, Pallab

    2018-02-01

    Optical effects arising from spin-induced gain anisotropy such as threshold reduction and emission intensity enhancement, hitherto unobserved in electrically injected polariton lasers, are predicted theoretically for a bulk GaN-based exciton-polariton diode laser operated with electrical injection of spin-polarized electrons. These phenomena are deduced from a simplified spin-dependent rate equation model. We also demonstrate an electrical excitation scheme, which can amplify the degree of a deterministic circular polarization of the output emission by an order of magnitude, compared to the injected electron spin polarization, above threshold.

  16. A low-cost photoacoustic microscopy system with a laser diode excitation

    Science.gov (United States)

    Wang, Tianheng; Nandy, Sreyankar; Salehi, Hassan S.; Kumavor, Patrick D.; Zhu, Quing

    2014-01-01

    Photoacoustic microscopy (PAM) is capable of mapping microvasculature networks in biological tissue and has demonstrated great potential for biomedical applications. However, the clinical application of the PAM system is limited due to the use of bulky and expensive pulsed laser sources. In this paper, a low-cost optical-resolution PAM system with a pulsed laser diode excitation has been introduced. The lateral resolution of this PAM system was estimated to be 7 µm by imaging a carbon fiber. The phantoms made of polyethylene tubes filled with blood and a mouse ear were imaged to demonstrate the feasibility of this PAM system for imaging biological tissues. PMID:25401019

  17. Preliminary results on diode-laser assisted vaporization of prostate tissue

    Science.gov (United States)

    Sroka, Ronald; Seitz, Michael; Reich, Oliver; Bachmann, Alexander; Steinbrecher, Verena; Ackermann, Alexander; Stief, Christian

    2007-07-01

    Introduction and objectives: The aim was to identify the capability and the laser parameter of under water tissue vaporisation by means of a diode laser (1470 nm). Afterwards the feasibility and postoperative clinical outcome of vaporization of the prostate was investigated. Method: After acquiring suitable laser parameters in in-vitro experiments using a perfused tissue model patients (n=10) suffering from bladder outlet obstruction due to benign prostatic hyperplasia (BPH) were treated by diode laser. Their clinical outcome, in terms of acceptance and post-operatively voiding were evaluated. The diode laser emitted light of the wavelength of 1470 nm at 50 W (Biolitec GmbH) and delivered to the tissue by means of a side-fire fibre introduced through a 24F continuous-flow cystoscope. Normal saline was used for irrigation with an additive of 1% ethanol. The prostatic lobes (volume range 35-80ml) were vaporized within the prostatic capsular using sweeping and push and pull technique. The mean time of laser application was 2400 sec (1220-4000 sec) resulting in applied energies of 121 kJ in the mean (range: 61-200kJ). Results: During laser treatment none of the 10 patients showed any significant blood loss or any fluid absorption (no ethanol uptake). Foley catheters were removed between 18 and 168 hours postoperatively (mean: 49.8h+/-46h). After removal of the catheter the mean peak urine flow rate increased from 8.9ml/s +/- 2.9ml/s pre-operatively in comparison to 15.7ml/s +/- 5 ml/s (p=0.049) post-operatively. 8/10 patients were satisfied with their voiding outcome. None of the patients showed appearance of urgency, dysuria, hematuria, or incontinence but two patients required re-catheterization. After a follow-up of 1month, 8/10 patients showed evidence of good results and are satisfied with the outcome. Two patients required consecutive TUR-P. After a follow-up of 6-month the 8 patients are still satisfied. Conclusions: This very early and limited experience using

  18. Improvement of the beam quality of a diode laser with two active broad-area segments

    DEFF Research Database (Denmark)

    Chi, Mingjun; Thestrup, B.; Mortensen, J.L.

    2003-01-01

    half of the freely running power of the laser was coupled out from the external cavity. The output power can be enhanced further by the feedback from the zeroth-order beam. The possibility of improving the beam quality further is discussed and a new double-external-cavity configuration is suggested.......The beam quality of a diode laser with two active segments was improved using an external cavity with collimating optics, a grating, and an output coupler. The beam quality of the output beam, which is the first-order diffractive beam from the grating, was improved by a factor of 2, and at least...

  19. 445-nm diode laser-assisted debonding of self-ligating ceramic brackets.

    Science.gov (United States)

    Stein, Steffen; Kleye, Alexander; Schauseil, Michael; Hellak, Andreas; Korbmacher-Steiner, Heike; Braun, Andreas

    2017-10-26

    This study determined the influence of irradiation on aesthetic ceramic brackets with a novel 445-nm diode laser prior to debonding on the bracket failure mode. Thirty ceramic brackets (In-Ovation® C, GAC) were standard-bonded to the oral and buccal planed and polished enamel surfaces of 15 caries-free human 3rd molars. Prior to study-blinded debonding, the brackets in the laser group were irradiated with the diode laser (SIROLaser Blue®, Sirona), while the irradiation was simulated within the conventional group. To determine the degree of enamel fractures and the adhesive remnant index (ARI) before debonding (T0), after debonding (T1) and after removal of the remaining composite using a rotating fraise (red ring, Comet) (T2), micrographs of the enamel surface at 10-fold and 20-fold magnifications were taken. Additionally, the enamel surface was investigated using seven randomly chosen samples from each group at every time point by SEM at 200-fold and 500-fold magnifications. In the laser group, the ARI-score was statistically significantly reduced (pdiode laser prior to debonding of ceramic brackets significantly changes bonding failure in terms of less remaining adhesive. This is of clinical importance as the risk of enamel fractures and chair time can be reduced.

  20. Apical leakage of three resin-based endodontic sealers after 810-nm-diode laser irradiation.

    Science.gov (United States)

    Moura-Netto, Cacio; Pinto, Tiago; Davidowicz, Harry; de Moura, Abilio Albuquerque Maranhão

    2009-12-01

    To evaluate the influence of 810-nm-diode laser irradiation, applied before root canal filling, on apical sealing ability of three different resin-based sealers (AH Plus, EndoRez, and RealSeal). Lasers have been widely used in endodontics. The dentin wall changes caused by laser irradiation could improve the sealing ability of endodontic cements. Sixty single-rooted human teeth were divided into six groups, according to the endodontic sealer used and previous 810-nm-diode laser irradiation. The protocol for laser irradiation was 2.5 W in a continuous wave, in scanning mode, with four irradiations per tooth. After sample preparation, they were analyzed according to apical leakage with silver nitrate impregnation. The RealSeal sealer achieved minimum leakage rates (1.24 mm), with significant differences at the 1% level (Tukey's test, plaser was used, there were also significant differences at the 5% level (plaser irradiation did not promote significant differences in apical leakage.

  1. Diode laser irradiation effects on the sealing ability of root canal sealers

    Science.gov (United States)

    Ribeiro, A. C.; Nogueira, G. E. C.; Mayer, M. P. A.; Antoniazzi, J. H.; Zezell, D. M.

    2010-06-01

    This study aimed to test the hypothesis that dentine alterations induced by 810 nm-diode laser may affect the interaction between root canal sealers and the dentin wall. Seventy-two single root human teeth were selected and root canals were enlarged with K-files. Dentine was treated with 0.5% NaOCl and 17% EDTA-T and irradiated (laser group) by diode laser (810 nm/ P = 2.5W/ I = 1989 W/cm2) or remained non-irradiated (control group). Six samples per group were analyzed by scanning electron microscopy (SEM). The remaining samples of each group were divided into three subgroups ( n = 10) and sealed with one of the tested sealers (N-Rickert/AHPlus™/Apexit®). Apical leakage was estimated by evaluating penetration of 0.5% methylene-blue dye. SEM analysis revealed that dentine at the apical third in irradiated samples was melted and fusioned whereas non-irradiated samples exhibited opened dentinal tubules. Despite the morphological changes induced by irradiation, laser did not affect the sealing ability of N-Rickert and AHPlusTM sealers. However, the length of apical leakage in roots filled with Apexit® was lower in irradiated root canals than in non-irradiated samples ( p laser irradiation may improve de sealing ability of Apexit®, a calcium hydroxide-based sealer, suggesting that improved sealing promoted by irradiation may represent an additional factor contributing to the endodontic clinical outcome.

  2. High Power Laser Diode Array Qualification and Guidelines for Space Flight Environments

    Science.gov (United States)

    Ott, Melanie N.; Eegholm, Niels; Stephen, Mark; Leidecker, Henning; Plante, Jeannette; Meadows, Byron; Amzajerdian, Farzin; Jamison, Tracee; LaRocca, Frank

    2006-01-01

    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. Modelling of a diode laser with a resonant grating of quantum wells and an external mirror

    International Nuclear Information System (INIS)

    Vysotskii, D V; Elkin, N N; Napartovich, A P; Kozlovskii, Vladimir I; Lavrushin, B M

    2011-01-01

    A three-dimensional numerical model of a diode laser with a resonant grating of quantum wells (QWs) and an external mirror is developed and used to calculate diode laser pulses that are long compared to the time of reaching a stationary regime and are short enough to neglect heating of the medium. The consistent solutions of the Helmholtz field equation and the system of diffusion equations for inversion in each QW are found. A source of charge carriers can be both an electron beam and a pump laser beam. The calculations yielded the longitudinal and radial profiles of the generated field, as well as its wavelength and power. The effective threshold pump current is determined. In the created iteration algorithm, the calculation time linearly increases with the number of QWs, which allows one to find the characteristics of lasers with a large number of QWs. The output powers and beam divergence angles of a cylindrical laser are calculated for different cavity lengths and pump spot radii. After calculating the fundamental mode characteristics, high-order modes were additionally calculated on the background of the frozen carrier distributions in the QW grating. It is shown that all the competing modes remain below the excitation threshold for the pump powers used in the experiment. The calculated and experimental data for the case of pumping by a nanosecond electron beam are qualitatively compared.

  4. 'In vitro' study of the efficacy of diode laser and LED irradiation during dental bleaching

    International Nuclear Information System (INIS)

    Barroso, Marcia Cristina da Silva

    2003-01-01

    This in vitro study evaluated the efficacy of LED and laser diode irradiation during the dental bleaching procedure, using two bleaching agents (Opalescence X-tra and HP Whiteness). The diode laser and the LED were operated in the continuous mode, with wavelength of 808 nm and 470 nm, respectively. The results of the irradiations were characterized with the CIELAB system calculating the L * a * b * values for the darkened and the bleached teeth (60 bovine incisors). This is to our knowledge the first time that light sources laser and LED are compared with respect to their whitening capability when applied to different agents. Significant differences in the chroma value are obtained for the two whitening agents and for the different light sources, too. Also, in terms of luminance, the combination of laser/ Whiteness HP showed significantly better results than when the same agent was used alone or in combination with LED. Best overall results are obtained with the combination of Whiteness HP and laser. (author)

  5. Investigation of diode-laser pumped thulium-doped fluoride lasers; Investigacao de lasers de floureto dopados com tulio e bombeados por diodo-laser

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Paulo Sergio Fabris de

    2006-07-01

    Tunable lasers emitting around 2.3 mum region are important in many areas, like gas detection, remote sensing and medical applications. Thulium has a large emission spectra around 2.3 mum with demonstrated tuning range of 2.2-2.45 mum using the YLF host. For efficient pump absorption, a high concentration sensitizer like ytterbium can be used. We demonstrate quasi-cw operation of the Yb:Tm:YLF laser, pumped at 960 nm with a 20 W diode bar achieving the highest output power reported so far of 620 mW. Simultaneous pumping of the 2.3 mm Yb:Tm:YLF laser at 685 nm and 960 nm is demonstrated, showing higher slope efficiency than 960 nm alone. Numerical simulations and analytical models show the best ratio of pump power between both wavelengths. (author)

  6. Fast photocatalytic degradation of methylene blue dye using a low-power diode laser.

    Science.gov (United States)

    Liu, Xianhua; Yang, Yulou; Shi, Xiaoxuan; Li, Kexun

    2015-01-01

    This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles). Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Remote detection of methane with a 1.66-microm diode laser.

    Science.gov (United States)

    Uehara, K; Tai, H

    1992-02-20

    High-sensitivity real-time remote detection of methane in air with a 1.66-microm distributed-feedback diode laser operating at room temperature is demonstrated by laboratory simulations. The laser current was modulated at a high frequency of ~5 MHz, and the laser-center frequency was locked onto a methane-absorption line. The laser light directed toward the probed region was received after one-way transmission or further reflection from a topographic target. The methane absorption was detected by the second-harmonic component in the optical-power variation. The minimum-detectable concentration-path-length product in the transmission scheme was 0.3 part in 10(6) m for a signal averaging time of 1.3 s. In the reflection scheme, the amount of methane could be measured from the ratio of the fundamental and second-harmonic signal intensities independently of the received power.

  8. Continuous-wave diode-pumped Yb 3+:LYSO tunable laser

    Science.gov (United States)

    Du, Juan; Liang, Xiaoyan; Xu, Yi; Li, Ruxin; Yan, Chengfeng; Zhao, Guangjun; Su, Liangbi; Xu, Jun; Xu, Zhizhan

    2007-01-01

    A new alloyed crystal, Yb:LYSO, has been grown by the Czochralski method in our institute for the first time, and its effective diode-pumped cw tunable laser action was demonstrated. The alloyed crystal retains excellent laser properties of LSO with reduced growth cost, as well as the favorable growth properties of YSO. With a 5-at.% Yb:LYSO sample, we achieved 2.84 W output power at 1085 nm and a slope efficiency of 63.5%. And its laser wavelength could be tuned over a range broader than 80nm, from 1030nm to 1111 nm. This is the broadest tunable range achieved for Yb:LYSO laser, as far as we know.

  9. Breath analysis using external cavity diode lasers: a review

    Science.gov (United States)

    Bayrakli, Ismail

    2017-04-01

    Most techniques that are used for diagnosis and therapy of diseases are invasive. Reliable noninvasive methods are always needed for the comfort of patients. Owing to its noninvasiveness, ease of use, and easy repeatability, exhaled breath analysis is a very good candidate for this purpose. Breath analysis can be performed using different techniques, such as gas chromatography mass spectrometry (MS), proton transfer reaction-MS, and selected ion flow tube-MS. However, these devices are bulky and require complicated procedures for sample collection and preconcentration. Therefore, these are not practical for routine applications in hospitals. Laser-based techniques with small size, robustness, low cost, low response time, accuracy, precision, high sensitivity, selectivity, low detection limit, real-time, and point-of-care detection have a great potential for routine use in hospitals. In this review paper, the recent advances in the fields of external cavity lasers and breath analysis for detection of diseases are presented.

  10. Database organization for computer-aided characterization of laser diode

    International Nuclear Information System (INIS)

    Oyedokun, Z.O.

    1988-01-01

    Computer-aided data logging involves a huge amount of data which must be properly managed for optimized storage space, easy access, retrieval and utilization. An organization method is developed to enhance the advantages of computer-based data logging of the testing of the semiconductor injection laser which optimize storage space, permit authorized user easy access and inhibits penetration. This method is based on unique file identification protocol tree structure and command file-oriented access procedures

  11. Novel short-pulse laser diode source for high-resolution 3D flash lidar

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2017-06-01

    Imaging based on laser illumination is present in various fields of applications such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified the recent years. Among the various technologies currently studied, automotive lidars are a fast-growing one due to their accuracy to detect a wide range of objects at distances up to a few hundreds of meters in various weather conditions. First commercialized devices for ADAS were laser scanners. Since then, new architectures have recently appeared such as solid-state lidar and flash lidar that offer a higher compactness, robustness and a cost reduction. Flash lidars are based on time-of-flight measurements, with the particularity that they do not require beam scanners because only one short laser pulse with a large divergence is used to enlighten the whole scene. Depth of encountered objects can then be recovered from measurement of echoed light at once, hence enabling real-time 3D mapping of the environment. This paper will bring into the picture a cutting edge laser diode source that can deliver millijoule pulses as short as 12 ns, which makes them highly suitable for integration in flash lidars. They provide a 100-kW peak power highly divergent beam in a footprint of 4x5 cm2 (including both the laser diode and driver) and with a 30-% electrical-to-optical efficiency, making them suitable for integration in environments in which compactness and power consumption are a priority. Their emission in the range of 800-1000 nm is considered to be eye safe when taking into account the high divergence of the output beam. An overview of architecture of these state-of-the-art pulsed laser diode sources will be given together with some solutions for their integration in 3D mapping systems. Future work leads will be discussed for miniaturization of the laser diode and drastic cost reduction.

  12. Diode Laser and Calcium Hydroxide for Elimination of Enterococcus Faecalis in Root Canal

    Directory of Open Access Journals (Sweden)

    Neda Naghavi

    2014-06-01

    Full Text Available Introduction: The ultimate goal of endodontic treatment is to eliminate the bacterial infection in the root canal system. While mechanical debridement combined with chemical irrigation removes the bulk of microorganisms, residual bacteria are readily detectable in approximately one-half of teeth just prior to obturation. Laser light can be used to destroy bacteria. This in vitro study was performed to evaluate the effect of diode laser and calcium hydroxide on mono-infected dental canals.Methods: Fifty five single-rooted human premolars were prepared and contaminated with Enterococcus faecalis. After three weeks of incubation, the samples were divided into three experimental groups (n = 15 and two control groups (n = 5. In the first and second groups, the teeth were rinsed for 5 min with either sterile saline or 5.25% NaOCl and irradiated with a 810-nm diode laser at 1.5 W output for 5 × 4s. In the third group, the teeth were rinsed with 5.25% NaOCl and then Ca(OH2 paste was inserted in the canals for 1 week. Intracanal bacterial sampling was done and the samples were plated to determine the CFU count. Results: 5.25% NaOCl plus laser was as effective as calcium hydroxide and significantly more effective than sterile saline (P>0.05 in elimination of E. faecalis. Complete elimination of E. faecalis was seen only for the one week calcium hydroxide treatment. Conclusion: Combination therapy with NaOCl irrigation and diode laser irradiation can be recommended as an effective treatment option for elimination of E. faecalis from the root canal system.

  13. Effects of atmospheric transmission of high power diode pumped alkali lasers

    Science.gov (United States)

    Rice, Christopher A.; Perram, Glen P.

    2013-03-01

    As diode pumped alkali lasers (DPAL) are scaled to powers exceeding 1 kW, the effects of atmospheric transmission, including thermal blooming, is explored. The cesium and rubidium lasers operate near 894 and 795 nm, respectively, in the vicinity of atmospheric water vapor absorption lines. The potassium laser line lies in the high rotational limit of the O2 X-b (0,0) band near 770 nm. We assess the effects of atmospheric transmission on high power propagation using the High Energy Laser End-to End Operational Simulation. HELEEOS uses the scaling laws of the Scaling the High energy laser And Relay Engagements (SHaRE) toolbox which is anchored to the wave optics code WaveTrain and all significant degradation effects, including thermal blooming due to molecular and aerosol absorption, scattering extinction, and optical turbulence, are represented in the model. The HELEEOS model enables the evaluation of uncertainty in low-altitude high energy laser engagements due to all major low altitude atmospheric effects to include physically-based representations of water clouds, fog, light rain, and aerosols. Worldwide seasonal, diurnal, and geographical spatial-temporal variability in key climatological parameters is organized into probability density function databases in HELEEOS using a variety of recently available resources to include the Extreme and Percentile Environmental Reference Tables (ExPERT) for 408 sites worldwide, the Surface Marine Gridded Climatology (SMGC) database which provides coverage over all ocean areas, the Master Database for Optical Turbulence Research in support of the Airborne Laser, and the Global Aerosol Data Set (GADS) used to provide worldwide aerosol densities. The spectral transmission model is anchored to field data from an open-path Tunable Diode Laser Absorption (TDLAS) system composed of narrow band (~300 kHz) diode laser fiber coupled to a 12" Ritchey-Chrétien transmit telescope. The ruggedized system has been field deployed and tested

  14. SETUP FOR MEASUREMENT OF THE PHOTOMETRIC, RADIOMETRIC, SPECTRAL AND SPATIAL CHARACTERISTICS OF RADIATION OF LASER DIODES AND LEDS IN THE SPECTRAL RANGE FROM 250 TO 900 NM

    Directory of Open Access Journals (Sweden)

    S. V. Nikanenka

    2015-01-01

    Full Text Available Information about principle of operation of the setup for measurement of the photometric, radiometric, spectral and spatial characteristics of radiation of laser diodes and LEDs in the spectral range from 250 to 900 nm constructed in the B.I. Stepanov Institute of Physics of NAS of Belarus and the results of its metrological certification are presented. New approaches to measure the averaged value of the luminance and spectral radiance LEDs and laser diodes, the spatial distribution of luminous intensity and power density of laser diodes radiation, the luminous intensity and radiant intensity LEDs and laser diodes

  15. All-optical flip-flop operation based on asymmetric active-multimode interferometer bi-stable laser diodes

    DEFF Research Database (Denmark)

    Jiang, H.; Chaen, Y.; Hagio, T.

    2011-01-01

    We demonstrate fast and low energy all optical flip-flop devices based on asymmetric active-multimode interferometer using high-mesa waveguide structure. The implemented devices showed high speed alloptical flip-flop operation with 25ps long pulses. The rising and falling times of the output sign...

  16. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Science.gov (United States)

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels.

  17. Selective removal of dental composite with a diode-pumped Er:YAG laser

    Science.gov (United States)

    Fried, William A.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Selective removal of dental composite with high precision is best accomplished using lasers operating at high pulse repetition rates focused to a small spot size. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to compare the ablation rates and selectivity of enamel and composite for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 30-50-μs and evaluate it's suitability for the selective removal of composite from tooth surfaces. The depth of ablation and changes in surface morphology were assessed using digital microscopy. The fluence range of 30-50 J/cm2 appeared optimal for the removal of composite, and damage to sound enamel was limited to less than 100-μm after the removal of composite as thick as 700-800-μm. Future studies will focus on the use of methods of feedback to further increase selectivity.

  18. Progress in 41Ca ultratrace determination by diode-laser-based RIMS

    International Nuclear Information System (INIS)

    Mueller, P.; Blaum, K.; Diel, S.; Geppert, Ch.; Wendt, K.; Bushaw, B.A.; Trautmann, N.

    2001-01-01

    We report on progress in development and application of 41 Ca ultratrace determination by diode-laser-based RIMS. Applications include biomedical isotope-tracer studies of human calcium kinetics, cosmochemical investigations of meteorites, environmental dosimetry and radiodating. Depending on the application, 41 Ca needs to be determined at isotopic abundance in the range of 10 -9 to 10 -15 relative to the major stable isotope 40 Ca. We use either a double- or triple-resonance excitation scheme and subsequent non-resonant photoionization of calcium atoms in a collimated atomic beam. All resonant steps are excited with narrow bandwidth extended cavity diode lasers, non-resonant photo-ionization is attained with either an argon ion laser or a CO 2 laser. The resulting photo-ions are detected with a quadrupole mass spectrometer. With double-resonance excitation, the optical isotopic selectivity for 41 Ca against 40 Ca is 2x10 4 , while the triple-resonance scheme provides optical selectivity of more than 10 9 . By adding the third resonant step, overall detection efficiency increases from 1x10 -6 to 5x10 -5 and the detection limit for relative 41 Ca abundance improves from 5x10 -10 to 2x10 -13 . Both schemes have been applied to various sample types and accuracy and reproducibility of the resulting 41 Ca/ 40 Ca isotope ratios have been determined to be better than 5%

  19. To compare the gingival melanin repigmentation after diode laser application and surgical removal

    Directory of Open Access Journals (Sweden)

    Gaurav Mahajan

    2017-01-01

    Full Text Available Aim: The aim of the present study is to compare the gingival melanin repigmentation after diode laser application and surgical removal done by scraping with Kirkland knife. Materials and Methods: This study was a randomized split-mouth study where 10 patients presenting with unattractive, diffuse, dark brown to black gingival discoloration on the facial aspect of the maxillary gingiva were treated by diode laser application and surgical removal and followed up for 3-, 6-, and 9-month intervals. Results: The results showed a statistically significant difference in repigmentation between the groups at the interval of 3 months (P = 0.040, but the difference was statistically not significant at 6 months (P = 0.118 and 9 months (P = 0.146. On surgically treated sites, all cases showed repigmentation of the gingiva, but in laser treated, there were two individuals which did not show repigmentation of the gingiva even at the end of 9-month observation time. Conclusion: The incidence of repigmentation was slightly less in laser-treated sites as compared to surgical depigmentation although the difference was statistically significant only up to 3 months.

  20. All-diode-laser cooling of Sr+ isotope ions for analytical applications

    Science.gov (United States)

    Jung, Kyunghun; Yamamoto, Kazuhiro; Yamamoto, Yuta; Miyabe, Masabumi; Wakaida, Ikuo; Hasegawa, Shuichi

    2017-06-01

    Trapping and cooling of Sr+ isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr+ ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88Sr+ ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84Sr+ and 86Sr+, were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2S1/2 → 5p 2P1/2) of Sr+ ions were determined to be +371(8) MHz for Δν84-88 and +169(8) MHz for Δν86-88. In the case of the repumping transition (4d 2D3/2 → 5p 2P1/2), Δν84-88 and Δν86-88 were measured to be -833(6) and -400(5) MHz, respectively. These values are in good agreement with previously reported values.

  1. Efficient second harmonics generation of a laser-diode-pumped Nd:YAG laser and its applications. Laser diode reiki Nd:YAG laser no kokoritsu daini kochoha hassei to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, S.; Oka, M. (Sony Corp., Tokyo (Japan))

    1991-08-10

    Stabilization of the second harmonics in a laser-diode-pumped Nd:YAG laser and its application are described. The laser is a quantum noise limiting laser, in which a mode competing noise is generated from an interaction between the laser medium Nd:YAG and the type II nonlinear optical crystal KTiOPO{sub 4} when generating a second harmonics in the resonator. However, the quantum noise limiting second harmonics was obtained by means of inserting (1/4) wave length plate in the resonator to release the bond between two intersecting inherent polarization modes. This stabilized green laser is of a single lateral mode is nearly free of aberration. Therefore, an optical disc prototype having three times as much of the currently used density was made using an objective lens having high number of openings to collect lights, which was verified capable of regeneration at a high signal to noise ratio. In addition, higher output is possible by means of parallelizing the excitation, and high output is realized from edge excitation at a fiber bundle. 18 refs., 3 figs.

  2. 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.

    2010-01-01

    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...

  3. Microphone triggering circuit for elimination of mechanically induced frequency-jitter in diode laser spectrometers: implications for quantitative analysis.

    Science.gov (United States)

    Sams, R L; Fried, A

    1987-09-01

    An electronic timing circuit using a microphone triggering device has been developed for elimination of mechanically induced frequency-jitter in diode laser spectrometers employing closed-cycle refrigerators. Mechanical compressor piston shocks are detected by the microphone and actuate an electronic circuit which ultimately interrupts data acquisition until the mechanical vibrations are completely quenched. In this way, laser sweeps contaminated by compressor frequency-jitter are not co-averaged. Employing this circuit, measured linewidths were in better agreement with that calculated. The importance of eliminating this mechanically induced frequency-jitter when carrying out quantitative diode laser measurements is further discussed.

  4. Bevacizumab compared with Diode Laser in stage 3 posterior retinopathy of prematurity: a 5 year follow-up

    LENUS (Irish Health Repository)

    O’Keeffe, N

    2016-02-01

    We conducted a prospective randomized study to compare outcomes of intravitreal Bevacizumab versus diode laser in thirty eyes of fifteen premature babies with zone 1 or posterior zone 2 retinopathy of prematurity (ROP). We recorded complications, regression\\/reactivation of ROP, visual outcome, refractive error and systemic complications. The Bevacizumab-treated eyes showed rapid regression of the ROP with resolution of plus disease and flattening of the ridge at 48 hours post injection. In 3 Bevacizumab-treated eyes, reactivation occurred and were treated with laser (3 eyes) or a further Bevacizumab injection (1 eye). Of the diode laser treated eyes, one showed progression and was treated with Bevacizumab. At 5-year follow-up, good outcomes were observed in both treatment groups. However, less myopia was found in the Bevacizumab compared with the diode laser treated eyes.

  5. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2011-01-01

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest...... output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2- values of the laser with lowest spatial coherence. The principle...... of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future....

  6. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

    Science.gov (United States)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-01-17

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future.

  7. Study on the near-field non-linearity (SMILE) of high power diode laser arrays

    Science.gov (United States)

    Zhang, Hongyou; Jia, Yangtao; Li, Changxuan; Zah, Chung-en; Liu, Xingsheng

    2018-02-01

    High power laser diodes have been found a wide range of industrial, space, medical applications, characterized by high conversion efficiency, small size, light weight and a long lifetime. However, due to thermal induced stress, each emitter in a semiconductor laser bar or array is displaced along p-n junction, resulting of each emitter is not in a line, called Near-field Non-linearity. Near-field Non-linearity along laser bar (also known as "SMILE") determines the outcome of optical coupling and beam shaping [1]. The SMILE of a laser array is the main obstacle to obtain good optical coupling efficiency and beam shaping from a laser array. Larger SMILE value causes a larger divergence angle and a wider line after collimation and focusing, respectively. In this letter, we simulate two different package structures based on MCC (Micro Channel Cooler) with Indium and AuSn solders, including the distribution of normal stress and the SMILE value. According to the theoretical results, we found the distribution of normal stress on laser bar shows the largest in the middle and drops rapidly near both ends. At last, we did another experiment to prove that the SMILE value of a laser bar was mainly affected by the die bonding process, rather than the operating condition.

  8. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy

    Science.gov (United States)

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L.; Kobayashi, Hisataka

    2016-01-01

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT. PMID:26885688

  9. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy.

    Science.gov (United States)

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L; Kobayashi, Hisataka

    2016-03-22

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT.

  10. Preliminary results with sutured colonic anastomoses reinforced with dye-enhanced fibrinogen and a diode laser

    Science.gov (United States)

    Libutti, Steven K.; Williams, Matthew R.; Oz, Mehmet C.; Forde, Kenneth A.; Bass, Lawrence S.; Weinstein, Samuel; Auteri, Joseph S.; Treat, Michael R.; Nowygrod, Roman

    1991-07-01

    A common cause of morbidity in patients recovering from bowel surgery is leakage from colonic anastomoses. A technique utilizing a laser activated protein solder to strengthen colonic anastomoses in a canine model was evaluated. Following creation of six single-layer interrupted suture anastomoses in four dogs, a protein solder consisting of indocyanine green dye and fibrinogen was topically appied to the serosal surface and exposed to 808 nm continuous wave diode laser energy. Immediately following anastomosis, the mean leakage pressure of sutures alone was 129 +/- 14 mm hg (n equals 6), while the mean leakage pressure of sutures reinforced with the laser welded solder was 312 +/- 32 mm hg (n equals 6) (p anastomoses without causing appreciable thermal injury to surrounding tissues.

  11. Performance improvements in temperature reconstructions of 2-D tunable diode laser absorption spectroscopy (TDLAS)

    Science.gov (United States)

    Choi, Doo-Won; Jeon, Min-Gyu; Cho, Gyeong-Rae; Kamimoto, Takahiro; Deguchi, Yoshihiro; Doh, Deog-Hee

    2016-02-01

    Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy (TDLAS). Multiplicative Algebraic Reconstruction Technique (MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique (ART) algorithm.

  12. Stability of the single-mode output of a laser diode array with phase conjugate feedback

    DEFF Research Database (Denmark)

    Juul Jensen, S.; Løbel, M.; Petersen, P.M.

    2000-01-01

    . The output power and the center wavelength are found to be extremely stable in a 100 h stability measurement. External feedback of the output beam into the laser is seen to decrease both the spatial and the temporal coherence of the output significantly. We outline an approach to obtain a stable single......The stability of the output of a single-mode laser diode array with frequency selective phase conjugate feedback has been investigated experimentally. Both the long-term stability of the laser output and the sensitivity to feedback generated by external reflection of the output beam are examined......-mode output when external feedback is present using spatial filtering in the path of the output beam. (C) 2000 American Institute of Physics....

  13. ToF-SIMS characterization of robust window material for use in diode pumped alkali lasers

    Science.gov (United States)

    Fletcher, Aaron; Turner, David; Fairchild, Steven; Rice, Christopher; Pitz, Gregory

    2018-03-01

    Developments in diode pumped alkali laser (DPAL) systems have been impeded because of the catastrophic failure of laser windows. The window's failure is caused by localized laser-induced heating of window material. This heating is believed to occur due to increases in absorption on or near the surface of the window. This increase is believed to be caused by either adsorption of carbon-based soot from the collisional gas or by the diffusion of rubidium into the bulk material. The work presented here will focus on the diffusion of Rb into the bulk window materials and will strive to identify a superior material to use as windows. The results of this research indicate that aluminum oxynitride (ALON), sapphire, MgAl2O4 (spinel), and ZrO2 are resistant to alkali-induced changes in optical properties.

  14. Universal gate-set for trapped-ion qubits using a narrow linewidth diode laser

    International Nuclear Information System (INIS)

    Akerman, Nitzan; Navon, Nir; Kotler, Shlomi; Glickman, Yinnon; Ozeri, Roee

    2015-01-01

    We report on the implementation of a high fidelity universal gate-set on optical qubits based on trapped 88 Sr + ions for the purpose of quantum information processing. All coherent operations were performed using a narrow linewidth diode laser. We employed a master-slave configuration for the laser, where an ultra low expansion glass Fabry–Perot cavity is used as a stable reference as well as a spectral filter. We characterized the laser spectrum using the ions with a modified Ramsey sequence which eliminated the affect of the magnetic field noise. We demonstrated high fidelity single qubit gates with individual addressing, based on inhomogeneous micromotion, on a two-ion chain as well as the Mølmer–Sørensen two-qubit entangling gate. (paper)

  15. Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

    Science.gov (United States)

    Savage-Leuchs,; Matthias, P [Woodinville, WA

    2009-05-26

    Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

  16. Analysis of shade, temperature and hydrogen peroxide concentration during dental bleaching: in vitro study with the KTP and diode lasers.

    Science.gov (United States)

    Fornaini, C; Lagori, G; Merigo, E; Meleti, M; Manfredi, M; Guidotti, R; Serraj, A; Vescovi, P

    2013-01-01

    Many dental bleaching techniques are now available, several of them using a laser source. However, the literature on the exact role of coherent light in the biochemical reaction of the whitening process is very discordant. The aims of this in vitro study were: (1) to compare two different laser sources, a KTP laser with a wavelength of 532 nm and a diode laser with a wavelength of 808 nm, during dental bleaching, and (2) to investigate the relationships among changes in gel temperature, tooth shade and hydrogen peroxide (HP) concentration during laser irradiation. Altogether, 116 bovine teeth were bleached using a 30% HP gel, some of them with gel only and others with gel plus one of the two lasers (532 or 808 nm) at two different powers (2 and 4 W). The KTP laser produced a significant shade variation with a minimal temperature increase. The diode laser led to a higher temperature increase with a greater reduction in HP concentration, but the change in shade was only statistically significant with a power of 4 W. At a power of 2 W, the KTP laser caused a greater change in shade than the diode laser. No significant correlations were found among temperature, HP concentration and shade variation. The KTP laser appears to provide better results with less dangerous thermal increases than the diode laser. This might call into question most of the literature affirming that the action of laser bleaching is by increasing the gel temperature and, consequently, the speed of the redox reaction. Further study is required to investigate the correlations between the parameters investigated and efficacy of the bleaching process.

  17. Diode laser for endodontic treatment: investigations of light distribution and disinfection efficiency

    Science.gov (United States)

    Stock, Karl; Graser, Rainer; Udart, Martin; Kienle, Alwin; Hibst, Raimund

    2011-03-01

    Diode lasers are used in dentistry mainly for oral surgery and disinfection of root canals in endodontic treatment. The purpose of this study was to investigate and to improve the laser induced bacteria inactivation in endodontic treatment. An essential prerequisite of the optimization of the irradiation process and device is the knowledge about the determinative factors of bacteria killing: light intensity? light dosis? temperature? In order to find out whether high power NIR laser bacterial killing is caused by a photochemical or a photothermal process we heated bacteria suspensions of E. coli K12 by a water bath and by a diode laser (940 nm) with the same temporal temperature course. Furthermore, bacteria suspensions were irradiated while the temperature was fixed by ice water. Killing of bacteria was measured via fluorescence labeling. In order to optimize the irradiation of the root canal, we designed special fiber tips with radial light emission characteristic by optical ray tracing simulations. Also, we calculated the resulting light distribution in dentin by voxelbased Monte Carlo simulations. Furthermore, we irradiated root canals of extracted human teeth using different fiber tip geometries and measured the resulting light and heat distribution by CCD-camera and thermography. Comparison of killing rates between laser and water based heating shows no significant differences, and irradiation of ice cooled suspensions has no substantial killing effect. Thus, the most important parameter for bacterial killing is the maximum temperature. Irradiation of root canals using fiber tips with radial light emission results in a more defined irradiated area with minor irradiation of the apex and higher intensity and therefore higher temperature increase on root canal surface. In conclusion, our experiments show that at least for E. coli bacteria inactivation by NIR laser irradiation is solely based on a thermal process and that heat distribution in root canal can be

  18. Viability of fibroblasts cultured under nutritional stress irradiated with red laser, infrared laser, and red light-emitting diode

    Science.gov (United States)

    Volpato, Luiz Evaristo Ricci; de Oliveira, Rodrigo Cardoso; Espinosa, Mariano Martinez; Bagnato, Vanderley Salvador; Machado, Maria A. A. M.

    2011-07-01

    Phototherapy is noninvasive, painless and has no known side effect. However, for its incorporation into clinical practice, more well-designed studies are necessary to define optimal parameters for its application. The viability of fibroblasts cultured under nutritional stress irradiated with either a red laser, an infrared laser, or a red light-emitting diode (LED) was analyzed. Irradiation parameters were: red laser (660 nm, 40 mW, 1 W/cm2), infrared laser (780 nm, 40 mW, 1 W/cm2), and red LED (637 +/- 15 nm, 40 mW, 1 W/cm2). All applications were punctual and performed with a spot with 0.4 mm2 of diameter for 4 or 8 s. The Kruskal-Wallis test and analysis of variance of the general linear model (p phototherapy with low-intensity laser and LED showed no toxicity at the cellular level. It even stimulated methylthiazol tetrazolium assay (MTT) conversion and neutral red uptake of fibroblasts cultured under nutritional stress, especially in the group irradiated with infrared laser (p = 0.004 for MTT conversion and p phototherapy used, it can be concluded that phototherapy stimulated the viability of fibroblasts cultured under nutritional deficit resembling those found in traumatized tissue in which cell viability is reduced.

  19. Epi-detecting label-free multimodal imaging platform using a compact diode-pumped femtosecond solid-state laser

    Science.gov (United States)

    Andreana, Marco; Le, Tuan; Hansen, Anders K.; Verhoef, Aart J.; Jensen, Ole B.; Andersen, Peter E.; Slezak, Paul; Drexler, Wolfgang; Fernández, Alma; Unterhuber, Angelika

    2017-09-01

    We have developed an epi-detected multimodal nonlinear optical microscopy platform based on a compact and cost-effective laser source featuring simultaneous acquisition of signals arising from hyperspectral coherent anti-Stokes Raman scattering (CARS), two-photon fluorescence, and second harmonic generation. The laser source is based on an approach using a frequency-doubled distributed Bragg reflector-tapered diode laser to pump a femtosecond Ti:sapphire laser. The operational parameters of the laser source are set to the optimum trade-off between the spectral and temporal requirements for these three modalities, achieving sufficient spectral resolution for CARS in the lipid region. The experimental results on a biological tissue reveal that the combination of the epi-detection scheme and the use of a compact diode-pumped femtosecond solid-state laser in the nonlinear optical microscope is promising for biomedical applications in a clinical environment.

  20. The Effect of Diode Laser on Planktonic Enterococcus faecalis in Infected Root Canals in an Ex Vivo Model.

    Science.gov (United States)

    Cretella, Gilda; Lajolo, Carlo; Castagnola, Raffaella; Somma, Francesco; Inchingolo, MariaTeresa; Marigo, Luca

    2017-04-01

    This study examined the bactericidal effect of diode laser irradiation against intracanal Enterococcus faecalis. m total of 128 extracted single-rooted and single-canal teeth were treated with ProTaper instruments (Dentsply Maillefer, Ballaigues, Switzerland). A total of 120 root canals were inoculated with E. faecalis for 21 days, and the samples were randomly divided into five groups: Group 1 (n = 24) samples were irrigated with only saline solution (positive controls); Group 2 (n = 24) was treated with only 5.25% sodium hypochlorite; Group 3 (n = 24) was irrigated with saline solutions activated by diode laser; Group 4 (n = 24) was treated with 5.25% sodium hypochlorite activated by diode laser; and Group 5 (n = 24) was irrigated with saline solution with methylene blue dye activated by the diode laser Fox (Sweden & Martina, Padova, Italy); additionally, eight teeth were not contaminated and their canals were irrigated with saline solution and used as a negative control. The Uro-Quick system was used to determine the microbial residual charge. The data were analyzed using Pearson's chi-square test (p  0.001). Evidence indicates that the diode laser was not more effective than sodium hypochlorite in reducing free bacteria.

  1. Numerical analysis of high-power broad-area laser diode with improved heat sinking structure using epitaxial liftoff technique

    Science.gov (United States)

    Kim, Younghyun; Sung, Yunsu; Yang, Jung-Tack; Choi, Woo-Young

    2018-02-01

    The characteristics of high-power broad-area laser diodes with the improved heat sinking structure are numerically analyzed by a technology computer-aided design based self-consistent electro-thermal-optical simulation. The high-power laser diodes consist of a separate confinement heterostructure of a compressively strained InGaAsP quantum well and GaInP optical cavity layers, and a 100-μm-wide rib and a 2000-μm long cavity. In order to overcome the performance deteriorations of high-power laser diodes caused by self-heating such as thermal rollover and thermal blooming, we propose the high-power broad-area laser diode with improved heat-sinking structure, which another effective heat-sinking path toward the substrate side is added by removing a bulk substrate. It is possible to obtain by removing a 400-μm-thick GaAs substrate with an AlAs sacrificial layer utilizing well-known epitaxial liftoff techniques. In this study, we present the performance improvement of the high-power laser diode with the heat-sinking structure by suppressing thermal effects. It is found that the lateral far-field angle as well as quantum well temperature is expected to be improved by the proposed heat-sinking structure which is required for high beam quality and optical output power, respectively.

  2. 80-W cw TEM{sub 00} IR beam generation by use of a laser-diode-side-pumped Nd:YAG rod laser

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Susumu; Fujikawa, Shuichi; Yasui, Koji [Mitsubishi Electric Corp. Amagasaki, Hyogo (Japan). Advanced Technology R and D Center

    1998-03-01

    We have demonstrated high-efficient and high-power operation of a diode-side-pumped Nd:YAG rod laser. The laser has a simple and scalable configuration consisting of a diffusive pumping reflector and an advanced cavity configuration for polarization-dependent bifocusing compensation. (author)

  3. Treatment of inflammatory facial acne vulgaris with combination 595-nm pulsed-dye laser with dynamic-cooling-device and 1,450-nm diode laser.

    Science.gov (United States)

    Glaich, Adrienne S; Friedman, Paul M; Jih, Ming H; Goldberg, Leonard H

    2006-03-01

    The 585-nm pulsed-dye laser and the 1,450-nm diode laser have been found effective for the treatment of mild-to-moderate inflammatory facial acne. This study was designed to evaluate the efficacy and safety of the combined treatment with the 595-nm pulsed-dye laser and the 1,450-nm diode laser for inflammatory facial acne. Fifteen patients with inflammatory facial acne were treated with a combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser. Patients' subjective response to treatment was evaluated regarding improvement in acne, acne scarring, oiliness, and redness of the skin. All patients had reductions in acne lesion counts. Mean lesion counts decreased 52% (P < 0.01), 63% (P < 0.01), and 84% (P < 0.01) after one, two, and three treatments, respectively. Patients described moderate-to-marked improvement in acne, acne scarring, and post-inflammatory erythema. Adverse effects were limited to mild, transient erythema. The combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser is safe and effective for the treatment of inflammatory facial acne, acne scarring, and post-inflammatory erythema. 2005 Wiley-Liss, Inc.

  4. Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

    Science.gov (United States)

    Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

    1988-01-01

    Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

  5. 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

    2011-01-13

    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

  6. Bistable Reflective Etalon (BRET)

    National Research Council Canada - National Science Library

    Shellenbarger, Zane

    2003-01-01

    This project designed, fabricated, and characterized normal-incidence etalon structures at 1550 nm wavelength operation for application, as bistable elements, to photonic analog-to-digital conversion...

  7. Simple, low-noise piezo driver with feed-forward for broad tuning of external cavity diode lasers

    Science.gov (United States)

    Doret, S. Charles

    2018-02-01

    We present an inexpensive, low-noise (diode lasers. This simple driver improves upon many commercially available drivers by incorporating circuitry to produce a "feed-forward" signal appropriate for making simultaneous adjustments to the piezo voltage and laser current, enabling dramatic improvements in a mode-hop-free laser frequency tuning range. We present the theory behind our driver's operation, characterize its output noise, and demonstrate its use in absorption spectroscopy on the rubidium D1 line.

  8. Efficient energy extraction from a diode-pumped Q-switched Tm,Ho:YLiF4 laser

    Science.gov (United States)

    Mcguckin, B. T.; Menzies, R. T.; Hemmati, H.

    1991-01-01

    The operation of a diode-laser pumped thulium, holmium yttrium-lithium-fluoride laser (Tm,Ho:YLF) in Q-switched mode is reported. Output energies of 200 microjoules in pulses of 22 ns duration are recorded at Q-switch frequencies commensurate with an effective upper laser level lifetime of 6 ms. This lifetime is appreciably longer than that observed in other hosts permitting stored energy extraction of 64 percent, close to the projected maximum performance from these materials.

  9. Effect of diode laser irradiation on compressive strength of dental amalgam.

    Science.gov (United States)

    Tabari, Mitra; Fekrazad, Reza; Alaghemand, Homayoun; Hamzeh, Mahtab

    2017-04-01

    One of the biggest disadvantages of dental amalgam is that gaining its ultimate strength is a slow process. The use of a rapid-setting amalgam with high early compressive strength could be a better option in preventing early fractures in pediatric dentistry. The aim of this study was to determine the effect of diode laser irradiation on compressive strength of dental amalgam. A case-control study was performed on 180 amalgam samples made at the Tehran Dental Material Research Center in 2014. Fifteen and thirty minute compressive strength of regular setting and fast setting amalgams were measured as control. In case groups, the samples were irradiated by 810nm diode laser with power of 1 and 2 watt and in pulsed and continuous mode, and compressive strength was measured after 15 and 30 minutes. Statistical analysis was performed with SPSS 18 using one and two way ANOVA and Scheffe multiple comparisons test and pamalgam irradiated by 2 watt laser was significantly more than fast-setting control group (pdental amalgam especially in the first 15 minutes.

  10. Micro packaging of hermetic seal mini dual in line laser diode module for aerospace applications

    Science.gov (United States)

    Kazemi, Alex A.; Chan, Eric; Koshinz, Dennis

    2014-09-01

    Normally, reliable, reproducible, high-yield packaging technologies are essential for meeting the cost, performance, and service objectives for the harsh environment of space applications. This paper describes a new improved micro packaging method of hermetic seal mini-DIL (dual in line) laser diode module. The problem of using a softer solder resulted in failure mechanisms observed in the mini-DIL laser diode module based laser firing unit (LFU) for ordinance ignition of a missile system. These failures included: (1) failure in light output pulse power, (2) fiber pigtail damage inside the package snout which caused low LFU production yield. Our distinctive challenge for this project is the micro packaging of mini-DIL. For this package a new technique for the hermetic sealing using a micro-soldering process was developed. The process is able to confine the solder seal to a small region inside the snout near the fiber feed-through hole on the wall of the mini-DIL package. After completing the development, which included temperature and thermal cycling, X-rays analysis showed the new method had no fiber damage after the microsoldering seal. The new process resulted in 100% success in the packaging design and was granted a patent for the innovative development.

  11. High repetition rate, high peak power, diode pumped Tm:YLF laser

    Science.gov (United States)

    Jabczynski, J. K.; Gorajek, Ł.; Zendzian, W.; Kwiatkowski, J.; Jelínková, H.; Šulc, J.; Němec, M.

    2009-02-01

    The room-temperature, water-cooled, diode pumped Tm:YLF laser head was elaborated and examined. For pumping the fiber coupled (0.2 mm core diameter) 25-W laser diode bar emitting at 792-nm wavelength was deployed. Near 5 W of CW output power and 25% slope efficiency was demonstrated in a short, 70-mm long resonator. Tuning in 1845-1935 nm wavelength range by means of 2-plate Lyot filter was demonstrated only in free-running regime. The fused silica acousto-optic modulator with above 80% diffraction efficiency for 25-W power of RF was deployed as the Q-switch for such a laser. In the best case of Q-switching regime, up to 10-mJ output energy with 47-ns pulse duration, 220 kW peak power was demonstrated for 133 Hz. For higher repetition rate of 2 kHz, 12 kW peak power with 2.5 W of average power was achieved.

  12. Effect of diode laser irradiation on compressive strength of dental amalgam

    Science.gov (United States)

    Tabari, Mitra; Fekrazad, Reza; Alaghemand, Homayoun; Hamzeh, Mahtab

    2017-01-01

    Introduction One of the biggest disadvantages of dental amalgam is that gaining its ultimate strength is a slow process. The use of a rapid-setting amalgam with high early compressive strength could be a better option in preventing early fractures in pediatric dentistry. The aim of this study was to determine the effect of diode laser irradiation on compressive strength of dental amalgam. Methods A case-control study was performed on 180 amalgam samples made at the Tehran Dental Material Research Center in 2014. Fifteen and thirty minute compressive strength of regular setting and fast setting amalgams were measured as control. In case groups, the samples were irradiated by 810nm diode laser with power of 1 and 2 watt and in pulsed and continuous mode, and compressive strength was measured after 15 and 30 minutes. Statistical analysis was performed with SPSS 18 using one and two way ANOVA and Scheffe multiple comparisons test and plaser irradiation led to a significant increase in compressive strength compared to regular setting control groups. Fifteen minutes-compressive strength of regular-setting amalgam irradiated by 2 watt laser was significantly more than fast-setting control group (plaser can significantly increase the compressive strength of dental amalgam especially in the first 15 minutes. PMID:28607639

  13. Antimicrobial photodynamic therapy using Indocyanine green and near-infrared diode laser in reducing Entrerococcus faecalis.

    Science.gov (United States)

    Beltes, Charis; Sakkas, Hercules; Economides, Nikolaos; Papadopoulou, Chrissanthy

    2017-03-01

    The use of Antimicrobial Photodynamic Therapy (aPDT) has been suggested as an adjuvant method to eliminate facultative bacteria during root canal disinfection. The purpose of this preliminary in vitro study was to determine whether the light-activated antimicrobial agent, Indocyanine green (ICG), could be used as photosensitizer and kill Enterococcus faecalis strain under planktonic conditions when irradiated with near-infared (NIR) diode laser emitting in 810nm wavelength. Planktonic suspension containing Enterococcus faecalis strain was divided into nine experimental groups: (1) aPDT with ICG and laser (medium energy fluence), (2) aPDT with ICG and laser (high energy fluence), (3) only ICG without laser activation, (4) only laser emission without ICG (5) 2.5% Sodium hypochlorite (NaOCl) as irrigant, (6) 2.5% NaOCl and aPDT with ICG and laser, (7) 2.0% Chlorhexidine gluconate (CHX) as irrigant (8) No treatment (positive control), (9) No bacterial biofilm growth (negative control). The samples were incubated for 7days and colony-forming units (CFUs) were determined to evaluate bacterial viability. The microbiological test revealed that aPDT groups, regardless the overall power, showed significant lower mean log 10 CFU levels, than groups 3, 4 and 7 (plaser may be a novel supplement in aPDT and provide better disinfection during endodontic treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. A pin diode x-ray camera for laser fusion diagnostic imaging: Final technical report

    International Nuclear Information System (INIS)

    Jernigan, J.G.

    1987-01-01

    An x-ray camera has been constructed and tested for diagnostic imaging of laser fusion targets at the Laboratory for Laser Energetics (LLE) of the University of Rochester. The imaging detector, developed by the Hughes Aircraft Company, is a germanium PIN diode array of 10 x 64 separate elements which are bump bonded to a silicon readout chip containing a separate low noise amplifier for each pixel element. The camera assembly consists of a pinhole alignment mechanism, liquid nitrogen cryostat with detector mount and a thin beryllium entrance window, and a shielded rack containing the analog and digital electronics for operations. This x-ray camera has been tested on the OMEGA laser target chamber, the primary laser target facility of LLE, and operated via an Ethernet link to a SUN Microsystems workstation. X-ray images of laser targets are presented. The successful operation of this particular x-ray camera is a demonstration of the viability of the hybrid detector technology for future imaging and spectroscopic applications. This work was funded by the Department of Energy (DOE) as a project of the National Laser Users Facility (NLUF)

  15. Monolithic wide tunable laser diodes for gas sensing at 2100 nm

    Science.gov (United States)

    Koslowski, Nicolas; Heger, Andreas; Roessner, Karl; Legge, Michael; Koeth, Johannes; Hildebrandt, Lars

    2013-03-01

    Novel monolithic widely tunable laser diodes in the 2.1μm wavelength region based on GaSb / AlGaAsSb are presented. Using the concept of a lateral binary superimposed (BSG) grating structures and multisegment Verniertuning, stable single-mode output is realized at discrete wavelength channels in the 2060 nm - 2140 nm region. A total tuning above 80 nm in six channels is demonstrated. In every wavelength channel, the output wavelength can be tuned by current and temperature. Each wavelength channel offers up to 6 nm of mode hop free tuning, making this novel widely tunable laser highly attractive as a monolithic light source for multiple-gas sensing or liquid detection purposes. The wavelength channels can be arbitrarily placed within the material gain allowing BSG lasers to sweep e.g. over several gas absorption line within 80 nm. Within a wavelength channel, the widely tunable lasers show DFB like spectral performance with average side-mode suppression-ratios above 40 dB, output power of up to 15 mW at 25°C. Also temperature and current tuning coefficients are comparable to those of DFB lasers. This paper will present an overview of laser concept, performance data and applications.

  16. Effect and clinical implications of the low-energy diode laser on bone cell proliferation.

    Science.gov (United States)

    Huertas, Rosa Medina; Luna-Bertos, Elvira De; Ramos-Torrecillas, Javier; Leyva, Francisco Medina; Ruiz, Concepción; García-Martínez, Olga

    2014-04-01

    Laser is a simple, noninvasive technique that has proven useful for treating damaged tissue. However, its effects on bone regeneration and the mechanisms involved are poorly understood. The objective of this study was to evaluate the effects on MG-63 cell proliferation of application of a pulsed diode laser (Ezlase) of 940 nm at low energy levels. After 24 hr of culture, osteoblasts underwent pulsed laser radiation at 0.5, 1, 1.5, and 2 W and fluences of 1-5 J. A control group was not irradiated. After the treatment, cells were incubated for 24 hr, and cell proliferation was analyzed using a spectrophotometric measure of cell respiration (MTT assay). Results were expressed as percentage proliferation versus controls. At 24-hr culture, cell proliferation was increased in laser-treated cells at intensities of 0.5, 1, and 1.5 W/cm(2) versus controls; the energy density was positively correlated with cell growth, which reached a peak at 3 J and decreased at higher fluences. The use of pulsed low-level laser with low-energy density range thus appears to exert a biostimulatory effect on bone tissue. Although the data on cell proliferation are robust, in-depth investigation is required into the effect of these irradiation doses on other cell parameters. The present findings demonstrate that laser therapy could be highly useful in tissue regeneration in different clinical settings, including nursing, physical therapy, dentistry, and traumatology.

  17. Diode laser-assisted transcanalicular dacryocystorhinostomy: the effect of age on the results

    Directory of Open Access Journals (Sweden)

    Fahrettin Akay

    2015-06-01

    Full Text Available ABSTRACT Purpose: The aim of this study was to explore the effect of age on the success of transcanalicular diode laser-assisted dacryocystorhinostomy (TCDCR. Methods: Seventy patients (70 eyes who underwent transcanalicular diode laser-assisted dacryocystorhinostomy for the treatment of nasolacrimal duct obstruction as a primary surgery were included in this retrospective, nonrandomized study. The patients were divided into two groups according to age. Mean ages were 21.3 ± 3.3 in group 1 and 60.3 ± 7.3 in group 2. The records of the 3-, 6-, and 12-month follow-up examinations were evaluated, and the anatomical and functional outcomes were noted. Functional success was defined as the absence of epiphora as indicated by the patient. Anatomical success was determined as patency of the neo-ostium with irrigation. Results: At the 3-month follow-up, 67% cases in group 1 showed anatomical success and 52% showed functional success; in group 2, the rates were 100% and 92%, respectively. Functional and anatomical success rates were the same for both the 6- and 12-month visits; 46% in group 1 and 76% in group 2. The results in group 2 were significantly better at all three follow-up visits (p<0.05. Conclusions: This study clearly showed that the older patients experienced better transcanalicular diode laser-assisted dacryocystorhinostomy results than the younger patients. The diminished inflammatory response in the older population may be a possible contributing factor to these results.

  18. Diode Laser Measurements of HF Concentrations from Heptane/Air Pan Fires Extinguished by FE-36 and FE-36 Plus Ammonium Polyphosphate

    National Research Council Canada - National Science Library

    Skaggs, R

    1999-01-01

    ... or FE-36 plus ammonium polyphosphate (APP). Recent advances in room temperature fiber coupled, near-infrared diode lasers provide isolation of the laser and signal processing electronics from the hostile sampling site...

  19. Advanced chip designs and novel cooling techniques for brightness scaling of industrial, high power diode laser bars

    Science.gov (United States)

    Heinemann, S.; McDougall, S. D.; Ryu, G.; Zhao, L.; Liu, X.; Holy, C.; Jiang, C.-L.; Modak, P.; Xiong, Y.; Vethake, T.; Strohmaier, S. G.; Schmidt, B.; Zimer, H.

    2018-02-01

    The advance of high power semiconductor diode laser technology is driven by the rapidly growing industrial laser market, with such high power solid state laser systems requiring ever more reliable diode sources with higher brightness and efficiency at lower cost. In this paper we report simulation and experimental data demonstrating most recent progress in high brightness semiconductor laser bars for industrial applications. The advancements are in three principle areas: vertical laser chip epitaxy design, lateral laser chip current injection control, and chip cooling technology. With such improvements, we demonstrate disk laser pump laser bars with output power over 250W with 60% efficiency at the operating current. Ion implantation was investigated for improved current confinement. Initial lifetime tests show excellent reliability. For direct diode applications 96% polarization are additional requirements. Double sided cooling deploying hard solder and optimized laser design enable single emitter performance also for high fill factor bars and allow further power scaling to more than 350W with 65% peak efficiency with less than 8 degrees slow axis divergence and high polarization.

  20. Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers.

    Science.gov (United States)

    Esteves-Oliveira, Marcella; de Guglielmi, Camila A B; Ramalho, Karen Müller; Arana-Chavez, Victor E; de Eduardo, Carlos Paula

    2010-09-01

    The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.