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Sample records for diode laser systems

  1. Compact diode array laser systems

    NASA Astrophysics Data System (ADS)

    Holtz, James Z.; Grove, Robert E.

    1995-04-01

    High pulse energy diode array laser systems have been constructed for therapeutic and diagnostic medical applications. Two systems are described. One system, constructed for therapeutic application in dermatology, uses 45 bars to generate > 10 joules of energy at approximately 800 nm in a 5-millisecond pulse. This system uses simple microlenses and non- imaging condensers to uniformly illuminate areas of 0.1 to 0.4 cm2 at fluences up to 40 joules per cm2. Cooling, power, and control electronics are housed within the control console, and the laser and condensing optics are housed in the handpiece connected to the control console by means of a two-meter umbilical. The complete system, including closed- cycle cooling, weighs under 14 kg and uses < 2 amps at 110 V. A second system, which is being developed as a burn diagnostic, utilizes a 15-bar diode laser array. The array generates over 3 joules of optical energy. The output light is homogenized and projected using microlenses, a non-imaging condenser, and projection optics. With this system an area of approximately 1000 cm2 can be uniformly illuminated at an intensity of one millijoule per square centimeter. The system, including receiving optics, can be battery-powered and packaged into a hand-held unit.

  2. Multipass matrix systems for diode laser spectroscope

    NASA Astrophysics Data System (ADS)

    Chernin, Semen M.

    1996-02-01

    Several modifications of multipass matrix systems (MMS) with a large relative aperture have been developed to be applied in diode laser spectroscopy. In these systems the images are formed on the field mirrors as compact rectangular matrices with a controlled amount of lines and columns. The number of passes may reach 600-1000 for mirrors with high-reflectivity layers (in three- and four-objective systems, respectively). In four-objective systems the error arising in the position of the previous odd image is compensated each time when images with even numbers are formed in the matrix. Moreover, four-objective systems provide the double superimposition of images in the matrix, resulting in a longer path length. Having a simple construction matrix systems ensure high optical and performance parameters. To improve performance characteristics of a matrix system operating under high vibration conditions (systems installed on aircraft or helicopter, etc.) a new promising variation of a four-objective matrix system was developed. Exit images of this modification are totally insensitive to vibrations. Matrix systems with a large angular aperture were developed for special applications with high resolution IR diode laser spectrometers. In view of their capacities, matrix systems are the new generation multipass systems.

  3. Header For Laser Diode

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  4. Wavelength stabilized multi-kW diode laser systems

    NASA Astrophysics Data System (ADS)

    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.

  5. Lighting with laser diodes

    NASA Astrophysics Data System (ADS)

    Basu, Chandrajit; Meinhardt-Wollweber, Merve; Roth, Bernhard

    2013-08-01

    Contemporary white light-emitting diodes (LEDs) are much more efficient than compact fluorescent lamps and hence are rapidly capturing the market for general illumination. LEDs are also replacing halogen lamps or even newer xenon based lamps in automotive headlamps. Because laser diodes are inherently much brighter and often more efficient than corresponding LEDs, there is great research interest in developing laser diode based illumination systems. Operating at higher current densities and with smaller form factors, laser diodes may outperform LEDs in the future. This article reviews the possibilities and challenges in the integration of visible laser diodes in future illumination systems.

  6. A Direct Diode Laser System Using a Planar Lightwave Circuit

    NASA Astrophysics Data System (ADS)

    Hasegawa, Kazuo; Matsubara, Hiroyuki; Ichikawa, Tadashi; Maeda, Mitsutoshi; Ito, Hiroshi

    2008-08-01

    In this paper we propose a direct diode laser (DDL) system consisting of laser diode (LD) bars, a planar lightwave circuit (PLC), and an optical fiber. We have developed a PLC as an optical power combiner and an LD mounting technology that is suitable for coupling to the PLC. A DDL system is presented that consists of six LD-PLC optical modules for the laser-welding of highly heat-resistant plastics. The total output power is in the 200 W class, with a spot diameter of 5.52 mm for the major axis and 5.00 mm for the minor axis at a focal length of 50 mm. The total output efficiency is 60.9% from the laser diode to the welding torch.

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

    NASA Astrophysics Data System (ADS)

    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. Battery-driven miniature LDA system with semiconductor laser diode

    NASA Astrophysics Data System (ADS)

    Damp, S.

    1988-06-01

    A one-component miniature system with dimensions of 11 by 4 by 4 cubic centimeters for laser-Doppler anemometry (LDA) is described. As power supply a 12V battery or any other source with the capability to drive a current up to 200mA can be used. The system contains the whole electronics to drive the used laser diode is a safe way. The electronics to amplify and buffer the LDA-signal which is received by a PIN-diode is included. The output of the system can directly fit a filterbank for example. Possible applications in rough environments are mentioned. Measurements show the reliability of the system.

  9. Direct laser diode welding system with anti-reflection unit

    NASA Astrophysics Data System (ADS)

    Nagayasu, Doukei; Wang, Jing-bo

    2003-11-01

    A high power laser diode system for welding is widely known. However, the reliability and the reasonability are required by an industrial market. Reliability, especially lifetime, mainly depends on the temperature of laser diode (LD) and it might be rise if LD would receive reflection from welding point. This paper conducted the measurement of the reflection during welding by applying 1/4 wavelength plate and PBS. Results indicated the reflection during welding was inevitable. We developed a prototype high power laser diode system, which equipped an anti-reflection unit, to improve the reliability. The system traveled 3m/min and its bead width was 1.2 mm for 1.5 mm Al (A5052) under the spot size 2.7 x 0.6 mm FWHM. Additionally, we started to develop fast and slow collimation lenses for LD to realize a reasonale price for system The brief evaluation of fast collimation lenses was also reported.

  10. 1047 nm laser diode master oscillator Nd:YLF power amplifier laser system

    NASA Technical Reports Server (NTRS)

    Yu, A. W.; Krainak, M. A.; Unger, G. L.

    1993-01-01

    A master oscillator power amplifier (MOPA) laser transmitter system at 1047 nm wavelength using a semiconductor laser diode and a diode pumped solid state (Nd:YLF) laser (DPSSL) amplifier is described. A small signal gain of 23 dB, a near diffraction limited beam, 1 Gbit/s modulation rates and greater than 0.6 W average power are achieved. This MOPA laser has the advantage of amplifying the modulation signal from the laser diode master oscillator (MO) with no signal degradation.

  11. 1047 nm laser diode master oscillator Nd:YLF power amplifier laser system

    NASA Technical Reports Server (NTRS)

    Yu, A. W.; Krainak, M. A.; Unger, G. L.

    1993-01-01

    A master oscillator power amplifier (MOPA) laser transmitter system at 1047 nm wavelength using a semiconductor laser diode and a diode pumped solid state (Nd:YLF) laser (DPSSL) amplifier is described. A small signal gain of 23 dB, a near diffraction limited beam, 1 Gbit/s modulation rates and greater than 0.6 W average power are achieved. This MOPA laser has the advantage of amplifying the modulation signal from the laser diode master oscillator (MO) with no signal degradation.

  12. Method and system for homogenizing diode laser pump arrays

    SciTech Connect

    Bayramian, Andrew James

    2016-05-03

    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%.

  13. Method and system for homogenizing diode laser pump arrays

    DOEpatents

    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%.

  14. [Tunable diode laser absorption spectroscopy system for trace ethylene detection].

    PubMed

    Pan, Wei-Dong; Zhang, Jia-Wei; Dai, Jing-Min; Song, Kai

    2012-10-01

    Tunable diode laser absorption spectroscopy (TDLAS) was characterized by ultra-narrow line width laser and wavelength modulation, which makes it possible to scan a single absorption line. TDLAS has an advantage in trace gas analysis for its high resolution, high sensitivity and quick response. The 1 626.8 nm absorption line of ethylene was selected for detecting by analyzing its absorption line characteristic. The TDLAS system was developed with a white type multi-pass cell, combined with wavelength modulation and harmonic detection. Ethylene concentration ranges from 20 to 1 200 ppmv were tested using this system. The estimated detection limit of the system is 10 ppmv.

  15. A simplified 461-nm laser system using blue laser diodes and a hollow cathode lamp for laser cooling of Sr

    PubMed Central

    Shimada, Yosuke; Chida, Yuko; Ohtsubo, Nozomi; Aoki, Takatoshi; Takeuchi, Makoto; Kuga, Takahiro; Torii, Yoshio

    2013-01-01

    We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks. PMID:23822327

  16. A simplified 461-nm laser system using blue laser diodes and a hollow cathode lamp for laser cooling of Sr.

    PubMed

    Shimada, Yosuke; Chida, Yuko; Ohtsubo, Nozomi; Aoki, Takatoshi; Takeuchi, Makoto; Kuga, Takahiro; Torii, Yoshio

    2013-06-01

    We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks.

  17. Off-line-locked laser diode species monitor system

    NASA Technical Reports Server (NTRS)

    Lee, Jamine (Inventor); Goldstein, Neil (Inventor); Richtsmeier, Steven (Inventor); Bien, Fritz (Inventor); Gersh, Michael (Inventor)

    1995-01-01

    An off-line-locked laser diode species monitor system includes: reference means for including at least one known species having a first absorption wavelength; a laser source for irradiating the reference means and at least one sample species having a second absorption wavelength differing from the first absorption wavelength by a predetermined amount; means for locking the wavelength of the laser source to the first wavelength of the at least one known species in the reference means; a controller for defeating the means for locking and for displacing the laser source wavelength from said first absorption wavelength by said predetermined amount to the second absorption wavelength; and a sample detector device for determining laser radiation absorption at the second wavelength transmitted through the sample to detect the presence of the at least one sample species.

  18. Superluminescent diode versus Fabry-Perot laser diode seeding in pulsed MOPA fiber laser systems for SBS suppression

    NASA Astrophysics Data System (ADS)

    Melo, M.; Sousa, J. M.; Salcedo, J. R.

    2015-03-01

    We demonstrate the use of a pulsed superluminescent diode (SLD) through direct current injection modulation as seeding source in a master oscillator power amplifier (MOPA) configuration when compared to a Fabry-Perot (FP) laser diode in the same system. The performance limitations imposed by the use of the Fabry-Perot lasers, caused by the backward high peak power pulses triggered due to stimulated Brillouin scattering (SBS) are not observed in the case of the SLD. Compared to conventional Fabry-Perot laser diodes, the SLD provides a smooth and broad output spectrum which is independent of the input pulse parameters. Moreover, the spectrum can be sliced and tailored to the application. Thus, free SBS operation is shown when using the SLD seeder in the same system, allowing for a significant increase on the extractable power and energy.

  19. Airborne tunable diode laser system for trace gas measurements

    NASA Technical Reports Server (NTRS)

    Sachse, G. W.; Hill, G. F.; Hoell, J. M., Jr.

    1983-01-01

    Sachse et al. (1976) have reported the development of an airborne tunable diode laser (TDL) system, named the Differential Absorption CO Monitor (DACOM). The absorption path was 10 m long and located in the free airstream along the fuselage of a C-54 aircraft. The present investigation is concerned with a modification of the DACOM instrument. Differences between the new instrument and the original one are related to a replacement of the external absorption path with a White cell. The instrument has the capability to suppress TDL excess noise. The laser refrigerator has been redesigned to permit an alternative method of cooling the TDL when electric power is not available.

  20. Tunable laser diode system for noninvasive blood glucose measurements

    NASA Astrophysics Data System (ADS)

    Olesberg, Jonathon T.; Arnold, Mark A.; Mermelstein, Carmen; Schmitz, Johannes; Wagner, Joachim

    2005-03-01

    Tight control of blood glucose levels has been shown to dramatically reduce the long-term complications of diabetes. Current invasive technology for monitoring glucose levels is effective but underutilized by people with diabetes because of the pain of repeated finger-sticks and the cost of reagent strips. Optical sensing of glucose could potentially allow more frequent monitoring and tighter glucose control for people with diabetes. The key to a successful optical non-invasive measurement of glucose is the collection of an optical spectrum with a very high signal-to-noise-ratio in a spectral region with significant glucose absorption. Unfortunately, the optical throughput of skin is very small due to absorption and scattering. To overcome these difficulties, we have developed a high-brightness tunable laser system for measurements in the 2.0-2.5 μm wavelength range. The system is based on a 2.3 micron wavelength, strained quantum-well laser diode incorporating GaInAsSb wells and AlGaAsSb barrier and cladding layers. Wavelength control is provided by coupling the laser diode to an external cavity that includes an acousto-optic tunable filter. Tuning ranges of greater than 110 nm have been obtained. Because the tunable filter has no moving parts, scans can be completed very quickly, typically in less than 10 ms. We describe the performance of the laser system and its potential for use in a non-invasive glucose sensor.

  1. A tunable diode laser absorption system for long path atmospheric transmission and high energy laser applications

    NASA Astrophysics Data System (ADS)

    Rice, Christopher A.; Perram, Glen

    2011-03-01

    An open-path Tunable Diode Laser Absorption Spectroscopy (TDLAS) system composed of narrow band (~300 kHz) diodes fiber coupled to a 12" Ritchey-Chrétien transmit telescope has been developed to study atmospheric transmission of key High Energy Laser wavelengths. The ruggedized system has been field deployed and tested for propagation distances of greater than 1 km. Initial experiments were performed in the vicinity of molecular oxygen X3Σ-g to b1Σ+gelectronic transition lines near 760 nm. The potassium version of the Diode Pumped Alkali Laser (DPAL) operates in between two of the sharp oxygen rotational features in the PP and the PQ branches. By scanning across many laser free spectral ranges and monitoring the laser frequency with a very precise wavemeter, the full structure of the oxygen molecular feature is observed. The device can also be used to observe rotational temperatures, oxygen concentrations, and total atmospheric pressure.

  2. Low-cost laser scanning photoacoustic microscopy system with a pulsed laser diode excitation source

    NASA Astrophysics Data System (ADS)

    Erfanzadeh, Mohsen; Zhu, Quing

    2017-03-01

    We present a low-cost laser scanning photoacoustic microscopy system with a pulsed laser diode as the excitation source. The system utilizes a 905 nm pulsed laser diode with 120 ns pulse width and 1 KHz repetition rate. No averaging is performed in data acquisition, resulting in a short image acquisition time. The maximum field of view is 4.6 mm × 3.7 mm and the lateral resolution is 71 μm. Images of human hairs and mouse ear are presented to demonstrate the feasibility of the system in imaging biological tissue.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Numerical simulations of a diode laser BPH treatment system

    NASA Astrophysics Data System (ADS)

    London, Richard A.; Esch, Victor C.; Papademetriou, Stephanos

    1999-06-01

    Numerical simulations are presented of the laser-tissue interaction of a diode laser system for treating benign prostate hyperplasia. The numerical model includes laser light transport, heat transport, cooling due to blood perfusion, thermal tissue damage, and enthalpy of tissue damage. Comparisons of the stimulation results to clinical data are given. We report that a reasonable variation from a standard set of input data produces heating times which match those measured in the clinical trials. A general trend of decreasing damage volume with increasing heating time is described. We suggest that the patient-to-patient variability seen in the data can be explained by differences in fundamental biophysical properties such as the optical coefficients. Further work is identified, including the measurement and input to the model of several specific data parameters such as optical coefficients, blood perfusion cooling rate, and coagulation rates.

  5. Numerical simulations of a diode laser BPH treatment system

    SciTech Connect

    Esch, V; London, R A; Papademetriou, S

    1999-02-23

    Numerical simulations are presented of the laser-tissue interaction of a diode laser system for treating benign prostate hyperplasia. The numerical model includes laser light transport, heat transport, cooling due to blood perfusion, thermal tissue damage, and enthalpy of tissue damage. Comparisons of the simulation results to clinical data are given. We report that a reasonable variation from a standard set of input data produces heating times which match those measured in the clinical trials. A general trend of decreasing damage volume with increasing heating time is described. We suggest that the patient-to- patient variability seen in the data can be explained by differences in fundamental biophysical properties such as the optical coefficients. Further work is identified, including the measurement and input to the model of several specific data parameters such as optical coefficients, blood perfusion cooling rate, and coagulation rates.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Diode-pumped laser with improved pumping system

    DOEpatents

    Chang, Jim J.

    2004-03-09

    A laser wherein pump radiation from laser diodes is delivered to a pump chamber and into the lasing medium by quasi-three-dimensional compound parabolic concentrator light channels. The light channels have reflective side walls with a curved surface and reflective end walls with a curved surface. A flow tube between the lasing medium and the light channel has a roughened surface.

  8. Fiber optic systems for diode-pumped solid state lasers

    NASA Astrophysics Data System (ADS)

    Kozlov, Valery A.; Awad, H. R. I.; Vlasenko, Oleg A.; Zavartsev, Yury D.; Zagumennyi, Alexander I.; Studenikin, Pavel A.; Shcherbakov, Ivan A.; Gordova, M. R.; Kuznetsov, A. V.

    1996-03-01

    Radial nonsymmetrical fiber endface microlenses original fabrication technique has been used for high efficient pump laser diode radiation coupling (up to 93% without AR coating) into the standard optical fibers and for the form of a pump power diagram at the output fiber endfaces. Nd:GdVO4 laser (2.5 mm crystals length) parameters with semiconfocal (output mirror curvature radius 10 cm) and monolith plane mirrors cavities have been measured for different pump diagrams formed by plane endfaces, spherical microlenses, and Selfoc lenses. Compact diode-pumped solid state lasers may be used in optical communications, optical storage, medicine, and other applications. Diode laser (DL)-optical fiber coupling gives several advantages for these pumping systems -- a possibility to combine several DLs radiation, a remote DLs mounting, small size and electrical safety of the laser heads, simple schemes of active crystals cooling, axial symmetry of the pumping beam for longitudinal geometry. In general, high coupling efficiency between a semiconductor light source and optical fiber may be achieved by the use of microlens, formed on the endface of the fiber. In this case bulk optical components between DL and optical fiber are not needed. In addition, the only reflection surface exists in this coupling technique. Different techniques for producing microlenses on a fiber endface have been developed. For example, tapered hemispherical lenses, melted, etched, and polished lenses are commonly used for this coupling. However, all types of such techniques produce in general radial symmetry lenses: therefore, they do not provide efficient coupling between a round fiber core and a nonsymmetrical DL's radiation. In this paper we demonstrate the fabrication technique of fiber endface radial nonsymmetrical microlenses with radii curvature from few micrometers to few tens micrometers by grinding/polishing process. This process may be used for producing different nonspherical microlenses

  9. Development of 100W class blue direct diode laser coating system for laser metal deposition

    NASA Astrophysics Data System (ADS)

    Higashino, R.; Tsukamoto, M.; Sato, Y.; Abe, N.; Asano, K.; Funada, Y.

    2017-02-01

    Laser cladding technique is widely used for industrial application such as oil, energy industry, and aircraft and so on because it is able to repair and to form a near net shape. This process have been employed infrared lasers with wavelength of 0.8-10.6μm since output power of these lasers have over 1000W. Metal processing efficiency was, however, low in these wavelength, because the absorption was low. Thus, we developed the laser cladding system with blue direct diode laser at the wavelength of 445nm. 6 blue diode lasers was combined on the focusing spot to reach the output power of 100W by a lens, which one blue diode laser module was maximum output power of 20W. By using this laser cladding system, a pure copper film coating on a SUS304 stainless steel plate was demonstrated from a copper powder. As the result, the copper layer was formed on SUS304 stainless steel plate at the width of 322μm and thickness of 534μm was formed on the substrate.

  10. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  11. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  12. Narrow bandwidth interference filter-stabilized diode laser systems for the manipulation of neutral atoms

    NASA Astrophysics Data System (ADS)

    Gilowski, M.; Schubert, Ch.; Zaiser, M.; Herr, W.; Wübbena, T.; Wendrich, T.; Müller, T.; Rasel, E. M.; Ertmer, W.

    2007-12-01

    We present and investigate different external cavity diode laser (ECDL) configurations for the manipulation of neutral atoms, wavelength-stabilized by a narrow-band high transmission interference filter. A novel diode laser, providing high output power of more than 1 W, with a linewidth of less than 85 kHz, based on a self-seeded tapered amplifier chip has been developed. Additionally, we compare the optical and spectral properties of two laser systems based on common laser diodes, differing in their coating, as well as one, based on a distributed-feedback (DFB) diode. The linear cavity setup in all these systems combines a robust and compact design with a high wavelength tunability and an improved stability of the optical feedback compared to diode laser setups using diffraction gratings for wavelength discrimination.

  13. A Heterodyne Interferometer For Testing Laser Diodes

    NASA Astrophysics Data System (ADS)

    1983-11-01

    A heterodyne, Mach-Zehnder interferometer system has been developed for testing the wavefront quality of laser diode collimator pens. The testing system is described and the problems associated with testing laser diodes are discussed.

  14. Velocimetry with diode lasers

    NASA Astrophysics Data System (ADS)

    de Mul, F. F. M.; Jentink, H. W.; Koelink, M.; Greve, J.; Aarnoudse, J. G.

    The history of the application of diode lasers in velocimetry is reviewed. Some problems arising when using those lasers, e.g., mode hopping and wavelength shifts caused by temperature effects, are discussed, together with coherence effects encountered with diode lasers. The application in dual-beam velocimetry, in direct-contact velocimetry and in velocimetry using self-mixing will be discussed.

  15. Etalon laser diode

    SciTech Connect

    Allen, L.B.; Koenig, H.G.; Rice, R.R.

    1981-08-18

    A laser diode is disclosed that is suitable for integrated and fiber optic applications requiring single transverse and single longitudinal mode operation. The single transverse mode is provided by making a gallium arsenide double heterostructural laser diode with a narrow stripe width and a relatively long length. The single longitudinal mode operation is provided by cracking the diode transverse to the stripe at one or more locations to form internal etalons in the laser cavity.

  16. Optical phase dynamics in mutually coupled diode laser systems exhibiting power synchronization

    NASA Astrophysics Data System (ADS)

    Pal, Vishwa; Prasad, Awadhesh; Ghosh, R.

    2011-12-01

    We probe the physical mechanism behind the known phenomenon of power synchronization of two diode lasers that are mutually coupled via their delayed optical fields. In a diode laser, the amplitude and the phase of the optical field are coupled by the so-called linewidth enhancement factor, α. In this work, we explore the role of optical phases of the electric fields in amplitude (and hence power) synchronization through α in such mutually delay-coupled diode laser systems. Our numerical results show that the synchronization of optical phases drives the powers of lasers to synchronized death regimes. We also find that as α varies for different diode lasers, the system goes through a sequence of in-phase amplitude-death states. Within the windows between successive amplitude-death regions, the cross-correlation between the field amplitudes exhibits a universal power-law behaviour with respect to α.

  17. NIR transmittance puse oximetry system with laser diodes

    NASA Astrophysics Data System (ADS)

    Lopez Silva, Sonnia M.; Silveira, Juan P.; Sendra, Jose R.; Giannetti, Romano; Dotor, Maria L.; Golmayo, Dolores

    2001-05-01

    A transmittance pulse oximetry system based on near-infrared laser diodes (LD) for monitoring arterial blood hemoglobin oxygen saturation (So2) has been previously reported. In this work we present the results obtained after improvements in the sensor configuration, signal processing algorithm and calibration procedure. The pulse oximetry system also comprises the sensor electronics, and a data acquisition board installed on a handheld personal computer. The two LD chips are mounted on a single metal heat-sink and as photo- detectors are used silicon p-i-n photodiodes with the first amplifier stage situated in their back side. The real time calculation of the parameters related to So2 is carried out through a numeric separation of the pulsatile and non- pulsatile components of the photoplethysmographic signals for both wavelengths and a non-linear filtering. Patients with respiratory failure conditions were monitored as a part of the calibration procedure in order to cover a wide range of So2-values. A calibration curve have been derived through the determination of in vitro arterial So2 with a significant quantity of experimental points ranging from 60 to almost 100%. The obtained results demonstrate that it is possible to apply the proposed system to monitoring a wide range of oxygen saturation levels.

  18. Diode Laser Arrays

    NASA Astrophysics Data System (ADS)

    Botez, Dan; Scifres, Don R.

    2005-11-01

    Contributors; 1. Monolithic phase-locked semiconductor laser arrays D. Botez; 2. High power coherent, semiconductor laser master oscillator power amplifiers and amplifier arrays D. F. Welch and D. G. Mehuys; 3. Microoptical components applied to incoherent and coherent laser arrays J. R. Leger; 4. Modeling of diode laser arrays G. R. Hadley; 5. Dynamics of coherent semiconductor laser arrays H. G. Winfuland and R. K. Defreez; 6. High average power semiconductor laser arrays and laser array packaging with an emphasis for pumping solid state lasers R. Solarz; 7. High power diode laser arrays and their reliability D. R. Scifres and H. H. Kung; 8. Strained layer quantum well heterostructure laser arrays J. J. Coleman; 9. Vertical cavity surface emitting laser arrays C. J. Chang-Hasnain; 10. Individually addressed arrays of diode lasers D. Carlin.

  19. AlGaInN laser diode technology for systems applications

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Gallium Nitride (GaN) laser diodes fabricated from the AlGaInN material system is an emerging technology that allows laser diodes to be fabricated over a very wide wavelength range from u.v. to the visible, and is a key enabler for the development of new system applications such as (underwater and terrestrial) telecommunications, quantum technologies, display sources and medical instrumentation.

  20. Reliability of high power diode laser systems based on single emitters

    NASA Astrophysics Data System (ADS)

    Leisher, Paul; Reynolds, Mitch; Brown, Aaron; Kennedy, Keith; Bao, Ling; Wang, Jun; Grimshaw, Mike; DeVito, Mark; Karlsen, Scott; Small, Jay; Ebert, Chris; Martinsen, Rob; Haden, Jim

    2011-03-01

    Diode laser modules based on arrays of single emitters offer a number of advantages over bar-based solutions including enhanced reliability, higher brightness, and lower cost per bright watt. This approach has enabled a rapid proliferation of commercially available high-brightness fiber-coupled diode laser modules. Incorporating ever-greater numbers of emitters within a single module offers a direct path for power scaling while simultaneously maintaining high brightness and minimizing overall cost. While reports of long lifetimes for single emitter diode laser technology are widespread, the complex relationship between the standalone chip reliability and package-induced failure modes, as well as the impact of built-in redundancy offered by multiple emitters, are not often discussed. In this work, we present our approach to the modeling of fiber-coupled laser systems based on single-emitter laser diodes.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Diode Pumped Fiber Laser

    DTIC Science & Technology

    1983-07-01

    d AFWU.-TR-83-niO 00 H CO CO iH <^ DIODE PUMPED FIBER LASER Edward L. Glnzton Laboratory Stanford University Stanford, California 94305...RECIPIf NT’S CATALOG NUMBER 4. TITLE Cand Sub(i(/e; DIODE PUMPED FIBER LASER 5 TYPE OF REPORT & PERIOD COVERED Interim Report...external optical cavity made of two miniature flat mirrors, and end- pumped either at 514.5 nm (argon-ion laser ) or near 818 nm ( laser diode ). Coherent

  3. Power-scalable system of phase-locked single-mode diode lasers.

    PubMed

    Bartelt-Berger, L; Brauch, U; Giesen, A; Huegel, H; Opower, H

    1999-09-20

    The direct use of diode lasers for high-power applications in material processing is limited to applications with relatively low beam quality and power density requirements. To achieve high beam quality one must use single-mode diode lasers, however with the drawback of relatively low optical output powers from these components. To realize a high-power system while conserving the high beam quality of the individual emitters requires coherent coupling of the emitters. Such a power-scalable system consisting of 19 slave lasers that are injection locked by one master laser has been built and investigated, with low-power diode lasers used for system demonstration. The optical power of the 19 injection-locked lasers is coupled into polarization-maintaining single-mode fibers and geometrically superimposed by a lens array and a focusing lens. The phase of each emitter is controlled by a simple electronic phase-control loop. The coherence of each slave laser is stabilized by computer control of the laser current and guarantees a stable degree of coherence of the whole system of 0.7. An enhancement factor of 13.2 in peak power density compared with that which was achievable with the incoherent superposition of the diode lasers was observed.

  4. Trace Detection with Diode Lasers

    NASA Astrophysics Data System (ADS)

    Fox, Richard W.

    1995-01-01

    Diode lasers were used to detect trace quantities of calcium, lead, chromium, cesium and rubidium. Extended -cavities were often employed for wavelength tuning and linewidth narrowing, and design considerations for the cavities are discussed. Calcium was detected under low pressure, Doppler-free conditions, and consequently the frequency stability of the laser's power spectrum was studied. The laser's frequency noise spectral density was measured and converted by calculation to the power spectrum. Examples of laser frequency noise densities with corresponding calculated power spectrums for free-running and frequency-locked conditions are given. An electronic feedback system to narrow a 657 nm wavelength diode laser's linewidth was constructed, and the resulting linewidth with respect to the locking cavity was measured to be approximately 500 Hz. Calcium atom concentrations of 0.35 x 10E-09 in water samples were measured by flame laser-enhanced ionization using a 423 nm wavelength frequency-doubled diode laser system. Analysis of the ionization signal and the noise was performed. Additional measurements of water samples with diode lasers demonstrated chromium detection at 25 x 10E-09, cesium at 0.25 x 10E -09, and rubidium at 0.25 x 10E-09. Lead was detected using a frequency-doubled diode system at a wavelength of 405 nm. The detection was by absorption from a metastable energy level; lead atoms in an argon vapor were excited into the metastable level by a radio-frequency discharge.

  5. Compact and smart laser diode systems for cancer treatment

    NASA Astrophysics Data System (ADS)

    Svirin, Viatcheslav N.; Sokolov, Victor V.; Solovieva, Tatiana I.

    2003-04-01

    To win the cancer is one of the most important mankind task to be decided in III Millenium. New technology of treatment is to recognize and kill cancer cells with the laser light not by surgery operation, but by soft painless therapy. Even though from the beginning of the 80s of the last century this technology, so-called photodynamic therapy (PDT) has received acceptance in America, Europe and Asia it is still considered in the medical circles to be a new method with the little-known approaches of cancer treatment. Recently the next step was done, and the unique method of PDT combined with laser-induced thermotherapy (LITT) was developed. Compact and smart diode laser apparatus "Modul-GF" for its realization was designed. In this report the concept of this method, experimental materials on clinical trials and ways of optimization of technical decisions and software of apparatus "Modul-GF", including the autotuning of laser power dependently on tissue temperature measured with thermosensors are discussed. The special instruments such as fiber cables and special sensors are described to permit application of "Modul-GF" for the treatment of the tumors of the different localizations, both surface and deeply located with using of the endoscopy method. The examples of the oncological and nononcological pathologies" treatment by the developed method and apparatus in urology, gynecology, gastroenterology, dermatology, cosmetology, bronchology, pulmonology are observed. The results of clinical approval the developed combination of PDT&LITT realized with "Modul-GF" leads to essentially increasing of the treatment effectiveness.

  6. Quantum dot diode lasers for optical communication systems

    SciTech Connect

    Zhukov, A E; Kovsh, A R

    2008-05-31

    Basic technological and physical aspects of injection lasers based on arrays of self-organised InAs/InGaAs quantum dots on GaAs substrates for optical communication systems in the 1.2-1.3 {mu}m spectral range are considered. The possibility of simultaneous lasing at a great number of longitudinal modes at a high power level and low noise is demonstrated. The use of these lasers in wavelength-division-multiplexing systems based on the spectral separation of the laser output spectrum is substantiated. (invited paper)

  7. Design of a kW-output fiber coupled diode laser system

    NASA Astrophysics Data System (ADS)

    Wu, Hualing; Guo, Linhui; Yu, Junhong; Gao, Songxin; Wu, Deyong

    2015-10-01

    Fiber-coupled diode laser pumping source is one of the key components of high-power fiber laser system. Its performance is significant to the output power of fiber laser system. A 1.8kW fiber-coupled diode laser system is designed by using ZEMAX optical design software. The technologies of high-precision beam collimation, spatial multiplexing, polarization multiplexing, beam expanding, focusing and coupling are used to couple the beams of 42 diode laser bars into a fiber with a core diameter of 200μm and NA 0.22. Every beam emit from diode laser bar is single polarization, and its central wavelength is 976nm @ 55W. The desigh result showed the fiber output power could reach 1800W, and the fiber-coupling efficiency was 78%, the brightness was 37MW/(cm2·sr),corresponding. This fiber-coupled system can be used in fiber pumping, material process and many other areas.

  8. Profile homogenization and monitoring for a multiple 100 J diode-laser pumping system

    NASA Astrophysics Data System (ADS)

    Siebold, M.; Podleska, S.; Hein, J.; Bödefeld, R.; Hornung, M.; Schnepp, M.; Sauerbrey, R.

    2005-09-01

    Multi-pass amplification to the 10 joule level for a femto-second CPA laser system is aimed at diode-pumping Yb3+ doped fluoride-phosphate glass with an energy of 240 J at 940 nm. Collimated pump light of 1000 laser diode bars is focussed onto an a circular glass disk with 28mm diameter. A two-sided ring shaped assembly of diode stacks and attached optics is applied for longitudinal pumping. We developed a computer aided optimization routine for positioning single pump foci with size of 4 × 8mm2 to achieve a smooth homogeneously distributed top-hat shaped pump profile with a diameter of 18 mm. For monitoring purpose the pulse energy of each diode stack is measured with a solar panel placed behind a reflecting mirror.

  9. Infrared diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Civiš, S.; Cihelka, J.; Matulková, I.

    2010-12-01

    Three types of lasers (double-heterostructure 66 K InAsSb/InAsSbP laser diode, room temperature, multi quantum wells with distributed feedback (MQW with DFB) (GaInAsSb/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs) (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) for the strongest absorption line of the v3 + v5 band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm-1 spectral range in case of InAsSb/InAsSbP laser (fundamental bands of v1, v5). Laser sensitive detection (laser absorption together with high resolution Fourier transform infrared technique including direct laser linewidth measurement, infrared photoacoustic detection of neutral molecules (methane, form-aldehyde) is discussed. Additionally, very sensitive laser absorption techniques of such velocity modulation are discussed for case of laser application in laboratory research of molecular ions. Such sensitive techniques (originally developed for lasers) contributed very much in identifying laboratory microwave spectra of a series of anions (C6H-, C4H-, C2H-, CN-) and their discovery in the interstellar space (C6H-, C4H-).

  10. Multi-diode laser system for UV exposure of the photoresists

    NASA Astrophysics Data System (ADS)

    Barbucha, R.; Tanski, M.; Kocik, M.

    2015-06-01

    PCB (Printed Circuit Board) industry is a global business for many years. PCB can be found in every electronic devices and since it becomes smaller, lighter and more efficient, new sophisticated machines need to be developed to meet this demands. The main parameter for the manufacturing machines is throughput. In this paper a multi-diode laser system for UV exposure of the photoresist on Printed Circuit Board is presented. The multi-diode laser system presents high throughput at high resolution of the pattern as well as low development costs.

  11. Diode laser satellite systems for beamed power transmission

    NASA Technical Reports Server (NTRS)

    Williams, M. D.; Kwon, J. H.; Walker, G. H.; Humes, D. H.

    1990-01-01

    A power system composed of an orbiting laser satellite and a surface-based receiver/converter is described. Power is transmitted from the satellite to the receiver/converter by laser beam. The satellite components are: (1) solar collector; (2) blackbody; (3) photovoltaic cells; (4) heat radiators; (5) laser system; and (6) transmission optics. The receiver/converter components are: receiver dish; lenticular lens; photocells; and heat radiator. Although the system can be adapted to missions at many locations in the solar system, only two are examined here: powering a lunar habitat; and powering a lunar rover. Power system components are described and their masses, dimensions, operating powers, and temperatures, are estimated using known or feasible component capabilities. The critical technologies involved are discussed and other potential missions are mentioned.

  12. Blue-green diode-pumped solid state laser system for transcutaneous bilirubinometry in neonatal jaundice

    NASA Astrophysics Data System (ADS)

    Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

    2001-01-01

    The authors introduce the design of a blue-green diode- pumped solid-state laser system for transcutaneous measurement of serum bilirubin level in jaundiced new born infant. The system follows the principles of optical bilirubinometry. The choice of wavelengths provides correction for the presence of hemoglobin. The new design is more compact and less expensive.

  13. A commercial tunable diode laser (TDL) system for on-line remote measurements of automobile emissions

    NASA Astrophysics Data System (ADS)

    Weber, Konradin; Ropertz, Alexander; Schwabe, Thomas; Fischer, Christian; van Haren, Gunther

    2004-11-01

    An innovative tunable diode laser (TDL) measurement system has been used for the on-line estimation of emissions of cars, driving through the measurement beam of the system. This paper describes the measurement principle and gives first measurement results, taken for different types of cars.

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

    PubMed

    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.

  15. A simple readout electronics for automatic power controlled self-mixing laser diode systems.

    PubMed

    Cattini, Stefano; Rovati, Luigi

    2008-08-01

    The paper describes a simple electronic circuit to drive a laser diode for self-mixing interferometry. The network integrates a stable commercial automatic power controller and a current mirror based readout of the interferometric signal. The first prototype version of the circuit has been realized and characterized. The system allows easily performing precise interferometric measurements with no thermostatic circuitry to stabilize the laser diode temperature and an automatic control gain network to compensate emitted optical power fluctuations. To achieve this result, in the paper a specific calibration procedure to be performed is described.

  16. 1 W CW diode-pumped Nd:YAG laser for coherent space communication systems

    NASA Astrophysics Data System (ADS)

    Johann, U.; Seelert, W.

    1991-05-01

    A design concept suitable for space applications is proposed on the basis of a diode-pumped Nd:YAG laser transmitter laboratory breadboard; this transmitter must not only furnish the data carrier but also serve as a tracking reference and (in conjunction with a boost amplifier) as a beacon for receiver-station acquisition. The diffraction-limited beam is generated with 6.3-percent electrical-to-optical conversion efficiency. The proposed space communications system will incorporate astigmatically-focused stacked-laser diodes for continuous reliable operation over the course of seven years.

  17. Fibre-coupled air-cooled high-power diode laser systems

    NASA Astrophysics Data System (ADS)

    Bartoschewski, Daniel; Meinschien, Jens; Fornahl, Udo

    2008-02-01

    Current laser systems based on high-power laser diode bars need active cooling either water cooling or the use of thermo-electric coolers to ensure an adequate operating temperature for a reasonable lifetime. Here is a solution with a bonded fin heat sink and forced ventilation introduced, a diode laser bar with an improved efficiency and a low thermal resistance as well as an optical system for a highly efficient fibre coupling. With this system it is possible to couple 25 Watt continuous wave power from a single laser diode bar on a passive heat sink into a fibre with 200 μm core diameter. The basis for this performance is a heat sink with an exceptionally low thermal resistance. Several new features are introduced to reach a low overall gradient between the laser diode temperature and the ambient temperature. In addition, it does geometrically fit to the layout of the optical design. Shape and aspect ratio of both heat sink and housing of the laser system are matched to each other. Another feature is the use of hard-soldered or pressed bars to achieve a thermo-mechanically stable performance. The long-term thermal characteristic was tested. The operation temperature comes to saturation after about 30 minutes. Therefore it can be used for continuous wave operation at 25 Watt output power. At a quasi continuous operation at 70 percent duty cycle a peak power of 30 Watt out of the fibre is possible. From this technology results a compact fibre coupled laser system what is simple to drive compared with current high power laser systems, because there is no need to control the operating temperature. This gives way for more compact driver solutions. Fields of application are laser marking systems and material processing, where a simple driver system is requested. Also medical applications need this requirement and a compact cooling too so that mobile integrated solutions become possible. Further developments allow multiple laser diode systems for specific industrial

  18. Design and characterization of a novel power over fiber system integrating a high power diode laser

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  19. Schlieren with a laser diode source

    NASA Astrophysics Data System (ADS)

    Burner, A. W.; Franke, J. M.

    1981-10-01

    The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.

  20. Long-term frequency stabilization system for external cavity diode laser based on mode boundary detection.

    PubMed

    Xu, Zhouxiang; Huang, Kaikai; Jiang, Yunfeng; Lu, Xuanhui

    2011-12-01

    We have realized a long-term frequency stabilization system for external cavity diode laser (ECDL) based on mode boundary detection method. In this system, the saturated absorption spectroscopy was used. The current and the grating of the ECDL were controlled by a computer-based feedback control system. By checking if there are mode boundaries in the spectrum, the control system determined how to adjust current to avoid mode hopping. This procedure was executed periodically to ensure the long-term stabilization of ECDL in the absence of mode hops. This diode laser system with non-antireflection coating had operated in the condition of long-term mode-hop-free stabilization for almost 400 h, which is a significant improvement of ECDL frequency stabilization system.

  1. Long-term frequency stabilization system for external cavity diode laser based on mode boundary detection

    NASA Astrophysics Data System (ADS)

    Xu, Zhouxiang; Huang, Kaikai; Jiang, Yunfeng; Lu, Xuanhui

    2011-12-01

    We have realized a long-term frequency stabilization system for external cavity diode laser (ECDL) based on mode boundary detection method. In this system, the saturated absorption spectroscopy was used. The current and the grating of the ECDL were controlled by a computer-based feedback control system. By checking if there are mode boundaries in the spectrum, the control system determined how to adjust current to avoid mode hopping. This procedure was executed periodically to ensure the long-term stabilization of ECDL in the absence of mode hops. This diode laser system with non-antireflection coating had operated in the condition of long-term mode-hop-free stabilization for almost 400 h, which is a significant improvement of ECDL frequency stabilization system.

  2. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    NASA Astrophysics Data System (ADS)

    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.

  3. Optoacoustic system based on 808-nm high energy short pulse diode laser stacks

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    In the last few decades, high power diode lasers (HPDL) have been introduced as alternative laser sources for optoacoustic imaging (OAI), due to their high repetition rates (a few kHz) for fast OA image acquisition, lower cost and size if compared to solid state lasers. Nevertheless, their drawbacks consist in a low energy per pulse (μJ) and a relatively highly divergent beam that needs collimation optics. At this purpose, the employment of diode laser stacks significantly increases the energy per pulse up to several mJ. The diode laser stacks imply a big challenge if compared to single emitters for several reasons. Firstly, they need very demanding electronic requirements, as forward voltages and currents of several tens of volts and hundreds of amperes, respectively. Secondly, their highly divergent beam profile requires precise collimation by means of fast axis and slow axis collimation. In this work, we show an 808-nm diode laser stack driven with 17 V and 200 A by a low-cost current driver for emitting pulses of 1 mJ at 1 kHz. Particular emphasis will be attributed to the design of the high current pulses driver and the optics employed to collimate and after focus the beam in a spot. The light spot will be applied to an ink inclusion hosted in turbid phantom. We demonstrate that our system is able to generate appreciable OA signals in turbid phantoms. This aspect represents a novelty in OAI systems because it is demonstrated that HPDL sources can efficiently replace solid-state lasers.

  4. A compact and robust diode laser system for atom interferometry on a sounding rocket

    NASA Astrophysics Data System (ADS)

    Schkolnik, V.; Hellmig, O.; Wenzlawski, A.; Grosse, J.; Kohfeldt, A.; Döringshoff, K.; Wicht, A.; Windpassinger, P.; Sengstock, K.; Braxmaier, C.; Krutzik, M.; Peters, A.

    2016-08-01

    We present a diode laser system optimized for laser cooling and atom interferometry with ultra-cold rubidium atoms aboard sounding rockets as an important milestone toward space-borne quantum sensors. Design, assembly and qualification of the system, combing micro-integrated distributed feedback (DFB) diode laser modules and free space optical bench technology, is presented in the context of the MAIUS (Matter-wave Interferometry in Microgravity) mission. This laser system, with a volume of 21 l and total mass of 27 kg, passed all qualification tests for operation on sounding rockets and is currently used in the integrated MAIUS flight system producing Bose-Einstein condensates and performing atom interferometry based on Bragg diffraction. The MAIUS payload is being prepared for launch in fall 2016. We further report on a reference laser system, comprising a rubidium stabilized DFB laser, which was operated successfully on the TEXUS 51 mission in April 2015. The system demonstrated a high level of technological maturity by remaining frequency stabilized throughout the mission including the rocket's boost phase.

  5. High speed photoacoustic tomography system with low cost portable pulsed diode laser

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Sivasubramanian, Kathyayini; Pramanik, Manojit

    2015-07-01

    Photoacoustic tomography (PAT) is a potential hybrid imaging modality that has attracted great attention in the fields of medical imaging. In order to generate photoacoustic signal efficiently Q-switched Nd:YAG pump lasers capable of generating tens of millijoules of nanosecond laser pulses have been widely used. However, PAT systems using such lasers have limitations in clinical applications because of their high cost, large size, and cooling requirements. Furthermore, the low pulse repetition rate (PRR) of tens of hertz is not suitable for real-time PAT. So, there is a need for inexpensive, compact, simple, fast imaging system for clinical applications. Nanosecond pulsed laser diodes could meet these requirements. In this work, we present a high-speed photoacoustic tomography imaging system that uses a compact and yet relatively powerful near-infrared pulsed laser diode. The PAT system was tested on phantoms to verify its potential imaging speed. Photoacoustic reconstructed images at different scanning speeds are presented. With single ultrasound detector scanning, the system could provide PA image ~10 times faster than the Nd:YAG laser based systems.

  6. A low-cost photoacoustic microscopy system with a laser diode excitation

    PubMed Central

    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

  7. Properties and Frequency Conversion of High-Brightness Diode-Laser Systems

    NASA Astrophysics Data System (ADS)

    Boller, Klaus-Jochen; Beier, Bernard; Wallenstein, Richard

    An overview of recent developments in the field of high-power, high-brightness diode-lasers, and the optically nonlinear conversion of their output into other wavelength ranges, is given. We describe the generation of continuous-wave (CW) laser beams at power levels of several hundreds of milliwatts to several watts with near-perfect spatial and spectral properties using Master-Oscillator Power-Amplifier (MOPA) systems. With single- or double-stage systems, using amplifiers of tapered or rectangular geometry, up to 2.85 W high-brightness radiation is generated at wavelengths around 810nm with AlGaAs diodes. Even higher powers, up to 5.2W of single-frequency and high spatial quality beams at 925nm, are obtained with InGaAs diodes. We describe the basic properties of the oscillators and amplifiers used. A strict proof-of-quality for the diode radiation is provided by direct and efficient nonlinear optical conversion of the diode MOPA output into other wavelength ranges. We review recent experiments with the highest power levels obtained so far by direct frequency doubling of diode radiation. In these experiments, 100mW single-frequency ultraviolet light at 403nm was generated, as well as 1W of single-frequency blue radiation at 465nm. Nonlinear conversion of diode radiation into widely tunable infrared radiation has recently yielded record values. We review the efficient generation of widely tunable single-frequency radiation in the infrared with diode-pumped Optical Parametric Oscillators (OPOs). With this system, single-frequency output radiation with powers of more than 0.5W was generated, widely tunable around wavelengths of 2.1,m and 1.65,m and with excellent spectral and spatial quality. These developments are clear indicators of recent advances in the field of high-brightness diode-MOPA systems, and may emphasize their future central importance for applications within a vast range of optical

  8. Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

    PubMed Central

    BRIANEZZI, Leticia Ferreira de Freitas; MAENOSONO, Rafael Massunari; BIM, Odair; ZABEU, Giovanna Speranza; PALMA-DIBB, Regina Guenka; ISHIKIRIAMA, Sérgio Kiyoshi

    2017-01-01

    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 (p<0.05): SB>SU. 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. PMID:28877276

  9. Nonlinear distortion evaluation in a directly modulated distributed feedback laser diode-based fiber-optic cable television transport system

    NASA Astrophysics Data System (ADS)

    Li, Chung-Yi; Ying, Cheng-Ling; Lin, Chun-Yu; Chu, Chien-An

    2015-12-01

    This study evaluated a directly modulated distributed feedback (DFB) laser diode (LD) for cable TV systems with respect to carrier-to-nonlinear distortion of LDs. The second-order distortion-to-carrier ratio is found to be proportional to that of the second-order coefficient-to-first-order coefficient of the DFB laser diode driving current and to the optical modulation index (OMI). Furthermore, the third-order distortion-to-carrier ratio is proportional to that of the third-order coefficient-to-first-order coefficient of the DFB laser diode driving current, and to the OMI2.

  10. Compact deep UV laser system at 222.5 nm by single-pass frequency doubling of high-power GaN diode laser emission

    NASA Astrophysics Data System (ADS)

    Ruhnke, Norman; Müller, André; Eppich, Bernd; Güther, Reiner; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2016-03-01

    Deep ultraviolet (DUV) lasers emitting below 300 nm are of great interest for many applications, for instance in medical diagnostics or for detecting biological agents. Established DUV lasers, e.g. gas lasers or frequency quadrupled solid-state lasers, are relatively bulky and have high power consumptions. A compact and reliable laser diode based system emitting in the DUV could help to address applications in environments where a portable and robust light source with low power consumption is needed. In this work, a compact DUV laser system based on single-pass frequency doubling of highpower GaN diode laser emission is presented. A commercially available high-power GaN laser diode from OSRAM Opto Semiconductors serves as a pump source. The laser diode is spectrally stabilized in an external cavity diode laser (ECDL) setup in Littrow configuration. The ECDL system reaches a maximum optical output power of 700 mW, maintaining narrowband emission below 60 pm (FWHM) at 445 nm over the entire operating range. By direct single pass frequency doubling in a BBO crystal with a length of 7.5 mm a maximum DUV output power of 16 μW at a wavelength of 222.5 nm is generated. The presented concept enables compact and efficient diode laser based light sources emitting in the DUV spectral range that are potentially suitable for in situ applications where a small footprint and low power consumption is essential.

  11. Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

    PubMed

    Brianezzi, Leticia Ferreira de Freitas; Maenosono, Rafael Massunari; Bim, Odair; Zabeu, Giovanna Speranza; Palma-Dibb, Regina Guenka; Ishikiriama, Sérgio Kiyoshi

    2017-01-01

    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. 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). 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 (p<0.05): SB>SU. 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.

  12. [Signal analysis and spectrum distortion correction for tunable diode laser absorption spectroscopy system].

    PubMed

    Bao, Wei-Yi; Zhu, Yong; Chen, Jun; Chen, Jun-Qing; Liang, Bo

    2011-04-01

    In the present paper, the signal of a tunable diode laser absorption spectroscopy (TDLAS) trace gas sensing system, which has a wavelength modulation with a wide range of modulation amplitudes, is studied based on Fourier analysis method. Theory explanation of spectrum distortion induced by laser intensity amplitude modulation is given. In order to rectify the spectrum distortion, a method of synchronous amplitude modulation suppression by a variable optical attenuator is proposed. To validate the method, an experimental setup is designed. Absorption spectrum measurement experiments on CO2 gas were carried out. The results show that the residual laser intensity modulation amplitude of the experimental system is reduced to -0.1% of its original value and the spectrum distortion improvement is 92% with the synchronous amplitude modulation suppression. The modulation amplitude of laser intensity can be effectively reduced and the spectrum distortion can be well corrected by using the given correction method and system. By using a variable optical attenuator in the TDLAS (tunable diode laser absorption spectroscopy) system, the dynamic range requirements of photoelectric detector, digital to analog converter, filters and other aspects of the TDLAS system are reduced. This spectrum distortion correction method can be used for online trace gas analyzing in process industry.

  13. Controlling Fringe Sensitivity of Electro-Optic Holography Systems Using Laser Diode Current Modulation

    NASA Technical Reports Server (NTRS)

    Bybee, Shannon J.

    2001-01-01

    Electro-Optic Holography (EOH) is a non-intrusive, laser-based, displacement measurement technique capable of static and dynamic displacement measurements. EOH is an optical interference technique in which fringe patterns that represent displacement contour maps are generated. At excessively large displacements the fringe density may be so great that individual fringes are not resolvable using typical EOH techniques. This thesis focuses on the development and implementation of a method for controlling the sensitivity of the EOH system. This method is known as Frequency Translated Electro-Optic Holography (FTEOH). It was determined that by modulating the current source of the laser diode at integer multiples of the object vibration, the fringe pattern is governed by higher order Bessel function of the first kind and the number of fringes that represent a given displacement can be controlled. The reduction of fringes is theoretically unlimited but physically limited by the frequency bandwidth of the signal generator, providing modulation to the laser diode. Although this research technique has been verified theoretically and experimentally in this thesis, due to the current laser diode capabilities it is a tedious and time consuming process to acquire data using the FTEOH technique.

  14. Laser diode initiated detonators for space applications

    NASA Technical Reports Server (NTRS)

    Ewick, David W.; Graham, J. A.; Hawley, J. D.

    1993-01-01

    Ensign Bickford Aerospace Company (EBAC) has over ten years of experience in the design and development of laser ordnance systems. Recent efforts have focused on the development of laser diode ordnance systems for space applications. Because the laser initiated detonators contain only insensitive secondary explosives, a high degree of system safety is achieved. Typical performance characteristics of a laser diode initiated detonator are described in this paper, including all-fire level, function time, and output. A finite difference model used at EBAC to predict detonator performance, is described and calculated results are compared to experimental data. Finally, the use of statistically designed experiments to evaluate performance of laser initiated detonators is discussed.

  15. Diode laser (980nm) cartilage reshaping

    NASA Astrophysics Data System (ADS)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  16. Materials Systems for 2- to 5-Micrometers Wavelength Diode Lasers

    DTIC Science & Technology

    1990-08-22

    for the Department of the Air Force under Contract F19628.90.C.0002. Approved for public release; distribution is unlimited This report is based on...Department of the Air Force under Contract F19628-90-C-0002. This report ma be reproduced to satisfy needs of U.S. Government agencies. The ESD Public...energy band vs distance for a strained-layer MQW laser. Discrete levels in the wells are not shown. Occupied states under forward-bias conditions are

  17. Qualification and Selection of Flight Diode Lasers for Space Applications

    NASA Technical Reports Server (NTRS)

    Liebe, Carl C.; Dillon, Robert P.; Gontijo, Ivair; Forouhar, Siamak; Shapiro, Andrew A.; Cooper, Mark S.; Meras, Patrick L.

    2010-01-01

    The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode

  18. Multi-wavelength photoacoustic system based on high-power diode laser bars

    NASA Astrophysics Data System (ADS)

    Leggio, Luca; Wiśniowski, Bartosz; Gawali, Sandeep Babu; Rodríguez, Sergio; Sánchez, Miguel; Gallego, Daniel; Carpintero, Guillermo; Lamela, Horacio

    2017-03-01

    Multi-wavelength laser sources are necessary for a functional photoacoustic (PA) spectroscopy. The use of high-power diode lasers (HPDLs) has aroused great interest for their relatively low costs and small sizes if compared to solid state lasers. However, HPDLs are only available at few wavelengths and can deliver low optical energy (normally in the order of μJ), while diode laser bars (DLBs) offer more wavelengths in the market and can deliver more optical energy. We show the simulations of optical systems for beam coupling of single high-power DLBs operating at different wavelengths (i.e. 808 nm, 880 nm, 910 nm, 940 nm, and 980 nm) into 400-μm optical fibers. Then, in a separate design, the beams of the DLBs are combined in a compact system making use of dichroic mirrors and focusing lenses for beam coupling into a 400-μm optical fiber. The use of optical fibers with small core diameter (< 1 mm) is particularly suggestive for future photoacoustic endoscopy (PAE) applications that require interior examination of the body.

  19. 11-kW direct diode laser system with homogenized 55 × 20 mm2 Top-Hat intensity distribution

    NASA Astrophysics Data System (ADS)

    Köhler, Bernd; Noeske, Axel; Kindervater, Tobias; Wessollek, Armin; Brand, Thomas; Biesenbach, Jens

    2007-02-01

    In comparison with other laser systems diode lasers are characterized by a unique overall efficiency, a small footprint and high reliability. However, one major drawback of direct diode laser systems is the inhomogeneous intensity distribution in the far field. Furthermore the output power of current commercially available systems is limited to about 6 kW. We report on a diode laser system with 11 kW output power at a single wavelength of 940 nm aiming for customer specific large area treatment. To the best of our knowledge this is the highest output power reported so far for a direct diode laser system. In addition to the high output power the intensity distribution of the laser beam is homogenized in both axes leading to a 55 x 20 mm2 Top-Hat intensity profile at a working distance of 400 mm. Homogeneity of the intensity distribution is better than 90%. The intensity in the focal plane is 1 kW/cm2. We will present a detailed characterization of the laser system, including measurements of power, power stability and intensity distribution of the homogenized laser beam. In addition we will compare the experimental data with the results of non-sequential raytracing simulations.

  20. Advanced laser diodes for sensing applications

    SciTech Connect

    VAWTER,GREGORY A.; MAR,ALAN; CHOW,WENG W.; ALLERMAN,ANDREW A.

    2000-01-01

    The authors have developed diode lasers for short pulse duration and high peak pulse power in the 0.01--100.0 m pulsewidth regime. A primary goal of the program was producing up to 10 W while maintaining good far-field beam quality and ease of manufacturability for low cost. High peak power, 17 W, picosecond pulses have been achieved by gain switching of flared geometry waveguide lasers and amplifiers. Such high powers area world record for this type of diode laser. The light emission pattern from diode lasers is of critical importance for sensing systems such as range finding and chemical detection. They have developed a new integrated optical beam transformer producing rib-waveguide diode lasers with a symmetric, low divergence, output beam and increased upper power limits for irreversible facet damage.

  1. Laser Diode Pumped Solid State Lasers

    DTIC Science & Technology

    1987-01-01

    structures, monolithic phased arrays, multiple stripe lasers which were made possible by improved manufacturing technologies su LPE and particular...mass production of single laser diodes in Japan, went a development in the U.S. which is aimed at the fabrication of powerful monolithic arrays. The...Significant progress has been made recently in developing the monolithic , linear laser diode array. Output power, slope efficiency, laser threshold and

  2. Laterally injected light-emitting diode and laser diode

    SciTech Connect

    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.

  3. A compact diode laser based all-fiber delivery system for PDT+PTT with integrated temperature sensing capabilities

    NASA Astrophysics Data System (ADS)

    Gassino, Riccardo; Kokalari, Ida; Vallan, Alberto; Fenoglio, Ivana; Perrone, Guido

    2017-02-01

    The paper first reviews the main laser based cancer therapies and then presents a new 9xx nm high power laser diode system specifically devised to irradiate carbon graphitic nanoparticles that have shown photodynamic and photo-thermal behavior when exposed to near-IR laser light. The peculiarity of the laser system is that its delivery is through a fiber probe that integrates Bragg gratings to allow monitoring the induced temperature increase without introducing artifacts due to the interaction with the laser beam. Experimental validations through EPR spectrum and temperature measurements on hydroxylated fullerene and carbon nanoparticle samples are provided to assess the effectiveness of the developed system.

  4. A clinical study of failure in microchannel cooled diodes used in large laser systems

    NASA Astrophysics Data System (ADS)

    Jackel, Steven; Meir, Avi; Horvitz, Zvi; Moshe, Inon; Shimoni, Yehoshua; Lumer, Yaakov; Feldman, Revital; Hershko, Izhak; Pekin, Yotam

    2011-04-01

    In this paper we investigate the source of failure in commercial, microchannel cooled CW diode bars placed in 12 bar horizontal arrays. The arrays were used to pump Nd:YAG rods in our 10 kW developmental laser. The laser was operated at low duty factor over a period of over 2 years. Experimental evidence indicated that the sudden, catastrophic failure was because of degraded cooling. We used optical microscopes, an X-ray microfocus imager, and a thermal neutron scattering camera to look inside the microcoolers. Our investigations revealed only one possible failure mechanism: cooling flow reduction because of delamination of the Au coating the walls of the microcoolers and the entrapment of Au flakes within the microchannel structures. We observed blisters in the microcoolers under working bars, and flake-like structures in the microcoolers under burnt-out bars (all taken from the laser). We observed no evidence of either massive blockages because of electrochemical deposits, or of corrosion/erosion in the microchannel walls. Integral operation times of the high flow-rate cooling system and of the diodes themselves were too short by one and two orders of magnitude, respectively, to explain the observed failures. Microchannel immersion times in the deionized water were, however, long enough to allow for corrosion of metals that may have been exposed through defects in the Au coatings. Three-dimensional heat flow simulations showed that blockage of multiple microchannels towards the edge of a bar can easily lead to catastrophic temperature increases.

  5. Highly modular high-brightness diode laser system design for a wide application range

    NASA Astrophysics Data System (ADS)

    Fritsche, Haro; Kruschke, Bastian; Koch, Ralf; Ferrario, Fabio; Kern, Holger; Pahl, Ullrich; Ehm, Einar; Pflueger, Silke; Grohe, Andreas; Gries, Wolfgang

    2015-03-01

    For an economic production it is important to serve as many applications as possible while keeping the product variations minimal. We present our modular laser design, which 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. Those 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 100W with BPP of <3.5 mm*mrad (FA) and <5 mm*mrad (SA). Further power scaling is accomplished by polarization and wavelength multiplexing yielding high optical efficiencies of more than 80% and results in about 500 W launched into a 100 μm fiber with 0.15 NA. Subsequently those building blocks can be stacked also by the very same dense spectral combing technique up to multi kW Systems without further reduction of the BPP. These "500W building blocks" are consequently designed in a way that without any system change new wavelengths can be implemented by only exchanging parts but without change of the production process. This design principal offers the option to adapt the wavelength of those blocks to any applications, from UV, visible into the far IR. From laser pumping and scientific applications to materials processing such as cutting and welding of copper aluminum or steel and also medical application. 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 pumping of Erbium lasers.[1] Furthermore, the fully integrated electronic concept allows addressing further applications, as it is capable of very short μs pulses up to cw mode operation by simple software commands.

  6. High power diode pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.

    2008-05-01

    Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

  7. Coordinate interferometric system for measuring the position of a sample with infrared telecom laser diode

    NASA Astrophysics Data System (ADS)

    Holá, Miroslava; Lazar, Josef; Čížek, Martin; Hucl, Václav; Řeřucha, Šimon; Číp, Ondřej

    2016-11-01

    We report on a design of an interferometric position measuring system for control of a sample stage in an e-beam writer with reproducibility of the position on nanometer level and resolution below nanometer. We introduced differential configuration of the interferometer where the position is measured with respect to a central reference point to eliminate deformations caused by thermal and pressure effects on the vacuum chamber. The reference is here the electron gun of the writer. The interferometer is designed to operate at infrared, telecommunication wavelength due to the risk of interference of stray light with sensitive photodetectors in the chamber. The laser source is here a narrow-linewidth DFB laser diode with electronics of our own design offering precision and stability of temperature and current, low-noise, protection from rf interference, and high-frequency modulation. Detection of the interferometric signal relies on a novel derivative technique utilizing hf frequency modulation and phase-sensitive detection.

  8. Tissue welding with 980-nm diode laser system: preliminary study for determination of optimal parameters

    NASA Astrophysics Data System (ADS)

    Korkut, Zeynep D.; Tabakoglu, Haşim Ö.; Bozkulak, Özgüncem; Aksel, Ayla A.; Gulsoy, Murat

    2006-02-01

    In this study, tissue welding with 980-nm laser system, which is first-time in the literature, was performed. Hence, a preliminary study was done to determine optimal parameters for further studies. 1 cm long incisions done on the Wistar rat's dorsal skin were welded. Tissue welding with 980-nm wavelength depends on the degree of photothermal interaction. Thus, different power levels and exposure schedule were investigated. Dorsal sides of all animals were photographed from the date of surgery until they were sacrificed. The clinical examination - opening of wound and presence of infection - was noted. The rats did not show any abnormality on their health, behavior and nutrition manner. As a result, 980-nm diode laser was concluded to be a good candidate for tissue welding applications.

  9. Design of a novel pulsed laser diode induced photoacoustic imaging system for tumor diagnosis

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Zeng, Lvming; Liu, Guodong; Huang, Zhen

    2012-03-01

    The tumors are one of most dangerous diseases in lots of diseases Expect for the actively treating of antitumor, the early detection of tumors is a key important step in the course of tumor treatment. Since some drawbacks existed in the traditional methods of tumor detection, such as ultrasound imaging, X radiography, CT imaging, OCT and MRI, etc, a novel hybrid and promising imaging method, that is, photoacoustic imaging (PAI) technology, is used to the tumors diagnosis(TD) in this work. This novel method has higher resolution, contrast and penetration depth due to the merits combination of ultrasonic with optics. And the detected photoacoustic signal not only reflects the structural characteristic of tissue but also the metabolic and pathological changes. So, the novel TD based on the PAI is proposed in this paper. Meanwhile, a novel single pulsed laser diode with 905nm wavelength is used as the light source, and a focused ultrasonic transducer with the forward-mode is used to acquire the photoacoustic signal. Finally, PA images were reconstructed with the improved filtered back projection algorithm. Experimental results show the signal acquisition time is less than 0.2 s in each scan of 128 averages. And it is proved that the photoacoustic imaging system for TD with a high-power pulsed laser diode is available. Therefore, this system has the potential value in the biomedical research fields.

  10. Design of a novel pulsed laser diode induced photoacoustic imaging system for tumor diagnosis

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Zeng, Lvming; Liu, Guodong; Huang, Zhen

    2011-11-01

    The tumors are one of most dangerous diseases in lots of diseases Expect for the actively treating of antitumor, the early detection of tumors is a key important step in the course of tumor treatment. Since some drawbacks existed in the traditional methods of tumor detection, such as ultrasound imaging, X radiography, CT imaging, OCT and MRI, etc, a novel hybrid and promising imaging method, that is, photoacoustic imaging (PAI) technology, is used to the tumors diagnosis(TD) in this work. This novel method has higher resolution, contrast and penetration depth due to the merits combination of ultrasonic with optics. And the detected photoacoustic signal not only reflects the structural characteristic of tissue but also the metabolic and pathological changes. So, the novel TD based on the PAI is proposed in this paper. Meanwhile, a novel single pulsed laser diode with 905nm wavelength is used as the light source, and a focused ultrasonic transducer with the forward-mode is used to acquire the photoacoustic signal. Finally, PA images were reconstructed with the improved filtered back projection algorithm. Experimental results show the signal acquisition time is less than 0.2 s in each scan of 128 averages. And it is proved that the photoacoustic imaging system for TD with a high-power pulsed laser diode is available. Therefore, this system has the potential value in the biomedical research fields.

  11. Enhanced vbasis laser diode package

    DOEpatents

    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.

  12. Generation of radio frequency induced metastable xenon as a gain medium for diode pumped rare gas laser systems

    NASA Astrophysics Data System (ADS)

    Andreozzi, Jacqueline Marie

    The pursuit of novel, hybrid methods of achieving lasing from the rare gases has recently been a topic of interest in the field of high energy laser systems. This investigation presents the construction and execution of an experimental setup designed to generate metastable xenon (Xe*) to determine its potential to perform as a high power laser gain medium in a similar capacity as the alkali metals in Diode Pumped Alkali Lasers. A capacitively coupled radio frequency discharge was used to light plasma from naturally abundant xenon, thus exciting the 6s[3/2]2 metastable state. The metastable xenon was probed with a tunable diode laser at 882.2 and 904.8 nanometers, and absorption was detected to verify the presence of Xe* atoms. The absorption profiles are reported with in-depth calculations of the isotope shift and hyperfine structure of each absorption line. Preliminary calculations for the properties of the proposed laser system are also presented.

  13. Novel diode-based laser system for combined transcutaneous monitoring and computer-controlled intermittent treatment of jaundiced neonates

    NASA Astrophysics Data System (ADS)

    Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

    2001-06-01

    The high efficacy of laser phototherapy combined with transcutaneous monitoring of serum bilirubin provides optimum safety for jaundiced infants from the risk of bilirubin encephalopathy. In this paper the authors introduce the design and operating principles of a new laser system that can provide simultaneous monitoring and treatment of several jaundiced babies at one time. The new system incorporates diode-based laser sources oscillating at selected wavelengths to achieve both transcutaneous differential absorption measurements of bilirubin concentration in addition to the computer controlled intermittent laser therapy through a network of optical fibers. The detailed description and operating characteristics of this system are presented.

  14. Versatile subnanosecond laser diode driver

    NASA Astrophysics Data System (ADS)

    Żbik, Mateusz; Wieczorek, Piotr Z.

    2016-09-01

    This article presents a laser diode driver that provides a fast modulation of a laser beam. A pulsed current source was designed and built to test Infra-Red (I-R) receivers in the Time Domain (TD). The proposed solution allows to estimate pulse responses of various photodetectors, whereas the testing was performed with a PiN photodetector. The pulse response brings the information on the behavior of the device under test in a wide frequency range. In addition, an experimental application of the proposed method is presented too. System discussed in this paper has been fully designed and manufactured in Warsaw University of Technology (WUT) in Institute of Electronic Systems (ISE).

  15. Calibrated feedback for laser diodes

    SciTech Connect

    Howard, P.G.

    1986-04-22

    A method is described of calibrating the feedback output from the feedback light detector of the laser diode of an optical disk drive of a laser light pen which consists of mounting a first and a second resistor in a laser light pen; connecting the first resistor between the feedback light detector and ground; connecting the second resistor between the feedback light detector and a feedback output; operating the laser diode to produce a predetermined light power output; adjusting the resistance of the first resistor to produce a predetermined voltage at the feedback output; and adjusting the resistance of the second resistor to produce a predetermined impedance at the feedback output.

  16. A novel control system for automatically locking a diode laser frequency to a selected gas absorption line

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Yin, Wangbao; Ma, Weiguang; Jia, Suotang

    2007-05-01

    A novel control system has been developed for avoiding manual operation during traditional frequency locking. The control system uses a computer with a commercial data acquisition card. This accomplishes the whole operation of frequency locking, including generating ramp, searching locking point, engaging a proportional-integral-differential (PID) regulator at the proper time and outputting PID compensation signal. Moreover, a new method has also been employed to make the novel control system accurately identify the locking points of all absorption lines within the scanning range, so that the laser frequency can be automatically firmly brought onto any selected absorption line centre without any adjusting time. The operation of the system, the ability to identify absorption lines and the performance of the frequency locking were discussed in detail. Successful tests were made with two different lasers: external cavity diode lasers and distributed feedback diode lasers.

  17. 50 Mbps free space direct detection laser diode optical communication system with Q = 4 PPM signaling

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Davidson, Frederic; Field, Christopher

    1990-01-01

    A 50 Mbps direct detection optical communication system for use in an intersatellite link was constructed with an AlGaAs laser diode transmitter and a silicon avalanche photodiode photodetector. The system used a Q = 4 PPM format. The receiver consisted of a maximum likelihood PPM detector and a timing recovery subsystem. The PPM slot clock was recovered at the receiver by using a transition detector followed by a PLL. The PPM word clock was recovered by using a second PLL whose input was derived from the presence of back-to-back PPM pulses contained in the received random PPM pulse sequences. The system achieved a bit error rate of 0.000001 at less than 50 detected signal photons/information bit. The receiver was capable of acquiring and maintaining slot and word synchronization for received signal levels greater than 20 photons/information bit, at which the receiver bit error rate was about 0.01.

  18. A hybrid WDM transport system based on mutually injection-locked Fabry Perot laser diodes

    NASA Astrophysics Data System (ADS)

    Ying, Cheng-Ling; Lu, Hai-Han; Tzeng, Shah-Jye; Ma, Hsien-Li; Chuang, Yao-Wei

    2007-08-01

    A hybrid wavelength-division-multiplexing (WDM) transport system based on mutually injection-locked Fabry-Perot laser diodes (FP LDs) for CATV, 256-QAM and OC-48 transmission is proposed and demonstrated. Mutually injection-locked FP LDs as broadband light source could be relatively simple and cost-effective compared with other demonstrated light source schemes. The proposed hybrid WDM transport system employs four filtered wavelengths (modes) to transmit 111 AM-VSB channels, four 256-QAM digital passband channels, and one OC-48 digital baseband channel simultaneously. Since our proposed system does not use multiple distributed feedback (DFB) LDs, it reveals a prominent one with simpler and more economic advantages.

  19. [Treatment of tracheobronchial malignant tumors using a new high power diode contact laser (GaAlAs) system].

    PubMed

    Ishiguro, Takashi; Sawa, Toshiyuki; Yoshida, Tsutomu; Yokoyama, Mitsuru; Murakawa, Shinji; Azuma, Kenichirou; Tomida, Yoshiteru

    2002-11-01

    We treated ten patients with tracheobronchial malignant tumors using a new high power diode contact laser (GaAlAs) system (DIOMED 25, OLYMPUS) with a flexible bronchofiberscope (OLYMPUS BF IT200 or BF IT240). The total energy of the high power diode laser was 811 J, with a range of 64-3,960 J. With this method 85.7 percent of the symptoms such as dyspnea and hemoptysis were improved, and there was no incidence of massive hemorrhage or serious respiratory failure. The results confirmed the usefulness and safety of this method of treatment for obstructive lesions due to tracheobronchial polypoid malignant tumor and bleeding of the tracheobronchial tree.

  20. [The Research for Trace Ammonia Escape Monitoring System Based on Tunable Diode Laser Absorption Spectroscopy].

    PubMed

    Zhang, Li-fang; Wang, Fei; Yu, Li-bin; Yan, Jian-hua; Cen, Ke-fa

    2015-06-01

    In order to on-line measure the trace ammonia slip of the commercial power plant in the future, this research seeks to measure the trace ammonia by using tunable diode laser absorption spectroscopy under ambient temperature and pressure, and at different temperatures, and the measuring temperature is about 650 K in the power plant. In recent years lasers have become commercially available in the near-infrared where the transitions are much stronger, and ammonia's spectroscopy is pretty complicated and the overlapping lines are difficult to resolve. A group of ammonia transitions near 4 433.5 cm(-1) in the v2 +v3 combination band have been thoroughly selected for detecting lower concentration by analyzing its absorption characteristic and considering other absorption interference in combustion gases where H2O and CO2 mole fraction are very large. To illustrate the potential for NH3 concentration measurements, predictions for NH3, H2O and CO2 are simultaneously simulated, NH3 absorption lines near 4 433.5 cm(-1) wavelength meet weaker H2O absorption than the commercial NH3 lines, and there is almost no CO2 absorption, all the parameters are based on the HITRAN database, and an improved detection limit was obtained for interference-free NH3 monitoring, this 2.25 μm band has line strengths several times larger than absorption lines in the 1.53 μm band which was often used by NH3 sensors for emission monitoring and analyzing. The measurement system was developed with a new Herriott cell and a heated gas cell realizing fast absorption measurements of high resolution, and combined with direct absorption and wavelenguh modulation based on tunable diode laser absorption spectroscopy at different temperatures. The lorentzian line shape is dominant at ambient temperature and pressure, and the estimated detectivity is approximately 0.225 x 10(-6) (SNR = 1) for the directed absorption spectroscopy, assuming a noise-equivalent absorbance of 1 x 10(-4). The heated cell

  1. Diode laser array

    NASA Technical Reports Server (NTRS)

    Carlson, Nils W. (Inventor); Evans, Gary A. (Inventor); Kaiser, Charlie J. (Inventor)

    1990-01-01

    A diode laser array comprises a substrate of a semiconductor material having first and second opposed surfaces. On the first surface is a plurality of spaced gain sections and a separate distributed Bragg reflector passive waveguide at each end of each gain section and optically connecting the gain sections. Each gain section includes a cavity therein wherein charge carriers are generated and recombine to generate light which is confined in the cavity. Also, the cavity, which is preferably a quantum well cavity, provides both a high differential gain and potentially large depth of loss modulation. Each waveguide has a wavelength which is preferably formed by an extension of the cavity of the gain sections and a grating. The grating has a period which provides a selective feedback of light into the gain sections to supporting lasing, which allows some of the light to be emitted from the waveguide normal to the surface of the substrate and which allows optical coupling of the gain sections. Also, the grating period provides an operating wavelength which is on the short wavelength side of the gain period of the gain sections required for laser oscillation. An RF pulse is applied so as to maximize the magnitude of the loss modulation and the differential gain in the gain sections. The array is operated by applying a DC bias to all the gain sections at a level just below the threshold of the gain sections to only one of the gain sections which raises the bias in all of the gain sections to a level that causes all of the gain sections to oscillate. Thus, a small bias can turn the array on and off.

  2. Development of gas fire detection system using tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Y. L.; Li, G.; Yang, T.; Wang, J. J.

    2017-01-01

    The conventional fire detection methods mainly produce an alarm through detecting the changes in smoke concentration, flame radiation, heat and other physical parameters in the environment, but are unable to provide an early warning of a fire emergency. We have designed a gas fire detection system with a high detection sensitivity and high selectivity using the tunable semiconductor diode laser as a light source and combining wavelength modulation and harmonic detection technology. This system can invert the second harmonic signal obtained to obtain the concentration of carbon monoxide gas (a fire characteristic gas) so as to provide an early warning of fire. We reduce the system offset noise and the background noise generated due to the laser interference by deducting the system background spectrum lines from the second harmonic signal. This can also eliminate the interference of other gas spectral lines to a large extent. We detected the concentration of the carbon monoxide gas generated in smoldering sandalwood fire and open beech wood fire with the homemade fire simulator, and tested the lowest detectable limit of system. The test results show that the lowest detectable limit can reach 5×10-6 the system can maintain stable operation for a long period of time and can automatically trigger a water mist fire extinguishing system, which can fully meet the needs of early fire warning.

  3. 400mW output power at 445 nm with narrowband emission from an external cavity diode laser system

    NASA Astrophysics Data System (ADS)

    Ruhnke, Norman; Müller, André; Eppich, Bernd; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Recently, high-power broad-area laser diodes based on GaN with output powers beyond 1 W have become available. However, their broad spectral emission limits their applicability. Due to a lack of internal grating technology for GaN devices, narrowband emission with several hundreds of milliwatts in the blue-green spectral range has not been achieved with laser diodes thus far. In this work, a high-power external cavity diode laser (ECDL) system at 445 nm is presented. The system is based on a commercially available broad-area GaN laser diode and a surface diffraction grating in Littrow configuration for optical feedback. Using this configuration an output power of 400 mW with a reduced spectral emission bandwidth of 20 pm (FWHM) with a side-mode suppression ratio larger than 40 dB is obtained. With the above presented optical output power and narrowband laser emission at 445 nm, the ECDL is well suited as a pump light source for nonlinear frequency conversion into the deep ultraviolet spectral range.

  4. Activation of theMercury Laser System: A Diode-Pumped Solid-State Laser Driver for Inertial Fusion

    SciTech Connect

    Bayramian, A J; Beach, R J; Bibeau, C; Ebbers, C A; Freitas, B L; Kanz, V K; Payne, S A; Schaffers, K I; Skulina, K M; Smith, L K; Tassano, J B

    2001-09-10

    Initial measurements are reported for the Mercury laser system, a scalable driver for rep-rated inertial fusion energy. The performance goals include 10% electrical efficiency at 10 Hz and 100 J with a 2-10 ns pulse length. We report on the first Yb:S-FAP crystals grown to sufficient size for fabricating full size (4 x 6 cm) amplifier slabs. The first of four 160 kW (peak power) diode arrays and pump delivery systems were completed and tested with the following results: 5.5% power droop over a 0.75 ms pulse, 3.95 nm spectral linewidth, far field divergence of 14.0 mrad and 149.5 mrad in the microlensed and unmicrolensed directions respectively, and 83% optical-to-optical transfer efficiency through the pump delivery system.

  5. Diode laser and endoscopic laser surgery.

    PubMed

    Sullins, Kenneth E

    2002-05-01

    Two functionally important differences exist between the diode laser and the carbon dioxide (CO2) laser (used more commonly in small animal surgery). Diode laser energy is delivered through a quartz fiber instead of being reflected through an articulated arm or waveguide. Quartz fibers are generally more flexible and resilient than waveguides and can be inserted through an endoscope for minimally invasive procedures. Laser-tissue interaction is the other significant difference. The CO2 laser is completely absorbed by water, which limits the effect to visible tissue. The diode wavelength is minimally absorbed by water and may affect tissue as deep as 10 mm below the surface in the free-beam mode. With proper respect for the tissue effect, these differences can be used to the advantage of the patient.

  6. A tunable diode laser system for aircraft measurements of trace gases

    NASA Technical Reports Server (NTRS)

    Schiff, H. I.; Karecki, D. R.; Harris, G. W.; Mackay, G. I.; Hastie, D. R.

    1990-01-01

    The advantages of tunable-diode-laser absorption spectrometry (TDLAS) for measuring trace atmospheric gases are universality, positive identification, good sensitivity, and rapid response time. A TDLAS system is described which is capable of making measurements aboard an aircraft. The instrument was employed during the Chemical Instrumentation Test and Evaluation (CITE) 2 program to measure NO2 on 11 flights and HNO3 on five flights. Detection limits were determined to be 25 parts per trillion by volume (pptv) for NO2 and 75 pptv for HNO3 with response times of 3 min. This was sufficient to permit measurements of NO2 in the free troposphere and HNO3 in the continental boundary layer a significant fraction of the time.

  7. Space Launch System Base Heating Test: Tunable Diode Laser Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Parker, Ron; Carr, Zak; MacLean, Mathew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  8. Space Launch System Base Heating Test: Tunable Diode Laser Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Parker, Ron; Carr, Zak; MacLean, Matthew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  9. Cover slip external cavity diode laser.

    PubMed

    Carr, Adra V; Sechrest, Yancey H; Waitukaitis, Scott R; Perreault, John D; Lonij, Vincent P A; Cronin, Alexander D

    2007-10-01

    A 671 nm diode laser with a mode-hop-free tuning range of 40 GHz is described. This long tuning range is achieved by simultaneously ramping the external cavity length with the laser injection current. The laser output pointing remains fixed, independent of its frequency because of the cover slip cavity design. This system is simple, economical, robust, and easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium atom beam experiments.

  10. Cost-effective optoacoustic system based on the combination of high-power diode lasers

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  11. Compact double optical feedback external-cavity diode laser system and its frequency stabilization

    NASA Astrophysics Data System (ADS)

    Doi, Kohei; Minabe, Yuta; Sato, Takashi; Maruyama, Takeo; Ohkawa, Masashi; Tsubokawa, Tsuneya

    2007-02-01

    External cavity diode laser (ECDL) systems are presently experiencing a surge in popularity as laser light-sources, in advanced optical communications- and measurement-systems. Because such systems require that their external reflectors be precisely controlled, to eliminate low frequency fluctuations (LFF) in optical output, we conducted experiments with a two-cavity version, which easily eliminated LFFs, as expected. The technique has the added advantage of a narrower oscillation-linewidth than would be achievable, using a single optical feedback. However, the ECDL's oscillation frequency is susceptible to the influences of the drive-current, as well as changes, both in the refractive index, and the overall length of the external reflector that results from fluctuations in atmospheric temperature. We made every effort to maintain the length of the ECDL cavity, while evaluating oscillation-frequency stability. We used a Super-Invar board as the platform for our compact ECDL system to minimize the influence of thermal expansion, because of its low expansion coefficient. We then compared the effect of atmospheric temperature variations between two experimental conditions, with the Super-invar board and without it, and finally took note of the improvement in performance, using the board.

  12. Laser diode pumped solid state laser

    SciTech Connect

    Baer, T.M.; Keirstead, M.S.

    1987-04-07

    This patent describes a high-efficiency, laser diode pumped array, frequency doubled, compact solid state laser, comprising: a rare earth doped birefringent solid laser rod selected from the group consisting of Nd:YLF, Nd:YALO having a front end and a back end, the rod producing a polarized output beam; a housing with means holding the laser rod in fixed position in the housing with its front end forward; a laser array having a predetermined wavelength pumping the laser rod, having a output frequency sufficiently matched to the laser rod to pump the laser rod, secured in the housing behind and in optical alignment with the rod; laser cavity means defining a laser cavity mounted in the housing with the laser rod positioned within the cavity, the laser cavity means further including within the cavity an output coupler means; a frequency doubler, positioned to receive a suitably polarized output beam from the laser rod and to halve its wavelength and double its frequency; a polarization means for polarizing the output beam of the laser rod and substantially maintaining a polarization which optimizes frequency doubling at the frequency doubler and means for matching a focused image of the laser diode with a lasing volume of the laser cavity.

  13. New laser materials for laser diode pumping

    NASA Technical Reports Server (NTRS)

    Jenssen, H. P.

    1990-01-01

    The potential advantages of laser diode pumped solid state lasers are many with high overall efficiency being the most important. In order to realize these advantages, the solid state laser material needs to be optimized for diode laser pumping and for the particular application. In the case of the Nd laser, materials with a longer upper level radiative lifetime are desirable. This is because the laser diode is fundamentally a cw source, and to obtain high energy storage, a long integration time is necessary. Fluoride crystals are investigated as host materials for the Nd laser and also for IR laser transitions in other rare earths, such as the 2 micron Ho laser and the 3 micron Er laser. The approach is to investigate both known crystals, such as BaY2F8, as well as new crystals such as NaYF8. Emphasis is on the growth and spectroscopy of BaY2F8. These two efforts are parallel efforts. The growth effort is aimed at establishing conditions for obtaining large, high quality boules for laser samples. This requires numerous experimental growth runs; however, from these runs, samples suitable for spectroscopy become available.

  14. Quantum Noise in Laser Diodes

    NASA Technical Reports Server (NTRS)

    Giacobino, E.; Marin, F.; Bramati, A.; Jost, V.; Poizat, J. Ph.; Roch, J.-F.; Grangier, P.; Zhang, T.-C.

    1996-01-01

    We have investigated the intensity noise of single mode laser diodes, either free-running or using different types of line narrowing techniques at room temperature. We have measured an intensity squeezing of 1.2 dB with grating-extended cavity lasers and 1.4 dB with injection locked lasers (respectively 1.6 dB and 2.3 dB inferred at the laser output). We have observed that the intensity noise of a free-running nominally single mode laser diode results from a cancellation effect between large anti-correlated fluctuations of the main mode and of weak longitudinal side modes. Reducing the side modes by line narrowing techniques results in intensity squeezing.

  15. A Hertz-Linewidth Ultrastable Diode Laser System for Clock Transition Detection of Strontium Atoms

    NASA Astrophysics Data System (ADS)

    Li, Ye; Lin, Yi-Ge; Wang, Qiang; Wang, Shao-Kai; Zhao, Yang; Meng, Fei; Lin, Bai-Ke; Cao, Jian-Ping; Li, Tian-Chu; Fang, Zhan-Jun; Zang, Er-Jun

    2014-02-01

    The frequencies of two 698 nm external cavity diode lasers (ECDLs) are locked separately to two independently located ultrahigh finesse optical resonant cavities with the Pound—Drever—Hall technique. The linewidth of each ECDL is measured to be ~4.6 Hz by their beating and the fractional frequency stability below 5 × 10-15 between 1 s to 10 s averaging time. Another 698 nm laser diode is injection locked to one of the cavity-stabilized ECDLs with a fixed frequency offset for power amplification while maintaining its linewidth and frequency characteristics. The frequency drift is ~1 Hz/s measured by a femtosecond optical frequency comb based on erbium fiber. The output of the injection slave laser is delivered to the magneto-optical trap of a Sr optical clock through a 10-m-long single mode polarization maintaining fiber with an active fiber noise cancelation technique to detect the clock transition of Sr atoms.

  16. Primary investigations on the potential of a novel diode pumped Er:YAG laser system for middle ear surgery

    NASA Astrophysics Data System (ADS)

    Stock, Karl; Wurm, Holger; Hausladen, Florian

    2016-02-01

    Flashlamp pumped Er:YAG lasers are successfully used clinically for both precise soft and hard tissue ablation. Since several years a novel diode pumped Er:YAG laser system (Pantec Engineering AG) is available, with mean laser power up to 40 W and pulse repetition rate up to 1 kHz. The aim of the study was to investigate the suitability of the laser system specifically for stapedotomy. Firstly an experimental setup was realized with a beam focusing unit and a computer controlled translation stage to move the samples (slices of porcine bone) with a defined velocity while irradiation with various laser parameters. A microphone was positioned in a defined distance to the ablation point and the resulting acoustic signal of the ablation process was recorded. For comparison, measurements were also performed with a flash lamp pumped Er:YAG laser system. After irradiation the resulting ablation quality and efficacy were determined using light microscopy. Using a high speed camera and "Töpler-Schlierentechnik" the cavitation bubble in water after perforation of a bone slice was investigated. The results show efficient bone ablation using the diode pumped Er:YAG laser system. Also a decrease of the sound level and of the cavitation bubble volume was observed with decreasing pulse duration. Higher repetition rates lead to a slightly increase of thermal side effects but have no influence on the ablation efficiency. In conclusion, these first experiments demonstrate the high potential of the diode pumped Er:YAG laser system for use in middle ear surgery.

  17. Computer processing of tunable diode laser spectra

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1989-01-01

    A computer-controlled tunable diode laser spectrometer and spectral analysis software are described. The three-channel system records simultaneously the transmission of a subject gas, a temperature-stabilized etalon, and a calibration gas. The software routines are applied to diode laser spectra of HNO3 and NO2 to illustrate the procedures adopted for conversion of raw spectral data to useful transmission and harmonic spectra. Extraction of line positions, absorption intensities, collisional broadening coefficients, and gas concentrations from recorded spectra is also described.

  18. Optical tweezers using a diode laser

    NASA Astrophysics Data System (ADS)

    Afzal, Robert S.; Treacy, E. Brian

    1992-04-01

    Simple modifications were made to a commercial microscope to enable injection of light from a diode laser, and demonstrate optical tweezers action. The basic properties of microscope optics are presented together with discussion of principles to be followed in arranging the external optics for achieving useful tweezers. Procedures using a single-mode diode laser along with experimental results are presented in enough detail to permit readers to make their own system for trapping and manipulating single cells. It is surprisingly easy to demonstrate tweezers action once some basic concepts are understood.

  19. High power, high reliability laser diodes

    NASA Astrophysics Data System (ADS)

    Scifres, D. R.; Welch, D. F.; Craig, R. R.; Zucker, E.; Major, J. S.; Harnagel, G. L.; Sakamoto, M.; Haden, J. M.; Endriz, J. G.; Kung, H.

    1992-06-01

    Results are presented on catastrophic damage limits and life-test measurements for four types of high-power laser diodes operating at wavelengths between 980 nm and 690 nm. The laser diodes under consideration are CW multimode lasers, CW laser bars, quasi-CW bars/2D stacked arrays, and single transverse mode lasers.

  20. Optical logic inverter and AND elements using laser or light-emitting diodes and photodetectors in a bistable system.

    PubMed

    Okumura, K; Ogawa, Y; Ito, H; Inaba, H

    1984-11-01

    Fundamental optical digital data-processing functions of optical inverter and optical AND elements are proposed and demonstrated experimentally for the first reported time using light-emitting diodes and a photodetector in a hybrid optoelectronic bistable system. The inherent simplicity of these bistable optical devices that use either a laser or a light-emitting diode should make it possible to realize these optical logic functions by monolithic optoelectronic integration. Specific integration schemes are also proposed, and future interesting and useful applications are discussed.

  1. [System parameters selection and optimization of tunable diode laser absorption spectroscopy].

    PubMed

    Gao, Nan; Du, Zhen-Hui; Tang, Mia; Yang, Jie-Wen; Yang, Chun-Mei; Wang, Yan

    2010-12-01

    The system performance of tunable diode laser absorption spectroscopy (TDLAS) is affected by the modulation parameters such as modulation index, modulation frequency, scanning amplitude and scanning frequency. There is a lack of definite parameters selection basis in practical measurement. Aiming at this problem, the influence of modulation parameters on second harmonic signals was observed by experiment based on a certain theory in the present paper, and the basis and method of modulation parameters optimization for various system functions and demands were summarized by analyzing the signal characteristic including amplitude, signal to noise ratio, symmetry and peak width. For the system of concentration or temperature detection the amplitude and signal to noise ratio will be taken into prior consideration which require optimum modulation index, lower modulation frequency and lower scanning frequency. In condition of pressure detection deduced by lineshape the signal symmetry and peak width are more important to ascertain the modulation parameters according to practical demands. Scanning amplitude will be adjusted to obtain complete signal waveforms, then scanning frequency can be adjusted according to system speed and accuracy requirement. The result of the experiment provided a definite basis for conforming the working state of such system.

  2. Improvement and evaluation of a low-cost laser diode photoacoustic microscopy system for ovarian tissue imaging

    NASA Astrophysics Data System (ADS)

    Erfanzadeh, Mohsen; Salehi, Hassan S.; Kumavor, Patrick; Zhu, Quing

    2016-03-01

    We present a laser diode-based photoacoustic microscopy (PAM) system with a minimized light intensity loss for ovarian tissue imaging. A 905 nm, 650 W output peak power pulsed laser diode (PLD) is utilized as the light source. The intrinsic properties and the construction of this PLD typically make it challenging to focus its beam to a small spot size with a lowloss optical system. An optical system comprising a combination of aspheric and cylindrical lenses is presented that allows a low-loss collimation and tight focusing of the light beam. The lateral resolution of this PAM system is measured to be 40 μm using edge spread function estimation. Images of black human hairs, polyethylene tubes filled with rat blood, ex vivo mouse ear and ex vivo porcine ovary are presented.

  3. Diode laser-based sensor system for long-path absorption measurements of atmospheric concentration and near-IR molecular spectral parameters

    SciTech Connect

    Goldstein, N.; Lee, J.; Adler-Golden, S.M.; Bien, F.

    1993-12-31

    Line-locked near-IR diode lasers and a simple retroreflector/telescope system were used for remote sensing of atmospheric constituents over long atmospheric paths. The experimental configuration used in preliminary measurements of atmospheric water vapor and oxygen with AlGaAs diode lasers is presented. A prototype field sensor system currently under development shares the same basic configuration but incorporates interchangeable AlGaAs and InGaAsP diode-laser modules for monitoring a variety of atmospheric gases.

  4. A three-beam water vapor sensor system for combustion diagnostics using a 1390 nm tunable diode laser

    SciTech Connect

    Wang, L.G.; Vay, S.

    1995-12-31

    H{sub 2}O(v) is an important species in combustion and hypersonic flow measurements because it is a primary combustion product. Measurements of water vapor can be used to determine performance parameters, such as extent and efficiency of combustion in propulsion and aerodynamics facilities. Water vapor concentration measurement in these high-temperature hypervelocity combustion conditions requires very high sensitivity and fast time response. A three-beam diode laser H{sub 2}O(v) measurement system for nonintrusive combustion diagnostics has been developed at NASA Langley Research Center and successfully tested and installed at GASL NASA HYPULSE facility for routine operation. The system was built using both direct laser absorption spectroscopy and frequency modulation laser spectroscopy. The output beam from a distributed feedback (DFB) InGaAsP diode laser (emitting around 1.39 {micro}m) is split into three equal-powered equal-distanced parallel beams with separation of 9 mm. With three beams, the authors are able to obtain water vapor number densities at three locations. Frequency modulation spectroscopy technique is used to achieve high detection sensitivity. The diode laser is modulated at radio frequency (RF), while the wavelength of the diode laser is tuned to scan over a strong water vapor absorption line. The detected RF signal is then demodulated at the fundamental frequency of the modulation (one-F demodulation). A working model and a computer software code have been developed for data process and data analysis. Water vapor number density measurements are achieved with consideration of temperature dependence. Experimental results and data analysis will be presented.

  5. Modeling and simulation of dispersion-limited fiber communication systems employing directly modulated laser diodes

    NASA Astrophysics Data System (ADS)

    Ahmed, M.

    2012-11-01

    This paper quantifies the role played by fiber dispersion in limiting the transmission distance in directly modulated gigabit optical fiber communication systems (OFCSs). The study is based on modeling and simulation of an OFCS deploying a directly modulated 1.55-μm distributed feedback InGaAsP laser diode, a single-mode fiber and a PIN photodetector. The repeater distance of the system is decided to correspond to a bit error rate of 10-9. The receiver sensitivity corresponding to the back-to-back configuration is calculated. Fiber attenuation was found to limit the maximum transmission distance to 162-202 km under bit rates ranging between 1 and 10 Gbps. This distance was found to be less affected by counting the chromatic dispersion of the fiber up to bit rate of 2 Gbps. A dramatic decrease in the transmission distance is predicted when the bit rate increases further and the system becomes dispersion limited. Influence of dispersion on the transmission distance is quantified in terms of the power penalty of the OFCS system associated with taking account of fiber dispersion. This power penalty is predicted to be within 7 dB for bit rates below 5 Gbps but jumps to values as high as 22 dB at higher bit rates.

  6. Simultaneous measurements of total hemoglobin concentration and blood oxygenation with laser diode-based optoacoustic system

    NASA Astrophysics Data System (ADS)

    Petrov, Irene Y.; Prough, Donald S.; Petrov, Yuriy; Henkel, S. Nan; Seeton, Roger; Esenaliev, Rinat O.

    2017-03-01

    Noninvasive, accurate, continuous monitoring of multiple variables, including blood oxygenation, i.e. oxyhemoglobin saturation (SO2) and total hemoglobin concentration (THb) in both high acuity and low acuity environments would greatly facilitate prompt diagnosis and treatment of physiologic derangements. However, most of the existing techniques for patient monitoring are invasive, while noninvasive techniques often fail to provide accurate measurements. We built a compact, multi-wavelength, nanosecond, fiber-coupled laser diode-based optoacoustic system for noninvasive, accurate monitoring of blood SO2 and THb in veins and arteries. We tested the system by probing the radial artery of healthy volunteers. Using blood samples obtained by venipuncture, we also measured a reference THb for each volunteer. Moreover, the optoacoustic data were compared with that obtained from a commercially available noninvasive monitor for measurements of these variables. The optoacoustic system provided rapid, simultaneous, and continuous measurement of THb and SO2 with high precision. The obtained results are promising and we plan to further test the system in clinical studies and at conditions simulating circulatory shock.

  7. Investigations on the potential of a low power diode pumped Er:YAG laser system for oral surgery

    NASA Astrophysics Data System (ADS)

    Stock, Karl; Wurm, Holger; Hausladen, Florian; Wagner, Sophia; Hibst, Raimund

    2015-02-01

    Flash lamp pumped Er:YAG-lasers are used in clinical practice for dental applications successfully. As an alternative, several diode pumped Er:YAG laser systems (Pantec Engineering AG) become available, with mean laser power of 2W, 15W, and 30W. The aim of the presented study is to investigate the potential of the 2W Er:YAG laser system for oral surgery. At first an appropriate experimental set-up was realized with a beam delivery and both, a focusing unit for non-contact tissue cutting and a fiber tip for tissue cutting in contact mode. In order to produce reproducible cuts, the samples (porcine gingiva) were moved by a computer controlled translation stage. On the fresh samples cutting depth and quality were determined by light microscopy. Afterwards histological sections were prepared and microscopically analyzed regarding cutting depth and thermal damage zone. The experiments show that low laser power ≤ 2W is sufficient to perform efficient oral soft tissue cutting with cut depth up to 2mm (sample movement 2mm/s). The width of the thermal damage zone can be controlled by the irradiation parameters within a range of about 50μm to 110μm. In general, thermal injury is more pronounced using fiber tips in contact mode compared to the focused laser beam. In conclusion the results reveal that even the low power diode pumped Er:YAG laser is an appropriate tool for oral surgery.

  8. "Diode Pumped Solid State Lasers At 2 And 3 µm"

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon

    1988-06-01

    The most attractive alternative to flashlamp pumping of solid state lasers is the diode laser. In the past two decades numerous laboratory devices have been assembled which incorporated single diode lasers, small laser diode arrays or LED's for pumping of Nd:YAG, Nd:glass and a host of other Nd lasers. The low power output, low packaging density, and extremely high cost of diode lasers prevented any serious applications for laser pumping in the past. The reason for the continued interest in this area stems from the potential dramatic increase in system efficiency and component lifetime, and reduction of thermal load of the solid-state laser material. The latter not only will reduce thereto-optic effects and therefore lead to better beam quality but also will enable an increase in pulse repetition frequency. The attractive operating parameters combined with low voltage operation and the compactness of an all solid-state laser system have a potential high payoff. The high pumping efficiency compared to flashlamps stems from the good spectral match between the laser diode emission and the rare earth activator absorption bands. A significant advantage of laser diode pumping compared to arc lamps is system lifetime and reliability. Laser diode arrays have exhibited lifetimes on the order of 10,000 hours in cw operation and 109 shots in the pulsed mode. Flashlamp life is on the order of 107 shots, and about 200 hours for cw operation. In addition, the high pump flux combined with a substantial UV content in lamp pumped systems causes material degradation in the pump cavity and in the coolant. Such problems are virtually eliminated with laser diode pump sources. The absence of high voltage pulses, high temperatures and UV radiation encountered with arc lamps leads to much more benign operating features for solid state laser systems employing laser diode pumps. Laser diode technology dates back to 1962 when laser action in GaAs diodes was first demonstrated. However, it

  9. System analysis of wavelength beam combining of high-power diode lasers for photoacoustic endoscopy

    NASA Astrophysics Data System (ADS)

    Leggio, Luca; Gallego, Daniel C.; Gawali, Sandeep B.; Sánchez, Miguel; Rodriguez, Sergio; Osiński, Marek; Sacher, Joachim; Carpintero, Guillermo; Lamela, Horacio

    2016-04-01

    This paper, originally published on 27 April 2016, was replaced with a corrected/revised version on 8 June 2016. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance. The purpose of wavelength-beam combining (WBC) is to improve the output power of a multi-wavelength laser system while maintaining the quality of the combined beam. This technique has been primarily proposed for industrial applications, such as metal cutting and soldering, which require optical peak power between kilowatts and megawatts. In order to replace the bulkier solid-state lasers, we propose to use the WBC technique for photoacoustic (PA) applications, where a multi-wavelength focused beam with optical peak power between hundreds of watts up to several kilowatts is necessary to penetrate deeply into biological tissues. In this work we present an analytical study about the coupling of light beams emitted by diode laser bars at 808 nm, 880 nm, 910 nm, 940 nm, and 980 nm into a < 600-μm core-diameter optical fiber for PA endoscopy. In order to achieve an efficient coupling it is necessary to collimate the beams in both fast and slow axes by means of cylindrical lenses and to use partial reflection mirrors at 45° tilt. We show an example of beam collimation using cylindrical lenses in both fast and slow axes. In a real PA scenario, the resulting beam should have a sufficient peak power to generate significant PA signals from a turbid tissue>.

  10. Diode Laser Application in Soft Tissue Oral Surgery

    PubMed Central

    Azma, Ehsan; Safavi, Nassimeh

    2013-01-01

    Introduction: Diode laser with wavelengths ranging from 810 to 980 nm in a continuous or pulsed mode was used as a possible instrument for soft tissue surgery in the oral cavity. Discussion: Diode laser is one of laser systems in which photons are produced by electric current with wavelengths of 810, 940 and 980nm. The application of diode laser in soft tissue oral surgery has been evaluated from a safety point of view, for facial pigmentation and vascular lesions and in oral surgery excision; for example frenectomy, epulis fissuratum and fibroma. The advantages of laser application are that it provides relatively bloodless surgical and post surgical courses with minimal swelling and scarring. We used diode laser for excisional biopsy of pyogenic granuloma and gingival pigmentation. Conclusion: The diode laser can be used as a modality for oral soft tissue surgery PMID:25606331

  11. Semiconductor Laser Diodes and the Design of a D.C. Powered Laser Diode Drive Unit

    DTIC Science & Technology

    1988-06-01

    i FILE c(OP!; NAVAL POSTGRADUATE SCHOOL Monterey, California 00 ,, STAES THESIS SEMICONDUCTOR LASER DIODES AND THE DESIGN OF A D.C. POWERED LASER...the design of a laser diode modulation circuit is the determination of the input imped- ence and equivalent circuit of the laser diode and packag- ing...current source with a high internal impedance as compared to the input imped- ance of the laser. [Ref. l:p. 33] Summarizing the above, laser diodes

  12. Variable FOV optical illumination system with constant aspect ratio for 2-D array lasers diodes

    NASA Astrophysics Data System (ADS)

    Arasa, J.; de la Fuente, M. C.; Ibañez, C.

    2008-09-01

    In this contribution we present a compact system to create an illumination distribution with a constant aspect ratio 3:4 and FOV from 0.4 to 1 degree. Besides, the system must delivery 40 W from 170 individual laser diodes placed in a regular 2-D array distribution of 10 x 20 mm. The main problem that must be solved is the high asymmetry of the individual sources; emission divergence's ratio 3:73 (0.3 vs. 7.4 degree) combined with the flux holes due to the laser's heat drain. In one axis (divergence of 0.3º) the best design strategy approach is a Galileo telescope but in the other axis a collimator configuration is the best solution. To manage both solutions at the same time is the aim of this contribution. Unfortunately for the Galileo strategy, source dimensions are too large so aspheric surfaces are needed, and the collimator configuration requires an EFL that must change from 573 to 1432 mm. The presented solution uses a set of three fixed anamorphic lenses, two of them pure cylinders, combined with a wheel of anamorphic lenses that have the function to change the FOV of the system. The most important contribution of the design is to obtain a constant final ratio 3:4 from an initial ratio of 3:73 with no losses of energy. The proposed solution produces an illumination pattern with peaks and valleys lower than 40%. This pattern distribution might be unacceptable for a standard illumination solution. However, the actual FOV is used to illuminate far away targets thus air turbulence is enough to homogenize the distribution on the target.

  13. Alternative laser system for cesium magneto-optical trap via optical injection locking to sideband of a 9-GHz current-modulated diode laser.

    PubMed

    Diao, Wenting; He, Jun; Liu, Zhi; Yang, Baodong; Wang, Junmin

    2012-03-26

    By optical injection of an 852-nm extended-cavity diode laser (master laser) to lock the + 1-order sideband of a ~9-GHz-current-modulated diode laser (slave laser), we generate a pair of phase-locked lasers with a frequency difference up to ~9-GHz for a cesium (Cs) magneto-optical trap (MOT) with convenient tuning capability. For a cesium MOT, the master laser acts as repumping laser, locked to the Cs 6S₁/₂ (F = 3) - 6P₃/₂ (F' = 4) transition. When the + 1-order sideband of the 8.9536-GHz-current-modulated slave laser is optically injection-locked, the carrier operates on the Cs 6S₁/₂ (F = 4) - 6P₃/₂ (F' = 5) cooling cycle transition with -12 MHz detuning and acts as cooling/trapping laser. When carrying a 9.1926-GHz modulation signal, this phase-locked laser system can be applied in the fields of coherent population trapping and coherent manipulation of Cs atomic ground states.

  14. Characterization of an external cavity diode laser based ring cavity NICE-OHMS system.

    PubMed

    Bell, C L; Hancock, G; Peverall, R; Ritchie, G A D; van Helden, J H; van Leeuwen, N J

    2009-06-08

    The performance of an external cavity diode laser based noise immune cavity enhanced optical heterodyne molecular spectrometer is presented. To reduce the noise on the signal a ring cavity and a circuit to remove residual amplitude modulation on the pre-cavity laser radiation was implemented. We demonstrate a sensitivity of 4 x 10(-11) cm(-1) Hz(-1/2) using a cavity with a finesse of 2600 on a Doppler-broadened transition of CH(4) at 6610.063 cm(-1).

  15. High power diode and solid state lasers

    NASA Astrophysics Data System (ADS)

    Eichler, H. J.; Fritsche, H.; Lux, O.; Strohmaier, S. G.

    2017-01-01

    Diode lasers are now basic pump sources of crystal, glass fiber and other solid state lasers. Progress in the performance of all these lasers is related. Examples of recently developed diode pumped lasers and Raman frequency converters are described for applications in materials processing, Lidar and medical surgery.

  16. IC Fabrication Methods Improve Laser Diodes

    NASA Technical Reports Server (NTRS)

    Miller, M.; Pickhardt, V.

    1984-01-01

    Family of high-performance, tunable diode lasers developed for use as local oscillators in passive laser heterodyne spectrometer. Diodes fabricated using standard IC processes include photolithography, selective etching and vacuum deposition of metals and insulators. Packaging refinements improved thermal-cycling characteristics of diodes and increased room-temperature shelf life.

  17. Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm).

    PubMed

    Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

    2017-04-01

    The aim of this in vitro study was to evaluate the effect of radiant heat on surface hardness of three conventional glass ionomer cements (GICs) by using a blue diode laser system (445 nm) and a light-emitting diode (LED) unit. Additionally, the safety of the laser treatment was evaluated. Thirty disk-shaped specimens were prepared of each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: group 1 was the control group of the study; in group 2, the specimens were irradiated for 60 s at the top surface using a LED light-curing unit; and in group 3, the specimens were irradiated for 60 s at the top surface using a blue light diode laser system (445 nm). Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests at a level of significance of a = 0.05. Radiant heat treatments, with both laser and LED devices, increased surface hardness (p < 0.05) but in different extent. Blue diode laser treatment was seemed to be more effective compared to LED treatment. There were no alterations in surface morphology or chemical composition after laser treatment. The tested radiant heat treatment with a blue diode laser may be advantageous for the longevity of GIC restorations. The safety of the use of blue diode laser for this application was confirmed.

  18. Diode laser-pumped solid-state lasers

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1988-01-01

    An evaluation is made of the consequences for solid-state lasers of novel diode laser-pumping technology. Diode laser-pumped neodymium lasers have operated at an electrical-to-optical efficiency of 10 percent in a single spatial mode, with linewidths of less than 10 kHz, and with a spectral power brightness sufficiently great to allow frequency extension by harmonic generation in nonlinear crystals; this has yielded green and blue sources of coherent radiation. Q-switched operation with kW peak powers and mode-locked operation with 10-picosec pulse widths have also been demonstrated. All-solid-state lasers at prices comparable to those of current flash-lamp-pumped laser systems are foreseen, as are power levels exceeding 1 kW, for coherent radar, global satellite sensing, and micromachining.

  19. Diode laser-pumped solid-state lasers

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1988-01-01

    An evaluation is made of the consequences for solid-state lasers of novel diode laser-pumping technology. Diode laser-pumped neodymium lasers have operated at an electrical-to-optical efficiency of 10 percent in a single spatial mode, with linewidths of less than 10 kHz, and with a spectral power brightness sufficiently great to allow frequency extension by harmonic generation in nonlinear crystals; this has yielded green and blue sources of coherent radiation. Q-switched operation with kW peak powers and mode-locked operation with 10-picosec pulse widths have also been demonstrated. All-solid-state lasers at prices comparable to those of current flash-lamp-pumped laser systems are foreseen, as are power levels exceeding 1 kW, for coherent radar, global satellite sensing, and micromachining.

  20. 1064-nm DFB laser diode modules applicable to seeder for pulse-on-demand fiber laser systems

    NASA Astrophysics Data System (ADS)

    Yokoyama, Yoshitaka; Takada, Kan; Kageyama, Takeo; Tanaka, Shin; Kondo, Hayato; Kanbe, Satoshi; Maeda, Yasunari; Mochida, Reio; Nishi, Kenichi; Yamamoto, Tsuyoshi; Takemasa, Keizo; Sugawara, Mitsuru; Arakawa, Yasuhiko

    2014-12-01

    Semiconductor DFB (Distributed feedback) laser diodes with an operating wavelength of 1064 nm, which is suitable for pulse-on-demand fiber laser, have been developed. The stable performance of CW and nanosecond/picosecond pulsed operation is reviewed. By applying gain-switching operation with a simple direct modulation technique, 50-ps pulse generation with a stable spectral single-mode property was obtained. For the efficient amplification of the obtained 50-ps pulse, a monolithic semiconductor optical amplifier (SOA) was integrated into the DFB lasers. An improved peak power of 300 mW at 50-ps pulse was observed with limited optical noise injection when the synchronous modulation technique of the DFB and the SOA was employed. Short cavity lasers showed a high-frequency response compared to the original DFB lasers and achieved a short pulse width of 13 ps by standard gain-switched operation.

  1. Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

    DTIC Science & Technology

    2012-09-01

    101 325 Pa = 760 Torr † NIST 2006 CODATA recommended values 98 Appendix B. Alkali Data Potassium Properties Table 3. Potassium (K) physical...INVESTIGATION OF DIODE PUMPED ALKALI LASER ATMOSPHERIC TRANSMISSION USING TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY DISSERTATION Christopher A... ALKALI LASER ATMOSPHERIC TRANSMISSION USING TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY DISSERTATION Presented to the Faculty Graduate School of

  2. Linear diode laser bar optical stretchers for cell deformation

    PubMed Central

    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

  3. Development of visible diode-laser/fiber-optic colorimetric system for the simple and inexpensive quantification of a protein

    NASA Astrophysics Data System (ADS)

    Kim, SungHo; Noh, Young S.; Byun, Gill S.; Jang, Sung-Keun

    1998-04-01

    A simple and inexpensive quantitative detection of protein in one droplet solution was achieved by a portable diode-laser- based-optical-fiber absorption spectrometry. A system consisted of a visible diode laser, a photodiode and a pair of optical fibers. The conventional Lowry method was used to measure the blue-colored protein solutions. In this study, one droplet of sample, which filled up the void between the end surfaces of two optical fibers, served as a sample cell. The volume of a droplet was 50 (mu) L, which is 1/100 of the cuvette of UV/VIS spectrometer cell used in Lowry method. Although the required sample volume decreased up to 100 times, the detection range was comparable to that of conventional Lowry method in the range of g/L - mg/L.

  4. Algorithm for evaluation of temperature distribution of a vapor cell in a diode-pumped alkali laser system (part II).

    PubMed

    Han, Juhong; Wang, You; Cai, He; An, Guofei; Zhang, Wei; Xue, Liangping; Wang, Hongyuan; Zhou, Jie; Jiang, Zhigang; Gao, Ming

    2015-04-06

    With high efficiency and small thermally-induced effects in the near-infrared wavelength region, a diode-pumped alkali laser (DPAL) is regarded as combining the major advantages of solid-state lasers and gas-state lasers and obviating their main disadvantages at the same time. Studying the temperature distribution in the cross-section of an alkali-vapor cell is critical to realize high-powered DPAL systems for both static and flowing states. In this report, a theoretical algorithm has been built to investigate the features of a flowing-gas DPAL system by uniting procedures in kinetics, heat transfer, and fluid dynamic together. The thermal features and output characteristics have been simultaneously obtained for different gas velocities. The results have demonstrated the great potential of DPALs in the extremely high-powered laser operation.

  5. Noninvasive blood glucose monitoring with laser diode

    NASA Astrophysics Data System (ADS)

    Zhang, Xiqin; Chen, Jianhong; Ooi, Ean Tat; Yeo, Joon Hock

    2006-02-01

    The non-invasive measurement of blood sugar level was studied by use of near infrared laser diodes. The in vitro and in vivo experiments were carried out using six laser diodes having wavelengths range from 1550 nm to 1750nm. Several volunteers were tested for OGTT (Oral Glucose Tolerance Test) experiment. We took blood from a fingertip and measured its concentration with a glucose meter while taking signal voltage from laser diodes system. The data of signal voltage were processed to do calibration and prediction; in this paper PLS (Partial Least Square) method was used to do modeling. For in vitro experiment, good linear relationship between predicted glucose concentration and real glucose concentration was obtained. For in vivo experiments, we got the blood sugar level distributions in Clarke error grid that is a reference for doctors to do diagnosis and treatment. In the Clarke error grid, 75% of all data was in area A and 25 % was in area B. From the in vitro and in vivo results we know that multiple laser diodes are suitable for non-invasive blood glucose monitoring.

  6. Laser source for dimensional metrology: investigation of an iodine stabilized system based on narrow linewidth 633 nm DBR diode

    NASA Astrophysics Data System (ADS)

    Rerucha, Simon; Yacoot, Andrew; Pham, Tuan M.; Cizek, Martin; Hucl, Vaclav; Lazar, Josef; Cip, Ondrej

    2017-04-01

    We demonstrated that an iodine stabilized distributed Bragg reflector (DBR) diode based laser system lasing at a wavelength in close proximity to λ =633 nm could be used as an alternative laser source to the helium-neon lasers in both scientific and industrial metrology. This yields additional advantages besides the optical frequency stability and coherence: inherent traceability, wider optical frequency tuning range, higher output power and high frequency modulation capability. We experimentally investigated the characteristics of the laser source in two major steps: first using a wavelength meter referenced to a frequency comb controlled with a hydrogen maser and then on an interferometric optical bench testbed where we compared the performance of the laser system with that of a traditional frequency stabilized He–Ne laser. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology, especially in conjunction with novel interferometric detection methods exploiting high frequency modulation or multiaxis measurement systems.

  7. Investigations on the potential of a novel diode pumped Er:YAG laser system for dental applications

    NASA Astrophysics Data System (ADS)

    Stock, Karl; Hausladen, Florian; Hibst, Raimund

    2012-01-01

    The successful clinical application of the Er:YAG-laser in dentistry is well known, documented by numerous published studies. These lasers are flash lamp pumped systems and emit pulses of typically some 100 μs duration with energies of up to 1 J. Pulse repetition rates can reach up to 100Hz, and mean powers are up to about 8W. As an alternative to these laser systems recently a novel diode pumped Er:YAG laser system (Pantec Engineering AG) became available. This laser can provide a pulse repetition rate up to 2kHz and a mean laser power up to 15W. The aim of the presented study is to investigate the effect of this laser system on dental hard and soft tissue at various irradiation parameters, particular at repetition rates more than 100 Hz. At first an appropriate experimental set-up was realized with a beam delivery and focusing unit, a computer controlled stepper unit with sample holder, and a shutter unit. The stepper unit allows to move the samples (dentin or enamel slides of extracted human teeth, chicken breast, pig bone) with a defined velocity during irradiation by various laser parameters. For rinsing the sample surface a water spray was also included. The laser produced grooves and cuts were analyzed by light microscopy and laser scanning microscopy regarding to the ablation quality, geometry, ablation efficacy, and thermal effects. The grooves in dentin and enamel show a rough surface, typical for Er:YAG laser ablation. The craters are slightly cone shaped with sharp edges on the surface. Water cooling is essential to prevent thermal injury. The ablation efficacy in dentin is comparable to literature values of the flash lamp pumped Er:YAG laser. The cutting of bone and soft tissue is excellent and appears superior to earlier results obtained with flash lamp pumped system. As a further advantage, the broad range of repetition rates allows to widely vary the thermal side effects. In conclusion, these first experiments with a diode pumped Er:YAG laser

  8. Fixed-wavelength H2O absorption spectroscopy system enhanced by an on-board external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Brittelle, Mack S.; Simms, Jean M.; Sanders, Scott T.; Gord, James R.; Roy, Sukesh

    2016-03-01

    We describe a system designed to perform fixed-wavelength absorption spectroscopy of H2O vapor in practical combustion devices. The system includes seven wavelength-stabilized distributed feedback (WSDFB) lasers, each with a spectral accuracy of  ±1 MHz. An on-board external cavity diode laser (ECDL) that tunes 1320-1365 nm extends the capabilities of the system. Five system operation modes are described. In one mode, a sweep of the ECDL is used to monitor each WSDFB laser wavelength with an accuracy of  ±30 MHz. Demonstrations of fixed-wavelength thermometry at 10 kHz bandwidth in near-room-temperature gases are presented; one test reveals a temperature measurement error of ~0.43%.

  9. Intensity Scaling for Diode Pumped Alkali Lasers

    DTIC Science & Technology

    2012-01-01

    unphased diode lasers is absorbed in the near IR by atomic potassium, rubidium , or cesium. The gain cell for a DPAL system using a heat pipe design is...demonstrated linear scaling of a rubidium laser to 32 times threshold.3 In our present work, we explore scaling to pump in- tensities of >100kW/cm2. The...of output power. Each alkali atom in the laser medium may be required to cycle as many as 1010 pump photons per second. We demonstrated a rubidium

  10. Pulsed laser diode photoacoustic tomography (PLD-PAT) system for fast in vivo imaging of small animal brain

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Kalva, Sandeep Kumar; Moothanchery, Mohesh; Pramanik, Manojit

    2017-03-01

    In recent years, high-repetition rate pulsed laser diode (PLD) was used as an alternative to the Nd:YAG lasers for photoacoustic tomography (PAT). The use of PLD makes the overall PAT system, a low-cost, portable, and high frame rate imaging tool for preclinical applications. In this work, we will present a portable in vivo pulsed laser diode based photoacoustic tomography (PLD-PAT) system. The PLD is integrated inside a circular scanning geometry. The PLD can provide near-infrared ( 803 nm) pulses with pulse duration 136 ns, and pulse energy 1.4 mJ / pulse at 7 kHz repetition rate. The system will be demonstrated for in vivo fast imaging of small animal brain. To enhance the contrast of brain imaging, experiments will be carried out using contrast agents which have strong absorption around laser excitation wavelength. This low-cost, portable small animal brain imaging system could be very useful for brain tumor imaging and therapy.

  11. Diode Pumped Fiber Laser.

    DTIC Science & Technology

    1984-12-01

    molybdium oxide ( GMO ). The best diameter variations obtained so far are on the order of 1%. It is expected that these fibers should exhibit lower...that the absorbed pump power at threshold is given by "P:" hvp 6, 1Pth = (9) O-rf 21 J(0) where SJ 1(0) =J 1(0, 0, ) =ffj soI (x, y, z) ro(x, y, z) dv...epoxy, the argon laser bean ) was first aligned through a fiber at a low power level and then slowly increased. For preliminary tests the laser cavity

  12. Laser Systems

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Tunable diode lasers are employed as radiation sources in high resolution infrared spectroscopy to determine spectral characteristics of gaseous compounds. With other laser systems, they are produced by Spectra-Physics, and used to monitor chemical processes, monitor production of quantity halogen lamps, etc. The Laser Analytics Division of Spectra-Physics credits the system's reliability to a program funded by Langley in the 1970s. Company no longer U.S.-owned. 5/22/97

  13. Heterodyne applications of tunable semiconductor diode lasers

    NASA Technical Reports Server (NTRS)

    Sidney, B. D.

    1983-01-01

    Infrared tunable diode lasers were developed in the 1960s and have been a valuable radiation source for high resolution laboratory and in situ spectroscopy. Use of Pb-salt Tunable Diode Lasers (TDL) in heterodyne applications impose stringent requirements on the TDL not normally required for laboratory spectroscopy. A review will be made of progress associated with TDLs in such heterodyne applications. Areas addressed will include such items as lifetime, operating temperature, and factors affecting excess noise. The review will emphasize the experience at Langley Research Center, but will include material from other users. The Langley information will include a description and current status of the Laser Heterodyne Spectrometer experiment and atmospheric solar absorption data obtained from a groundbased heterodyne system.

  14. Self-Injection Locking Of Diode Lasers

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1991-01-01

    Simple optical coupling scheme locks array of gain-guided diode lasers into oscillation in single mode and with single-lobed output beam. Selective feedback from thin etalon self-injection-locks array into desired mode. One application of new scheme for pumping of neodymium: yttrium aluminum garnet lasers with diode-laser arrays.

  15. Self-Injection Locking Of Diode Lasers

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1991-01-01

    Simple optical coupling scheme locks array of gain-guided diode lasers into oscillation in single mode and with single-lobed output beam. Selective feedback from thin etalon self-injection-locks array into desired mode. One application of new scheme for pumping of neodymium: yttrium aluminum garnet lasers with diode-laser arrays.

  16. Diode pumped tunable dye laser

    NASA Astrophysics Data System (ADS)

    Burdukova, O.; Gorbunkov, M.; Petukhov, V.; Semenov, M.

    2017-03-01

    A wavelength-tunable dye laser pumped by blue laser diodes (λ =445 nm) in a 200 ns pulsed mode has been developed. We used a 3-mirror cavity with transverse excitation and total internal reflection of laser beam in the active element. Tuning curves for 8 dyes in benzyl alcohol were measured in the range of 506-700 nm. Four dyes have their tuning range more than 60 nm, which is comparable to the tuning ranges of other dye lasers pumped by more expensive sources. The output energy obtained at the generation maximum of both DCM and coumarin 540A dyes was approximately 130 nJ while the pump energy was 2400 nJ.

  17. Prototype laser-diode-pumped solid state laser transmitters

    NASA Technical Reports Server (NTRS)

    Kane, Thomas J.; Cheng, Emily A. P.; Wallace, Richard W.

    1989-01-01

    Monolithic, diode-pumped Nd:YAG ring lasers can provide diffraction-limited, single-frequency, narrow-linewidth, tunable output which is adequate for use as a local oscillator in a coherent communication system. A laser was built which had a linewidth of about 2 kHz, a power of 5 milliwatts, and which was tunable over a range of 30 MHz in a few microseconds. This laser was phase-locked to a second, similar laser. This demonstrates that the powerful technique of heterodyne detection is possible with a diode-pumped laser used as the local oscillator. Laser diode pumping of monolithic Nd:YAG rings can lead to output powers of hundreds of milliwatts from a single laser. A laser was built with a single-mode output of 310 mW. Several lasers can be chained together to sum their power, while maintaining diffraction-limited, single frequency operation. This technique was demonstrated with two lasers, with a total output of 340 mW, and is expected to be practical for up to about ten lasers. Thus with lasers of 310 mW, output of up to 3 W is possible. The chaining technique, if properly engineered, results in redundancy. The technique of resonant external modulation and doubling is designed to efficiently convert the continuous wave, infrared output of our lasers into low duty-cycle pulsed green output. This technique was verified through both computer modeling and experimentation. Further work would be necessary to develop a deliverable system using this technique.

  18. High-speed pre-clinical brain imaging using pulsed laser diode based photoacoustic tomography (PLD-PAT) system

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Pramanik, Manojit

    2016-03-01

    Photoacoustic tomography (PAT) is a promising biomedical imaging modality for small animal imaging, breast cancer imaging, monitoring of vascularisation, tumor angiogenesis, blood oxygenation, total haemoglobin concentration etc. The existing PAT systems that uses Q-switched Nd:YAG and OPO nanosecond lasers have limitations in clinical applications because they are expensive, non-potable and not suitable for real-time imaging due to their low pulse repetition rate. Low-energy pulsed near-infrared diode laser which are low-cost, compact, and light-weight (<200 grams), can be used as an alternate. In this work, we present a photoacoustic tomography system with a pulsed laser diode (PLD) that can nanosecond pulses with pulse energy 1.3 mJ/pulse at ~803 nm wavelength and 7000 Hz repetition rate. The PLD is integrated inside a single-detector circular scanning geometric system. To verify the high speed imaging capabilities of the PLD-PAT system, we performed in vivo experimental results on small animal brain imaging using this system. The proposed system is portable, low-cost and can provide real-time imaging.

  19. Diode Pumped Fiber Laser.

    DTIC Science & Technology

    1987-08-01

    mounting fixture beeame soft and gradually come out of the fixture. S)me chemical reaction was takin- place between the epoxy and the dye solvent , which...loose. The solvent apparenlly did no)t affect the bonding agent used to attach the fibers inside the capillarie,. \\lthmigh individual capillarv tubes...pure solvent . was added to the cavity laser oscillation ceased, and was onlv re, ,t()red after readjuisting the orientation of the output coupler, as

  20. Industrial applications of high power diode lasers in materials processing

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich

    2003-03-01

    Diode lasers are widely used in communication, computer and consumer electronics technology. These applications are based on systems, which provide power in the milliwatt range. However, in the mean time high power diode lasers have reached the kilowatt power range. This became possible by special cooling and mounting as well as beam combination and beam forming technologies. Such units are nowadays used as a direct source for materials processing. High power diode lasers have entered the industrial manufacturing area [Proceedings of the Advanced Laser Technologies Conference 2001, Proc. SPIE, Constanta, Romania, 11-14 September 2001].

  1. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  2. Advances in high power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  3. Excess noise in tunable diode lasers

    NASA Technical Reports Server (NTRS)

    Rowland, C. W.

    1981-01-01

    The method and the apparatus for identifying excess-noise regions in tunable diode lasers are described. These diode lasers exhibit regions of excess noise as their wavelength is tuned. If a tunable diode laser is to be used as a local oscillator in a superheterodyne optical receiver, these excess-noise regions severely degrade the performance of the receiver. Measurement results for several tunable diode lasers are given. These results indicate that excess noise is not necessarily associated with a particular wavelength, and that it is possible to select temperature and injection current such that the most ideal performance is achieved.

  4. Composite photopolymerization with diode laser.

    PubMed

    Knezevic, Alena; Ristic, Mira; Demoli, Nazif; Tarle, Zrinka; Music, Svetozar; Negovetic Mandic, Visnja

    2007-01-01

    Under clinical conditions, the time needed for the proper light curing of luting composites or the multi-incremental buildup of a large restoration with halogen curing units is quite extensive. Due to the development of high power curing devices, such as argon lasers and plasma arc lights and, in order to decrease curing time, halogen and LED devices have developed a high intensity polymerization mode. This study compared the degree of conversion using Fourier Transform Infrared Spectroscopy (FT-IR) of two composite materials: Tetric Ceram and Tetric EvoCeram polymerized with three polymerization modes (high, low and soft mode) of a Bluephase 16i LED curing unit and blue diode laser intensity of 50 mW on the output of the laser beam and 35 mW/cm2 on the resin composite sample. Descriptive statistic, t-test, ANOVA, Pearson Correlation and Tukey Post hoc tests were used for statistical analyses. The results show a higher degree of conversion for the polymerization of composite samples with all photopolymerization modes of the LED curing unit. However, there is no significant difference in the degree of conversion between the LED unit and 50-second polymerization with the blue diode laser. Tetric EvoCeram shows a lower degree of conversion regardless of the polymerization mode (or light source) used.

  5. Diode laser potential in laser cleaning of stones

    NASA Astrophysics Data System (ADS)

    Salimbeni, Renzo; Pini, Roberto; Siano, Salvatore; Bachmann, Friedrich G.; Meyer, Frank

    2001-10-01

    In this work we investigated for the first time the laser cleaning process of encrusted stones by employing a high power diode laser system. The test have been carried out using a Rofin-Sinar mod. DL025S emitting up to 2.5 kW CW power to clean various samples representing natural encrustation by pollution exposition and graffiti, typically encountered on historical monuments and buildings in urban environment.

  6. Long-path monitoring of atmospheric carbon monoxide with a tunable diode laser system.

    PubMed

    Ku, R T; Hinkley, E D; Sample, J O

    1975-04-01

    Long-path measurements of carbon monoxide in the atmosphere are described. The technique of resonance absorption was used in which the wavelength of radiation from a PbS(0.82)MbSe(0.18) semiconductor diode laser was tuned into coincidence with an absorption line of CO in its fundamental band around 4.7 microm. By employing rapid frequency modulation of the laser emission to overcome atmospheric turbulence effects, it was possible to achieve a minimum detectable concentration of 5 parts per billion over a 0.61-km path. Continuous around-the-clock monitoring was also performed and permitted increases in the ambient CO level due to commuter traffic to be observed.

  7. Digital control of diode laser for atmospheric spectroscopy

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Rutledge, C. W. (Inventor)

    1985-01-01

    A system is described for remote absorption spectroscopy of trace species using a diode laser tunable over a useful spectral region of 50 to 200 cm(-1) by control of diode laser temperature over range from 15 K to 100 K, and tunable over a smaller region of typically 0.1 to 10 cm(-1) by control of the diode laser current over a range from 0 to 2 amps. Diode laser temperature and current set points are transmitted to the instrument in digital form and stored in memory for retrieval under control of a microprocessor during measurements. The laser diode current is determined by a digital to analog converter through a field effect transistor for a high degree of ambient temperature stability, while the laser diode temperature is determined by set points entered into a digital to analog converter under control of the microprocessor. Temperature of the laser diode is sensed by a sensor diode to provide negative feedback to the temperature control circuit that responds to the temperature control digital to analog converter.

  8. Diode-Laser Phase Conjugation 03-FS-030 Final Report

    SciTech Connect

    Page, R H; Beach, R J; Payne, S A; Holzrichter, J F

    2005-02-14

    Arrays of lasers are often considered when a need exists to increase laser optical output power, for a variety of purposes. Similarly, individual semiconductor laser-diodes, generating 0.01-1.0 W each, are commonly placed in arrays in order to increase total optical power onto targeted objects. Examples of such usage are diode-laser pump arrays for solid-slab heat-capacity lasers, laser arrays for heat-treating materials, and arrays for efficient solid state laser systems. The commercial and defense communities also use such arrays for many applications from laser range-finders, laser designators, to laser machining systems, etc. However, the arraying process does not automatically increase ''focusable'' light on target (i.e., intensity/steradian). For those applications requiring the highest focusability, it is necessary that the collective output beam from arrays of individual lasers be phase-coherent. Under this condition, the individual laser-element optical outputs are ''fused together'' into a larger area, phase coherent (i.e., all wavefronts are ''in step''), high-power combined beam. The process of joining multiple laser beams together to produce a single coherent wave, is in general very difficult and seldom accomplished. Thus joining together many hundreds to thousands of beams from individual laser-diodes, in large arrays, is still an unsolved problem. There are 2 major reasons for this. Firstly, the phase of each output laser beam (i.e. the wave-fronts) from each laser diode often fluctuates within nanosecond time periods, making a control loop with sufficient bandwidth difficult to build. In fact, phase fluctuations (related to laser linewidth) limit the size of an extended system of arrayed diodes because of speed-of-light restrictions on information flow. Secondly, the output power per prior laser diode has been low ( < 1W,) so that the size, expense, and complexity of control systems for correcting a multitude of output phases of the individual

  9. Laser welding of polymers using high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2002-06-01

    Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore, this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented result concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the sue laser system the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.

  10. Laser welding of polymers using high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2003-09-01

    Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented results concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the used laser systems the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.

  11. Laser diode array pumped continuous wave Rubidium vapor laser.

    PubMed

    Zhdanov, B V; Stooke, A; Boyadjian, G; Voci, A; Knize, R J

    2008-01-21

    We have demonstrated continuous wave operation of a laser diode array pumped Rb laser with an output power of 8 Watts. A slope efficiency of 60% and a total optical efficiency of 45% were obtained with a pump power of 18 Watts. This laser can be scaled to higher powers by using multiple laser diode arrays or stacks of arrays.

  12. Rubidium vapor laser pumped by two laser diode arrays.

    PubMed

    Zhdanov, Boris V; Stooke, Adam; Boyadjian, Gregory; Voci, Adam; Knize, R J

    2008-03-01

    Scaling of alkali lasers to higher powers requires using multiple diode lasers for pumping. The first (to our knowledge) results of a cw rubidium laser pumped by two laser diode arrays are presented. A slope efficiency of 53%, total optical efficiency of 46%, and output power of 17 W have been demonstrated.

  13. A near-infrared methane detection system using a 1.654 μm wavelength-modulated diode laser

    NASA Astrophysics Data System (ADS)

    Fu, Yang; Liu, Hui-fang; Sui, Yue; Li, Bin; Ye, Wei-lin; Zheng, Chuan-tao; Wang, Yi-ding

    2016-03-01

    By adopting a distributed feedback laser (DFBL) centered at 1.654 μm, a near-infrared (NIR) methane (CH4) detection system based on tunable diode laser absorption spectroscopy (TDLAS) is experimentally demonstrated. A laser temperature control as well as wavelength modulation module is developed to control the laser's operation temperature. The laser's temperature fluctuation can be limited within the range of -0.02—0.02 °C, and the laser's emitting wavelength varies linearly with the temperature and injection current. An open reflective gas sensing probe is realized to double the absorption optical path length from 0.2 m to 0.4 m. Within the detection range of 0—0.01, gas detection experiments were conducted to derive the relation between harmonic amplitude and gas concentration. Based on the Allan deviation at an integral time of 1 s, the limit of detection ( LoD) is decided to be 2.952×10-5 with a path length of 0.4 m, indicating a minimum detectable column density of ~1.2×10-5 m. Compared with our previously reported NIR CH4 detection system, this system exhibits some improvement in both optical and electrical structures, including the analogue temperature controller with less software consumption, simple and reliable open reflective sensing probe.

  14. Laser hazard analysis for various candidate diode lasers associated with the high resolution pulsed scanner.

    SciTech Connect

    Augustoni, Arnold L.

    2004-10-01

    A laser hazard analysis and safety assessment was performed for each various laser diode candidates associated with the High Resolution Pulse Scanner based on the ANSI Standard Z136.1-2000, American National Standard for the Safe Use of Lasers. A theoretical laser hazard analysis model for this system was derived and an Excel{reg_sign} spreadsheet model was developed to answer the 'what if questions' associated with the various modes of operations for the various candidate diode lasers.

  15. Laser diode package with enhanced cooling

    DOEpatents

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

    2012-06-12

    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.

  16. Laser diode package with enhanced cooling

    DOEpatents

    Deri, Robert J; Kotovsky, Jack; Spadaccini, Christopher M

    2012-06-26

    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.

  17. Laser diode package with enhanced cooling

    DOEpatents

    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.

  18. Hermetic diode laser transmitter module

    NASA Astrophysics Data System (ADS)

    Ollila, Jyrki; Kautio, Kari; Vahakangas, Jouko; Hannula, Tapio; Kopola, Harri K.; Oikarinen, Jorma; Sivonen, Matti

    1999-04-01

    In very demanding optoelectronic sensor applications it is necessary to encapsulate semiconductor components hermetically in metal housings to ensure reliable operation of the sensor. In this paper we report on the development work to package a laser diode transmitter module for a time- off-light distance sensor application. The module consists of a lens, laser diode, electronic circuit and optomechanics. Specifications include high acceleration, -40....+75 degree(s)C temperature range, very low gas leakage and mass-production capability. We have applied solder glasses for sealing optical lenses and electrical leads hermetically into a metal case. The lens-metal case sealing has been made by using a special soldering glass preform preserving the optical quality of the lens. The metal housings are finally sealed in an inert atmosphere by welding. The assembly concept to retain excellent optical power and tight optical axis alignment specifications is described. The reliability of the laser modules manufactured has been extensively tested using different aging and environmental test procedures. Sealed packages achieve MIL- 883 standard requirements for gas leakage.

  19. Diode Lasers and Practical Trace Analysis.

    ERIC Educational Resources Information Center

    Imasaka, Totaro; Nobuhiko, Ishibashi

    1990-01-01

    Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

  20. Diode Lasers and Practical Trace Analysis.

    ERIC Educational Resources Information Center

    Imasaka, Totaro; Nobuhiko, Ishibashi

    1990-01-01

    Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

  1. Investigation of Diode Pumped Alkali Laser atmospheric transmission using tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Rice, Christopher A.

    A field deployable ruggedized tunable diode laser absorption spectroscopy (TDLAS) device fiber coupled to a pair of 12.5" Ritchey-Chretien telescopes was used to study atmospheric propagation for open path lengths of 100 to 1,000 meters to estimate atmospheric transmission at key High Energy Laser (HEL) wavelengths. The potassium (K) version of the Diode Pumped Alkali Laser (DPAL) operates in between two of the sharp oxygen rotational features in the PP and the PQ branches. The device can be used to observe rotational temperature, concentrations, and atmospheric pressure. Molecular oxygen absorption lines near the potassium, and water vapor absorption lines near the rubidium and cesium DPALs at wavelengths near 770 nm, 795 nm, and 895 nm, respectively, were investigated using the Line-by-Line Radiative Transfer Model (LBLRTM) with the High Energy Laser End-to-End Simulation (HELEEOS). A tunable diode laser absorption spectroscopy (TDLAS) device was used to anchor simulations to actual outdoor atmospheric open-path collections. The implications of different laser gain cell configurations in DPAL systems are discussed, including spectral lineshape and atmospheric transmittance and are compared to existing high power laser systems.

  2. Portable Diode Pumped Femtosecond Lasers

    DTIC Science & Technology

    2007-03-01

    Troshin, V. G. Shcherbitsky, N. V. Kuleshov, V. N. Matrosov , T. A. Matrosava, M. I. Kupchenko, F. Brunner, R. Paschotta, F. Morier-Genoud, and U. Keller...Tolstik, V. G. Shcherbitsky, N. V. Kuleshov, V. N. Matrosov , T. A. Matrosava, and M. I. Kupchenko. “Spectroscopy and continuous-wave diode-pumped laser...Denisov, A. E. Troshin, K. V. Yumashev, N. V. Kuleshov, V. N. Matrosov , T. A. Matrosova, and M. I. Kupchenko. “Yb3+-doped YVO4 crystal for efficient

  3. Optical communication with semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, X.

    1989-01-01

    This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response from the APD/preamplifier module were also measured.

  4. A Theoretical Model Analysis of Absorption of a Three level Diode Pumped Alkali Laser

    DTIC Science & Technology

    2009-03-01

    A THEORETICAL MODEL ANALYSIS OF ABSORPTION OF A THREE LEVEL DIODE PUMPED ALKALI LASER ...States Government. AFIT/GAP/ENP/09-M07 A THEORETICAL MODEL ANALYSIS OF ABSORPTION OF A THREE LEVEL DIODE PUMPED ALKALI LASER THESIS...This paper models the absorption phenomena of light in a three level diode pumped alkali laser system. Specifically this model calculates for a user

  5. Compact, robust, and spectrally pure diode-laser system with a filtered output and a tunable copy for absolute referencing

    NASA Astrophysics Data System (ADS)

    Kirilov, E.; Mark, M. J.; Segl, M.; Nägerl, H.-C.

    2015-05-01

    We report on a design of a compact laser system composed of an extended-cavity diode laser with high passive stability and a pre-filter Fabry-Perot cavity. The laser is frequency-stabilized relative to the cavity using a serrodyne technique with a correction bandwidth of ≥6 MHz and a dynamic range of ≥700 MHz. The free-running laser system has a power spectral density (PSD) ≤100 Hz2/Hz centered mainly in the acoustic frequency range. A highly tunable, 0.5-1.3 GHz copy of the spectrally pure output beam is provided, which can be used for further stabilization of the laser system to an ultra-stable reference. We demonstrate a simple one-channel lock to such a reference that brings down the PSD to the sub-Hz level. The tuning, frequency stabilization, and sideband imprinting are achieved by a minimum number of key elements comprising a fibered electro-optic modulator, acousto-optic modulator, and a nonlinear transmission line. The system is easy to operate, scalable, and highly applicable to atomic/molecular experiments demanding high spectral purity, long-term stability, and robustness.

  6. Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System —An in vitro study

    PubMed Central

    Asnaashari, Mohamad; Ebad, Leila Tahmasebi

    2016-01-01

    Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load. PMID:27853346

  7. Comparison of Antibacterial Effects of 810 and 980- nanometer Diode Lasers on Enterococcus Faecalis in the Root Canal System -An in vitro study.

    PubMed

    Asnaashari, Mohamad; Ebad, Leila Tahmasebi; Shojaeian, Shiva

    2016-10-01

    Background and aim: Use of laser technology in endodontics has greatly increased in the recent years due to the introduction of new wavelengths and methods and optimal antimicrobial and smear layer removal properties of lasers. This in vitro study aimed to compare the antibacterial effects of diode lasers of 810 nm and 980 nm wavelength on Enterococcus faecalis (E. faecalis) biofilm in the root canal system. Materials and methods: Fifty single-canal human anterior teeth were cleaned, shaped, sterilized and randomly divided into four groups namely two experimental, one positive and one negative control group. The experimental and positive control groups were inoculated with E. faecalis and incubated for two weeks. The experimental group one (n=20) received 810 nm diode laser irradiation (1.5W) while the experimental group two (n=20) was subjected to 980 nm diode laser irradiation (1.5W). The E. faecalis colony forming units (CFUs) were counted in each root canal before and after laser irradiation. Results: Laser irradiation significantly decreased the bacterial colony count in both experimental groups. The reduction in microbial count was significantly greater in 810 nm laser group compared to 980 nm laser group. Conclusion: Irradiation of both 810 and 980 nm lasers significantly decreased the E. faecalis count in the root canal system; 810 nm laser was more effective in decreasing the intracanal microbial load.

  8. Diode Laser Ear Piercing: A Novel Technique

    PubMed Central

    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. PMID:28163460

  9. Diode Laser Ear Piercing: A Novel Technique.

    PubMed

    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.

  10. Modular package for cooling a laser diode array

    DOEpatents

    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.

  11. Smart medical diode lasers: fantasy becoming reality

    NASA Astrophysics Data System (ADS)

    Soltz, Barbara A.

    1995-05-01

    Design principles and rules are currently being formulated for building intelligent machines for `factories of the future'. The intelligent machine is one which has control functions that resemble the `brain', `eyes' and other anthropomorphic substitutes for the skilled expert. These skills are related to the expert's knowledge and abilities to plan complex actions and to detect errors with a continual upgrade of machine understanding. A craft related language enables a high level of communication between the system and the operator. These same capabilities can be embodied in a medical laser system. This paper will define the key characteristics of a smart medical laser and will describe the advantages of an intelligent system based on diode laser technology. System control functions and software architecture will be explained and the main subsystems highlighted.

  12. Phase shifting and phase retrieval with a fully automated laser diode system.

    PubMed

    Rivera-Ortega, Uriel; Dirckx, Joris; Meneses-Fabian, Cruz

    2015-11-20

    A low-cost and fully automated process for phase-shifting interferometry (PSI) by continuously changing the input voltage of a laser diode (LD) under the scheme of an unbalanced Twyman-Green interferometer (TGI) setup is presented. The input signal of a LD is controlled by a data acquisition (NI-DAQ) device that allows it to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. The phase map is obtained using the Carré algorithm. Measurements of visibility and phase shift to verify the PSI requirements are shown. It is demonstrated with experimental results and statistical analysis that the phase retrieval can be successfully achieved without calibration and using minimal optical devices.

  13. Diode lasers: From laboratory to industry

    NASA Astrophysics Data System (ADS)

    Nasim, Hira; Jamil, Yasir

    2014-03-01

    The invention of first laser in 1960 triggered the discovery of several new families of lasers. A rich interplay of different lasing materials resulted in a far better understanding of the phenomena particularly linked with atomic and molecular spectroscopy. Diode lasers have gone through tremendous developments on the forefront of applied physics that have shown novel ways to the researchers. Some interesting attributes of the diode lasers like cost effectiveness, miniature size, high reliability and relative simplicity of use make them good candidates for utilization in various practical applications. Diode lasers are being used by a variety of professionals and in several spectroscopic techniques covering many areas of pure and applied sciences. Diode lasers have revolutionized many fields like optical communication industry, medical science, trace gas monitoring, studies related to biology, analytical chemistry including elemental analysis, war fare studies etc. In this paper the diode laser based technologies and measurement techniques ranging from laboratory research to automated field and industry have been reviewed. The application specific developments of diode lasers and various methods of their utilization particularly during the last decade are discussed comprehensively. A detailed snapshot of the current state of the art diode laser applications is given along with a detailed discussion on the upcoming challenges.

  14. Multiple-Diode-Laser Gas-Detection Spectrometer

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Beer, Reinhard; Sander, Stanley P.

    1988-01-01

    Small concentrations of selected gases measured automatically. Proposed multiple-laser-diode spectrometer part of system for measuring automatically concentrations of selected gases at part-per-billion level. Array of laser/photodetector pairs measure infrared absorption spectrum of atmosphere along probing laser beams. Adaptable to terrestrial uses as monitoring pollution or control of industrial processes.

  15. Multiple-Diode-Laser Gas-Detection Spectrometer

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Beer, Reinhard; Sander, Stanley P.

    1988-01-01

    Small concentrations of selected gases measured automatically. Proposed multiple-laser-diode spectrometer part of system for measuring automatically concentrations of selected gases at part-per-billion level. Array of laser/photodetector pairs measure infrared absorption spectrum of atmosphere along probing laser beams. Adaptable to terrestrial uses as monitoring pollution or control of industrial processes.

  16. Frequency stabilization of diode-laser-pumped solid state lasers

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1988-01-01

    The goal of the NASA Sunlite program is to fly two diode-laser-pumped solid-state lasers on the space shuttle and while doing so to perform a measurement of their frequency stability and temporal coherence. These measurements will be made by combining the outputs of the two lasers on an optical radiation detector and spectrally analyzing the beat note. Diode-laser-pumped solid-state lasers have several characteristics that will make them useful in space borne experiments. First, this laser has high electrical efficiency. Second, it is of a technology that enables scaling to higher powers in the future. Third, the laser can be made extremely reliable, which is crucial for many space based applications. Fourth, they are frequency and amplitude stable and have high temporal coherence. Diode-laser-pumped solid-state lasers are inherently efficient. Recent results have shown 59 percent slope efficiency for a diode-laser-pumped solid-state laser. As for reliability, the laser proposed should be capable of continuous operation. This is possible because the diode lasers can be remote from the solid state gain medium by coupling through optical fibers. Diode lasers are constructed with optical detectors for monitoring their output power built into their mounting case. A computer can actively monitor the output of each diode laser. If it sees any variation in the output power that might indicate a problem, the computer can turn off that diode laser and turn on a backup diode laser. As for stability requirements, it is now generally believed that any laser can be stabilized if the laser has a frequency actuator capable of tuning the laser frequency as far as it is likely to drift in a measurement time.

  17. An external cavity diode laser using a volume holographic grating

    NASA Astrophysics Data System (ADS)

    Chuang, Ho-Chiao; Chang, Chang-Ray; Chen, Chun-Chia; Chang, Ming-Shien

    2012-10-01

    This study presents an external cavity diode laser (ECDL) system, utilizing a volume holographic grating (VHG) and a microfabricated silicon flexure as the VHG holder. The laser design is aimed for easy assembly, controllability, and better stability of the laser cavity. The laser frequency was stabilized to a D2 transition of rubidium at 780.247 nm, with a mode-hop-free tuning range of 16 GHz and 9.6 GHz with and without feed-forward on the diode injection current. The measured linewidth was 850 kHz in 500 s, qualified for laser cooling experiments.

  18. Improved Thermoelectrically Cooled Laser-Diode Assemblies

    NASA Technical Reports Server (NTRS)

    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.

  19. Improved Thermoelectrically Cooled Laser-Diode Assemblies

    NASA Technical Reports Server (NTRS)

    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.

  20. Transversely diode-pumped alkali metal vapour laser

    SciTech Connect

    Parkhomenko, A I; Shalagin, A M

    2015-09-30

    We have studied theoretically the operation of a transversely diode-pumped alkali metal vapour laser. For the case of high-intensity laser radiation, we have obtained an analytical solution to a complex system of differential equations describing the laser. This solution allows one to exhaustively determine all the energy characteristics of the laser and to find optimal parameters of the working medium and pump radiation (temperature, buffer gas pressure, and intensity and width of the pump spectrum). (lasers)

  1. Scaling brilliance of high power laser diodes

    NASA Astrophysics Data System (ADS)

    König, Harald; Grönninger, Guenther; Lauer, Christian; Reill, Wolfgang; Arzberger, Markus; Strauß, Uwe; Kissel, Heiko; Biesenbach, Jens; Kösters, Arnd; Malchus, Joerg; Krause, Volker K.

    2010-02-01

    New direct diode laser systems and fiber lasers require brilliant fiber coupled laser diodes for efficient operation. In the German funded project HEMILAS different laser bar designs are investigated with tailored beam parameter products adapted for efficient fiber coupling. In this paper we demonstrate results on 9xx and 1020nm bars suitable for coupling into 200μm fibers. With special facet technology and optimised epitaxial structure COD-free laser bars were fabricated with maximum efficiency above 66%. For short bars consisting of five 100μm wide emitters 75W CW maximum output power was reached. In QCW-mode up to 140W are demonstrated. The 10% fill factor bars with 4mm cavity are mounted with hard solder. Lifetime tests in long pulse mode with 35W output power exceed 5000 hours of testing without degradation or spontaneous failures. Slow axis divergence stays below 7° up to power levels of 40W and is suitable for simple fiber coupling into 200μm NA 0.22 fibers with SAC and FAC lenses. For fiber coupling based on beam rearrangement with step mirrors, bars with higher fill factor of 50% were fabricated and tested. The 4mm cavity short bars reach efficiencies above 60%. Lifetime tests at accelerated powers were performed. Finally fiber coupling results with output powers of up to 2.4 kW and beam quality of 30 mm mrad are demonstrated.

  2. Flight demonstration of laser diode initiated ordnance

    NASA Technical Reports Server (NTRS)

    Boucher, Craig J.; Schulze, Norman R.

    1995-01-01

    A program has been initiated by NASA Headquarters to validate laser initiated ordnance in flight applications. The primary program goal is to bring together a team of government and industry members to develop a laser initiated ordnance system having the test and analysis pedigree to be flown on launch vehicles. The culmination of this effort was a flight of the Pegasus launch vehicle which had two fin rockets initiated by this laser system. In addition, a laser initiated ordnance squib was fired into a pressure bomb during thrusting flight. The complete ordnance system comprising a laser diode firing unit, fiber optic cable assembly, laser initiated detonator, and laser initiated squib was designed and built by The Ensign Bickford Company. The hardware was tested to the requirements of the Pegasus launch vehicle and integrated into the vehicle by The Ensign Bickford Company and the Orbital Sciences Corporation. Discussions include initial program concept, contract implementation, team member responsibilities, analysis results, vehicle integration, safing architecture, ordnance interfaces, mission timeline and telemetry data. A complete system description, summary of the analyses, the qualification test results, and the results of flight are included.

  3. Diode-pumped laser altimeter

    NASA Technical Reports Server (NTRS)

    Welford, D.; Isyanova, Y.

    1993-01-01

    TEM(sub 00)-mode output energies up to 22.5 mJ with 23 percent slope efficiencies were generated at 1.064 microns in a diode-laser pumped Nd:YAG laser using a transverse-pumping geometry. 1.32-micron performance was equally impressive at 10.2 mJ output energy with 15 percent slope efficiency. The same pumping geometry was successfully carried forward to several complex Q-switched laser resonator designs with no noticeable degradation of beam quality. Output beam profiles were consistently shown to have greater than 90 percent correlation with the ideal TEM(sub 00)-order Gaussian profile. A comparison study on pulse-reflection-mode (PRM), pulse-transmission-mode (PTM), and passive Q-switching techniques was undertaken. The PRM Q-switched laser generated 8.3 mJ pulses with durations as short as 10 ns. The PTM Q-switch laser generated 5 mJ pulses with durations as short as 5 ns. The passively Q-switched laser generated 5 mJ pulses with durations as short as 2.4 ns. Frequency doubling of both 1.064 microns and 1.32 microns with conversion efficiencies of 56 percent in lithium triborate and 10 percent in rubidium titanyl arsenate, respectively, was shown. Sum-frequency generation of the 1.064 microns and 1.32 microns radiations was demonstrated in KTP to generate 1.1 mJ of 0.589 micron output with 11.5 percent conversion efficiency.

  4. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

    1991-02-19

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

  5. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1991-01-01

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

  6. High-power passive-cooled diode laser device

    NASA Astrophysics Data System (ADS)

    Bonati, Guido F.; Hennig, Petra; Rollig, Ullrich; Lorenzen, Dirk

    2003-06-01

    In order to achieve a thermally stable diode laser system based on high power diode laser bars, actively cooled heatsinks in form of micro channel heat sinks (MCHS) are used to face the power loss density of 106 W/m2 while requiring a minimum device volume. At identical junction temperature, passively cooled diode lasers are usually lower in power and the device volume is much higher due to the heat flux spreading design of passive heatsinks. However, as a matter of principle, the cooling with MCHS sinks requires a sealing between the heat sink itself and the system around. This sealing is usually achieved by o-rings, what can never avoid the transfer of vapor from the cooling system into the vicinity of the diode laser. Extreme requirements on availability, which lead to corresponding lifetime requirements, like in telecom applications, already require passively cooled diode lasers without any water in the inner system boundaries. For applications not requiring the extreme compact design volume of actively cooled diode lasers but requiring extreme lifetime or a minimum outlay on the periphery, we started looking into passively cooled diode laser stacks. To achieve a minimized temperature rise in the junction, we already developed a new copper-based heat sink, spreading the power loss in an optimized manner. Based on this heatsink, we started developing a heat exchanger with a low thermal resistance while keeping the water out of the inner system boundaries. The thermal resistance is low enough to run up to 12 passively cooled diode lasers on a low ambient temperature with a minimum of periphery requirements.

  7. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    SciTech Connect

    Deri, R J

    2011-01-03

    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 {approx} 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

  8. Laser diodes for sensing applications: adaptive cruise control and more

    NASA Astrophysics Data System (ADS)

    Heerlein, Joerg; Morgott, Stefan; Ferstl, Christian

    2005-02-01

    Adaptive Cruise Controls (ACC) and pre-crash sensors require an intelligent eye which can recognize traffic situations and deliver a 3-dimensional view. Both microwave RADAR and "Light RADAR" (LIDAR) systems are well suited as sensors. In order to utilize the advantages of LIDARs -- such as lower cost, simpler assembly and high reliability -- the key component, the laser diode, is of primary importance. Here, we present laser diodes which meet the requirements of the automotive industry.

  9. A compact high brilliance diode laser

    NASA Astrophysics Data System (ADS)

    Bammer, F.; Holzinger, B.

    2006-02-01

    We explain some technical details regarding time-multiplexing of laser diodes, a method to improve the beam quality of diode lasers, which is still insufficient for many applications. Several pulsed laser diode beams are guided onto a common optical path to superpose the power of the laser diodes while maintaining the beam parameter product of a single laser diode. Pulsed operation of continuous wave laser diodes with average power equal to the specified cw-power of 4 W was tested for 150 hours without failure. We use a fast digital optical multiplexer built up by a cascade of binary optical switches. For the latter we use a Pockel's cell followed by a polarization filter, which allows addressing of two optical paths. Instead of direct on/off-switching we drive the crystals with a harmonic voltage course to avoid ringing caused by piezo-electricity. Up to now an optical power of 10.5 W was generated, 13 W are expected with some improvements. Furthermore we discuss the use of new 8 W laser diodes and the involved implications on driver technology.

  10. Applications of microlens-conditioned laser diode arrays

    SciTech Connect

    Beach, R.J.; Emanuel, M.A.; Freitas, B.L.

    1995-01-01

    The ability to condition the radiance of laser diodes using shaped-fiber cylindrical-microlens technology has dramatically increased the number of applications that can be practically engaged by diode laser arrays. Lawrence Livermore National Laboratory (LLNL) has actively pursued optical efficiency and engineering improvements in this technology in an effort to supply large radiance-conditioned laser diode array sources for its own internal programs. This effort has centered on the development of a modular integrated laser diode packaging technology with the goal of enabling the simple and flexible construction of high average power, high density, two-dimensional arrays with integrated cylindrical microlenses. Within LLNL, the principal applications of microlens-conditioned laser diode arrays are as high intensity pump sources for diode pumped solid state lasers (DPSSLs). A simple end-pumping architecture has been developed and demonstrated that allows the radiation from microlens-conditioned, two-dimensional diode array apertures to be efficiently delivered to the end of rod lasers. To date, pump powers as high as 2.5 kW have been delivered to 3 mm diameter laser rods. Such high power levels are critical for pumping solid state lasers in which the terminal laser level is a Stark level lying in the ground state manifold. Previously, such systems have often required operation of the solid state gain medium at low temperature to freeze out the terminal laser Stark level population. The authors recently developed high intensity pump sources overcome this difficulty by effectively pumping to much higher inversion levels, allowing efficient operation at or near room temperature. Because the end-pumping technology is scalable in absolute power, the number of rare-earth ions and transitions that can be effectively accessed for use in practical DPSSL systems has grown tremendously.

  11. Underwater Chaotic Lidar using Blue Laser Diodes

    NASA Astrophysics Data System (ADS)

    Rumbaugh, Luke K.

    The thesis proposes and explores an underwater lidar system architecture based on chaotic modulation of recently introduced, commercially available, low cost blue laser diodes. This approach is experimentally shown to allow accurate underwater impulse response measurements while eliminating the need for several major components typically found in high-performance underwater lidar systems. The proposed approach is to: 1. Generate wideband, noise-like intensity modulation signals using optical chaotic modulation of blue-green laser diodes, and then 2. Use this signal source to develop an underwater chaotic lidar system that uses no electrical signal generator, no electro-optic modulator, no optical frequency doubler, and no large-aperture photodetector. The outcome of this thesis is the demonstration of a new underwater lidar system architecture that could allow high resolution ranging, imaging, and water profiling measurements in turbid water, at a reduced size, weight, power and cost relative to state-of-the-art high-performance underwater lidar sensors. This work also makes contributions to the state of the art in optics, nonlinear dynamics, and underwater sensing by demonstrating for the first time: 1. Wideband noise-like intensity modulation of a blue laser diode using no electrical signal generator or electro-optic modulator. Optical chaotic modulation of a 462 nm blue InGaN laser diode by self-feedback is explored for the first time. The usefulness of the signal to chaotic lidar is evaluated in terms of bandwidth, modulation depth, and autocorrelation peak-to-sidelobe-ratio (PSLR) using both computer and laboratory experiments. In laboratory experiments, the optical feedback technique is shown to be effective in generating wideband, noise-like chaotic signals with strong modulation depth when the diode is operated in an external-cavity dominated state. The modulation signal strength is shown to be limited by the onset of lasing within the diode's internal

  12. Performance characterization of low-cost, high-speed, portable pulsed laser diode photoacoustic tomography (PLD-PAT) system.

    PubMed

    Upputuri, Paul Kumar; Pramanik, Manojit

    2015-10-01

    Photoacoustic tomography systems that uses Q-switched Nd:YAG/OPO pulsed lasers are expensive, bulky, and hence limits its use in clinical applications. The low pulse repetition rate of these lasers makes it unsuitable for real-time imaging when used with single-element ultrasound detector. In this work, we present a pulsed laser diode photoacoustic tomography (PLD-PAT) system that integrates a compact PLD inside a single-detector circular scanning geometry. We compared its performance against the traditional Nd:YAG/OPO based PAT system in terms of imaging depth, resolution, imaging time etc. The PLD provides near-infrared pulses at ~803 nm wavelength with pulse energy ~1.4 mJ/pulse at 7 kHz repetition rate. The PLD-PAT system is capable of providing 2D image in scan time as small as 3 sec with a signal-to-noise ratio ~30. High-speed and deep-tissue imaging is demonstrated on phantoms and biological samples. The PLD-PAT system is inexpensive, portable, allows high-speed PAT imaging, and its performance is as good as traditional expensive OPO based PAT system. Therefore, it holds promises for future translational biomedical imaging applications.

  13. Percutaneous diode laser disc nucleoplasty

    NASA Astrophysics Data System (ADS)

    Menchetti, P. P.; Longo, Leonardo

    2004-09-01

    The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.

  14. High efficiency >26 W diode end-pumped Alexandrite laser.

    PubMed

    Teppitaksak, Achaya; Minassian, Ara; Thomas, Gabrielle M; Damzen, Michael J

    2014-06-30

    We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

  15. Bright diode laser light source.

    PubMed

    Lassila, Erkki; Hernberg, Rolf

    2006-05-20

    A simplified multiwavelength prototype of an axially symmetric diode laser device based on stacks made of single emitters has been made, and the performance of the device has been demonstrated experimentally. The results verify that kilowatt-level light power can be focused into a circular spot with a 1/e2 diameter of 360 microm, a focal length of 100 mm, and a numerical aperture of 0.24, thus producing an average power density in excess of 10 kW/mm2 and a brightness of 6x10(10) W m-2 sr-1. The experiments also predict that it will be possible to increase these values to more than 60 kW/mm2 and 3x10(11) W m-2 sr-1.

  16. High power diode lasers reliability experiment

    NASA Astrophysics Data System (ADS)

    Lu, Guoguang; Xie, Shaofeng; Hao, Mingming; Huang, Yun; En, Yunfei

    2013-12-01

    In order to evaluate and obtain the actual lifetime data of high power laser diodes, an automated high power laser diodes reliability experiment was developed and reported in this paper. This computer controlled setup operates the laser diodes 24 hours a day, the parameters such as output power, wavelength were test once in one hour. The experiment has 60 work stations, the temperature control range is from 25°C to 70°C, and the output power of the aging device is beyond 20W.

  17. High power coherent polarization locked laser diode.

    PubMed

    Purnawirman; Phua, P B

    2011-03-14

    We have coherently combined a broad area laser diode array to obtain high power single-lobed output by using coherent polarization locking. The single-lobed coherent beam is achieved by spatially combining four diode emitters using walk-off crystals and waveplates while their phases are passively locked via polarization discrimination. While our previous work focused on coherent polarization locking of diode in Gaussian beams, we demonstrate in this paper, the feasibility of the same polarization discrimination for locking multimode beams from broad area diode lasers. The resonator is designed to mitigate the loss from smile effect by using retro-reflection feedback in the cavity. In a 980 nm diode array, we produced 7.2 W coherent output with M2 of 1.5x11.5. The brightness of the diode is improved by more than an order of magnitude.

  18. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  19. Continuous wave Cs diode pumped alkali laser pumped by single emitter narrowband laser diode.

    PubMed

    Zhdanov, B V; Venus, G; Smirnov, V; Glebov, L; Knize, R J

    2015-08-01

    This paper presents results of cooperative efforts on development of a continuous wave Cs diode pumped alkali laser with moderate output power, which can be considered as a prototype of the commercial device. The developed system operates at 895 nm with output power about 4 W and slope efficiency 28%. Measured turn on time of this system from the standby mode is about a minute.

  20. Arbitrary waveform generator to improve laser diode driver performance

    SciTech Connect

    Fulkerson, Jr, Edward Steven

    2015-11-03

    An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.

  1. Pump Diode Characterization for an Unstable Diode-Pumped Alkali Laser Resonator

    DTIC Science & Technology

    2013-03-01

    PUMP DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER RESONATOR THESIS Chad T. Taguba, Master Sergeant, USAF AFIT-ENP-13-M-33...not subject to copyright protection in the United States. AFIT-ENP-13-M-33 PUMP DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER ... DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER RESONATOR Approved: Chad T. Taguba, BS Master Sergeant, USAF

  2. Commercial applications of high-powered laser diodes

    NASA Astrophysics Data System (ADS)

    Cunningham, David L.; Jacobs, Richard D.

    1995-04-01

    The development of high power laser diodes using surface emitting distributed feedback (SEDFB) techniques has matured to the point where serious marketing analyses have been conducted. While development of the base technology continues, the initiation of systems applications and manufacturing engineering has begun. This effort, in direct response to growing market demand, is the critical bridge between research and the development of viable products for commercial applications. This paper addresses the history of laser technology development, the current status of high powered laser diode development, the forces defining current and future markets and the role of `conventional wisdom' in laser technology and market development.

  3. Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

    NASA Technical Reports Server (NTRS)

    Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

    1998-01-01

    This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

  4. Diode lasers for interstitial laser coagulation of the prostate

    NASA Astrophysics Data System (ADS)

    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.

  5. Reliability of high power laser diodes with external optical feedback

    NASA Astrophysics Data System (ADS)

    Bonsendorf, Dennis; Schneider, Stephan; Meinschien, Jens; Tomm, Jens W.

    2016-03-01

    Direct diode laser systems gain importance in the fields of material processing and solid-state laser pumping. With increased output power, also the influence of strong optical feedback has to be considered. Uncontrolled optical feedback is known for its spectral and power fluctuation effects, as well as potential emitter damage. We found that even intended feedback by use of volume Bragg gratings (VBG) for spectral stabilization may result in emitter lifetime reduction. To provide stable and reliable laser systems design, guidelines and maximum feedback ratings have to be found. We present a model to estimate the optical feedback power coupled back into the laser diode waveguide. It includes several origins of optical feedback and wide range of optical elements. The failure thresholds of InGaAs and AlGaAs bars have been determined not only at standard operation mode but at various working points. The influence of several feedback levels to laser diode lifetime is investigated up to 4000h. The analysis of the semiconductor itself leads to a better understanding of the degradation process by defect spread. Facet microscopy, LBIC- and electroluminescence measurements deliver detailed information about semiconductor defects before and after aging tests. Laser diode protection systems can monitor optical feedback. With this improved understanding, the emergency shutdown threshold can be set low enough to ensure laser diode reliability but also high enough to provide better machine usability avoiding false alarms.

  6. Analysis of phased-array diode lasers

    SciTech Connect

    Hardy, A.; Streifer, W.

    1985-07-01

    An improved, more accurate analysis of phased-array diode lasers is presented, which yields results that differ both qualitatively and quantitatively from those previously employed. A numerical example indicating decreased splitting in array mode gains is included.

  7. Tunable C- and L-band laser source based on colorless laser diode

    NASA Astrophysics Data System (ADS)

    Peng, P. C.; Jhang, J. J.; Peng, Y. W.; Bitew, M. A.; Chi, Y. C.; Wu, W. C.; Wang, H. Y.; Lin, G. R.; Li, C. Y.; Lu, H. H.

    2017-03-01

    In this letter, we propose and demonstrate a tunable laser source which covers C- and L-bands based on a colorless laser diode. The proposed laser source is tunable widely and it can tune single-wavelength, dual-wavelength, and triple-wavelength. Additionally, the optical side mode suppression ratio exceeds 30 dB. Since we combine the colorless laser diode with a tunable optical filter, the proposed tunable laser source stabilizes multi-wavelengths simultaneously. Our proposed tunable laser source is very useful for applications such as optical test instruments, optical communication systems, and optical fiber sensing systems.

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

    SciTech Connect

    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.

  9. Narrowband alexandrite laser injection seeded with frequency dithered diode laser

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary; Lee, H. S.; Prasad, Coorg

    1991-01-01

    Narrowband radiation is produced from a pulsed alexandrite laser when injection seeded with the output of a low power, tunable, continuous wave single mode diode laser. Injection seeded power oscillators are easier to frequency stabilize than etalon narrowed lasers, are more efficient and less prone to optical damage. AlGaAs diode lasers are available with wavelengths from 760 to 770 nm in the oxygen A band that can be used for differential absorption lidar remote sensing of atmospheric pressure and temperature. Diodes with room temperature output at 740 nm may be cooled sufficiently to emit in the water vapor absorption band at 720-730 nm for humidity remote sensing. The diode laser linewidth of 200 MHz is sufficient to seed 2 or 3 longitudinal modes of the multi-transverse mode alexandrite laser, giving the pulsed laser a bandwidth of 0.007 to 0.014/cm.

  10. Optimized high-power diode laser, laser arrays, and bars for pump applications

    NASA Astrophysics Data System (ADS)

    Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Wolf, J.; Hennig, P.

    2009-02-01

    Broad area diode laser and diode laser bars are the most efficient light sources. In comparison to solid state laser or gas laser systems the over all beam quality of the diode laser is poor. Thus most application of diode laser bars is high efficient pumping of solid state lasers converting the beam quality and scaling the power of laser systems within the kW range. The pump efficiency and the beam coupling efficiency of the diode laser pumped systems has to be increased to meet the increasing laser market demands for reduced costs. JENOPTIK Diode Lab GmbH (JDL) has optimized their high power brilliance bars to enable reliable high power operation especially, for the 9xx nm wavelength range and low far field divergences. Superior reliability with long operation time of 13,000 hours and high power operation of 200 W are demonstrated for high power bars high filling factor mounted on passively cooled heat sinks. Smaller far field divergence at high power levels requires longer cavity length and higher efficiencies in the beam coupling needs requires lower filling factors. The new high brilliance bars and arrays with 20% filling factor are showing high power operation up to 95 W and a slow axis beam divergence of less than 8° (95% power content).

  11. Low-cost automated system for phase-shifting and phase retrieval based on the tunability of a laser diode

    NASA Astrophysics Data System (ADS)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2016-09-01

    A low-cost and fully automated process for phase-shifting interferometry by continuously changing and turning on-off the input voltage of a laser diode under the scheme of an unbalanced Twyman-Green interferometer setup is presented. The input signal of a laser diode is controlled by a Data Acquisition (NI-DAQ) device which permits to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. By using Carré algorithm the phase map is obtained. Measurements of visibility and phase-shift to verify the PSI requirements are also shown.

  12. Microcollimated laser diode with low wavefront aberration

    SciTech Connect

    Ogata, S.; Sekii, H.; Maeda, T.; Goto, H.; Yamashita, T.; Imanaka, K. )

    1989-11-01

    The authors developed microcollimated laser diode( MCLD) utilizing a 1 mm short focal length, phi, lc 0.5 mm small diameter micro Fresnel lens (MFL) for the first time as the collimating lens. The MCLD is assembled with a 780 nm quantum-well laser diode dice and an MFL in the smallest commercial available laser package. The radiated laser beam form the MCLD has higher than 2mW power at 50 mA driving current, narrow enough as a phi 2 mm beam diameter with nearly Gaussian intensity profile, and low wavefront aberration less than {lambda}14 (rms value) measured at 1 m distance.

  13. Extended-cavity diode lasers with tracked resonances

    NASA Astrophysics Data System (ADS)

    Chiow, Sheng-Wey; Long, Quan; Vo, Christoph; Müller, Holger; Chu, Steven

    2007-11-01

    We present a painless, almost-free upgrade to present extended-cavity diode lasers (ECDLs) that improves the long-term mode-hop-free performance by stabilizing the resonance of the internal cavity to the external cavity. This stabilization is based on the observation that the frequency or amplitude noise of the ECDL is lowest at the optimum laser diode temperature or injection current. Thus, keeping the diode current at the level where the noise is lowest ensures mode-hop-free operation within one of the stable regions of the mode chart, even if these should drift due to external influences. This method can be applied directly to existing laser systems without modifying the optical setup. We demonstrate the method in two ECDLs stabilized to vapor cells at 852 and 895 nm wavelengths. We achieve long-term mode-hop-free operation and low noise at low power consumption, even with an inexpensive non-antireflection-coated diode.

  14. Extended-cavity diode lasers with tracked resonances.

    PubMed

    Chiow, Sheng-Wey; Long, Quan; Vo, Christoph; Müller, Holger; Chu, Steven

    2007-11-20

    We present a painless, almost-free upgrade to present extended-cavity diode lasers (ECDLs) that improves the long-term mode-hop-free performance by stabilizing the resonance of the internal cavity to the external cavity. This stabilization is based on the observation that the frequency or amplitude noise of the ECDL is lowest at the optimum laser diode temperature or injection current. Thus, keeping the diode current at the level where the noise is lowest ensures mode-hop-free operation within one of the stable regions of the mode chart, even if these should drift due to external influences. This method can be applied directly to existing laser systems without modifying the optical setup. We demonstrate the method in two ECDLs stabilized to vapor cells at 852 and 895 nm wavelengths. We achieve long-term mode-hop-free operation and low noise at low power consumption, even with an inexpensive non-antireflection-coated diode.

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

    SciTech Connect

    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.

  16. Semipolar III–nitride quantum well waveguide photodetector integrated with laser diode for on-chip photonic system

    NASA Astrophysics Data System (ADS)

    Shen, Chao; Lee, Changmin; Stegenburgs, Edgars; Holguin Lerma, Jorge; Khee Ng, Tien; Nakamura, Shuji; DenBaars, Steven P.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2017-04-01

    A high-performance waveguide photodetector (WPD) integrated with a laser diode (LD) sharing the single InGaN/GaN quantum well active region is demonstrated on a semipolar GaN substrate. The photocurrent of the integrated WPD is effectively tuned by the emitted optical power from the LD. The responsivity ranges from 0.018 to 0.051 A/W with increasing reverse bias from 0 to 10 V. The WPD shows a large 3 dB modulation bandwidth of 230 MHz. The integrated device, being used for power monitoring and on-chip communication, paves the way towards the eventual realization of a III–nitride on-chip photonic system.

  17. Small Integrated Optical Head Device Using a Blue-Violet Laser Diode for Blu-ray Disc System

    NASA Astrophysics Data System (ADS)

    Manoh, Kiyoshi; Yoshida, Hiroshi; Kobayashi, Takashi; Takase, Motohiro; Yamauchi, Kiyoshi; Fujiwara, Satoshi; Ohno, Tsuyoshi; Nishi, Noriaki; Ozawa, Masafumi; Ikeda, Masao; Tojyo, Tsuyoshi; Taniguchi, Tadashi

    2003-02-01

    We report the first integrated optical head device using a blue-violet laser diode (LD), which is a key device for realizing a small and thin Blu-ray Disc drive. While integrating seven optical elements and semiconductor chips into one device by adopting a molded optical element with high transmittance to the blue-violet wavelength, both small aberration and the small device size of 11 mm× 6 mm× 4.1 mm have been realized. We have also improved heat dissipation efficiency from this device to the base unit by adopting a newly developed package. At this time, we have implemented a performance evaluation of this small head device and have confirmed its good read/write performance as well as its adequate tolerances required for the Blu-ray Disc system.

  18. Disruptive laser diode source for embedded LIDAR sensors

    NASA Astrophysics Data System (ADS)

    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

  19. Picosecond pulsed diode ring laser gyroscope

    SciTech Connect

    Rosker, M.J.; Christian, W.R.; McMichael, I.C.

    1994-12-31

    An external ring cavity containing as its active medium a pair of InGaAsP diodes is modelocked to produce picosecond pulses. In such a laser, a small frequency difference proportional to the nonreciprocal phase shift (resulting from, e.g., the Sagnac effect) can be observed by beating together the counter propagating laser arms; the device therefore acts as a rotating sensor. In contrast to a conventional (cw) ring laser gyroscope, the pulsed gyroscope can avoid gain competition, thereby enabling the use of homogeneously broadened gain media like semiconductor diodes. Temporal separation of the pulses within the cavity also discriminates against frequency locking of the lasers. The picosecond pulsed diode ring laser gyroscope is reviewed. Both active and passive modelocking are discussed.

  20. Composite resonator vertical cavity laser diode

    SciTech Connect

    Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

    1998-05-01

    The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Ruggedized microchannel-cooled laser diode array with self-aligned microlens

    DOEpatents

    Freitas, Barry L.; Skidmore, Jay A.

    2003-11-11

    A microchannel-cooled, optically corrected, laser diode array is fabricated by mounting laser diode bars onto Si surfaces. This approach allows for the highest thermal impedance, in a ruggedized, low-cost assembly that includes passive microlens attachment without the need for lens frames. The microlensed laser diode array is usable in all solid-state laser systems that require efficient, directional, narrow bandwidth, high optical power density pump sources.

  3. 785-nm dual wavelength DBR diode lasers and MOPA systems with output powers up to 750 mW

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Maiwald, Martin; Klehr, Andreas; Müller, André; Bugge, Frank; Fricke, Jörg; Ressel, Peter; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Shifted excitation Raman difference spectroscopy (SERDS), i.e. exciting the sample alternatingly with two slightly shifted wavelengths, allows to distinguish between the Raman lines and sources of interference. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers and their application in master oscillator power amplifier (MOPA) systems at 785 nm suitable for Raman spectroscopy and SERDS will be presented. The definition of the wavelengths is made by implementing deeply-etched 10th order 500 μm long surface gratings with different periods using i-line wafer stepper lithography. Y-branch DBR lasers with a total length of 3 mm and a stripe width of 2.2 μm were manufactured and characterized. The monolithic devices reach output powers up to 215 mW with emission widths of about 20 pm. At 200 mW the conversion efficiency is 20%, i.e. the electrical power consumption is only 1 W. The spectral distance between the two laser cavities is about 0.6 nm, i.e. 10 cm-1 as targeted. The side mode suppression ratio is better than 50 dB. Amplifying these devices using a ridge waveguide amplifier an output power of about 750 mW could be achieved maintaining the spectral properties of the master oscillator.

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

    SciTech Connect

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

    2015-07-15

    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.

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

    PubMed

    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.

  6. Thermal management, beam control, and packaging designs for high power diode laser arrays and pump cavity designs for diode laser array pumped rod shaped lasers

    NASA Astrophysics Data System (ADS)

    Chung, Te-Yuan

    Several novel techniques for controlling, managing and utilizing high power diode lasers are described. Low pressure water spray cooling for a high heat flux system is developed and proven to be an ideal cooling method for high power diode laser arrays. In order to enable better thermal and optical performance of diode laser arrays, a new and simple optical element, the beam control prism, is invented. It provides the ability to accomplish beam shaping and beam tilting at the same time. Several low thermal resistance diode packaging designs using beam control prisms are proposed, studied and produced. Two pump cavity designs using a diode laser array to uniformly pump rod shape gain media are also investigated.

  7. Design of drive circuit of laser diode

    NASA Astrophysics Data System (ADS)

    Ran, Yingying; Huang, Xuegong; Xu, Xiaobin

    2016-10-01

    Aiming at the difficult problem of high precision frequency stabilization of semiconductor laser diode, the laser frequency control is realized through the design of the semiconductor drive system. Above all, the relationship between the emission frequency and the temperature of LD is derived theoretically. Then the temperature corresponding to the stable frequency is obtained. According to the desired temperature stability of LD, temperature control system is designed, which is composed of a temperature setting circuit, temperature gathering circuit, the temperature display circuit, analog PID control circuit and a semiconductor refrigerator control circuit module. By sampling technology, voltage of platinum resistance is acquired, and the converted temperature is display on liquid crystal display. PID analog control circuit controls speed stability and precision of temperature control. The constant current source circuit is designed to provide the reference voltage by a voltage stabilizing chip, which is buffered by an operational amplifier. It is connected with the MOSFET to drive the semiconductor laser to provide stable current for the semiconductor laser. PCB circuit board was finished and the experimental was justified. The experimental results show that: the design of the temperature control system could achieve the goal of temperature monitoring. Meanwhile, temperature can be stabilized at 40°C +/- 0.1°C. The output voltage of the constant current source is 2 V. The current is 35 mA.

  8. Laser transurethral resection of the prostate: Safety study of a novel system of photoselective vaporization with high power diode laser in prostates larger than 80mL.

    PubMed

    Andrés, G; Arance, I; Gimbernat, H; Redondo, C; García-Tello, A; Angulo, J C

    2015-01-01

    To present the feasibility of photoselective vaporization of the prostate (PVP) with of a new diode laser-resection system. Surgical treatment of benign prostatic hyperplasia (BPH) is constantly evolving. Laser techniques are increasingly used in prostates of large size. A prospective study was performed to evaluate operative data and patient outcomes with PVP using high-power diode laser (HPD) and a novel quartz-head fiber with shovel shape in patients with prostate>80mL. Demographic data, operative time, hemoglobin loss, operative results (IPSS, quality of life (QoL), Qmax, post void residue (PVR), IIEF-5 and micturition diary) and complications following Clavien-Dindo classification are described. Thirty-one patients were included in the study. Sixteen (51.6%) were on active antiplatelet treatment and 12 (38.7%) had received anticoagulants before surgery. All cases were followed at least 6mo. No intraoperative or postoperative major complications occurred. Three patients (9.7%) had minor complications according to Clavien-Dindo classification. Twenty-seven (87.1%) were discharged on postoperative day one without catheter. There were significant improvements in IPSS, QoL, Qmax and PVR, both at 3 and 6mo (P<.0001), but sexual function according to IIEF-5 showed no differences. Urgency (any grade) increased at 3mo (48.4%; P=.002) and considerably decreased at 6mo (9.7%; P<.0001). This pilot experience with shovel shape fiber and HPD is encouraging. It shows that laser-resection is a safe procedure, achieving excellent results in terms of IPSS, QoL and Qmax in large prostates even in high-risk patients. Longer follow-up, comparative and randomized controlled studies are needed to widespread these results. Copyright © 2014 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. High average power, diode pumped petawatt laser systems: a new generation of lasers enabling precision science and commercial applications

    NASA Astrophysics Data System (ADS)

    Haefner, C. L.; Bayramian, A.; Betts, S.; Bopp, R.; Buck, S.; Cupal, J.; Drouin, M.; Erlandson, A.; Horáček, J.; Horner, J.; Jarboe, J.; Kasl, K.; Kim, D.; Koh, E.; Koubíková, L.; Maranville, W.; Marshall, C.; Mason, D.; Menapace, J.; Miller, P.; Mazurek, P.; Naylon, A.; Novák, J.; Peceli, D.; Rosso, P.; Schaffers, K.; Sistrunk, E.; Smith, D.; Spinka, T.; Stanley, J.; Steele, R.; Stolz, C.; Suratwala, T.; Telford, S.; Thoma, J.; VanBlarcom, D.; Weiss, J.; Wegner, P.

    2017-05-01

    Large laser systems that deliver optical pulses with peak powers exceeding one Petawatt (PW) have been constructed at dozens of research facilities worldwide and have fostered research in High-Energy-Density (HED) Science, High-Field and nonlinear physics [1]. Furthermore, the high intensities exceeding 1018W/cm2 allow for efficiently driving secondary sources that inherit some of the properties of the laser pulse, e.g. pulse duration, spatial and/or divergence characteristics. In the intervening decades since that first PW laser, single-shot proof-of-principle experiments have been successful in demonstrating new high-intensity laser-matter interactions and subsequent secondary particle and photon sources. These secondary sources include generation and acceleration of charged-particle (electron, proton, ion) and neutron beams, and x-ray and gamma-ray sources, generation of radioisotopes for positron emission tomography (PET), targeted cancer therapy, medical imaging, and the transmutation of radioactive waste [2, 3]. Each of these promising applications requires lasers with peak power of hundreds of terawatt (TW) to petawatt (PW) and with average power of tens to hundreds of kW to achieve the required secondary source flux.

  10. A Modular Control Platform for a Diode Pumped Alkali Laser

    NASA Astrophysics Data System (ADS)

    Shapiro, J.; Teare, S.

    Many of the difficulties of creating compact, high power laser systems can be overcome if the heat dissipating properties of chemical lasers can be combined with the efficiency of diode lasers. Recently, the novel idea of using solid state diode lasers to pump gaseous gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and early experiments have shown promising results. However, a number of technical issues need to be overcome to realize high output power from these lasers. In order to achieve higher power, the efficiency of coupling between pump laser energy and the chemical cell must be increased, and eventually multiple high power diode pumps must be combined and synchronized so that their energy can pump the chemical cell. Additionally, an inter-cavity adaptive optics system may be a requirement to be able to propagate these lasers with high efficiency. DPAL systems are complex and require a significant amount of data fusion and active feedback to control and optimize their performance. There are a wide range of components including pump lasers, gain cells and monitoring points needed to study and refine the overall laser system. In support of this dynamic development environment, we have developed a hardware framework using commercial off the shelf (COTS) components which supports the rapid assembly of functional system blocks into a cohesive integrated system. Critical to this system are a simple communication protocol, industry standard communication pipes (USB, Bluetooth, etc), and flexible high level scripting. Simplifying the integration process has the benefit of allowing flexible "on the fly" modifications to adapt the system as needed and enhance available functionality. The modular nature of the architecture allows scalability and adaptability as more pieces are added to the system. Key components of this system are demonstrated for selected portions of a DPAL system using a USB backbone.

  11. Absolute distance interferometry using diode lasers

    NASA Astrophysics Data System (ADS)

    Meiners-Hagen, K.; Abou-Zeid, A.; Hartmann, L.

    2008-10-01

    An approach to a homodyne absolute distance interferometer (ADI) was previously presented which makes use of two extended cavity diode lasers (ECDL). The length measurement is performed by combining variable synthetic wavelength interferometry and two wavelength interferometry in one setup. In this contribution the ADI was compared to a counting HeNe laser interferometer up to a length of 10 m.

  12. 250W diode laser for low pressure Rb vapor pumping

    NASA Astrophysics Data System (ADS)

    Podvyaznyy, A.; Venus, G.; Smirnov, V.; Mokhun, O.; Koulechov, V.; Hostutler, D.; Glebov, L.

    2010-02-01

    The diode pumped alkali vapor lasers operating at subatmospheric pressure require developing of a new generation of high-power laser diode sources with about 10 GHz wide emission spectrum. The latest achievements in the technology of volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass opened new opportunities for the design and fabrication of compact external cavity laser diodes, diode bars and stacks with reflecting VBGs as output couplers. We present a diode laser system providing up to 250 W output power and emission spectral width of 20 pm (FWHM) at the wavelength of 780 nm. The stability and position of an emission wavelength is determined by the resonant wavelength of a VBG which is controlled by temperature. Stability of an emitting wavelength is within 5 pm. Thermal tuning of the wavelength provides maximum overlapping of emitting line with absorption spectrum of a Rb (rubidium)- cell. The designed system consists of 7 modules tuned to the same wavelength corresponding to D2 spectral line of Rb87 or Rb85 and coupled to a single output fiber. Analogous systems could be used for other Rb isotopes spectral lines as well as for lasers based on other alkali metal vapors (Cs and K) or any agents with narrow absorption lines.

  13. Diode-side-pumped Alexandrite slab lasers.

    PubMed

    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 TEM00 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.

  14. Power blue and green laser diodes and their applications

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. Laser-assisted skin closure (LASC) using a 815-nm diode laser system: determination of an optimal dose to accelerate wound healing

    NASA Astrophysics Data System (ADS)

    Capon, Alexandre; Mitchell, Valerie A.; Sumian, Chryslain C.; Gauthier, Beatrice; Mordon, Serge R.

    1999-01-01

    This study aimed to evaluate a 815 nm diode-laser system to assist wound closure. It was proposed to determine an optimal fluence being able to accelerate and improve heating process without thermal damage after laser irradiation. Male hairless rats with dorsal skin incisions were used for the study. Different fluences were screened (76 to 346 J/cm2) in a first phase with clinical examination at 3, 7, 15 and 21 days after surgery. Best results were obtained for a fluence of 145 J/cm2 and 3 sec time of exposure. A second phase was conducted to valid these parameters with histological study and determination of tensile strength at 3, 7, 15 and 21 days after surgery. LASC was 4 times faster to process than conventional suture. In the laser group with an optimal fluence of 145 J/cm2, healing was accelerated. The resulting scar was more indiscernible than in the control groups. Histological aspect was better with continuous epidermis and dermis at 3 days in most cases. Tensile strength was 30 to 58% greater than in control groups (1141 g/cm2 at 7 days in the laser group versus 856 g/cm2 and 724 g/cm2 in the control groups, p < 0.001).

  17. Diode laser-pumped solid-state lasers

    NASA Technical Reports Server (NTRS)

    Fan, Tso Yee; Byer, Robert L.

    1988-01-01

    Recently, interest in diode laser-pumped solid-state lasers has increased due to their advantages over flashlamp-pumped solid-state lasers. A historical overview is presented of semiconductor diode-pumped solid-state lasers beginning with work in the early 1960s and continuing through recent work on wavelength extension of these devices by laser operation on new transitions. Modeling of these devices by rate equations to obtain expressions for threshold, slope efficiency, and figures of merit is also given.

  18. Diode-laser-based therapy device

    NASA Astrophysics Data System (ADS)

    Udrea, Mircea V.; Nica, Adriana S.; Florian, Mariana; Poenaru, Daniela; Udrea, Gabriela; Lungeanu, Mihaela; Sporea, Dan G.; Vasiliu, Virgil V.; Vieru, Roxana

    2004-10-01

    A new therapy laser device is presented. The device consists of a central unit and different types of laser probes. The laser probe model SL7-650 delivers seven red (650 nm), 5 mW diode lasers convergent beams. The beams converge at about 30 cm in front of the laser probe and the irradiated area might be varied by simple displacement of the laser probe with respect to the target. The laser probe SL1-808 emits single infrared laser beam up to 500 mW. The efficiency of the use of this device in physiotherapy, and rheumatology, has been put into evidence after years of testing. Dermatology and microsurgery are users of infrared powerful laser probes. The device has successfully passed technical and clinical tests in order to be certified. The laser device design and some medical results are given.

  19. Robust modeling and performance analysis of high-power diode side-pumped solid-state laser systems.

    PubMed

    Kashef, Tamer; Ghoniemy, Samy; Mokhtar, Ayman

    2015-12-20

    In this paper, we present an enhanced high-power extrinsic diode side-pumped solid-state laser (DPSSL) model to accurately predict the dynamic operations and pump distribution under different practical conditions. We introduce a new implementation technique for the proposed model that provides a compelling incentive for the performance assessment and enhancement of high-power diode side-pumped Nd:YAG lasers using cooperative agents and by relying on the MATLAB, GLAD, and Zemax ray tracing software packages. A large-signal laser model that includes thermal effects and a modified laser gain formulation and incorporates the geometrical pump distribution for three radially arranged arrays of laser diodes is presented. The design of a customized prototype diode side-pumped high-power laser head fabricated for the purpose of testing is discussed. A detailed comparative experimental and simulation study of the dynamic operation and the beam characteristics that are used to verify the accuracy of the proposed model for analyzing the performance of high-power DPSSLs under different conditions are discussed. The simulated and measured results of power, pump distribution, beam shape, and slope efficiency are shown under different conditions and for a specific case, where the targeted output power is 140 W, while the input pumping power is 400 W. The 95% output coupler reflectivity showed good agreement with the slope efficiency, which is approximately 35%; this assures the robustness of the proposed model to accurately predict the design parameters of practical, high-power DPSSLs.

  20. Rugged, Tunable Extended-Cavity Diode Laser

    NASA Technical Reports Server (NTRS)

    Moore, Donald; Brinza, David; Seidel, David; Klipstein, William; Choi, Dong Ho; Le, Lam; Zhang, Guangzhi; Iniguez, Roberto; Tang, Wade

    2007-01-01

    A rugged, tunable extended-cavity diode laser (ECDL) has been developed to satisfy stringent requirements for frequency stability, notably including low sensitivity to vibration. This laser is designed specifically for use in an atomic-clock experiment to be performed aboard the International Space Station (ISS). Lasers of similar design would be suitable for use in terrestrial laboratories engaged in atomic-clock and atomic-physics research.

  1. Phase Noise Reduction of Laser Diode

    NASA Technical Reports Server (NTRS)

    Zhang, T. C.; Poizat, J.-Ph.; Grelu, P.; Roch, J.-F.; Grangier, P.; Marin, F.; Bramati, A.; Jost, V.; Levenson, M. D.; Giacobino, E.

    1996-01-01

    Phase noise of single mode laser diodes, either free-running or using line narrowing technique at room temperature, namely injection-locking, has been investigated. It is shown that free-running diodes exhibit very large excess phase noise, typically more than 80 dB above shot-noise at 10 MHz, which can be significantly reduced by the above-mentioned technique.

  2. Diode laser power module for beamed power transmission

    NASA Technical Reports Server (NTRS)

    Choi, S. H.; Williams, M. D.; Lee, J. H.; Conway, E. J.

    1991-01-01

    Recent progress with powerful, efficient, and coherent monolithic diode master-oscillator/power-amplifier (M-MOPA) systems is promising for the development of a space-based diode laser power station. A conceptual design of a 50-kW diode laser power module was made for space-based power stations capable of beaming coherent power to the moon, Martian rovers, or other satellites. The laser diode power module consists of a solar photovoltaic array or nuclear power source, diode laser arrays (LDAs), a phase controller, beam-steering optics, a thermal management unit, and a radiator. Thermal load management and other relevant aspects of the system (such as power requirements and system mass) are considered. The 50-kW power module described includes the highest available efficiency of LD M-MOPA system to date. However, the overall efficiency of three amplifier stages, including the coupling efficiency, turns out to be 55.5 percent. Though a chain of PA stages generates a high-power coherent beam, there is a penalty due to the coupling loss between stages. The specific power of the 50-kW module using solar power is 6.58 W/kg.

  3. Diode laser power module for beamed power transmission

    NASA Technical Reports Server (NTRS)

    Choi, S. H.; Williams, M. D.; Lee, J. H.; Conway, E. J.

    1991-01-01

    Recent progress with powerful, efficient, and coherent monolithic diode master-oscillator/power-amplifier (M-MOPA) systems is promising for the development of a space-based diode laser power station. A conceptual design of a 50-kW diode laser power module was made for space-based power stations capable of beaming coherent power to the moon, Martian rovers, or other satellites. The laser diode power module consists of a solar photovoltaic array or nuclear power source, diode laser arrays (LDAs), a phase controller, beam-steering optics, a thermal management unit, and a radiator. Thermal load management and other relevant aspects of the system (such as power requirements and system mass) are considered. The 50-kW power module described includes the highest available efficiency of LD M-MOPA system to date. However, the overall efficiency of three amplifier stages, including the coupling efficiency, turns out to be 55.5 percent. Though a chain of PA stages generates a high-power coherent beam, there is a penalty due to the coupling loss between stages. The specific power of the 50-kW module using solar power is 6.58 W/kg.

  4. Stirling-Cycle Cooling For Tunable Diode Laser

    NASA Technical Reports Server (NTRS)

    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.

  5. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

    2016-01-01

    To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm-1 (1343.3 nm) and 7185.6 cm-1 (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

  6. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction.

    PubMed

    Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

    2016-01-01

    To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm(-1) (1343.3 nm) and 7185.6 cm(-1) (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

  7. Blue-emitting external cavity laser diode

    NASA Astrophysics Data System (ADS)

    Na, Hong Man; Song, Hong Joo; Park, Jong Hwan; Lee, Jun Ho; Park, Jung Ho

    2016-03-01

    An front facet anti-reflection coated solitary laser diode is operated in the external cavity diode laser (ECDL). For wavelength stabilization and narrow spectral width, the diffraction grating is used in a Littrow configuration. At an injection current of 280 mA, a output power of 35mW with a slope efficiency of 0.22 W/A and the bandwidth of 80 pm at a wavelength of 457 nm. In this paper, the tunable external cavity diode laser module is designed with an overall size of 18 mm x 24 mm x 14 mm. ECDL showed excellent wavelength locking behavior without a non-shift of the peak wavelength.

  8. The MVACS tunable diode laser spectrometers

    NASA Astrophysics Data System (ADS)

    May, Randy D.; Forouhar, Siamak; Crisp, David; Woodward, W. Stephen; Paige, David A.; Pathare, Asmin; Boynton, William V.

    2001-08-01

    Two independent tunable diode laser spectrometers are resident aboard the Mars Polar Lander as part of the Mars Volatiles and Climate Surveyor payload. One spectrometer is located on the meteorological mast for measurements of H2O and CO2 in the free atmosphere, and the other serves as the H2O and CO2 analyzer for the Thermal and Evolved Gas Analyzer. Water vapor is measured using a tunable diode laser operating at 1.37 μm, while CO2 is measured using a second laser operating near 2.05 μm. The 2.05 μm laser also has isotopic analysis capability. In addition to the major CO2 isotopomer (12C16O16O), analyses of 13C16O16O and 12C18O16O in the atmosphere and in the Thermal and Evolved Gas Analyzer are possible under certain conditions. The spectrometers were designed and built at the Jet Propulsion Laboratory and have their heritage in a series of tunable diode laser spectrometers developed for Earth atmospheric studies using high-altitude aircraft and balloon platforms. The 1.37 μm diode laser on the meteorological mast will provide the first in situ measurements of water vapor in the Martian boundary layer, with a detection sensitivity an order of magnitude greater than the water vapor abundances inferred from the remote-sensing observations by the Viking Orbiters.

  9. Diode pumped Nd:YAG laser development

    NASA Technical Reports Server (NTRS)

    Reno, C. W.; Herzog, D. G.

    1976-01-01

    A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.

  10. Novel high-brightness fiber coupled diode laser device

    NASA Astrophysics Data System (ADS)

    Haag, Matthias; Köhler, Bernd; Biesenbach, Jens; Brand, Thomas

    2007-02-01

    High brightness becomes more and more important in diode laser applications for fiber laser pumping and materials processing. For OEM customers fiber coupled devices have great advantages over direct beam modules: the fiber exit is a standardized interface, beam guiding is easy with nearly unlimited flexibility. In addition to the transport function the fiber serves as homogenizer: the beam profile of the laser radiation emitted from a fiber is symmetrical with highly repeatable beam quality and pointing stability. However, efficient fiber coupling requires an adaption of the slow-axis beam quality to the fiber requirements. Diode laser systems based on standard 10mm bars usually employ beam transformation systems to rearrange the highly asymmetrical beam of the laser bar or laser stack. These beam transformation systems (prism arrays, lens arrays, fiber bundles etc.) are expensive and become inefficient with increasing complexity. This is especially true for high power devices with small fiber diameters. On the other hand, systems based on single emitters are claimed to have good potential in cost reduction. Brightness of the inevitable fiber bundles, though, is limited due to inherent fill-factor losses. At DILAS a novel diode laser device has been developed combining the advantages of diode bars and single emitters: high brightness at high reliability with single emitter cost structure. Heart of the device is a specially tailored laser bar (T-Bar), which epitaxial and lateral structure was designed such that only standard fast- and slow-axis collimator lenses are required to couple the beam into a 200μm fiber. Up to 30 of these T-Bars of one wavelength can be combined to reach a total of > 500W ex fiber in the first step. Going to a power level of today's single emitter diodes even 1kW ex 200μm fiber can be expected.

  11. Research and Development of Laser Diode Based Instruments for Applications in Space

    NASA Technical Reports Server (NTRS)

    Krainak, Michael; Abshire, James; Cornwell, Donald; Dragic, Peter; Duerksen, Gary; Switzer, Gregg

    1999-01-01

    Laser diode technology continues to advance at a very rapid rate due to commercial applications such as telecommunications and data storage. The advantages of laser diodes include, wide diversity of wavelengths, high efficiency, small size and weight and high reliability. Semiconductor and fiber optical-amplifiers permit efficient, high power master oscillator power amplifier (MOPA) transmitter systems. Laser diode systems which incorporate monolithic or discrete (fiber optic) gratings permit single frequency operation. We describe experimental and theoretical results of laser diode based instruments currently under development at NASA Goddard Space Flight Center including miniature lidars for measuring clouds and aerosols, water vapor and wind for Earth and planetary (Mars Lander) use.

  12. Novel high peak current pulsed diode laser sources for direct material processing

    NASA Astrophysics Data System (ADS)

    Traub, M.; Bock, M.; Hoffmann, H.-D.; Bartram, M.

    2007-02-01

    Diode laser systems are well established for applications which demand high continuous wave (cw) power. These applications are material processing like cutting and welding of metals as well as polymers where diode laser systems are less expensive and more compact than solid state lasers. Even though the optical output power and the beam quality of diode lasers are increasing steadily, the use of these sources is generally limited to cw applications. For processes during which ablating of material is demanded, however, conventional diode lasers are inferior compared to pulsed solid state lasers as diode lasers suffer from the absence of optical intracavity q-switching. Some examples of these applications are coating removal and marking. To overcome this drawback, we have developed several diode laser systems that use high peak-current drivers and thereby allow to operate the diode lasers at currents up to 500 A. The pulse source was tested with fiber coupled single emitters, conventional diode lasers and customized AR-coated diode laser bars. With the new diode laser driver, a peak output power of 250 W can be achieved with pulse durations of approx. 100 ns. Polarization coupling of two bars increases the power by a factor of two. Thereby an output power of 500 W can be demonstrated. These systems reach an intensity of 27 MW/cm2 per diode laser bar which is sufficient for ablating processes. We will demonstrate the design of the prototype system as well as results of marking and coating removal experiments with the system.

  13. Design Considerations for the Diode-pumped Laser Ignition Project

    DTIC Science & Technology

    2013-01-01

    Design Considerations for the Diode - pumped Laser Ignition Project by Jeffrey O. White ARL-TN-0526 January 2013...Design Considerations for the Diode - pumped Laser Ignition Project Jeffrey O. White Sensors and Electron Devices Directorate, ARL...August 2012 4. TITLE AND SUBTITLE Design Considerations for the Diode - pumped Laser Ignition Project 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  14. Photodynamic therapy laser system

    NASA Astrophysics Data System (ADS)

    Shu, Xiaoqin; Lin, Qing; Wang, Feng; Shu, Chao; Wang, Jianhua

    2009-08-01

    Photodynamic therapy (PDT) treatment is a new treatment for tumour and Dermatology. With the successful development of the second-generation photosensitizer and the significant manifestations in clinics, PDT has shown a more extensive application potentials. To activate the photosensitizer, in this paper, we present a GaAs-based diode laser system with a wavelength of 635 nm. In this system, to prolong the working life-time of the diode lasers, we use specific feedback algorithm to control the current and the temperature of the diode laser with high precision. The clinic results show an excellent effect in the treatment of Condyloma combined with 5-ALA.

  15. INITIAL EXPERIENCE WITH TRANSPUPILLARY DIODE LASER PHOTOCOAGULATION FOR RETINAL DISEASES.

    PubMed

    Uhumwangho, O M; Iyiriaro, Iao

    2014-01-01

    Lasers are an invaluable treatment modality for the management of some retinovascular diseases. One of these lasers is the diode laser which is easy to procure and maintain. To review the outcomes of diode laser photocoagulation in patients with a variety of retinal conditions. A retrospective case series of all patients who had retinal laser photocoagulation between July 2012 and June 2014 with the semiconductor infrared diode laser was performed. Demographic and clinical data collected included age, sex, eye involved, visual acuity, diagnosis, associated systemic and ocular diseases, intra and post treatment findings, laser treatment parameters and follow up. A total of 22 eyes of 15 patients had diode laser treatment during the period under review comprising 8(53.3%) males and 7(46.7%) females with a mean age at presentation of 53.4±8.9 years. The indications for treatment were proliferative diabetic retinopathy in 18(81.8%) eyes of 11 patients, retinal vein occlusion in 2(9.1%) eyes of 2 patients and retinal breaks with lattice in 2(9.1%) eyes of 2 patients with fellow eye retinal detachment. Visual acuity in eyes with diabetic retinopathy improved in 9(50%) eyes, worsened in 3(16.7%) eyes and was unchanged/ stable in 6(33.3%) eyes. Regression of neovascularization was achieved in 2(100%) eyes with retinal vein occlusion. The retina of the 2(100%) eyes with breaks following retinopexy remained attached during the follow up period. The follow up period ranged from 2 days to 2 years with a mean duration of 13.5±15.8 months. The diode laser is an effective and beneficial treatment modality in the management of proliferative retinopathies and some retinal diseases.

  16. 975nm high-peak power ns-diode laser based MOPA system suitable for water vapor DIAL applications

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Klehr, Andreas; Vu, Thi Nghiem; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Micro-DIAL (differential absorption LIDAR) systems require light sources with peak powers in the range of several 10 W together with a spectral line width smaller than the width of absorption lines under study. For water vapor at atmospheric pressure this width should be smaller than 10 pm at 975 nm. In this paper, an all semiconductor master oscillator power amplifier system at an emission wavelength of 975 nm will be presented. This spectral range was selected with respect to a targeted absorption path length of 5000 m and H2O line strengths. A distributed feedback (DFB) ridge waveguide diode laser operated in continuous wave is used as master oscillator whereas a tapered amplifier consisting of a RW section and a flared section is implemented as power amplifier. The RW section acts as optical gate. The current pulses injected into the RW part have a length of 8 ns and the tapered part is driven with 15 ns long pulses. The delay between the pulses is adjusted for optimal pulse shape. The repetition rate is in both cases 25 kHz. A maximal pulse output power of about 16 W limited by the available current supply is achieved. The spectral line width of the system determined by the properties of the DFB laser is smaller than 10 pm. The tuning range amounts 0.9 nm and a SMSR of 40 dB is observed. From the dependence of the peak power on the power injected into the tapered amplifier, the saturation power is determined to 5.3 mW.

  17. High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

    DOEpatents

    Freitas, Barry L.

    1998-01-01

    An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver>4kW/cm2 of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources.

  18. High density, optically corrected, micro-channel cooled, v-groove monolithic laser diode array

    DOEpatents

    Freitas, B.L.

    1998-10-27

    An optically corrected, micro-channel cooled, high density laser diode array achieves stacking pitches to 33 bars/cm by mounting laser diodes into V-shaped grooves. This design will deliver > 4kW/cm{sup 2} of directional pulsed laser power. This optically corrected, micro-channel cooled, high density laser is usable in all solid state laser systems which require efficient, directional, narrow bandwidth, high optical power density pump sources. 13 figs.

  19. Characterization of Gallium Indium Phosphide and Progress of Aluminum Gallium Indium Phosphide System Quantum-Well Laser Diode

    PubMed Central

    Hamada, Hiroki

    2017-01-01

    Highly ordered gallium indium phosphide layers with the low bandgap have been successfully grown on the (100) GaAs substrates, the misorientation toward [01−1] direction, using the low-pressure metal organic chemical vapor deposition method. It is found that the optical properties of the layers are same as those of the disordered ones, essentially different from the ordered ones having two orientations towards [1−11] and [11−1] directions grown on (100) gallium arsenide substrates, which were previously reported. The bandgap at 300 K is 1.791 eV. The value is the smallest ever reported, to our knowledge. The high performance transverse stabilized AlGaInP laser diodes with strain compensated quantum well structure, which is developed in 1992, have been successfully obtained by controlling the misorientation angle and directions of GaAs substrates. The structure is applied to quantum dots laser diodes. This paper also describes the development history of the quantum well and the quantum dots laser diodes, and their future prospects. PMID:28773227

  20. Adjustable mounting device for high-volume production of beam-shaping systems for high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Haag, Sebastian; Bernhardt, Henning; Rübenach, Olaf; Haverkamp, Tobias; Müller, Tobias; Zontar, Daniel; Brecher, Christian

    2015-02-01

    In many applications for high-power diode lasers, the production of beam-shaping and homogenizing optical systems experience rising volumes and dynamical market demands. The automation of assembly processes on flexible and reconfigurable machines can contribute to a more responsive and scalable production. The paper presents a flexible mounting device designed for the challenging assembly of side-tab based optical systems. It provides design elements for precisely referencing and fixating two optical elements in a well-defined geometric relation. Side tabs are presented to the machine allowing the application of glue and a rotating mechanism allows the attachment to the optical elements. The device can be adjusted to fit different form factors and it can be used in high-volume assembly machines. The paper shows the utilization of the device for a collimation module consisting of a fast-axis and a slow-axis collimation lens. Results regarding the repeatability and process capability of bonding side tab assemblies as well as estimates from 3D simulation for overall performance indicators achieved such as cycle time and throughput will be discussed.

  1. High-power cw operation of diode laser transversely-pumped Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Golla, Dirk; Knoke, S.; Schoene, Wolfram; Ernst, G.; Tuennermann, Andreas; Welling, Herbert

    1995-04-01

    We report on diode laser side-pumped, cw Nd:YAG rod lasers operating at pump powers up to 1 kW. With linear diode laser arrays as pump sources a pump power of 90 W/cm is realized. In multimode operation at 1064 nm, output powers of more than 300 W cw are observed. Applying a dynamically stable resonator design, an output power of more than 45 W in TEM00 mode operation is realized with an optical-to-optical efficiency of more than 11%. Higher pump powers up to several 100 W/cm can be achieved by using fiber-coupled diode lasers as pump sources. Laser performance, thermal properties and possible applications of these laser systems will be discussed.

  2. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  3. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  4. A Treatment of Amblyopia Using Laser Diodes

    NASA Astrophysics Data System (ADS)

    Wang, Di; Wang, Yi-Ding; Liu, Bing-Chun

    2000-04-01

    We propose the treatment of amblyopia using yellow-green laser diodes. There are amblyopia children in excess of fifty million in the world. Because the causative agent of amblyopia hasn't been well understood,only roughly considered to be concerned with visual sense cell, optic nerve network and function of nerve center, no appropriate treatment is found up to date. The vision of person is determined by the center hollow region of retina, where there are three kinds of cone cell. The corresponding peak wavelength in absorption spectrum locates 447nm (blue light), 532nm (green light) and 565nm (yellow light), respectively. When stimulated by white light, excited degree of three kinds of cone cell are identical,or yellow-green light, to which person eye is most sensitive, will significantly takes effects. Therefore the yellow-green laser diode is suitable for treating amblyopia. The weak laser, namely laser power less than mW order of magnitude, shows curative by stimulating bion tissue. When stimulating light power density is less than 0.001W/cm, the compounding speed of nucleic acid DNA is significantly increased. The growth rate of cell, activity of enzyme, content of hemoglobin and the growth of blood vessel, are all increased. However, it's key to control the dose of light. When the dose transcend some value, a inhibition will occur. The little dose of weak laser treatment can be accumulated with a parabolic characteristics, that is the weak laser generate bion response stengthening gradually versus time. Then it will weaken gradually after the peak. When the treatment duration is longer than a certain time, a inhibition also takes place. A suggested theraphy is characterized by little dose and short treatment course. In a conclusion, the yellow-green laser diode should be used for the treatment of amblyopia. The little dose and short treatment couse are to be adopted. Key words:treatment amblyopia laser diode

  5. DFB diode seeded low repetition rate fiber laser system operating in burst mode

    NASA Astrophysics Data System (ADS)

    Šajn, M.; Petelin, J.; Agrež, V.; Vidmar, M.; Petkovšek, R.

    2017-02-01

    A distributed feedback (DFB) diode, gain switched to produce pulses from 60 ps at high peak power of over 0.5 W, is used in burst mode to seed a fiber amplifier chain. High seed power, spectral filtering between amplifier stages and pulsed pumping are used to mitigate amplified spontaneous emission (ASE). The effect of pulse pumping synchronized with the seed on the ASE is explored for the power amplifier at low repetition. Different input and output energies at different burst repetition rates are examined and up to 85% reduction in ASE is achieved compared to continuous pumping. Finally, a numerical model is used to predict further reduction of ASE.

  6. Advances in laser diodes for pyrotechnic applications

    NASA Technical Reports Server (NTRS)

    Craig, Richard R.

    1993-01-01

    Background information concerning the use of laser diodes in pyrotechnic applications is provided in viewgraph form. The following topics are discussed: damage limits, temperature stability, fiber coupling issues, and small (100 micron) and large (400 micron) fiber results. The discussions concerning fiber results concentrate on the areas of package geometry and electro-optical properties.

  7. Monolithic resonant optical reflector laser diodes

    NASA Astrophysics Data System (ADS)

    Hirata, T.; Suehiro, M.; Maeda, M.; Hihara, M.; Hosomatsu, H.

    1991-10-01

    The first monolithic resonant optical reflector laser diode that has a waveguide directional coupler and two DBR reflectors integrated by compositional disordering of quantum-well heterostructures is described. A linewidth of 440 kHz was obtained, and this value is expected to be greatly decreased by reducing the propagation loss in the integrated waveguide.

  8. Diode Laser Sensor for Scramjet Inlets

    DTIC Science & Technology

    2011-06-03

    separately mounted in a hollow box to a solid aluminum block with spaces milled out for the optical components. This reduces the number of additional...Society to perform tests at subsonic and transonic speeds in the DSTO transonic facility using O2 diode laser absorption spectroscopy. • The presentation

  9. Diode Laser Excision of Oral Benign Lesions

    PubMed Central

    Mathur, Ena; Sareen, Mohit; Dhaka, Payal; Baghla, Pallavi

    2015-01-01

    Introduction: Lasers have made tremendous progress in the field of dentistry and have turned out to be crucial in oral surgery as collateral approach for soft tissue surgery. This rapid progress can be attributed to the fact that lasers allow efficient execution of soft tissue procedures with excellent hemostasis and field visibility. When matched to scalpel, electrocautery or high frequency devices, lasers offer maximum postoperative patient comfort. Methods: Four patients agreed to undergo surgical removal of benign lesions of the oral cavity. 810 nm diode lasers were used in continuous wave mode for excisional biopsy. The specimens were sent for histopathological examination and patients were assessed on intraoperative and postoperative complications. Results: Diode laser surgery was rapid, bloodless and well accepted by patients and led to complete resolution of the lesions. The excised specimen proved adequate for histopathological examination. Hemostasis was achieved immediately after the procedure with minimal postoperative problems, discomfort and scarring. Conclusion: We conclude that diode lasers are rapidly becoming the standard of care in contemporary dental practice and can be employed in procedures requiring excisional biopsy of oral soft tissue lesions with minimal problems in histopathological diagnosis. PMID:26464781

  10. Real-time power measurement and control for high power diode laser

    NASA Astrophysics Data System (ADS)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Wang, Zhi-yong

    2011-06-01

    As the continual improvement of technology and beam quality, diode laser, with poor beam quality, no longer just apply to pump solid-state laser. As a kind of implement of laser materials processing, high-power diode laser has been used in manufacture, as a brand new means of laser processing. Due to the influence of inevitable unstable factors, for example, the temperature of water-cooler, the current of power supply, etc, the output power of diode laser will be unstable. And laser output power, as an important parameter, frequently affects the performance of the laser beam and the experimental results of processing, especially in the laser materials processing. Therefore, researching the real-time power measurement and control of high power diode laser has great significance, and for diode laser, it would improve performance of itself. To achieve the purpose of real-time detection, traditional measuring method, placing a power sensor behind the total-reflection mirror of laser resonant cavity, is mainly applied in the system of gas laser and solid-state laser. However, Owing to the high integration level of diode laser, traditional measuring method can't be adopted. A technique for real-time measure output power of high power diode laser is developed to improve quality of the laser in this paper. A lens placed at an angle of 45° in the system was used to sample output light of laser, and a piece of ground glass was used to uniform the beam power density, then the photoelectric detector received an optic signal and converted it into electric signal. This feeble signal was processed by amplification circuit with a filter. Finally, this detected electric signal was applied to accomplish the closed-loop control of power. The performance of power measurement and control system was tested with the 300W diode laser, and the measuring inaccuracy achieved was less than +/-1%.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Algorithm for Evaluation of Temperature 3D-Distribution of a Vapor Cell in a Diode End-pumped Alkali Laser System

    NASA Astrophysics Data System (ADS)

    Han, J. H.; Wang, Y.; Cai, H.; An, G. F.; Rong, K. P.; Yu, H.; Wang, S. Y.; Wang, H. Y.; Zhang, W.; Xue, L. P.; Zhou, J.

    2017-06-01

    We develop a new 3D-model to evaluate the light characteristics and the thermal features of a cesium-vapor laser end-pumped by a laser diode. The theoretical model is based on the principles of both heat transfer and laser kinetics. The 3-dimensional population density distribution and temperature distribution are both systematically obtained and analyzed. The methodology is thought to be useful for realization of a high-powered diode-pumped alkali laser (DPAL) in the future.

  14. Improved atomic force microscope using a laser diode interferometer

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; Pax, Paul; Yi, Leon; Howells, Sam; Gallagher, Mark; Chen, Ting; Elings, Virgil; Bocek, Dan

    1992-08-01

    The performance of an atomic force microscope using a laser diode interferometer has been improved to the point where its resolution is comparable to that of laser beam deflection systems. We describe the structure of this microscope, present a model that takes into account the main parameters associated with its operation, and demonstrate its sensitivity by showing images of a small area scan with atomic resolution as well as a large area scan in a stand-alone configuration.

  15. A novel 785-nm laser diode-based system for standardization of cell culture irradiation.

    PubMed

    Lins, Emery C; Oliveira, Camila F; Guimarães, Orlando C C; Costa, Carlos A de Souza; Kurachi, Cristina; Bagnato, Vanderlei S

    2013-10-01

    The purpose of this study was to develop a novel device that concatenates alignment of infrared lasers and parallel procedure of irradiation. The purpose of this is to seek standardization of in vitro cell irradiation, which allows analysis and credible comparisons between outcomes of different experiments. Experimental data obtained from infrared laser therapies have been strongly dependent upon the irradiation setup. Although further optical alignment is difficult to achieve, in contact irradiation it usually occurs. Moreover, these methods eventually use laser in a serial procedure, extending the time to irradiate experimental samples. A LASERTable (LT) device was designed to provide similar infrared laser irradiation in 12 wells of a 24 well test plate. It irradiated each well by expanding the laser beam until it covers the well bottom, as occurs with unexpanded irradiation. To evaluate the effectiveness of this device, the spatial distribution of radiation was measured, and the heating of plain culture medium was monitored during the LT operation. The irradiation of LT (up to 25 J/cm(2) - 20 mW/cm(2); 1.250 sec) was assessed on odontoblast-like cells adhered to the bottom of wells containing 1 mL of plain culture medium. Cell morphology and metabolism were also evaluated. Irradiation with LT presented a Gaussian-like profile when the culture medium was not heated >1°C. It was also observed that the LT made it 10 times faster to perform the experiment than did serial laser irradiation. In addition, the data of this study revealed that the odontoblast-like cells exposed to low-level laser therapy (LLLT) using the LT presented higher metabolism and normal morphology. The experimental LASERTable assessed in this study provided parameters for standardization of infrared cell irradiation, minimizing the time spent to irradiate all samples. Therefore, this device is a helpful tool that can be effectively used to evaluate experimental LLLT protocols.

  16. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1987-01-01

    A 25 megabit/sec direct detection optical communication system that used Q=4 PPM signalling was constructed and its performance measured under laboratory conditions. The system used a single-mode AlGaAs laser diode transmitter and low noise silicon avalanche photodiode (APD) photodetector. Comparison of measured performance with the theoretical revealed that modeling the APD output as a Gaussian process under conditions of negligible background radiation and low (less than 10 to the -12 power A) APD bulk leakage currents leads to substantial underestimates of optimal APD gain to use and overestimates of system bit error probability. A procedure is given to numerically compute system performance which uses the more accurate Webb's Approximation of the exact Conradi distribution for the APD ouput signal that does not require excessive amounts of computer time (a few minutes of VAX 8600 CPU time per system operating point). Examples are given which illustrate the breakdown of the Gaussian approximation in assessing system performance. This system achieved a bit error probability of 10 to the -6 power at a received signal energy corresponding to an average of 60 absorbed photons/bit and optimal APD gain of 700.

  17. 54  J pulses with 18  nm bandwidth from a diode-pumped chirped-pulse amplification laser system.

    PubMed

    Hornung, Marco; Liebetrau, Hartmut; Keppler, Sebastian; Kessler, Alexander; Hellwing, Marco; Schorcht, Frank; Becker, Georg A; Reuter, Maria; Polz, Jens; Körner, Jörg; Hein, Joachim; Kaluza, Malte C

    2016-11-15

    We report on results from the fully diode-pumped chirped-pulse amplification laser system Polaris. Pulses were amplified to a maximum energy of 54.2 J before compression. These pulses have a full width at half-maximum spectral bandwidth of 18 nm centered at 1033 nm and are generated at a repetition rate of 0.02 Hz. To the best of our knowledge, these are the most energetic broadband laser pulses generated by a diode-pumped laser system so far. Due to the limited size of our vacuum compressor, only attenuated pulses could be compressed to a duration of 98 fs containing an energy of 16.7 J, which leads to a peak power of 170 TW. These pulses could be focused to a peak intensity of 1.3×1021  W/cm2. Having an ultra-high temporal contrast of 1012 with respect to amplified spontaneous emission these laser pulses are well suited for high-intensity laser-matter experiments.

  18. Power semiconductor laser diode arrays characterization

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Campopiano, Stefania; Cutolo, Antonello; D'Angelo, Giuseppe

    2003-09-01

    Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M2 concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.

  19. Algorithm for evaluation of temperature distribution of a vapor cell in a diode-pumped alkali laser system: part I.

    PubMed

    Han, Juhong; Wang, You; Cai, He; Zhang, Wei; Xue, Liangping; Wang, Hongyuan

    2014-06-02

    A diode-pumped alkali laser (DPAL) is one of the most hopeful candidates to achieve high power performances. As the laser medium is in a gas-state, populations of energy-levels of a DPAL are strongly dependent on the vapor temperature. Thus, the temperature distribution directly determines the output characteristics of a DPAL. In this report, we developed a systematic model by combining the procedures of heat transfer and laser kinetics together to explore the radial temperature distribution in the transverse section of a cesium vapor cell. A cyclic iterative approach is adopted to calculate the population densities. The corresponding temperature distributions have been obtained for different beam waists and pump powers. The conclusion is thought to be useful for realizing a DPAL with high output power.

  20. AlGaAs diode pumped tunable chromium lasers

    DOEpatents

    Krupke, William F.; Payne, Stephen A.

    1992-01-01

    An all-solid-state laser system is disclosed wherein the laser is pumped in the longwave wing of the pump absorption band. By utilizing a laser material that will accept unusually high dopant concentrations without deleterious effects on the crystal lattice one is able to compensate for the decreased cross section in the wing of the absorption band, and the number of pump sources which can be used with such a material increases correspondingly. In a particular embodiment a chromium doped colquiriite-structure crystal such as Cr:LiSrAlF.sub.6 is the laser material. The invention avoids the problems associated with using AlGaInP diodes by doping the Cr:LiSrAlF.sub.6 heavily to enable efficient pumping in the longwave wing of the absorption band with more practical AlGaAs diodes.

  1. Mode stability of external cavity diode lasers.

    PubMed

    Saliba, Sebastian D; Junker, Mark; Turner, Lincoln D; Scholten, Robert E

    2009-12-10

    Mode stability is an important performance characteristic of external cavity diode lasers (ECDLs). It has been well established that the continuous mode-hop-free tuning range of a grating-feedback ECDL can be optimized by rotating the grating about a specific pivot location. We show that similar results can be obtained for other more convenient pivot locations by choosing instead the cavity length and grating location. The relative importance of the temperature stability of the diode and of the external cavity is also evaluated. We show that mechanically simple ECDL designs, using mostly standard components, can readily achieve a 35 GHz mode-hop-free tuning range at 780 nm.

  2. Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen.

    PubMed

    Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang; Eigenbrod, Christian; Klinkov, Konstantin; Larionov, Mikhail; Giesen, Adolf; Stolzenburg, Christian

    2014-03-01

    We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM00) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic around 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.

  3. Diode pumped solid state kilohertz disk laser system for time-resolved combustion diagnostics under microgravity at the drop tower Bremen

    SciTech Connect

    Wagner, Volker; Paa, Wolfgang; Triebel, Wolfgang; Eigenbrod, Christian; Klinkov, Konstantin; Larionov, Mikhail; Giesen, Adolf; Stolzenburg, Christian

    2014-03-15

    We describe a specially designed diode pumped solid state laser system based on the disk laser architecture for combustion diagnostics under microgravity (μg) conditions at the drop tower in Bremen. The two-stage oscillator-amplifier-system provides an excellent beam profile (TEM{sub 00}) at narrowband operation (Δλ < 1 pm) and is tunable from 1018 nm to 1052 nm. The laser repetition rate of up to 4 kHz at pulse durations of 10 ns enables the tracking of processes on a millisecond time scale. Depending on the specific issue it is possible to convert the output radiation up to the fourth harmonic around 257 nm. The very compact laser system is integrated in a slightly modified drop capsule and withstands decelerations of up to 50 g (>11 ms). At first the concept of the two-stage disk laser is briefly explained, followed by a detailed description of the disk laser adaption to the drop tower requirements with special focus on the intended use under μg conditions. In order to demonstrate the capabilities of the capsule laser as a tool for μg combustion diagnostics, we finally present an investigation of the precursor-reactions before the droplet ignition using 2D imaging of the Laser Induced Fluorescence of formaldehyde.

  4. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    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.

  5. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    NASA Technical Reports Server (NTRS)

    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.

  6. A Novel 785-nm Laser Diode-Based System for Standardization of Cell Culture Irradiation

    PubMed Central

    Oliveira, Camila F.; Guimarães, Orlando C.C.; Costa, Carlos A. de Souza; Kurachi, Cristina; Bagnato, Vanderlei S.

    2013-01-01

    Abstract Objective: The purpose of this study was to develop a novel device that concatenates alignment of infrared lasers and parallel procedure of irradiation. The purpose of this is to seek standardization of in vitro cell irradiation, which allows analysis and credible comparisons between outcomes of different experiments. Background data: Experimental data obtained from infrared laser therapies have been strongly dependent upon the irradiation setup. Although further optical alignment is difficult to achieve, in contact irradiation it usually occurs. Moreover, these methods eventually use laser in a serial procedure, extending the time to irradiate experimental samples. Methods: A LASERTable (LT) device was designed to provide similar infrared laser irradiation in 12 wells of a 24 well test plate. It irradiated each well by expanding the laser beam until it covers the well bottom, as occurs with unexpanded irradiation. To evaluate the effectiveness of this device, the spatial distribution of radiation was measured, and the heating of plain culture medium was monitored during the LT operation. The irradiation of LT (up to 25 J/cm2 – 20 mW/cm2; 1.250 sec) was assessed on odontoblast-like cells adhered to the bottom of wells containing 1 mL of plain culture medium. Cell morphology and metabolism were also evaluated. Results: Irradiation with LT presented a Gaussian-like profile when the culture medium was not heated >1°C. It was also observed that the LT made it 10 times faster to perform the experiment than did serial laser irradiation. In addition, the data of this study revealed that the odontoblast-like cells exposed to low-level laser therapy (LLLT) using the LT presented higher metabolism and normal morphology. Conclusions: The experimental LASERTable assessed in this study provided parameters for standardization of infrared cell irradiation, minimizing the time spent to irradiate all samples. Therefore, this device is a helpful tool that can be

  7. Optomechanical design of the grating laser beam combiner (GLBC) laser diode header

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1989-01-01

    A laser diode header has been fabricated for a grating laser beam combiner (GLBC). The laser diode header provides the thermal control, the drive electronics, and the optical system necessary for proper operation of the beam combiner. The diode header is required to provide diffraction limited optical performance while providing correction for worst case defocus aberration, 0.6 mrad excess divergence, and worst case decenter aberration, 1.0 mrad pointing error. The design of the header considered the mechanical design and the optical design together resulting in a small, self-contained header with 0.7 mrad range for focus correction and +/- 2.5 mrad of beam steering. The complete diode header is currently undergoing optical and mechanical performance testing.

  8. Small core fiber coupled 60-W laser diode

    NASA Astrophysics Data System (ADS)

    Fernie, Douglas P.; Mannonen, Ilkka; Raven, Anthony L.

    1995-05-01

    Semiconductor laser diodes are compact, efficient and reliable sources of laser light and 25 W fiber coupled systems developed by Diomed have been in clinical use for over three years. For certain applications, particularly in the treatment of benign prostatic hyperplasia and flexible endoscopy, higher powers are desirable. In these applications the use of flexible optical fibers of no more than 600 micrometers core diameter is essential for compatibility with most commercial delivery fibers and instrumentation. A high power 60 W diode laser system for driving these small core fibers has been developed. The design requirements for medical applications are analyzed and system performance and results of use in gastroenterology and urology with small core fibers will be presented.

  9. High-brightness, high-power 9xx-nm diode laser bars: developments at JENOPTIK diode lab

    NASA Astrophysics Data System (ADS)

    Sebastian, J.; Schulze, H.; Hülsewede, R.; Hennig, P.; Meusel, J.; Schröder, M.; Schröder, D.; Lorenzen, D.

    2007-02-01

    We report present advantages of high power 9xxnm diode laser bars for pumping of disc laser and especially for pumping fibre lasers and amplifiers. The strong demand for reduce system costs needs to have a good compromise in improved diode laser power, conversion efficiency, reliability and beam quality leading to simplified system designs. Basis of the new generation for the 9xxnm laser diode bars at JENOPTIK Diode Lab is a low loss wave guide AlGaAs - structure with low vertical far field angle of 27° (FWHM). Recently we demonstrate an output power in excess of 500W in CW operation from a diode laser bar with 50% filling factor and 3.0mm cavity length. This record was possible due to high power conversion efficiency of >68 %, optimised facet coating technology and an excellent active cooling. New results on conductive cooled high brightness laser bars of 20% filling factor with special emphasis to the needs of high efficiency fibre coupling will be presented. Lifetime tests under long pulse conditions have demonstrated a very high reliability for 120 W laser bars with 50 % filling factor and for 60 W laser bars with 20 % and 30 % filling factor.

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

    EPA Science Inventory

    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. ...

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

    EPA Science Inventory

    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. ...

  12. Chirped microlens arrays for diode laser circularization and beam expansion

    NASA Astrophysics Data System (ADS)

    Schreiber, Peter; Dannberg, Peter; Hoefer, Bernd; Beckert, Erik

    2005-08-01

    Single-mode diode lasers are well-established light sources for a huge number of applications but suffer from astigmatism, beam ellipticity and large manufacturing tolerances of beam parameters. To compensate for these shortcomings, various approaches like anamorphic prism pairs and cylindrical telescopes for circularization as well as variable beam expanders based on zoomed telescopes for precise adjustment of output beam parameters have been employed in the past. The presented new approach for both beam circularization and expansion is based on the use of microlens arrays with chirped focal length: Selection of lenslets of crossed cylindrical microlens arrays as part of an anamorphic telescope enables circularization, astigmatism correction and divergence tolerance compensation of diode lasers simultaneously. Another promising application of chirped spherical lens array telescopes is stepwise variable beam expansion for circular laser beams of fiber or solid-state lasers. In this article we describe design and manufacturing of beam shaping systems with chirped microlens arrays fabricated by polymer-on-glass replication of reflow lenses. A miniaturized diode laser module with beam circularization and astigmatism correction assembled on a structured ceramics motherboard and a modulated RGB laser-source for photofinishing applications equipped with both cylindrical and spherical chirped lens arrays demonstrate the feasibility of the proposed system design approach.

  13. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1988-01-01

    Slot timing recovery in a direct detection optical PPM communication system can be achieved by processing the photodetector waveform with a nonlinear device whose output forms the input to a phase lock group. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (lambda = 834 nm) and a silicon avalanche photodiode (APD) photodetector and used Q=4 PPM signaling operated at a source data rate of 25 megabits/second. The mathematical model developed to characterize system performance is shown to be in good agreement with actual performance measurements. The use of the recovered slot clock in the receiver resulted in no degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the minus 6 power at received signal energies corresponding to an average of less than 60 detected photons per information bit.

  14. Low level diode laser accelerates wound healing.

    PubMed

    Dawood, Munqith S; Salman, Saif Dawood

    2013-05-01

    The effect of wound illumination time by pulsed diode laser on the wound healing process was studied in this paper. For this purpose, the original electronic drive circuit of a 650-nm wavelength CW diode laser was reconstructed to give pulsed output laser of 50 % duty cycle and 1 MHz pulse repetition frequency. Twenty male mice, 3 months old were used to follow up the laser photobiostimulation effect on the wound healing progress. They were subdivided into two groups and then the wounds were made on the bilateral back sides of each mouse. Two sessions of pulsed laser therapy were carried along 15 days. Each mice group wounds were illuminated by this pulsed laser for 12 or 18 min per session during these 12 days. The results of this study were compared with the results of our previous wound healing therapy study by using the same type of laser. The mice wounds in that study received only 5 min of illumination time therapy in the first and second days of healing process. In this study, we found that the wounds, which were illuminated for 12 min/session healed in about 3 days earlier than those which were illuminated for 18 min/session. Both of them were healed earlier in about 10-11 days than the control group did.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  16. Diode pumped distributed Bragg reflector lasers based on a dye-to-polymer energy transfer blend.

    PubMed

    Vasdekis, A E; Tsiminis, G; Ribierre, J-C; O' Faolain, Liam; Krauss, T F; Turnbull, G A; Samuel, I D W

    2006-10-02

    We report the demonstration of a compact, all-solid-state polymer laser system comprising of a Gallium Nitride (GaN) semiconductor diode laser as the pump source. The polymer laser was configured as a surface emitting, distributed Bragg reflector laser (DBR), based on a novel energy transfer blend of Coumarin 102 and the conjugated polymer poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene). In this configuration, diode pumping was possible both due to the improved quality of the resonators and the improved harvesting of the diode laser light.

  17. WDM Nanoscale Laser Diodes for Si Photonic Interconnects

    DTIC Science & Technology

    2016-07-25

    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...Distribution Unlimited UU UU UU UU 25-07-2016 1-Feb-2012 31-Dec-2015 Final Report: WDM Nanoscale Laser Diodes for Si Photonic Interconnects The views...P.O. Box 12211 Research Triangle Park, NC 27709-2211 VCSEL, optical interconnect, laser diode , semiconductor laser, microcavity REPORT DOCUMENTATION

  18. VCSEL's frequency stabilization of an external cavity diode laser: countermeasures against atmospheric temperature variations

    NASA Astrophysics Data System (ADS)

    Motojima, Mutsuki; Doi, Kohei; Sato, Takashi; Ohkawa, Masashi; Suzuki, Takamasa

    2010-02-01

    We introduced the vertical cavity surface emitting laser (VCSEL) as the laser diode in tour external cavity system. Because VCSELs are now commercially available, and the External cavity diode laser (ECDL) systems using them are expected to improve their frequency stability, we have replaced a Fabry-Perot type laser diode with a VCSEL, and examined its oscillation-frequency stability. Therefore we were able to expect that the VCSELs with our double optical feedback system have good oscillation frequency stability. The obtained VCSEL's oscillation-frequency stability, i.e., the square root of Allan variance σ was 4×10-10, at an averaging time of τ=1 sec.

  19. Modeling the brain with laser diodes

    NASA Astrophysics Data System (ADS)

    McAulay, Alastair D.

    2007-09-01

    The Wilson-Cowan mathematical model is popular for representing a neuron in the brain and may be viewed as two cross-coupled dynamical nonlinear neural networks, one excitatory and one inhibitory. This gives rise to two coupled first order equations. Varying an input parameter, the sum of input intensities from all other incoming neurons, causes the Wilson-Cowan neural oscillator to move through a supercritical Hopf bifurcation so as to switch its output from a stable-off when the input is below a firing threshold to a stable-oscillation (limit cycle) for signals above the threshold; the frequency of which depends on the level of input stimulation. The use of frequency to represent pulse rate makes the brain robust against electromagnetic interference and drift. We show that the laser diode rate equations for a single optically injected laser diode can also be modeled by two coupled first order equations that give rise to supercritical Hopf bifurcations. But the laser rate equations have a complex variable where that for the Wilson-Cowan model equations is real. By using the real part of the complex variable (a projection onto the real plane), the optically injected laser diode can exactly simulate the movement through supercritical Hopf bifurcation of the Wilson-Cowan equations by varying the amplitude and frequency of the optical injection.

  20. Integrated software package for laser diodes characterization

    NASA Astrophysics Data System (ADS)

    Sporea, Dan G.; Sporea, Radu A.

    2003-10-01

    The characteristics of laser diodes (wavelength of the emitted radiation, output optical power, embedded photodiode photocurrent, threshold current, serial resistance, external quantum efficiency) are strongly influenced by their driving circumstances (forward current, case temperature). In order to handle such a complex investigation in an efficient and objective manner, the operation of several instruments (a laser diode driver, a temperature controller, a wavelength meter, a power meter, and a laser beam analyzer) is synchronously controlled by a PC, through serial and GPIB communication. For each equipment, instruments drivers were designed using the industry standards graphical programming environment - LabVIEW from National Instruments. All the developed virtual instruments operate under the supervision of a managing virtual instrument, which sets the driving parameters for each unit under test. The manager virtual instrument scans as appropriate the driving current and case temperature values for the selected laser diode. The software enables data saving in Excel compatible files. In this way, sets of curves can be produced according to the testing cycle needs.

  1. Method and system for communicating with a laser power driver

    DOEpatents

    Telford, Steven

    2017-07-18

    A system for controlling a plurality of laser diodes includes an optical transmitter coupled to the laser diode driver for each laser diode. An optical signal including bi-phase encoded data is provided to each laser diode driver. The optical signal includes current level and pulse duration information at which each of the diodes is to be driven. Upon receiving a trigger signal, the laser diode drivers operate the laser diodes using the current level and pulse duration information to output a laser beam.

  2. Plasma formation in diode pumped alkali lasers sustained in Cs

    NASA Astrophysics Data System (ADS)

    Markosyan, Aram H.; Kushner, Mark J.

    2016-11-01

    In diode pumped alkali lasers (DPALs), lasing action occurs on the resonant lines of alkali atoms following pumping by broadband semiconductor lasers. The goal is to convert the efficient but usually poor optical quality of inexpensive diode lasers into the high optical quality of atomic vapor lasers. Resonant excitation of alkali vapor leads to plasma formation through the excitation transfer from the 2P states to upper lying states, which then are photoionized by the pump and intracavity radiation. A first principles global model was developed to investigate the operation of the He/Cs DPAL system and the consequences of plasma formation on the efficiency of the laser. Over a range of pump powers, cell temperatures, excitation frequency, and mole fraction of the collision mixing agent (N2 or C2H6), we found that sufficient plasma formation can occur that the Cs vapor is depleted. Although N2 is not a favored collisional mixing agent due to large rates of quenching of the 2P states, we found a range of pump parameters where laser oscillation may occur. The poor performance of N2 buffered systems may be explained in part by plasma formation. We found that during the operation of the DPAL system with N2 as the collisional mixing agent, plasma formation is in excess of 1014-1015 cm-3, which can degrade laser output intensity by both depletion of the neutral vapor and electron collisional mixing of the laser levels.

  3. Proton displacement damage in light-emitting and laser diodes

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.

    2000-01-01

    The effects of proton displacement damage on light-emitting diodes and laser diodes are discussed, comparing the radiation sensitivity of current technology devices with older devices for which data exists in the literature.

  4. Diode laser welding of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-01

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  5. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-04

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  6. Utilization of pulsed diode lasers to lidar remote sensing

    NASA Astrophysics Data System (ADS)

    Penchev, S.; Pencheva, Vasilka H.; Naboko, Vassily N.; Naboko, Sergei V.; Simeonov, P.

    2001-04-01

    Investigation of new aspects of application of pulsed quantum well (In)GaAs/AlGaAs diode lasers to atmospheric spectroscopy and lidar remote sensing is reported. The presented method utilizing these powerful multichipstack diode lasers of broad radiation line is approved theoretically and experimentally for monitoring of atmospheric humidity. Molecular absorption of gas species in the investigated spectral band 0.85 - 0.9 micrometer implemented by laser technology initiates further development of prospective DIAL analysis. A mobile lidar system is realized, employing optimal photodetection based on computer-operated boxcar and adaptive digital filter processing of the lidar signal in the analytical system. Aerosol profile exhibiting cloud strata in open atmosphere by testing of the sensor is demonstrative of the efficiency and high sensitivity of long-range sounding.

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

    DOEpatents

    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.

  8. Active alignment and reliable pigtailing of laser diode transmitter

    NASA Astrophysics Data System (ADS)

    Fadhali, M.; Saktioto, .; Zainal, J.; Munajat, Y.; Ali, J.; Rahman, R.

    2008-09-01

    In this paper we present theoretical and experimental analysis on Nd:YAG laser microwelding for pigtailing laser diode transmitter through two ball lenses that are employed for effectively matching the elliptical mode field of the laser diode with the circular on of the single mode fiber. The fiber attachment and the fixing of various coupling components have been performed in what is so called active alignment process. The system continues measuring the coupled power during the processes of alignment and attachment of various coupling components as well as the working distance and misalignment tolerances optimizations. Results of theoretical modeling of laser weld penetration depth agree with the experimentally measured results in the low laser pulse energy range. Moreover the laser pulse parameters such as, duration, energy, number of pulse shoots as well as the focusing position over the workpiece and angle of laser pulse incidence are found to have very significant effects on the weld yields and greatly affect the laser weld depth to width ratio. Optimization of all the mentioned parameters found to be necessary for achieving strong laser microwelds with more penetration and less width in the attachments of the sensitive optical components inside the packaged photonic devices modules.

  9. High power diode lasers for solid-state laser pumps

    NASA Astrophysics Data System (ADS)

    Linden, Kurt J.; McDonnell, Patrick N.

    1994-02-01

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

  10. High power diode lasers for solid-state laser pumps

    NASA Technical Reports Server (NTRS)

    Linden, Kurt J.; Mcdonnell, Patrick N.

    1994-01-01

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

  11. Diode laser welding of high yield steel

    NASA Astrophysics Data System (ADS)

    Lisiecki, Aleksander

    2013-01-01

    The following article describes results of investigations on influence of laser welding parameters on the weld shape, quality and mechanical properties of 2.5 mm thick butt joints of thermo-mechanically rolled, high yield strength steel for cold forming S420MC (according to EN 10149 - 3 and 060XLK according to ASTM) welded with high power diode laser HPDL ROFIN SINAR DL 020 with rectangular laser beam spot and 2.2 kW output power, and 808 nm wavelength. The investigations at the initial stage were focused on detailed analysis of influence of the basic laser welding parameters such as laser power and welding speed on the shape and quality of single bead produced during bead-on-plate welding. Then the optimal parameters were chosen for laser welding of 2.5 mm thick butt joints of the thermo-mechanically rolled, high yield strength steel sheets for cold forming S420MC. The test joints were prepared as single square groove and one-side laser welded without an additional material, at a flat position. Edges of steel sheets were melted in argon atmosphere by the laser beam focused on the top joint surface. The test welded joints were investigated by visual inspection, metallographic examinations, mechanical tests such as tensile tests and bending tests. It was found that the high power diode laser may be applied successfully for one-side welding of the S420MC steel butt joints. Additionally it was found that in the optimal range of laser welding parameters the high quality joint were produced.

  12. A new diode laser acupuncture therapy apparatus

    NASA Astrophysics Data System (ADS)

    Li, Chengwei; Huang, Zhen; Li, Dongyu; Zhang, Xiaoyuan

    2006-06-01

    Since the first laser-needles acupuncture apparatus was introduced in therapy, this kind of apparatus has been well used in laser biomedicine as its non-invasive, pain- free, non-bacterium, and safetool. The laser acupuncture apparatus in this paper is based on single-chip microcomputer and associated by semiconductor laser technology. The function like traditional moxibustion including reinforcing and reducing is implemented by applying chaos method to control the duty cycle of moxibustion signal, and the traditional lifting and thrusting of acupuncture is implemented by changing power output of the diode laser. The radiator element of diode laser is made and the drive circuit is designed. And chaos mathematic model is used to produce deterministic class stochastic signal to avoid the body adaptability. This function covers the shortages of continuous irradiation or that of simple disciplinary stimulate signal, which is controlled by some simple electronic circuit and become easily adjusted by human body. The realization of reinforcing and reducing of moxibustion is technological innovation in traditional acupuncture coming true in engineering.

  13. Tunable-diode laser absorption spectrometry

    NASA Technical Reports Server (NTRS)

    Schiff, H. I.

    1986-01-01

    Tunable-diode laser absorption spectrometry (TDLAS) affords a number of advantages for atmospheric measurements. It is a universal method, applicable, in principle, to all gases of atmospheric interest. Because of its extremely high spectral resolution it provides unequivocal identification of the target species, with no interferences from other gases. It provides real-time, in situ measurements with time resolutions better than 1 minute. The sensitivity of the current TDLAS system is marginally capable of measuring HO2. This species exists in the troposphere at concentrations which are up to 2 orders of magnitude higher than those of HO and, in addition, is much less susceptible to removal by the surfaces of the instrument and its sampling system. HO2 is an important HO sub x species in its own right but can also give direct information on the HO concentration by virtue of the rapid partitioning between these two species. The addition of the high-frequency modulation technique to the TDLAS system would ensure its ability to measure HO2 under most atmospheric conditions. The ability of the TDLAS to measure hydrogen peroxide (H2O2) in the ambient atmosphere was also demonstrated. H2O2 measurements give a clear indication of HO sub x mixing ratios and are also important as a photolytic source of HO and as an important oxidant for other atmospheric consitituents such as SO2.

  14. Modeling of diode pumped nanoparticle gas laser

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Wang, Hongyan; Yang, Zining; Xu, Xiaojun

    2017-05-01

    The hybrid gas phase and solid state laser shows its inherent advantages in heat management and high efficiency and compactness, with DPAL becoming a perfect example. However, this kind of laser is limited by concern, for example, narrow absorption linewidth and a series of problems resulting from chemical reactions. As a matter of fact, Prof. Krupke proposed some hybrid gas phase and solid state lasers before DPAL, while they were chemically unfavored. As a newest type of hybrid gas phase and solid state laser, diode pumped nanoparticle gas laser (DPNGL) is a potential candidate in high power laser field. We put forward a rate equation model for Yb3+ doped nanoparticle gas laser, and scattering of nanoparticles at the nano scale is included in this model. In addition, modifications of fluorescence lifetime and laser emission and pump absorption cross section are coupled into this model. Some vital factors are simulated and discussed. The results obtained from the modeling show that the influence of scattering is weak, and the Yb3+ concentration is not necessarily high to achieve a good laser performance. The results are sufficiently positive for DPNGL to be a promising high power laser.

  15. Two-beam combined 3.36  J, 100  Hz diode-pumped high beam quality Nd:YAG laser system.

    PubMed

    Qiu, J S; Tang, X X; Fan, Z W; Wang, H C; Liu, H

    2016-07-20

    In this paper, we develop a diode-pumped all-solid-state high-energy and high beam quality Nd:YAG laser system. A master oscillator power amplifier structure is used to provide a high pulse energy laser output with a high repetition rate. In order to decrease the amplifier working current so as to reduce the impact of the thermal effect on the beam quality, a beam splitting-amplifying-combining scheme is adopted. The energy extraction efficiency of the laser system is 50.68%. We achieve 3.36 J pulse energy at a 100 Hz repetition rate with a pulse duration of 7.1 ns, a far-field beam spot 1.71 times the diffraction limit, and 1.07% energy stability (RMS).

  16. InGaN-BASED Laser Diodes

    NASA Astrophysics Data System (ADS)

    Nakamura, Shuji

    1998-08-01

    Continuous-wave operation of InGaN multi-quantum-well (MQW) structure laser diodes (LDs) has been demonstrated at room temperature with output power up to 50 mW, operating temperature up to 100oC, emission wavelength of 400-420 nm, and a lifetime up to 300 h. InGaN MQW LDs with a lifetime of more than 1000 h are expected soon. Commercialization will begin in 1998 if research on the bluish-purple InGaN-based laser diodes continues to progress. The stimulated emission of the InGaN-based LDs originates from localized energy states of 100-250 meV depth, which are equivalent to quantum dot energy states, probably arising from from InGaN composition fluctuation in the InGaN well layers.

  17. Interferometric investigation of a diode laser source

    SciTech Connect

    Creath, K.

    1985-05-01

    Diode lasers provide a coherent light source in the near IR. They have many desirable characteristics such as small size, high efficiency, a single-longitudinal mode output as large as 15 mW, and can be modulated at high pulse rates. An AlGaAs diode laser operating at 840 nm with an output of 5 mW was evaluated with a Smartt point diffraction interferometer. The wave front observed had astigmatism of approx.2 lambda present over the output beam divergence angle. In a modified Twyman-Green interferometer, the coherence length measured was >15 m with high visibility fringes. This source was found to be stable and highly linearly polarized. When used as an interferometric source, many possibilities for small scale interferometers and test equipment are now viable.

  18. Evaluation of a satellite laser ranging technique using pseudonoise code modulated laser diodes

    NASA Technical Reports Server (NTRS)

    Ball, Carolyn Kay

    1987-01-01

    Several types of Satellite Laser Ranging systems exist, operating with pulsed, high-energy lasers. The distance between a ground point and an orbiting satellite can be determined to within a few centimeters. A new technique substitutes pseudonoise code modulated laser diodes, which are much more compact, reliable and less costly, for the lasers now used. Since laser diode technology is only now achieving sufficiently powerful lasers, the capabilities of the new technique are investigated. Also examined are the effects of using an avalanche photodiode detector instead of a photomultiplier tube. The influence of noise terms (including background radiation, detector dark and thermal noise and speckle) that limit the system range and performance is evaluated.

  19. Diode Laser Sensor for Scramjet Inlet

    DTIC Science & Technology

    2010-05-11

    Conference’. 1.2 O’Byrne, S., Huynh, L., Wittig, S. M. and Smith, N. S. A. (2009), Non- intrusive water vapour absorp- tion measurements in a simulated...O’Byrne, L. Huynh, S. M. Wittig and N. S. A. Smith, “Non- intrusive Water Vapour Absorp- tion Measurements in a Simulated Helicopter Exhaust”, Proceedings...rather than at a surface. The measurement techniques used at these hypersonic flow conditions should also be non- intrusive . Tuneable diode laser

  20. Wavelength Beam-Combined Laser Diode Arrays

    DTIC Science & Technology

    2012-01-01

    focal length f f f Diffraction grating Output...lead Water in/out Figure 3. Lincoln Laboratory-designed WBC “laser in a box.” To reduce the overall size of the WBC device, multiple folding mirrors were implemented between the diode array and the concave mirror . ...spatially merges multiple wave- length sources into a single high-inten- sity beam with an order-of-magnitude improvement in brightness compared

  1. Advancements in flowing diode pumped alkali lasers

    NASA Astrophysics Data System (ADS)

    Pitz, Greg A.; Stalnaker, Donald M.; Guild, Eric M.; Oliker, Benjamin Q.; Moran, Paul J.; Townsend, Steven W.; Hostutler, David A.

    2016-03-01

    Multiple variants of the Diode Pumped Alkali Laser (DPAL) have recently been demonstrated at the Air Force Research Laboratory (AFRL). Highlights of this ongoing research effort include: a) a 571W rubidium (Rb) based Master Oscillator Power Amplifier (MOPA) with a gain (2α) of 0.48 cm-1, b) a rubidium-cesium (Cs) Multi-Alkali Multi-Line (MAML) laser that simultaneously lases at both 795 nm and 895 nm, and c) a 1.5 kW resonantly pumped potassium (K) DPAL with a slope efficiency of 50%. The common factor among these experiments is the use of a flowing alkali test bed.

  2. Space Qualification of Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Troupaki, Elisavet; Kashem, Nasir B.; Allan, Graham R.; Vasilyev, Aleksey; Stephen, Mark

    2005-01-01

    Laser instruments have great potential in enabling a new generation of remote-sensing scientific instruments. NASA s desire to employ laser instruments aboard satellites, imposes stringent reliability requirements under severe conditions. As a result of these requirements, NASA has a research program to understand, quantify and reduce the risk of failure to these instruments when deployed on satellites. Most of NASA s proposed laser missions have base-lined diode-pumped Nd:YAG lasers that generally use quasi-constant wave (QCW), 808 nm Laser Diode Arrays (LDAs). Our group has an on-going test program to measure the performance of these LDAs when operated in conditions replicating launch and orbit. In this paper, we report on the results of tests designed to measure the effect of vibration loads simulating launch into space and the radiation environment encountered on orbit. Our primary objective is to quantify the performance of the LDAs in conditions replicating those of a satellite instrument, determine their limitations and strengths which will enable better and more robust designs. To this end we have developed a systematic testing strategy to quantify the effect of environmental stresses on the optical and electrical properties of the LDA.

  3. Highly efficient multimode diode-pumped Yb:KYW laser

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. A.; Pivtsov, V. S.; Semenko, A. V.; Bagayev, S. N.

    2017-01-01

    Record high differential efficiency (53.2%) and full optical efficiency (48%) for a multimode diode-pumped Yb:KYW laser have been achieved. The characteristics of the laser and methods for improving its efficiency using a distributed Bragg reflector tapered diode laser (DBR TDL) are discussed.

  4. A Comparative Study of Enamel Surface Roughness After Bleaching With Diode Laser and Nd: YAG Laser.

    PubMed

    Mirzaie, Mansoreh; Yassini, Esmaiel; Ganji, Saber; Moradi, Zohreh; Chiniforush, Nasim

    2016-01-01

    Introduction: Bleaching process can affect surface roughness of enamel, which is a vital factor in esthetic and resistance of tooth. The aim of this study was to compare surface roughness of enamel in teeth bleached using Diode and Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) lasers with those bleached using conventional method. Methods: In this study, 75 anterior human teeth from upper and lower jaws (These teeth extracted because of periodontal disease) were randomly divided into 5 groups. Group 1: Laser white gel (Biolase, USA) with 45% hydrogen peroxide concentration and GaAlAs Diode laser (CHEESE(TM), GIGAA, China), group 2: Heydent gel (JW, Germany) with 30% Hydrogen peroxide concentration and Diode laser, group 3: Laser white gel and Nd:YAG laser (FIDELIS(TM), Fotona, Slovenia), group 4: Heydent gel and Nd:YAG laser and group 5: The Iranian gel Kimia (Iran) with 35% hydrogen peroxide concentration were used. Surface roughness of the samples was measured using the Surface Roughness Tester system (TR 200 Time Group, Germany) before and after bleaching. In each group, one sample was randomly selected for SEM analysis. Results: The results showed that the mean surface roughness of the teeth before and after bleaching had a significant difference in all the study groups. It was indicated that after bleaching, the mean surface roughness had increased in all the study groups. The highest surface roughness was seen in the conventional bleaching group and the lowest surface roughness was reported in group 3 (laser white gel + diode laser), in which the average surface roughness increased by only 0.1 μm. Conclusion: It was concluded that using the Laser white gel and the diode laser for bleaching resulted in the least surface roughness compared to conventional method.

  5. A Comparative Study of Enamel Surface Roughness After Bleaching With Diode Laser and Nd: YAG Laser

    PubMed Central

    Mirzaie, Mansoreh; Yassini, Esmaiel; Ganji, Saber; Moradi, Zohreh; Chiniforush, Nasim

    2016-01-01

    Introduction: Bleaching process can affect surface roughness of enamel, which is a vital factor in esthetic and resistance of tooth. The aim of this study was to compare surface roughness of enamel in teeth bleached using Diode and Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) lasers with those bleached using conventional method. Methods: In this study, 75 anterior human teeth from upper and lower jaws (These teeth extracted because of periodontal disease) were randomly divided into 5 groups. Group 1: Laser white gel (Biolase, USA) with 45% hydrogen peroxide concentration and GaAlAs Diode laser (CHEESETM, GIGAA, China), group 2: Heydent gel (JW, Germany) with 30% Hydrogen peroxide concentration and Diode laser, group 3: Laser white gel and Nd:YAG laser (FIDELISTM, Fotona, Slovenia), group 4: Heydent gel and Nd:YAG laser and group 5: The Iranian gel Kimia (Iran) with 35% hydrogen peroxide concentration were used. Surface roughness of the samples was measured using the Surface Roughness Tester system (TR 200 Time Group, Germany) before and after bleaching. In each group, one sample was randomly selected for SEM analysis. Results: The results showed that the mean surface roughness of the teeth before and after bleaching had a significant difference in all the study groups. It was indicated that after bleaching, the mean surface roughness had increased in all the study groups. The highest surface roughness was seen in the conventional bleaching group and the lowest surface roughness was reported in group 3 (laser white gel + diode laser), in which the average surface roughness increased by only 0.1 μm. Conclusion: It was concluded that using the Laser white gel and the diode laser for bleaching resulted in the least surface roughness compared to conventional method. PMID:28144442

  6. Low-cost laser diode array

    DOEpatents

    Freitas, Barry L.; Skidmore, Jay A.

    1999-01-01

    A substrate is used to fabricate a low-cost laser diode array. A substrate is machined from an electrically insulative material that is thermally conductive, or two substrates can be bonded together in which the top substrate is electrically as well as thermally conductive. The substrate thickness is slightly longer than the cavity length, and the width of the groove is wide enough to contain a bar and spring (which secures the laser bar firmly along one face of the groove). The spring also provides electrical continuity from the backside of the bar to the adjacent metalization layer on the laser bar substrate. Arrays containing one or more bars can be formed by creating many grooves at various spacings. Along the groove, many bars can be adjoined at the edges to provide parallel electrical conduction. This architecture allows precise and predictable registration of an array of laser bars to a self-aligned microlens array at low cost.

  7. Low-cost laser diode array

    DOEpatents

    Freitas, B.L.; Skidmore, J.A.

    1999-06-01

    A substrate is used to fabricate a low-cost laser diode array. A substrate is machined from an electrically insulative material that is thermally conductive, or two substrates can be bonded together in which the top substrate is electrically as well as thermally conductive. The substrate thickness is slightly longer than the cavity length, and the width of the groove is wide enough to contain a bar and spring (which secures the laser bar firmly along one face of the groove). The spring also provides electrical continuity from the backside of the bar to the adjacent metalization layer on the laser bar substrate. Arrays containing one or more bars can be formed by creating many grooves at various spacings. Along the groove, many bars can be adjoined at the edges to provide parallel electrical conduction. This architecture allows precise and predictable registration of an array of laser bars to a self-aligned microlens array at low cost. 19 figs.

  8. New Submount Requirement of Conductively Cooled Laser Diodes for Lidar Applications

    NASA Technical Reports Server (NTRS)

    Mo, S. Y.; Cutler, A. D.; Choi, S. H.; Lee, M. H.; Singh, U. N.

    2000-01-01

    New submount technology is essential for the development of conductively cooled high power diode laser. The simulation and experimental results indicate that thermal conductivity of submount for high power laser-diode must be at least 600 W/m/k or higher for stable operation. We have simulated several theoretical thermal model based on new submount designs and characterized high power diode lasers to determine temperature effects on the performances of laser diodes. The characterization system measures the beam power, output beam profile, temperature distribution, and spectroscopic property of high power diode laser. The characterization system is composed of four main parts: an infrared imaging camera, a CCD camera, a monochromator, and a power meter. Thermal characteristics of two commercial-grade CW 20-W diode laser bars with open heat-sink type were determined with respect to the line shift of emission spectra and beam power stability. The center wavelength of laser emission has a tendency to shift toward longer wavelength as the driving current and heat sink temperature are increased. The increase of heat sink temperature decreases the output power of the laser bar too. Such results lay the guidelines for the design of new submount for high power laser-diodes.

  9. New Submount Requirement of Conductively Cooled Laser Diodes for Lidar Applications

    NASA Technical Reports Server (NTRS)

    Mo, S. Y.; Cutler, A. D.; Choi, S. H.; Lee, M. H.; Singh, U. N.

    2000-01-01

    New submount technology is essential for the development of conductively cooled high power diode laser. The simulation and experimental results indicate that thermal conductivity of submount for high power laser-diode must be at least 600 W/m/k or higher for stable operation. We have simulated several theoretical thermal model based on new submount designs and characterized high power diode lasers to determine temperature effects on the performances of laser diodes. The characterization system measures the beam power, output beam profile, temperature distribution, and spectroscopic property of high power diode laser. The characterization system is composed of four main parts: an infrared imaging camera, a CCD camera, a monochromator, and a power meter. Thermal characteristics of two commercial-grade CW 20-W diode laser bars with open heat-sink type were determined with respect to the line shift of emission spectra and beam power stability. The center wavelength of laser emission has a tendency to shift toward longer wavelength as the driving current and heat sink temperature are increased. The increase of heat sink temperature decreases the output power of the laser bar too. Such results lay the guidelines for the design of new submount for high power laser-diodes.

  10. Efficient high-brightness diode laser modules offer new industrial applications

    NASA Astrophysics Data System (ADS)

    Revermann, Markus; Timmermann, Andre; Meinschien, Jens; Bruns, Peter

    2007-02-01

    We present new developed high power diode laser modules which are performing at outstanding brightness and their applications. The combination of recently designed laser diode bars on passive heat sinks and optimized micro-optics results to laser modules up to 50W out of a 100μm fibre with a 0.22 NA at one single wavelength based on broad area laser bars (BALB) and up to 50W out of 50μm fibre with a 0.22 NA based on single-mode emitter array laser (SEAL) bars. The fibre coupled systems are based on diode lasers with a collimated beam of superior beam data, namely < 10 mm x 10 mm beam diameter (FW1/e2) and < 2mrad x 2mrad divergence (FW1/e2). Such free beam diode lasers deliver 30 W or 60 W output power. The applications for such laser diode modules varies from direct marking, cutting and welding of metals and other materials up to pumping of fibre lasers and amplifiers. Marking speed with up to 30mm/s on stainless steel was observed with 20W laser power and 50μm fibre with a conventional marking setup. Cutting speed of about 1m/min of 0.2mm Kovar sheet was shown with a diode laser module with 50W laser power from a 100μm fibre.

  11. Diode Laser Measurements of Concentration and Temperature in Microgravity Combustion

    NASA Technical Reports Server (NTRS)

    Silver, Joel A.; Kane, Daniel J.

    1999-01-01

    Diode laser absorption spectroscopy provides a direct method of determinating species concentration and local gas temperature in combustion flames. Under microgravity conditions, diode lasers are particularly suitable, given their compact size, low mass and low power requirements. The development of diode laser-based sensors for gas detection in microgravity is presented, detailing measurements of molecular oxygen. Current progress of this work and future application possibilities for these methods on the International Space Station are discussed.

  12. A Modular Control Platform for a Diode Pumped Alkali Laser

    DTIC Science & Technology

    2008-09-01

    A Modular Control Platform for a Diode Pumped Alkali Laser Joshua Shapiro, Scott W. Teare New Mexico Institute of Mining and Technology, 801 Leroy...gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and early experiments have shown promising results. However...REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE A Modular Control Platform for a Diode Pumped Alkali Laser 5a

  13. High-power laser diodes at various wavelengths

    SciTech Connect

    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.

  14. Compact scanning-force microscope using a laser diode

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; Iams, Doug; Weissenberger, Volker; Bell, L. Stephen

    1988-12-01

    The paper describes the operation of a compact scanning-force microscope in which the gradient of force acting on a vibrating tip is monitored by a diode laser and its integrated photodiode. The system does not require reflecting or focusing elements or complicated electronics. Experimental results using this system with magnetic domains on a magnetooptic storage medium attest to the feasibility of this concept.

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

    PubMed

    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.

  16. Use of a semiconductor diode laser in laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Sakr, Ghazi; Watson, Graham M.; Lawrence, William

    1996-05-01

    The gold standard surgical treatment of benign prostatic hyperplasia (BPH) is transurethral resection of the prostate (TURP). Over the past few years, TURP has been challenged by laser prostatectomy, a technique that offered many advantages including minimal bleeding, short hospital stay, no fluid absorption, rapid learning curve and better change to preserve antegrade ejaculation. Laser prostatectomy can be done by vaporizing or coagulating prostatic tissue and more recently by using a combination of both: The hybrid technique Nd:YAG lasers have been used, (coupled with contact tips or with side firing or even bare fibers) to either coagulate or vaporize prostatic tissue. Recently semiconductor diode lasers have become available and offer certain advantages. They are compact portable units with no need for water cooling, yet they have sufficient power for tissue vaporization. Diomed (Cambridge, U.K.), produces a 60 W gallium aluminum arsenide semiconductor diode laser emitting at 810 nm. We report the first clinical experience using a semiconductor diode laser for prostates using a combination of contact tip and sidefiring.

  17. Diode Laser for Laryngeal Surgery: a Systematic Review

    PubMed Central

    Arroyo, Helena Hotz; Neri, Larissa; Fussuma, Carina Yuri; Imamura, Rui

    2016-01-01

    Introduction The diode laser has been frequently used in the management of laryngeal disorders. The portability and functional diversity of this tool make it a reasonable alternative to conventional lasers. However, whether diode laser has been applied in transoral laser microsurgery, the ideal parameters, outcomes, and adverse effects remain unclear. Objective The main objective of this systematic review is to provide a reliable evaluation of the use of diode laser in laryngeal diseases, trying to clarify its ideal parameters in the larynx, as well as its outcomes and complications. Data Synthesis We included eleven studies in the final analysis. From the included articles, we collected data on patient and lesion characteristics, treatment (diode laser's parameters used in surgery), and outcomes related to the laser surgery performed. Only two studies were prospective and there were no randomized controlled trials. Most of the evidence suggests that the diode laser can be a useful tool for treatment of different pathologies in the larynx. In this sense, the parameters must be set depending on the goal (vaporization, section, or coagulation) and the clinical problem. Conclusion: The literature lacks studies on the ideal parameters of the diode laser in laryngeal surgery. The available data indicate that diode laser is a useful tool that should be considered in laryngeal surgeries. Thus, large, well-designed studies correlated with diode compared with other lasers are needed to better estimate its effects. PMID:27096024

  18. Diode Laser for Laryngeal Surgery: a Systematic Review.

    PubMed

    Arroyo, Helena Hotz; Neri, Larissa; Fussuma, Carina Yuri; Imamura, Rui

    2016-04-01

    Introduction The diode laser has been frequently used in the management of laryngeal disorders. The portability and functional diversity of this tool make it a reasonable alternative to conventional lasers. However, whether diode laser has been applied in transoral laser microsurgery, the ideal parameters, outcomes, and adverse effects remain unclear. Objective The main objective of this systematic review is to provide a reliable evaluation of the use of diode laser in laryngeal diseases, trying to clarify its ideal parameters in the larynx, as well as its outcomes and complications. Data Synthesis We included eleven studies in the final analysis. From the included articles, we collected data on patient and lesion characteristics, treatment (diode laser's parameters used in surgery), and outcomes related to the laser surgery performed. Only two studies were prospective and there were no randomized controlled trials. Most of the evidence suggests that the diode laser can be a useful tool for treatment of different pathologies in the larynx. In this sense, the parameters must be set depending on the goal (vaporization, section, or coagulation) and the clinical problem. The literature lacks studies on the ideal parameters of the diode laser in laryngeal surgery. The available data indicate that diode laser is a useful tool that should be considered in laryngeal surgeries. Thus, large, well-designed studies correlated with diode compared with other lasers are needed to better estimate its effects.

  19. Optical Storage System for 0.4 mm Substrate Media Using 405 nm Laser Diode and Numerical Aperture 0.60/0.65 Objective Lens

    NASA Astrophysics Data System (ADS)

    Ko, Jungwan; Park, In Sik; Yoon, Du-Seop; Chung, Chong-Sam; Kim, Yoon-Gi; Ro, Myong-Do; Doh, Tae-Yong; Shin, Dong-Ho

    2001-03-01

    The most important application of the blue-laser optical storage system is the recording high-definition digital broadcasting. For this application, the next-generation blue laser optical storage system requires a data capacity of at least 2 h of a digital broadcasting data stream with a data transfer rate of 23.5 megabits per second (Mbps). In addition to the capacity goal, system compatibility with the conventional digital versatile disc (DVD) system as well as the compact disc (CD) system is important. In order to satisfy the requirements of blue-laser optical storage, a system for media with a substrates thickness of 0.4 mm was proposed, and improved molding technology, crosstalk cancellation technology, dynamic tilt compensation technology and quadrature phase shift keying (QPSK) modulated wobble addressing method were developed for the system. We confirm the feasibility of the proposed system for media with a 0.4 mm substrate using a 405 nm blue laser diode and objective lens with a numerical aperture (NA) of 0.6 (0.65 for rewritable system).

  20. Quasi-CW Laser Diode Bar Life Tests

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Krainak, Michael A.; Dallas, Joseph L.

    1997-01-01

    NASA's Goddard Space Flight Center is developing technology for satellite-based, high peak power, LIDAR transmitters requiring 3-5 years of reliable operation. Semi-conductor laser diodes provide high efficiency pumping of solid state lasers with the promise of long-lived, reliable operation. 100-watt quasi- CW laser diode bars have been baselined for the next generation laser altimeters. Multi-billion shot lifetimes are required. The authors have monitored the performance of several diodes for billions of shots and investigated operational modes for improving diode lifetime.

  1. Long-Lifetime Laser Materials For Effective Diode Pumping

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    1991-01-01

    Long quantum lifetimes reduce number of diodes required to pump. Pumping by laser diodes demonstrated with such common Nd laser materials as neodymium:yttrium aluminum garnet (Nd:YAG) and Nd:YLiF4, but such materials as Nd:LaF3, Nd:NaF.9YF3, and possibly Nd:YF3 more useful because of long lifetimes of their upper laser energy levels. Cost effectiveness primary advantage of solid-state laser materials having longer upper-laser-level lifetimes. Because cost of diodes outweighs cost of laser material by perhaps two orders of magnitude, cost reduced significantly.

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

    PubMed Central

    El Shenawy, Hanaa M.; Nasry, Sherine A.; Zaky, Ahmed A.; Quriba, Mohamed A. A.

    2015-01-01

    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 modality that provides

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

    PubMed

    El Shenawy, Hanaa M; Nasry, Sherine A; Zaky, Ahmed A; Quriba, Mohamed A A

    2015-09-15

    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. 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. 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. 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. Within the limitations of this study, the use of diode laser was shown to be a safe and effective treatment modality that provides optimal aesthetics with minimal discomfort in

  4. Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers.

    PubMed

    Demirbas, Umit; Schmalz, Michael; Sumpf, Bernd; Erbert, Götz; Petrich, Gale S; Kolodziejski, Leslie A; Fujimoto, James G; Kärtner, Franz X; Leitenstorfer, Alfred

    2011-10-10

    We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope efficiencies of 47% and 41% from continuous wave (cw) Cr:LiSAF and Cr:LiCAF lasers, respectively. In cw mode-locked operation, sub-100-fs pulse trains with average power between 200 mW and 250 mW were obtained at repetition rates around 100 MHz. Upon pumping the Cr:Colquiriite lasers with two tapered laser diodes (one from each side of the crystal), we have observed scaling of cw powers to 850 mW in Cr:LiSAF and to 650 mW in Cr:LiCAF. From the double side pumped Cr:LiCAF laser, we have also obtained ~220 fs long pulses with 5.4 nJ of pulse energy at 77 MHz repetition rate. These are the highest energy levels reported from Cr:Colquiriite so far at these repetition rates. Our findings indicate that tapered diodes in the red spectral region are likely to become the standard pump source for Cr:Colquiriite lasers in the near future. Moreover, the simplified pumping scheme might facilitate efficient commercialization of Cr:Colquiriite systems, bearing the potential to significantly boost applications of cw and femtosecond lasers in this spectral region (750-1000 nm).

  5. Realization of high performance random laser diodes

    NASA Astrophysics Data System (ADS)

    Yu, S. F.

    2011-03-01

    For the past four decades, extensive studies have been concentrated on the understanding of the physics of random lasing phenomena in scattering media with optical gain. Although lasing modes can be excited from the mirrorless scattering media, the characteristics of high scattering loss, multiple-direction emission, as well as multiple-mode oscillation prohibited them to be used as practical laser cavities. Furthermore, due to the difficulty of achieving high optical gain under electrical excitation, electrical excitation of random lasing action was seldom reported. Hence, mirrorless random cavities have never been used to realize lasers for practical applications -- CD, DVD, pico-projector, etc. Nowadays, studies of random lasing are still limited to the scientific research. Recently, the difficulty of achieving `battery driven' random laser diodes has been overcome by using nano-structured ZnO as the random medium and the careful design of heterojunctions. This lead to the first demonstration of room-temperature electrically pumped random lasing action under continuity wave and pulsed operation. In this presentation, we proposed to realize an array of quasi-one dimensional ZnO random laser diodes. We can show that if the laser array can be manipulated in a way such that every individual random laser can be coupled laterally to and locked with a particular phase relationship to its adjacent neighbor, the laser array can obtain coherent addition of random modes. Hence, output power can be multiplied and one lasing mode will only be supported due to the repulsion characteristics of random modes. This work was supported by HK PolyU grant no. 1-ZV6X.

  6. 400 mW external cavity diode laser with narrowband emission at 445 nm.

    PubMed

    Ruhnke, N; Müller, A; Eppich, B; Maiwald, M; Sumpf, B; Erbert, G; Tränkle, G

    2014-07-01

    A high-power external cavity diode laser (ECDL) system with narrowband emission is presented. The system is based on a commercially available high-power GaN laser diode. For the ECDL, a maximum optical output power of 400 mW in continuous-wave operation with narrowband emission is achieved. Longitudinal mode selection is realized by using a surface diffraction grating in Littrow configuration. A spectral width of 20 pm at 445 nm with a side-mode suppression ratio larger than 40 dB is achieved. This concept enables diode laser systems suitable for subsequent nonlinear frequency conversion into the UV spectral range.

  7. Temperature issues with white laser diodes, calculation and approach for new packages

    NASA Astrophysics Data System (ADS)

    Lachmayer, Roland; Kloppenburg, Gerolf; Stephan, Serge

    2015-01-01

    Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class systems mainly use HID or LED light sources. As a further step laser diode based systems offer a high luminance, efficiency and allow the realization of new dynamic and adaptive light functions and styling concepts. The use of white laser diode systems in automotive applications is still limited to laboratories and prototypes even though announcements of laser based front lighting systems have been made. But the environment conditions for vehicles and other industry sectors differ from laboratory conditions. Therefor a model of the system's thermal behavior is set up. The power loss of a laser diode is transported as thermal flux from the junction layer to the diode's case and on to the environment. Therefor its optical power is limited by the maximum junction temperature (for blue diodes typically 125 - 150 °C), the environment temperature and the diode's packaging with its thermal resistances. In a car's headlamp the environment temperature can reach up to 80 °C. While the difference between allowed case temperature and environment temperature is getting small or negative the relevant heat flux also becomes small or negative. In early stages of LED development similar challenges had to be solved. Adapting LED packages to the conditions in a vehicle environment lead to today's efficient and bright headlights. In this paper the need to transfer these results to laser diodes is shown by calculating the diodes lifetimes based on the presented model.

  8. 980nm diode laser pump modules operating at high temperature

    NASA Astrophysics Data System (ADS)

    Campbell, Jenna; Semenic, Tadej; Leisher, Paul; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

    2016-03-01

    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. This problem is being addressed by the team formed by Freedom Photonics and Teledyne Scientific through the development of novel high power laser chip array architectures that can operate with high efficiency when cooled with coolants at temperatures higher than 50 degrees Celsius and also the development of an advanced thermal management system for efficient heat extraction from the laser chip array. This paper will present experimental results for the optical, electrical and thermal characteristics of 980 nm diode laser pump modules operating effectively with liquid coolant at temperatures above 50 degrees Celsius, showing a very small change in performance as the operating temperature increases from 20 to 50 degrees Celsius. These pump modules can achieve output power of many Watts per array lasing element with an operating Wall-Plug-Efficiency (WPE) of >55% at elevated coolant temperatures. The paper will also discuss the technical approach that has enabled this high level of pump module performance and opportunities for further improvement.

  9. Laser thermokeratoplasty by means of a continuously emitting laser diode in the mid IR

    NASA Astrophysics Data System (ADS)

    Brinkmann, Ralf; Koop, Norbert; Kamm, Katharina; Geerling, Gerd; Kampmeier, Juergen; Birngruber, Reginald

    1996-12-01

    Laser thermokeratoplasty (LTK) has been performed with a continuously emitting, tunable laser diode at 1.86 micrometers . A study on enucleated porcine eyes was conducted in order to demonstrate the feasibility of this laser source for LTK and to determine the useful irradiation modalities. Refractive changes achieved with different application systems and a standard coagulation pattern, consisting of 8 coagulation spots on a 6 mm ring, were measured. The most promising sets of parameters were carried out in a first animal study with mini pigs. Initial refractive changes up to 6 D could be achieved in vitro and in vivo with laser powers between 120 mW and 200 mW and irradiation times of several seconds. In conclusion, the mid-IR laser diode operated at a wavelength of 1.86 micrometers seems to be the optimal source for a clinical LTK system.

  10. Beam propagation analysis of a multi-laser diode FSO system through free space

    NASA Astrophysics Data System (ADS)

    Kashani, F. D.; Hedayati Rad, M. Reza; Firozzadeh, Z.; Mahzoun, M. Reza

    2011-10-01

    In this paper beam propagation analysis of a multi-beam multi-collimator optical communication system through free space is studied. For this purpose, the propagation properties of Gaussian multi-beams through a multi-optical path including collimators in transmitters are studied and an analytical formula for intensity distribution is derived. The effects of beam divergence and beam separation distances on the propagation properties of Gaussian multi-beams are studied in detail by calculating the beam width and power in bucket (PIB). The analyses are illustrated by numerical examples.

  11. Mode-locked solid state lasers using diode laser excitation

    DOEpatents

    Holtom, Gary R [Boston, MA

    2012-03-06

    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. An asymmetric cavity provides relatively large beam spot sizes in gain medium to permit efficient coupling to a volume pumped by a laser diode bar. The cavity can include a collimation region with a controlled beam spot size for insertion of a saturable absorber and dispersion components. Beam spot size is selected to provide stable mode locking based on Kerr lensing. Pulse durations of less than 100 fs can be achieved in Yb:KGW.

  12. Using a Diode Laser for Laser-Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Tran, Yang; Whitten, J. E.

    2001-08-01

    The construction and use of a laser fluorimeter from a 635-nm red diode laser and an amplified photodiode detector are described. The low cost and monochromatic nature of diode lasers make them attractive as excitation sources for educational fluorescence experiments. Use of this type of fluorimeter is demonstrated by measuring fluorescence signals for various concentrations of Nile blue A dissolved in methanol; concentrations as low as 1 ppb are easily detected. The use of this instrument for monitoring the decomposition of a dye by an oxidizing agent is demonstrated by measuring the decay of fluorescence as a function of time for a 1 ppm Nile blue A solution after the addition of sodium hypochlorite.

  13. Impact of hydrogen peroxide activated by lighting-emitting diode/laser system on enamel color and microhardness: An in situ design

    PubMed Central

    Loiola, Ana Bárbara Araújo; Souza-Gabriel, Aline Evangelista; Scatolin, Renata Siqueira; Corona, Silmara Aparecida Milori

    2016-01-01

    Background: Hydrogen peroxide (HP) at lower concentration can provide less alteration on enamel surface and when combined with laser therapy, could decrease tooth sensitivity. This in situ study evaluated the influence of 15% and 35% HP gel activated by lighting-emitting diode (LED)/laser light for in-office tooth bleaching. Materials and Methods: Forty-four bovine enamel slabs were polished and subjected to surface microhardness (load of 25 g for 5 s). The specimens were placed in intraoral palatal devices of 11 volunteers (n = 11). Sample was randomly distributed into four groups according to the bleaching protocol: 15% HP, 15% HP activated by LED/laser, 35% HP, and 35% HP activated by LED/laser. The experimental phase comprised 15 days and bleaching protocols were performed on the 2nd and 9th days. Surface microhardness (KHN) and color changes were measured and data were analyzed by ANOVA (α = 0.05). Results: There were no significant differences in microhardness values neither in color alteration of enamel treated with 15% HP and 35% HP activated or not by LED/laser system (P > 0.05). Conclusions: Both concentrations of HP (15 or 35%), regardless of activated by an LED/laser light, did not affect the surface microhardness and had the same effectiveness in enamel bleaching. PMID:27630493

  14. Efficiency of Nd laser materials with laser diode pumping

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Cross, Patricia L.; Skolaut, Milton W., Jr.; Storm, Mark E.

    1990-01-01

    For pulsed laser-diode-pumped lasers, where efficiency is the most important issue, the choice of the Nd laser material makes a significant difference. The absorption efficiency, storage efficiency, and extraction efficiency for Nd:YAG, Nd:YLF, Nd:GSGG, Nd:BEL, Nd:YVO4, and Nd:glass are calculated. The materials are then compared under the assumption of equal quantum efficiency and damage threshold. Nd:YLF is found to be the best candidate for the application discussed here.

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

    DOEpatents

    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.

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

    PubMed

    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.

  17. Compact high brightness diode laser emitting 500W from a 100μm fiber

    NASA Astrophysics Data System (ADS)

    Heinemann, Stefan; Fritsche, Haro; Kruschke, Bastian; Schmidt, Torsten; Gries, Wolfgang

    2013-02-01

    High power, high brightness diode lasers are beginning to compete with 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 have the lowest cost of ownership, highest efficiency and most compact design among all lasers. Multiple Single Emitter (MSE) modules allow highest power and highest brightness diode lasers based on standard broad area diodes. Multiple single emitters, each rated at 12 W, are stacked in the fast axis with a monolithic slow axis collimator (SAC) array. Volume Bragg Gratings (VBG) stabilizes the wavelength and narrow the linewidth to less than 1 nm. Dichroic mirrors are used for dense wavelength multiplexing of 4 channels within 12 nm. Subsequently polarization multiplexing generates 450 W with a beam quality of 4.5 mm*mrad. Fast control electronics and miniaturized switched power supplies enable pulse rise times of less than 10 μs, with pulse widths continuously adjustable from 20 μs to cw. Further power scaling up to multi-kilowatts can be achieved by multiplexing up to 16 channels. The power and brightness of these systems enables the use of direct diode lasers for cutting and welding. The technologies can be transferred to other wavelengths to include 793 nm and 1530 nm. Optimized spectral combining enables further improvements in spectral brightness and power.

  18. Qualification of Laser Diode Arrays for Mercury Laser Altimeter Mission

    NASA Technical Reports Server (NTRS)

    Stephen, Mark; Vasilyev, Aleksey; Schafer, John; Allan, Graham R.

    2004-01-01

    NASA's requirements for high reliability, high performance satellite laser instruments have driven the investigation of many critical components; specifically, 808 nm laser diode array (LDA) pump devices. The MESSENGER mission is flying the Mercury Laser Altimeter (MLA) which is a diode-pumped Nd:YAG laser instrument designed to map the topography of Mercury. The environment imposed on the instrument by the orbital dynamics places special requirements on the laser diode arrays. In order to limit the radiative heating of the satellite from the surface of Mercury, the satellite is designed to have a highly elliptical orbit. The satellite will heat near perigee and cool near apogee. The laser power is cycled during these orbits so that the laser is on for only 30 minutes (perigee) in a 12 hour orbit. The laser heats 10 C while powered up and cools while powered down. In order to simulate these operational conditions, we designed a test to measure the LDA performance while being temperature and power cycled. Though the mission requirements are specific to NASA and performance requirements are derived from unique operating conditions, the results are general and widely applicable. We present results on the performance of twelve LDAs operating for several hundred million pulses. The arrays are 100 watt, quasi-CW, conductively-cooled, 808 nm devices. Prior to testing, we fully characterize each device to establish a baseline for individual array performance and status. Details of this characterization can be found in reference. Arrays are divided into four groups and subjected to the temperature and power cycling matrix are shown.

  19. Use of laser diodes in cavity ring-down spectroscopy

    SciTech Connect

    Zare, R.N.; Paldus, B.A.; Ma, Y.; Xie, J.

    1997-12-31

    We have demonstrated that cavity ring-down spectroscopy (CRDS), a highly sensitive absorption technique, is versatile enough to serve as a complete diagnostic for materials process control. In particular, we have used CRDS in the ultraviolet to determine the concentration profile of methyl radicals in a hot-filament diamond reactor; we have applied CRDS in the mid-infrared to detect 50 ppb of methane in a N{sub 2} environment; and, we have extended CRDS so that we can use continuous-wave diode laser sources. Using a laser diode at 810 nm, we were able to achieve a sensitivity of 2 x 10{sup -8} cm{sup -1}. Thus, CRDS can be used not only as an in situ diagnostic for investigating the chemistry of diamond film deposition, but it can also be used as a gas purity diagnostic for any chemical vapor deposition system.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  1. Method and system for powering and cooling semiconductor lasers

    DOEpatents

    Telford, Steven J; Ladran, Anthony S

    2014-02-25

    A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

  2. Ultra-narrow band diode lasers with arbitrary pulse shape modulation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ryasnyanskiy, Aleksandr I.; Smirnov, Vadim; Mokhun, Oleksiy; Glebov, Alexei L.; Glebov, Leon B.

    2017-03-01

    Wideband emission spectra of laser diode bars (several nanometers) can be largely narrowed by the usage of thick volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass. Such narrowband systems, with GHz-wide emission spectra, found broad applications for Diode Pumped Alkali vapor Lasers, optically pumped rare gas metastable lasers, Spin Exchange Optical Pumping, atom cooling, etc. Although the majority of current applications of narrow line diode lasers require CW operation, there are a variety of fields where operation in a different pulse mode regime is necessary. Commercial electric pulse generators can provide arbitrary current pulse profiles (sinusoidal, rectangular, triangular and their combinations). The pulse duration and repetition rate however, have an influence on the laser diode temperature, and therefore, the emitting wavelength. Thus, a detailed analysis is needed to understand the correspondence between the optical pulse profiles from a diode laser and the current pulse profiles; how the pulse profile and duty cycle affects the laser performance (e.g. the wavelength stability, signal to noise ratio, power stability etc.). We present the results of detailed studies of the narrowband laser diode performance operating in different temporal regimes with arbitrary pulse profiles. The developed narrowband (16 pm) tunable laser systems at 795 nm are capable of operating in different pulse regimes while keeping the linewidth, wavelength, and signal-to-noise ratio (>20 dB) similar to the corresponding CW modules.

  3. Efficient bone cutting with the novel diode pumped Er:YAG laser system: in vitro investigation and optimization of the treatment parameters

    NASA Astrophysics Data System (ADS)

    Stock, Karl; Diebolder, Rolf; Hausladen, Florian; Hibst, Raimund

    2014-03-01

    It is well known that flashlamp pumped Er:YAG lasers allow efficient bone ablation due to strong absorption at 3μm by water. Preliminary experiments revealed also a newly developed diode pumped Er:YAG laser system (Pantec Engineering AG) to be an efficient tool for use for bone surgery. The aim of the present in vitro study is the investigation of a new power increased version of the laser system with higher pulse energy and optimization of the treatment set-up to get high cutting quality, efficiency, and ablation depth. Optical simulations were performed to achieve various focus diameters and homogeneous beam profile. An appropriate experimental set-up with two different focusing units, a computer controlled linear stage with sample holder, and a shutter unit was realized. By this we are able to move the sample (slices of pig bone) with a defined velocity during the irradiation. Cutting was performed under appropriate water spray by moving the sample back and forth. After each path the ablation depth was measured and the focal plane was tracked to the actual bottom of the groove. Finally, the cuts were analyzed by light microcopy regarding the ablation quality and geometry, and thermal effects. In summary, the results show that with carefully adapted irradiation parameters narrow and deep cuts (ablation depth > 6mm, aspect ratio approx. 20) are possible without carbonization. In conclusion, these in vitro investigations demonstrate that high efficient bone cutting is possible with the diode pumped Er:YAG laser system using appropriate treatment set-up and parameters.

  4. Tunable Diode Laser Heterodyne Spectrophotometry of Ozone

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; McElroy, C. T.; Goldman, A.; Murcray, D. G.

    1988-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (less than 0.0005/ cm) solar spectra in the 9.6 micron ozone band. Observations have shown that a signal-to-noise ratio of 95 : 1 (35% of theoretical) for an integration time of 1/8 second can be achieved at a resolution of 0.0005 wavenumbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that. measured at the nearby National Oceanographic and Atmospheric Administration (NOAA) ozone monitoring facility in Boulder, Colorado.

  5. Recent advances in antiguided diode laser arrays

    NASA Astrophysics Data System (ADS)

    Mawst, L. J.; Botez, D.; Jansen, M.; Roth, T. J.; Zmudzinski, C.; Tu, C.; Yun, J.

    1992-06-01

    The paper discusses features of advanced antiguided diode laser arrays optimized for single-spatial-mode operation to high output power. Twenty-element antiguided arrays have been fabricated to operate reproducibly to CW power levels of 0.5 W with 48-50 percent efficiency. These devices were also shown to exhibit thousands of hours of reliable operation. The paper gives special attention to modeling and optimization of multiclad antiguided arrays and presents experimental results on multiclad antiguided arrays fabricated by either of the two techniques, the conventional self-aligned stripe and the complementary self-aligned stripe.

  6. Rubidium dimer destruction by a diode laser

    SciTech Connect

    Ban, T.; Aumiler, D.; Pichler, G.

    2005-02-01

    We observed rubidium dimer destruction by excitation of rubidium vapor with diode laser light tuned across the Rb D{sub 2} resonance line in a 2400 GHz tuning interval. The destruction was measured for rubidium atom concentrations in the (1-9)x10{sup 16} cm{sup -3} range, pump beam power up to 43 mW, and with a 5 Torr of the helium buffer gas. We discuss the physical mechanisms involved and specify the molecular pathways which may effectively lead to the observed dimer destruction.

  7. Broadband External-Cavity Diode Laser

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.

    2005-01-01

    A broadband external-cavity diode laser (ECDL) has been invented for use in spectroscopic surveys preparatory to optical detection of gases. Heretofore, commercially available ECDLs have been designed, in conjunction with sophisticated tuning assemblies, for narrow- band (and, typically, single-frequency) operation, as needed for high sensitivity and high spectral resolution in some gas-detection applications. However, for preparatory spectroscopic surveys, high sensitivity and narrow-band operation are not needed; in such cases, the present broadband ECDL offers a simpler, less-expensive, more-compact alternative to a commercial narrowband ECDL.

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

    SciTech Connect

    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.

  9. Effect of thermal processes on critical operation conditions of high-power laser diodes

    SciTech Connect

    Parashchuk, V V; Vu Doan Mien

    2013-10-31

    Using numerical and analytical techniques in a threedimensional approximation, we have modelled the effect of spatial thermoelastic stress nonuniformity in a laser diode – heat sink system on the output characteristics of the device in different operation modes. We have studied the influence of the pulse duration, the geometry of the laser system and its thermophysical parameters on the critical pump current density, in particular for state-of-the-art heat conductive substrate materials. The proposed approach has been used to optimise the laser diode assembly process in terms of the quality of laser crystal positioning (bonding) on a heat sink. (lasers)

  10. Transient transfection of mammalian cells using a violet diode laser

    NASA Astrophysics Data System (ADS)

    Torres-Mapa, Maria Leilani; Angus, Liselotte; Ploschner, Martin; Dholakia, Kishan; Gunn-Moore, Frank J.

    2010-07-01

    We demonstrate the first use of the violet diode laser for transient mammalian cell transfection. In contrast to previous studies, which showed the generation of stable cell lines over a few weeks, we develop a methodology to transiently transfect cells with an efficiency of up to ~40%. Chinese hamster ovary (CHO-K1) and human embryonic kidney (HEK293) cells are exposed to a tightly focused 405-nm laser in the presence of plasmid DNA encoding for a mitochondrial targeted red fluorescent protein. We report transfection efficiencies as a function of laser power and exposure time for our system. We also show, for the first time, that a continuous wave laser source can be successfully applied to selective gene silencing experiments using small interfering RNA. This work is a major step towards an inexpensive and portable phototransfection system.

  11. High-temperature diode laser pumps for directed energy fiber lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kanskar, Manoj; Bao, Ling; Chen, Zhigang; DeVito, Mark; Dong, Weimin; Grimshaw, Mike P.; Guan, Xinguo; Hemenway, David M.; Martinsen, Robert; Zhang, Jim; Zhang, Shiguo

    2017-05-01

    Kilowatt-class fiber lasers and amplifiers are becoming increasingly important building blocks for power-scaling laser systems in various different architectures for directed energy applications. Currently, state-of-the-art Yb-doped fiber lasers operating near 1060 nm operate with optical-to-optical power-conversion efficiency of about 66%. State-of-the-art fiber-coupled pump diodes near 975 nm operate with about 50% electrical-to-fiber-coupled optical power conversion efficiency at 25C heatsink temperature. Therefore, the total system electrical-to-optical power conversion efficiency is about 33%. As a result, a 50-kW fiber laser will generate 75 kW of heat at the pump module and 25 kW at the fiber laser module with a total waste heat of 100 kW. It is evident that three times as much waste heat is generated at the pump module. While improving the efficiency of the diodes primarily reduces the input power requirement, increasing the operating temperature primarily reduces the size and weight for thermal management systems. We will discuss improvement in diode laser design, thermal resistance of the package as well as improvement in fiber-coupled optical-to-optical efficiency to achieve high efficiency at higher operating temperature. All of these factors have a far-reaching implication in terms of significantly improving the overall SWAP requirements thus enabling DEW-class fiber lasers on airborne and other platforms.

  12. Rubidium Spectroscopy with an External Cavity Diode Laser

    NASA Astrophysics Data System (ADS)

    Burgess, Charity; Smith, R. Seth

    2014-03-01

    A homebuilt external cavity diode laser (ECDL) was used to provide a very narrow range of laser wavelengths near 780 nm in order to study the structure of rubidium (Rb). The absorption spectrum of Rb was measured. This spectrum was subject to Doppler-broadening of the spectral lines. A technique known as Saturated Absorption Spectroscopy was employed to eliminate the effects of Doppler-broadening and to obtain a high resolution spectrum for Rubidium. The setup, operation, and performance of this system will be described. Research made possible by a REAL grant from Francis Marion University.

  13. Multimode-diode-pumped gas (alkali-vapor) laser

    SciTech Connect

    Page, R H; Beach, R J; Kanz, V K

    2005-08-22

    We report the first demonstration of a multimode-diode-pumped gas laser--Rb vapor operating on the 795 nm resonance transition. Peak output of {approx}1 Watt was obtained using a volume-Bragg-grating stabilized pump diode array. The laser's output radiance exceeded the pump radiance by a factor greater than 2000. Power scaling (by pumping with larger diode arrays) is therefore possible.

  14. Multimode-diode-pumped gas (alkali-vapor) laser.

    PubMed

    Page, Ralph H; Beach, Raymond J; Kanz, V Keith; Krupke, William F

    2006-02-01

    We report what we believe to be the first demonstration of a multimode-diode-pumped gas laser: Rb vapor operating on the 795 nm D1 resonance transition. Peak output of approximately 1 W was obtained using a volume-Bragg-grating stabilized pump diode array. The laser's output radiance exceeded the pump radiance by a factor greater than 2000. Power scaling (by pumping with larger diode arrays) is therefore possible.

  15. Efficient diffractive collimator for edge-emitting laser diodes

    NASA Astrophysics Data System (ADS)

    Kowalik, Andrzej; Góra, Krzysztof; Adamkiewicz, Grażyna; Ziętek, Monika; Mikuła, Grzegorz; Kołodziejczyk, Andrzej; Jaroszewicz, Zbigniew

    2006-04-01

    Compared with conventional optical systems, diffractive optical elements are more suitable to transform laser diode beams because they can form more complex wavefronts and better fulfill requirements of miniaturization. However, high numerical aperture needed to collimate the fast axis of edge-emitting laser diodes demands extremely high spatial frequency elements when single DOE is used. That involves complicated design methods based on rigorous diffraction theory and fabricating technology with sub-wavelength resolution and nanometer accuracy. To overcome these difficulties we propose a transmission DOE consisting of elliptical and cylindrical zone plates fabricated onto opposite sides of a substrate. The main advantage of such a solution lies in fact that each of the zone plates has smaller spatial frequency and can be made even as 8-phase-level element with theoretically 95% diffraction efficiency using available microlithographic technology. In result, monolithic collimating system that allows to compensate astigmatism and to convert an elliptical laser diode light beam to circular one can be achieved with NA higher than 0.5 and efficiency over 80%.

  16. CO.sub.2 optically pumped distributed feedback diode laser

    DOEpatents

    Rockwood, Stephen D.

    1980-01-01

    A diode laser optically pumped by a CO.sub.2 coherent source. Interference fringes generated by feeding the optical pumping beam against a second beam, periodically alter the reflectivity of the diode medium allowing frequency variation of the output signal by varying the impingent angle of the CO.sub.2 laser beams.

  17. Monitoring The Atmosphere By Diode-Laser Spectroscopy

    NASA Technical Reports Server (NTRS)

    Loewenstein, Max; Podolske, James

    1988-01-01

    Report describes state of art of tunable-diode-laser second-harmonic spectroscopy applied to measurements of concentrations of trace constituents of atmosphere. Combination of temperature, composition, and drive-current tuning, wavelengths of tunable diode lasers varied over infrared range of 3 to 30 micrometer, containing spectral lines of many molecules of interest in atmospheric research.

  18. Circular polarization emission from an external cavity diode laser

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Zhang, Fan; Lakhtakia, Akhlesh; Pursel, Sean M.; Horn, Mark W.

    2008-08-01

    We construct an external cavity diode laser (ECDL) comprising structurally left-handed chiral sculptured-thin-film (STF) mirrors for pure circular-polarized (CP) emission, and observed single mode, left-handed CP lasing performance. The extinction ratio of CP output was found to increase rapidly near the threshold of the injection-current for the laser diodes.

  19. LEDs and laser diodes in schlieren optics methods

    SciTech Connect

    Pawliszyn, J.

    1987-02-01

    The pointing noise of light beams generated by light emitting diodes (LEDs) and laser diodes are investigated and compared with the stability of the He--Ne laser and the incandescent lamp beam. LEDs have superior pointing noise characteristics compared to other light sources with their angular position drift of only about 50 nrad.

  20. Means for phase locking the outputs of a surface emitting laser diode array

    NASA Technical Reports Server (NTRS)

    Lesh, James R. (Inventor)

    1987-01-01

    An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

  1. Laser lipolysis: skin tightening in lipoplasty using a diode laser.

    PubMed

    Wolfenson, Moisés; Hochman, Bernardo; Ferreira, Lydia Massako

    2015-05-01

    New devices have been developed for surgical repair of deformities caused by localized fat deposits associated with skin laxity. The use of these devices requires the adoption of safety parameters. The aim of this study was to investigate skin tightening by laser lipolysis, using a dual-wavelength diode laser. This prospective, cross-sectional study was conducted between June of 2008 and July of 2010 with 41 consecutive patients who underwent laser lipolysis to correct contour deformities. Laser lipolysis was performed with a diode laser operating at two wavelengths (924 and 975 nm) controlled independently, and using three different tip lengths, allowing treatment of small, medium, and large areas of adipose tissue. The procedure was performed under local anesthesia in a surgical setting. To calculate the optimal cumulative energy, a total energy dose of 5 kJ/10 × 10-cm skin area was used as a safety parameter to prevent treatment complications. The circumferences of body regions were measured preoperatively, immediately after surgery, and 90 days later. Measurements were compared using the Wilcoxon test at a significance level of 0.05 (p < 0.05). A significant skin tightening was observed in all patients, regardless of the body site involved (i.e., face, breast, arms, or waist regions), and no complications occurred. Laser lipolysis results in progressive skin tightening over time. Therapeutic, IV.

  2. Comparison between sequentional treatment with diode and alexandrite lasers versus alexandrite laser alone in the treatment of hirsutism.

    PubMed

    Nilforoushzadeh, Mohammad Ali; Naieni, Farahnaz Fatemi; Siadat, Amir Hossein; Rad, Leila

    2011-11-01

    Laser systems that are commonly used for the treatment of hirsutism include the ruby laser (694 nm), the diode laser (800 nm), the alexandrite laser (755 nm) and the Nd:YAG laser (1084 nm). The diode laser and alexandrite laser are considered effective in treatment of hirsutism in dark-skinned patients. The response of hairs to these laser systems is variable and not complete. In this study, we compared the efficacy of these two laser systems for permanent hair removal. This was a randomized, controlled clinical trial that was performed with women of the age range 15-45 years old. After obtaining informed consent, the samples were randomized into two groups using random allocation software. The first group was treated with alexandrite laser alone (four sessions, two months apart). The second group was treated sequentially with diode laser for the first two sessions and alexandrite laser for the next two sessions. Overall, 111 patients (57 patients in the alexandrite laser group and 54 patients in the sequential diode-alexandrite laser group) were evaluated. There was no significant difference regarding mean of hair reduction between the two groups during the courses of treatment. Except for the first session, there was no significant difference regarding percent of patient satisfaction between the two groups (P value >0.05). Comparison between the two groups showed no significant difference one month, three months and six months after the last treatment (P value >0.05). Regarding the results of our study, there is no significant difference between sequential treatment with diode and alexandrite lasers versus alexandrite laser alone in the treatment of hirsutism. We suggest that in further studies, the efficacy of sequential treatment with other laser systems is evaluated against single treatment methods.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  5. Femtosecond diode-pumped mode-locked neodymium lasers

    NASA Astrophysics Data System (ADS)

    Kubeček, Václav; Jelínek, Michal; Čech, Miroslav; Vyhlídal, David; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Qian, Xiaobo; Wang, Jingya; Xu, Jun

    2016-12-01

    Fluoride-type crystals (CaF2, SrF2) doped with neodymium Nd3+ and codoped with buffer ions for breaking clusters of active ions and increasing fluorescence efficiency, present interesting alternative as laser active media for the diode-pumped mode-locked lasers. In comparison with widely used materials as Nd:YAG or Nd:YVO4, they have broad emission spectra as well as longer fluorescence lifetime, in comparison with Nd:glass, SrF2 and CaF2 have better thermal conductivity. In spite of the fact, that this thermal conductivity decreases with Nd3+ doping concentration, these crystals are alternative for the Nd:glass in subpicosecond mode-locked laser systems. In this paper we review the basic results reported recently on these active materials and in the second part we present our results achieved in low power diode pumped passively mode locked lasers with Nd,La:CaF2 and Nd,Y:SrF2 crystals. The pulses as short as 258 fs at wavelength of 1057 nm were obtained in the first case, while 5 ps long pulses at 1065 nm were generated from the second laser system.

  6. New diode wavelengths for pumping solid-state lasers

    SciTech Connect

    Skidmore, J.A.; Emanuel, M.A.; Beach, R.J.

    1995-01-01

    High-power laser-diode arrays have been demonstrated to be viable pump sources for solid-state lasers. The diode bars (fill factor of 0.7) were bonded to silicon microchannel heatsinks for high-average-power operation. Over 12 W of CW output power was achieved from a one cm AlGaInP tensile-strained single-quantum-well laser diode bar. At 690 nm, a compressively-strained single-quantum-well laser-diode array produced 360 W/cm{sup 2} per emitting aperture under CW operation, and 2.85 kW of pulsed power from a 3.8 cm{sup 2} emitting-aperture array. InGaAs strained single-quantum-well laser diodes emitting at 900 nm produced 2.8 kW pulsed power from a 4.4 cm{sup 2} emitting-aperture array.

  7. Design and optimization of the combination film in 10kW diode laser cladding source

    NASA Astrophysics Data System (ADS)

    Zhu, Hong-bo; Lin, Xing-chen; Hao, Ming-ming; Zhang, Jin-sheng; Ning, Yong-qiang

    2015-08-01

    According to the special requirements of combination film in 10kW diode laser cladding source, the polarization combination film at 915nm was designed and grew. Film system is designed at different film materials based on the design theory. The non-QWOT film is optimized using the needle optimization and double sided coating by Optilayer software. The film was used in the 10kW diode laser source after high temperature aging testing. The film formed by Ta2O5 is very stable under IBAD, which can meet the reliability of 10kW diode laser cladding source in industry

  8. A single-frequency, diode-pumped Nd:YLF laser at 657 nm: a frequency and intensity noise comparison with an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Nunez Portela, M.; Wetter, N. U.; Zondy, J. J.; Cruz, F. C.

    2013-02-01

    We report on a continuous wave, diode-pumped, intracavity frequency-doubled Nd:YLF (yttrium lithium fluoride) single-frequency ring laser designed for high-resolution spectroscopy of the calcium intercombination transition at 657 nm. We measured its frequency modulation (FM) and amplitude modulation (AM) noise and compared it with an extended cavity diode laser (ECDL). The Nd:YLF laser has much lower FM noise, extending to 50 kHz in comparison with 5 MHz for the ECDL, and slightly higher AM noise, transferred from the pump diode laser. This characterization is important for the design of servo-systems for frequency or intensity stabilization, and also for quantum optics experiments. A Nd:YLF laser at 657 nm can become an attractive high-power ‘local oscillator’ for a calcium optical clock, with a fundamental ‘telecom wavelength’ that can be directly used for remote transfer in optical fibers.

  9. Diode Laser Pumped Alkali Vapor Lasers with Exciplex-Assisted Absorption

    DTIC Science & Technology

    2013-05-14

    ORGANIZATION Emory University, 1515 Dickey Drive, Atlanta, GA 30322 REPORT NUMBER The College of Optics and Photonics, University of Central Florida, 4000...supplies high power pumping system to AFRL. 1S. SUBJECT TERMS High-power lasers, line-narrowed diode lasers, volume Bragg grating, gas phase, OPAL, hybrid...Central Florida, School of Optics/CREOL Michael C. Heaven Department of Chemistry Emory University Atlanta, GA 30322 Multidisciplinary Research

  10. Theoretical model for frequency locking a diode laser with a Faraday cell

    NASA Technical Reports Server (NTRS)

    Wanninger, P.; Shay, T. M.

    1992-01-01

    A new method was developed for frequency locking a diode lasers, called 'the Faraday anomalous dispersion optical transmitter (FADOT) laser locking', which is much simpler than other known locking schemes. The FADOT laser locking method uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. The FADOT method is vibration insensitive and exhibits minimal thermal expansion effects. The system has a frequency pull in the range of 443.2 GHz (9 A). The method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters.

  11. Photoluminescence excitation measurements using pressure-tuned laser diodes

    SciTech Connect

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

    2015-06-15

    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. Tunable diode lasers for 3-30 micron infrared operation

    NASA Technical Reports Server (NTRS)

    Linden, K. J.

    1983-01-01

    The tunable diode laser is now widely used in high resolution infrared spectroscopy studies, taking into account laboratory and industrial applications. The present investigation is concerned with advances related to laser performance and reliability. The advances are the result of improvements in materials and device technologies. Reliability data for broad-area Pb(1-x)Sn(x)Se lasers are considered along with performance improvements in stripe-geometry lasers, laser performance at wavelengths above 25 microns, and laser performance at wavelengths below 4 microns. Attention is given to tunable Pb-salt infrared diode lasers, mesa-stripe geometry lasers of Pb(1-x)Sn(x)Se and PbS(1-x)Se(x), and long wavelength diode laser emission observed in both Pb(1-x)Sn(x)Te and Pb(1-x)Sn(x)Se.

  13. Tunable, diode side-pumped Er:YAG laser

    DOEpatents

    Hamilton, C.E.; Furu, L.H.

    1997-04-22

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.

  14. Tunable, diode side-pumped Er: YAG laser

    DOEpatents

    Hamilton, Charles E.; Furu, Laurence H.

    1997-01-01

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 .mu.m, and is tunable over a 6 nm range near about 2.936 .mu.m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 .mu.m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 .mu.m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems.

  15. Laser diode ignition characteristics of Zirconium Potassium Perchlorate (ZPP)

    NASA Technical Reports Server (NTRS)

    Callaghan, Jerry D.; Tindol, Scot

    1993-01-01

    Hi-Shear Technology, Corp., (HSTC) has designed and built a Laser equivalent NASA Standard Initiator (LNSI). Langlie tests with a laser diode output initiating ZPP were conducted as a part of this effort. The test parameters include time to first pressure, laser power density requirements, and ignition time. The data from these laser tests on ZPP are presented.

  16. Computer-Assisted Experiments with a Laser Diode

    ERIC Educational Resources Information Center

    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…

  17. Computer-Assisted Experiments with a Laser Diode

    ERIC Educational Resources Information Center

    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…

  18. Spin polarization of {sup 87}Rb atoms with ultranarrow linewidth diode laser: Numerical simulation

    SciTech Connect

    Wang, Z. G.; Jiang, Q. Y.; Zhan, X.; Chen, Y. D.; Luo, H.

    2016-08-15

    In order to polarize {sup 87}Rb vapor effectively with ultranarrow linewidth diode laser, we studied the polarization as a function of some parameters including buffer gas pressure and laser power. Moreover, we also discussed the methods which split or modulate the diode laser frequency so as to pump the two ground hyperfine levels efficiently. We obtained some useful results through numerical simulation. If the buffer gas pressure is so high that the hyperfine structure is unresolved, the polarization is insensitive to laser frequency at peak absorption point so frequency splitting and frequency modulation methods do not show improvement. At low pressure and laser power large enough, where the hyperfine structure is clearly resolved, frequency splitting and frequency modulation methods can increase polarization effectively. For laser diodes, frequency modulation is easily realized with current modulation, so this method is attractive since it does not add any other components in the pumping laser system.

  19. Optical frequency domain reflectometry based fiber Bragg grating vibration sensor array using sinusoidal current modulation of laser diodes

    NASA Astrophysics Data System (ADS)

    Wada, Atsushi; Tanaka, Satoshi; Takahashi, Nobuaki

    2015-09-01

    We present multipoint vibration sensing using fiber Bragg gratings and optical frequency domain refrectometry (OFDR). In OFDR based method, the maximum number of arrayed sensor can be few thousands and the measurement time is determined by wavelength scanning rate of a light source. In our sensor system, a laser diode is used as a wavelength scanning light source. Lasing wavelength of a laser diode can be modulated by changing its injection current. The injection current can be precisely modulated at high frequency up to 1 MHz using a laser-diode controller and wavelength scanning can be then easily achieved with a laser diode.

  20. High power laser diodes for the NASA direct detection laser transceiver experiment

    NASA Technical Reports Server (NTRS)

    Seery, Bernard D.; Holcomb, Terry L.

    1988-01-01

    High-power semiconductor laser diodes selected for use in the NASA space laser communications experiments are discussed. The diode selection rationale is reviewed, and the laser structure is shown. The theory and design of the third mirror lasers used in the experiments are addressed.

  1. Diode-pumped 10 W continuous wave cesium laser.

    PubMed

    Zhdanov, Boris; Knize, R J

    2007-08-01

    An efficient cesium vapor laser pumped with a continuous wave laser diode array has been demonstrated. The linewidth of the pump source was narrowed using the external cavity to match it to the cesium absorption line. The output power of the continuous wave cesium laser was 10 W, which exceeds previous results by more than a factor of 10, and the slope efficiency was 68%. The overall optical efficiency was 62%, which is a factor of 6 higher than previous pulsed laser results for alkali lasers with diode laser array pumping.

  2. A compact multi-wavelength optoacoustic system based on high-power diode lasers for characterization of double-walled carbon nanotubes (DWCNTs) for biomedical applications

    NASA Astrophysics Data System (ADS)

    Leggio, Luca; de Varona, Omar; Escudero, Pedro; Carpintero del Barrio, Guillermo; Osiński, Marek; Lamela Rivera, Horacio

    2015-06-01

    During the last decade, Optoacoustic Imaging (OAI), or Optoacoustic Tomography (OAT), has evolved as a novel imaging technique based on the generation of ultrasound waves with laser light. OAI may become a valid alternative to techniques currently used for the detection of diseases at their early stages. It has been shown that OAI combines the high contrast of optical imaging techniques with high spatial resolution of ultrasound systems in deep tissues. In this way, the use of nontoxic biodegradable contrast agents that mark the presence of diseases in near-infrared (NIR) wavelengths range (0.75-1.4 um) has been considered. The presence of carcinomas and harmful microorganisms can be revealed by means of the fluorescence effect exhibited by biopolymer nanoparticles. A different approach is to use carbon nanotubes (CNTs) which are a contrast agent in NIR range due to their absorption characteristics in the range between 800 to 1200 nm. We report a multi-wavelength (870 and 905 nm) laser diode-based optoacoustic (OA) system generating ultrasound signals from a double-walled carbon nanotubes (DWCNTs) solution arranged inside a tissue-like phantom, mimicking the scattering of a biological soft tissue. Optoacoustic signals obtained with DWCNTs inclusions within a tissue-like phantom are compared with the case of ink-filled inclusions, with the aim to assess their absorption. These measurements are done at both 870 and 905 nm, by using high power laser diodes as light sources. The results show that the absorption is relatively high when the inclusion is filled with ink and appreciable with DWCNTs.

  3. Diode-pumped continuous-wave Nd:glass laser

    NASA Technical Reports Server (NTRS)

    Kozlovsky, W. J.; Fan, T. Y.; Byer, R. L.

    1986-01-01

    The paper reports on diode-laser pumping of monolithic Nd:glass laser oscillators. End pumping with a single-stripe diode laser, a threshold of 2.2 mW, and a slope efficiency of 42 percent were observed on a 2-mm-long oscillator with a mode radius of 35 microns. The oscillator generated 2.5 mW of single-ended output power in many axial modes.

  4. Comparative efficiency analysis of GaN-based light-emitting diodes and laser diodes

    NASA Astrophysics Data System (ADS)

    Piprek, Joachim

    2016-07-01

    Nobel laureate Shuji Nakamura predicted in 2014 that GaN-based laser diodes are the future of solid state lighting. However, blue GaN-lasers still exhibit less than 40% wall-plug efficiency, while some GaN-based blue light-emitting diodes exceed 80%. This paper investigates non-thermal reasons behind this difference. The inherently poor hole conductivity of the Mg-doped waveguide cladding layer of laser diodes is identified as main reason for their low electrical-to-optical energy conversion efficiency.

  5. Innovative Facet Passivation for High-Brightness Laser Diodes

    DTIC Science & Technology

    2016-02-05

    Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 high-power laser diodes, catastrophic optical damage, high energy lasers REPORT...factor bar) desired for military high energy lasers (HELs). COD of the front facet (laser mirror) is the main failure mechanism that constrains scaling... energy lasers (HELs). COD of the front facet (laser mirror) is the main failure mechanism that constrains scaling LD power by 10X over the SOA to 600 W

  6. Geometrical Transformation of Linear Diode-Laser Arrays for Longitudinal Pumping of Solid-State Lasers

    DTIC Science & Technology

    1992-05-26

    of Nd:YAG crystal vs incident power from the geometrically transformed laser - diode array. 24 12 TEM00 output power from Nd:YAG laser when pumped by n...MASSACHUSETTS INSTITUTE OF TECHNOLOGY LINCOLN LABORATORY GEOMETRICAL TRANSFORMATION OF LINEAR DIODE - LASER ARRAYS FOR LONGITUDINAL PUMPING OF SOLID-STATE...Photograph of pump spot at the lens focal plane. 22 10 Curvature of the laser - diode array emitting facet. 23 11 TEMOO output power from 1.06 pm transition

  7. High brightness diode lasers controlled by volume Bragg gratings

    NASA Astrophysics Data System (ADS)

    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.

  8. Design and fabrication of a resonant mirrors for locking blue laser diodes

    NASA Astrophysics Data System (ADS)

    Byrd, Matthew; Baghdady, Joshua; Pung, Aaron J.; Johnson, Eric; Lee, Kyu; Magnusson, Robert; Binun, Paul; McCormick, Kyle

    2015-03-01

    The recent development and refinement of Gallium nitride (GaN) semiconductor devices has produced both blue light emitting diodes (LEDs) and laser diodes, which provide an efficient means to obtain high emission powers in the blue spectral range. Such sources have potential applications in both imaging and communication systems. However, many applications require precise control over the spectral emission from these devices and the current blue laser diodes lack this ability. In this paper, we demonstrate a method to control the spectral emission from GaN blue laser diodes. We present the simulation and subsequent fabrication of a guided-mode resonance filter (GMRF) that can be used to lock the output wavelength of a GaN blue laser diode. Successful locking of the emission wavelength with respect to fluctuations in the surrounding environment addresses challenges associated with communication systems. Our experiment uses an optical cavity with a GaN blue laser diode source and an on-axis narrowband GMRF fabricated for 445.2 nm. Based on spectral drift of the diode emission caused by an increase in input current, experimental measurements were taken with the GMRF installed to verify wavelength locking capability.

  9. Selective laser suture lysis with a compact, low-cost, red diode laser.

    PubMed

    Shein, Petr; Cilip, Christopher M; Quinto, Guilherme; Behrens, Ashley; Fried, Nathaniel M

    2008-01-01

    The argon (blue-green) laser is currently used for vaporization of sutures during ophthalmic surgery. However, previous studies have reported more effective laser suture lysis and a lower rate of complications using the krypton (red) laser. Red wavelengths are selectively absorbed by the nylon sutures, but are minimally absorbed by adjacent tissue, and not absorbed by hemoglobin, unlike the argon laser wavelengths. More compact and less expensive red diode lasers have recently become commercially available for surgical applications. This study explores the use of a compact, lowpower, red diode laser for selective laser suture lysis. A 225 mW, 660-nm diode laser was used to vaporize 10-0 nylon sutures in human cornea samples with a single laser pulse, pulse energy of 150 mJ, pulse duration of 100 ms, and spot diameter of 55 mum. The red diode laser may represent an inexpensive, compact, and safer alternative laser for use in laser suture lysis during ophthalmic surgery.

  10. Room-Temperature Spin Polariton Diode Laser

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Aniruddha; Baten, Md Zunaid; Iorsh, Ivan; Frost, Thomas; Kavokin, Alexey; Bhattacharya, Pallab

    2017-08-01

    A spin-polarized laser offers inherent control of the output circular polarization. We have investigated the output polarization characteristics of a bulk GaN-based microcavity polariton diode laser at room temperature with electrical injection of spin-polarized electrons via a FeCo /MgO spin injector. Polariton laser operation with a spin-polarized current is characterized by a threshold of ˜69 A / cm2 in the light-current characteristics, a significant reduction of the electroluminescence linewidth and blueshift of the emission peak. A degree of output circular polarization of ˜25 % is recorded under remanent magnetization. A second threshold, due to conventional photon lasing, is observed at an injection of ˜7.2 kA /cm2 . The variation of output circular and linear polarization with spin-polarized injection current has been analyzed with the carrier and exciton rate equations and the Gross-Pitaevskii equations for the condensate and there is good agreement between measured and calculated data.

  11. Active stabilization of a diode laser injection lock.

    PubMed

    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.

  12. Active stabilization of a diode laser injection lock

    NASA Astrophysics Data System (ADS)

    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.

  13. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  14. Microlens frames for laser diode arrays

    DOEpatents

    Skidmore, J.A.; Freitas, B.L.

    1999-07-13

    Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter. 12 figs.

  15. Microlens frames for laser diode arrays

    DOEpatents

    Skidmore, Jay A.; Freitas, Barry L.

    1999-01-01

    Monolithic microlens frames enable the fabrication of monolithic laser diode arrays and are manufactured inexpensively with high registration, and with inherent focal length compensation for any lens diameter variation. A monolithic substrate is used to fabricate a low-cost microlens array. The substrate is wet-etched or sawed with a series of v-grooves. The v-grooves can be created by wet-etching, by exploiting the large etch-rate selectivity of different crystal planes. The v-grooves provide a support frame for either cylindrical or custom-shaped microlenses. Because the microlens frames are formed by photolithographic semiconductor batch-processing techniques, they can be formed inexpensively over large areas with precise lateral and vertical registration. The v-groove has an important advantage for preserving the correct focus for lenses of varying diameter.

  16. Linewidth-tunable laser diode array for rubidium laser pumping

    SciTech Connect

    Li Zhiyong; Tan Rongqing; Xu Cheng; Li Lin

    2013-02-28

    To optimise the pump source for a high-power diodepumped rubidium vapour laser, we have designed a laser diode array (LDA) with a narrowed and tunable linewidth and an external cavity formed by two volume Bragg gratings (VBGs). Through controlling the temperature differences between the two VBGs, the LDA linewidth, which was 1.8 nm before mounting the two VBGs, was tunable from 100 pm to 0.2 nm, while the output power changed by no more than 4 %. By changing simultaneously the temperature in both VBGs, the centre wavelength in air of the linewidth-tunable LDA was tunable from 779.40 nm to 780.05 nm. (control of laser radiation parameters)

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

    NASA Astrophysics Data System (ADS)

    Le, T.; Müller, A.; Sumpf, B.; Jensen, O. B.; Hansen, A. K.; Andersen, P. E.

    2016-03-01

    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-laser. In this work we present an alternative method by deploying frequency-doubled IR diodes with good beam qualities to pump fs-lasers. The revolutionary approach allows choosing any pump wavelengths in the green region and avoids complicated relay optics for the diodes. For the first time we show results of a diode-pumped 10 fs-laser and how a single diode setup can be integrated into a 30 x 30 cm2 fs-laser system generating sub 20 fs laser pulses with output power towards half a Watt. This technology paves the way for a new class of very compact and cost-efficient fs-lasers for life science and industrial applications.

  18. Deep ultraviolet light-emitting and laser diodes

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Asif, Fatima; Muhtadi, Sakib

    2016-02-01

    Nearly all the air-water purification/polymer curing systems and bio-medical instruments require 250-300 nm wavelength ultraviolet light for which mercury lamps are primarily used. As a potential replacement for these hazardous mercury lamps, several global research teams are developing AlGaN based Deep Ultraviolet (DUV) light emitting diodes (LEDs) and DUV LED Lamps and Laser Diodes over Sapphire and AlN substrates. In this paper, we review the current research focus and the latest device results. In addition to the current results we also discuss a new quasipseudomorphic device design approach. This approach which is much easier to integrate in a commercial production setting was successfully used to demonstrate UVC devices on Sapphire substrates with performance levels equal to or better than the conventional relaxed device designs.

  19. Tunable external cavity laser employing uncooled superluminescent diode.

    PubMed

    Oh, Su Hwan; Kim, Ki Soo; Ju, Jung Jin; Kim, Min-Su; Yoon, Ki-Hong; Oh, Dae Kon; Noh, Young-Ouk; Lee, Hyung-Jong

    2009-06-08

    We have fabricated a tunable external cavity laser (T-ECL) based on a superluminescent diode and a polymeric waveguide Bragg reflector, providing a cost-effective solution for wavelength division multiplexing-passive optical network (WDM-PON) systems. The wavelength of the T-ECL is tuned through 100 GHz-spacing 16 channels by the thermo-optic tuning of the refractive index of the polymer waveguide at a low input power of 70 mW. The maximum output power and the slope efficiency of the uncooled diode at 20 (75) degrees C are 8.83 (3.80) mW and 0.107 (0.061) W/A, respectively. The T-ECL operated successfully in the direct modulation for 1.25 Gbit/s transmissions over 20 km.

  20. 100 kW peak power picosecond thulium-doped fiber amplifier system seeded by a gain-switched diode laser at 2 μm.

    PubMed

    Heidt, A M; Li, Z; Sahu, J; Shardlow, P C; Becker, M; Rothhardt, M; Ibsen, M; Phelan, R; Kelly, B; Alam, S U; Richardson, D J

    2013-05-15

    We report on the generation of picosecond pulses at 2 μm directly from a gain-switched discrete-mode diode laser and their amplification in a multistage thulium-doped fiber amplifier chain. The system is capable of operating at repetition rates in the range of 2 MHz-1.5 GHz without change of configuration, delivering high-quality 33 ps pulses with up to 3.5 μJ energy and 100 kW peak power, as well as up to 18 W of average power. These results represent a major technological advance and a 1 order of magnitude increase in peak power and pulse energy compared to existing picosecond sources at 2 μm.

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

    NASA Technical Reports Server (NTRS)

    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. Narrow-line external cavity diode laser micro-packaging in the NIR and MIR spectral range

    NASA Astrophysics Data System (ADS)

    Jiménez, A.; Milde, T.; Staacke, N.; Aßmann, C.; Carpintero, G.; Sacher, J.

    2017-07-01

    Narrow-linewidth tunable diode lasers are an important tool for spectroscopic instrumentation. Conventional external cavity diode lasers offer high output power and narrow linewidth. However, most external cavity diode lasers are designed as laboratory instrument and do not allow portability. In comparison, other commonly used lasers, like distributed feedback lasers (DFB) that are capable of driving a handheld device, are limited in power and show linewidths which are not sufficiently narrow for certain applications. We present new miniaturized types of tunable external cavity diode laser which overcome the drawbacks of conventional external cavity diode lasers and which preserve the advantages of this laser concept. Three different configurations are discussed in this article. The three types of miniaturized external cavity diode laser systems achieve power values of more than 50 mW within the 1.4 μm water vapor absorption band with excellent side-mode suppression and linewidth below 100 kHz. Typical features outstand with respect to other type of laser systems which are of extended use such as DFB laser diodes. The higher output power and the lower linewidth will enable a higher sensitivity and resolution for a wide range of applications.

  3. Beam shaping design for coupling high power diode laser stack to fiber.

    PubMed

    Ghasemi, Seyed Hamed; Hantehzadeh, Mohammad-Reza; Sabbaghzadeh, Jamshid; Dorranian, Davoud; Lafooti, Majid; Vatani, Vahid; Rezaei-Nasirabad, Reza; Hemmati, Atefeh; Amidian, Ali Asghar; Alavian, Seyed Ali

    2011-06-20

    A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible.

  4. Laser-diode-pumped solid-state laser driver at ILE Osaka

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masanobu; Naito, Kenta; Nakatsuka, Masahiro; Nakai, Sadao

    1992-11-01

    Using a conceptual designing technique developed we evaluate the feasibility of laser diode pumped solid state laser systems which have 1OMJ blue output 10 overall efficiency and 10Hz repetition rate with typical solid state laser materials for the reactor driver from both technical and economical points of view. For an economical laser fusion reactor driver the solid state laser materials are required to have the following properties hw/a 40J/cm2 (hco : the laser photon energy a : the stimulated emission cross section) a thermal shock parameter of <=3W/cm a nonlinear index of refraction smaller than --3x1013 esu and a fluorescence lifetime of <=4ms. 1.

  5. Application of COTS high-speed 980-nm pump laser diode and driver for free-space laser communication terminal

    NASA Astrophysics Data System (ADS)

    Chan, Eric Y.; Adams, Jeff C.; Saint Clair, Jonathan M.; Morrison, Kenneth A.; Sosa, Martin

    1999-06-01

    In our Photonics West 98 paper, we presented our study results on using commercially available 860 nm high power laser diodes and high-speed laser driver for free-space laser communication terminal application. We demonstrated the feasibility of a free space laser communication link using a junction-up 860 nm high power laser diode driven by a high current laser driver from Hytek Microsystems up to 622 Mb/s. Recent development in high speed InGaAs/GaAs strained layer quantum well (SLQW) laser at 980 nm has provided an additional design option for a laser communication terminal. The advantages of using the 980 nm laser are: (1) WDM market in the telecom industry has created a volume demand for the 980 nm pump lasers. The future cost of 980 nm lasers is expected to be lower due to the economy of scale. (2) In our previous publications, we have demonstrated CW operation of strained layer QW laser at temperature higher than 200 degree(s)C. There is a potential for this type of laser diode to operate in a much harsher and higher temperature environment, and (3) 980 nm pump laser has output power comparable to high power 860 nm laser diodes. In this paper, we will present the high data rate characteristics of a high-speed 980 nm (SLQW) pump laser. Using commercial-off-the-shelf laser drivers we will demonstrate the laser transmitter system characteristics from 622 Mb/s to 3 Gb/s. Detail experimental results on bit- error-rate measurement for a 980 nm device will be presented.

  6. Advances in AlGaInN laser diode technology for defence, security and sensing applications

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    Laser diodes fabricated from the AlGaInN material system is an emerging technology 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., 380nm, to the visible 530nm, by tuning the indium content of the laser GaInN quantum well, giving rise to new and novel applications including displays and imaging systems, free-space and underwater telecommunications and the latest quantum technologies such as optical atomic clocks and atom interferometry.

  7. High-power 2-μm diode-pumped Tm:YAG laser

    NASA Astrophysics Data System (ADS)

    Beach, Raymond J.; Sutton, Steven B.; Honea, Eric C.; Skidmore, Jay A.; Emanuel, Mark A.

    1996-03-01

    Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory we have demonstrated a compact Tm:YAG laser capable of generating greater than 50 W of cw 2 micrometer laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, are discussed. The 2 micrometer radiation produced by the 3F4 - 3H6 transition of Tm3+ has many practical applications because it is strongly absorbed by water and also because it is an 'eye-safe' wavelength. The strong absorption of 2 micrometer radiation by water makes this transition a very attractive candidate for performing laser surgical procedures as most tissue types are predominately composed of liquid water. The fact that 2 micrometer radiation is considered 'eye-safe' makes this transition attractive for laser range finding and remote sensing applications where other laser wavelengths could pose a safety hazard. At sufficiently high doping densities, Tm3+ exhibits a beneficial two-for-one quantum pump efficiency enabling well developed AlGaAs laser diode arrays to be used as efficient excitation sources. Many applications requiring 2 micrometer laser radiation such as remote sensing, laser radar, anti sensor, sensor spoofing, and OPO pumping have driven the development of diode pumped all solid state TM3+ laser systems because of their potential for efficiency, compactness, and ruggedness. Here we focus on Tm3+:YAG and the scalable diode end-pumping technology developed at LLNL which enables higher average power operation of diode pumped Tm3+ laser systems than has previously been possible. To date we have demonstrated cw operation of this laser to power levels of 51 W. The end-pumping technology used is the same as was previously used to demonstrate a 100 mJ Q-switched Nd:YLF laser. (Truncated.)

  8. Diode laser absorption spectroscopy of lithium isotopes

    NASA Astrophysics Data System (ADS)

    Olivares, Ignacio E.; González, Iván A.

    2016-10-01

    We study Doppler-limited laser intensity absorption, in a thermal lithium vapor containing 7Li and 6Li atoms in a 9 to 1 ratio, using a narrow-linewidth single-longitudinal-mode tunable external cavity diode laser at the wavelength of 670.8 nm. The lithium vapor was embedded in helium or argon buffer gas. The spectral lineshapes were rigorously predicted for D_1 and D_2 for the lithium 6 and 7 isotope lines using reduced optical Bloch equations, specifically derived, from a density matrix analysis. Here, a detailed comparison is provided of the predicted lineshapes with the measured 7Li-D_2, 7Li-D_1, 6Li-D_2 and 6Li-D_1 lines, in the case of high vapor density and with intensity above the saturation intensity. To our knowledge, this is the first time that such detailed comparison is reported in the open literature. The calculations were also extended to saturated absorption spectra and compared to measured Doppler-free 7Li-D_2 and 6Li-D_2 hyperfine lines.

  9. Stable diode lasers for hydrogen precision spectroscopy

    NASA Astrophysics Data System (ADS)

    Alnis, J.; Matveev, A.; Kolachevsky, N.; Wilken, T.; Holzwarth, R.; Hänsch, T. W.

    2008-10-01

    We report on an external cavity diode laser at 972 nmstabilized to a mid-plane mounted Fabry-Perot (FP) resonator with afinesse of 400000. The 0.5 Hz optical beat note line width betweentwo similar lasers (Allan deviation 2 × 10-15) is limitedby thermal noise properties of two independent FP resonators. Thelong term drift of the FP resonator and mirror substrates made fromUltra-Low-Expansion glass (ULE) is small and can be well predictedon time intervals up to many hours if the resonator is stabilized atthe zero thermal expansion temperature Tc. Using a Peltierelement in a vacuum chamber for temperature stabilization allowsstabilization of the FP cavity to Tc which is usually below theroom temperature. Beat note measurements with a femtosecond opticalfrequency comb referenced to a H-maser during 15 hours have shown awell defined linear drift of the FP resonance frequency of about 60 mHz/s with residual frequency excursions of less than ±20 Hz.

  10. Fault protection of broad-area laser diodes

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    Detailed reliability studies of high-power, CW, broad-area, GaAs-based laser- diodes were performed. Optical and electrical transients occurring prior to device failure by catastrophic optical-damage (COD) were observed. These transients were correlated with COD formation as observed in laser diodes with an optical window in the n-side electrode. In addition, custom electronics were designed to fault-protect the laser diodes during aging tests, i.e. each time a transient (fault) was detected, the operating current was temporarily cut off within 4μs of fault detection. The lifetime of fault-protected 808-nm laser-diode bars operated at a constant current of 120A (~130W) and 35°C exceeded similar unprotected devices by factors of 2.

  11. Active stabilization of a diode laser injection lock

    SciTech Connect

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

    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.

  12. Early fire sensing using near-IR diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Bomse, David S.; Hovde, D. Christian; Chen, Shin-Juh; Silver, Joel A.

    2002-09-01

    We describe research leading to a trace gas detection system based on optical absorption using near-IR diode lasers that is intended to provide early warning of incipient fires. Applications include "high loss" structures such as office buildings, hospitals, hotels and shopping malls as well as airplanes and manned spacecraft where convention smoke detectors generate unacceptably high false alarm rates. Simultaneous or near-simultaneous detection of several gases (typically carbon dioxide, carbon monoxide, acetylene and hydrogen cyanide) provides high sensitivity while reducing the chance of false alarms. Continuous measurement of carbon dioxide concentrations also provides an internal check of instrument performance because ambient levels will not drop below ~350 ppm.

  13. Homogenization of high power diode laser beams for pumping and direct applications

    NASA Astrophysics Data System (ADS)

    Traub, Martin; Hoffmann, Hans-Dieter; Plum, Heinz-Dieter; Wieching, Kristin; Loosen, Peter; Poprawe, Reinhart

    2006-02-01

    High power diode lasers have become an established source for numerous direct applications like metal hardening and polymer welding due to their high efficiency, small size, low cost and high reliability. These laser sources are also used for efficient pumping of solid state lasers as Nd:YAG lasers. To increase the output power of diode lasers up to several kilowatts, the emitters are scaled laterally by forming a diode laser bar and vertically by forming a diode laser stack. For most applications like hardening and illumination, though, the undefined far field distribution of most commercially available high power diode laser stacks states a major drawback of these devices. As single emitters and bars can fail during their lifetime, the near field distribution does not remain constant. To overcome these problems, the intensity distribution can be homogenized by a waveguide or by microoptic devices. The waveguide segments the far field distribution by several total internal reflections, and these segments are overlaid at the waveguide's exit surface. By the microoptic device, the near field is divided into beamlets which are overlaid by a field lens. Both approaches are presented, and realized systems are described.

  14. [New approach to photoepilation. Diode laser with SHR (Super Hair Removal) compared to alexandrite laser].

    PubMed

    Hammes, S; Ockenfels, H M; Metelmann, H-R; Raulin, C; Karsai, S

    2010-10-01

    Photoepilation has been an essential field of application of dermatologic laser therapy for many years. The present article evaluates whether the use of a new operation mode of a long-pulsed diode laser can be effective, nearly painless, with few side effects and independent of the skin type. To this aim, its use has been compared to an established method of photoepilation. In a controlled prospective study with 18 (♀=12, ♂=6) patients aged between 22 and 58 years, the effects of photoepilation with the long-pulsed alexandrite laser and the long-pulsed diode laser, operated in the Super Hair Removal mode (SHR), were compared. The alexandrite laser is slightly more effective with fair skin types; the SHR mode is clearly more effective with dark skin types. Regarding painfulness, the SHR mode is clearly superior. In terms of speed, the two systems are comparable. The alexandrite laser is more user-friendly because of its light and small handpiece. The major advantages of the SHR mode are its effectiveness in dark skin types and its lack of pain. The alexandrite laser is slightly more effective with fair skin types, slightly faster and its handling is considerably more comfortable. None of the two systems has yet brought about a breakthrough with fair hair.

  15. Diffraction Limited 3.15 Microns Cascade Diode Lasers

    DTIC Science & Technology

    2014-06-01

    carriers recycling by the cascade pumping . The narrow ridge 6- m-wide waveguides were defined by inductively coupled plasma (ICP) reactive ion etching...diffraction limited, diode lasers, cascade pumping REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S...of GaSb-based type-I QW diode lasers by utilizing cascade pumping scheme4. The carriers were recycled with 100% efficiency between two gain stages

  16. Athermal diode-pumped laser designator modules for targeting application

    NASA Astrophysics Data System (ADS)

    Crepy, B.; Closse, G.; Da Cruz, J.; Sabourdy, D.; Montagne, J.; Nguyen, L.

    2012-10-01

    We report on the development and characteristics of athermal diode-pumped designator modules as Original Equipment Manufacturer (OEM) for targeting application. These modules are designed with the latest diode-pumped technology minimizing volume and power consumption. The core technology allows to address multi-platforms requirements such as land or airborne. Products are composed of a Laser Transmitter Unit (LTU) and Laser Electronic Unit (LEU) for modular approach.

  17. Sb-Based Mid-Infrared Diode Lasers

    DTIC Science & Technology

    2002-01-01

    low as 121 A/cm2 reflecting the superior quality of our diode lasers, all values recorded at 280 K. A high characteristic temperature To of 179 K for...K temperature interval. Room temperature cw output powers exceeding 1.7 W have been demonstrated for broad area single element devices with high ...operating temperatures while maintaining high power efficiency. For the 2-3 pin wavelength interval, the conventional interband diode laser approach is

  18. Efficient potassium diode pumped alkali laser operating in pulsed mode.

    PubMed

    Zhdanov, Boris V; Rotondaro, Matthew D; Shaffer, Michael K; Knize, Randall J

    2014-07-14

    This paper presents the results of our experiments on the development of an efficient hydrocarbon free diode pumped alkali laser based on potassium vapor buffered by He gas at 600 Torr. A slope efficiency of more than 50% was demonstrated with a total optical conversion efficiency of 30%. This result was achieved by using a narrowband diode laser stack as the pump source. The stack was operated in pulsed mode to avoid limiting thermal effects and ionization.

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

    PubMed

    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.

  20. Beam shaping for kilowatt fiber-coupled diode lasers by using one-step beam cutting-rotating of prisms.

    PubMed

    Wu, Yulong; Dong, Zhiyong; Chen, Yongqi; Qi, Yaoyao; Yuan, Xiandan; Qi, Yunfei; Xu, Li; Lin, Xuechun; Zou, Yonggang; Zhao, Pengfei

    2016-12-01

    The beam quality mismatch of laser diode stacks in both axes limits many direct applications for fiber or solid laser pumping and material processing. In this paper, a one-step cutting-rotating beam shaping system has been designed to homogenize the beam quality of two polarization-multiplexing laser diode stacks. Coupling laser diode stacks consisting of eight bars into a standard fiber with a core diameter of 600 μm and an NA of 0.22 is achieved. The simulative result shows that the system will have an output power over 1056 W. By using the technique, the production of compact and high brightness fiber-coupling diode lasers can be directly used for laser cladding and laser surface hardening processes.

  1. Optical monitoring of high power direct diode laser cladding

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Farahmand, Parisa; Kovacevic, Radovan

    2014-12-01

    Laser cladding is one of the most advanced surface modification techniques which can be used to build and repair high-value components. High power direct diode laser (HPDDL) offers unique quality and cost advantages over other lasers (CO2, Nd:YAG). Especially its rectangular laser beam with top-hat intensity distribution makes HPDDL an ideal tool for large area cladding. In order to utilize this technique successfully, the development of on-line monitoring and process control is necessary. In this study, an optical monitoring system consisting of a high-speed CCD camera, a pyrometer, and an infrared camera was used to analyze the mass- and heat-transfer in the cladding process. The particle transport in flight was viewed by a high-speed CCD camera; the interaction between powder flow and laser beam was observed by an infrared camera; and the thermal behavior of the molten pool was recorded by the pyrometer and the infrared camera. The effects of the processing parameters on the laser attenuation, particle heating and clad properties were investigated based on the obtained signals. The optical monitoring method improved the understanding about mutual interrelated phenomena in the cladding process.

  2. [Measurement of oxygen concentration using multimode diode laser absorption spectroscopy].

    PubMed

    Gao, Guang-zhen; Cai, Ting-dong; Hu, Bo; Jia, Tian-jun

    2015-01-01

    Tunable diode laser absorption spectroscopy (TDLAS) is a widely used technique for high sensitivity, good selectivity and fast response. It is widely used in environment monitoring, industrial process control and biomedical sensing. In order to overcome the drawbacks of TDLAS including high cost, poor stability and center wavelength shift problem. A multi-mode diode laser system based on correlation spectroscopy and wavelength modulation spectroscopy (TMDL-COSPEC-WMS) was used to measure O2 concentration near 760nm at the 1%~30% range of near room temperature. During the experiment, the light is splitter into two beams, respectively through the sample and measuring cell, two receiving optical signal collection containing gas concentration information sent back stage treatment, invert the oxygen concentration through correlation and ratio between measured signal and reference signal, the correlation spectroscopy harmonic detection technique is used to improve the stability of the system and the signal to noise ratio. The result showed that, there was a good linear relationship between the measured oxygen concentration and the actual concentration value. A detection limit of 280 pmm. m in the 1 atmospheric which approved of the same sample. A continuous measurement for oxygen with the standard deviation of 0. 056% in ambient air during approximately 30 minutes confirms the stability and the capability of the system. The design of the system includes soft and hardware can meet the needs of oxygen online monitoring. The experimental device is simple and easy to use, easy to complex environment application.

  3. Study of pseudo noise CW diode laser for ranging applications

    NASA Technical Reports Server (NTRS)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-01-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  4. A near-infrared acetylene detection system based on a 1.534 μm tunable diode laser and a miniature gas chamber

    NASA Astrophysics Data System (ADS)

    He, Qixin; Zheng, Chuantao; Liu, Huifang; Li, Bin; Wang, Yiding; Tittel, Frank K.

    2016-03-01

    A near-infrared (NIR) dual-channel differential acetylene (C2H2) detection system was experimentally demonstrated based on tunable diode laser absorption spectroscopy (TDLAS) technique and wavelength modulation spectroscopy (WMS) technique. A distributed feedback (DFB) laser modulated by a self-developed driver around 1.534 μm is used as light source. A miniature gas chamber with 15 cm path length is adopted as absorption pool, and an orthogonal lock-in amplifier is developed to extract the second harmonic (2f) signal. Sufficient standard C2H2 samples with different concentrations were prepared, and detailed measurements were carried out to study the detection performance. A good linear relationship is observed between the amplitude of the 2f signal and C2H2 concentration within the range of 200-10,000 ppm, and the relative measurement error is less than 5% within the whole range. A long-term monitoring lasting for 20 h on a 1000 ppm C2H2 sample was carried out, and the maximum concentration fluctuation is less than 2%. Due to the capability of using long-distance and low-loss optical fiber, the gas-cell can be placed in the filed for remote monitoring, which enables the system to have good prospects in industrial field.

  5. Diode-pumped Alexandrite ring laser for lidar applications

    NASA Astrophysics Data System (ADS)

    Munk, A.; Jungbluth, B.; Strotkamp, M.; Hoffmann, H.-D.; Poprawe, R.; Höffner, J.

    2016-03-01

    We present design and performance data of a diode-pumped Q-switched Alexandrite ring laser in the millijoule regime, which is longitudinally pumped by laser diode bar modules in the red spectral range. As a first step, a linear resonator was designed and characterized in qcw operation as well as in Q-switched operation. Based on these investigations, two separate linear cavities were set up, each with one Alexandrite crystal longitudinally pumped by one diode module. The two cavities are fused together and form a ring cavity which yields up to 6 mJ pulse burst energy in the qcw regime at 770 nm.

  6. Direct diode-pumped Kerr Lens 13 fs Ti:sapphire ultrafast oscillator using a single blue laser diode

    DOE PAGES

    Backus, Sterling; Colorado State Univ., Fort Collins, CO; Kirchner, Matt; ...

    2017-05-18

    We demonstrate a direct diode-pumped Kerr Lens Modelocked Ti:sapphire laser producing 13 fs pulses with 1.85 nJ energy at 78 MHz (145 mW) using a single laser diode pump. We also present a similar laser using three spectrally combined diodes, generating >300 mW output power with >50 nm bandwidth. We discuss the use of far-from TEM00 pump laser sources, and their effect on the Kerr lens modelocking process.

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

    PubMed

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

    2016-09-15

    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.

  8. Direct diode lasers and their advantages for materials processing and other applications

    NASA Astrophysics Data System (ADS)

    Fritsche, Haro; Ferrario, Fabio; Koch, Ralf; Kruschke, Bastian; Pahl, Ulrich; Pflueger, Silke; Grohe, Andreas; Gries, Wolfgang; Eibl, Florian; Kohl, Stefanie; Dobler, Michael

    2015-03-01

    The brightness of diode lasers is improving continuously and has recently started to approach the level of some solid state lasers. The main technology drivers over the last decade were improvements of the diode laser output power and divergence, enhanced optical stacking techniques and system design, and most recently dense spectral combining. Power densities at the work piece exceed 1 MW/cm2 with commercially available industrial focus optics. These power densities are sufficient for cutting and welding as well as ablation. Single emitter based diode laser systems further offer the advantage of fast current modulation due their lower drive current compared to diode bars. Direct diode lasers may not be able to compete with other technologies as fiber or CO2-lasers in terms of maximum power or beam quality. But diode lasers offer a range of features that are not possible to implement in a classical laser. We present an overview of those features that will make the direct diode laser a very valuable addition in the near future, especially for the materials processing market. As the brightness of diode lasers is constantly improving, BPP of less than 5mm*mrad have been reported with multikW output power. Especially single emitter-based diode lasers further offer the advantage of very fast current modulation due to their low drive current and therefore low drive voltage. State of the art diode drivers are already demonstrated with pulse durations of <10μs and repetition rates can be adjusted continuously from several kHz up to cw mode while addressing power levels from 0-100%. By combining trigger signals with analog modulations nearly any kind of pulse form can be realized. Diode lasers also offer a wide, adaptable range of wavelengths, and wavelength stabilization. We report a line width of less than 0.1nm while the wavelength stability is in the range of MHz which is comparable to solid state lasers. In terms of applications, especially our (broad) wavelength

  9. Multiple Isotope Magneto Optical Trap from a single diode laser

    NASA Astrophysics Data System (ADS)

    Gomez, Eduardo; Valenzuela, Victor; Hamzeloui, Saeed; Gutierrez, Monica

    2013-05-01

    We present a simple design for a Dual Isotope Magneto Optical Trap. The system requires a single diode laser, a fiber modulator and a tapered amplifier to trap and completely control both 85Rb and 87Rb. We generate all the frequencies needed for trapping both species using the fiber intensity modulator. All the frequencies are amplified simultaneously with the tapered amplifier. The position and power of each frequency is now controlled independently on the RF rather than on the optical side. This introduces an enormous simplification for laser cooling that often requires an acousto-optic modulator for each frequency. The range of frequency changes is much bigger than what is available with acousto-optic modulators since in our case is determined by the modulator bandwidth (10 GHz). Additional isotopes can be simply added by including additional RF frequencies to the modulator and extra beams for other uses can be produced the same way. Support from CONACYT, PROMEP and UASLP.

  10. High performance diode lasers emitting at 780-820 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; DeVito, M.; Grimshaw, M.; Leisher, P.; Zhou, H.; Dong, W.; Guan, X.; Zhang, S.; Martinsen, R.; Haden, J.

    2012-03-01

    High power 780-820 nm diode lasers have been developed for pumping and material processing systems. This paper presents recent progress in the development of such devices for use in high performance industrial applications. A newly released laser design in this wavelength range demonstrates thermally limited >25W CW power without catastrophic optical mirror damage (COMD), with peak wallplug efficiency ~65%. Ongoing accelerated lifetesting projects a time to 5% failure of ~10 years at 5 and 8 W operating powers for 95 and 200 μm emitter widths, respectively. Preliminary results indicate the presence and competition of a random and wear-out failure mode. Fiber-coupled modules based on arrays of these devices support >100W reliable operation, with a high 56% peak efficiency (ex-fiber) and improved brightness/reliability.

  11. Optical Feedback Stabilization of Laser Diodes for Passive Resonance Ring Laser Gyro Applications.

    DTIC Science & Technology

    1985-12-01

    rugged optical rotation sensors are not far off. The main purpose of this research was to a construct narrow spectral linewidth semiconductor laser . In... Linewidth and Sensitivity Pssive Resonant Ring Laser Gyroscopes............. Frequency Noise and Laser Linewidth ............. 8.......... * Laser Diode... Linewidth Reduction by Optical F ee dbk........................... ck . . .. . . . 12 Semiconductor Laser Mode Behavior with Optical Feedback

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  14. Diode-Pumped Solid-State Lasers for Internal Fusion Energy

    SciTech Connect

    Payne, S A; Bibeau, C; Beach, R J; Bayramian, A; Chanteloup, J C; Ebbers, C A; Emanuel, M A; Orth, C D; Rothenberg, J. E; Schaffers, K I; Skidmore, J A; Sutton, S B; Zapata, L E; Powell, H T

    1999-11-15

    We have begun building the ''Mercury'' laser system as the first in a series of new generation diode-pumped solid-state lasers for inertial fusion research. Mercury will integrate three key technologies: diodes, crystals, and gas cooling, within a unique laser architecture that is scalable to kilojoule and megajoule energy levels for fusion energy applications. The primary near-term performance goals include 10% electrical efficiencies at 10 Hz and 100J with a 2-10 ns pulse length at 1.047 mm wavelength. When completed, Mercury will allow rep-rated target experiments with multiple chambers for high energy density physics research.

  15. Portable multiwavelength laser diode source for handheld photoacoustic devices

    NASA Astrophysics Data System (ADS)

    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.

  16. High-power diode lasers for optical communications applications

    NASA Technical Reports Server (NTRS)

    Carlin, D. B.; Goldstein, B.; Channin, D. J.

    1985-01-01

    High-power, single-mode, double-heterojunction AlGaAs diode lasers are being developed to meet source requirements for both fiber optic local area network and free space communications systems. An individual device, based on the channeled-substrate-planar (CSP) structure, has yielded single spatial and longitudinal mode outputs of up to 90 mW CW, and has maintained a single spatial mode to 150 mW CW. Phase-locked arrays of closely spaced index-guided lasers have been designed and fabricated with the aim of multiplying the outputs of the individual devices to even higher power levels in a stable, single-lobe, anastigmatic beam. The optical modes of the lasers in such arrays can couple together in such a way that they appear to be emanating from a single source, and can therefore be efficiently coupled into optical communications systems. This paper will review the state of high-power laser technology and discuss the communication system implications of these devices.

  17. High-power diode lasers for optical communications applications

    NASA Technical Reports Server (NTRS)

    Carlin, D. B.; Goldstein, B.; Channin, D. J.

    1985-01-01

    High-power, single-mode, double-heterojunction AlGaAs diode lasers are being developed to meet source requirements for both fiber optic local area network and free space communications systems. An individual device, based on the channeled-substrate-planar (CSP) structure, has yielded single spatial and longitudinal mode outputs of up to 90 mW CW, and has maintained a single spatial mode to 150 mW CW. Phase-locked arrays of closely spaced index-guided lasers have been designed and fabricated with the aim of multiplying the outputs of the individual devices to even higher power levels in a stable, single-lobe, anastigmatic beam. The optical modes of the lasers in such arrays can couple together in such a way that they appear to be emanating from a single source, and can therefore be efficiently coupled into optical communications systems. This paper will review the state of high-power laser technology and discuss the communication system implications of these devices.

  18. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H{sub 2}O mole fraction

    SciTech Connect

    Xu, Lijun Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

    2016-01-15

    To monitor two-dimensional (2D) distributions of temperature and H{sub 2}O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors’ knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H{sub 2}O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm{sup −1} (1343.3 nm) and 7185.6 cm{sup −1} (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H{sub 2}O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H{sub 2}O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

  19. Diode-Pumped, Q-Switched, Frequency-Doubling Laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

    Experimental Q-switched, diode-pumped, intracavity-frequency-doubling laser generates pulses of radiation at wavelength of 532 nm from excitation at 810 nm. Principal innovative feature distinguishing laser from others of its type: pulsed operation of laser at pulse-repetition frequencies higher than reported previously. Folded resonator keeps most of second-harmonic radiation away from Q-switcher, laser crystal, and laser diodes. Folding mirror highly reflective at fundamental laser wavelength and highly transmissive at second-harmonic laser wavelength. By virtue of difference of about 0.6 percent between reflectivities in two polarizations at fundamental wavelength, folding mirror favors polarized oscillation at fundamental wavelength. This characteristic desirable for doubling of frequency in some intracavity crystals.

  20. Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

    PubMed

    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.

  1. Highly efficient fiber coupling of laser diode bars with > 50% electro-optical efficiency out of the fiber core

    NASA Astrophysics Data System (ADS)

    Fornahl, Udo; Revermann, Markus; Meinschien, Jens

    2008-02-01

    Fiber-coupled diode lasers have become an established source for many industrial applications due to their high wall-plug efficiency, minimal maintenance and cost per watt. To decrease system size and cost for cooler and driver, high coupling efficiencies have become more and more important. Recent developments in broad area laser diode bars (BALB) and beam shaping systems with micro-optical components are leading to new highly efficient fiber coupling. We present newly developed high power diode laser modules which are performing at outstanding efficiencies with smallest package design. The combination of recently designed laser diode bars on passive heat sinks and optimized micro-optics results in laser modules with up to 60W out of a 200μm fiber with a 0.22 NA and > 50% electro-optical efficiency out of the fiber core, based on only one laser diode bar. The applications for such laser diode modules range from pumping of fiber lasers and amplifiers, over materials processing to medical applications. The presentation of the technology will show a path to scale high-brightness laser systems to higher power levels and efficiencies. The combination of different coupling techniques will allow laser modules with 100W out of 100μm fiber core up to 1.6kW out of 400μm fiber core with electro-optical efficiencies of > 45%.

  2. Respiratory complications after diode-laser-assisted tonsillotomy.

    PubMed

    Fischer, Miloš; Horn, Iris-Susanne; Quante, Mirja; Merkenschlager, Andreas; Schnoor, Jörg; Kaisers, Udo X; Dietz, Andreas; Kluba, Karsten

    2014-08-01

    Children with certain risk factors, such as comorbidities or severe obstructive sleep apnea syndrome (OSAS) are known to require extended postoperative monitoring after adenotonsillectomy. However, there are no recommendations available for diode-laser-assisted tonsillotomy. A retrospective chart review of 96 children who underwent diode-laser-assisted tonsillotomy (07/2011-06/2013) was performed. Data for general and sleep apnea history, power of the applied diode-laser (λ = 940 nm), anesthesia parameters, the presence of postoperative respiratory complications and postoperative healing were evaluated. After initially uncomplicated diode-laser-assisted tonsillotomy, an adjustment of post-anesthesia care was necessary in 16 of 96 patients due to respiratory failure. Respiratory complications were more frequent in younger children (3.1 vs. 4.0 years, p = 0.049, 95 % CI -1.7952 to -0.0048) and in children who suffered from nocturnal apneas (OR = 5.00, p < 0.01, 95 % CI 1.4780-16.9152) or who suffered from relevant comorbidities (OR = 4.84, p < 0.01, 95 % CI 1.5202-15.4091). Moreover, a diode-laser power higher than 13 W could be identified as a risk factor for the occurrence of a postoperative oropharyngeal edema (OR = 3.45, p < 0.01, 95 % CI 1.3924-8.5602). Postoperative respiratory complications should not be underestimated in children with sleep-disordered breathing (SDB). Therefore, children with SDB, children with comorbidities or children younger than 3 years should be considered "at risk" and children with confirmed moderate to severe OSAS should be referred to a PICU following diode-laser-assisted tonsillotomy. We recommend a reduced diode-laser power (<13 W) to reduce oropharyngeal edema.

  3. Catastrophic Optical Damage in High-Power, Broad-Area Laser Diodes

    NASA Astrophysics Data System (ADS)

    Chin, Aland K.; Bertaska, Rick K.

    Catastrophic optical damage (COD) is semiconductor material within the optical cavity of laser diodes that is thermally damaged by the laser light. COD results in the failure of laser diodes. The phenomena of COD in high-power, broad-area laser diodes are described along with methods to eliminate it.

  4. Broad-Area Laser Diode With Fiber-Optic Injection

    NASA Technical Reports Server (NTRS)

    Hazel, Geoffrey; Mead, Patricia; Davis, Christopher; Cornwell, Donald

    1992-01-01

    Fiber-optic injection-locked broad-area laser diode features single-mode output via fiber-optic injection and serves as compact, rugged, high-power near-infrared source. Useful in free-space and fiber-optic communication links, as communication-receiver preamplifier, and pump source for solid-state lasers.

  5. A tunable diode laser emitting orthogonally polarised radiation modes

    SciTech Connect

    Fadyushin, A B; Velichansky, Vladimir L; Senkov, N V; Lukin, M D; Scully, M O; Fleischauer, M

    2002-07-31

    A new scheme of the external cavity of a diode laser is described. The scheme provides emission of two closely spaced ({Delta}{lambda} < 10{sup -3} nm) orthogonally polarised modes, which can be tuned within the gain line, with the mode interval continuously changed. (lasers)

  6. Effects of the space environment on laser diodes

    NASA Astrophysics Data System (ADS)

    Roux, M.

    Laser diodes have been irradiated to investigate their behavior in the space environment. The InGaAsP/InP laser diodes used are manufactured by a technology projected to have high-output-power potential. The principal parameters of the devices, which included InP p-n junctions and double-heterostructure lasers with broad and narrow stripe-geometries, measured during 1 MeV electron irradiation, did not degrade appreciably. The partial annealing of irradiation-induced defects that takes place reduces the ultimate degradation induced by radiation.

  7. Computer Processing Of Tunable-Diode-Laser Spectra

    NASA Technical Reports Server (NTRS)

    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.

  8. Novel diode laser-based sensors for gas sensing applications

    NASA Technical Reports Server (NTRS)

    Tittel, F. K.; Lancaster, D. G.; Richter, D.

    2000-01-01

    The development of compact spectroscopic gas sensors and their applications to environmental sensing will be described. These sensors employ mid-infrared difference-frequency generation (DFG) in periodically poled lithium niobate (PPLN) crystals pumped by two single-frequency solid state lasers such as diode lasers, diode-pumped solid state, and fiber lasers. Ultrasensitive, highly selective, and real-time measurements of several important atmospheric trace gases, including carbon monoxide, nitrous oxide, carbon dioxide, formaldehyde [correction of formaldehye], and methane, have been demonstrated.

  9. Frequency narrowing of a 25 W broad area diode laser

    NASA Astrophysics Data System (ADS)

    Sell, J. F.; Miller, W.; Wright, D.; Zhdanov, B. V.; Knize, R. J.

    2009-02-01

    We report on the spectral narrowing of a high powered (25 W) broad area diode laser using an external cavity with a holographic diffraction grating. In a Littman-Metcalf configuration, the external cavity is able to reduce the linewidth of the diode laser to primarily a single longitudinal mode (1.8 MHz) for output powers of ≤10 W at 852 nm. Many physics applications could benefit from such high powered, narrow linewidth lasers; however both the frequency stability and the spatial profile of the output beam show room for improvement.

  10. Temperature Gradients In Diode-pumped Alkali Lasers

    DTIC Science & Technology

    2012-01-18

    radiation from bars or stacks of diode lasers is absorbed by atomic potassium, rubidium , or cesium. Collision-induced energy transfer populates the upper...laser level, and lasing is achieved in the near-IR on the D1 (pump) line. A rubidium laser pumped by a 1.28kW diode stack with a 0.35nm spectral band...negligible, offering the potential for low waste heat loads. However, cycling of atoms by the pump beam can be >109photons/ atom -s. The energy of the spin

  11. Diode-pumped solid state laser for inertial fusion energy

    SciTech Connect

    Payne, S.A.; Krupke, W.F.; Orth, C.D.

    1994-11-01

    The authors evaluate the prospect for development of a diode-pumped solid-state-laser driver in an inertial fusion energy power plant. Using a computer code, they predict that their 1 GWe design will offer electricity at 8.6 cents/kW {center_dot} hr with the laser operating at 8.6% efficiency and the recycled power level at 31%. The results of their initial subscale experimental testbed of a diode-pumped solid state laser are encouraging, demonstrating good efficiencies and robustness.

  12. Novel diode laser-based sensors for gas sensing applications

    NASA Technical Reports Server (NTRS)

    Tittel, F. K.; Lancaster, D. G.; Richter, D.

    2000-01-01

    The development of compact spectroscopic gas sensors and their applications to environmental sensing will be described. These sensors employ mid-infrared difference-frequency generation (DFG) in periodically poled lithium niobate (PPLN) crystals pumped by two single-frequency solid state lasers such as diode lasers, diode-pumped solid state, and fiber lasers. Ultrasensitive, highly selective, and real-time measurements of several important atmospheric trace gases, including carbon monoxide, nitrous oxide, carbon dioxide, formaldehyde [correction of formaldehye], and methane, have been demonstrated.

  13. Photoporation and cell transfection using a violet diode laser

    NASA Astrophysics Data System (ADS)

    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.

  14. Thermally widely tunable laser diodes with distributed feedback

    SciTech Connect

    Todt, R.; Jacke, T.; Meyer, R.; Amann, M.-C.

    2005-07-11

    A thermally widely tunable buried heterostructure laser diode with distributed feedback (DFB) is demonstrated. This device requires only two tuning currents for wide quasicontinuous wavelength tuning, thereby facilitating easy and fast device calibration and control. Furthermore, being based on regular DFB laser fabrication technology, it is readily manufacturable. By using window structures instead of cleaved facets plus antireflection coatings, a regular tuning behavior has been achieved for a DFB-like widely tunable laser diode with only two tuning currents. The laser diode covers the wavelength range between 1552 and 1602 nm. Requiring side-mode suppression ratio and output power above 30 dB and 10 mW, respectively, a wavelength range of 43 nm is accessible.

  15. Thermally widely tunable laser diodes with distributed feedback

    NASA Astrophysics Data System (ADS)

    Todt, R.; Jacke, T.; Meyer, R.; Amann, M.-C.

    2005-07-01

    A thermally widely tunable buried heterostructure laser diode with distributed feedback (DFB) is demonstrated. This device requires only two tuning currents for wide quasicontinuous wavelength tuning, thereby facilitating easy and fast device calibration and control. Furthermore, being based on regular DFB laser fabrication technology, it is readily manufacturable. By using window structures instead of cleaved facets plus antireflection coatings, a regular tuning behavior has been achieved for a DFB-like widely tunable laser diode with only two tuning currents. The laser diode covers the wavelength range between 1552 and 1602 nm. Requiring side-mode suppression ratio and output power above 30 dB and 10 mW, respectively, a wavelength range of 43 nm is accessible.

  16. Feasibility of supersonic diode pumped alkali lasers: Model calculations

    SciTech Connect

    Barmashenko, B. D.; Rosenwaks, S.

    2013-04-08

    The feasibility of supersonic operation of diode pumped alkali lasers (DPALs) is studied for Cs and K atoms applying model calculations, based on a semi-analytical model previously used for studying static and subsonic flow DPALs. The operation of supersonic lasers is compared with that measured and modeled in subsonic lasers. The maximum power of supersonic Cs and K lasers is found to be higher than that of subsonic lasers with the same resonator and alkali density at the laser inlet by 25% and 70%, respectively. These results indicate that for scaling-up the power of DPALs, supersonic expansion should be considered.

  17. High average power diode pumped solid state laser

    NASA Astrophysics Data System (ADS)

    Gao, Yue; Wang, Yanjie; Chan, Amy; Dawson, Murray; Greene, Ben

    2017-03-01

    A new generation of high average power pulsed multi-joule solid state laser system has been developed at EOS Space Systems for various space related tracking applications. It is a completely diode pumped, fully automated multi-stage system consisting of a pulsed single longitudinal mode oscillator, three stages of pre-amplifiers, two stages of power amplifiers, completely sealed phase conjugate mirror or stimulated Brillouin scattering (SBS) cell and imaging relay optics with spatial filters in vacuum cells. It is capable of generating pulse energy up to 4.7 J, a beam quality M 2 ~ 3, pulse width between 10–20 ns, and a pulse repetition rate between 100–200 Hz. The system has been in service for more than two years with excellent performance and reliability.

  18. Narrow linewidth operation of a spectral beam combined diode laser bar.

    PubMed

    Zhu, Zhanda; Jiang, Menghua; Cheng, Siqi; Hui, Yongling; Lei, Hong; Li, Qiang

    2016-04-20

    Our experiment is expected to provide an approach for realizing ultranarrow linewidth for a spectral beam combined diode laser bar. The beams of a diode laser bar are combined in a fast axis after a beam transformation system. With the help of relay optics and a transform lens with a long focal length of 1.5 m, the whole wavelength of a spectral combined laser bar can be narrowed down to 0.48 nm from more than 10 nm. We have achieved 56.7 W cw from a 19-element single bar with an M2 of 1.4  (in horizontal direction)×11.6  (in vertical direction). These parameters are good evidence that all the beams from the diode laser bar are combined together to increase the brightness.

  19. Triggering GaAs lock-on switches with laser diode arrays

    SciTech Connect

    Loubriel, G.M.; Buttram, M.T.; Helgeson, W.D.; McLaughlin, D.L.; O'Malley, M.W.; Zutavern, F.J. ); Rosen, A.; Stabile, P.J. )

    1990-01-01

    Laser diode arrays have been used to trigger GaAs Photoconducting Semiconductor Switches (PCSS) charged to voltages of up to 60 kV and conducting currents of 580 A. The driving forces behind the use of laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays can trigger GaAs at high fields as the result of a new switching mode (lock-on) with very high carrier number gain. We have achieved switching of up to 10 MW in a 60 {Omega} system, with a pulse rise time of 500 ps. At 1.2 MW we have achieved repetition rates of 1 kHz with switch rise time of 500 ps for 10{sup 5} shots. The laser diode array used for these experiments delivers a 166 W pulse. In a single shot mode we have switched 4 kA with a flash lamp pumped laser and 600 A with the 166 W array. 7 refs., 5 figs.

  20. Near-IR diode laser absorption for measurement of tropospheric HO2

    NASA Technical Reports Server (NTRS)

    Stanton, Alan C.

    1994-01-01

    The possibility of using tunable lead salt diode lasers in the infrared for measurement of tropospheric HO2 has been frequently considered. Although the sensitivity of diode laser absorption has been improved through the use of high frequency detection techniques, nature has been unkind in that the HO2 absorption cross sections are weak. Even using the most optimistic assumptions about attainable path length and detectable absorbance, measurement of tropospheric HO2 by diode laser absorption in the mid-IR appears marginal. A possible alternative method for measuring HO2 is by absorption at near-infrared wavelengths. Several absorption bands of HO2 occur in the wavelength region between 1.2 and 1.6 micron due to electronic transitions and overtones of the fundamental vibrational modes. InGaAsP diode lasers operate in this wavelength region and can be used for high resolution spectroscopy in a manner analogous to the lead salt lasers. A diode laser system in the near-IR offers some advantages.