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Sample records for 405-nm diode laser

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  2. Surgical effects on soft tissue produced by a 405-nm violet diode laser in vivo

    NASA Astrophysics Data System (ADS)

    Miyazaki, H.; Kato, J.; Kawai, S.; Hatayama, H.; Uchida, K.; Otsuki, M.; Tagami, J.; Yokoo, S.

    2011-12-01

    This study evaluated the surgical performance of a 405-nm diode laser in vivo, using living rat liver tissue. Tissue was incised by irradiation with the laser at low output power ranging from 1 W (722 W/cm2) to 3 W (2165 W/cm2) on a manual control at a rate of 1 mm/s. As a control, incisions using a stainless scalpel were compared. Immediately after operation, the surface of the incisions was macroscopically observed and histopathologically evaluated by microscopy. Laser-ablated liver tissue was smooth with observable signs of remnant carbonization and easily acquired hemostasis. The thickness of the denatured layer increased in proportion to the output power; the coagulation layer did not thicken accordingly. Bleeding could not be stopped for tissues incised with the stainless scalpel. The 405-nm diode laser thus proved to be effective for ablating soft tissue with high hemostatic ability at low power.

  3. Characterization of AlInGaN-based 405nm distributed feedback laser diodes

    NASA Astrophysics Data System (ADS)

    Masui, S.; Tsukayama, K.; Yanamoto, T.; Kozaki, T.; Nagahama, S.; Mukai, T.

    2008-02-01

    The first-order AlInGaN 405 nm distributed feed-back (DFB) laser diodes were grown on the low dislocation freestanding GaN substrates by a metal organic chemical vapor deposition method. The first-order diffractive grating whose period was 80 nm was formed into an n-type cladding layer. The fine tooth shape grating was obtained by the EB lithography and the dry etching. No additional threading dislocation could be found at the regrowth interface. As a result, we succeeded in demonstrating the first-order AlInGaN based 405 nm DFB laser diodes under cw operation. The threshold current and the slope efficiency were 22 mA and 1.44 W/A under continuous wave operation at 25 °C, respectively. The single longitudinal mode emission was maintained up to an output power of 60 mW. The fundamental transverse mode operation with a single longitudinal mode was observed in the temperature range from 15 °C to 85 °C at an output power of 30 mW. The lifetime was estimated to be 4000 h by the lifetime test which was carried out under the condition of a constant output power of 30mW at 25 °C for 1000 h. The single longitudinal mode emission was maintained for the life tested DFB laser diodes.

  4. Bleaching effect of a 405-nm diode laser irradiation used with titanium dioxide and 3.5% hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Sakai, K.; Kato, J.; Nakazawa, T.; Hirai, Y.

    2007-09-01

    A 405-nm diode laser has recently been developed for soft tissue problems in dentistry. A new in-office bleaching agent consisting of a titanium dioxide photocatalyst and 3.5% hydrogen peroxide has proven to react well with light irradiated at a wavelength of around 400 nm. In this study, we evaluated the bleaching efficacy of a newly developed 405-nm diode laser on bovine teeth treated with a bleaching agent composed of titanium dioxide and 3.5% hydrogen peroxide. Sixteen bovine incisors were randomly divided into two groups: Group A, irradiated by the 405-nm diode laser at 200 mW; Group B, irradiated by the 405-nm diode laser at 400 mW. The bleaching agent with titanium dioxide and 3.5% hydrogen peroxide was applied to bovine enamel and irradiated for 1 min. The specimens were then washed and dried, and the same procedure was repeated nine more times. After irradiation, we assessed the effects of bleaching on the enamel by measuring the color of the specimens with a spectrophotometer and examining the enamel surfaces with a scanning electron microscope. L* rose to a high score, reaching a significantly higher post-treatment level in comparison to pretreatment. In a comparison of the color difference (Δ E) between Group A and Group B, the specimens in Group B showed significantly higher values after 10 min of irradiation for the post-treatment. No remarkable differences in the enamel surface morphology were found between the unbleached and bleached enamel. The use of a 405-nm diode laser in combination with a bleaching agent of titanium dioxide and 3.5% hydrogen peroxide may be an effective method for bleaching teeth without the risk of tooth damage.

  5. Waveguide structural effect on ripples of far-field pattern in 405-nm GaN-based laser diodes

    NASA Astrophysics Data System (ADS)

    Hwang, Sungmin; Shim, Jongin; Ryu, Hanyoul; Ha, Kyung-ho; Chae, Junghye; Nam, Okhyun

    2006-09-01

    We investigated the dependency of waveguide structures on ripples of far-field patterns in 405nm GaN-based laser diodes theoretically and experimentally. As the n-type cladding layer thickness decreases, the passive waveguide modes strongly interact with an active layer mode. This suggests that the thicknesses of n-AlGaN/GaN superlattice clad and n-GaN waveguide layers have significant influences on FFP ripples. We successfully obtained very smooth far-field patterns perpendicular to the junction plane by optimizing both n-AlGaN/GaN clad layer thickness and n-GaN waveguide layer thickness.

  6. 405 nm diode laser, halogen lamp and LED device comparison in dental composites cure: an “in vitro” experimental trial

    PubMed Central

    Fornaini, C.; Merigo, E.; Rocca, J-P.; Chiusano, M.; Cucinotta, A.

    2015-01-01

    Background and aims: A 405 nm diode laser is indicated for composite materials polymerizing, thanks to the recent evolution in their compositions, absorbing in blue part of the spectrum. The purpose of this research was to evaluate its performance on two different kinds of composite resins. Materials and methods: Two different composites were polymerized with a traditional halogen lamp, a LED device and a 405 nm diode laser. The depth of the cure, the volumetric shrinkage, and the degree of the conversion (DC%) of the double bond during the curing process were measured. One-way ANOVA test, Kruskal-Wallis tests, and Dunn comparison tests were used for statistic analysis. Results: Regarding the depth of polymerization, the laser had the worst performance on one composite while on the other, no significant difference with the other devices was observed. The volumetric shrinkage showed that laser produced the lowest change in both of the composites. The DC% measure confirmed these findings. Conclusions: Based on the results of this preliminary study, it is not possible to recommend the 405 nm diode laser for the polymerization of dental composites. PMID:26877591

  7. 9nm node wafer defect inspection using three-dimensional scanning, a 405nm diode laser, and a broadband source

    NASA Astrophysics Data System (ADS)

    Zhou, Renjie; Edwards, Chris; Bryniarski, Casey A.; Popescu, Gabriel; Goddard, Lynford L.

    2015-03-01

    We recently built a 405nm laser based optical interferometry system for 9nm node patterned wafer defect inspection. Defects with volumes smaller than 15nm by 90nm by 35nm have been detected. The success of defect detection relied on accurate mechanical scanning of the wafer and custom engineered image denoising post-processing. To further improve the detection sensitivity, we designed a higher precision XYZ scanning stage and replaced the laser source with an incoherent LED to remove the speckle noise. With these system modifications, we successfully detected both defects and surface contamination particles in bright-field imaging mode. Recently, we have upgraded this system for interferometric defect inspection.

  8. Surface and bulk effects in silica fibers caused by 405 nm CW diode laser irradiation and means for mitigation

    NASA Astrophysics Data System (ADS)

    Gonschior, C. P.; Klein, K.-F.; Sun, T.; Grattan, K. T. V.

    2012-11-01

    Surface and bulk effects in silica optics due to high intensity laser light are well known using short pulse and high power laser systems. Surfaces are quickly destroyed mechanically if not properly prepared and thoroughly cleaned. Linear and non-linear absorption of high intensity laser light in the bulk of the optics causes material modifications, like voids, cracks and UV defects. In ablation experiments with very short pulses on wide band-gap dielectrics, periodic surface structures in the form of ripples were found. Surprisingly, we found similar structures on fiber end-faces after long-term irradiation with 405 nm CW laser light. Power densities on the end-face are in the range of 1 MW/cm2, three magnitudes of order below the power threshold at which the described damages occur. Nevertheless a ripple structure perpendicular to the polarization direction of the laser was formed and grows with irradiation time. An increased absorption band at 214 nm (E' center) along the fiber was discovered by spectral absorption measurements. E' centers can be generated by 405 nm laser light in the bulk, therefore defects on the surface are possible as well. The generation of defect centers on the silica surface can enhance the formation of an unstable surface layer.

  9. High-Density Recording on a Phase-Change Rewritable Disk using a 405 nm Blue Laser Diode

    NASA Astrophysics Data System (ADS)

    Shoji, Mamoru; Nakamura, Atsushi; Miyashita, Harumitsu; Minamino, Jun-ichi; Furumiya, Shigeru; Ishida, Takashi; Ishibashi, Hiromichi

    2002-03-01

    The possibility of a 28 GB capacity/layer has been studied using a blue laser diode and high-NA objective lens. Under the conditions of the disk diameter of 120 mm, cover layer thickness of 0.1 mm, track pitch of 0.32 μm and data bit length of 0.104 μm/bit, a low bit error rate (ber) of 10-5 was obtained in both modulations of D8-15 and RLL(1,7) with partial response maximum likelihood (PRML). A wide tilt margin comparable to that in the case of DVD-RAM was obtained in RLL(1,7).

  10. A new non-vital tooth bleaching method using titanium dioxide and 3.5% hydrogen peroxide with a 405-nm diode laser or a halogen lamp

    NASA Astrophysics Data System (ADS)

    Suemori, T.; Kato, J.; Nakazawa, T.; Akashi, G.; Hirai, Y.

    2008-06-01

    To establish a safer and more effective bleaching method for discolored pulpless teeth, we examined bleaching from the pulpal dentin side using a 3.5% hydrogen peroxide solution containing titanium dioxide. The twenty bovine blood-stained discolored enamel-dentin plates of 1.0 mm enamel thickness and 2.0 mm dentin thickness were used. The bleaching agent was applied to the dentin side that was then irradiated with a 405-nm diode laser (800 mW/cm2) or a halogen lamp (720 mW/cm2) for 15 minutes. The bleaching effect was assessed by spectrophotometric measurement of the color of the specimens from the dentin and enamel side for every 5 minutes, and then dentin or enamel surface was examined with a scanning electron microscope. The 3.5% hydrogen peroxide solution containing titanium dioxide proved to have a strong bleaching effect. The color difference after laser irradiation was higher than that after halogen lamp irradiation, however, there was no significant difference between them. No changes in the enamel surface morphology were found and open dentinal tubules with no smear layer were clearly observed at the pulpal dentin surface in both groups.

  11. Effect of titanium dioxide and 3.5% hydrogen peroxide with 405-nm diode laser irradiation on bonding of resin to pulp chamber dentin

    NASA Astrophysics Data System (ADS)

    Haruyama, A.; Kato, J.; Kameyama, A.; Hirai, Y.; Oda, Y.

    2010-04-01

    This study was conducted to determine the effect of a 3.5% hydrogen peroxide solution containing titanium dioxide on bonding of resin to pulp chamber dentin. Extracted bovine anterior teeth were allocated to three groups of ten teeth each. The coronal labial pulp chamber dentin was exposed and bleached with 3.5% hydrogen peroxide with titanium dioxide with 405-nm diode laser irradiation for 15 min (Group 1); 30% hydrogen peroxide with halogen lamp irradiation for 15 min (Group 2); and distilled water for 15 min (Group 3). After bleaching, the pulp chamber dentin was prepared for composite resin bonding and the interface between the resin and dentin was observed by scanning electron microscopy. The microtensile bond strength (μTBS) and failure patterns were determined. The μTBS values (mean ± SD) were: 17.28 ± 5.79 MPa ( n = 36), 0 MPa, and 26.50 ± 9.83 MPa ( n = 36) in Groups 1, 2, and 3, respectively. The μTBS in Group 3 was significantly higher than that in Group 1 ( P < 0.05). Hybrid layers and resin tags were clearly observed at the interface in Groups 1 and 3, but not in Group 2. Adhesive failure was mainly observed in Group 1, whereas dentin failure was the main failure pattern in Group 3.

  12. The relative antimicrobial effect of blue 405 nm LED and blue 405 nm laser on methicillin-resistant Staphylococcus aureus in vitro.

    PubMed

    Masson-Meyers, Daniela Santos; Bumah, Violet Vakunseh; Biener, Gabriel; Raicu, Valerica; Enwemeka, Chukuka Samuel

    2015-12-01

    It has long been argued that light from a laser diode is superior to light from a light-emitting diode (LED) in terms of its effect on biological tissues. In order to shed light on this ongoing debate, we compared the antimicrobial effect of light emitted from a 405-nm LED with that of a 405-nm laser on methicillin-resistant Staphylococcus aureus (MRSA) at comparable fluences. We cultured 5 × 10(6) CFU/ml MRSA on tryptic soy agar and then irradiated culture plates once, twice, or thrice with either LED or laser light using 40, 54, 81, or 121 J/cm(2) fluence at 15-, 30-, or 240-min time interval between irradiation. Cultures were incubated immediately after irradiation at 37 °C for 24 h before imaging and counting remnant bacterial colonies. Regardless of the device used, LED or laser, irradiation at each fluence resulted in statistically significant bacterial growth suppression compared to non-irradiated controls (p < 0.0001). The antimicrobial effect of both light sources, LED and laser, was not statistically different at each fluence in 35 of the 36 experimental trials. Bacterial growth suppression achieved with either source of light increased with repeated irradiation, particularly at the 15- or 30-min treatment time interval. Thus, we conclude that the antimicrobial effect of 405-nm laser and 405-nm LED on MRSA is similar; neither has a superior antimicrobial effect when compared to the other.

  13. High-speed 405-nm superluminescent diode (SLD) with 807-MHz modulation bandwidth.

    PubMed

    Shen, Chao; Lee, Changmin; Ng, Tien Khee; Nakamura, Shuji; Speck, James S; DenBaars, Steven P; Alyamani, Ahmed Y; El-Desouki, Munir M; Ooi, Boon S

    2016-09-01

    III-nitride LEDs are fundamental components for visible-light communication (VLC). However, the modulation bandwidth is inherently limited by the relatively long carrier lifetime. In this letter, we present the 405 nm emitting superluminescent diode (SLD) with tilted facet design on semipolar GaN substrate, showing a broad emission of ~9 nm at 20 mW optical power. Owing to the fast recombination (τe<0.35 ns) through the amplified spontaneous emission, the SLD exhibits a significantly large 3-dB bandwidth of 807 MHz. A data rate of 1.3 Gbps with a bit-error rate of 2.9 × 10-3 was obtained using on-off keying modulation scheme, suggesting the SLD being a high-speed transmitter for VLC applications. PMID:27607634

  14. Laser photolysis of caged compounds at 405 nm: photochemical advantages, localisation, phototoxicity and methods for calibration.

    PubMed

    Trigo, Federico F; Corrie, John E T; Ogden, David

    2009-05-30

    Rapid, localised photolytic release of neurotransmitters from caged precursors at synaptic regions in the extracellular space is greatly hampered at irradiation wavelengths in the near-UV, close to the wavelength of maximum absorption of the caged precursor, because of inner-filtering by strong absorption of light in the cage solution between the objective and cell. For this reason two-photon excitation is commonly used for photolysis, particularly at multiple points distributed over large fields; or, with near-UV, if combined with local perfusion of the cage. These methods each have problems: the small cross-sections of common cages with two-photon excitation require high cage concentrations and light intensities near the phototoxic limit, while local perfusion gives non-uniform cage concentrations over the field of view. Single-photon photolysis at 405 nm, although less efficient than at 330-350 nm, with present cages is more efficient than two-photon photolysis. The reduced light absorption in the bulk cage solution permits efficient wide-field uncaging at non-toxic intensities with uniform cage concentration. Full photolysis of MNI-glutamate with 100 micros pulses required intensities of 2 mW microm(-2) at the preparation, shown to be non-toxic with repeated exposures. Light scattering at 405 nm was estimated as 50% at 18 microm depth in 21-day rat cerebellum. Methods are described for: (1) varying the laser spot size; (2) photolysis calibration in the microscope with the caged fluorophore NPE-HPTS over the wavelength range 347-405 nm; and (3) determining the point-spread function of excitation. Furthermore, DM-Nitrophen photolysis at 405 nm was efficient for intracellular investigations of Ca2+-dependent processes.

  15. Blue 405 nm laser light mediates heart rate – investigations at the acupoint Neiguan (Pe.6) in Chinese adults

    PubMed Central

    Litscher, Gerhard; Xie, Zheng; Wang, Lu; Gaischek, Ingrid

    2009-01-01

    Background: In previous studies, we showed that laser needle acupuncture with red and infrared light has specific effects on bio-signals of the brain and heart. Aims: In this publication we report the effect of blue laser light on heart rate and heart rate variability (HRV) before, during and after acupuncture at the acupoint Neiguan (Pe.6) in Chinese adults. These are the first data published concerning heart rate and HRV, obtained with blue laser acupuncture equipment. Patients and Methods: The investigations were carried out in 13 healthy Chinese volunteers with a mean age of 31.2 ± 7.5 years within a randomized, controlled study. Stimulation was performed with painless blue laser light (wavelength: 405 nm; activation: 10 minutes) bilaterally at Pe.6. In a second session, for control reasons the laser was not activated. Results: Heart rate showed a significant (p=0.008) decrease during blue laser light stimulation. In contrast, no significant changes were found when the laser was deactivated. The evaluation parameter LF/HF ratio (low frequency/high frequency ratio) from the HRV spectral analysis showed a very slight increase during stimulation, however it was not significant. Conclusions: Our main conclusion is that continuous blue laser light stimulation on Neiguan significantly reduces heart rate of Chinese adults. PMID:22666700

  16. Low-intensity LED (625 and 405 nm) and laser (805 nm) killing of Propionibacterium acnes and Staphylococcus epidermidis

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Tuchin, Valery V.

    2009-02-01

    In the present work we have investigated in vitro sensitivity of microorganisms P. acnes and S. epidermidis to action of red (625 nm and 405 nm) and infrared (805 nm) radiations in combination with photosensitizes Methylene Blue and Indocyanine Green.

  17. Decreased Bone Volume and Bone Mineral Density in the Tibial Trabecular Bone Is Associated with Per2 Gene by 405 nm Laser Stimulation

    PubMed Central

    Yoo, Yeong-Min; Lee, Myung-Han; Park, Ji Hyung; Seo, Dong-Hyun; Lee, Sangyeob; Jung, Byungjo; Kim, Han Sung; Bae, Kiho

    2015-01-01

    Low-level laser therapy/treatment (LLLT) using a minimally invasive laser needle system (MILNS) might enhance bone formation and suppress bone resorption. In this study, the use of 405 nm LLLT led to decreases in bone volume and bone mineral density (BMD) of tibial trabecular bone in wild-type (WT) and Per2 knockout (KO) mice. Bone volume and bone mineral density of tibial trabecular bone was decreased by 405 nm LLLT in Per2 KO compared to WT mice at two and four weeks. To determine the reduction in tibial bone, mRNA expressions of alkaline phosphatase (ALP) and Per2 were investigated at four weeks after 405 nm laser stimulation using MILNS. ALP gene expression was significantly reduced in the LLLT-stimulated right tibial bone of WT and Per2 KO mice compared to the non-irradiated left tibia (p < 0.001). Per2 mRNA expression in WT mice was significantly reduced in the LLLT-stimulated right tibial bone compared to the non-irradiated left tibia (p < 0.001). To identify the decrease in tibial bone mediated by the Per2 gene, levels of runt-related transcription factor 2 (Runx2) and ALP mRNAs were determined in non-irradiated WT and Per2 KO mice. These results demonstrated significant downregulation of Runx2 and ALP mRNA levels in Per2 KO mice (p < 0.001). Therefore, the reduction in tibial trabecular bone resulting from 405 nm LLLT using MILNS might be associated with Per2 gene expression. PMID:26580614

  18. Immunocytochemical studies on the effect of 405-nm low-power laser irradiation on human-derived A-172 glioblastoma cells.

    PubMed

    Ang, Foong Yee; Fukuzaki, Yumi; Yamanoha, Banri; Kogure, Shinichi

    2012-09-01

    The application of low-power laser irradiation (LLI) affects the cell cycle and cell proliferation in various kinds of cells. LLI at a wavelength of 808 nm and a power of 30 mW has been found to significantly decrease the proliferation rate of cells of the human-derived glioblastoma cell line A-172. To determine if this effect of LLI is specific to 808-nm LLI, the present study was designed to reveal the effects of 405-nm LLI under the same experimental conditions. A-172 glioblastoma cells were cultured in 96-well plates according to the conventional protocol. Two different schedules of 405-nm LLI (27 mW) were tested: longer periods of 20, 40 and 60 min and shorter periods of 1, 2, 3, 5, 10 and 15 min. Cells on a digital image displayed on a computer monitor were counted and the proliferation ratio was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) staining. Annexin-V-FLUOS staining and acridine-orange/ethidium-bromide staining were in an immunocytochemical assay to determine if cells were viable or dead (due to apoptosis or necrosis). Cell counting and MTT staining showed that longer 405-nm LLI significantly suppressed the proliferation of A-172 cells at 48 h after LLI (p < 0.05 or p < 0.01) and that the effect of LLI tended to be dose-dependent with morphological changes including cell death. At 90 min after LLI, shorter 405-nm LLI caused necrotic as well as apoptotic cell death, and these effects depended on irradiation time, power and energy density. Detailed analysis revealed that this lethal effect occurred after LLI and was not sustainable. It is concluded that 405-nm LLI has a lethal effect on human-derived glioblastoma A-172 cells, that is different from the suppressive effect without morphological changes induced by 808-nm LLI.

  19. Inhibition of enteric pathogens using integrated high intensity 405 nm LED on the surface of almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogates inoculated onto the surface of almonds. High intensity monochromatic light was generated from an array of narrow-band 405 nm light emitting diodes (LED). Al...

  20. Visible optical radiation generates bactericidal effect applicable for inactivation of health care associated germs demonstrated by inactivation of E. coli and B. subtilis using 405-nm and 460-nm light emitting diodes

    NASA Astrophysics Data System (ADS)

    Hönes, Katharina; Stangl, Felix; Sift, Michael; Hessling, Martin

    2015-07-01

    The Ulm University of Applied Sciences is investigating a technique using visible optical radiation (405 nm and 460 nm) to inactivate health-hazardous bacteria in water. A conceivable application could be point-of-use disinfection implementations in developing countries for safe drinking water supply. Another possible application field could be to provide sterile water in medical institutions like hospitals or dental surgeries where contaminated pipework or long-term disuse often results in higher germ concentrations. Optical radiation for disinfection is presently mostly used in UV wavelength ranges but the possibility of bacterial inactivation with visible light was so far generally disregarded. One of the advantages of visible light is, that instead of mercury arc lamps, light emitting diodes could be used, which are commercially available and therefore cost-efficient concerning the visible light spectrum. Furthermore they inherit a considerable longer life span than UV-C LEDs and are non-hazardous in contrast to mercury arc lamps. Above all there are specific germs, like Bacillus subtilis, which show an inactivation resistance to UV-C wavelengths. Due to the totally different deactivation mechanism even higher disinfection rates are reached, compared to Escherichia coli as a standard laboratory germ. By 460 nm a reduction of three log-levels appeared with Bacillus subtilis and a half log-level with Escherichia coli both at a dose of about 300 J/cm². By the more efficient wavelength of 405 nm four and a half log-levels are reached with Bacillus subtilis and one and a half log-level with Escherichia coli also both at a dose of about 300 J/cm². In addition the employed optical setup, which delivered a homogeneous illumination and skirts the need of a stirring technique to compensate irregularities, was an important improvement compared to previous published setups. Evaluated by optical simulation in ZEMAX® the designed optical element provided proven

  1. Inhibition of enteric pathogens and surrogates using integrated, high intensity 405nm led light on the surface of almonds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The disinfecting properties of 405 nm light were investigated against Escherichia coli O157:H7, Salmonella, and their non-pathogenic surrogate bacteria on the surface of almonds. High intensity monochromatic blue light (MBL) was generated from an array of narrow-band 405 nm light-emitting diodes (LE...

  2. 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.

  3. Study of timing properties of multi-pixel-photon-counter's illuminated by 630 nm and 405 nm PiLas laser light

    SciTech Connect

    Ronzhin, Anatoly; Demarteau, Marcel; Los, Sergey; Ramberg, Erik; /Fermilab

    2009-04-01

    Timing measurements of Multy-Pixel-Photon Counters (MPPC's) at the picosecond level were performed at Fermilab. The core timing resolution of the amplifiers, discriminators and TAC/ADC combination to perform these measurements is approximately 2 picoseconds. The single photoelectron time resolution (SPTR) was measured for the signals coming from the MPPC's. An SPTR of about one hundred picoseconds was obtained for MPPC's illuminated by picosecond laser pulses. The SPTR depends on applied bias voltage and on the wavelength of the light. A simple model is proposed to explain the difference in the SPTR for blue and red light. Finally, requirements for the MPPC's temperature and bias voltage stability to maintain the time resolution are discussed.

  4. 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.

  5. 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.

  6. Comparison of violet diode laser with CO II laser in surgical performance of soft tissues

    NASA Astrophysics Data System (ADS)

    Hatayama, H.; Kato, J.; Inoue, A.; Akashi, G.; Hirai, Y.

    2007-02-01

    The violet diode laser (405nm) has recently begun to be studied for surgical use and authors reported the soft tissue could be effectively incised by irradiation power of even less than 1W. The wavelength of this laser is highly absorbed by hemoglobin, myoglobin or melanin pigment. Cutting or ablating soft tissues by lower irradiation power might be preferable for wound healing. The CO II laser is known to be preferable for low invasive treatment of soft tissues and widely used. The CO II laser light (10.6μm) is highly absorbed by water and proper for effective ablation of soft tissues. In this paper, we report the comparison of the violet diode laser with the CO II laser in surgical performance of soft tissues. Tuna tissue was used as an experimental sample. In the case of the violet diode laser, extensive vaporization of tissue was observed after the expansion of coagulation. Carbonization of tissue was observed after the explosion. On the other hand, consecutive vaporization and carbonization were observed immediately after irradiation in the case of CO II laser. The violet diode laser could ablate tissue equivalently with the CO II laser and coagulate larger area than the CO II laser. Therefore the violet diode laser might be expectable as a surgical tool which has excellent hemostatis.

  7. 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.

  8. Ablation of dentin by irradiation of violet diode laser

    NASA Astrophysics Data System (ADS)

    Hatayama, H.; Kato, J.; Akashi, G.; Hirai, Y.; Inoue, A.

    2006-02-01

    Several lasers have been used for clinical treatment in dentistry. Among them, diode lasers are attractive because of their compactness compared with other laser sources. Near-infrared diode lasers have been practically used for cutting soft tissues. Because they penetrate deep to soft tissues, they cause sufficiently thick coagulation layer. However, they aren't suitable for removal of carious dentin because absorption by components in dentin is low. Recently, a violet diode laser with a wavelength of 405nm has been developed. It will be effective for cavity preparation because dentin contains about 20% of collagen whose absorption coefficient at a violet wavelength is larger than that at a near-infrared wavelength. In this paper, we examined cutting performance of the violet diode laser for dentin. To our knowledge, there have been no previous reports on application of a violet laser to dentin ablation. Bovine teeth were irradiated by continuous wave violet diode laser with output powers in a range from 0.4W to 2.4W. The beam diameter on the sample was about 270μm and an irradiation time was one second. We obtained the crater ablated at more than an output power of 0.8W. The depth of crater ranged from 20μm at 0.8W to 90μm at 2.4W. Furthermore, the beam spot with an output power of 1.7W was scanned at a speed of 1mm/second corresponding to movement of a dentist's hand in clinical treatment. Grooves with the depth of more than 50μm were also obtained. From these findings, the violet diode laser has good potential for cavity preparation. Therefore, the violet diode laser may become an effective tool for cavity preparation.

  9. Absolute measurements of total peroxy nitrate mixing ratios by thermal dissociation blue diode laser cavity ring-down spectroscopy.

    PubMed

    Paul, Dipayan; Osthoff, Hans D

    2010-08-01

    Peroxycarboxylic nitric anhydrides (PANs) have long been recognized as important trace gas constituents of the troposphere. Here, we describe a blue diode laser thermal dissociation cavity ring-down spectrometer for rapid and absolute measurements of total peroxyacyl nitrate (SigmaPAN) abundances at ambient concentration levels. The PANs are thermally dissociated and detected as NO2, whose mixing ratios are quantified by optical absorption at 405 nm relative to a reference channel kept at ambient temperature. The effective NO2 absorption cross-section at the diode laser emission wavelength was measured to be 6.1 x 10(-19) cm2 molecule(-1), in excellent agreement with a prediction based on a projection of a high-resolution literature absorption spectrum onto the laser line width. The performance, i.e., accuracy and precision of measurement and matrix effects, of the new 405 nm thermal dissociation cavity ring-down spectrometer was evaluated and compared to that of a 532 nm thermal dissociation cavity ring-down spectrometer using laboratory-generated air samples. The new 405 nm spectrometer was considerably more sensitive and compact than the previously constructed version. The key advantage of laser thermal dissociation cavity ring-down spectroscopy is that the measurement can be considered absolute and does not need to rely on external calibration.

  10. Non-linear photoacoustic and fluorescence microscopy using a modulated laser diode

    NASA Astrophysics Data System (ADS)

    Langer, G.; Berer, T.

    2016-03-01

    We present simultaneous photoacoustic and fluorescence microscopy using a modulated laser diode. Photoacoustic waves and modulated fluorescence are generated by using a laser diode with a wavelength of 405nm at modulation frequencies in the Megahertz range. Additionally, a continuous wave offset radiation can be superposed. The excitation light is focused to the sample using a high NA objective. Luminescence is collected by the same objective in a confocal configuration and measured by an avalanche photo diode. Photoacoustic waves are recorded on the opposite site of the sample using a hydrophone. Acoustic and luminescence signals are recorded using a lock-in technique. We present photoacoustic imaging on red blood cells and multimodal imaging on fluorescent microspheres. Nonlinear photoacoustic and luminescence effects were introduced with the help of a superposed continuous wave laser.

  11. Blue diode laser: a new approach in oral surgery?

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Selleri, Stefano; Cucinotta, Annamaria

    2016-02-01

    The introduction of diode lasers in dentistry had several advantages, principally consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibbers. Up today two diode wavelengths, 810 and 980 nm, were the most utilized in oral surgery but recently a new wavelength emitting in the blue had been proposed. The aim of this ex vivo study was to compare the efficacy of five laser wavelengths (450, 532, 808, 1064 and 1340 nm) for the ablation of soft tissues. Specimens were surgically collected from the dorsal surface of four bovine tongues and irradiated by the five different wavelengths. Thermal increase was measured by two thermocouples, the first at a depth of 0.5 mm, and the second at a depth of 2 mm while initial and final surface temperatures were recorded by IR thermometer. The quality of the incision was histologically evaluated by a pathologist by giving a score from 0 to 5. The time necessary to perform the excision varied between 215 seconds (1340 nm, 5W) and 292 seconds (808 nm, 3W). Surface temperature increase was highest for 1340 nm, 5W and lowest for 405 nm, 4 W. The most significant deep temperature increase was recorded by 1340 nm, 5 W and the lowest by 450 nm, 2 W. The quality of incision was better and the thermal elevation lower in the specimens obtained with shortest laser wavelength (450 nm).

  12. Semiconductor laser diode

    SciTech Connect

    Amann, M.C.

    1982-09-28

    A semiconductor laser diode is disclosed with a connection electrode consisting of a chromium/gold alloy on a highly-doped gallium arsenide layer. The gallium arsenide layer is strip shaped and overlies a further lesser doped layer of gallium aluminum arsenide. The chromium/gold contact has a low-resistance junction only in the region of the more highly doped layer so that a strip shaped restriction of the current path occurs in the semiconductor body. Accordingly, a laser-active zone which is only strip-shaped is achieved.

  13. Making an ultrastable diode laser

    NASA Astrophysics Data System (ADS)

    Archibald, James; Washburn, Matt; van Zijll, Marshall; Erickson, Christopher; Neyenhuis, Brian; Doermann, Greg; Durfee, Dallin

    2006-10-01

    We have constructed a 657nm diode laser with excellent stability for use in an atom interferometer. The laser is a grating-stabilized diode laser is locked to a high-finesse cavity using the Pound-Drever-Hall method. We have measured a linewidth of about 1 kHz and are working on several improvements which should further reduce our linewidth.

  14. Diode laser applications in urology

    NASA Astrophysics Data System (ADS)

    Sam, Richard C.; Esch, Victor C.

    1995-05-01

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

  15. Diode-pumped dye laser

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.

  16. Characterization of Stock Blu-ray diodes

    NASA Astrophysics Data System (ADS)

    Cunningham, Mark; Archibald, James; Erickson, Christopher; Durfee, Dallin

    2010-10-01

    I am developing a process to test and characterize diodes of unknown wavelengths. using a B&WTEK Spectrometer we are characterizing the wavelength of 405 nm blu-ray diodes purchased in bulk. With the known error in production of the Diode Lasers we are hoping to find a diode at 408 nm to use in driving a raman transition between hyperfine states of strontium 87 ions. The bulk of the project is a java program that communicates with the spectrometer and graphically displays the intensities of the wavelengths from the laser diodes.

  17. Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

    NASA Astrophysics Data System (ADS)

    Komori, Yuichi; Ishii, Yukihiro

    2010-08-01

    A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Inactivation of Streptomyces phage ɸC31 by 405 nm light: Requirement for exogenous photosensitizers?

    PubMed

    Tomb, Rachael M; Maclean, Michelle; Herron, Paul R; Hoskisson, Paul A; MacGregor, Scott J; Anderson, John G

    2014-01-01

    Exposure to narrowband violet-blue light around 405 nm wavelength can induce lethal oxidative damage to bacteria and fungi, however effects on viruses are unknown. As photosensitive porphyrin molecules are involved in the microbicidal inactivation mechanism, and since porphyrins are absent in viruses, then any damaging effects of 405 nm light on viruses might appear unlikely. This study used the bacteriophage ɸC31, as a surrogate for non-enveloped double-stranded DNA viruses, to establish whether 405 nm light can induce virucidal effects. Exposure of ɸC31 suspended in minimal media, nutrient-rich media, and porphyrin solution, demonstrated differing sensitivity of the phage. Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm(2), respectively. When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm(2): much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media. This study provides the first evidence of the interaction of narrowband 405 nm light with viruses, and demonstrates that viral susceptibility to 405 nm light can be significantly enhanced by involvement of exogenous photosensitive components. The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms. PMID:25101216

  3. Inactivation of Streptomyces phage ɸC31 by 405 nm light

    PubMed Central

    Tomb, Rachael M; Maclean, Michelle; Herron, Paul R; Hoskisson, Paul A; MacGregor, Scott J; Anderson, John G

    2014-01-01

    Exposure to narrowband violet-blue light around 405 nm wavelength can induce lethal oxidative damage to bacteria and fungi, however effects on viruses are unknown. As photosensitive porphyrin molecules are involved in the microbicidal inactivation mechanism, and since porphyrins are absent in viruses, then any damaging effects of 405 nm light on viruses might appear unlikely. This study used the bacteriophage ɸC31, as a surrogate for non-enveloped double-stranded DNA viruses, to establish whether 405 nm light can induce virucidal effects. Exposure of ɸC31 suspended in minimal media, nutrient-rich media, and porphyrin solution, demonstrated differing sensitivity of the phage. Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm2, respectively. When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm2: much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media. This study provides the first evidence of the interaction of narrowband 405 nm light with viruses, and demonstrates that viral susceptibility to 405 nm light can be significantly enhanced by involvement of exogenous photosensitive components. The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms. PMID:25101216

  4. 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.

  5. High-power laser diodes, laser diode modules, and their applications

    NASA Astrophysics Data System (ADS)

    Daiminger, Franz X.; Dorsch, Friedhelm; Lorenzen, Dirk

    1998-12-01

    High power laser diodes and especially high power laser diode modules made enormous progress in the last few years. Different aspects of high power laser diodes are treated starting from general description of high power laser diodes and their mounting techniques, characterizing the electro- optical behavior of single laser bars and finally presenting beamshaping optics for the collimation of large modules. The later technique allows for symmetrical focal spots in the kilowatt range with a beam quality of about 170 mm*mrad. Different aspects of current applications of high power laser diodes are presented.

  6. Physics and applications of laser diode chaos

    NASA Astrophysics Data System (ADS)

    Sciamanna, M.; Shore, K. A.

    2015-03-01

    This Review Article provides an overview of chaos in laser diodes by surveying experimental achievements in the area and explaining the theory behind the phenomenon. The fundamental physics underpinning laser diode chaos and also the opportunities for harnessing it for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient testbed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.

  7. 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.

  8. 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.

  9. Real-time vapor detection of nitroaromatic explosives by catalytic thermal dissociation blue diode laser cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Taha, Youssef M.; Odame-Ankrah, Charles A.; Osthoff, Hans D.

    2013-09-01

    A compact blue diode laser catalytic thermal dissociation cavity ring-down spectrometer (cTD-CRDS) to detect vapors of nitroaromatic explosives is described. The instrument uses heated platinum(IV) oxide catalyst to convert nitroaromatic compounds to NO2, which is detected at 405 nm. Using the relatively volatile nitrobenzene as a test compound, we show by Fourier Transform Infrared Spectroscopy (FTIR) in off-line experiments that nitroaromatics can be quantitatively converted to NO2. The cTD-CRDS detection limit was 0.3 parts-per-billion by volume (ppbv) and sufficiently low to allow the detection of a room temperature sample of 2,4,6-trinitrotoluene (TNT) without sample preconcentration.

  10. Laser diode package with enhanced cooling

    DOEpatents

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

    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.

  11. 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.

  12. Laser diode package with enhanced cooling

    DOEpatents

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

    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.

  13. 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)

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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%.

  3. 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.

  4. 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.

  5. 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.

  6. Spatial Dosimetry with Violet Diode Laser-Induced Fluorescence of Water-Equivalent Radio-Fluorogenic Gels

    NASA Astrophysics Data System (ADS)

    Sandwall, Peter A., II

    The following work describes investigations of spatial dosimetry using laser-induced fluorescence of a radio-fluorogenic detector embedded within water-equivalent media. The chemical composition of a gelatin-based coumarin-3-carboxylic acid detector was investigated and dose response characterized. Violet diode (405nm) excitation sources were explored and laser-induced fluorescence (LIF) employed to obtain the pattern of fluorescent emission yielding images of the integrated spatial dose distribution. The design of a three-dimensional reader is proposed to provide a foundation for future work. Radio-fluorogenic processes create fluorescent products in response to ionizing radiation. Water radiolysis produced by ionizing radiation yields hydroxyl free radicals that readily hydroxylate coumarin-3-carboxylic acid to 7-hydroxy-coumarin-3-carboxylic acid, a derivative of umbelliferone. Umbelliferone is a known fluorophore, exhibiting peak excitation in the UV to near UV range of 365-405nm with a visible 445nm blue emission. Coumarin-3-carboxlyic acid has been studied in an aqueous gelatin matrix. The radio-fluorogenic coumarin-gelatin detector has been shown to respond to an absorbed dose of ionizing radiation in a measureable manner. The detector was studied with respect to concentration of gelatin and coumarin in the presence of pH buffers. Dose response of the detector was investigated with regard to ionizing radiation type, energy, and rate of irradiation. Results demonstrate a functional detector. Patterns of energy deposition were formed in response to ionizing radiation produced by a sealed-source of radioactive Ir-192 embedded in the gelatin matrix of the detector. Spatial distributions of absorbed dose were recorded and analyzed as a function of fluorescent emission. The distribution of energy deposition was imaged with LIF excitation by a divergent beam of 405nm light and determined by analysis of digital image pixel intensity values displaying the 445nm

  7. Determining Extinction Ratio Of A Laser Diode

    NASA Technical Reports Server (NTRS)

    Unger, Glenn L.

    1992-01-01

    Improved technique to determine extinction ratio of pulsed laser diode based partly on definition of extinction ratio applicable to nonideal laser pulses. Heretofore, determinations involved assumption of ideal laser pulses, and neglected optical power from background light. Because power fluctuates during real pulse, more realistic to define extinction ratio in terms of energy obtained.

  8. 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.

  9. Blood sugar monitoring with laser diode

    NASA Astrophysics Data System (ADS)

    Zhang, Xiqin; Chen, Jianhong; Yeo, Joon Hock

    2006-09-01

    In this paper, the non-invasive measurement of blood sugar level was studied by use of near infrared laser diode. The in-vivo experiments were carried out using laser diodes with wavelength 1625nm and 1650nm. Several volunteers were tested before and after drinking glucose solution. We took blood from a fingertip and measured its concentration with a glucose meter while taking signal voltage from laser diode system. The signal voltage was processed by using a computer and blood absorption was obtained. The results show that blood sugar level and blood absorption have similar trends before and after drinking glucose solution. We also compared the trends of drinking glucose solution and pure water and the results show that the difference of blood absorption is obvious. From the results we can see that laser diode is suitable for blood glucose monitoring.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Diode laser photocoagulation for diabetic macular oedema.

    PubMed Central

    Ulbig, M W; McHugh, D A; Hamilton, A M

    1995-01-01

    AIMS--This study aimed to investigate whether diode laser irradiation, which is poorly absorbed by haemoglobin, can induce closure of leaking retinal microvascular lesions in the treatment of diabetic macular oedema. METHODS--Thirty three eyes with clinically significant diabetic macular oedema were treated with a diode laser. Fundus evaluation before and after treatment included visual acuity, stereoscopic biomicroscopy, colour photographs, and fluorescein angiography. RESULTS--At a mean period of review of 6 months macular oedema had completely or partially resolved in 27 eyes. Visual acuity improved in three, deteriorated in one, and was unchanged in 29 eyes. CONCLUSION--Preliminary data suggest that diode laser therapy induces closure of leaking retinal microaneurysms and is effective in the treatment of diabetic macular oedema. Images PMID:7742274

  19. 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.

  20. 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.

  1. Cytotoxic responses to 405nm light exposure in mammalian and bacterial cells: Involvement of reactive oxygen species.

    PubMed

    Ramakrishnan, Praveen; Maclean, Michelle; MacGregor, Scott J; Anderson, John G; Grant, M Helen

    2016-06-01

    Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to 405 nm light at 36 J/cm(2) (a bactericidal dose) had no significant effect on normal cell function, although at higher doses (54 J/cm(2)), mammalian cell death became evident. This research demonstrates that mammalian and bacterial cell toxicity induced by 405 nm light exposure is accompanied by reactive oxygen species production, as detected by generation of fluorescence from 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate. As indicators of the resulting oxidative stress in mammalian cells, a decrease in intracellular reduced glutathione content and a corresponding increase in the efflux of oxidised glutathione were observed from 405 nm light treated cells. The mammalian cells were significantly protected from dying at 54 J/cm(2) in the presence of catalase, which detoxifies H2O2. Bacterial cells were significantly protected by sodium pyruvate (H2O2 scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (OH scavenger) and catalase) at 162 and 324 J/cm(2). Results therefore suggested that the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria could be oxidative stress involving predominantly H2O2 generation, with other ROS contributing to the damage.

  2. Performance and lifetime of high-power diode lasers and diode laser systems

    NASA Astrophysics Data System (ADS)

    Dorsch, Friedhelm; Daiminger, Franz X.

    1999-04-01

    High-power diode lasers have reached output power and reliability to meet requirements for industrial applications. Stacking of laser elements to modules increases the output power, beam shaping techniques allow to focus the radiation of a module to a single spot. An integrated diode laser systems with totally 50 laser bars is shown, that includes cooling, power supply and control unit. The laser radiation is transmitted by an optical fiber and an objective focuses the radiation onto the workpiece with a round spot of less than 1 mm diameter and cw power of more than 1 kW.

  3. Environmental testing of a diode-laser-pumped Nd:YAG laser and a set of diode-laser-arrays

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Lesh, J. R.

    1989-01-01

    Results of the environmental test of a compact, rigid and lightweight diode-laser-pumped Nd:YAG laser module are discussed. All optical elements are bonded onto the module using space applicable epoxy, and two 200 mW diode laser arrays for pump sources are used to achieve 126 mW of CW output with about 7 percent electrical-to-optical conversion efficiency. This laser assembly and a set of 20 semiconductor diode laser arrays were environmentally tested by being subjected to vibrational and thermal conditions similar to those experienced during launch of the Space Shuttle, and both performed well. Nevertheless, some damage to the laser front facet in diode lasers was observed. Significant degradation was observed only on lasers which performed poorly in the life test. Improvements in the reliability of the Nd:YAG laser are suggested.

  4. 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.

  5. 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.

  6. 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

  7. Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

    NASA Astrophysics Data System (ADS)

    Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

    2016-04-01

    5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

  8. Diode laser saturation spectroscopy of NH3

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.

    1978-01-01

    Saturation of molecular transitions using a tuneable diode laser was demonstrated for the first time using a standing-wave cavity configuration with an f/8 beam focussed at the sample. Observed saturation effects in NH3 transitions near 888/cm include sub-Doppler (Lamb-dip) resonances at line center.

  9. 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.

  10. 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.

  11. Photodynamic action on microorganisms using iron oxide Fe2O3 nanoparticles and LED blue (405 nm) light

    NASA Astrophysics Data System (ADS)

    Petrov, Pavel O.; Kulikova, Maria V.; Tuchina, Elena S.; Kochubey, Vyacheslav I.; Tuchin, Valery V.

    2012-03-01

    The main goal was to study the sensitivity of microorganisms to combined action of LED blue (405 nm) light and Fe2O3 nanoparticles. The bacterial strains used in this study were Staphylococcus aureus 209 P, S. simulans, Dermabacter hominis (isolated from maxillary sinusitis). As blue light source LED with spectrum maxima at 405 nm was taken. The light exposure was ranged from 5 to 30 min. Fe2O3 nanoparticles with average size about 8 nm in concentration of 0.001% were used. It was shown that irradiation with blue light caused 20 to 90% decrease in the number of microorganisms treated with nanoparticles.

  12. High-power direct-diode laser successes

    NASA Astrophysics Data System (ADS)

    Haake, John M.; Zediker, Mark S.

    2004-06-01

    Direct diode laser will become much more prevalent in the solar system of manufacturing due to their high efficiency, small portable size, unique beam profiles, and low ownership costs. There has been many novel applications described for high power direct diode laser [HPDDL] systems but few have been implemented in extreme production environments due to diode and diode system reliability. We discuss several novel applications in which the HPDDL have been implemented and proven reliable and cost-effective in production environments. These applications are laser hardening/surface modification, laser wire feed welding and laser paint stripping. Each of these applications uniquely tests the direct diode laser systems capabilities and confirms their reliability in production environments. A comparison of the advantages direct diode laser versus traditional industrial lasers such as CO2 and Nd:YAG and non-laser technologies such a RF induction, and MIG welders for each of these production applications is presented.

  13. Four channel Laser Firing Unit using laser diodes

    NASA Technical Reports Server (NTRS)

    Rosner, David, Sr.; Spomer, Edwin, Sr.

    1994-01-01

    This paper describes the accomplishments and status of PS/EDD's (Pacific Scientific/Energy Dynamics Division) internal research and development effort to prototype and demonstrate a practical four channel laser firing unit (LFU) that uses laser diodes to initiate pyrotechnic events. The LFU individually initiates four ordnance devices using the energy from four diode lasers carried over the fiber optics. The LFU demonstrates end-to-end optical built in test (BIT) capabilities. Both Single Fiber Reflective BIT and Dual Fiber Reflective BIT approaches are discussed and reflection loss data is presented. This paper includes detailed discussions of the advantages and disadvantages of both BIT approaches, all-fire and no-fire levels, and BIT detection levels. The following topics are also addressed: electronic control and BIT circuits, fiber optic sizing and distribution, and an electromechanical shutter type safe/arm device. This paper shows the viability of laser diode initiation systems and single fiber BIT for typing military applications.

  14. Design of laser diode stable output system

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Cao, Rui-ming

    2008-03-01

    High-stability output's system of laser diode is introduced in this paper. The system which is based on the MCU of MSP430 has been designed light power feedback loop and coller of TEC. It includes stable current, protecting circuit, light power feedback loop, temperature controlling, power display and so on. It is also able to control and show the power at the real time. The power could be set by botton too. The software of slow start up, slow close and the protecting relay are adopted by MCU. DRV592 is introduced as PWM driver to control the current of TEC. The duty cycle is generate by MCU. In order to control temperature, it is changed to influence the current of TEC. The power that is sampled by photodiode which is integrated in the laser diode is controlled by the micro-processing. The laser is monitored by voltage control circuit and current control circuit at the real time.

  15. 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.

  16. Diode laser pumped solid state laser with 2 micrometer wavelength

    NASA Astrophysics Data System (ADS)

    Hansson, G.; Callenas, A.

    1994-06-01

    Research at the FOA in the field diode laser pumped solid state lasers with 2 micrometer wavelength is presented. The research was made within the project Antisensor laser. Basic models for CW and pulsed lasers are presented together with results and experience from the design of a diode laser pumped CW laser based on Thulium (Tm), Holmium (Ho) doped Yttrium Lithium Fluoride (TLiF4), abbreviated Tm, Ho:YLF. Measurements on upconversion of energy from the upper laser level in the laser crystal has been made. The upconversion causes loss of energy which leads to higher laser threshold and lower upper state effective lifetime. The result shows less upconversion in Tm, Ho doped YLF than with the same active ions doped into Yttrium Aluminum Garnet (Tm, Ho: YAG). A simple pump configuration was assembled which produced a pump focus of about 200 micrometers radius. With 1 W pump power, an output power of 50 mW was achieved with the laser crystal at room temperature (25 C). With the crystal cooled to 5 C temperature, 77 mW output power was achieved. The measured laser threshold was in good agreement with the calculated value. The efficiency was only 10% compared to the predicted value of 50%. Measurements of laser beam cross section, wavelength and longitudinal laser modes have also been made and is presented in the report.

  17. Wavelength control of visible light laser diodes

    NASA Astrophysics Data System (ADS)

    Goto, N.; Fujii, T.; Nemoto, K.; Suzuki, H.; Nakagawa, K.; Otsu, M.

    1990-04-01

    Wavelength control of visible light laser diodes was studied. By combining an interferometer and a diffraction grating, it became possible to control the wavelength of continuous oscillation in the range of 664 to 673nm, the frequency fine control range being 2GHz. And the spectral linewidth was narrowed to about 44kHz (10 exp minus 7 nm). With the use of a collimator lens, the beam expansion was narrowed to 2mrad. It was confirmed that the pulse output of continuous oscillation visible light laser diodes can be amplified by the YAG laser excitation dye laser. In the case of pulse oscillation, oscillation of 1GHz spectral width was obtained at the wavelength of 0.8 micro m by using an injection synchronization method. In the injection synchronization method, other laser beam is injected in an oscillator and a superior laser beam of synchronized components alone is obtained. As the wavelength control method is now stabilized and satisfies the conditions of narrow band, it has the prospect to be applied to the laser uranium enrichment technology.

  18. Visible fiber lasers excited by GaN laser diodes

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yasushi; Nakanishi, Jun; Yamada, Tsuyoshi; Ishii, Osamu; Yamazaki, Masaaki

    2013-07-01

    This paper describes and discusses visible fiber lasers that are excited by GaN laser diodes. One of the attractive points of visible light is that the human eye is sensitive to it between 400 and 700 nm, and therefore we can see applications in display technology. Of course, many other applications exist. First, we briefly review previously developed visible lasers in the gas, liquid, and solid-state phases and describe the history of primary solid-state visible laser research by focusing on rare-earth doped fluoride media, including glasses and crystals, to clarify the differences and the merits of primary solid-state visible lasers. We also demonstrate over 1 W operation of a Pr:WPFG fiber laser due to high-power GaN laser diodes and low-loss optical fibers (0.1 dB/m) made by waterproof fluoride glasses. This new optical fiber glass is based on an AlF3 system fluoride glass, and its waterproof property is much better than the well known fluoride glass of ZBLAN. The configuration of primary visible fiber lasers promises highly efficient, cost-effective, and simple laser systems and will realize visible lasers with photon beam quality and quantity, such as high-power CW or tunable laser systems, compact ultraviolet lasers, and low-cost ultra-short pulse laser systems. We believe that primary visible fiber lasers, especially those excited by GaN laser diodes, will be effective tools for creating the next generation of research and light sources.

  19. Flight-qualification of a wideband laser diode transmitter module

    NASA Technical Reports Server (NTRS)

    Holcomb, Terry L.; Mecherle, G. S.

    1992-01-01

    A diffraction-limited laser diode transmitter module suitable for wideband direct detection laser communication is described. The transmitter module incorporates a high power semiconductor diode laser, collimating lens, thermal control, and driver circuit in a hermetic enclosure. The module has undergone environmental testing which demonstrates its suitability for space application, and accelerated lifetesting of the laser diode suggests an operational lifetime of nearly ten years.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Novel developments in laser diode Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Claps, Ricardo Javier

    2000-11-01

    This thesis presents the last developments of a laser diode Raman spectrometer for gases, gas flows and vapors, at medium-low pressures. Results are shown for atmospheric gases under STP conditions, and also gas flows from nozzles in subsonic-sonic regimes. The system is unique in that it uses a high power laser diode passively locked by an external grating cavity in Littman/Metcalf configuration, with side-band modes suppressed by 1:10-5, and a reduced bandwidth of <500MHz. The use of Rb vapor cells as notch filters with unprecedented narrow bandwidth (<7 cm-1), allow to collect Stokes and a-Stokes rotational Raman spectra simultaneously. The spectrometer is used to perform studies of thermodynamic equilibrium of gas flows; further studies of samples seeded in the flow (alkali- halides) are discussed, together with potential applications for environmental and industrial monitoring.

  6. Gaseous oxygen detection using laser diodes

    NASA Technical Reports Server (NTRS)

    Fox, Curtis W.; Disimile, Peter J.

    1991-01-01

    Transitions in the R-branch of the O2 A-band have been observed by modulating IR laser diode temperatures; on the basis of these transitions, O2 concentrations as low as 750 ppm can be determined. The transmission measurement's achievable precision correlates with an O2 concentration uncertainty of only 0.5 percent. Both the concentration and the static temperature of the gas are thereby determinable. Improved optics are being designed to improve these performance figures.

  7. 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.

  8. 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.

  9. 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.

  10. Electrostatic Discharge (ESD) Protection for a Laser Diode Ignited Actuator

    SciTech Connect

    SALAS, FREDERICK J.; SANCHEZ, DANIEL H.; WEINLEIN, JOHN HARVEY

    2003-06-01

    The use of laser diodes in devices to ignite pyrotechnics provides unique new capabilities including the elimination of electrostatic discharge (ESD) pulses entering the device. The Faraday cage formed by the construction of these devices removes the concern of inadvertent ignition of the energetic material. However, the laser diode itself can be damaged by ESD pulses, therefore, to enhance reliability, some protection of the laser diode is necessary. The development of the MC4612 Optical Actuator has included a circuit to protect the laser diode from ESD pulses including the ''Fisher'' severe human body ESD model. The MC4612 uses a laser diode and is designed to replace existing hot-wire actuators. Optical energy from a laser diode, instead of electrical energy, is used to ignite the pyrotechnic. The protection circuit is described along with a discussion of how the circuit design addresses and circumvents the historic 1Amp/1Watt requirement that has been applicable to hot-wire devices.

  11. 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.

  12. 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.

  13. A Diode Laser Based Cavity Ring-Down Instrument for Simultaneous, Compact, Sensitive, Rapid Measurement of NO2 and NOx

    NASA Astrophysics Data System (ADS)

    Wagner, N.; Fuchs, H.; Brown, S. S.; Dubé, W. P.; Lerner, B. M.; Williams, E. J.

    2008-12-01

    NO2 and NOx (=NO2+NO) measurements are essential for monitoring air-quality. Cavity ring- down spectroscopy (CRDS) is a highly sensitive technique to detect small concentrations of atmospheric trace gases such as NO2. Laser diode light sources enable the development of compact, lightweight instruments with minimal requirements for power and consumables. NO2 can be detected directly by absorption near 405 nm where ozone absorption and water absorption, which are the major concerns with respect to interferences, are small compared to that of NO2. Here, NOx is detected in a second cavity in addition to ambient NO2 by oxidation of ambient NO with excess ozone so that the sum of NO2 and NO is measured as NO2. This presentation will compare the performance of the CRDS instrument for NO and NO2 detection to standard instruments based on chemiluminescence for sensitivity, accuracy, linearity and dynamic range, and potential interferences using data from both laboratory and in-field comparisons.

  14. 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.

  15. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

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

    DOEpatents

    Holtom, Gary R.

    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.

  4. 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.

  5. 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.

  6. A compact diode laser cavity ring-down spectrometer for atmospheric measurements of NO3 and N2O5 with automated zeroing and calibration.

    PubMed

    Odame-Ankrah, Charles A; Osthoff, Hans D

    2011-11-01

    A compact rack-mounted cavity ring-down spectrometer (CRDS) for simultaneous measurements of the nocturnal nitrogen oxides NO(3) and N(2)O(5) in ambient air is described. The instrument uses a red diode laser to quantify mixing ratios of NO(3) (at its absorption maximum at 662 nm) and of N(2)O(5) following its thermal dissociation to NO(3) in a second detection channel. The spectrometer is equipped with an automated zeroing and calibration setup to determine effective NO(3) absorption cross-sections and NO(3) and N(2)O(5) inlet transmission efficiencies. The instrument response was calibrated using simultaneous measurements of NO(2), generated by thermal dissociation of N(2)O(5) and/or by titration of NO(3) with excess NO, using blue diode laser CRDS at 405 nm. When measuring ambient air, the (2σ, 10 s) precision of the red diode CRDS varied between 5 and 8 parts-per-trillion by volume (pptv), which sufficed to quantify N(2)O(5) concentrations under moderately polluted conditions. Sample N(2)O(5) measurements made on a rooftop on the University of Calgary campus in August 2010 are presented. A maximum N(2)O(5) mixing ratio of 130 pptv was observed, corresponding to a steady-state lifetime of less than 50 min. The NO(3) mixing ratios were below the detection limit, consistent with their predicted values based on equilibrium calculations. During the measurement period, the instrument response for N(2)O(5) was 70% of the theoretical maximum, rationalized by a slight mismatch of the laser diode output with the NO(3) absorption line and a N(2)O(5) inlet transmission efficiency less than unity. Advantages and limitations of the instrument's compact design are discussed.

  7. Diode laser-based cavity ring-down instrument for NO3, N2O5, NO, NO2 and O3 from aircraft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Dubé, W. P.; Washenfelder, R. A.; Young, C. J.; Pollack, I. B.; Ryerson, T. B.; Brown, S. S.

    2011-03-01

    This article presents a diode laser based, cavity ring-down spectrometer for simultaneous in situ measurements of four nitrogen oxide species, NO3, N2O5, NO, NO2, as well as O3, designed for deployment on aircraft. The instrument measures NO3 and NO2 by optical extinction at 662 nm and 405 nm, respectively; N2O5 is measured by thermal conversion to NO3, while NO and O3 are measured by chemical conversion to NO2. The instrument has several advantages over previous instruments developed by our group for measurement of NO2, NO3 and N2O5 alone, based on a pulsed Nd:YAG and dye laser. First, the use of continuous wave diode lasers reduces the requirements for power and weight and eliminates hazardous materials. Second, detection of NO2 at 405 nm is more sensitive than our previously reported 532 nm instrument, and does not have a measurable interference from O3. Third, the instrument includes chemical conversion of NO and O3 to NO2 to provide measurements of total NOx (= NO + NO2) and Ox (= NO2 + O3) on two separate channels; mixing ratios of NO and O3 are determined by subtraction of NO2. Finally, all five species are calibrated against a single standard based on 254 nm O3 absorption to provide high accuracy. Disadvantages include an increased sensitivity to water vapor on the 662 nm NO3 and N2O5 channels and a modest reduction in sensitivity for these species compared to the pulsed laser instrument. The measurement precision for both NO3 and N2O5 is below 1 pptv (2σ, 1 s) and for NO, NO2 and O3 is 170, 46, and 56 pptv (2σ, 1 s) respectively. The NO and NO2 measurements are less precise than research-grade chemiluminescence instruments. However, the combination of these five species in a single instrument, calibrated to a single analytical standard, provides a complete and accurate picture of nighttime nitrogen oxide chemistry. The instrument performance is demonstrated using data acquired during a recent field campaign in California.

  8. Diode laser-based cavity ring-down instrument for NO3, N2O5, NO, NO2 and O3 from aircraft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Dubé, W. P.; Washenfelder, R. A.; Young, C. J.; Pollack, I. B.; Ryerson, T. B.; Brown, S. S.

    2011-06-01

    This article presents a diode laser-based, cavity ring-down spectrometer for simultaneous in situ measurements of four nitrogen oxide species, NO3, N2O5, NO, NO2, as well as O3, designed for deployment on aircraft. The instrument measures NO3 and NO2 by optical extinction at 662 nm and 405 nm, respectively; N2O5 is measured by thermal conversion to NO3, while NO and O3 are measured by chemical conversion to NO2. The instrument has several advantages over previous instruments developed by our group for measurement of NO2, NO3 and N2O5 alone, based on a pulsed Nd:YAG and dye laser. First, the use of continuous wave diode lasers reduces the requirements for power and weight and eliminates hazardous materials. Second, detection of NO2 at 405 nm is more sensitive than our previously reported 532 nm instrument, and does not have a measurable interference from O3. Third, the instrument includes chemical conversion of NO and O3 to NO2 to provide measurements of total NOx (= NO + NO2) and Ox (= NO2 + O3) on two separate channels; mixing ratios of NO and O3 are determined by subtraction of NO2. Finally, all five species are calibrated against a single standard based on 254 nm O3 absorption to provide high accuracy. Disadvantages include an increased sensitivity to water vapor on the 662 nm NO3 and N2O5 channels and a modest reduction in sensitivity for these species compared to the pulsed laser instrument. The in-flight detection limit for both NO3 and N2O5 is 3 pptv (2 σ, 1 s) and for NO, NO2 and O3 is 140, 90, and 120 pptv (2 σ, 1 s) respectively. Demonstrated performance of the instrument in a laboratory/ground based environment is better by approximately a factor of 2-3. The NO and NO2 measurements are less precise than research-grade chemiluminescence instruments. However, the combination of these five species in a single instrument, calibrated to a single analytical standard, provides a complete and accurate picture of nighttime nitrogen oxide chemistry. The

  9. 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

  10. 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.

  11. Transcanalicular laser dacryocystorhinostomy using low energy 810 nm diode laser

    PubMed Central

    Gupta, Sanjiv K.; Kumar, Ajai; Agarwal, Swati; Pandey, Paritosh

    2012-01-01

    Background: Hypertrophic scarring may be a cause of failure after transcanalicular laser dacryocystorhinostomy (DCR) surgery. This hypertrophic scarring results from tissue charring and excessive coagulation, which may be caused by the high laser energy. We have evaluated the use of low energy settings to prevent hypertrophic scarring, for a successful outcome. Aims: To perform and evaluate transcanalicular laser DCR using low energy 810 nm diode laser. Design: Interventional, non-comparative, case series. Materials and Methods: Patients with nasolacrimal duct obstruction and chronic dacryocystitis, who needed DCR, and were fit for surgery under local anesthesia, were recruited to undergo transcanalicular laser DCR using a 810 nm diode laser. The outcome was measured by the patency of the lacrimal passage, as indicated by the relief in the symptoms and the patency on syringing at the last follow-up. The surgical time and surgical complications were noted. Statistical Analysis Used: Descriptive analysis. Results: The study included 94 patients. The average age was 30.1 years (range 15 - 69 years). Seventy (74.4%) patients were female. Eight patients had failed external DCR. Per-operative patency of the passage was obtained in all the patients. Average surgical time was seven minutes (5 – 18 minutes). At the end of the study period of one year, a successful outcome was seen in 85 patients (90.5%). There were eight patients of previous failed DCR surgeries, and six of them achieved a cure at the end of follow-up. Conclusions: Transcanalicular Laser DCR can be safely performed using a low power 810 nm diode laser. The surgery is elegant, minimally invasive, allows fast rehabilitation, and has an excellent success rate. PMID:23439888

  12. Differential sensitivity of osteoblasts and bacterial pathogens to 405-nm light highlighting potential for decontamination applications in orthopedic surgery

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Praveen; Maclean, Michelle; MacGregor, Scott J.; Anderson, John G.; Grant, M. Helen

    2014-10-01

    Healthcare associated infections pose a major threat to patients admitted to hospitals and infection rates following orthopedic arthroplasty surgery are as high as 4%. A 405-nm high-intensity narrow spectrum light has been proven to reduce environmental contamination in hospital isolation rooms, and there is potential to develop this technology for application in arthroplasty surgery. Cultured rat osteoblasts were exposed to varying light intensities and it was found that exposures of up to a dose of 36 J/cm2 had no significant effect on cell viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay], function (alkaline phosphatase activity), and proliferation rate (BrdU cell proliferation assay). High irradiance exposures (54 J/cm2) significantly affected the cell viability indicating that the effects of 405-nm light on osteoblasts are dose dependent. Additionally, exposure of a variety of clinically related bacteria to a dose of 36 J/cm2 resulted in up to 100% kill. These results demonstrating the differential sensitivity of osteoblasts and bacteria to 405-nm light are an essential step toward developing the technique for decontamination in orthopedic surgery.

  13. 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

  14. 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.

  15. Method for partially coating laser diode facets

    NASA Technical Reports Server (NTRS)

    Dholakia, Anil R. (Inventor)

    1990-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Advances in bonding technology for high power diode laser bars

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Li, Xiaoning; Hou, Dong; Feng, Feifei; Liu, Yalong; Liu, Xingsheng

    2015-02-01

    Due to their high electrical-optical conversion efficiency, compact size and long lifetime, high power diode lasers have found increased applications in many fields. As the improvement of device technology, high power diode laser bars with output power of tens or hundreds watts have been commercially available. With the increase of high current and output power, the reliability and lifetime of high power diode laser bars becomes a challenge, especially under harsh working conditions and hard-pulse operations. The bonding technology is still one of the bottlenecks of the advancement of high power diode laser bars. Currently, materials used in bonding high power diode laser bars are commonly indium and goldtin solders. Experimental and field application results indicates that the lifetime and reliability of high power diode laser bars bonded by gold-tin solder is much better than that bonded by indium solder which is prone to thermal fatigue, electro-migration and oxidization. In this paper, we review the bonding technologies for high power diode laser bars and present the advances in bonding technology for single bars, horizontal bar arrays and vertical bar stacks. We will also present the challenges and issues in bonding technology for high power diode laser bars and discuss some approaches and strategies in addressing the challenges and issues.

  1. 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.

  2. Position and mode dependent coupling of terahertz quantum cascade laser fields to an integrated diode

    NASA Astrophysics Data System (ADS)

    Dyer, Gregory C.; Nordquist, Christopher D.; Cich, Michael J.; Ribaudo, Troy; Grine, Albert D.; Fuller, Charles T.; Reno, John L.; Wanke, Michael C.

    2013-10-01

    A Schottky diode integrated into a terahertz quantum cascade laser waveguide couples directly to the internal laser fields. In a multimode laser, the diode response is correlated with both the instantaneous power and the coupling strength to the diode of each lasing mode. Measurements of the rectified response of diodes integrated in two quantum cascade laser cavities at different locations indicate that the relative diode position strongly influences the laser-diode coupling.

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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.

  8. 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.

  9. Semiconductor defect metrology using laser-based quantitative phase imaging

    NASA Astrophysics Data System (ADS)

    Zhou, Renjie; Edwards, Chris; Popescu, Gabriel; Goddard, Lynford

    2015-03-01

    A highly sensitive laser-based quantitative phase imaging tool, using an epi-illumination diffraction phase microscope, has been developed for silicon wafer defect inspection. The first system used a 532 nm solid-state laser and detected 20 nm by 100 nm by 110 nm defects in a 22 nm node patterned silicon wafer. The second system, using a 405 nm diode laser, is more sensitive and has enabled detection of 15 nm by 90 nm by 35 nm defects in a 9 nm node densely patterned silicon wafer. In addition to imaging, wafer scanning and image-post processing are also crucial for defect detection.

  10. 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

  11. 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.

  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. 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.

  14. 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. PMID:27370428

  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. 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.

  17. 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.

  18. 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)

  19. Frequency-doubled monolithic master oscillator power amplifier laser diode

    SciTech Connect

    Waarts, R.; Sanders, S.; Parke, R.; Mehuys, D.; Lang, R.; O'Brien, S.; Dzurko, K.; Welch, D.; Scifres, D. )

    1993-10-01

    Single-pass frequency doubling of laser diodes extends the wavelength range of infrared laser diodes to blue-green wavelengths. The authors describe the first experiments of frequency doubling of a coherent, high-power, monolithic master oscillator power amplifier (M-MOPA) laser diode. The output from a 1-W M-MOPA is frequency doubled in a single pass through an 8.2-mm-long KNbO[sub 3] crystal. They obtained 3.7-mW diffraction-limited output power at a wavelength of 491 nm and demonstrated modulation at 20 MHz.

  20. Laser diode arrays for expanded mine detection capability

    NASA Astrophysics Data System (ADS)

    Crosby, Frank J.; Holloway, John H., Jr.; Petee, Danny A.; Stetson, Suzanne P.; Suiter, Harold R.; Tinsley, Ken R.

    2002-08-01

    A tactical unmanned aerial vehicle-size illumination system for enhanced mine detection capabilities has been designed, developed, integrated, and tested at the Coastal Systems Station. Airborne test flights were performed from June 12, 2001 to February 1, 2002. The Airborne Laser Diode Array Illuminator uses a single-wavelength compact laser diode array stack to provide illumination and is coupled with a pair of intensified CCD video cameras. The cameras were outfitted with various lenses and polarization filters to determine the benefits of each of the configurations. The first airborne demonstration of a laser diode illumination system is described and its effectiveness to perform nighttime mine detection operations is shown.

  1. The recording and processing of pulsed laser diode spectra

    NASA Technical Reports Server (NTRS)

    Fuhr, Peter L.; Maufer, Thomas A.

    1987-01-01

    A system capable of measuring and statistically analyzing wavelength and intensity fluctuations in pulsed laser diode output beams has been developed. The snapshot wavelength-intensity performance of laser diodes emitting discrete short-duration optical pulse is determined by isolating and recording individual pulses. Statistical processing of the resultant data generates information about the magnitude and/or frequency of occurrence of power variations or wavelength fluctuations in narrow optical bands. The system configuration along with plots depicting results based on measurements taken for various laser diodes are presented.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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. PMID:24977887

  9. High-brightness fiber-coupled diode laser module

    NASA Astrophysics Data System (ADS)

    Dorsch, Friedhelm; Hennig, Petra; Nickel, Michael

    1998-05-01

    Based on a pair of step-mirrors for beam rearranging we coupled the emission of three high-power diode laser arrays into an optical fiber of 800 micrometer diameter. We compressed the fast axis collimated beams of three diode lasers in respect to their fast axes by means of a step prism and symmetrized the beam parameter product by reordering the radiation which is focused into a fiber then. By simple optimization a coupling efficiency of 70% can be obtained.

  10. 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.

  11. Low-Loss Coupler For Microwave Laser-Diode Modulation

    NASA Technical Reports Server (NTRS)

    Toda, Minoru

    1991-01-01

    Elimination of series resistor reduces loss of radio-frequency power. Quarter-wavelength matching section connected to transmission line eliminates need for resistor near laser diode and extends frequency response of system. Concept significantly extends relatively flat frequency response of laser diode or similar component, while simplifying design of its package, increasing amplitude of output signal, and reducing dissipation of heat by eliminating resistance. Phase characteristics approximately linear and any digital information transmitted not significantly altered.

  12. 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.

  13. 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.

  14. Investigation of communication laser diodes for the SILEX project

    NASA Astrophysics Data System (ADS)

    Menke, Bodo; Loeffler, Roland

    1989-10-01

    The Semiconductor Intersatellite Laser Experiment (SILEX) will construct an optical communications link over a range of 45,000 km, using 0.8-micron AlGaAs laser diodes capable of transmitting 65 Mbit/s. Numerous single-stripe diode types were furnished by manufacturers and subjected to measurements to establish conformity with the required far-field pattern spectrum spread under QPPM-modulation, mode-hopping, astigmatism, and rms wavefront error (WFE); WFE is demonstrated to be strongly affected by the laser window's introduction of strong spherical aberration. Three laser types have been chosen for breadboarding and accelerated life tests.

  15. Combless broadband terahertz generation with conventional laser diodes.

    PubMed

    Molter, D; Wagner, A; Weber, S; Jonuscheit, J; Beigang, R

    2011-03-14

    We present a novel technique to generate a continuous, combless broadband Terahertz spectrum with conventional low-cost laser diodes. A standard time-domain spectroscopy system using photoconductive antennas is pumped by the output of two tunable diode lasers. Using fine tuning for one laser and fine and coarse tuning for the second laser, difference frequency generation results in a continuous broadband THz spectrum. Fast coarse-tuning is achieved by a simple spatial light modulator introduced in an external cavity. The results are compared to multi-mode operation for THz generation. PMID:21445166

  16. Combless broadband terahertz generation with conventional laser diodes.

    PubMed

    Molter, D; Wagner, A; Weber, S; Jonuscheit, J; Beigang, R

    2011-03-14

    We present a novel technique to generate a continuous, combless broadband Terahertz spectrum with conventional low-cost laser diodes. A standard time-domain spectroscopy system using photoconductive antennas is pumped by the output of two tunable diode lasers. Using fine tuning for one laser and fine and coarse tuning for the second laser, difference frequency generation results in a continuous broadband THz spectrum. Fast coarse-tuning is achieved by a simple spatial light modulator introduced in an external cavity. The results are compared to multi-mode operation for THz generation.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. VBG controlled narrow bandwidth diode laser arrays

    NASA Astrophysics Data System (ADS)

    Levy, Joseph; Feeler, Ryan; Junghans, Jeremy

    2012-03-01

    Northrop Grumman Cutting Edge Optronics has developed large kilowatt class lensed laser diode arrays with subnanometer spectral width using Volume Bragg Grating (VBG) reflectors. Using these CW arrays with 100W bars at 885nm, excellent absorption in Nd:YAG is achieved, with lower thermal aberration than can be attained with 808nm pumps. The additional cost of the VBG reflectors and their alignment is partially offset by the much broader wavelength tolerance that is allowed in the unlocked array enhancing bar yield. Furthermore, the center wavelength of the arrays exhibit lower temperature sensitivity allowing the arrays to be operated over a wider current or temperature range than arrays without wavelength control. While there is an efficiency penalty associated with the addition of VBGs of 5-8%, it is more than compensated for by enhanced absorption, especially when used with narrowband absorption lines, such as 885nm in Nd:YAG. An overview of the design and manufacturing issues for arrays that are wavelength-locked with VBGs is presented along with the effect of post-construction hard UV exposure.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Self-Collimating Unstable-Resonator Diode Lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1992-01-01

    Proposed unstable-resonator diode lasers produce solid, collimated output beams without external collimating optics. Simpler to construct, used as pumps for optical-fiber amplifiers in telecommunications, for other solid-state lasers, and sources of light for free-space communications.

  8. 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.

  9. 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.

  10. 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.

  11. High-brightness diode lasers with very narrow vertical divergence

    NASA Astrophysics Data System (ADS)

    Erbert, Götz; Bugge, Frank; Eppich, Bernd; Fricke, Joerg; Hasler, Karl-Heinz; Paschke, Katrin; Pietrzak, Agnieszka; Wenzel, Hans; Tränkle, Günther

    2008-02-01

    A narrow vertical divergence of about 30° including 95% of power is highly desired in many applications. Principal designs for narrow divergence diode lasers like simple broad waveguide and more sophisticated resonant waveguide structures are discussed. Devices with narrow divergence could be realized in the wavelength range 800nm to 1060nm using very broad waveguide structures. More than 1W in fundamental mode and about 5W nearly diffraction limited output could be achieved from ridge waveguide laser and from diode lasers with tapered resonator structure, respectively.

  12. 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.

  13. 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.

  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. Thermal Regime of High-power Laser Diodes

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Krokhin, O. N.; Oleshchenko, V. A.; Pevtsov, V. F.; Popov, Yu. M.; Cheshev, E. A.

    We discuss the design and application perspectives of different crystal, ceramic and composite-type submounts with thermo-compensating properties as well as submounts from materials with high thermal conductivity for overcoming thermal problem in high-power laser diodes (LD) and improving thermal management of other high-power optoelectronic and electronic semiconductor devices. Thermal fields in high-power laser diodes were calculated in 3 D thermal model at CW operation for some heatsink designs taking into account the experimental dependence of laser total efficiency against pumping current in order to extend the range of reliable operation up to thermal loads 20-30 W and corresponding output optical power up to 15-20 W for 100 μm stripe laser diodes.

  16. Despeckling fly's eye homogenizer for single mode laser diodes.

    PubMed

    Mizuyama, Yosuke; Harrison, Nathan; Leto, Riccardo

    2013-04-01

    A novel fly's eye homogenizer for single mode laser diodes is presented. This technology overcomes the speckle problem that has been unavoidable for fly's eye homogenizers used with coherent light sources such as single mode laser diodes. Temporal and spatial coherence are reduced simultaneously by introducing short pulse driving of the injection current and a staircase element. Speckle has been dramatically reduced to 5% from 87% compared to a conventional system and a uniform laser line illumination was obtained by the proposed fly's eye homogenizer with a single mode UV-blue laser diode for the first time. A new spatial coherence function was mathematically formulated to model the proposed system and was applied to a partially coherent intensity formula that was newly developed in this study from Wolf's theory to account for the results. PMID:23571997

  17. 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.

  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. Construction of an Extended Cavity Tunable Diode Laser

    NASA Astrophysics Data System (ADS)

    Deveney, Edward; Metcalf, Harold; Noe, John

    2001-03-01

    A diverse and vast amount of experiments at the forefront of experimental physics typically use diode lasers as an integral part of their arrangement. However, researchers who use unmodified commercially available diode lasers run into several complications. The laser diode that is purchased is often not of the same wavelength as is advertised; thus the researcher’s desired wavelength is not met. Because the semiconductor has such a short external cavity, it is very sensitive to the injection current, changes in room temperature, and has a large linewidth making it harder to tune. To obtain a finely tuned diode laser, temperature and current controlling of the diode laser are used in conjunction with an extended semiconductor cavity. This is achieved by mounting the hermetically sealed assembly atop a thermoelectric cooler, which uses the Peltier effect. Furthermore, the variation of the injection current may be used as an additional control for the wavelength output of the diode. The power range of 70 mW as controlled by the injection current adjusts the wavelength by a span of only 4 nanometers. The extended cavity consists of a diffraction grating adhered to a mirror mount and is used for grating feedback. That in turn is used to reduce the linewidth sufficiently enough in order to provide much better tunability. In the next three weeks, the tunable diode laser will be specifically applied to research in the areas of Second Harmonic Generation in a PPLN Crystal and Saturated Rubidium Spectroscopy. This study was supported in part by NSF grant PHY99-12312.

  20. Brilliant high-power diode lasers based on broad area lasers

    NASA Astrophysics Data System (ADS)

    Krause, V.; Koesters, A.; Koenig, H.; Strauss, U.

    2008-02-01

    Within the German national research project "Briolas" Osram Semiconductors and Laserline GmbH cooperated in the subproject "Brilasi" which focused mainly on Brilliant Laser Diodes for Industrial Applications. The project was finished in December 2007 and lasted more than three years. Laserline and Osram are investigating the performance of broad area diode lasers with a bar width from 1.0 to 10.0 mm in high brilliance diode laser beam sources. Within the program different fibre coupled laser sources are built up: 1. Fibre coupled diode laser beam source with a Beam Parameter Product (BBP) of 40 mmxmrad built from diode laser bars with 10 mm bar width. 2. Fibre coupled diode laser beam source with a BBP of 20 mmxmrad built from Mini-Bars with a bar width of 3.0 mm and 8 emitters. These Different solutions are characterized regarding the electro optical performance. The laser output characteristics are determined for the diode laser device as well as the complete beam source. Lifetime tests are conducted to determine the long term stability of the prototypes and the different chip material.

  1. Qualification of diode foil materials for excimer lasers

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Shurter, R. P.; Rose, E. A.

    The Aurora facility at Los Alamos National Laboratory uses KrF excimer lasers to produce 248 nm light for inertial confinement fusion applications. Diodes in each amplifier produce relativistic electron beams to pump a Kr-F-Ar gas mixture. A foil is necessary to separate the vacuum diode from the laser gas. High tensile strength, high electron transmission, low ultraviolet reflectivity, and chemical compatibility with fluorine have been identified as requisite foil properties. Several different materials were acquired and tested for use as diode foils. Transmission and fluorine compatibility tests were performed using the Electron Gun Test Facility (EGTF) at Los Alamos. Off-line tests of tensile strength and reflectivity were performed. Titanium foil, which is commonly used as a diode foil, was found to generate solid and gaseous fluoride compounds, some of which are highly reactive in contact with water vapor.

  2. Diode pumped alkali vapor lasers for high power applications

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.; Komashko, A.

    2008-02-01

    General Atomics has been engaged in the development of diode pumped alkali vapor lasers. We have been examining the design space looking for designs that are both efficient and easily scalable to high powers. Computationally, we have looked at the effect of pump bandwidth on laser performance. We have also looked at different lasing species. We have used an alexandrite laser to study the relative merits of different designs. We report on the results of our experimental and computational studies.

  3. Optical power supply unit utilizing high power laser diode module developed for fiber laser pumping

    NASA Astrophysics Data System (ADS)

    Sakamoto, Akira; Kiyoyama, Wataru; Yamauchi, Ryozo

    2014-05-01

    High power laser diode developed for fiber laser pumping is evaluated as a light source for an optical power supply unit. The output power of the newly developed laser diode module exceeds 15 W with 105 μm core fiber. It is estimated that more than 1600 mW power supply can be achieved with the single emitter laser diode module and a polycrystalline silicon cell over 1 km away from the light source. This unit can be used for sensor nodes in the fiber sensor network.

  4. Thermal compensator for closed-cycle helium refrigerator. [assuring constant temperature for an infrared laser diode

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.; Hillman, J. J. (Inventor)

    1979-01-01

    The wave length of an infrared, semiconductor laser diode having an output frequency that is dependent on the diode temperature is maintained substantially constant by maintaining the diode temperature constant. The diode is carried by a cold tip of a closed cycle helium refrigerator. The refrigerator has a tendency to cause the temperature of the cold tip to oscillate. A heater diode and a sensor diode are placed on a thermal heat sink that is the only highly conductive thermal path between the laser diode and the cold tip. The heat sink has a small volume and low thermal capacitance so that the sensing diode is at substantially the same temperature as the heater diode and substantially no thermal lag exists between them. The sensor diode is connected in a negative feedback circuit with the heater diode so that the tendency of the laser diode to thermally oscillate is virtually eliminated.

  5. Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  6. Experimental study of the diode pumped alkali laser (DPAL)

    NASA Astrophysics Data System (ADS)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio

    2014-02-01

    A small-scale cesium diode-pumped alkali laser (DPAL) apparatus has been developed for fundamental researches. A commercial laser diode with volume Bragg grating outcoupler is used to pump the gain cell longitudinally. Both windows of the gain cell are set at Brewster's angle for minimum loss and maximum durability. Output coupling coefficient is continuously variable from 13% to 85% by the slanted quartz plate outcoupler inserted in the optical resonator. Small signal gain is measured with a laser diode probe at various gain cell temperatures. A 6.5 W continuouswave output with 56% optical-to-optical conversion efficiency (based on the absorbed power) has been achieved. A numerical simulation code is developed and its calculation results are in good agreement with the experiments.

  7. Materials processing with a high power diode laser

    SciTech Connect

    Li, L.; Lawrence, J.; Spencer, J.T.

    1996-12-31

    This paper reports on work exploring the feasibility of a range of materials processing applications using a Diomed 60W diode laser delivered through a 600{mu}m diameter optical fibre to a 3 axis CNC workstation. The applications studied include: marking/engraving natural stones (marble and granite), marking ceramic tiles, sealing tile grouts, cutting and marking glass, marking/engraving wood, stripping paint and lacquer, and welding metallic wires. The study shows that even at the present limited power level of diode lasers, many materials processing applications can be accomplished with satisfactory results. Through the study an initial understanding of interaction of high power diode laser (HPDL) beam with various materials has been gained. Also, within the paper basic beam characteristics, and current R&D activities in HPDL technology and materials processing applications are reviewed.

  8. 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. PMID:8175359

  9. 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.

  10. 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.

  11. Overview on new diode lasers for defense applications

    NASA Astrophysics Data System (ADS)

    Neukum, Joerg

    2012-11-01

    Diode lasers have a broad wavelength range, from the visible to beyond 2.2μm. This allows for various applications in the defense sector, ranging from classic pumping of DPSSL in range finders or target designators, up to pumping directed energy weapons in the 50+ kW range. Also direct diode applications for illumination above 1.55μm, or direct IR countermeasures are of interest. Here an overview is given on some new wavelengths and applications which are recently under discussion. In this overview the following aspects are reviewed: • High Power CW pumps at 808 / 880 / 940nm • Pumps for DPAL - Diode Pumped Alkali Lasers • High Power Diode Lasers in the range < 1.0 μm • Scalable Mini-Bar concept for high brightness fiber coupled modules • The Light Weight Fiber Coupled module based on the Mini-Bar concept Overall, High Power Diode Lasers offer many ways to be used in new applications in the defense market.

  12. Multiwavelength erbium fiber ring laser using Sagnac loop and Fabry-Perot laser diode

    NASA Astrophysics Data System (ADS)

    Yeh, C.-H.; Shih, F.-Y.; Chen, C.-T.; Lee, C.-N.; Chi, S.

    2008-03-01

    We propose and demonstrate experimentally a simply multiple-wavelength erbium compound ring fiber laser employing a Sagnac interferometer with erbium-doped fiber amplifier (EDFA) and Fabry-Perot laser diode (FP-LD). The proposed laser has the advantage of simply structure and easy fabrication, lower insertion loss and cost-effective. Based on the Sagnac fiber laser scheme, the proposed laser can lase eight wavelengths simultaneously. Moreover, the optical output stability of the ring laser has been also discussed.

  13. Application of NIR laser diodes to pulse oximetry

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    A transmittance pulse oximeter based on near-infrared laser diodes for monitoring arterial blood hemoglobin oxygen saturation has been developed and tested. The measurement system consists of the optical sensor, sensor electronics, acquisition board and personal computer. The system has been tested in a two-part experimental study involving human volunteers. A calibration curve was derived and healthy volunteers were monitored under normal and apnea conditions, both with the proposed system and with a commercial pulse oximeter. The obtained results demonstrate the feasibility of using a sensor with laser diodes emitting at specific near-infrared wavelengths for pulse oximetry.

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

    PubMed Central

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

    2015-01-01

    Beautification of smiles is becoming an everyday requirement in dental practice. Apart from teeth, gingiva also plays an important role in smile esthetics. Excessive visualization of gingiva is a common complaint among patients seeking esthetic treatment. A wide variety of procedures are available for correction of excessive gum display based on the cause of the condition. Soft tissue diode laser contouring of gingiva is a common procedure that can be undertaken in a routine dental setting with excellent patient satisfaction and minimal post-operative sequale. Two cases of esthetic crown lengthening with diode laser 810 nm are presented here. PMID:26668491

  15. A portable lidar using a diode-pumped YAG laser

    NASA Technical Reports Server (NTRS)

    Takeuchi, N.; Okumura, H.; Sugita, T.; Matsumoto, H.; Yamaguchi, S.

    1992-01-01

    A Mie lidar system is technically established and is used for monitoring air pollution, stratospheric and boundary layer aerosol distribution, plume dispersion, visibility, and the study of atmospheric structure and cloud physics. However, a lidar system is not widely used because of its cumbersome handling and unwieldy portability. Although the author developed a laser diode lidar system based on RM-CW technique, it has a limit of measurement distance. Here we report the development of an all solid Mie lidar system using a diode-pumped Nd:YAG laser and a Si-APD detector. This was constructed as a prototype of a handy lidar system.

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

    PubMed

    Xu, Qiang; Han, Yiping; Cui, Zhiwei

    2010-01-20

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

  17. Contact diode laser: high power application through fiberoptic cutting tips.

    PubMed

    Wafapoor, H; Peyman, G A; Moritera, T

    1994-01-01

    Diode laser energy has been applied through a fiberoptic probe using a power setting of 2.5 watts (W) in the continuous mode. In this study we employed high-power diode laser energy (4 to 12 W, continuous wave) to incise ocular tissue through a fiberoptic probe using 100 microns and 300 microns tips. The retina was photocoagulated with a 300 microns orb tip. No bleeding occurred at the incision sites. Histologic evaluation revealed coagulation into the healthy tissue ranging from 10 to 50 microns.

  18. Broadband laser diode emitting at 1. 28. mu. m wavelength

    SciTech Connect

    Takada, K.; Noda, J.

    1985-10-15

    This letter presents a broadband laser diode (LD) emitting at the 1.28 ..mu..m wavelength fabricated by introducing an absorption region (300 ..mu..m long) into a conventional 600-..mu..m-long InGaAsP laser diode. The LD operates by the pulsed modulation of a high peak current whose repetition rate and duty cycle are respectively 200 kHz and 5%. The typical output power and the spectral width of the LD are 3.8 mW and 58 A, and the measured coherence length is 210 ..mu..m.

  19. Rectified diode response of a multimode quantum cascade laser integrated terahertz transceiver.

    PubMed

    Dyer, Gregory C; Norquist, Christopher D; Cich, Michael J; Grine, Albert D; Fuller, Charles T; Reno, John L; Wanke, Michael C

    2013-02-25

    We characterized the DC transport response of a diode embedded in a THz quantum cascade laser as the laser current was changed. The overall response is described by parallel contributions from the rectification of the laser field due to the non-linearity of the diode I-V and from thermally activated transport. Sudden jumps in the diode response when the laser changes from single mode to multi-mode operation, with no corresponding jumps in output power, suggest that the coupling between the diode and laser field depends on the spatial distribution of internal fields. The results demonstrate conclusively that the internal laser field couples directly to the integrated diode.

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

    NASA Astrophysics Data System (ADS)

    Bergh, Arpad A.

    2004-09-01

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

  1. 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.

  2. 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%.

  3. Method and system for homogenizing diode laser pump arrays

    DOEpatents

    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%.

  4. Discretely tunable single-frequency fibre Bragg grating diode laser

    SciTech Connect

    Duraev, V P; Lutts, G B; Nedelin, E T; Sumarokov, M A; Medvedkov, O I; Vasil'ev, S A

    2007-12-31

    The results of the development of discretely tunable single-frequency semiconductor lasers with the external cavity based on fibre Bragg gratings (FBGs) written in a single-mode fibre are presented. It is shown, in particular, that, by using an external cavity semiconductor laser with the output mirror representing a superposition of several FBGs with different resonance wavelengths, it is possible to obtain lasing at one or several wavelengths simultaneously by varying the injection current and (or) the temperature of the active area of the laser diode. (lasers)

  5. Piezo-locking a diode laser with saturated absorption spectroscopy

    SciTech Connect

    Debs, J. E.; Robins, N. P.; Lance, A.; Kruger, M. B.; Close, J. D

    2008-10-01

    We demonstrate modulation-based frequency locking of an external cavity diode laser, utilizing a piezo-electrically actuated mirror, external to the laser cavity, to create an error signal from saturated absorption spectroscopy. With this method, a laser stabilized to a rubidium hyperfine transition has a FWHM of 130 kHz over seconds, making the locked laser suitable for experiments in atomic physics, such as creating and manipulating Bose-Einstein condensates. This technique combines the advantages of low-amplitude modulation, simplicity, performance, and price, factors that are usually considered to be mutually exclusive.

  6. 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.

  7. Inner retinal damage after exposure to green diode laser during a laser show

    PubMed Central

    Jeon, Sohee; Lee, Won Ki

    2014-01-01

    Here we report two cases of retinal damage after exposure to a 510 nm laser diode during a laser show. The first patient was a 20-year-old female who presented with decreased visual acuity in her right eye after visiting a dance party with a diode laser show (wavelength 510 nm, power 2 mW), although she did not directly see the light. Retinal examination revealed a sub-internal limiting membrane hemorrhage and a small laser burn. The second patient was a 20-year-old female who visited for decreased vision in her left eye. She described similar events as the first patient. An exposure to green diode laser can result in retinal damage. It is strongly recommended that certified personnel operate laser devices used in indoor laser shows under strict regulation. PMID:25506208

  8. High brightness diode-pumped organic solid-state laser

    SciTech Connect

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-02-02

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  9. High brightness diode-pumped organic solid-state laser

    NASA Astrophysics Data System (ADS)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-02-01

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  10. 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.

  11. Polarization/Spatial Combining of Laser-Diode Pump Beams

    NASA Technical Reports Server (NTRS)

    Gelsinger, Paul; Liu, Duncan

    2008-01-01

    A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

  12. Monolithic laser diode structure for microwave generation

    SciTech Connect

    Goldberg, L.; Weller, J.F.

    1990-03-06

    This patent describes an apparatus. It comprises: a semiconductor substrate; a semiconductor master laser and first and second semiconductor slave lasers fabricated adjacent to each other on the semiconductor substrate. The master laser generating an optical output at a frequency f{sub 0} and sidebands at multiples of {Delta}f, the first and second slave lasers being tuned to approximately coincide with first and second preselected sidebands of the master laser; and means for respectively injection-locking the first and second slave lasers to the first and second preselected sidebands.

  13. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

    Schneider, Richard P.; Lott, James A.

    1994-01-01

    Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors.

  14. Fiber Coupled Laser Diodes with Even Illumination Pattern

    NASA Technical Reports Server (NTRS)

    Howard, Richard T. (Inventor)

    2007-01-01

    An optical fiber for evenly illuminating a target. The optical fiber is coupled to a laser emitting diode and receives laser light. The la ser light travels through the fiber optic and exits at an exit end. T he exit end has a diffractive optical pattern formed thereon via etch ing, molding or cutting, to reduce the Gaussian profile present in co nventional fiber optic cables The reduction of the Gaussian provides an even illumination from the fiber optic cable.

  15. Even Illumination from Fiber-Optic-Coupled Laser Diodes

    NASA Technical Reports Server (NTRS)

    Howard, Richard T.

    2006-01-01

    A method of equipping fiber-optic-coupled laser diodes to evenly illuminate specified fields of view has been proposed. The essence of the method is to shape the tips of the optical fibers into suitably designed diffractive optical elements. One of the main benefits afforded by the method would be more nearly complete utilization of the available light. Diffractive optics is a relatively new field of optics in which laser beams are shaped by use of diffraction instead of refraction.

  16. Unstable-Resonator Oscillator/Amplifier Diode Laser

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.; Mittelstein, Michael; Tiberio, Richard C.; Forouhar, Siamak; Crawford, Deborah

    1994-01-01

    Fabricated as single-chip integrated circuit. Device based partly on concept proved in commercial solid-state lasers: using unstable-resonator oscillator to define electromagnetic mode and, following oscillator, traveling-wave amplifier to generate high power. Mode-definition and power-amplification functions optimized separately. Hyperbolic-grating, unstable-resonator oscillator/amplifier diode laser produces single-longitudinal-mode, broad, laterally coherent, diffraction-limited, high-power beam.

  17. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

    Schneider, R.P.; Lott, J.A.

    1994-09-27

    Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

  18. Investigation of the light field of a semiconductor diode laser.

    PubMed

    Ankudinov, A V; Yanul, M L; Slipchenko, S O; Shelaev, A V; Dorozhkin, P S; Podoskin, A A; Tarasov, I S

    2014-10-20

    Scanning near-field optical microscopy was applied to study, with sub-wavelength spatial resolution, the near- and the far-field distributions of propagating modes from a high-power laser diode. Simple modeling was also performed and compared with experimental results. The simulated distributions were consistent with the experiment and permitted clarification of the configuration of the transverse modes of the laser. PMID:25401675

  19. Contact diode laser application through a fiberoptic cutting tip.

    PubMed

    Peyman, G A; Cruz, S A; Ruiz-Lapuente, C

    1991-01-01

    We applied diode laser energy through a fiberoptic probe to cut ocular structures. The diameter of the probe's tip was 100 microns. The amount of energy used for cutting the lid, the cornea, or for perforation of the glove was 2.5 watts in the continuous mode. The incised border demonstrated coagulation into the healthy tissue ranging from 10 to 50 microns.

  20. Optical feedback effects upon laser diode oscillation field spectrum

    SciTech Connect

    Favre, F.; LeGuen, D.; Simon, J.

    1982-10-01

    Optical feedback effects on spectral properties of a semi-conductor laser diode coupled to a single-mode fiber cavity are investigated. Linewidth reduction from 6 MHz to less than 30 kHz and freququency stability improvement with increasing feedback are reported. Experiments are in good agreement with theory for short fiber cavities.

  1. 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.

  2. 946 nm Diode Pumped Laser Produces 100mJ

    NASA Technical Reports Server (NTRS)

    Axenson, Theresa J.; Barnes, Norman P.; Reichle, Donald J., Jr.

    2000-01-01

    An innovative approach to obtaining high energy at 946 nm has yielded 101 mJ of laser energy with an optical-to-optical slope efficiency of 24.5%. A single gain module resonator was evaluated, yielding a maximum output energy of 50 mJ. In order to obtain higher energy a second gain module was incorporated into the resonator. This innovative approach produced un-surprised output energy of 101 mJ. This is of utmost importance since it demonstrates that the laser output energy scales directly with the number of gain modules. Therefore, higher energies can be realized by simply increasing the number of gain modules within the laser oscillator. The laser resonator incorporates two gain modules into a folded "M-shaped" resonator, allowing a quadruple pass gain within each rod. Each of these modules consists of a diode (stack of 30 microlensed 100 Watt diode array bars, each with its own fiber lens) end-pumping a Nd:YAG laser rod. The diode output is collected by a lens duct, which focuses the energy into a 2 mm diameter flat to flat octagonal pump area of the laser crystal. Special coatings have been developed to mitigate energy storage problems, including parasitic lasing and amplified spontaneous emission (ASE), and encourage the resonator to operate at the lower gain transition at 946 nm.

  3. 980-nm diode laser application in electroneurophysiology: a LEP study

    NASA Astrophysics Data System (ADS)

    Guelsoy, Murat; Durak, Kadir; Kurt, Adnan; Karamursel, Sacit; Cilesiz, Inci F.

    2001-01-01

    The aim of the present study was to test the feasibility of the 980 nm diode laser for LEP (Laser Evoked Potentials) studies. Human subjects were exposed to laser stimulation. After the pain thresholds of the subjects were determined with respect to laser power level, 1.5 times the threshold value was applied and laser evoked potentials were recorded using standard EEG techniques. LEPs were obtained due to right hand stimulation. Latency and amplitude values of LEPs were found in accordance with those reported in the literature. Statistical evaluation showed differences in the LEPs at C3 and C4 locations as a function of the sex of the subjects. The power levels used in the present study was three times less than the levels applied for Nd: YAG laser in the literature. The evoked potential parameters measured were in consistence with the data reported by earlier researchers. Moreover, it was found that, LEPs due to 980 nm wavelength irradiation can be recorded by applying less energy when compared to Nd:YAG laser. This result indicated the potential of diode laser for LEP studies.

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

    NASA Astrophysics Data System (ADS)

    Denisenkov, Valentin S.; Kiyko, Vadim V.; Vdovin, Gleb V.

    2015-03-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface heating with different approaches to make the heat distribution more uniform and the process more efficient. High-power lasers can in theory provide in-bulk heating which can sufficiently increase the uniformity of heat distribution thus making the process more efficient. We chose two media (vegetable fat and glucose) for feasibility experiments. First, we checked if the media have necessary absorption coefficients on the wavelengths of commercially available laser diodes (940-980 nm). This was done using spectrophotometer at 700-1100 nm which provided the dependences of transmission from the wavelength. The results indicate that vegetable fat has noticeable transmission dip around 925 nm and glucose has sufficient dip at 990 nm. Then, after the feasibility check, we did numerical simulation of the heat distribution in bulk using finite elements method. Based on the results, optimal laser wavelength and illuminator configuration were selected. Finally, we carried out several pilot experiments with high-power diodes heating the chosen media.

  5. Newly developed high-power laser diode bars

    NASA Astrophysics Data System (ADS)

    Kageyama, Nobuto; Morita, Takenori; Torii, Kousuke; Takauji, Motoki; Nagakura, Takehito; Maeda, Junya; Miyajima, Hirofumi; Yoshida, Harumasa

    2012-03-01

    High Power Laser Diode (LD) modules are widely used as high-brightness light sources for pumping solid-state lasers and for direct diode laser processing utilizing a compact feature. The LD bars installed in modules are required with higher output power, efficiency and beam quality. We have optimized the LD bar structure for high output power and efficient operation. The water-cooled heat sink has been designed for excellent thermal performance as well as long-term stable cooling performance. We have also developed the thermal expansion controlled assembly technique to suppress the "smile". As a result, we have achieved an output power of over 200 W and a conversion efficiency of 58% from 940 nm LD bars under continuous wave (CW) operation with very low smile of 0.8 μm.

  6. High current, high bandwidth laser diode current driver

    NASA Technical Reports Server (NTRS)

    Copeland, David J.; Zimmerman, Robert K., Jr.

    1991-01-01

    A laser diode current driver has been developed for free space laser communications. The driver provides 300 mA peak modulation current and exhibits an optical risetime of less than 400 ps. The current and optical pulses are well behaved and show minimal ringing. The driver is well suited for QPPM modulation at data rates up to 440 Mbit/s. Much previous work has championed current steering circuits; in contrast, the present driver is a single-ended on/off switch. This results in twice the power efficiency as a current steering driver. The driver electrical efficiency for QPPM data is 34 percent. The high speed switch is realized with a Ku-band GaAsFET transistor, with a suitable pre-drive circuit, on a hybrid microcircuit adjacent to the laser diode.

  7. High-power diode lasers and their direct industrial applications

    NASA Astrophysics Data System (ADS)

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

    1995-04-01

    The paper summarizes activities of the two Fraunhofer-Institutes ILT and IPT concerning the development of high-power laser-diode stacks and their direct industrial applications. With microchannel coolers in copper technology and ultra-precision machined micro-optics a stack of 330 - 400 W total power with a maximum intensity of the focused beam of 2 104 W/cm2 has been built and tested in first applications. By further improvements of the lens-fabrication and -alignment technology as well as increase of the number of stacked diodes an output power in the kW-range and intensities up to about 105 W/cm2 shall be achieved in the near future. Applications of such laser sources in surface technology, in the processing of plastics, in laser-assisted machining and in brazing are discussed.

  8. Research and development for improved lead-salt diode lasers

    NASA Technical Reports Server (NTRS)

    Butler, J. F.

    1976-01-01

    A substantial increase in output power levels for lead-salt diode lasers, through the development of improved fabrication methods, as demonstrated. The goal of 1 mW of CW, single-mode, single-ended power output, was achieved, with exceptional devices exhibiting values greater than 8 mW. It was found that the current tuning rate could be controlled by adjusting the p-n junction depth, allowing the tuning rate to be optimized for particular applications. An unexpected phenomenon was encountered when crystal composition was observed to be significantly altered by annealing at temperatures as low as 600 C; the composition was changed by transport of material through the vapor phase. This effect caused problems in obtaining diode lasers with the desired operating characteristics. It was discovered that the present packaging method introduces gross damaging effects in the laser crystal through pressure applied by the C-bend.

  9. Dye-enhanced diode laser photocoagulation of choroidal neovascularizations

    NASA Astrophysics Data System (ADS)

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

    1994-06-01

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

  10. Effect of 655-nm diode laser on dog sperm motility.

    PubMed

    Corral-Baqués, M I; Rigau, T; Rivera, M; Rodríguez, J E; Rigau, J

    2005-01-01

    Sperm motility depends on energy consumption. Low-level laser irradiation increases adenosin triphosphate (ATP) production and energy supply to the cell. The aim of this study is to analyse whether the irradiation affects the parameters that characterise dog sperm motility. Fresh dog sperm samples were divided into four groups and irradiated with a 655-nm continuous-wave diode laser with varying doses: 0 (control), 4, 6 and 10 J/cm(2). At 0, 15 and 45 min following irradiation, pictures were taken of all the groups in order to study motility with computer-aided sperm analysis (CASA). Functional tests were also performed. Average path velocity (VAP), linear coefficient (Lin) and beat cross frequency (BCF) were statistically and significantly different when compared to the control. The functional tests also showed a significant difference. At these parameters, the 655-nm continuous-wave diode laser improves the speed and linear coefficient of the sperm.

  11. 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.

  12. Infrared laser diode with visible illuminator for biomedical stimulation

    NASA Astrophysics Data System (ADS)

    Strek, Wieslaw; Podbielska, Halina; Szafranski, C.; Kuzmin, Andrei N.; Ges, J. A.; Ryabtsev, Gennadii I.

    1995-02-01

    The special laser diode device (LDD) leasing in the near infrared region (IR) with two wavelengths: (lambda) 1 equals 850 nm and (lambda) 2 equals 1000 nm, designed for laser therapy, is presented. This device is characterized by a unique feature, namely a separate built-in illuminator, operating in 670 nm. The special construction of LDD and the illuminator enables the user to visualize exactly the surface irradiated by IR radiation. The exposure time and the output of laser power are also controlled and can be displayed on the LED monitor at the front panel. This new device, described here, is compact, low cost, and user friendly.

  13. Polarization control in ridge-waveguide-laser diodes

    SciTech Connect

    Amann, M.

    1987-04-20

    The polarization dependence of the gain/current relation and threshold current of quasi-index-guided laser diodes is analyzed for the case of lambda = 1.3 ..mu..m InGaAsP-InP ridge-waveguide lasers. Thereby it is shown that three different regimes for the stripe width and the lateral effective index discontinuity can be distinguished where one modal polarization (TE or TM) predominates. The significance of this finding on laser design and polarization control is discussed, and a comparison is performed on experimental results.

  14. Two-Pass, Diode-Pumped Nd:YAG Slab Laser Head

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry

    1992-01-01

    Neodymium/yttrium aluminum garnet (Nd:YAG) ring-laser head designed for compactness, simplicity, and increased efficiency for side pumping by diode lasers. Laser head includes two linear arrays of diode lasers, two fused-silica collimating rods, and Nd:YAG slab. Slab mounted on finned copper block, providing good thermal dissipation.

  15. Electrical and optical study of semiconductor laser diodes and materials

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia

    1987-01-01

    The characterization of a 2-D diode laser array from McDonald Douglas has been completed. The array consisted of 8 linear arrays of approximately 11 mm x 0.18 mm. Each array has between 7 and 8 diodes per mm. The threshold current is approximately 15 amps. The power output vs drive current (above threshold) of the array was measured. A peak power of 50 W was obtained at a drive current of 26 amps. Its far field pattern has a double lobe.

  16. Diode laser: In treatment of recurrent verrucous leukoplakia

    PubMed Central

    Giri, Debanti; Agarwal, Nitin; Sinha, Abhishek; Srivastava, Sunita; Mishra, Anuj

    2016-01-01

    Laser first came into light in 1960 and had been used extensively in various fields of medicine. Laser has been experimented in the various dental field, and its utility is being recognized and established well in the dentistry. Lasers are widely used for a number of procedures such as cavity preparation, scaling, and root planning, surgical procedures like excision of soft tissue growths, etc., Improved healing, hemostasis, and sutureless excisions are some of the many advantages of laser over conventional treatment modalities. It is because of these advantages that laser is becoming more and more popular as a treatment option in various aspects of dentistry. We hereby present a case report, where we have used diode laser for surgical management of a proliferative verrucous leukoplakia (PVL), because of its many advantages over conventional methods. It presents very specific characteristics, mainly a more aggressive biological behavior than other forms of leukoplakia expressed by: A tendency toward multifocality (field cancerization); a high prospect of recurrence; and a high rate of malignant transformation, which can range between 40% and 100% in a follow-up period of 4.4–11.6 years. In this case, we evaluated the advantages of diode laser for the treatment of verrucous leukoplakia, where the results that we obtained were excellent. The patient had come for evaluation till the time of complete healing. PMID:27307679

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

    NASA Astrophysics Data System (ADS)

    Terada, Masaki; Nakamura, Hideo

    2003-03-01

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

  18. Diode laser: In treatment of recurrent verrucous leukoplakia.

    PubMed

    Giri, Debanti; Agarwal, Nitin; Sinha, Abhishek; Srivastava, Sunita; Mishra, Anuj

    2016-01-01

    Laser first came into light in 1960 and had been used extensively in various fields of medicine. Laser has been experimented in the various dental field, and its utility is being recognized and established well in the dentistry. Lasers are widely used for a number of procedures such as cavity preparation, scaling, and root planning, surgical procedures like excision of soft tissue growths, etc., Improved healing, hemostasis, and sutureless excisions are some of the many advantages of laser over conventional treatment modalities. It is because of these advantages that laser is becoming more and more popular as a treatment option in various aspects of dentistry. We hereby present a case report, where we have used diode laser for surgical management of a proliferative verrucous leukoplakia (PVL), because of its many advantages over conventional methods. It presents very specific characteristics, mainly a more aggressive biological behavior than other forms of leukoplakia expressed by: A tendency toward multifocality (field cancerization); a high prospect of recurrence; and a high rate of malignant transformation, which can range between 40% and 100% in a follow-up period of 4.4-11.6 years. In this case, we evaluated the advantages of diode laser for the treatment of verrucous leukoplakia, where the results that we obtained were excellent. The patient had come for evaluation till the time of complete healing.

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

    NASA Astrophysics Data System (ADS)

    Reinl, S.

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

  20. 405 nm Light exposure of osteoblasts and inactivation of bacterial isolates from arthroplasty patients: potential for new disinfection applications?

    PubMed

    McDonald, R S; Gupta, S; Maclean, M; Ramakrishnan, P; Anderson, J G; MacGregor, S J; Meek, R M D; Grant, M H

    2013-01-01

    Infection rates after arthroplasty surgery are between 1-4 %, rising significantly after revision procedures. To reduce the associated costs of treating these infections, and the patients' post-operative discomfort and trauma, a new preventative method is required. High intensity narrow spectrum (HINS) 405 nm light has bactericidal effects on a wide range of medically important bacteria, and it reduced bacterial bioburden when used as an environmental disinfection method in a Medical Burns Unit. To prove its safety for use for environmental disinfection in orthopaedic theatres during surgery, cultured osteoblasts were exposed to HINS-light of intensities up to 15 mW/cm2 for 1 h (54 J/cm2). Intensities of up to 5 mW/cm2 for 1 h had no effect on cell morphology, activity of alkaline phosphatase, synthesis of collagen or osteocalcin expression, demonstrating that under these conditions this dose is the maximum safe exposure for osteoblasts; after exposure to 15 mW/cm2 all parameters of osteoblast function were significantly decreased. Viability (measured by protein content and Crystal Violet staining) of the osteoblasts was not influenced by exposure to 5 mW/cm2 for at least 2 h. At 5 mW/cm2 HINS-light is an effective bactericide. It killed 98.1 % of Staphylococcus aureus and 83.2 % Staphylococcus epidermis populations seeded on agar surfaces, and is active against both laboratory strains and clinical isolates from infected hip and knee arthroplasties. HINS-light could have potential for development as a method of disinfection to reduce transmission of bacteria during arthroplasty, with wider applications in diverse surgical procedures involving implantation of a medical device. PMID:23471732

  1. 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.

  2. 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.

  3. Extended ultrahigh-Q-cavity diode laser.

    PubMed

    Xie, Zhenda; Liang, Wei; Savchenkov, Anatoliy A; Lim, Jinkang; Burkhart, Jan; McDonald, Mickey; Zelevinsky, Tanya; Ilchenko, Vladimir S; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2015-06-01

    We report on a study of a 698 nm extended cavity semiconductor laser with intracavity narrowband optical feedback from a whispering gallery mode resonator. This laser comprises an ultrahigh-Q (>10(10)) resonator supporting stimulated Rayleigh scattering, a diffraction grating wavelength preselector, and a reflective semiconductor amplifier. Single longitudinal mode lasing is characterized with sub-kilohertz linewidth and a 9 nm coarse tuning range. The laser has a potential application for integration with the 1S0-3P0 strontium transition to create compact precision atomic clocks. PMID:26030566

  4. 5 W frequency stabilized 976 nm tapered diode lasers

    NASA Astrophysics Data System (ADS)

    Friedmann, Patrick; Gilly, Jürgen; Moritz, Stefan; Ostendorf, Ralf; Kelemen, Márc T.

    2008-02-01

    More and more applications, like tunable frequency doubling of diode lasers for blue-green outputs, non linear spectroscopy, or pump laser sources for fiber lasers necessitate diffraction-limited tunable narrow linewidths and high output powers in the multiwatt regime. For these applications, tapered lasers based on a tapered amplifier with gain-guided design can be used in an external cavity set up to guarantee both - frequency stabilization and tunability. We have realized frequency stabilized high-power ridge-waveguide tapered diode lasers with more than 4W of cw output power. These low modal gain, single quantum well InGaAs/AlGaAs devices emitting between 920nm and 1064nm were grown by molecular beam epitaxy. Tapered single emitters consist of an index-guided ridge section and a gain-guided taper section with an overall length of 3.5mm. The taper angle was 6°. With a high-reflectivity coating on the rear facet and an antireflection coating on the front facet more than 10W of output power have been demonstrated. To optimize the beam quality at higher output power the two different sections have been operated by different operation currents. For this purpose the tapered diodes have been mounted p-side down on structured submounts. For wavelength tunability and frequency stabilization the tapered diodes, provided with AR coatings on both facets, have been used in external cavity setup in Littrow configuration. The influence of the different operation currents on the electrooptical and beam characteristics has been carefully investigated in detail. Within this operation mode a nearly diffraction limited behavior up to 5W has been established.

  5. 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.

  6. Packaging of hard solder 500W QCW diode laser array

    NASA Astrophysics Data System (ADS)

    Li, Xiaoning; Wang, Jingwei; Hou, Dong; Nie, Zhiqiang; Liu, Xingsheng

    2016-03-01

    The package structure critically influences the major characteristics of diode laser, such as thermal behavior, output power, wavelength and smile effect. In this work, a novel micro channel cooler (MCC) for stack array laser with good heat dissipation capability and high reliability is presented. Numerical simulations of thermal management with different MCC structure are conducted and analyzed. Based on this new MCC packaging structure, a series of QCW 500W high power laser arrays with hard solder packaging technology has been fabricated. The performances of the laser arrays are characterized. A narrow spectrum of 3.12 nm and an excellent smile value are obtained. The lifetime of the laser array is more than 1.38×109 shots and still ongoing.

  7. New ytterbium-phosphate glass for diode-pumped lasers

    SciTech Connect

    Galagan, B I; Glushchenko, I N; Denker, B I; Sverchkov, S E; Kisel', V E; Kuril'chik, S V; Kuleshov, N V

    2009-10-31

    A new ytterbium laser glass based on an alumoborophosphate composition is developed. It is shown that the chemical and thermal stabilities of this glass are record-high for phosphate glasses and that its spectral and luminescent characteristics compare well with popular laser glasses. A mould of laser-quality glass doped with ytterbium with a concentration of 5x10{sup 20} cm{sup -3} is synthesised. Active laser elements 5x5x2 mm in size are prepared from this glass for longitudinal diode pumping. These elements were used to fabricate a laser, whose output power in the cw regime reached 783 mW and maximum slope efficiency was 28.9%. Pulses with a duration of {approx}150 fs and a peak power of about 5 kW are obtained in the passive mode-locking regime. (active media)

  8. Advances in tunable diode laser technology

    NASA Technical Reports Server (NTRS)

    Lo, W.

    1980-01-01

    The improvement of long-term reliability, the purification of mode properties, and the achievement of higher-temperature operation were examined. In reliability studies a slow increase in contact resistance during room temperature storage for lasers fabricated with In-Au or In-Pt contacts was observed. This increase is actually caused by the diffusion of In into the surface layer of laser crystals. By using a three layered structure of In-Au-Pt or In-Pt-Au, this mode of degradation was reduced. In characterizing the mode properties, it was found that the lasers emit in a highly localized, filamentary manner. For widestripe lasers the emission occurs near the corners of the junction. In order to achieve single-mode operation, stripe widths on the order of 8-10 micrometers are needed. Also, it was found that room temperature electroluminescence is possible near 4.6 micrometers.

  9. Laser diode-to-singlemode fiber butt-coupling and extremely-short-external-cavity laser diodes: Analysis, realization and applications

    NASA Astrophysics Data System (ADS)

    Sidorin, Yakov Sergeevich

    1998-11-01

    The butt-coupling of a Fabry-Perot semiconductor laser diode and a singlemode optical fiber was realized and characterized in the near field. A novel butt-coupling model was developed and found very effective in describing all physical phenomena that occur when the butt-coupling parameters are varied over a wide range. The strong external optical feedback to the laser diode cavity that is present at extremely-short separations between the laser diode and the fiber is advantageously used to realize an extremely-short external cavity laser diode. By varying the length of the external cavity, the operational characteristics of this external cavity laser diode are controlled in a predictable and repeatable manner; a wavelength tunable laser diode source based on this effect was developed and analyzed. Another realization of an extremely short external cavity tunable laser diode, based on a closely spaced external filter with variable characteristics, was demonstrated. A potential application of the butt-coupling technique for light collection in an optical recording head is discussed. The work presented here is a research tool that can be used to facilitate the design of extremely- short external cavity laser diodes, which in many ways are technologically novel.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  11. High power, high efficiency diode pumped Raman fiber laser

    NASA Astrophysics Data System (ADS)

    Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Dahan, Asaf; Ter-Gabrielyan, Nikolay; Pattnaik, Radha K.; Dubinskii, Mark

    2016-06-01

    We demonstrate a high power high efficiency Raman fiber laser pumped directly by a laser diode module at 976 nm. 80 Watts of CW power were obtained at a wavelength of 1020 nm with an optical-to-optical efficiency of 53%. When working quasi-CW, at a duty cycle of 30%, 85 W of peak power was produced with an efficiency of 60%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the 2nd Stokes. In addition, significant brightness enhancement of the pump beam is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge, this is the highest power Raman fiber laser directly pumped by laser diodes, which also exhibits a record efficiency for such a laser. In addition, it is the highest power Raman fiber laser (regardless of pumping source) demonstrated based on a GRIN fiber.

  12. Polarization competition in quasi-index-guided laser diodes

    SciTech Connect

    Amann, M.; Stegmueller, B.

    1988-03-15

    The mechanism of polarization competition in laser diodes with a lateral quasi-index-guiding (QIG) structure is analyzed generally by way of the effective index approximation using a simplified QIG laser model. The influence of the relevant waveguide parameters on the polarization-dependent threshold current of QIG laser diodes is investigated in detail by example of lambda = 1.3-..mu..m ridge-waveguide lasers. Thereby, it is found that for intermediate values of the effective index step, the TM mode exhibits a higher gain and lower threshold current, whereas for pure gain guiding or strong index guiding, the TE mode prevails. This behavior, which compares excellently to published experimental results, is proven as a basic feature of the two-dimensional waveguiding mechanism in QIG devices. Accordingly, the effect of stress-induced anisotropy of the optical gain has been found to be of minor importance as the origin for TM-polarized QIG lasers made from lattice-matched heterostructures. It is further demonstrated that, for certain device parameters, the QIG lasers with a small effective index step exhibit somewhat higher threshold currents than the purely gain-guided devices of identical geometry.

  13. 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.

  14. Optimization of rod diameter in solid state lasers side pumped with multiple laser diode arrays

    NASA Technical Reports Server (NTRS)

    Sims, Newton, Jr.; Chamblee, Christyl M.; Barnes, Norman P.; Lockard, George E.; Cross, Patricia L.

    1992-01-01

    Results of a study to determine the optimum laser rod diameter for maximum output energy in a solid state neodymium laser transversely pumped with multiple laser diode arrays are reported here. Experiments were performed with 1.0 mm, 1.5 mm and 2.0 mm rod radii of both neodymium doped Y3Al5O12 (Nd:YAG) and La2Be2O5 (Nd:BeL) pumped with laser diode arrays having a maximum combined energy of 10.5 mJ. Equations were derived which predict the optimum rod radius and corresponding output mirror reflectivity for a given laser material and total pump energy. Predictions of the equations agreed well with the experiments for each of the laser materials which possessed significantly different laser properties from one another.

  15. Suppression of beam steering in an injection-locked laser diode array

    SciTech Connect

    Brewer, L.R. )

    1991-12-09

    Experimental measurements were made to demonstrate that the degree of beam steering in an injection-locked laser diode array is related to the divergence of the master laser beam. For a collimated master laser beam the beam steering was suppressed. The injection-locked laser diode array beam steers with the master laser wavelength because only a portion of the divergent master laser beam satisfies the round trip mode condition.

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

    DOEpatents

    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.

  17. 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.

  18. Optimization of beam transformation system for laser-diode bars.

    PubMed

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

    2016-08-22

    An optimized beam transformation system (BTS) is proposed to improve the beam quality of laser-diode bars. Through this optimized design, the deterioration of beam quality after the BTS can be significantly reduced. Both the simulation and experimental results demonstrate that the optimized system enables the beam quality of a mini-bar (9 emitters) approximately equal to 5.0 mm × 3.6 mrad in the fast-axis and slow-axis. After beam shaping by the optimized BTS, the laser-diode beam can be coupled into a 100 μm core, 0.15 numerical aperture (NA) fiber with an output power of over 100 W and an electric-optical efficiency of 46.8%.

  19. Laser diode self-mixing technique for liquid velocimetry

    NASA Astrophysics Data System (ADS)

    Alexandrova, A.; Welsch, C. P.

    2016-09-01

    Using the self-mixing technique, or optical feedback interferometry, fluid velocity measurements of water seeded with titanium dioxide have been performed using a laser diode to measure the effect of the seeding particle concentration and also the pump speed of the flow. The velocimeter utilises commercially available laser diodes with a built-in photodiode for detection of the self-mixing effect. The device has demonstrated an accuracy better than 10% for liquid flow velocities up to 1.5 m/s with a concentration of scattering particles in the range of 0.8-0.03%. This is an improvement of one order of magnitude compared to previous experiments. The proposed velocimeter is to be developed further for application in gas-jet measurements.

  20. Diode laser based water vapor DIAL using modulated pulse technique

    NASA Astrophysics Data System (ADS)

    Pham, Phong Le Hoai; Abo, Makoto

    2014-11-01

    In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

  1. Optimization of beam transformation system for laser-diode bars.

    PubMed

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

    2016-08-22

    An optimized beam transformation system (BTS) is proposed to improve the beam quality of laser-diode bars. Through this optimized design, the deterioration of beam quality after the BTS can be significantly reduced. Both the simulation and experimental results demonstrate that the optimized system enables the beam quality of a mini-bar (9 emitters) approximately equal to 5.0 mm × 3.6 mrad in the fast-axis and slow-axis. After beam shaping by the optimized BTS, the laser-diode beam can be coupled into a 100 μm core, 0.15 numerical aperture (NA) fiber with an output power of over 100 W and an electric-optical efficiency of 46.8%. PMID:27557249

  2. 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.

  3. 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.

  4. Cs laser with unstable cavity transversely pumped by multiple diode lasers.

    PubMed

    Zhdanov, B V; Shaffer, M K; Knize, R J

    2009-08-17

    We have demonstrated a Cs vapor laser with an unstable resonator transversely pumped by 15 narrowband laser diode arrays. A slope efficiency of 43%, a total optical efficiency of 31% and a maximum output power 49 W were obtained with a pump power of 157 Watts. PMID:19687954

  5. High power, high efficiency, 2D laser diode arrays for pumping solid state lasers

    SciTech Connect

    Rosenberg, A.; McShea, J.C.; Bogdan, A.R.; Petheram, J.C.; Rosen, A.

    1987-11-01

    This document reports the current performance of 2D laser diode arrays operating at 770 nm and 808 nm for pumping promethium and neodymium solid state lasers, respectively. Typical power densities are in excess of 2kw/cm/sup 2/ with overall efficiencies greater than 30%.

  6. Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser

    NASA Technical Reports Server (NTRS)

    Coyle, Donald B.

    2008-01-01

    A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

  7. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  8. Analysis of steady-state characteristics of bistable laser diodes

    SciTech Connect

    Zhong Lichen; Guo Yili

    1987-05-01

    In this paper we analyze the steady-state characteristics of bistable semiconductor laser diode (BILD). A simple model for optical output of BILD is obtained using nonlinear rate equations for electron and photon densities. This model emphasizes the physical mechanisms and parameters responsible for the bistability, gives the state equation and explains the main features of BILD. Bistability with a very large hysteresis in P/sub 0/-P/sub 4/ characteristics is a distinctive feature of BILD.

  9. Analysis of diode lasers with lateral spatial variations in thickness

    NASA Astrophysics Data System (ADS)

    Streifer, W.; Burnham, R. D.; Scifres, D. R.

    1980-07-01

    Diode lasers with active and/or cladding regions whose thicknesses vary spatially parallel to the p-n junction are analyzed. It is shown that lateral real-refractive-index waveguiding occurs and that a diffusion gradient exists which propels the injected charges into the lasing modal volume. Lateral mode patterns and thresholds are calculated and sensitivity to higher-order lateral mode oscillation is evaluated for various stripe widths and spreading resistances. Results are shown to agree well with experimental data.

  10. Monolithically Peltier-cooled laser diodes

    NASA Astrophysics Data System (ADS)

    Hava, S.; Hunsperger, R. G.; Sequeira, H. B.

    1984-04-01

    A new method of cooling a GaAs/GaAlAs laser in an optical integrated circuit or on a discrete chip, by adding an integral thermoelectric (Peltier) cooling and heat spreading device to the laser, is presented. This cooling both reduces and stabilizes the laser junction temperature to minimize such deleterious effects as wavelength drift due to heating. A unified description of the electrical and thermal properties of a monolithic semiconductor mesa structure is given. Here it is shown that an improvement in thermal characteristics is obtained by depositing a relatively thick metallic layer, and by using this layer as a part of an active Peltier structure. Experimental results reveal a 14-percent increase in emitted power (external quantum efficiency) due to passive heat spreading and a further 8-percent if its Peltier cooler is operated. Fabrication techniques used to obtain devices exhibiting the above performance characteristics are given.

  11. Monolithically Peltier-cooled laser diodes

    SciTech Connect

    Hava, S.; Hunsperger, R.G.; Sequeira, H.B.

    1984-04-01

    A new method of cooling a GaAs/GaAlAs laser in an optical integrated circuit or on a discrete chip, by adding an integral thermoelectric (Peltier) cooling and heat spreading device to the laser, is presented. This cooling both reduces and stabilizes the laser junction temperature to minimize such deleterious effects as wavelength drift due to heating. A unified description of the electrical and thermal properties of a monolithic semiconductor mesa structure is given. Here it is shown that an improvement in thermal characteristics is obtained by depositing a relatively thick metallic layer, and by using this layer as a part of an active Peltier structure. Experimental results reveal a 14-percent increase in emitted power (external quantum efficiency) due to passive heat spreading and a further 8-percent if its Peltier cooler is operated. Fabrication techniques used to obtain devices exhibiting the above performance characteristics are given. 21 references.

  12. Broadly tunable, longitudinally diode-pumped Alexandrite laser

    NASA Astrophysics Data System (ADS)

    Strotkamp, M.; Witte, U.; Munk, A.; Hartung, A.; Gausmann, S.; Hengesbach, S.; Traub, M.; Hoffmann, H.-D.; Hoeffner, J.; Jungbluth, B.

    2014-02-01

    We present design and first performance data of a broadly tunable Alexandrite laser longitudinally pumped by a newly developed high brightness single emitter diode laser module with output in the red spectral range. Replacing the flashlamps, which are usually used for pumping Alexandrite, will increase the efficiency and maintenance interval of the laser. The pump module is designed as an optical stack of seven single-emitter laser diodes. We selected an optomechanical concept for the tight overlay of the radiation using a minimal number of optical components for collimation, e.g. a FAC and a SAC lens, and focusing. The module provides optical output power of more than 14 W (peak pulse output in the focus) with a beam quality of M2 = 41 in the fast axis and M2 = 39 in the slow axis. The Alexandrite crystal is pumped from one end at a repetition rate of 35 Hz and 200μs long pump pulses. The temperature of the laser crystal can be tuned to between 30 °C and 190 °C using a thermostat. The diode-pumped Alexandrite laser reaches a maximum optical-optical efficiency of 20 % and a slope efficiency of more than 30 % in fundamental-mode operation (M2 < 1.10). When a Findlay-Clay analysis with four different output couplers is conducted, the round-trip loss of the cavity is determined to be around 1 %. The wavelength is tunable to between 755 and 788 nm via crystal temperature or between 745 and 805 nm via an additional Brewster prism.

  13. 450 nm diode laser: A new help in oral surgery

    PubMed Central

    Fornaini, Carlo; Rocca, Jean-Paul; Merigo, Elisabetta

    2016-01-01

    AIM To describe the performance of 450 nm diode laser in oral surgery procedures. METHODS The case described consisted of the removal of a lower lip fibroma through a blue diode laser (λ = 450 nm). RESULTS The efficacy of this device, even at very low power (1W, CW), allows us to obtain very high intra and postoperative comfort for the patient, even with just topical anaesthesia and without needing suture. The healing process was completed in one week and, during the follow-up, the patient did not report any problems, pain or discomfort even without the consumption of any kind of drugs, such as painkillers and antibiotics. The histological examination performed by the pathologist showed a large area of fibrous connective tissue with some portions of epithelium-connective detachments and a regular incision with very scanty areas of carbonization. CONCLUSION The 450 nm diode laser proved of being very efficient in the oral soft tissue surgical procedures, with no side effects for the patients.

  14. 450 nm diode laser: A new help in oral surgery

    PubMed Central

    Fornaini, Carlo; Rocca, Jean-Paul; Merigo, Elisabetta

    2016-01-01

    AIM To describe the performance of 450 nm diode laser in oral surgery procedures. METHODS The case described consisted of the removal of a lower lip fibroma through a blue diode laser (λ = 450 nm). RESULTS The efficacy of this device, even at very low power (1W, CW), allows us to obtain very high intra and postoperative comfort for the patient, even with just topical anaesthesia and without needing suture. The healing process was completed in one week and, during the follow-up, the patient did not report any problems, pain or discomfort even without the consumption of any kind of drugs, such as painkillers and antibiotics. The histological examination performed by the pathologist showed a large area of fibrous connective tissue with some portions of epithelium-connective detachments and a regular incision with very scanty areas of carbonization. CONCLUSION The 450 nm diode laser proved of being very efficient in the oral soft tissue surgical procedures, with no side effects for the patients. PMID:27672639

  15. Wave optics simulation of diode pumped alkali laser (DPAL)

    NASA Astrophysics Data System (ADS)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio

    2016-03-01

    A numerical simulation code for a diode pumped alkali laser (DPAL) was developed. The code employs the Fresnel- Kirchhoff diffraction integral for both laser mode and pump light propagations. A three-dimensional rate equation set was developed to determine the local gain. The spectral divergence of the pump beam was represented by a series of monochromatic beams with different wavelengths. The calculated results showed an excellent agreements with relevant experimental results. It was found that the main channel of the pump power drain is the spontaneous emission from the upper level of the lasing transition.

  16. Quasi-stadium laser diodes with an unstable resonator condition.

    PubMed

    Fukushima, Takehiro; Harayama, Takahisa; Davis, Peter; Vaccaro, Pablo O; Nishimura, Takehiro; Aida, Tahito

    2003-03-15

    We have observed lasing in a complicated eigenmode of a quasi-stadium laser diode with an unstable resonator consisting of two curved end mirrors obeying an unstable resonator condition and two straight sidewall mirrors. The laser was fabricated by application of a reactive-ion-etching technique to a molecular beam epitaxy-grown graded-index separate-confinement heterostructure single-quantum-well GaAs/AlGaAs structure. The far-field pattern shows that the lasing mode corresponds to the complicated lowest-loss mode obtained numerically by an extended Fox-Li method. PMID:12659262

  17. An ac microcalorimeter employing a diode laser as a heater

    NASA Astrophysics Data System (ADS)

    Marone, M. J.; Payne, J. E.

    1997-12-01

    We have built an ac microcalorimeter which uses a diode laser as the heater. The absence of a contact heater reduces the total addendum. This method has several advantages over the typical quartz lamp and mechanical chopper wheel configuration. The laser is modulated by a lock-in amplifier which provides a wider choice of operating frequencies, typically from 0.2 to 50 Hz. The microcalorimeter has been used from near room temperature to 5 K. Single-crystal samples of YBCO with a mass as small as 4 μg have been measured. The device is particularly useful in the study of whiskers and other very small samples.

  18. 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.

  19. Ion-implanted planar-buried-heterostructure diode laser

    DOEpatents

    Brennan, Thomas M.; Hammons, Burrell E.; Myers, David R.; Vawter, Gregory A.

    1991-01-01

    A Planar-Buried-Heterostructure, Graded-Index, Separate-Confinement-Heterostructure semiconductor diode laser 10 includes a single quantum well or multi-quantum well active stripe 12 disposed between a p-type compositionally graded Group III-V cladding layer 14 and an n-type compositionally graded Group III-V cladding layer 16. The laser 10 includes an ion implanted n-type region 28 within the p-type cladding layer 14 and further includes an ion implanted p-type region 26 within the n-type cladding layer 16. The ion implanted regions are disposed for defining a lateral extent of the active stripe.

  20. Calculation and comparison of thermal effect in laser diode pumped slab lasers with different pumping structures

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Jiang, Nan; Wang, Yuefeng; Dong, Wei; Niu, Yanxiong

    2008-03-01

    Laser diode (LD) pumped slab laser, as an important high average power solid-state laser, is a promising laser source in military and industrial fields. The different laser diode pumping structures lead to different thermal effect in the slab gain medium. The thermal and stress analysis of slab laser with different pumping structure are performed by finite element analysis (FEA) with the software program ANSYS. The calculation results show that the face pumped and cooled laser results in a near one-dimension temperature distribution and eliminates thermal stress induced depolarization. But the structure is low pump efficiency due to the small thickness of slabs and the requirement to cool and pump through the same faces. End-pumped slab laser is high pump efficiency and excellent mode match, but its pumping arrangement is fairly complicated. The edge-pumped face-cooling slab laser's pump efficiency is better than face-pumping, and its pumping structure is simpler than end-pumped laser, but the tensile stress on surfaces may initiate failure of the gain medium so it is important to design so that the stress is well below the stress fracture limit. The comparison of the thermal effects with different pumping structure shows that, the edge-pumped slab laser has engineering advantages in high power slab laser's application. Furthermore, the end-pumped slab laser tends to get the best beam quality, so it is fit for the application which has a special requirement on laser beam quality.

  1. Generation of turquoise light by sum frequency mixing of a diode-pumped solid-state laser and a laser diode in periodically poled KTP.

    PubMed

    Johansson, Sandra; Spiekermann, Stefan; Wang, Shunhua; Pasiskevicius, Valdas; Laurell, Fredrik; Ekvall, Katrin

    2004-10-01

    We report a simple and efficient method to achieve visible light by sum-frequency mixing radiation from a diode-pumped solid-state laser and a laser diode in a periodically poled KTiOPO4 crystal. Since high-power laser diodes are available at a wide range of wavelengths, it is thereby possible to obtain essentially any wavelength in the visible spectrum by appropriate choice of lasers. For demonstration we choose to construct a light source in the blue-green region. A turquoise output power of 4.0 mW was achieved.

  2. Generation of turquoise light by sum frequency mixing of a diode-pumped solid-state laser and a laser diode in periodically poled KTP

    NASA Astrophysics Data System (ADS)

    Johansson, Sandra; Spiekermann, Stefan; Wang, Shunhua; Pasiskevicius, Valdas; Laurell, Fredrik; Ekvall, Katrin

    2004-10-01

    We report a simple and efficient method to achieve visible light by sum-frequency mixing radiation from a diode-pumped solid-state laser and a laser diode in a periodically poled KTiOPO4 crystal. Since high-power laser diodes are available at a wide range of wavelengths, it is thereby possible to obtain essentially any wavelength in the visible spectrum by appropriate choice of lasers. For demonstration we choose to construct a light source in the blue-green region. A turquoise output power of 4.0 mW was achieved.

  3. 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.

  4. 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.

  5. Precision UV laser scribing for cleaving mirror facets of GaN-based laser diodes

    NASA Astrophysics Data System (ADS)

    Krüger, O.; Kang, J.-H.; Spevak, M.; Zeimer, U.; Einfeldt, S.

    2016-04-01

    Laser scribing with a nanosecond-pulsed UV laser operating at 355 nm was used to create precise perforation for die separation of GaN-based laser diodes. Machining depth of single- and multiple-pass scribing was investigated. For pulse energies between 1 and 45 µJ at a pulse repetition frequency of 20 kHz and single scan at 100 mm/min, scribe depths from 15 to 180 µm were obtained. Processing parameters were adjusted to minimize the formation of microcracks due to laser-induced local heating. By using the laser skip-and-scribe technique, the propagation of the cleavage plane could be controlled, irregular breaking could be minimized, and die yield could be improved. Smooth mirror facets with low density of terraces were formed by cleaving. In the vicinity of the laser-treated zone, no detrimental effects on the crystal quality of the multi-quantum wells could be detected by cathodoluminescence. The electro-optical characteristics of broad-area laser diodes fabricated by the laser-assisted process were similar to the ones fabricated using the conventional diamond-tip edge-scribing technique that suffers from low die yield. Our results demonstrate that nanosecond-pulsed UV laser scribing followed by cleaving is a powerful technique for the formation of mirror facets of GaN-based laser diodes.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  7. Characterization of High-power Quasi-cw Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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. Performance and comprehensive characterization data of Quasi-CW, High-power, laser diode arrays is presented.

  8. Nd:GdVO4 ring laser pumped by laser diodes

    NASA Astrophysics Data System (ADS)

    Hao, E. J.; Li, T.; Wang, Z. D.; Zhang, Y.

    2013-02-01

    The design and operation of a laser diode-pumped Nd:GdVO4 ring laser is described. A composite crystal (Nd:GdVO4/YVO4) with undoped ends is single-end pumped by a fiber-coupled laser diode (LD) at 808 nm. A four-mirror ring cavity is designed to keep the laser operating unidirectionally, which eliminates spatial hole burning in the standing-wave cavity. This laser can operate either as continuous wave (CW) or Q-switched. The single-frequency power obtained was 9.1 W at 1063 nm. Q-switched operation produced 0.23 mJ/pulse at 20 kHz in the fundamental laser.

  9. 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.

  10. Theoretical and experimental aspects of laser cutting with a direct diode laser

    NASA Astrophysics Data System (ADS)

    Costa Rodrigues, G.; Pencinovsky, J.; Cuypers, M.; Duflou, J. R.

    2014-10-01

    Recent developments in beam coupling techniques have made it possible to scale up the power of diode lasers with a laser beam quality suitable for laser cutting of metal sheets. In this paper a prototype of a Direct Diode Laser (DDL) source (BPP of 22 mm-mrad) is analyzed in terms of efficiency and cut performance and compared with two established technologies, CO2 and fiber lasers. An analytical model based on absorption calculations is used to predict the performance of the studied laser source with a good agreement with experimental results. Furthermore results of fusion cutting of stainless steel and aluminium alloys as well as oxygen cutting of structural steel are presented, demonstrating that industrial relevant cutting speeds with high cutting quality can now be achieved with DDL.

  11. Optical communication with laser diode arrays

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1984-01-01

    The performance of a direct-detection optical communication system in which the laser transmitter sends short optical pulses of selected nonoverlapping center frequencies is analysed. This modulation format, in which a single light pulse is sent in one of M time slots at one of N optical center frequencies, is referred to as color coded optical pulse position modulation (CCPPM). The optimum energy-efficiency of this system, as measured by the channel capacity in nats per photon, exceeds that of ordinary optical pulse position modulation which uses a pulsed laser of fixed optical frequency. Reliable communication at optimal energy efficiency is easily achieved through the use of modest block length Reed-Solomon codes with the code words represented as CCPPM symbols.

  12. Case studies of industrial applications of high-power diode laser in Finland

    NASA Astrophysics Data System (ADS)

    Hovikorpi, Jari; Jansson, Anssi; Salminen, Antti

    2003-06-01

    The high power diode laser is a new industrial tool. It has several advantages and disadvantages compared to the conventional industrially used CO2 and Nd:YAG laser. The most promising areas of application of diode laser have been considered to be thin sheet welding and hardening. Quite a few feasibility studies of the use of diode laser have been carried out in Finland. So far there has been some application in which diode laser is the most suitable laser. Typically, the HPDL is integrated to an industrial robot. The welding of stainless steel housing, car door lock and catalytic converters are typical examples of applications in which diode laser has technological as well as economical advantages over the conventional laser and welding techniques. The welding of these products requires good control over the heat input, short through put time and low investment. The weld cross-section of a diode laser weld is, because of conduction limited welding process, more suitable for these applications than the keyhole welding. Hardening of a large gear wheel presents also a good example of an application in which the diode laser makes it possible to economically produce structures that have not earlier been possible. Hardening requires a special form of heat delivery in order to ensure evenly hardened zone and acceptable quality. The application was performed with two high power diode lasers. The case studies of these four applications are presented and discussed in details in this paper.

  13. Packaging of complete indium-free high reliable and high power diode laser array

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Li, Xiaoning; Feng, Feifei; Liu, Yalong; Hou, Dong; Liu, Xingsheng

    2015-02-01

    High power diode lasers have been widely used in many fields. For many applications, a diode laser needs to be robust under on-off power-cycling as well as environmental thermal cycling conditions. To meet the requirements, the conduction cooled single bar CS-packaged diode laser arrays must have high durability to withstand thermal fatigue and long lifetime. In this paper, a complete indium-free bonding technology is presented for packaging high power diode laser arrays. Numerical simulations on the thermal behavior of CS-packaged diode laser array with different packaging structure were conducted and analyzed. Based on the simulation results, the device structure and packaging process of complete indium-free CS-packaged diode laser array were optimized. A series of high power hard solder CS (HCS) diode laser arrays were fabricated and characterized. Under the harsh working condition of 90s on and 30s off, good lifetime was demonstrated on 825nm 60W single bar CS-packaged diode laser with a lifetime test of more than 6100hours achieved so far with less 5% power degradation and less 1.5nm wavelength shift. Additionally, the measurement results indicated that the lower smile of complete indium-free CS-packaged diode laser arrays were achieved by advanced packaging process.

  14. Effect of interface layer on the performance of high power diode laser arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Wang, Jingwei; Xiong, Lingling; Li, Xiaoning; Hou, Dong; Liu, Xingsheng

    2015-02-01

    Packaging is an important part of high power diode laser (HPLD) development and has become one of the key factors affecting the performance of high power diode lasers. In the package structure of HPLD, the interface layer of die bonding has significant effects on the thermal behavior of high power diode laser packages and most degradations and failures in high power diode laser packages are directly related to the interface layer. In this work, the effects of interface layer on the performance of high power diode laser array were studied numerically by modeling and experimentally. Firstly, numerical simulations using finite element method (FEM) were conducted to analyze the effects of voids in the interface layer on the temperature rise in active region of diode laser array. The correlation between junction temperature rise and voids was analyzed. According to the numerical simulation results, it was found that the local temperature rise of active region originated from the voids in the solder layer will lead to wavelength shift of some emitters. Secondly, the effects of solder interface layer on the spectrum properties of high power diode laser array were studied. It showed that the spectrum shape of diode laser array appeared "right shoulder" or "multi-peaks", which were related to the voids in the solder interface layer. Finally, "void-free" techniques were developed to minimize the voids in the solder interface layer and achieve high power diode lasers with better optical-electrical performances.

  15. 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.

  16. Selection strategy and reliability assessment for SILEX-communication laser diodes

    NASA Astrophysics Data System (ADS)

    Loeffler, Roland; Menke, Bodo

    1991-03-01

    Steps involved in the search for suitable laser diodes for Semiconductor laser Intersatellite Link EXperiment (SILEX) and evaluation of their capabilities in meeting qualification requirements are discussed. A baseline of the laser diode functional specifications is identified by synthesizing the SILEX system requirements and thereby predicting the desired diode characteristics. Samples of approximately 20 different laser diode types are submitted to comprehensive measurements of their characteristics, spectral widths, mode hopping behavior, far field patterns, wave front errors and astigmatisms under modulation. An evaluation program consisting of a conventional three temperature aging test and sensitivity and environmental tests is defined.

  17. 100  J-level nanosecond pulsed diode pumped solid state laser.

    PubMed

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

    2016-05-01

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

  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. 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.

  20. Three Hundred Patients Treated with Ultrapulsed 980 nm Diode Laser for Skin Disorders.

    PubMed

    Wollina, Uwe

    2016-01-01

    The use of lasers in skin diseases is quite common. In contrast to other laser types, medical literature about 980 nm ultrapulsed diode laser is sparse in dermatology. Herein, we report the use of ultrapulsed diode 980 nm laser in 300 patients with vascular lesions, cysts and pseudocysts, infectious disease, and malignant tumors. This laser is a versatile tool with excellent safety and efficacy in the hands of the experienced user. PMID:27688445

  1. Three Hundred Patients Treated with Ultrapulsed 980 nm Diode Laser for Skin Disorders

    PubMed Central

    Wollina, Uwe

    2016-01-01

    The use of lasers in skin diseases is quite common. In contrast to other laser types, medical literature about 980 nm ultrapulsed diode laser is sparse in dermatology. Herein, we report the use of ultrapulsed diode 980 nm laser in 300 patients with vascular lesions, cysts and pseudocysts, infectious disease, and malignant tumors. This laser is a versatile tool with excellent safety and efficacy in the hands of the experienced user.

  2. Three Hundred Patients Treated with Ultrapulsed 980 nm Diode Laser for Skin Disorders

    PubMed Central

    Wollina, Uwe

    2016-01-01

    The use of lasers in skin diseases is quite common. In contrast to other laser types, medical literature about 980 nm ultrapulsed diode laser is sparse in dermatology. Herein, we report the use of ultrapulsed diode 980 nm laser in 300 patients with vascular lesions, cysts and pseudocysts, infectious disease, and malignant tumors. This laser is a versatile tool with excellent safety and efficacy in the hands of the experienced user. PMID:27688445

  3. Three Hundred Patients Treated with Ultrapulsed 980 nm Diode Laser for Skin Disorders.

    PubMed

    Wollina, Uwe

    2016-01-01

    The use of lasers in skin diseases is quite common. In contrast to other laser types, medical literature about 980 nm ultrapulsed diode laser is sparse in dermatology. Herein, we report the use of ultrapulsed diode 980 nm laser in 300 patients with vascular lesions, cysts and pseudocysts, infectious disease, and malignant tumors. This laser is a versatile tool with excellent safety and efficacy in the hands of the experienced user.

  4. Diode laser processed crystalline silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Varlamov, S.; Eggleston, B.; Dore, J.; Evans, R.; Ong, D.; Kunz, O.; Huang, J.; Schubert, U.; Kim, K. H.; Egan, R.; Green, M.

    2013-03-01

    Line-focus diode laser is applied to advance crystalline silicon thin-film solar cell technology. Three new processes have been developed: 1) defect annealing/dopant activation; 2) dopant diffusion; 3) liquid phase crystallisation of thin films. The former two processes are applied to either create a solar cell device from pre-crystallised films or improve its performance while reducing the maximum temperature experienced by substrate. The later process is applied to amorphous silicon films to obtain high crystal and electronic quality material for thin-film solar cells with higher efficiency potential. Defect annealing/dopant activation and dopant diffusion in a few micron thick poly-Si films are achieved by scanning with line-focus 808 nm diode laser beam at 15-24 kW/cm2 laser power and 2~6 ms exposure. Temperature profile in the film during the treatment is independent from laser power and exposure but determined by beam shape. Solar cell open-circuit voltages of about 500 mV after such laser treatments is similar or even higher than voltages after standard rapid-thermal treatments while the highest temperature experienced by glass is 300C lower. Amorphous silicon films can be melted and subsequently liquid-phase crystallised by a single scan of line laser beam at about 20 kW/cm2 power and 10-15 ms exposure. Solar cells made of laser-crystallised material achieve 557 mV opencircuit voltage and 8.4% efficiency. Electronic quality of such cells is consistent with efficiencies exceeding 13% and it is currently limited by research-level simplified cell metallisation.

  5. Development of Advanced Laser Diode Sources

    NASA Technical Reports Server (NTRS)

    Coleman, J. J.; Papen, G. C.

    1998-01-01

    The design and operation of InGaAs-GaAs-AlGaAs asymmetric cladding ridge waveguide distributed Bragg reflector lasers is presented. Targeted for the remote sensing of water vapor with absorption lines in the lambda approximately 930 nm region, these devices operate CW with threshold currents as low as 11 MA and slope efficiencies as high as 0.37 W/A. Tbey also operate with over 30-dB side-mode suppression, and the typical CW characteristic temperature, T(sub o), is 95 K.

  6. Diode-Laser-Based Spectrometer for Sensing Gases

    NASA Technical Reports Server (NTRS)

    Silver, Joel A.

    2005-01-01

    A diode-laser-based spectrometer has been developed for measuring concentrations of gases and is intended particularly for use in analyzing and monitoring combustion processes under microgravitational conditions in a drop tower or a spacecraft. This instrument is also well suited for use on Earth in combustion experiments and for such related purposes as fire-safety monitoring and monitoring toxic and flammable gases in industrial settings. Of the gas-sensing spectrometers available prior to the development of this instrument, those that were sensitive enough for measuring the combustion gases of interest were too large, required critical optical alignments, used far too much electrical power, and were insufficiently rugged for use under the severe conditions of spacecraft launch and space flight. In contrast, the present instrument is compact, consumes relatively little power, and is rugged enough to withstand launch vibrations and space flight. In addition, this instrument is characterized by long-term stability, accuracy, and reliability. The diode laser in this spectrometer is operated in a wavelength-modulation mode. Different gases to be measured can be selected by changing modular laser units. The operation of the laser is controlled by customized, low-power electronic circuitry built around a digital signal-processor board. This customized circuitry also performs acquisition and analysis of data, controls communications, and manages errors.

  7. Tunable laser diode system for noninvasive blood glucose measurements.

    PubMed

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

    2005-12-01

    Optical sensing of glucose would allow more frequent monitoring and tighter glucose control for people with diabetes. The key to a successful optical noninvasive 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 low 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 microm wavelength range. The system is based on a 2.3 microm 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 present laser system and avenues for extending the tuning range beyond 400 nm. PMID:16390586

  8. Two photon absorption in high power broad area laser diodes

    NASA Astrophysics Data System (ADS)

    Dogan, Mehmet; Michael, Christopher P.; Zheng, Yan; Zhu, Lin; Jacob, Jonah H.

    2014-03-01

    Recent advances in thermal management and improvements in fabrication and facet passivation enabled extracting unprecedented optical powers from laser diodes (LDs). However, even in the absence of thermal roll-over or catastrophic optical damage (COD), the maximum achievable power is limited by optical non-linear effects. Due to its non-linear nature, two-photon absorption (TPA) becomes one of the dominant factors that limit efficient extraction of laser power from LDs. In this paper, theoretical and experimental analysis of TPA in high-power broad area laser diodes (BALD) is presented. A phenomenological optical extraction model that incorporates TPA explains the reduction in optical extraction efficiency at high intensities in BALD bars with 100μm-wide emitters. The model includes two contributions associated with TPA: the straightforward absorption of laser photons and the subsequent single photon absorption by the holes and electrons generated by the TPA process. TPA is a fundamental limitation since it is inherent to the LD semiconductor material. Therefore scaling the LDs to high power requires designs that reduce the optical intensity by increasing the mode size.

  9. Development of diode laser-ignited pyrotechnic and explosive components

    SciTech Connect

    Jungst, R.G.; Salas, F.J.; Watkins, R.D.; Kovacic, L.

    1990-01-01

    Studies are described which have led to the development of prototype diode laser-ignited pyrotechnic and explosive devices. These are of interest because they eliminate some concerns associated with ignition from hot wires such as conductance after firing, sensitivity to electromagnetic radiation and electrostatic discharge, and bridgewire corrosion. The availability of high power diode lasers is a key feature for the success of this concept. A pyrotechnic, Ti/KClO{sub 4}, and the deflagration-to-detonation transition (DDT) explosive CP have been evaluated and found suitable for use in LDI components. Doping with materials such as carbon black to increase light absorption near 800 nm is a major factor in reducing the laser power required to ignite CP, but does not strongly affect the ignition of Ti/KClO{sub 4}. Other material and laser input parameters were also studied to determine their influence on ignition thresholds. Even though they contain different energetic materials, the energy-power relationship of these optical igniters was generally similar in shape to those of other thermal ignition devices such as stable and electric igniters. Prototype, hermetically sealed, optical headers have been fabricated, loaded, and test fired with CP and Ti/KClO{sub 4}. Glass to metal sealing technology has been developed to insert sapphire windows or optical fiber segments in these fixtures. Devices containing fiber segments demonstrated superior performance in threshold tests. 8 refs., 12 figs., 3 tabs.

  10. Diode laser overtone spectroscopy of atmospheric trace species

    SciTech Connect

    Lucchesini, A.; Pelliccia, D.; Longo, I.; Gabbanini, C.; Gozzini, S.

    1994-12-31

    This work is based on the use of diode lasers as spectroscopic sources for the observation and study of weak overtone bands of the NIR. The diode laser emission wavelength can be scanned around a gas resonance by sweeping its injection current, permitting a direct observation of an absorption line-shape. The resolution is limited principally by the effective laser linewidth, generally {approx}20 MHz in free running mode. The signal-to-noise ratio is increased by using the frequency modulation technique, and the excess laser amplitude 1/f noise is reduced by working at high frequencies. Since detectors operating at high frequencies are expensive and less sensitive, a good compromise is the two-tone frequency modulation technique, which uses two close high frequencies and collects the beat signal at lower frequency. Pressure broadening coefficients have been measured for some acetylene and ammonia absorption lines in the 790 nm bands and new lines have been observed. Pressure shift of two acetylene lines have been examined. It is shown that this spectroscopic apparatus can extract very weak signals from the background and can be a good choice when the space occupied by the spectrometer needs to be restricted into small volumes.

  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. Perovskite Materials for Light-Emitting Diodes and Lasers.

    PubMed

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices.

  13. Perovskite Materials for Light-Emitting Diodes and Lasers.

    PubMed

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. PMID:27214091

  14. Narrow line diode laser stacks for DPAL pumping

    NASA Astrophysics Data System (ADS)

    Koenning, Tobias; Irwin, David; Stapleton, Dean; Pandey, Rajiv; Guiney, Tina; Patterson, Steve

    2014-02-01

    Diode pumped alkali metal vapor lasers (DPALs) offer the promise of scalability to very high average power levels while maintaining excellent beam quality, making them an attractive candidate for future defense applications. A variety of gain media are used and each requires a different pump wavelength: near 852nm for cesium, 780nm for rubidium, 766nm for potassium, and 670nm for lithium atoms. The biggest challenge in pumping these materials efficiently is the narrow gain media absorption band of approximately 0.01nm. Typical high power diode lasers achieve spectral widths around 3nm (FWHM) in the near infrared spectrum. With state of the art locking techniques, either internal to the cavity or externally mounted gratings, the spectral width can typically be reduced to 0.5nm to 1nm for kW-class, high power stacks. More narrow spectral width has been achieved at lower power levels. The diode's inherent wavelength drift over operating temperature and output power is largely, but not completely, eliminated. However, standard locking techniques cannot achieve the required accuracy on the location of the spectral output or the spectral width for efficient DPAL pumping. Actively cooled diode laser stacks with continuous wave output power of up to 100W per 10mm bar at 780nm optimized for rubidium pumping will be presented. Custom designed external volume holographic gratings (VHGs) in conjunction with optimized chip material are used to narrow and stabilize the optical spectrum. Temperature tuning on a per-bar-level is used to overlap up to fifteen individual bar spectra into one narrow peak. At the same time, this tuning capability can be used to adjust the pump wavelength to match the absorption band of the active medium. A spectral width of <0.1nm for the entire stack is achieved at <1kW optical output power. Tuning of the peak wavelength is demonstrated for up to 0.15nm. The technology can easily be adapted to other diode laser wavelengths to pump different materials.

  15. 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%.

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

    PubMed

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

    2014-04-01

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

  17. Spatially resolved argon microplasma diagnostics by diode laser absorption

    SciTech Connect

    Miura, Naoto; Hopwood, Jeffrey

    2011-01-01

    Microplasmas were diagnosed by spatially resolved diode laser absorption using the Ar 801.4 nm transition (1s{sub 5}-2p{sub 8}). A 900 MHz microstrip split ring resonator was used to excite the microplasma which was operated between 100-760 Torr (13-101 kPa). The gas temperatures and the Ar 1s{sub 5} line-integrated densities were obtained from the atomic absorption lineshape. Spatially resolved data were obtained by focusing the laser to a 30 {mu}m spot and translating the laser path through the plasma with an xyz microdrive. At 1 atm, the microplasma has a warm core (850 K) that spans 0.2 mm and a steep gradient to room temperature at the edge of the discharge. At lower pressure, the gas temperature decreases and the spatial profiles become more diffuse.

  18. Coherent communication link using diode-pumped lasers

    NASA Technical Reports Server (NTRS)

    Kane, Thomas J.; Wallace, Richard W.

    1989-01-01

    Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators.

  19. 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.

  20. 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.

  1. 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.

  2. Diode-Pumped Mode-Locked LiSAF Laser

    SciTech Connect

    1996-02-01

    Under this contract we have developed Cr{sup 3+}:LiSrAlF{sub 6} (Cr:LiSAF, LiSAF) mode-locked lasers suitable for generation of polarized electrons for CEBAF. As 670 nm is an excellent wavelength for optical pumping of Cr:LiSAF, we have used a LIGHTWAVE developed 670 nm diode pump module that combines the output of ten diode lasers and yields approximately 2 Watts of optical power. By the use of a diffraction limited pump beam however, it is possible to maintain a small mode size through the length of the crystal and hence extract more power from Cr:LiSAF laser. For this purpose we have developed a 1 Watt, red 660nm laser (LIGHTWAVE model 240R) which serves as an ideal pump for Cr:LiSAF and is a potential replacement of costly and less robust krypton laser. This new system is to compliment LIGHTWAVE Series 240, and is currently being considered for commercialization. Partially developed under this contract is LIGHTWAVEs product model 240 which has already been in our production lines for a few months and is commercially available. This laser produces 2 Watts of output at 532 nm using some of the same technology developed for production of the 660nm red system. It is a potential replacement for argon ion lasers and has better current and cooling requirements and is an excellent pump source for Ti:Al{sub 2}O{sub 3}. Also, as a direct result of this contract we now have the capability of commercially developing a mode-locked 100MHz Cr:LiSAF system. Such a laser could be added to our 100 MHz LIGHTWAVE Series 131. The Series 131 lasers provide pico second pulses and were originally developed under another DOE SBIR. Both models of LIGHTWAVE Series 240 lasers, the fiber coupled pump module and the 100MHz LiSAF laser of Series 131 have been partially developed under this contract, and are commercially competitive products.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  4. High power diode laser stack development using gold-tin bonding technology

    NASA Astrophysics Data System (ADS)

    Hou, Dong; Wang, Jingwei; Zhang, Pu; Cai, Lei; Dai, Ye; Li, Yingjie; Liu, Xingsheng

    2015-02-01

    High power diode lasers have increased application in many fields. In this work, a sophisticated high power and high performance conduction cooled diode laser stack has been developed for long pulse duration and high duty cycle using gold-tin (AuSn) bonding technology. The transient thermal behavior and optical simulation of the laser diode stack module are investigated to optimize the laser device structure. CTE-matched submount and AuSn hard solder are used for bonding the laser diode bar to achieve higher reliability and longer lifetime. Guided by the numerical simulation and analytical results, conduction cooled diode laser stack with high power, long pulse duration and high duty cycle is fabricated and characterized. Compared with the conventional indium bonding technology, the new design is a promising approach to obtain improved performance with high reliability and long lifetime.

  5. 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.

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

    PubMed Central

    Umberto, Romeo; Claudia, Russo; Gaspare, Palaia; Gianluca, Tenore; Alessandro, Del Vecchio

    2012-01-01

    Introduction. Dentine hypersensitivity (DH) is characterized by pain after stimuli that usually provoke no symptoms. This study compared the effectiveness of GaAlAs diode laser alone and with topical sodium fluoride gel (NaF). Materials and Methods. The study was conducted on 10 patients (8 F/2 M, age 25–60) and 115 teeth with DH assessed by air and tactile stimuli measured by Numeric Rating Scale (NRS). Teeth were randomly divided into G1 (34 teeth) treated by 1.25% NaF; G2 (33 teeth) lased at 0.5 W PW (T on 100 m and T off 100 ms), fluence 62.2 J/cm2 in defocused mode with a 320 μ fiber. Each tooth received three 1′ applications; G3 (48 teeth) received NaF gel plus laser at same G2 parameters. NRS was checked at each control. Results. Significant pain reduction was showed. The NRS reduction percentages were calculated, and there was a concrete decrease of DH above all in G3 than G2 and G1. Conclusion. Diode laser is a useful device for DH treatment if used alone and mainly if used with NaF gel. PMID:22792109

  8. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode.

    PubMed

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus; Shen, Yuxin; Vanderheiden, Sylvia; Valouch, Sebastian; Vannahme, Christoph; Bräse, Stefan; Mappes, Timo; Lemmer, Uli

    2012-03-12

    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources.

  9. Laser diode end-pumped ND:YAG laser. Memorandum report

    SciTech Connect

    Elder, I.F.

    1992-01-01

    100 Hz operation of a Nd:YAG laser longitudinally pumped by a 1 W peak power quasi-cw laser diode was investigated theoretically and experimentally. An optical-to-optical slope efficiency of 33%, indicating a wall-plug efficiency of 7%, was exhibited, but the threshold optical power of 330 mW was high due to poor antireflection coatings on the laser rod giving a round-trip intracavity loss of 3.1 %. The 1.064 micrometer output was observed to be diffraction-limited. The theoretical modelling of the laser's input/ output characteristics agreed well with the experimentally obtained results.

  10. Laser diode pumped high efficiency Yb:YAG crystalline fiber waveguide lasers

    NASA Astrophysics Data System (ADS)

    Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

    2015-02-01

    Single-clad and double-clad Yb:YAG crystalline fiber waveguides (CFWs) have been prepared with Adhesive-Free Bonding (AFB®) technology. By using a fiber coupled laser diode as pump source, a single-mode laser with near diffraction limited beam quality M2=1.02 has been demonstrated in a double-clad CFW. The laser output power and efficiency are 13.2 W and 34%, respectively. In a single-clad CFW, core pumping was used. The laser output has top-hat beam profile. An output power of 28 W and a slope efficiency of 78% have been achieved respectively.

  11. Edge-emitting diode lasers with narrow circular beam output

    NASA Astrophysics Data System (ADS)

    Wang, Lijie; Tong, Cunzhu; Zeng, Yugang; Ning, Yongqiang; Wang, Lijun

    2015-05-01

    We report near circular beam output from 808 nm edge-emitting diode lasers based on Bragg reflection waveguide design. Increasing quantum well number combined with reducing defect layer index and thickness was used to achieve high power output and extremely low vertical far field divergence. The TQW-BRLs achieve the lowest vertical divergence of 4.91° (full width at half maximum) and 9.8° (95% power). The maximum power of 4.6 W was achieved in the mounted DQW-BRL device under continuous-wave operation, being limited by thermal rollover.

  12. Asymmetrical prism for beam shaping of laser diode stacks.

    PubMed

    Zeng, Xiaodong; Cao, Changqing; An, Yuying

    2005-09-10

    A beam-shaping scheme for a laser diode stack to obtain a flattop output intensity profile is proposed. The shaping element consists of an asymmetrical glass prism. The large divergence-angle compression in the direction perpendicular to the junction plane and the small divergence-angle expansion in the parallel direction are performed simultaneously by a single shaping element. The transformation characteristics are presented, and the optimization performance is investigated based on the ray-tracing method. Analysis shows that a flattop intensity profile can be obtained. This beam-shaping system can be fabricated easily and has a large alignment tolerance.

  13. 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.

  14. Diode-laser frequency stabilization based on the resonant Faraday effect

    NASA Technical Reports Server (NTRS)

    Wanninger, P.; Valdez, E. C.; Shay, T. M.

    1992-01-01

    The authors present the results of a method for frequency stabilizing laser diodes based on the resonant Faraday effects. A Faraday cell in conjunction with a polarizer crossed with respect to the polarization of the laser diode comprises the intracavity frequency selective element. In this arrangement, a laser pull-in range of 9 A was measured, and the laser operated at a single frequency with a linewidth less than 6 MHz.

  15. Study on frequency control method for DBR laser diode based on FPGA

    NASA Astrophysics Data System (ADS)

    Hao, Jiepeng; Hong, Jintao; Chen, Linlin; Lei, Guanqun; Zhou, Binquan

    2015-10-01

    In recent years, the distributed Bragg reflector (DBR) laser diode (LD) has advantages of its small size, high efficiency, low power consumption and so on, so it has been widely used in precision measurement, optical information processing, quantum research and other fields. There is a strict requirement for the output frequency of the DBR laser diode in precision measurement technology. Therefore, controlling the frequency of the laser accurately is of great significance for precision measurement. Currently, there are a lot of frequency control scheme for laser diode, mainly through the external system to stabilize the frequency of laser diode, the drawback of which is that it is not conducive to system integration. Therefore, this paper proposes a method based on FPGA for controlling the output frequency of the laser diode. The main purpose of the control is to study the frequency characteristics of the laser diode. In this paper, the FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. At the same time, the control algorithm is programmed into the FPGA device, which can maximize the operating speed of control system. For different frequency of the laser, it is only required to modify the control parameters simply, which can be realized the steady control of the light source. Through the test, near the operating temperature of the laser diode, temperature stability is better than +/-0.01°C. As a result, the laser frequency stability can be controlled to 0.1%.

  16. 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. ...

  17. Compression of picosecond pulses from diode lasers using a modified grating-pair compressor.

    PubMed

    Kuznetsov, M; Wiesenfeld, J M; Radzihovsky, L R

    1990-02-01

    Optical pulses from gain-switched diode lasers were compressed using a grating-pair compressor containing an internal telescope. Original pulses of 20-30 psec were compressed to 5-7 psec, with the largest compression factor ~5. Diode-laser pulse compression is well modeled by transmission of Gaussian pulses with excess bandwidth through a dispersive system. PMID:19759750

  18. Tunable diode laser heterodyne radiometer measurement of atmospheric absorption of solar radiation

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Copeland, G. E.

    1980-01-01

    A tunable infrared heterodyne radiometer (TIHR) which uses a diode laser as the local oscillator is described as well as methods for the evaluation of the excess noise characteristics of the tunable diode laser. Preliminary atmospheric absorption data taken with the TIHR are presented and show the capability of the TIHR for making the highest resolution atmospheric measurements to date.

  19. LASER BIOLOGY AND MEDICINE: Medical instruments based on high-power diode and fibre lasers

    NASA Astrophysics Data System (ADS)

    Gapontsev, V. P.; Minaev, V. P.; Savin, V. I.; Samartsev, I. E.

    2002-11-01

    The characteristics and possible applications of scalpels based on diode and fibre lasers emitting at 0.97, 1.06, 1.56, and 1.9 μm, which are produced and developed by the IRE-Polyus Co., are presented. The advantages of such devices and the possibilities for increasing their output power and extending their spectral range are shown.

  20. Effects of neutron fluence on the operating characteristics of diode lasers used in atomic frequency standards

    NASA Astrophysics Data System (ADS)

    Frueholz, R. P.; Camparo, J. C.; Delcamp, S. B.; Barnes, C. E.

    1990-08-01

    One of the next major advances in rubidium and cesium atomic clock technology will center on the use of diode lasers for optical pumping. The atomic clocks used on board satellites have the potential to interact with various forms of radiation that are not present in the laboratory environment, and the effects of this radiation on the laser's operating characteristics relevant to clock applications are not well known. The effects were studied of neutron fluence on the operating characteristics of Mitsubishi Transverse Junction Stripe (TJS) AlGaAs diode lasers. Different models of the TJS diode laser produce optical radiation in both the 780 and 850 nm range, appropriate for optical pumping in rubidium and cesium atomic clocks, respectively. In this phase, a set of TJS diode lasers was exposed to a neutron fluence of 2 x 1012 n/sq cm, and four laser characteristics were examined after each exposure. The laser's light output versus injection current and single mode linewidth versus output power both influence the efficiency of optical pumping and hence the atomic clock's signal to noise ratio. The laser's single mode wavelength versus injection current (laser tuning) was also measured. Since the diode laser must remain tuned to the appropriate atomic transition, any degradation in the ability to tune the laser will impact atomic clock reliability. Finally, the diode laser's gain curve was studied at several injection currents below threshold.

  1. 635nm diode laser biostimulation on cutaneous wounds

    NASA Astrophysics Data System (ADS)

    Solmaz, Hakan; Gülsoy, Murat; Ülgen, Yekta

    2014-05-01

    Biostimulation is still a controversial subject in wound healing studies. The effect of laser depends of not only laser parameters applied but also the physiological state of the target tissue. The aim of this project is to investigate the biostimulation effects of 635nm laser irradiation on the healing processes of cutaneous wounds by means of morphological and histological examinations. 3-4 months old male Wistar Albino rats weighing 330 to 350 gr were used throughout this study. Low-level laser therapy was applied through local irradiation of red light on open skin excision wounds of 5mm in diameter prepared via punch biopsy. Each animal had three identical wounds on their right dorsal part, at which two of them were irradiated with continuous diode laser of 635nm in wavelength, 30mW of power output and two different energy densities of 1 J/cm2 and 3 J/cm2. The third wound was kept as control group and had no irradiation. In order to find out the biostimulation consequences during each step of wound healing, which are inflammation, proliferation and remodeling, wound tissues removed at days 3, 7, 10 and 14 following the laser irradiation are morphologically examined and than prepared for histological examination. Fragments of skin including the margin and neighboring healthy tissue were embedded in paraffin and 6 to 9 um thick sections cut are stained with hematoxylin and eosin. Histological examinations show that 635nm laser irradiation accelerated the healing process of cutaneous wounds while considering the changes of tissue morphology, inflammatory reaction, proliferation of newly formed fibroblasts and formation and deposition of collagen fibers. The data obtained gives rise to examine the effects of two distinct power densities of low-level laser irradiation and compare both with the non-treatment groups at different stages of healing process.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  3. 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.

  4. Side diode pumped ultra-compact Er:glass laser

    NASA Astrophysics Data System (ADS)

    Vitkin, Vladimir V.; Polyakov, Vadim M.; Kharitonov, Artem A.; Buchenkov, Vyacheslav A.; Rodionov, Andrey Y.

    2015-07-01

    We demonstrate side pumped ultra-compact Q-switched Er:glass laser for rangefinding with 1.4 mJ energy at 1.54 um. Laser diode with 75 W power and 5 ms pulse duration was used. Active medium was enveloped with diffuse reflector. Output pulse energy in free-running mode was 27 mJ with a slope efficiency of 12%. Transparent glass-ceramics containing Co2+:MgAl2O4 nanocrystals were used as a passive gate to ensure Q-switching in an operation temperature range and transverse mode selection. The Q-switch mode had steady operation at 1 Hz repetition rate with thermal effects playing no visible role.

  5. 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.

  6. Gain lever characterization in monolithically integrated diode lasers

    NASA Astrophysics Data System (ADS)

    Pocha, Michael; Bond, Tiziana; Welty, Rebecca; Vernon, Stephen; Kallman, Jeffrey; Behymer, Elaine

    2005-04-01

    Gain Lever, an effect for enhancing amplitude modulation (AM) efficiency in multisection laser diodes1, has been characterized in InGaAs DQW edge emitting lasers that are integrated with passive waveguides. Specifically designed structures which give a range of split ratios from 1:1 to 9:1 have been fabricated and measured to fully characterize the parameter space for operation in the gain lever mode. Additionally the experimental results are compared to a hybrid 3-D simulation involving effective index method (EIM) reduction to 2-D. Gains greater than 6 dB in the AM efficiency can be achieved within the appropriate operating range, but this gain drops rapidly as the parameter range is exceeded. High speed RF modulation with significant gain is, in principle, possible if proper biasing and modulation conditions are used. This phenomenon can also be useful for high-speed digital information transmission.

  7. 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.

  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. Combining femtosecond laser ablation and diode laser welding in lamellar and endothelial corneal transplants

    NASA Astrophysics Data System (ADS)

    Pini, Roberto; Rossi, Francesca; Matteini, Paolo; Ratto, Fulvio; Menabuoni, Luca; Lenzetti, Ivo; Yoo, Sonia H.; Parel, Jean-Marie

    2008-02-01

    Based on our previous clinical experiences in minimally invasive diode laser-induced welding of corneal tissue in penetrating keratoplasty (PK), i.e. full-thickness transplant of the cornea, we combined this technique with the use of a femtosecond laser for applications in lamellar (LK) and endothelial (EK) keratoplasty. In LK, the femtosecond laser was used to prepare donor button and recipient corneal bed; the wound edges were stained with a water solution of Indocyanine Green (ICG) and then irradiated with a diode laser emitting in CW mode to induce stromal welding. Intraoperatory observations and follow-up results up to 6 months indicated the formation of a smooth stromal interface, total absence of edema as well as inflammation, and reduction of post-operative astigmatism, as compared with conventional suturing procedures. In EK the femtosecond laser was used for the preparation of a 100 μm thick, 8.5mm diameter donor corneal endothelium flap. The flap stromal side was stained with ICG. After stripping the recipient Descemet's membrane and endothelium, the donor flap was positioned in the anterior chamber on the inner face of the cornea by an air bubble and secured to the recipient cornea by diode laser pulses delivered by means of a fiberoptic contact probe introduced in the anterior chamber, which produced welding spots of 200 μm diameter. Femtosecond laser sculpturing of the donor cornea provided lamellar and endothelial flaps of preset and constant thickness. Diode laserinduced welding showed a unique potential to permanently secure the donor flap in place, avoiding postoperative displacement and inflammation reaction.

  10. Gas analysis of human exhalation by tunable diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Stepanov, Eugene V.; Moskalenko, Konstantin L.

    1993-02-01

    Results of the application of a tunable diode laser (TDL) to determining the trace gas components of human exhalation are presented. The analyzer is specially developed to measure both carbon oxides (CO and CO2) in expired air. A few results illuminating possible applications of TDLs in high-sensitivity medical diagnostics have been obtained. For nonsmokers, expired concentrations of CO are slightly higher than those in inhaled air. The specific surplus value seems to be independent of the ambient atmospheric CO content. The surplus CO content increases by more than an order of magnitude just after intensive exercises, e.g., jogging. For smokers, the pharmacokinetic of abundant CO removal from the organism could be investigated by this technique, which provides quick and reliable measurements of smoking status. Breath-holding synchronous measurements of CO and CO2 in exhalation demonstrate behavior that is different with breath-holding time. The method seems useful for the investigation of phenomena such as molecular pulmonary diffusion through the alveolar-capillary membrane and an organism's adaptation to oxygen shortage. Prospects for the development and application of diode laser spectroscopy to trace gas analysis in medicine are also discussed.

  11. Multilayer optical data storage by fluorescence modulation using a CW laser

    NASA Astrophysics Data System (ADS)

    Singer, Kenneth D.; Christenson, Cory W.; Saini, Anuj; Ryan, Christopher J.; Mirletz, Heather; Shiyanovskaya, Irina; Yin, Kezhen; Baer, Eric

    2015-08-01

    Optical data storage has been widely used in certain consumer applications owing to its passive and robust nature, but has failed to keep with larger industry data storage needs due to the lack of capacity. Many alternatives have been proposed and developed, such as 3D data storage using two-photon absorption that require complex and dangerous laser systems to localize the bits. In this paper, we present a method for localizing bits using a CW 405nm laser diode, in a multilayered polymer film. Data is stored by photobleaching a fluorescent dye, and the response of the material is nonlinear, despite the CW laser and absorption in the visible region. This is achieved using sub-μs pulses from the laser initiating a photothermal effect. This writing method, along with the inexpensive roll-to-roll method for making the disc, will allow for terabyte-scale optical discs using conventional commercial optics and lasers.

  12. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, Raymond J.; Benett, William J.; Mills, Steven T.

    1997-01-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

  13. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, R.J.; Benett, W.J.; Mills, S.T.

    1997-04-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a ``rack and stack`` configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber. 3 figs.

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

    NASA Astrophysics Data System (ADS)

    Li, Lin

    2000-10-01

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

  15. Beam shaping design for compact and high-brightness fiber-coupled laser-diode system.

    PubMed

    Yu, Junhong; Guo, Linui; Wu, Hualing; Wang, Zhao; Tan, Hao; Gao, Songxin; Wu, Deyong; Zhang, Kai

    2015-06-20

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. A compact and high-brightness fiber-coupled system has been designed based on a significant beam shaping method. The laser-diode stack consists of eight mini-bars and is effectively coupled into a standard 100 μm core diameter and NA=0.22 fiber. The simulative result indicates that the module will have an output power over 440 W. Using this technique, compactness and high-brightness production of a fiber-coupled laser-diode module is possible.

  16. Hydrazine Detection with a Tunable Diode Laser Spectrometer

    NASA Technical Reports Server (NTRS)

    Houseman, John; Webster, C. R.; May, R. D.; Anderson, M. S.; Margolis, J. S.; Jackson, Julie R.; Brown, Pamela R.

    1999-01-01

    Several instruments have been developed to measure low concentrations of hydrazine but none completely meet the sensitivity requirements while satisfying additional criteria such as quick response, stable calibration, interference free operation, online operation, reasonable cost, etc. A brief review is presented of the current technology including the electrochemical cell, the ion mobility spectrometer, the mass spectrometer, and the gas chromatograph. A review of the advantages and disadvantages of these instruments are presented here. The review also includes commercially unavailable technology such as the electronic nose and the Tunable Diode Laser (TDL) IR Spectrometer. It was found that the TDL could meet the majority of these criteria including fast response, minimum maintenance, portability, and reasonable cost. An experiment was conducted to demonstrate the feasibility of such a system using an existing (non-portable) instrument. A lead-salt tunable diode laser, cooled to 85 degrees Kelvin was used to record direct absorption and second-derivative spectra of Hydrazine at several pressures to study the sensitivity to low levels of Hydrazine. Spectra of NH3 and CO2 were used for wavelength identification of the scanned region. With a pathlength of 80 m, detection sensitivities of about 1 ppb were achieved for hydrazine in dry nitrogen at a cell pressure of 100 mbar. For spectroscopic detection of Hydrazine, spectral regions including strong Ammonia or Carbon Dioxide lines must be avoided. Strong Hydrazine absorption features were identified at 940/cm showing minimal contribution from Ammonia interferences as suitable candidates for Hydrazine gas detection. For the studies reported here, the particular laser diode could only cover the narrow regions near 962/cm and 965/cm where strong Ammonia interferences were expected. However, the high resolution (0.001/cm) of the TDL spectrometer allowed individual lines of Hydrazine to be identified away from

  17. Low-threshold short-cavity diode laser for a miniature atomic clock

    SciTech Connect

    Kargapol'tsev, Sergei V; Velichansky, Vladimir L; Vasil'ev, V V; Kobyakova, M Sh; Morozyuk, A V; Shiryaeva, N V; Konyaev, V P

    2009-06-30

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D{sub 1} line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers. (lasers)

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

    SciTech Connect

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

    1996-01-01

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

  19. Functional possibilities for forming different inverse population distributions in diode-side-pumped laser heads

    SciTech Connect

    Grechin, S G; Nikolaev, P P; Sharandin, E A

    2014-10-31

    The functional possibilities of diode-side-pumped laser heads of solid-state lasers for forming inverse population distributions of different types are analysed. The invariants determining the relationship between the laser head parameters upon scaling are found. The results of comparative experimental studies are presented. (lasers)

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

    PubMed

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

    2014-10-10

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

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

    PubMed

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

    2014-10-10

    Efficient and compact laser-diode end-pumped Nd:GGG simultaneous multiwavelength continuous-wave lasers at ∼1059, ∼1060 and ∼1062  nm were first demonstrated in a free-running 30 mm plano-concave laser cavity. The maximum output power was up to 3.92 W with a slope efficiency of about 53.6% with respect to the absorbed pump power. By inserting a 0.1 mm optical glass plate acting as a Fabry-Pérot etalon, a single-wavelength laser at ∼1067  nm with a maximum output power of 1.95 W and a slope efficiency of 28.5% can be obtained. Multiwavelength lasers, including those at ∼1054 or ∼1067  nm, were also achievable by suitably tilting the glass etalon. These simultaneous multiwavelength lasers provide a potential source for terahertz wave generation. PMID:25322387

  2. Interference comparator for laser diode wavelength and wavelength instability measurement.

    PubMed

    Dobosz, Marek; Kożuchowski, Mariusz

    2016-04-01

    Method and construction of a setup, which allows measuring the wavelength and wavelength instability of the light emitted by a laser diode (or a laser light source with a limited time coherence in general), is presented. The system is based on Twyman-Green interferometer configuration. Proportions of phases of the tested and reference laser's interference fringe obtained for a set optical path difference are a measure of the unknown wavelength. Optical path difference in interferometer is stabilized. The interferometric comparison is performed in vacuum chamber. The techniques of accurate fringe phase measurements are proposed. The obtained relative standard uncertainty of wavelength evaluation in the tested setup is about 2.5 ⋅ 10(-8). Uncertainty of wavelength instability measurement is an order of magnitude better. Measurement range of the current setup is from 500 nm to 650 nm. The proposed technique allows high accuracy wavelength measurement of middle or low coherence sources of light. In case of the enlarged and complex frequency distribution of the laser, the evaluated wavelength can act as the length master in interferometer for displacement measurement. PMID:27131662

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

    PubMed

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

    2013-12-15

    Pulsed lasing from optically pumped rare gas metastable atoms (Ne, Ar, Kr, and Xe) has been demonstrated previously. The laser relies on a three-level scheme, which involves the (n+1)p[5/2](3) and (n+1)p[1/2](1) states from the np(5)(n+1)p electronic configuration and the metastable (n+1)s[3/2](2) level of the np(5)(n+1)s configuration (Racah notation). Population inversions were achieved using relaxation from ((n+1)p[5/2](3) to (n+1)p[1/2](1) induced by collisions with helium or argon at pressures near 1 atm. Pulsed lasing was easily achieved using the high instantaneous pump intensities provided by a pulsed optical parametric oscillator excitation laser. In the present study we examine the potential for the development of a continuous wave (CW) optically pumped Ar laser. We report lasing of the 4p[1/2](1)→4s[3/2](2) (912.547 nm) transition following CW diode laser excitation of the 4p[5/2](3)←4s[3/2](2) line (811.754 nm). A pulsed discharge was used to generate Ar 4s[3/2](2), and the time-resolved lasing kinetics provide insights concerning the radiative and collisional relaxation processes. PMID:24343016

  4. 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.

  5. Interference comparator for laser diode wavelength and wavelength instability measurement

    NASA Astrophysics Data System (ADS)

    Dobosz, Marek; KoŻuchowski, Mariusz

    2016-04-01

    Method and construction of a setup, which allows measuring the wavelength and wavelength instability of the light emitted by a laser diode (or a laser light source with a limited time coherence in general), is presented. The system is based on Twyman-Green interferometer configuration. Proportions of phases of the tested and reference laser's interference fringe obtained for a set optical path difference are a measure of the unknown wavelength. Optical path difference in interferometer is stabilized. The interferometric comparison is performed in vacuum chamber. The techniques of accurate fringe phase measurements are proposed. The obtained relative standard uncertainty of wavelength evaluation in the tested setup is about 2.5 ṡ 10-8. Uncertainty of wavelength instability measurement is an order of magnitude better. Measurement range of the current setup is from 500 nm to 650 nm. The proposed technique allows high accuracy wavelength measurement of middle or low coherence sources of light. In case of the enlarged and complex frequency distribution of the laser, the evaluated wavelength can act as the length master in interferometer for displacement measurement.

  6. Tunable diode laser systems from the UV to the NIR with up to 1 W

    NASA Astrophysics Data System (ADS)

    Kaenders, Wilhelm G.

    2000-03-01

    In the last fifteen years, initiated by the needs of the laser atom cooling community, grating-stabilized diode laser systems have emerged that cover a variety of scientific and increasingly, technical applications. The paper is intended to give an overview to the non-specialist on today's grating- tunable diode laser technology and its recent extensions, focusing on the two most frequently used designs. While the Metcalf-Littman approach is designated for far mode-hop free detuning, using mostly high quality anti-reflection-coated laser diodes, the Littrow set-up offers highest output power and most rigid operation at fixed wavelengths. The key advantage of the Littrow approach is its simplicity and the usage of standard commercial laser diodes without any special treatment. Reliable single frequency operation at about a tenth of the linewidth of the free-running laser diodes, mechanical tunability and active frequency control with diode lasers in the range from 390 to 1690 nm earn these diode laser systems a strong position in many research laboratories today. Using subsequent semiconductors the light can be amplified up to 1 Watt or frequency-doubled with an efficiency of more than 30% without loss of coherence.

  7. Multi-kW cw fiber oscillator pumped by wavelength stabilized fiber coupled diode lasers

    NASA Astrophysics Data System (ADS)

    Becker, Frank; Neumann, Benjamin; Winkelmann, Lutz; Belke, Steffen; Ruppik, Stefan; Hefter, Ulrich; Köhler, Bernd; Wolf, Paul; Biesenbach, Jens

    2013-02-01

    High power Yb doped fiber laser sources are beside CO2- and disk lasers one of the working horses of industrial laser applications. Due to their inherently given robustness, scalability and high efficiency, fiber laser sources are best suited to fulfill the requirements of modern industrial laser applications in terms of power and beam quality. Pumping Yb doped single-mode fiber lasers at 976nm is very efficient. Thus, high power levels can be realized avoiding limiting nonlinear effects like SRS. However the absorption band of Yb doped glass around 976nm is very narrow. Therefore, one has to consider the wavelength shift of the diode lasers used for pumping. The output spectrum of passively cooled diode lasers is mainly defined by the applied current and by the heat sink temperature. Furthermore the overall emission line width of a high power pump source is dominated by the large number of needed diode laser emitters, each producing an individual spectrum. Even though it is possible to operate multi-kW cw single-mode fiber lasers with free running diode laser pumps, wavelength stabilizing techniques for diode lasers (e.g. volume holographic gratings, VHG) can be utilized in future fiber laser sources to increase the output power level while keeping the energy consumption constant. To clarify the benefits of wavelength stabilized diode lasers with integrated VHG for wavelength locking the performance of a dual side pumped fiber oscillator is discussed in this article. For comparison, different pumping configurations consisting of stabilized and free-running diode lasers are presented.

  8. The Effect of Diode Laser With Different Parameters on Root Fracture During Irrigation Procedure.

    PubMed

    Karataş, Ertuğrul; Arslan, Hakan; Topçuoğlu, Hüseyin Sinan; Yılmaz, Cenk Burak; Yeter, Kübra Yesildal; Ayrancı, Leyla Benan

    2016-06-01

    The aim of this study is to compare the effect of a single diode laser application and agitation of EDTA with diode laser with different parameters at different time intervals on root fracture. Ninety mandibular incisors were instrumented except the negative control group. The specimens were divided randomly into 10 groups according to final irrigation procedure: (G1) non-instrumented; (G2) distilled water; (G3) 15% EDTA; (G4) ultrasonically agitated EDTA; (G5) single 1.5W/100 Hz Diode laser; (G6) single 3W/100 Hz Diode laser; (G7) 1.5W/100 Hz Diode laser agitation of EDTA for 20 s; (G8) 1.5W/100 Hz Diode laser agitation of EDTA for 40 s; (G9) 3W/100 Hz Diode laser agitation of EDTA for 20 s; and (G10) 3W/100 Hz Diode laser agitation of EDTA for 40 s. The specimens were filled, mounted in acrylic resin, and compression strength test was performed on each specimen. Statistical analysis was carried out using one way ANOVA and Tukey's post hoc tests (P = 0.05). The statistical analysis revealed that there were statistically significant differences among the groups (P < 0.05). Laser-agitated irrigation with a 3W/100 Hz Diode laser for both 20 s and 40 s decreased the fracture resistance of teeth.

  9. The Effect of Diode Laser With Different Parameters on Root Fracture During Irrigation Procedure.

    PubMed

    Karataş, Ertuğrul; Arslan, Hakan; Topçuoğlu, Hüseyin Sinan; Yılmaz, Cenk Burak; Yeter, Kübra Yesildal; Ayrancı, Leyla Benan

    2016-06-01

    The aim of this study is to compare the effect of a single diode laser application and agitation of EDTA with diode laser with different parameters at different time intervals on root fracture. Ninety mandibular incisors were instrumented except the negative control group. The specimens were divided randomly into 10 groups according to final irrigation procedure: (G1) non-instrumented; (G2) distilled water; (G3) 15% EDTA; (G4) ultrasonically agitated EDTA; (G5) single 1.5W/100 Hz Diode laser; (G6) single 3W/100 Hz Diode laser; (G7) 1.5W/100 Hz Diode laser agitation of EDTA for 20 s; (G8) 1.5W/100 Hz Diode laser agitation of EDTA for 40 s; (G9) 3W/100 Hz Diode laser agitation of EDTA for 20 s; and (G10) 3W/100 Hz Diode laser agitation of EDTA for 40 s. The specimens were filled, mounted in acrylic resin, and compression strength test was performed on each specimen. Statistical analysis was carried out using one way ANOVA and Tukey's post hoc tests (P = 0.05). The statistical analysis revealed that there were statistically significant differences among the groups (P < 0.05). Laser-agitated irrigation with a 3W/100 Hz Diode laser for both 20 s and 40 s decreased the fracture resistance of teeth. PMID:26582280

  10. An experimental study of low-frequency amplitude noise in a fibre Bragg grating laser diode

    SciTech Connect

    Zholnerov, V S; Ivanov, A V; Kurnosov, V D; Kurnosov, K V; Romantsevich, V I; Chernov, R V

    2013-09-30

    We have studied the amplitude noise in a fibre Bragg grating laser diode. It has been shown that discontinuities in noise characteristics correlate with those in the power – current and spectral characteristics of the laser diode, whereas the noise characteristics of the pump source have no such discontinuities. The highest noise level has been observed at pump currents corresponding to concurrent generation of two longitudinal modes. (lasers)

  11. Wide-aperture laser diode array in the external V-shaped cavity

    SciTech Connect

    Svetikov, V V; Nurligareev, D Kh

    2014-09-30

    The operation of a wide-aperture laser diode array with the radiation wavelength 980 nm in external V-shaped symmetric and asymmetric cavities is experimentally studied. The regimes of stable oscillation are studied as functions of the feedback beam direction. The spectra and the intensity distribution of radiation in the far zone are presented for the laser diode in symmetric and asymmetric cavities. Tuning of the radiation wavelength is demonstrated using the Littman geometry in the asymmetric cavity. (lasers)

  12. High-power, high-brightness, phase-locked broad-stripe diode lasers

    SciTech Connect

    Lindstrom, C.; Josefsson, A.; Franklin, G.; Milton, M.; Nyberg, C.

    1988-08-15

    A novel superlinear graded index separate confinement laser diode structure is proposed. Single stripe diode lasers with 210 ..mu..m emitting aperture generate 3.2 W cw, and 6.3 W quasi-cw of light-output power in a phase-locked operation. The catastrophic optical density (30 W/mm) obtained for these lasers is better than that reported for devices with nonabsorbing mirrors.

  13. Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Holm, Jesper; Pedersen, Christian; Andersen, Peter Eskil; Erbert, Götz; Sumpf, Bernd; Petersen, Paul Michael

    2005-12-26

    A high-power narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The external cavity laser system uses a new tapered amplifier with a super-large optical-cavity (SLOC) design that leads to improved performance of the external cavity diode lasers. The laser system is tunable over a 29 nm range centered at 802 nm. As high as 1.95 W output power is obtained at 803.84 nm, and an output power above 1.5 W is achieved from 793 to 812 nm at operating current of 3.0 A. The emission linewidth is below 0.004 nm and the beam quality factor M2 is below 1.3 over the 29 nm tunable range. As an example of application, the laser system is used as a pump source for the generation of 405 nm blue light by single-pass frequency doubling in a periodically poled KTiOPO4. An output power of 24 mW at 405 nm, corresponding to a conversion efficiency of 0.83%/W is attained. PMID:19503273

  14. Optical transfer cavity stabilization using current-modulated injection-locked diode lasers

    SciTech Connect

    Bohlouli-Zanjani, P.; Afrousheh, K.; Martin, J. D. D.

    2006-09-15

    It is demonstrated that rf current modulation of a frequency stabilized injection-locked diode laser allows the stabilization of an optical cavity to adjustable lengths, by variation of the rf frequency. This transfer cavity may be used to stabilize another laser at an arbitrary wavelength, in the absence of atomic or molecular transitions suitable for stabilization. Implementation involves equipment and techniques commonly used in laser cooling and trapping laboratories and does not require electro- or acousto-optic modulators. With this technique we stabilize a transfer cavity using a rf current-modulated diode laser which is injection locked to a 780 nm reference diode laser. The reference laser is stabilized using polarization spectroscopy in a Rb cell. A Ti:sapphire ring laser at 960 nm is locked to this transfer cavity and may be precisely scanned by varying the rf modulation frequency. We demonstrate the suitability of this system for the excitation of laser cooled Rb atoms to Rydberg states.

  15. Unveiling laser diode "fossil" and the dynamic analysis for heliotropic growth of catastrophic optical damage in high power laser diodes.

    PubMed

    Zhang, Qiang; Xiong, Yihan; An, Haiyan; Boucke, Konstantin; Treusch, Georg

    2016-01-01

    Taking advantage of robust facet passivation, we unveil a laser "fossil" buried within a broad area laser diode (LD) cavity when the LD was damaged by applying a high current. For the first time, novel physical phenomena have been observed at these dramatically elevated energy densities within the nanoscale LD waveguide. The observation of the laser "fossil" is interpreted with different mechanisms, including: the origination of bulk catastrophic optical damage (COD) due to locally high energy densities, heliotropic COD growth, solid-liquid-gas phase transformations, strong longitudinal phonon cooling effect on the molten COD wave front, and the formation of patterns due to laser lateral modes. For the first time the COD propagation is analyzed temporally by an acoustic phonon bouncing model and the COD velocity is extrapolated to be exponentially decreasing from more than 800 μm/μs to a few μm/μs within a 20 μs time period as the energy density dissipates. PMID:26740303

  16. Unveiling laser diode "fossil" and the dynamic analysis for heliotropic growth of catastrophic optical damage in high power laser diodes.

    PubMed

    Zhang, Qiang; Xiong, Yihan; An, Haiyan; Boucke, Konstantin; Treusch, Georg

    2016-01-07

    Taking advantage of robust facet passivation, we unveil a laser "fossil" buried within a broad area laser diode (LD) cavity when the LD was damaged by applying a high current. For the first time, novel physical phenomena have been observed at these dramatically elevated energy densities within the nanoscale LD waveguide. The observation of the laser "fossil" is interpreted with different mechanisms, including: the origination of bulk catastrophic optical damage (COD) due to locally high energy densities, heliotropic COD growth, solid-liquid-gas phase transformations, strong longitudinal phonon cooling effect on the molten COD wave front, and the formation of patterns due to laser lateral modes. For the first time the COD propagation is analyzed temporally by an acoustic phonon bouncing model and the COD velocity is extrapolated to be exponentially decreasing from more than 800 μm/μs to a few μm/μs within a 20 μs time period as the energy density dissipates.

  17. 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.

  18. Laser remelting of Ti6AL4V using high power diode laser

    NASA Astrophysics Data System (ADS)

    Amaya-Vázquez, M. R.; Sánchez-Amaya, J. M.; Boukha, Z.; El Amrani, K.; Botana, F. J.

    2012-04-01

    Titanium alloys present excellent mechanical and corrosion properties, being widely employed in different industries such as medical, aerospace, automotive, petrochemical, nuclear and power generation, etc. Ti6Al4V is the α-β alloy most employed in industry. The modification of its properties can be achieved with convectional heat treatments and/or with laser processing. Laser remelting (LR) is a technology applied to Ti6Al4V by other authors with excimer and Nd-Yag laser with pure argon shielding gas to prevent risk of oxidation. In the present contribution, laser remelting has been applied for the first time to Ti6Al4V with a high power diode laser (with pure argon as shielding gas). Results showed that remelted samples (with medium energy densities) have higher microhardness and better corrosion resistance than Ti6Al4V base metal.

  19. Effects of Different Polarization Strategies on Laser Cutting with Direct Diode Lasers

    NASA Astrophysics Data System (ADS)

    Rodrigues, G. Costa; Duflou, J. R.

    As Direct Diode Lasers are introduced as an emerging technology for laser cutting of metal sheets, new challenges arise. The relatively low beam quality remains a limitation to the maximum cutting speed. One way to balance this may be a strategic use of laser polarization in order to influence laser material interaction in the cutting kerf. In this paper the effects of cross-, linear-, radial- and azimuthal- laser beam polarization arrangements are studied with both Fusion and Flame cutting at an output power of approximately 750W. Different combinations of materials and thicknesses were cut and the maximum cutting speed and edge quality analyzed. It is found that at similar cutting edge quality, improvements in cutting speed can go up to 40% with an inert gas, such as Nitrogen, and up to 20% with a reactive gas, such as Oxygen, in agreement with analytical models for absorption previously developed by the authors.

  20. High-average-power diode-pumped Yb: YAG lasers

    SciTech Connect

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B

    1999-10-01

    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  1. Cryogenic ultra-high power infrared diode laser bars

    NASA Astrophysics Data System (ADS)

    Crump, Paul; Frevert, C.; Hösler, H.; Bugge, F.; Knigge, S.; Pittroff, W.; Erbert, G.; Tränkle, G.

    2014-02-01

    GaAs-based high power diode lasers are the most efficient source of optical energy, and are in wide use in industrial applications, either directly or as pump sources for other laser media. Increased output power per laser is required to enable new applications (increased optical power density) and to reduce cost (more output per component leads to lower cost in $/W). For example, laser bars in the 9xx nm wavelength range with the very highest power and efficiency are needed as pump sources for many high-energy-class solid-state laser systems. We here present latest performance progress using a novel design approach that leverages operation at temperatures below 0°C for increases in bar power and efficiency. We show experimentally that operation at -55°C increases conversion efficiency and suppresses thermal rollover, enabling peak quasi-continuous wave bar powers of Pout > 1.6 kW to be achieved (1.2 ms, 10 Hz), limited by the available current. The conversion efficiency at 1.6 kW is 53%. Following on from this demonstration work, the key open challenge is to develop designs that deliver higher efficiencies, targeting > 80% at 1.6 kW. We present an analysis of the limiting factors and show that low electrical resistance is crucial, meaning that long resonators and high fill factor are needed. We review also progress in epitaxial design developments that leverage low temperatures to enable both low resistance and high optical performance. Latest results will be presented, summarizing the impact on bar performance and options for further improvements to efficiency will also be reviewed.

  2. Aluminium surface treatment with ceramic phases using diode laser

    NASA Astrophysics Data System (ADS)

    Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

    2016-07-01

    Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

  3. Hardening and welding with high-power diode lasers

    NASA Astrophysics Data System (ADS)

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

    2000-03-01

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

  4. High peak power diode stacks for high energy lasers

    NASA Astrophysics Data System (ADS)

    Negoita, Viorel C.; Vethake, Thilo; Jiang, John; Roff, Robert; Shih, Ming; Duck, Richard; Bauer, Marc; Mite, Roberto; Boucke, Konstantin; Treusch, Georg

    2015-02-01

    High energy solid state lasers are being developed for fusion experiments and other research applications where high energy per pulse is required but the repetition rate is rather low, around 10Hz. We report our results on high peak power diode laser stacks used as optical pumps for these lasers. The stacks are based on 10 mm bars with 4 mm cavity length and 55% fill factor, with peak power exceeding 500 W per bar. These bars are stacked and mounted on a cooler which provides backside cooling and electrical insulation. Currently we mount 25 bars per cooler for a nominal peak power of 12.5 kW, but in principle the mounting scheme can be scaled to a different number of devices depending on the application. Pretesting of these bars before soldering on the cooler enables us to select devices with similar wavelength and thus we maintain tight control of the spectral width (FWHM less than 6 nm). Fine adjustments of the centroid wavelength can be done by means of temperature of the cooling fluid or bias current. The available wavelength range spans from 880 nm to 1000 nm, and the wavelength of the entire assembly of stacks can be controlled to within 0.5 nm of the target value, which makes these stacks suitable for pumping a variety of gain media. The devices are fast axis collimated, with over 95% power being collimated in 6 mrad (full angle). The slow axis divergence is 9° (full angle) for 95% power content.

  5. 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.

  6. Measurements of Trace Gases Using a Tunable Diode Laser

    NASA Technical Reports Server (NTRS)

    Jost, Hans-Juerg

    2005-01-01

    This report is the final report for "Measurements of Trace Gases Using a Tunable Diode Laser." The tasks outlined in the proposal are listed below with a brief comment. The publications and the conference presentations are listed. Finally, the important publications are attached. The Cooperative Agreement made possible a research effort to produce high- precision and high-accuracy in-situ measurements of carbon monoxide, methane and nitrous oxide on the WB-57 during the CRYSTAL-FACE and pre-AVE field campaigns and to analyze these measurements. These measurements of CO and CH4 were of utmost importance to studies of the radiative effects of clouds. Some important results of the CRYSTAL-FACE program were contained in two scientific papers (attached). This Cooperative Agreement allowed the participation of the Argus instrument in the program and the analysis of the data.

  7. Laser diode with thermal conducting, current confining film

    NASA Technical Reports Server (NTRS)

    Hawrylo, Frank Z. (Inventor)

    1980-01-01

    A laser diode formed of a rectangular parallelopiped body of single crystalline semiconductor material includes regions of opposite conductivity type indium phosphide extending to opposite surfaces of the body. Within the body is a PN junction at which light can be generated. A stripe of a conductive material is on the surface of the body to which the P type region extends and forms an ohmic contact with the P type region. The stripe is spaced from the side surfaces of the body and extends to the end surfaces of the body. A film of germanium is on the portions of the surface of the P type region which is not covered by the conductive stripe. The germanium film serves to conduct heat from the body and forms a blocking junction with the P type region so as to confine the current through the body, across the light generating PN junction, away from the side surfaces of the body.

  8. Oxygen detection using the laser diode absorption technique

    NASA Technical Reports Server (NTRS)

    Disimile, P. J.; Fox, C. W.

    1991-01-01

    Accurate measurement of the concentration and flow rate of gaseous oxygen is becoming of greater importance. The detection technique presented is based on the principal of light absorption by the Oxygen A-Band. Oxygen molecules have characteristics which attenuate radiation in the 759-770 nm wavelength range. With an ability to measure changes in the relative light transmission to less than 0.01 percent, a sensitive optical gas detection system was configured. This system is smaller in size and light in weight, has low energy requirements and has a rapid response time. In this research program, the application of temperature tuning laser diodes and their ability to be wavelength shifted to a selected absorption spectral peak has allowed concentrations as low as 1300 ppm to be detected.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  10. Linear laser diode arrays for improvement in optical disk recording

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.; Carlin, D. B.; Connolly, J. C.

    1990-01-01

    The development of individually addressable laser diode arrays for multitrack magneto-optic recorders for space stations is discussed. Three multi-element channeled substrate planar (CSP) arrays with output power greater than 30 mW with linear light vs current characteristics and stable single mode spectra were delivered to NASA. These devices have been used to demonstrate for the first time the simultaneous recording of eight data tracks on a 14-inch magneto-optic erasable disk. The yield of these devices is low, mainly due to non-uniformities inherent to the LPE growth that was used to fabricate them. The authors have recently developed the inverted CSP, based on the much more uniform MOCVD growth techniques, and have made low threshold quantum well arrays requiring about three times less current than the CSP to deliver 30 mW CW in a single spatial mode. The inverted CSP is very promising for use in space flight recorder applications.

  11. Electron microscopy of life-tested semiconductor laser diodes

    PubMed

    Vanzi; Bonfiglio; Magistrali; Salmini

    2000-06-01

    Electron Microscopy on life-tested 980 nm SL SQW InGaAs/AlGaAs laser diodes is able to find and analyze lattice defects responsible for the detected failures. Anyway, the origin and evolution of those defects remains questionable. Only the comparative analysis of life-test measurements, EBIC-FIB/TEM images, and charge-transport physics is able to point out a coherent framework for complete decoding of the failure kinetics. Minority-carrier diffusion and their enhanced recombination at defective lattice points are indicated, as the energy supply required for defect reaction and growth. The rules of charge diffusion drive both the reaction model, the interpretation of EBIC images and the expected electrical and optical effects. Strain release at the ultimate propagation of defects into the strained InGaAs quantum layer is then easily related to the final state of the failed devices.

  12. Pulsed diode laser-based monitor for singlet molecular oxygen

    PubMed Central

    Lee, Seonkyung; Zhu, Leyun; Minhaj, Ahmed M.; Hinds, Michael F.; Vu, Danthu H.; Rosen, David I.; Davis, Steven J.; Hasan, Tayyaba

    2010-01-01

    Photodynamic therapy (PDT) is a promising cancer treatment. PDT uses the affinity of photosensitizers to be selectively retained in malignant tumors. When tumors, pretreated with the photosensitizer, are irradiated with visible light, a photochemical reaction occurs and tumor cells are destroyed. Oxygen molecules in the metastable singlet delta state O2(1Δ) are believed to be the species that destroys cancerous cells during PDT. Monitoring singlet oxygen produced by PDT may lead to more precise and effective PDT treatments. Our approach uses a pulsed diode laser-based monitor with optical fibers and a fast data acquisition system to monitor singlet oxygen during PDT. We present results of in vitro singlet oxygen detection in solutions and in a rat prostate cancer cell line as well as PDT mechanism modeling. PMID:18601555

  13. Pulsed diode laser-based monitor for singlet molecular oxygen.

    PubMed

    Lee, Seonkyung; Zhu, Leyun; Minhaj, Ahmed M; Hinds, Michael F; Vu, Danthu H; Rosen, David I; Davis, Steven J; Hasan, Tayyaba

    2008-01-01

    Photodynamic therapy (PDT) is a promising cancer treatment. PDT uses the affinity of photosensitizers to be selectively retained in malignant tumors. When tumors, pretreated with the photosensitizer, are irradiated with visible light, a photochemical reaction occurs and tumor cells are destroyed. Oxygen molecules in the metastable singlet delta state O2(1Delta) are believed to be the species that destroys cancerous cells during PDT. Monitoring singlet oxygen produced by PDT may lead to more precise and effective PDT treatments. Our approach uses a pulsed diode laser-based monitor with optical fibers and a fast data acquisition system to monitor singlet oxygen during PDT. We present results of in vitro singlet oxygen detection in solutions and in a rat prostate cancer cell line as well as PDT mechanism modeling.

  14. Microgravity Diode Laser Spectroscopy Measurements in a Reacting Vortex Ring

    NASA Technical Reports Server (NTRS)

    Chen, Shin-Juh; Dahm, Werner J. A.; Silver, Joel A.; Piltch, Nancy D.; VanderWal, R. (Technical Monitor)

    2001-01-01

    The technique of Diode Laser Spectroscopy (DLS) with wavelength modulation is utilized to measure the concentration of methane in reacting vortex rings under microgravity conditions. From the measured concentration of methane, other major species such as water, carbon dioxide, nitrogen, and oxygen can be easily computed under the assumption of equilibrium chemistry with an iterative method called ITAC (Iterative Temperature with Assumed Chemistry). The conserved scalar approach in modelling the coupling between fluid dynamics and combustion is utilized to represent the unknown variables in terms of the mixture fraction and scalar dissipation rate in conjunction with ITAC. Post-processing of the DLS and the method used to compute the species concentration are discussed. From the flame luminosity results, ring circulation appears to increase the fuel consumption rate inside the reacting vortex ring and the flame height for cases with similar fuel volumes but different ring circulations. The concentrations of methane, water, and carbon dioxide agree well with available results from numerical simulations.

  15. Endogenous CO dynamics monitoring in breath by tunable diode laser

    NASA Astrophysics Data System (ADS)

    Kouznetsov, Andrian I.; Stepanov, Eugene V.; Shulagin, Yurii A.; Skrupskii, Vladimir A.

    1996-04-01

    High sensitive CO gas analyzer based on tunable diode laser (TDL) was used as a real time monitor of endogenous carbon monoxide in a set of breath physiology experiments. The measurements of the CO content dynamics in exhaled air with 10 ppb sensitivity were attended with detection of carbon dioxide and O2 in breath, lung ventilation parameters, heart rate and blood analysis using conventional techniques. Variations of endogenous CO in human breath caused by hyperoxia, hypoxia, hyperventilation as well as sport loading were studied in real time. Scattering of the CO variation time constants was observed for different tested persons. Possible reasons for this scattering related with the organisms' physiology peculiarities are discussed.

  16. Near-infrared transmittance pulse oximetry with laser diodes.

    PubMed

    Lopez Silva, Sonnia Maria; Dotor Castilla, Maria Luisa; Silveira Martin, Juan Pedro

    2003-07-01

    Pulse oximeters are widely used for noninvasive monitoring of oxygen saturation in arterial blood hemoglobin. We present a transmittance pulse oximetry system based on near-infrared (NIR) laser diodes (750 and 850 nm) for monitoring oxygen saturation of arterial blood hemoglobin. The pulse oximetry system is made up of the optical sensor, sensor electronics, and processing block. Also, we show experimental results obtained during the development of the whole NIR transmittance pulse oximetry system along with modifications in the sensor configuration, signal processing algorithm, and calibration procedure. Issues concerning wavelength selection and its implications for the improvement of the transmittance pulse oximetry technique are discussed. The results obtained demonstrate the proposed system's usefulness in monitoring a wide range of oxygen saturation levels.

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

    PubMed

    Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H P; Kordts, Arne; Kamel, Ayman N; Guo, Hairun; Geiselmann, Michael; Kippenberg, Tobias J

    2016-07-01

    Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers, which allows us to extend the measurement bandwidth to 37.4 THz (1355-1630 nm) at megahertz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy, and in particular it enables us to characterize the dispersion of integrated microresonators up to the 4th-order.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  19. Highly Reliable Operation of Red Laser Diodes for POF Data Links

    NASA Astrophysics Data System (ADS)

    Ohgoh, Tsuyoshi; Mukai, Atsushi; Mukaiyama, Akihiro; Asano, Hideki; Hayakawa, Toshiro

    Laser diodes for plastic optical fiber (POF) data links are required stable operation >100,000h at 60°C, 5mW and the transmission speed beyond 1Gbps. By optimizing crystal growth conditions and device structures, we have successfully fabricated highly reliable laser diodes with 1.25 Gbps transmission speed. The median lifetime for 5mW operation at 60°C was estimated to be more than 800,000h. These results indicate that 660 nm band laser diodes are very promising light sources for POF data links.

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

    PubMed

    Maeda, Y

    1994-01-10

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

  1. Influence of laser diode red beams on germination rate of tomato seeds

    NASA Astrophysics Data System (ADS)

    Niculita, P.; Danaila-Guidea, Silvana; Livadariu, Oana; Popa, M.; Ristici, M.; Ristici, Esofina

    2007-08-01

    Laser diodes are lighting devices in which the light is generated by stimulated emission rather than spontaneous emission, with high generation efficiency. A device using 20 red laser diodes is presented. Emission wavelengths are in the 650-670 nm range. Emission power for each laser diode is about 4 mW. This device is used to irradiate the tomato seeds with three different irradiating doses. There were three Petri vessels for each dose having 25 seeds each of them. Results show that the germination rate increases for irradiated seeds. The red light has a positive effect for vegetable cultivated in protected area.

  2. Remote sensing of atmospheric trace gases by diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Kan, Ruifeng; He, Yabai; He, Ying; Zhang, Yujun; Xie, Pinhua; liu, Wenqing

    2016-04-01

    Gaseous ammonia is the most abundant alkaline trace gas in the atmosphere. In order to study its role in acid deposition and aerosol formation, as well as its influence on the regional air quality and atmospheric visibility, several instruments has been developed based on TDLAS (Tunable Diode Laser Absorption Spectroscopy) techniques. In this paper, a long open path TDLAS system and a continuous-wave CRDS (Cavity-Ring down Spectroscopy) system are presented. The long open path system has been developed for NH3 in-situ monitoring by combining wavelength modulation with harmonic detection techniques to obtain the necessary detection sensitivity. The prototype instrument has been used to monitor atmospheric NH3 concentration at an urban site near Beijing National Stadium during Beijing Olympics in 2008, and recently used to measure the fluxes of NH3 from farm fields by flux-gradient method. The detection limit for ammonia is proved approximately 3ppb for a total path length of 456m. The continuous-wave, rapidly swept CRDS system has been developed for localized atmospheric sensing of trace gases at remote sites. Passive open-path optical sensor units could be coupled by optical fiber over distances of >1 km to a single transmitter/receiver console incorporating a photodetector and a swept-frequency diode laser tuned to molecule-specific near-infrared wavelengths. A noise-limited minimum detectable mixing ratio of ~11 ppbv is attained for ammonia at atmospheric pressure. The developed instruments are deployable in agricultural, industrial, and natural atmospheric environments.

  3. Noninvasive blood glucose measurement using multiple laser diodes

    NASA Astrophysics Data System (ADS)

    Ooi, E. T.; Zhang, X. Q.; Chen, J. H.; Soh, P. H.; Ng, K.; Yeo, J. H.

    2007-02-01

    In the event of diabetes clinicians have advocated that frequent monitoring of a diabetic's blood glucose level is the key to avoid future complications (kidney failure, blindness, amputations, premature death, etc.,) associated with the disease. While the test-strip glucose meters available in current consumer markets allow for frequent monitoring, a more convenient technique that is accurate, painless and sample-free is preferable in a diabetic's daily routine. This paper presents a non-invasive blood glucose measurement technique using diffuse reflectance near infrared (NIR) signals. This technique uses a set of laser diodes, each operating at fixed wavelengths in the first overtone region. The NIR signals from the laser diodes are channeled to the measurement site viz., the nail-bed by means of optical fibers. A series of in vivo experiments have been performed on eight normal human subjects using a standard Oral Glucose Tolerance Test (OGTT) protocol. The reflected NIR signals are inputs to a Partial Least Squares (PLS) algorithm for calibration and future predictions. The calibration models used are developed using in vivo datasets and are unique to a particular individual. The 1218 paired points collected from the eight test subjects plotted on the Clarke Error Grid, revealed that 87.3% of these points fall within the A zone while the remainder, within the B zone, both of which, are clinically accepted. The standard error of prediction was +/-13.14mg/dL for the best calibration model. A Bland-Altman analysis of the 1218 paired points yields a 76.3% confidence level for a measurement accuracy of +/-20mg/dL. These results demonstrate the initial potential of the technique for non-invasive blood glucose measurements in vivo.

  4. 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.

  5. Advances in high-power 9XXnm laser diodes for pumping fiber lasers

    NASA Astrophysics Data System (ADS)

    Skidmore, Jay; Peters, Matthew; Rossin, Victor; Guo, James; Xiao, Yan; Cheng, Jane; Shieh, Allen; Srinivasan, Raman; Singh, Jaspreet; Wei, Cailin; Duesterberg, Richard; Morehead, James J.; Zucker, Erik

    2016-03-01

    A multi-mode 9XXnm-wavelength laser diode was developed to optimize the divergence angle and reliable ex-facet power. Lasers diodes were assembled into a multi-emitter pump package that is fiber coupled via spatial and polarization multiplexing. The pump package has a 135μm diameter output fiber that leverages the same optical train and mechanical design qualified previously. Up to ~ 270W CW power at 22A is achieved at a case temperature ~ 30ºC. Power conversion efficiency is 60% (peak) that drops to 53% at 22A with little thermal roll over. Greater than 90% of the light is collected at < 0.12NA at 16A drive current that produces 3.0W/(mm-mr)2 radiance from the output fiber.

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

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

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

  7. Spin polarization of 87Rb atoms with ultranarrow linewidth diode laser: Numerical simulation

    NASA Astrophysics Data System (ADS)

    Wang, Z. G.; Jiang, Q. Y.; Zhan, X.; Chen, Y. D.; Luo, H.

    2016-08-01

    In order to polarize 87Rb 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.

  8. Effect of 405-nm high-intensity narrow-spectrum light on fibroblast-populated collagen lattices: an in vitro model of wound healing

    NASA Astrophysics Data System (ADS)

    McDonald, Richard; MacGregor, Scott J.; Anderson, John G.; Maclean, Michelle; Grant, M. Helen

    2011-04-01

    High-intensity narrow-spectrum (HINS) 405-nm light is a novel technology developed to address the significant problem of health-care associated infection. Its potential for wound-decontamination applications is assessed on mammalian cells and bacteria. The fibroblast-populated collagen lattice (FPCL) is used as an in vitro model of wound healing, and the effect of HINS light on contraction is examined. Effects on cell proliferation, morphological changes, and α-smooth muscle actin (α-SMA) expression are investigated. Bactericidal effects are assessed using the bacterium Staphylococcus epidermidis. Low doses of HINS light were found to have no significant inhibitory effects on FPCL contraction, cell proliferation, or α-SMA expression. Doses of up to 18 Jcm-2 had no significant inhibitory effects on FPCL cell numbers, and this dose was shown to cause almost complete inactivation of bacteria. These results show that HINS light has potential for disinfection applications without adversely influencing wound healing.

  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. Laser vaporization of extravasation type of mucocele of the lower lip with 940-nm diode laser.

    PubMed

    Agarwal, G; Mehra, A; Agarwal, A

    2013-01-01

    A 43-year-old male presented with an asymptomatic swelling of the lower labial mucosa. Examination revealed that the tip of maxillary canine was causing trauma on the affected side. A diagnosis of extravasation type of mucocele was established clinically. Vaporization of the mucocele was done with a 940-nm diode laser in contact mode. The lesion healed uneventfully and there has been no recurrence for 3 months. PMID:23965466

  11. Tunable frequency stabilized diode-laser-pumped Tm,Ho:YLiF4 laser at room temperature

    NASA Technical Reports Server (NTRS)

    Mcguckin, Brendan T.; Menzies, Robert T.; Esproles, Carlos

    1993-01-01

    A diode-laser-pumped single-frequency thulium holmium yttrium lithium fluoride laser that exhibits a closed-loop stability of a few megahertz and a continuous single-mode tuning range of 800 MHz is described. The laser output power is 25 mW, and is tunable over about 8/cm at 25 C.

  12. Diode-pumped alkali laser-bleached wave dynamics

    NASA Astrophysics Data System (ADS)

    Perram, Glen P.; Miller, Wooddy; Hurd, Ed

    2012-11-01

    A three level analytic model for optically pumped alkali metal vapor lasers is developed by considering the steady state rate equations for the longitudinally averaged number densities of the ground 2S 1/2 and first excited 2P3/2, and 2P1/2 states. The threshold pump intensity includes both the requirements to fully bleach the pump transition and exceed optical losses, typically about 200 Watts/cm2. Slope efficiency depends critically on the fraction of incident photons absorbed. For efficient operation, the collisional relaxation between the two upper levels should be fast to prevent bottle-necking. By assuming a statistical distribution between the upper two levels, the limiting analytic solution for the quasi-two level system is achieved. The highly saturated pump limit of the recently developed three-level model for Diode Pumped Alkali Lasers (DPAL) is also developed. The model is anchored to several recent laser demonstrations. A rubidium laser pumped on the 5 2S1/2 - 5 2P3/2 D2 transition by a pulsed dye laser at pump intensities exceeding 3.5 MW/cm2 (< 1000 times threshold) has been demonstrated. Output energies as high as 12 μJ/pulse are limited by the rate for collision relaxation of the pumped 2P3/2 state to the upper laser 2P1/2 state. More than 250 photons are available for every rubidium atom in the pumped volume during each pulse. For modest alkali atom and ethane spin-orbit relaxer concentrations, the gain medium can only process about 50 photons/atom during the 2 - 8 ns pump pulse. At 110° C and 550 Torr of ethane, the system is bottlenecked. The system efficiency based on absorbed photons approaches 36% even for these extreme pump conditions. Furthermore, at 320°C with 2500 torr of helium, a pulsed potassium laser with 1.15 MW/cm2 peak intensity and 9.3% slope efficiency has been demonstrated.

  13. 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.

  14. Ambient and laboratory measurements of ice nuclei and their biological faction with the Fast Ice Nuclei CHamber FINCH-HALO using the new 405nm Version of the BIO-IN Sensor

    NASA Astrophysics Data System (ADS)

    Bundke, U.; Nillius, B.; Bingemer, H.; Curtius, J.

    2012-04-01

    We have designed the BIO-IN detector as part of the ice nucleus counter FINCH (Fast Ice Nuclei CHamber counter) to distinguish activated Ice Nuclei (IN) ice crystals from water droplets (CCN) (Bundke et al. 2008) and their fraction of biological origin (Bundke 2010). The modified BIO-IN sensor illuminates an aerosol stream with a 405 nm laser, replacing a 365nm LED of the original BIO IN design. Particles will scatter the light and those of biological origin will show intrinsic fluorescence emissions by excitation of mainly Riboflavin, also known as vitamin B2. The incident laser light is circularly polarized by introducing a quarter-wave-plate. The circular depolarization ratio (p44/p11) of the scattering matrix is measured in the backward direction by two photomultipliers at 110° scattering angle using a combination of quarter-wave-plate and a beam splitting cube to analyze the two circular polarization components. The detection limit was lowered towards particle size of about 400nm diameter (non activated particles). It is now possible to calculate the activated fraction of IN of biological origin with respect to all biological particles measured with one detector. The performance of the sensor will be demonstrated showing the circular- depolarization properties of different test aerosol, dust samples, volcanic ashes as well as different biological particles. Measurements on the mountain Puy de Dôme of IN number concentration of ambient air, as well as measurements at the AIDA facility in Karlsruhe of the IN activation curves from different bacteria are shown. Acknowledgements: This work was supported by the German Research Foundation, Grant: BU 1432/3-2 BU 1432/4-1

  15. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  16. Low-Cost, Single-Frequency Sources for Spectroscopy Using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Duerksen, Gary L.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  17. Low-Cost, Single-Frequency Sources for Spectroscopy using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  18. Monitoring of catalyst performance in CO2 lasers using frequency modulation spectroscopy with diode lasers

    NASA Technical Reports Server (NTRS)

    Wang, Liang-Guo; Sachse, Glen

    1990-01-01

    Closed-cycle CO2 laser operation with removal of O2 and regeneration of CO2 can be achieved by catalytic CO-O2 recombination. Both parametric studies of the optimum catalyst formulation and long-term performance tests require on line monitoring of CO, O2 and CO2 concentrations. There are several existing methods for molecular oxygen detection. These methods are either intrusive (such as electrochemical method or mass spectrometry) or very expensive (such as CARS, UV laser absorption). Researchers demonstrated a high-sensitivity spectroscopic measurement of O2 using the two-tone frequency modulation spectroscopy (FMS) technique with a near infrared GaAlAs diode laser. Besides its inexpensive cost, fast response time, nonintrusive measurements and high sensitivity, this technique may also be used to differentiate between isotopes due to its high spectroscopic resolution. This frequency modulation spectroscopy technique could also be applied for the on-line monitoring of CO and CO2 using InGaAsP diode lasers operation in the 1.55 microns region and H2O in the 1.3 microns region. The existence of single mode optical fibers at the near infrared region makes it possible to combine FMS with optical fiber technology. Optical fiber FMS is particularly suitable for making point-measurements at one or more locations in the CO2 laser/catalyst system.

  19. 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.

  20. 954 nm Raman fiber laser with multimode laser diode pumping

    NASA Astrophysics Data System (ADS)

    Zlobina, E. A.; Kablukov, S. I.; Skvortsov, M. I.; Nemov, I. N.; Babin, S. A.

    2016-03-01

    CW Raman fiber laser emitting at 954 nm under direct pumping by a high-power multimode laser diode at 915 nm is demonstrated. A cavity of the laser is formed with 2.5 km-long multimode graded-index fiber and two mirrors: highly reflective fiber Bragg grating (FBG) at one side and normally cleaved fiber end at the other side. The laser generates low-index transverse modes at the Stokes wavelength with output power above 4 W at a slope efficiency above 40%. It is shown that utilization of a narrowband FBG mirror with low reflectivity instead of the cleaved fiber end with Fresnel reflection leads to stronger spectral mode selection, but the generated power is reduced in this case.

  1. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization.

  2. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization. PMID:27420499

  3. Time division multiplexed laser Doppler anemometry using pulsed laser diodes and optical fibers

    SciTech Connect

    Lockey, R.A.; Tatam, R.P.

    1995-12-31

    Laser Doppler anemometry (LDA) is a well established technique for non-invasive measurement of fluid flow, by measuring the frequency shift of light scattered by particles entrained in the flow. A time division multiplexed laser Doppler anemometer is reported, using a single high frequency pulsed laser diode as a source. Time division multiplexing requires a single detector channel, removing the need for multiple detectors and wavelength separation optics found in conventional CW laser Doppler systems. By incorporating optical fibers into the system to distribute the pulses into each channel and impose a delay between channels, the electronic requirements of such an instrument are reduced. Results for a two-dimensional system are presented, measured on a water-seeded air jet. Individual velocity components of up to 16 ms{sup {minus}1} and overall velocities of up to 20 ms{sup {minus}1} have been detected, but the potential range of the instrument is very much greater.

  4. AlGaAs laser diode FM spectrum: Phased array antenna application

    NASA Astrophysics Data System (ADS)

    Chamberland, Martin; Tetu, Michel

    Preliminary results are presented on the use of an AlGaAs laser diode to generate microwave signals suitable for application with phased array antennas. The relative intensity noise (RIN) was measured under various operating conditions to give an indication of the frequency response limitation of the laser diode. The frequency response to intensity modulation was also measured directly at microwave frequencies. Finally, the FM spectrum was observed using a heterodyne technique and compared with an empirical model. The spectrum of intensity fluctuations shows a peak near the relaxation oscillation frequency. This is a good indication of the cutoff frequency for direct current modulation of the laser diode. The behavior of the modulated laser diode is well characterized by the simultaneous intensity and frequency modulation taking into account a phase difference between the two.

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

    EPA Science Inventory

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

  6. Multi-wavelength transmittance photoplethysmography with near infrared laser diodes during exercise

    NASA Astrophysics Data System (ADS)

    Lopez Silva, S. M.; Giannetti, R.; Dotor, M. L.; Golmayo, D.; Martin, P.; Miguel-Tobal, F.; Bilbao, A.; Silveira, J. P.

    2005-08-01

    The transmittance photoplethysmographic signals recorded with multiple NIR laser diodes in athletes along a maximal exercise test by treadmill ergometer and the results after processing are presented in comparison to the established reference techniques.

  7. High power diode laser array development using completely indium free packaging technology with narrow spectrum

    NASA Astrophysics Data System (ADS)

    Hou, Dong; Wang, Jingwei; Gao, Lijun; Liang, Xuejie; Li, Xiaoning; Liu, Xingsheng

    2016-03-01

    The high power diode lasers have been widely used in many fields. In this work, a sophisticated high power and high performance horizontal array of diode laser stacks have been developed and fabricated with high duty cycle using hard solder bonding technology. CTE-matched submount and Gold Tin (AuSn) hard solder are used for bonding the diode laser bar to achieve the performances of anti-thermal fatigue, higher reliability and longer lifetime. This array consists of 30 bars with the expected optical output peak power of 6000W. By means of numerical simulation and analytical results, the diode laser bars are aligned on suitable positions along the water cooled cooler in order to achieve the uniform wavelength with narrow spectrum and accurate central wavelength. The performance of the horizontal array, such as output power, spectrum, thermal resistance, life time, etc., is characterized and analyzed.

  8. Diode-pumped continuous-wave Nd:S-VAP/Nd:YVO4 hybrid laser

    NASA Astrophysics Data System (ADS)

    Shen, Deyuan; Song, Jie; Li, Cheng; Kim, Nam Seong; Ueda, Ken-ichi

    2000-04-01

    A laser-diode end-pumped continuous wave hybrid Nd:S-VAP and Nd:YVO4 laser was demonstrated. The two crystals were combined to construct a hybrid-crystal which has a broader effective absorption bandwidth. The hybrid laser can operate efficiently without the need to control the temperature of pump diode. In a combination with the c axes of Nd:S-VAP and Nd:YVO4 perpendicular to each other, the polarization states of the laser output can be selected by changing the pumping wavelength of laser diode. Thermal compensated hybrid- crystal concept has been proposed and discussed based on the combination of laser crystals with negative and positive thermal coefficient of the refractive indices.

  9. High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure

    SciTech Connect

    Liu, Lei; Qu, Hongwei; Liu, Yun; Zhang, Yejin; Zheng, Wanhua; Wang, Yufei; Qi, Aiyi

    2014-12-08

    900 nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5 μm-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75 W under continuous wave test and over 10 W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.

  10. Analysis and measurement of the external modulation of modelocked laser diodes (Relative noise performance)

    NASA Astrophysics Data System (ADS)

    Lam, B. C.; Kellner, A. L.; Campion, D. C.; Costa, J. M.; Yu, P. K. L.

    1991-02-01

    The measurement of the relative intensity noise (RIN) of a ridge waveguide laser and a distributed feedback laser under CW, external cavity, direct modulation, and modelocking conditions is presented. The purpose is to determine the relative noise performance of modelocked laser diodes. The results indicate that the RIN of modelocked lasers are comparable to CW lasers but lower than both external cavity lasers (optimized for modelocking but without the applied RF) and directly modulated lasers; the difference can be as much as 5 optical dB. The microwave carriers produced optically by the direct modulation and modelocking of laser diodes are also compared. The comparison determines that modelocked lasers produce less noisy and more RF power efficient microwave carriers. However, no difference in microwave linewidth is detected within the limit of the resolution bandwidth of the detection system.

  11. High-resolution monitoring of the hole depth during ultrafast laser ablation drilling by diode laser self-mixing interferometry.

    PubMed

    Mezzapesa, Francesco P; Ancona, Antonio; Sibillano, Teresa; De Lucia, Francesco; Dabbicco, Maurizio; Lugarà, Pietro Mario; Scamarcio, Gaetano

    2011-03-15

    We demonstrate that diode laser self-mixing interferometry can be exploited to instantaneously measure the ablation front displacement and the laser ablation rate during ultrafast microdrilling of metals. The proof of concept was obtained using a 50-μm-thick stainless steel plate as the target, a 120 ps/110 kHz microchip fiber laser as the machining source, and an 823 nm diode laser with an integrated photodiode as the probe. The time dependence of the hole penetration depth was measured with a 0.41 µm resolution.

  12. Determination of Freon-12 in the atmosphere by the diode-laser spectrosocopy method

    SciTech Connect

    Zasavitskii, I.I.; Kosichkin, Y.V.; Nadezhdinskii, A.I.; Stepanov, E.V.; Tishcheako, A.Y.

    1986-04-10

    The aim of the auhtors' work is the development of a method whereby the Freon-12 concentration in the atmosphere is determined by the use of diode-laser spectroscopy. The proposed method of Freon-12 determination is based on a combination of cryogenic concentration and diode-laser spectroscopy, validated by the analysis of air mixtures of known composition. The Freon-12 detection limit is 1. 10/sup -8/ vol.%.

  13. Two-wavelength laser-diode heterodyne interferometry with one phasemeter

    NASA Astrophysics Data System (ADS)

    Onodera, Ribun; Ishii, Yukihiro

    1995-12-01

    A two-wavelength laser-diode interferometer that is based on heterodyne detection with one phasemeter has been constructed. Two laser diodes are frequency modulated by mutually inverted sawtooth currents on an unbalanced interferometer. One can measure the tested phase at a synthetic wavelength from the sum of the interference beat signals by synchronizing them with the modulation frequency. The experimental result presented shows a phase-measurement range with a 4.7- mu m synthetic wavelength.

  14. Spectrally narrowed external-cavity high-power stack of laser diode arrays.

    PubMed

    Zhu, H; Ruset, I C; Hersman, F W

    2005-06-01

    We describe an effective external cavity for narrowing the spectral linewidth of a multiarray stack of laser diode arrays. For a commercially available 279-W free-running five-array laser diode array operating at 60 A, we narrow the spectral linewidth to 0.40 nm at FWHM with 115 W of cw power output. This technique leads to the possibility of higher-efficiency, lower-cost production of hyperpolarized noble gases for magnetic resonance imaging.

  15. High-brightness 800nm fiber-coupled laser diodes

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Levy, Moshe; Rappaport, Noam; Tessler, Renana; Peleg, Ophir; Shamay, Moshe; Yanson, Dan; Klumel, Genadi; Dahan, Nir; Baskin, Ilya; Shkedi, Lior

    2014-03-01

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. Single emitters offer reliable multi-watt output power from a 100 m lateral emission aperture. By their combination and fiber coupling, pump powers up to 100 W can be achieved from a low-NA fiber pigtail. Whilst in the 9xx nm spectral range the single emitter technology is very mature with <10W output per chip, at 800nm the reliable output power from a single emitter is limited to 4 W - 5 W. Consequently, commercially available fiber coupled modules only deliver 5W - 15W at around 800nm, almost an order of magnitude down from the 9xx range pumps. To bridge this gap, we report our advancement in the brightness and reliability of 800nm single emitters. By optimizing the wafer structure, laser cavity and facet passivation process we have demonstrated QCW device operation up to 19W limited by catastrophic optical damage to the 100 μm aperture. In CW operation, the devices reach 14 W output followed by a reversible thermal rollover and a complete device shutdown at high currents, with the performance fully rebounded after cooling. We also report the beam properties of our 800nm single emitters and provide a comparative analysis with the 9xx nm single emitter family. Pump modules integrating several of these emitters with a 105 μm / 0.15 NA delivery fiber reach 35W in CW at 808 nm. We discuss the key opto-mechanical parameters that will enable further brightness scaling of multi-emitter pump modules.

  16. Diode end pumped laser and harmonic generator using same

    NASA Technical Reports Server (NTRS)

    Byer, Robert L. (Inventor); Dixon, George J. (Inventor); Kane, Thomas J. (Inventor)

    1988-01-01

    A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume. In another embodiment, a non-linear, doubling material is disposed in an optical resonator external of the laser gai medium for improved stability of the second harmonic generation process. In another embodiment, the laser gain medium andthe non-linear material are bonded together by means of an optically transparent cement to form a mechanically stable, monolithic structure. In another embodiment, the non-linear material has reflective faces formed thereon to define a ring resonator to decouple reflections from the non-linear medium back to the gain medium for improved stability.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  18. Tunable light source with GaN-based violet laser diode

    NASA Astrophysics Data System (ADS)

    Omori, Masaki; Mori, Naoki; Dejima, Norihiro

    2013-03-01

    GaN based violet Laser Diode has been applying for the industrial market with unique high potential characters. It has possibility Replacing Gas lasers, Dye Lasers, SHG lasers and Solid-state Lasers and more. Diode based laser extreme small and low costs at the high volume range. In addition GaN Laser has high quality with long lifetime and has possibility to cover the wide wavelength range as between 375 to 520nm. However, in general, diode based laser could only lase with Longitudinal Multi Mode. Therefore applicable application field should be limited and it was difficult to apply for the analysis. Recently, Single Longitudinal Mode laser with GaN diode has also be accomplished with external cavity by Nichia Corporation. External cavity laser achieved at least much higher than 20dB SMSR. The feature of installing laser is that Laser on the front facet with AR coating to avoid chip mode lasing. In general, external cavity laser has been required precision of mechanical assembly and Retention Capability. Nichia has gotten rid of the issue with Intelligence Cavity and YAG Laser welding assembly technique. This laser has also been installed unique feature that the longitudinal mode could be maintained to Single Mode lasing with installing internal functional sensors in the tunable laser.*1,*2 This tunable laser source could lock a particular wavelength optionally between 390 to 465nm wavelength range. As the results, researcher will have benefit own study and it will be generated new market with the laser in the near future.

  19. Promoting Robust Design of Diode Lasers for Space: A National Initiative

    NASA Technical Reports Server (NTRS)

    Tratt, David M.; Amzajerdian, Farzin; Kashem, Nasir B.; Shapiro, Andrew A.; Mense, Allan T.

    2007-01-01

    The Diode-laser Array Working Group (DAWG) is a national-level consumer/provider forum for discussion of engineering and manufacturing issues which influence the reliability and survivability of high-power broad-area laser diode devices in space, with an emphasis on laser diode arrays (LDAs) for optical pumping of solid-state laser media. The goals of the group are to formulate and validate standardized test and qualification protocols, operational control recommendations, and consensus manufacturing and certification standards. The group is using reliability and lifetime data collected by laser diode manufacturers and the user community to develop a set of standardized guidelines for specifying and qualifying laser diodes for long-duration operation in space, the ultimate goal being to promote an informed U.S. Government investment and procurement strategy for assuring the availability and durability of space-qualified LDAs. The group is also working to establish effective implementation of statistical design techniques at the supplier design, development, and manufacturing levels to help reduce product performance variability and improve product reliability for diodes employed in space applications

  20. Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

    PubMed

    González-Rodríguez, Alberto; de Dios López-González, Juan; del Castillo, Juan de Dios Luna; Villalba-Moreno, Juan

    2011-05-01

    Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully

  1. Second harmonic generation of diode laser radiation in KNbO3

    NASA Astrophysics Data System (ADS)

    van Hulst, Niko F.; Heesink, Gerard J.; de Leeuw, H.; Bolger, Bouwe

    1991-02-01

    Both CW and pulsed diode lasers covering the wavelength region 855-912 nm have been investigated for the frequency doubling in KNbO. The influence of the spectral distribution mode character and the optical geometry of the laser beam have been investigated for several AlGaAs diode lasers. Second harmonic radiation with maximum efficiency of typically 1 has been detected both by temperature tuning CT 10-130 C noncritical phase matching) and by angle tuning. Results clearly demonstrate the critical aspects of the laser mode spectrum and the beam geometry as to the phase matching criterion in frequency doubling.

  2. High-power AlGaAs channeled substrate planar diode lasers for spaceborne communications

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  3. External cavity diode laser based upon an FBG in an integrated optical fiber platform.

    PubMed

    Lynch, Stephen G; Holmes, Christopher; Berry, Sam A; Gates, James C; Jantzen, Alexander; Ferreiro, Teresa I; Smith, Peter G R

    2016-04-18

    An external cavity diode laser is demonstrated using a Bragg grating written into a novel integrated optical fiber platform as the external cavity. The cavity is fabricated using flame-hydrolysis deposition to bond a photosensitive fiber to a silica-on-silicon wafer, and a grating written using direct UV-writing. The laser operates on a single mode at the acetylene P13 line (1532.83 nm) with 9 mW output power. The noise properties of the laser are characterized demonstrating low linewidth operation (< 14 kHz) and superior relative intensity noise characteristics when compared to a commercial tunable external cavity diode laser. PMID:27137276

  4. Use of the 810 nm diode laser: soft tissue management and orthodontic applications of innovative technology.

    PubMed

    Sarver, David M

    2006-10-01

    Innovative technologies such as the diode laser have provided considerable benefit to dental patients and professionals. Facilitating efficient cutting of tissue and subsequent coagulation, the soft tissue laser enhances tissue healing and can reduce postsurgical complications. Due to the conservative nature of treatment accomplished with the laser this technology is very useful in orthodontic procedures. The diode laser is utilized in both esthetic enhancement of the smile, and treatment management of soft tissue issues that impede efficient orthodontic treatment. Its clinical application will be illustrated in a series of orthodontic cases.

  5. Comparison between MIM and Schottky diodes as harmonic mixers for visible lasers and microwave sources

    NASA Astrophysics Data System (ADS)

    Acef, O.; Hilico, L.; Bahoura, M.; Nez, F.; De Natale, P.

    1994-07-01

    We report our results on high order harmonic mixing between two visible lasers and microwave radiations in point-contact diodes. We have observed up to the 17th harmonic mixing order between two lasers ( Δv = 150 GHz) and a X-band klystron in a Schottky diode. We have been able to monitor very large laser frequency differences, up to 540 GHz (≈ 1.3 nm) with a good signal to noise ratio while using a very low power microwave source (20 mW/90 GHz). These results can be improved by using stabilized lasers and phase-locked microwave sources.

  6. Spatial Combining of Laser-Diode Beams for Pumping an NPRO

    NASA Technical Reports Server (NTRS)

    Gelsinger, Paul; Liu, Duncan; Mulder, Jerry; Aguayo, Francisco

    2008-01-01

    A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, a Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained in this article, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. To minimize coupling loss, one must ensure that the NA (approximately equal to 0.3) of the combined laser-diode beams is less than the NA of the fiber. The A(Omega) of the laser-diode beam in the slow-axis plane is 1/1.3 as large as that of the fiber. This A(Omega) is small enough to enable efficient coupling of light into the optical fiber, but too large for combining of beams in the slow-axis plane. Therefore, a pair of cylindrical lenses is used to cancel the slow-axis plane magnification introduced by the on-cylindrical lenses used to effect magnification in the fast-axis plane.

  7. 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.

  8. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

    NASA Technical Reports Server (NTRS)

    Liu, Duncan; Wilson, Daniel; Qiu, Yueming; Forouhar, Siamak

    2007-01-01

    An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

  9. Diode Laser Sensors for Arc-Jet Characterization

    NASA Technical Reports Server (NTRS)

    Hanson, Ronald K.

    2005-01-01

    The development and application of tunable diode laser (TDL) absorption sensors to monitor the health and operating conditions in the large-scale 60 MW arc-heated- plasma wind-tunnel at NASA Ames Research Center is reported. The interactive heating facility (THF) produces re-entry flow conditions by expanding the gas heated in a constricted plasma arc-heater to flow at high velocity over a model located in a test cabin. This facility provides the conditions needed to test thermal protective systems for spacecraft re-entering the earth s atmosphere. TDL sensors are developed to monitor gas flows in both the high-temperature constricted flow and the supersonic expansion flow into test cabin. These sensors utilize wavelength-tuned diode lasers to measure absorption transitions of atomic oxygen near 777.2 nm, atomic nitrogen near 856.8 nm, and atomic copper near 793.3 nm. The oxygen and nitrogen sensors measure the population density in exited electronic states of these atoms. The measurements combined with the assumption of local thermal and chemical equilibrium yield gas temperature (typically near 7,000K). The nitrogen and oxygen population temperatures are redundant, and their close agreement provides an important test of the local thermal equilibrium assumption. These temperature sensors provide time-resolved monitors of the operating conditions of the arc-heater and can be used to verify and control the test conditions. An additional TDL sensor was developed to monitor the copper concentration in the arc-heater flow yielding values as high as 13 ppm. Measurements of copper in the flow can identify flow conditions with unacceptably rapid electrode erosion, and hence this sensor provides valuable information needed to schedule maintenance to avoid costly arc-heater failure. TDL sensors were also developed for measurements in the test cabin, where absorption measurements of the populations of argon and molecular nitrogen in excited metastable electronic states

  10. GaAs Substrates for High-Power Diode Lasers

    NASA Astrophysics Data System (ADS)

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

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

  11. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

    PubMed Central

    Chang, Feng-Yu; Tsai, Meng-Tsan; Wang, Zu-Yi; Chi, Chun-Kai; Lee, Cheng-Kuang; Yang, Chih-Hsun; Chan, Ming-Che; Lee, Ya-Ju

    2015-01-01

    Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging. PMID:26568136

  12. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

    NASA Astrophysics Data System (ADS)

    Chang, Feng-Yu; Tsai, Meng-Tsan; Wang, Zu-Yi; Chi, Chun-Kai; Lee, Cheng-Kuang; Yang, Chih-Hsun; Chan, Ming-Che; Lee, Ya-Ju

    2015-11-01

    Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

  13. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode.

    PubMed

    Chang, Feng-Yu; Tsai, Meng-Tsan; Wang, Zu-Yi; Chi, Chun-Kai; Lee, Cheng-Kuang; Yang, Chih-Hsun; Chan, Ming-Che; Lee, Ya-Ju

    2015-11-16

    Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

  14. Laser diode pumped, erbium-doped, solid state laser with high slope efficiency

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon; Allen, R.; Kintz, G.

    1989-10-01

    A laser and method for producing a laser emission at a wavelength of substantially 2.8 microns is disclosed. In a preferred embodiment of the invention, the laser comprises laser diode means for emitting a pump beam at a preselected wavelength; and a crystal having a preselected host material doped with a predetermined percent concentration of erbium activator ions sufficient to produce a laser emission at substantially 2.8 microns at a slope efficiency of at least 5 percent, but preferrably 10 percent, when the crystal is pumped by the pump beam. It is well known that the human body is comprised of approximately 70 percent water, with various human tissues containing about 60 to 90 percent of water, and bone and cartilage containing about 30 to 40 percent of water. Since the 2.8 micron wavelength has a substantially maximum absorption in water, this 2.8 micron wavelength is the ideal wavelength to use for a large variety of medical laser applications on the human body. A 2.8 micron wavelength laser could be used for precise surgery in such exemplary applications as brain surgery, neurosurgery, eye surgery, plastic surgery, burn treatment, and the removal of malignancies.

  15. Laser-diode-pumped, erbium-doped, solid-state laser with high slope efficiency

    SciTech Connect

    Esterowitz, L.; Allen, R.; Kintz, G.

    1989-10-31

    A laser and method for producing a laser emission at a wavelength of substantially 2.8 microns is disclosed. In a preferred embodiment of the invention, the laser comprises laser diode means for emitting a pump beam at a preselected wavelength; and a crystal having a preselected host material doped with a predetermined percent concentration of erbium activator ions sufficient to produce a laser emission at substantially 2.8 microns at a slope efficiency of at least 5 percent, but preferrably 10 percent, when the crystal is pumped by the pump beam. It is well known that the human body is comprised of approximately 70% water, with various human tissues containing about 60% to 90% of water, and bone and cartilage containing about 30% to 40% of water. Since the 2.8 micron wavelength has a substantially maximum absorption in water, this 2.8 micron wavelength is the ideal wavelength to use for a large variety of medical laser applications on the human body. A 2.8 micron wavelength laser could be used for precise surgery in such exemplary applications as brain surgery, neurosurgery, eye surgery, plastic surgery, burn treatment and the removal of malignancies.

  16. Rapid and broad wavelength sweeping of standard telecommunication distributed feedback laser diode.

    PubMed

    Njegovec, Matej; Donlagic, Denis

    2013-06-01

    This Letter presents a method for the fast and broad wavelength sweeping of a standard setup of a diode's active region and its immediate vicinity, which contain the diode's optical feedback system. The selective and rapid heating of the active region is possible due to the confinement of the voltage drop to the active diode's region that has submicrometer thickness. Using the presented method and an off-the-shelf telecommunication distributed feedback laser diode, we demonstrate wavelength sweeps in excess of 10 nm that were completed in about 200 ns, while generating average optical power in excess of 50 mW. In spite of high-amplitude current-drive pulses, 6000 h continuous operation of the diode within such an operational regime did not show any significant degradation of the diode's performance.

  17. Compact multiphoton/single photon laser scanning microscope for spectral imaging and fluorescence lifetime imaging.

    PubMed

    Ulrich, Volker; Fischer, Peter; Riemann, Iris; Königt, Karsten

    2004-01-01

    An inverted fluorescence microscope was upgraded into a compact three-dimensional laser scanning microscope (LSM) of 65 x 62 x 48 cm dimensions by means of a fast kHz galvoscanner unit, a piezodriven z-stage, and a picosecond (ps) 50 MHz laser diode at 405 nm. In addition, compact turn-key near infrared femtosecond lasers have been employed to perform multiphoton fluorescence and second harmonic generation (SHG) microscopy. To expand the features of the compact LSM, a time-correlated single photon counting unit as well as a Sagnac interferometer have been added to realize fluorescence lifetime imaging (FLIM) and spectral imaging. Using this unique five-dimensional microscope, TauMap, single-photon excited (SPE), and two-photon excited (TPE) cellular fluorescence as well as intratissue autofluorescence of water plant leaves have been investigated with submicron spatial resolution, <270 ps temporal resolution, and 10 nm spectral resolution. PMID:15536977

  18. Generation of high-power nanosecond pulses from laser diode-pumped Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Chan, Kinpui

    1988-01-01

    Simulation results are used to compare the pulse energy levels and pulse energy widths that can be achieved with LD-pumped Nd:YAG lasers for both the pulse-transmission mode (PTM) and pulse-reflection mode (PRM) Q-switching methods for pulse energy levels up to hundreds of microjoules and pulse widths as short as 1 ns. It is shown that high-power pulses with pulse widths as short as 1 ns can be generated with PTM Q-switched in LD-pumped Nd:YAG lasers. With the PRM Q-switching method, pulse widths as short as 2 ns and pulse energy at the level of a few hundred microjoules can also be achieved but require pumping with 8-10-mJ AlGaAs laser diode arrays.

  19. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.

  20. Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique.

    PubMed

    Salamu, Gabriela; Jipa, Florin; Zamfirescu, Marian; Pavel, Nicolaie

    2014-03-10

    We report on realization of buried waveguides in Nd:YAG ceramic media by direct femtosecond-laser writing technique and investigate the waveguides laser emission characteristics under the pump with fiber-coupled diode lasers. Laser pulses at 1.06 μm with energy of 2.8 mJ for the pump with pulses of 13.1-mJ energy and continuous-wave output power of 0.49 W with overall optical efficiency of 0.13 were obtained from a 100-μm diameter circular cladding waveguide realized in a 0.7-at.% Nd:YAG ceramic. A circular waveguide of 50-μm diameter yielded laser pulses at 1.3 μm with 1.2-mJ energy.

  1. 2-kW cw fiber-coupled diode laser system

    NASA Astrophysics Data System (ADS)

    Dorsch, Friedhelm; Daiminger, Franz X.; Hennig, Petra; Bluemel, Veit

    2000-04-01

    We have developed a high-power laser system that is based on actively cooled GaAs diode laser stacks. Fast axis collimation and subsequent beam rearrangement generates a symmetric laser beam in respect to the beam parameter product along the two main axes. By polarization and wavelength coupling 100 diode laser elements can be coupled into one fiber at a beam parameter product of less than 200 mm*mrad in both directions and more than 2 kW cw output power at the workpiece. At a spot diameter of less than 1 mm the power density exceeds 250 kW/cm2. First material processing experiments show that deep welding at working speeds that meet industrial requirements in steel can be observed. High-power diode lasers show that they become suitable for industrial work.

  2. Diode-pumped Nd:YCOB self-frequency-doubling green laser at 530 nm

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Sang, L. F.

    2011-08-01

    It is reported that efficient continuous-wave (CW) self-frequency-doubling green laser at 530 nm performed with a diode-pumped Nd3+:YCa4O(BO3)3 (Nd:YCOB) laser. With a diode pump power of 14.3 W, TEM00 mode green laser at 530 nm of 1.07 W is obtained. At the output power level of 1.07 mW, the output stability is better than 5%. The beam quality M2 value is about 1.37. To the best of our knowledge, this is the highest power laser at 530 nm generated by self-frequency doubling of a diode pumped Nd:YCOB laser.

  3. Diode-pumped Nd:YCOB self-frequency-doubling red laser at 666 nm

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Xiao, S. C.; Sun, X. P.

    2011-08-01

    It is reported that efficient continuous-wave (CW) self-frequency-doubling red laser at 666 nm performed with a diode-pumped Nd3+:YCa4O(BO3)3 (Nd:YCOB) laser. With a diode pump power of 14.3 W, TEM00 mode red laser at 666 nm of 570 mW is obtained. At the output power level of 570 mW, the output stability is better than 3.5%. The beam quality M2 value is about 1.25. To the best of our knowledge, this is the highest power laser at 666 nm generated by self-frequency doubling of a diode pumped Nd:YCOB laser.

  4. Diode laser soft-tissue surgery: advancements aimed at consistent cutting, improved clinical outcomes.

    PubMed

    Romanos, Georgios E

    2013-01-01

    Laser dentistry and soft-tissue surgery, in particular, have become widely adopted in recent years. Significant cost reductions for dental lasers and the increasing popularity of CADCAM, among other factors, have contributed to a substantial increase in the installed base of dental lasers, especially soft-tissue lasers. New development in soft-tissue surgery, based on the modern understanding of laser-tissue interactions and contact soft-tissue surgery mechanisms, will bring a higher quality and consistency level to laser soft-tissue surgery. Recently introduced diode-laser technology enables enhanced control of side effects that result from tissue overheating and may improve soft-tissue surgical outcomes.

  5. Diode-pumped Q-switched Nd{sup 3+} : YAG laser operating in a wide temperature range without thermal stabilisation of pump diodes

    SciTech Connect

    Vainshenker, A E; Vilenskiy, A V; Kazakov, A A; Lysoy, B G; Mikhailov, L K; Pashkov, V A

    2013-02-28

    A model sample of a compact low-power-consumption Nd{sup 3+} : YAG laser emitting 20-mJ pulses with a pulse repetition rate up to 20 Hz (in cyclic duty) at a wavelength of 1064 nm is developed and studied. The laser is designed for operating at external temperatures from -40 to +50 deg C. This was achieved by using quasi-end diode pumping without thermal stabilisation of pump diodes. (laser optics 2012)

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

    PubMed

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

    2016-09-01

    The prevalence of peri-implantitis and the absence of a standard approach for decontamination of the dental implant surface have led to searches for effective therapies. Since the source of diode lasers is portable, has reduced cost, and does not cause damage to the titanium surface of the implant, high-power diode lasers have been used for this purpose. The effect of laser irradiation on the implants is the elevation of the temperature surface. If this elevation exceeds 47 °C, the bone tissue is irreversibly damaged, so for a safety therapy, the laser parameters should be controlled. In this study, a diode laser of GaAsAl was used to irradiate titanium dental implants, for powers 1.32 to 2.64 W (real) or 2.00 to 4.00 W (nominal), in continuous/pulsed mode DC/AC, with exposure time of 5/10 s, with/without air flow for cooling. The elevation of the temperature was monitored in real time in two positions: cervical and apical. The best results for decontamination using a 968-nm diode laser were obtained for a power of 1.65 and 1.98 W (real) for 10 s, in DC or AC mode, with an air flow of 2.5 l/min. In our perspective in this article, we determine a suggested approach for decontamination of the dental implant surface using a 968-nm diode laser. PMID:27365109

  7. Influence of storage causing packaging stress changes on smile effect for diode laser arrays

    NASA Astrophysics Data System (ADS)

    Xu, Hui-wu; Zhang, Yong; Fang, Yu-suo; Liu, Xiao-wen; Niu, Jiang-li; Yuan, Chun-sheng; Li, Cheng-yan; Wang, Yuan-yuan; Wang, Xiao-yan; Shen, Mu; An, Zhen-feng

    2013-09-01

    The smile effect is caused by the thermal stress in the packaging process. If packaging technology of a diode laser array is poor, smile effect will be very bad and the smile effect will vary with storage time. To accurately measure smile effect and to objectively compare the different measuring methods for smile effect, a set of optical system is designed for measuring the smile effect. By using an image amplification method, the smile effect of a diode laser array is accurately measured, and the measurement error is about +/-0.1μm. By researching, the heat sink surface flatness has little influence on smile effect. However the solder quality is a critical factor for smile effect. That is to say, there is more voids, the corresponding smile effect is more serious in this area. Reflow soldering curve has a major impact on smile effect in the packaging process of a diode laser array .During reflow soldering process, accelerated cooling before solidification and slow cooling after solidification not only can commendably reduce voids and smile effect ,but also can effectively solve the smile effect with storage time variation problem .By optimizing the reflow soldering curve of a diode laser array , the smile effect has been controlled within +/-0.5μm..As the smile effect values of a semiconductor laser array is diminished and the beam quality of a laser diode array is improved significantly. The recommended method provides favorable conditions for the beam collimation and shaping of a semiconductor laser array.

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

    PubMed

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

    2016-09-01

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

  9. 2000W high beam quality diode laser for direct materials processing

    NASA Astrophysics Data System (ADS)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

    2011-11-01

    This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

  10. Continuously tunable single-frequency 1.52-{mu}m diode laser for gas analysis

    SciTech Connect

    Gladyshev, A V; Belovolov, M I; Vasil'ev, Sergei A; Medvedkov, O I; Duraev, V P; Nedelin, E T; Nadezhdinskii, Aleksandr I; Ponurovskii, Ya Ya

    2005-03-31

    A single-frequency continuously tunable diode laser with a hybrid fibre Bragg grating resonator (hybrid laser) is built for recording the absorption line of ammonia. The continuous tuning within 40 GHz (1.33 cm{sup -1}) was achieved for the first time for a hybrid laser emitting 5 mW in the line of width {delta}{nu} {<=} 15 MHz (0.0005 cm{sup -1}) with the side-mode suppression exceeding 20 dB. (lasers)

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

    PubMed Central

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

    2013-01-01

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

  12. Management of Chronic Periodontitis Using Chlorhexidine Chip and Diode Laser-A Clinical Study

    PubMed Central

    Ambooken, Majo; Mathew, Jayan Jacob; Issac, Annie Valayil; Kunju, Ajithkumar Parachalil; Parameshwaran, Renjith Athirkandathil

    2016-01-01

    Introduction The use of adjuncts like chlorhexidine local delivery and diode laser decontamination have been found to improve the clinical outcomes of scaling and root planing in non-surgical periodontal therapy in patients with chronic periodontitis. Aim To evaluate the effects of diode laser and chlorhexidine chip as adjuncts to scaling and root planing in the management of chronic periodontitis. The objective is to evaluate the outcome of chlorhexidine chip and diode laser as adjuncts to scaling and root planing on clinical parameters like Plaque Index, Gingival Index, probing pocket depth and clinical attachment level. Study and Design Department of Periodontics. Randomized clinical trial with split mouth design. Materials and Methods Fifteen chronic periodontitis patients having a probing pocket depth of 5mm-7mm on at least one interproximal site in each quadrant of the mouth were included in the study. After initial treatment, four sites in each patient were randomly subjected to scaling and root planing (control), chlorhexidine chip application (CHX chip group), diode laser (810 nm) decontamination (Diode laser group) or combination of both (Diode laser and chip group). Plaque Index (PI), Gingival Index (GI), probing pocket depth (PPD) and clinical attachment level (CAL) were assessed at baseline, one month and three months. Statistical analysis Results were statistically analysed using paired T test, one-way ANOVA, Tukey’s HSD test and repeated measure ANOVA. Results Post-treatment, the test and control sites showed a statistically significant reduction in PI, GI, PPD, and CAL. After three months, a mean PPD reduction of 1.47±0.52 mm in control group, 1.40±0.83 mm in diode laser group, 2.67±0.62 mm in CHX group, and 2.80± 0.77 mm in combination group was seen. The mean gain in CAL were 1.47±0.52 mm in the control group, 1.40±0.83 mm in diode laser group, 2.67± 0.49 mm in CHX group and 2.67± 0.82 mm in combination group respectively. The

  13. Laparoscopic Partial Nephrectomy with Diode Laser: A Promising Technique

    PubMed Central

    Knezevic, Nikola; Maric, Marjan; Grkovic, Marija Topalovic; Krhen, Ivan; Kastelan, Zeljko

    2014-01-01

    Abstract Objective: The aim of this study was to evaluate application of diode laser in laparoscopic partial nephrectomy (LPN), and to question this technique in terms of ease of tumor excision and reduction of warm ischemia time (WIT). Background data: LPN is the standard operative method for small renal masses. The benefits of LPN are numerous, including preserving renal function and prolonging overall survival. However, reduction of WIT remains main challenge in this operation. In order to shorten WIT, many techniques have been developed, with variable results. Patients and methods: We performed a prospective collection and analysis of health records for patients who were operated on between March 2011 and August 2012. Inclusion criteria were single tumor ≤4 cm, predominant exophytic growth and intraparenchymal depth ≤1.5 cm, with a minimum distance of 5 mm from the urinary collecting system. Results: We operated on 17 patients. Median operative time was 170 min. In all but two patients, we had to perform hilar clamping. Median duration of WIT was 16 min. Pathohistological evaluation revealed clear cell renal cancer and confirmed margins negative for tumor in all cases. Median size of the tumor was 3 cm. Median postoperative hospitalization was 5 days. Average follow up was 11.5 months. There were no intraoperative complications. One postoperative complication was noted: perirenal hematoma. Conclusions: Laser LPN is feasible, and offers the benefit of shorter WIT, with effective tissue coagulation and hemostasis. With operative experience and technical advances, WIT will be reduced or even eliminated, and a solution to some technical difficulties, such as significant smoke production, will be found. PMID:24460067

  14. Diode-Pumped Alkali Atom Lasers 03-LW-024 Final Report

    SciTech Connect

    Page, R H; Beach, R J

    2005-02-16

    The recent work at LLNL on alkali-atom lasers has been remarkably successful and productive. Three main phases (so far) can be identified. First, the concept and demonstration of red lasers using (Ti:sapphire pumping) took place; during this time, Rubidium and Cesium resonance-line lasers were tested, and theoretical models were developed and shown to describe experimental results very reliably. Work done during this first phase has been well documented, and the models from that period are still in use for their predictions and for designing power-scaled lasers. [1 - 3] Second, attempts were made to produce a blue alkali-vapor laser using sequentially-resonant two-step pumping (again, using Ti:sapphire lasers.) Although a blue laser did not result, the physical limitations of our approach are now better-defined. Third, diode-pumped operation of a red laser (Rubidium) was attempted, and we eventually succeeded in demonstrating the world's first diode-pumped gas laser. [4] Because we have a defensible concept for producing an efficient, compact, lightweight, power-scaled laser (tens of kW,) we are in a position to secure outside funding, and would like to find a sponsor. For descriptions of work done during the ''first phase,'' see References [1 - 3] ''Phase two'' work is briefly described in the section ''Blue laser,'' and ''phase three'' work is presented in the section entitled ''Diode-pumped red laser.''

  15. The use of laser diodes for control of uranium vaporization rates

    SciTech Connect

    Hagans, K.; Galkowski, J.

    1993-09-01

    Within the Atomic Vapor Laser Isotope Separation (AVLIS) program we have successfully used the laser absorption spectroscopy technique (LAS) to diagnose process physics performance and control vaporization rate. In the LAS technique, a narrow line-width laser is tuned to an absorption line of the species to be measured. The laser light that is propagated through the sample is and, from this data, the density of the species can be calculated. These laser systems have exclusively consisted of expensive, cumbersome, and difficult to maintain argon-ion-pumped ring dye lasers. While the wavelength flexibility of dye lasers is very useful in a laboratory environment, these laser systems are not well suited for the industrial process control system under development for an AVLIS plant. Diode-lasers offer lower system costs, reduced man power requirements, reduced space requirements, higher system availability, and improved operator safety. We report the. successful deployment and test of a prototype laser diode based uranium vapor rate control system. Diode-laser generated LAS data was used to control the uranium vaporization rate in a hands-off mode for greater than 50 hours. With one minor adjustment the system successfully controlled the vaporization rate for greater than 147 hours. We report excellent agreement with ring dye laser diagnostics and uranium weigh-back measurements.

  16. Diode laser absorption tomography using data compression techniques

    NASA Astrophysics Data System (ADS)

    Lindstrom, Chad; Tam, Chung-Jen; Givens, Ryan; Davis, Doug; Williams, Skip

    2008-02-01

    Tunable diode laser absorption spectroscopy (TDLAS) shows promise for in situ monitoring in high-speed flows. However, the dynamic nature of typical flows of supersonic combustors, gas turbine engines and augmenters can also lead to inhomogenities that cannot be captured by a single line-of-sight TDLAS measurement. Instead, multiple measurements varied over several spatial locations need to be made. In the current study, shock train structure in the isolator section of the Research Cell 18 supersonic combustion facility at Wright-Patterson AFB is measured. Although only two view angles are available for measurement, multiple absorption features along with a priori computational fluid dynamics (CFD) simulations enable estimates of two dimensional flow features to be formed. Vector quantization/kmeans data clustering is used to identify key flow features from the temporal history of the raw sinograms. Through the use of multiple absorption features that are measured nearly simultaneously, an approximate two-dimensional image can be formed. This image can be further refined through the use of an optimal set of basis functions that can be derived from a set of CFD simulations that describes the flow shapes.

  17. Microgravity Diode Laser Spectroscopy Measurements in a Reacting Vortex Ring

    NASA Technical Reports Server (NTRS)

    Chen, Shin-Juh; Dahm, Werner J. A.; Silver, Joel A.; Piltch, Nancy D.

    2001-01-01

    The technique of Diode Laser Spectroscopy (DLS) with wavelength modulation is utilized to measure the concentration of methane in reacting vortex rings under microgravity conditions. From the measured concentration of methane, other major species such as water, carbon dioxide, nitrogen, and oxygen can be easily computed under the assumption of equilibrium chemistry with the method of Interactive Temperature with Assumed Chemistry (ITAC). The conserved scalar approach in modelling the coupling between fluid dynamics and combustion is utilized to represent the unknown variables in terms of the mixture fraction and scalar dissipation rate in conjunction with ITAC. Post-processing of the DLS measurements and the method of ITAC used in computing the species concentration are discussed. From the flame luminosity results, the increase in ring circulation appears to increase the fuel consumption rate inside the reacting vortex ring and the flame height for cases with similar fuel volumes. Preliminary results and application of ITAC show some potential capabilities of ITAC in DLS. The measured concentration of methane, and computed concentrations of water and carbon dioxide agree well with available results from numerical simulations.

  18. Transcutaneous optical telemetry system with infrared laser diode.

    PubMed

    Inoue, K; Shiba, K; Shu, E; Koshiji, K; Tsukahara, K; Oh-umi, T; Masuzawa, T; Tatsumi, E; Taenaka, Y; Takano, H

    1998-01-01

    A transcutaneous telemetry system is indispensable when monitoring and controlling the operation of an artificial heart totally implanted inside the body. A telemetry system using light is more useful than radio waves from the viewpoint of electromagnetic interference and power consumption. In this report, a transcutaneous optical coupler consisting of an infrared laser diode (LD) and a PIN photodiode (PINPD) was evaluated, and the transcutaneous optical coupling and information transmission characteristics were evaluated in in vitro experiments. The wavelength and directional angle of the LD used were 830 nm and 9.5 degrees, respectively. With regard to the directional angle of PINPD, the authors found that a PINPD with a larger directional angle allowed for more deviation between the axes optical axes of the LD and the PINPD. It was also found that the transcutaneous coupler had an optimum distance for the permissible deviation to be maximized. The information signals modulated by the phase shift keying (PSK) were transmitted at a rate of 9,600 bps through goat skin 4 mm thick, and demodulated by the phase locked loop (PLL) on the receiving side. As a result, the information signals were demodulated without any errors in deviation within 10.5 mm at a distance of 11 mm. In conclusion, the transcutaneous optical telemetry system using an infrared LD has sufficient characteristics to monitor and control the operation of an artificial heart totally implanted inside the body. PMID:9831095

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  20. High-Power Broad-Area Diode Lasers and Laser Bars

    NASA Astrophysics Data System (ADS)

    Erbert, Goetz; Baerwolff, Arthur; Sebastian, Juergen; Tomm, Jens

    This review presents the basic ideas and some examples of the chip technology of high-power diode lasers ( λ= 650,-1060,) in connection with the achievements of mounted single-stripe emitters in recent years.In the first section the optimization of the epitaxial layer structure for a low facet load and high conversion efficiency is discussed. The so-called broadened waveguide Large Optical Cavity (LOC) concept is described and also some advantages and disadvantages of Al-free material. The next section deals with the processing steps of epitaxial wafers to make single emitters and bars. Several possibilities to realize contact windows (implantation, insulators, and wet chemical oxidation) and laser mirrors are presented. The impact of heating in the CW regime and some aspects of reliability are the following topics. The calculation of thermal distributions in diode lasers, which shows the need for sophisticated mounting, will be given. In the last part the current state-of-the-art of single-stripe emitters will be reviewed.