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Sample records for 808-nm diode laser

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

    SciTech Connect

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

    2013-10-31

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

  2. Pilot study: intravenous use of indocyanine green as an enhancer for 808-nm diode laser application in the equine

    NASA Astrophysics Data System (ADS)

    Tate, Lloyd P.; Blikslager, Anthony T.; Papich, Mark G.

    2000-05-01

    The 808-nm diode laser, delivering 20 - 40 watts of power, has been produced for medical applications by several manufacturers over the past 10 years. This laser's power output is less than most Neodymium:yttrium aluminum garnet (Nd:YAG) lasers and other high power cutting lasers that use fiberoptic delivery systems. The 808-nm diode laser has not gained popularity in equine transendoscopic laser surgery. Indocyanine green (ICG) is absorbed at 810-nm of light which when concentrated in tissue should be an excellent absorber for the energy produced by the 808-nm diode laser. This study compares the depths and widths of penetration achieved with the 808-nm diode laser after intravenous injection of ICG in equine respiratory tissue. Indocyanine green was administered at two doses: 1.5 mg/kg and 3 mg/kg. The 808-nm diode laser was set to deliver 200 joules of energy. The depths and widths of penetration were also compared to the Nd:YAG laser applied at the same energy setting.

  3. Suppression of electron leakage in 808 nm laser diodes with asymmetric waveguide layer

    NASA Astrophysics Data System (ADS)

    Xiang, Li; Degang, Zhao; Desheng, Jiang; Ping, Chen; Zongshun, Liu; Jianjun, Zhu; Ming, Shi; Danmei, Zhao; Wei, Liu

    2016-01-01

    Electron leakage in GaAs-based separately confined heterostructure 808 nm laser diodes (SCH LDs) has a serious influence on device performance. Here, in order to reduce the energy of electrons injected into the quantum well (QW), an AlGaAs interlayer with a smaller Al component is added between the active region and the n-side waveguide. Numerical device simulation reveals that when the Al-composition of the AlGaAs interlayer and its thickness are properly elected, the electron leakage is remarkably depressed and the characteristics of LDs are improved, owing to the reduction of injected electron energy and the improvement of QW capture efficiency. Project supported by the National Natural Science Foundation of China (Nos. 61377020, 61376089, 61223005, 61176126) and the National Science Fund for Distinguished Young Scholars (No. 60925017).

  4. High-power high-brightness 808nm QCW laser diode mini bars

    NASA Astrophysics Data System (ADS)

    Huang, Hua; Wang, Jun; DeVito, Mark; Bao, Ling; Hodges, Aaron; Zhang, Shiguo; Wise, Damian; Grimshaw, Mike; Xu, Dapeng; Bai, Chendong

    2010-02-01

    A new class of high power high brightness 808 nm QCW laser diode mini bars has been developed. With nLight's nXLT facet passivation technology and improvements in epitaxial structure, mini bars of 3 mm bar width with high efficiency design have tested to over 280 W peak power with peak efficiency over 64% on conduction cooled CS packages, equivalent to output power density near 130 mW/μm. These mini laser bars open up new applications as compact, portable, and low current pump sources. Liftests have been carried out on conduction cooled CS packages and on QCW stacks. Over 370 million (M) shots lifetest with high efficiency design has been demonstrated on CS so far without failure, and over 80 M shots on QCW stacks with accelerated stress lifetest have also proven high reliability on mini bars with high temperature design. Failure analysis determined that the failure mechanism was related to bulk defects, showing that mini laser bars are not prone to facet failure, which is consistent with the large current pulse test and failure analysis on high power single emitters.

  5. Efficient single-mode (TEM{sub 00}) Nd : YVO{sub 4} laser with longitudinal 808-nm diode pumping

    SciTech Connect

    Donin, V I; Yakovin, D V; Yakovin, M D

    2013-10-31

    A single-mode Nd : YVO{sub 4} laser with unidirectional longitudinal pumping by laser diodes with λ = 808 nm and a power of 40 W is studied. In the TEM{sub 00} mode, the output laser power is 24 W with the optical efficiency η{sub opt} = 57.1 % (slope efficiency 63.3 %), which, as far as we know, is the best result for Nd{sup 3+} : YVO{sub 4} lasers with longitudinal pumping at λ = 808 nm from one face of the active crystal. Estimates of thermal effects show that, using a Nd : YVO{sub 4} crystal (length 20 mm, diameter 3 mm, dopant concentration 0.27 at%) with two undoped ends and bidirectional diode pumping with a total power of 170 W, one can obtain an output power of ∼100 W in the TEM{sub 00} mode from one active element. (lasers)

  6. Clinical update: transendoscopic laser surgery for treatment of epiglottic entrapment: Nd:YAG and 808-nm diode laser applied individually and in combination

    NASA Astrophysics Data System (ADS)

    Tate, Lloyd P.; Tudor, R. A.

    1999-06-01

    Hospital records reviewed from 1986-1998 determined that 18 horses were presented for correction of epiglottic entrapment by the aryepiglottic fold. All horses had a history of an abnormal respiratory noise and/or exercise intolerance. In conjunction with epiglottic entrapment, 10 horses had dorsal displacement of the soft palate. Initial confirmation of the epiglottic entrapment was made by endoscopic examination. In addition, 3 horses had radiographs taken of the larynx and pharyngeal region to determine the length of the epiglottis.Laser surgical treatment was performed on the horses in a standing position under sedation. The treatment consisted of axially dividing the aryepiglottic fold from the base of the epiglottis to the tip or beyond by means of a laser fiber introduced through the biopsy channel of an endoscope. The Nd:YAG laser was applied transendoscopically to 11 horses using free fiber technique. Three horses received transendoscopic laser correction using the 808-nm diode laser with the fiber in contact configuration. A combination of both 808-nm diode laser and Nd:YAG lasers were used to facilitate correction in the last 4 horses. Partial re-entrapment occurred in 2 out of the 3 cases in which the 808-nm diode laser was used as a single modality for correction. This did not occur in the horses that received either the Nd:YAG laser treatment or Nd:YAG laser treatment in combination with the 808-nm diode laser. Horses that received either 808-nm diode laser irradiation alone or 808-nm diode laser irradiation in combination with Nd:YAG laser appeared to have less swelling than those that received only Nd:YAG irradiation.

  7. Preliminary report: comparison of 980-nm, 808-nm diode laser enhanced with indocyanine green to the Nd:YAG laser applied to equine respiratory tissue

    NASA Astrophysics Data System (ADS)

    Tate, Lloyd P.; Blikslager, Anthony T.; Campbell, Nigel B.

    2001-05-01

    The Neodynium: Yttrium Aluminum Garnet (Nd:YAG) laser has been the mainstay of performing upper respiratory laser surgery in the equine since 1984. The 808-nm diode laser has also been applied transendoscopically as well as the 980-nm diode laser over recent years. It has been shown that Indocyanine Green (ICG) enhances the performance of the 808- nm laser because it is absorbed at 810 nm of light. The 808- nm laser's tissue interaction combined with ICG is equivalent to or greater than the Nd:YAG laser's cutting ability. The 980-nm diode laser performance was similar to that of the Nd:YAG as determined by the parameters of this study. This study compared the depths and widths of penetration achieved with the 808-nm diode laser after intravenous injection of ICG on equine respiratory tissue. It also compared depths and widths of penetration achieved by the non-contact application of the 980-nm diode laser delivering the same energy of 200 joules. The depths and widths of penetration of both diode lasers were compared to themselves and to the Nd:YAG laser with all factors remaining constant.

  8. Effect of agitation of EDTA with 808-nm diode laser on dentin microhardness.

    PubMed

    Arslan, Hakan; Yeter, Kübra Y; Karatas, Ertugrul; Yilmaz, Cenk B; Ayranci, Leyla B; Ozsu, Damla

    2015-02-01

    The aim of this study is to analyze the effect of agitation of ethylenediaminetetraacetic acid (EDTA) with diode laser at different agitation times on root dentin microhardness. Eighty-four specimens were divided randomly into seven groups, as follows: (1) distilled water, (2) 17% EDTA, (3) EDTA with 60 s ultrasonic agitation, (4) EDTA with 10 s laser agitation, (5) EDTA with 20 s laser agitation, (6) EDTA with 30 s laser agitation, and (7) EDTA with 40 s laser agitation. All of the specimens were irrigated with 5% NaOCl and distilled water except the distilled water group. Microhardness values were calculated before and after the procedures. Statistical analyses were performed using one-way ANOVA and Tukey post hoc tests. Statistically significant differences were determined between the distilled water and other groups. Also, statistically significant differences were observed between EDTA with 40 s laser agitation and EDTA, and EDTA with 10 and 20 s laser agitations. Ultrasonic agitation of EDTA affected microhardness of root dentin similar to EDTA (p > .05). All applications decreased the microhardness of root dentin when compared with distilled water. Agitation of EDTA with diode laser for 40 s caused more reduction in microhardness of root dentin when compared with EDTA. PMID:23793370

  9. Advances in 808nm high power diode laser bars and single emitters

    NASA Astrophysics Data System (ADS)

    Morales, J.; Lehkonen, S.; Liu, G.; Schleuning, D.; Acklin, B.

    2016-03-01

    Key applications for 780-830nm high power diode lasers include the pumping of various gas, solid state, and fiber laser media; medical and aesthetic applications including hair removal; direct diode materials processing; and computer-to-plate (CtP) printing. Many of these applications require high brightness fiber coupled beam delivery, in turn requiring high brightness optical output at the bar and chip level. Many require multiple bars per system, with aggregate powers on the order of kWs, placing a premium on high power and high power conversion efficiency. This paper presents Coherent's recent advances in the production of high power, high brightness, high efficiency bars and chips at 780-830nm. Results are presented for bars and single emitters of various geometries. Performance data is presented demonstrating peak power conversion efficiencies of 63% in CW mode. Reliability data is presented demonstrating <50k hours lifetime for products including 60W 18% fill factor and 80W 28% fill factor conduction cooled bars, and <1e9 shots lifetime for 500W QCW bars.

  10. Thermal effects of λ = 808 nm GaAlAs diode laser irradiation on different titanium surfaces.

    PubMed

    Giannelli, Marco; Lasagni, Massimo; Bani, Daniele

    2015-12-01

    Diode lasers are widely used in dental laser treatment, but little is known about their thermal effects on different titanium implant surfaces. This is a key issue because already a 10 °C increase over the normal body temperature can induce bone injury and compromise osseo-integration. The present study aimed at evaluating the temperature changes and surface alterations experienced by different titanium surfaces upon irradiation with a λ = 808 nm diode laser with different settings and modalities. Titanium discs with surfaces mimicking different dental implant surfaces including TiUnite and anodized, machined surfaces were laser-irradiated in contact and non-contact mode, and with and without airflow cooling. Settings were 0.5-2.0 W for the continuous wave mode and 10-45 μJ, 20 kHz, 5-20 μs for the pulsed wave mode. The results show that the surface characteristics have a marked influence on temperature changes in response to irradiation. The TiUnite surface, corresponding to the osseous interface of dental implants, was the most susceptible to thermal rise, while the machined surfaces, corresponding to the implant collar, were less affected. In non-contact mode and upon continuous wave emission, the temperature rose above the 50 °C tissue damage threshold. Scanning electron microscopy investigation of surface alterations revealed that laser treatment in contact mode resulted in surface scratches even when no irradiation was performed. These findings indicate that the effects of diode laser irradiation on implant surfaces depend on physical features of the titanium coating and that in order to avoid thermal or physical damage to implant surface the irradiation treatment has to be carefully selected. PMID:26423572

  11. Comparison of the photothermal effects of 808nm gold nanorod and indocyanine green solutions using an 805nm diode laser

    NASA Astrophysics Data System (ADS)

    Hasanjee, Aamr M.; Zhou, Feifan; West, Connor; Silk, Kegan; Doughty, Austin; Bahavar, Cody F.; Chen, Wei R.

    2016-03-01

    Non-invasive laser immunotherapy (NLIT) is a treatment method for metastatic cancer which combines noninvasive laser irradiation with immunologically modified nanostructures to ablate a primary tumor and induce a systemic anti-tumor response. To further expand the development of NLIT, two different photosensitizing agents were compared: gold nanorods (GNR) with an optical absorption peak of 808 nm and indocyanine green (ICG) with an optical absorption peak of ~800 nm. Various concentrations of GNR and ICG solutions were irradiated at different power densities using an 805 nm diode laser, and the temperature of the solutions was monitored during irradiation using a thermal camera. For comparison, dye balls made up of a 1:1 volume ratio of gel solution to GNR or ICG solution were placed in phantom gels and were then irradiated using the 805 nm diode laser to imitate the effect of laser irradiation on in vivo tumors. Non-invasive laser irradiation of GNR solution for 2 minutes resulted in a maximum increase in temperature by 31.8 °C. Additionally, similar irradiation of GNR solution dye ball within phantom gel for 10 minutes resulted in a maximum temperature increase of 8.2 °C. Comparatively, non-invasive laser irradiation of ICG solution for 2 minutes resulted in a maximum increase in temperature by 28.0 °C. Similar irradiation of ICG solution dye ball within phantom gel for 10 minutes yielded a maximum temperature increase of only 3.4 °C. Qualitatively, these studies showed that GNR solutions are more effective photosensitizing agents than ICG solution.

  12. Experimental studies for improvement of thermal effects in a high-power fiber-coupled diode laser module operating at 808 nm

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ashraf F.; Hussein, Khalid; Hassan, Mahmoud F.; Talat, Mahmoud M.

    2012-03-01

    High power diode laser module operating at 808 nm is required for different applications, such as developing an efficient high power Nd3+-doped solid state laser and Tm3+ -doped silica fiber laser, industrial, medical and military applications. Optical and thermal images characterization for a fiber-coupled high power diode laser module is presented experimentally for 6.6 Watt output optical power .An external temperature controller system was designed, which stabilizes the central wavelength at 808 nm at 25°C over a wide range of diode laser driving current from 1A to 6 A. without this cooling system, the wavelength changes by 0.35nm/°C for temperature changes from 20°C to 40°C at the same range of the driving current. In this paper we have present a methodology for temperature reduction of a 808 nm high power diode laser module, based on dynamically thermal control, which is known as dynamic thermal management. Stabilization of the output wavelength has been done by using proportional speed control (PSC) of a CPU cooling fan with certain scheme of straight fins heat sink. Two electronic circuits based on pulse width modulation (PWM) in microcontroller and comparators IC have been used. This technique can be considered as an effective mechanism for reducing temperature and power dissipation to make stabilization of the diode laser output wavelength by preventing heat accumulation from the thermo electric cooling (TEC) inside the diode laser module confirmed by thermal images.

  13. High-power 808 nm ridge-waveguide diode lasers with very small divergence, wavelength-stabilized by an external volume Bragg grating.

    PubMed

    Wenzel, H; Häusler, K; Blume, G; Fricke, J; Spreemann, M; Zorn, M; Erbert, G

    2009-06-01

    We present data on ridge-waveguide diode lasers having a vertical far-field divergence of only 11.5 degrees (FWHM) owing to an appropriate waveguide design. The lasers emitted an optical power of more than 1 W into the spatial fundamental mode from a ridge width of 5 microm. The emission wavelength was stabilized to a narrow range around 808 nm by placing a volume Bragg grating in front of the outcoupling facet. PMID:19488129

  14. Microstructure, stress and optical properties of CdTe thin films laser-annealed by using an 808-nm diode laser: Effect of the laser scanning velocity

    NASA Astrophysics Data System (ADS)

    Kim, Nam-Hoon; Park, Chan Il; Lee, Hyun-Yong

    2013-07-01

    A continuous wave 808-nm diode laser was used for the laser annealing process of CdTe thin films at various laser scanning velocities by using a galvanometric mirror. The grains in the laserannealed CdTe thin films grew along the C (111), H (110) and C (311) planes. The lattice constants of the CdTe thin films reached a minimum at a laser annealing velocity of 167 mm/s due to the disintegration of some large grain. The optical band gap energy of the CdTe thin films was inversely proportional to the lattice constant, showing 1.439 eV and 1.474 eV for the CdTe thin films laserannealed with laser scanning velocities of 667 mm/s and 167 mm/s, respectively. The absorbance of the CdTe thin films showed an improved value of 2.80 in the visible spectral region after laser annealing at a laser scanning velocity of 167 mm/s with the appropriate mixture of scattering and transparent grains in CdTe thin films although the crystallinity had deteriorated and showed the small recrystallized grains under this condition.

  15. The protozoan, Paramecium primaurelia, as a non-sentient model to test laser light irradiation: The effects of an 808nm infrared laser diode on cellular respiration.

    PubMed

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2015-07-01

    Photobiomodulation (PBM) has been used in clinical practice for more than 40 years. Unfortunately, conflicting literature has led to the labelling of PBM as a complementary or alternative medicine approach. However, past and ongoing clinical and research studies by reputable investigators have re-established the merits of PBM as a genuine medical therapy, and the technique has, in the last decade, seen an exponential increase in the numbers of clinical instruments available, and their applications. This resurgence has led to a clear need for appropriate experimental models to test the burgeoning laser technology being developed for medical applications. In this context, an ethical model that employs the protozoan, Paramecium primaurelia, is proposed. We studied the possibility of using the measure of oxygen consumption to test PBM by irradiation with an infrared or near-infrared laser. The results show that an 808nm infrared laser diode (1W; 64J/cm²) affects cellular respiration in P. primaurelia, inducing, in the irradiated cells, a significantly (p < 0.05) increased oxygen consumption of about 40%. Our findings indicate that Paramecium can be an excellent tool in biological assays involving infrared and near-infrared PBM, as it combines the advantages of in vivo results with the practicality of in vitro testing. This test represents a fast, inexpensive and straightforward assay, which offers an alternative to both traditional in vivo testing and more expensive mammalian cellular cultures. PMID:26256394

  16. Diode laser (808 nm) applied to oral soft tissue lesions: a retrospective study to assess histopathological diagnosis and evaluate physical damage.

    PubMed

    Angiero, Francesca; Parma, Luisa; Crippa, Rolando; Benedicenti, Stefano

    2012-03-01

    The diode laser is today widely used in oral pathology to excise lesions; however, some controversy surrounds laser surgery, specifically the accuracy of pathological diagnosis and the control over thermal tissue damage. This study aimed to establish if physical damage induced by the diode laser could affect the histopathological diagnosis and to evaluate the damage caused to the resection margins. Between 2005 and 2010, at S. Gerardo Hospital, Milan, 608 cases of soft tissue lesions localized in the oral cavity (cheek, gingiva, buccal mucosa, tongue, and lips) were examined. Specimens were excised with an 808-nm diode laser, output 1.6-2.7 W, in continuous-wave mode with fibers of 320 μm. Specimens were fixed in 10% buffered formalin solution and examined separately under an optical microscope by two pathologists. In all of the specimens, changes to the epithelium, connective tissue and blood vessels, shape of incision damage, and overall width of modified tissues were evaluated. The data for specimens larger than 3 mm excised with the diode laser were not significant in terms of stromal changes or vascular stasis, while epithelial and stromal changes were significantly more frequent in specimens with a mean size below 3 mm; the diagnosis was not achievable in 46.15%. Our data show that the diode laser is a valid therapeutic instrument for excising oral lesions larger than 3 mm in diameter, but induces serious thermal effects in small lesions (mean size below 3 mm). However, from a clinical standpoint, it is suggested necessary that the specimens taken have in vivo a diameter of at least 5 mm in order to have a reliable reading of the histological sample. PMID:21387158

  17. Effective Selection of the TEM00-Mode in a Powerful Nd:YVO4-Laser With the 808 nm Diode Pumping

    NASA Astrophysics Data System (ADS)

    Donin, V. I.; Yakovin, D. V.; Yakovin, М. D.

    2014-03-01

    The problems of an effective selection of the TEM00-mode and thermo-optical distortions in a Nd:YVO4 laser with the longitudinal diode pumping are considered. In an experiment with a 40-watt single-end pumping of the composite YVO4/Nd:YVO4 crystal, the single-mode output power of 24 W at an optical efficiency of ηopt = 57.1% (the slope efficiency of 63.3%) is obtained. Apparently, this is the greatest power for lasers based on the Nd-doped yttrium orthovanadate with the longitudinal pumping at λ = 808 nm from one end of the active crystal. Evaluations of the thermal effects show that when using the Nd:YVO4-crystal (the length 20 mm, the diameter 3 mm, and the doping of 0.27 atomic %) having two undoped ends and the double-end diode pumping with total power of 170 W, one can expect obtaining a 100-watt level of the output power in the TEM00-mode from a single active element.

  18. Scaleable multi-format QCW pump stacks based on 200W laser diode bars and mini bars at 808nm and 940nm

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Karni, Yoram; Klumel, Genady; Openhaim, Yaakov; Cohen, Shalom; Yanson, Dan

    2011-03-01

    Advanced solid state laser architectures place increasingly demanding requirements on high-brightness, low-cost QCW laser diode pump sources, with custom apertures both for side and end rod pumping configurations. To meet this need, a new series of scaleable pump sources at 808nm and 940nm was developed. The stacks, available in multiple output formats, allow for custom aperture filling by varying both the length and quantity of stacked laser bars. For these products, we developed next-generation laser bars based on improved epitaxial wafer designs delivering power densities of 20W/mm of emission aperture. With >200W of peak QCW power available from a full-length 1cm bar, we have demonstrated power scaling to over 2kW in 10-bar stacks with 55% wall plug efficiency. We also present the design and performance of several stack configurations using full-length and reduced-length (mini) bars that demonstrate the versatility of both the bar and packaging designs. We illustrate how the ROBUST HEAD packaging technology developed at SCD is capable of accommodating variable bar length, pitch and quantity for custom rod pumping geometries. The excellent all-around performance of the stacks is supported by reliability data in line with the previously reported 20 Gshot space-grade qualification of SCD's stacks.

  19. Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

    2015-10-01

    The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

  20. Effects of diode 808 nm GaAlAs low-power laser irradiation on inhibition of the proliferation of human hepatoma cells in vitro and their possible mechanism.

    PubMed

    Liu, Yi-Hsiang; Cheng, Chiung-Chi; Ho, Chin-Chin; Pei, Ren-Jeng; Lee, Karen Ying; Yeh, Kun-Tu; Chan, You; Lai, Yih-Shyong

    2004-01-01

    Low-power laser irradiation (LPLI) has come into a wide range of use in medical field. Considering basic research, LPLI can enhance DNA synthesis and increases proliferation rate of human cells. But only a few data about the effects of LPLI on human liver or hepatoma cells are available. The cytoskeleton plays important roles in cell function and therefore is implicated in the pathogenesis of many human liver diseases, including malignant tumors. In our previous study, we found the stability of cytokeratin molecules in human hepatocytes was related to the intact microtubule network that was influenced by colchicine. In this study, we are going to search the effect of LPLI on proliferation of human hepatoma cell line HepG2 and J-5 cells. In addition, the stability of cytokeratin and synemin (one of the intermediate filament-associated proteins) were analyzed under the action of LPLI to evaluate the possible mechanism of LPLI effects on proliferation of human hepatoma cells. In experiment, HepG2 and J-5 cells were cultured in 24-well plate for 24 hours. After irradiation by 130 mW diode 808 nm GaAlAs continue wave laser in different time intervals, the cell numbers were counted. Western blot and immunofluorescent staining examined the expression and distribution of PCNA, cytokeratin and synemin. The cell number counting and PCNA expression were evaluated to determine the proliferation. The organization and expression of cytokeratin and synemin were studied to identify the stability of cytoskeleton affected by LPLI. The results revealed that proliferation of HepG2 and J-5 cells was inhibited by LPLI since the cell number and PCNA expression was reduced. Maximal effect was achieved with 90 and 120 seconds of exposure time (of energy density 5.85 J/cm2 and 7.8 J/cm2, respectively) for HepG2 and J-5, respectively. The decreased ratio of cell number by this dose of irradiation was 72% and 66% in HepG2 and J-5 cells, respectively. Besides that, the architecture of

  1. 808-nm diode-pumped dual-wavelength passively Q-switched Nd:LuLiF4 laser with Bi-doped GaAs

    NASA Astrophysics Data System (ADS)

    Li, S. X.; Li, T.; Li, D. C.; Zhao, S. Z.; Li, G. Q.; Hang, Y.; Zhang, P. X.; Li, X. Y.; Qiao, H.

    2015-09-01

    Diode-pumped CW and passively Q-switched Nd:LuLiF4 lasers with stable, synchronous dual-wavelength operations near 1047 and 1053 nm were demonstrated for the first time. The maximal CW output power of 821 mW was obtained at an incident pump power of 6.52 W. Employing high quality Bi-doped GaAs as saturable absorber, stable dual-wavelength Q-switched operation was realized. Under 6.52 W incident pump power, the minimal pulse duration of 1.5 ns, the largest single pulse energy of 11.32 μJ, and the highest peak power of 7.25 kW were achieved.

  2. MOVPE growth of Al-free 808 nm high power lasers using TBP and TBA in pure N 2 ambient

    NASA Astrophysics Data System (ADS)

    Tang, Xiaohong; Zhang, Baolin; Bo, Baoxue; Mei, Ting; Chin, Mee-Koy

    2006-02-01

    In metalorganic vapor-phase epitaxy (MOVPE) growth of III-V semiconductor compounds and device structures, arsine (AsH 3) and phosphine (PH 3) are normally used as group V precursors and hydrogen is used as the carrier gas, which is very toxic and has safety hazard. In this contribution, MOVPE growths of Al-free 808 nm high power diode lasers by using metalorganic (MO) group V sources, TBAs and TBP, and nitrogen as carrier gas has been reported. InGaAsP/InGaP/GaAs single quantum well (SQW) high power laser structure emitting at 808 nm has been adopted to characterize the material quality. Broad area stripe lasers with the stripe width of 150 μm have been fabricated from the wafers grown by the MOVPE using MO group V sources. Lasing of the device with threshold current density of 506 A/cm 2 has been successfully achieved.

  3. Antibacterial photodynamic therapy with 808-nm laser and indocyanine green on abrasion wound models

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Güney, Melike; Yuksel, Sahru; Gülsoy, Murat

    2015-02-01

    Infections with pathogens could cause serious health problems, such as septicemia and subsequent death. Some of these deaths are caused by nosocomial, chronic, or burn-related wound infections. Photodynamic therapy (PDT) can be useful for the treatment of these infections. Our aim was to investigate the antibacterial effect of indocyanine green (ICG) and 808-nm laser on a rat abrasion wound model infected with the multidrug resistant Staphylococcus aureus strain. Abrasion wounds were infected with a multidrug resistant clinical isolate of S. aureus. ICG concentrations of 500, 1000, and 2000 μg/ml were applied with a 450 J/cm2 energy dose. Temperature change was monitored by a thermocouple system. The remaining bacterial burden was determined by the serial dilution method after each application. Wounds were observed for 11 days posttreatment. The recovery process was assessed macroscopically. Tissue samples were also examined histologically by hematoxylin-eosin staining. Around a 90% reduction in bacterial burden was observed after PDT applications. In positive control groups (ICG-only and laser-only groups), there was no significant reduction. The applied energy dose did not cause any thermal damage to the target tissue or host environment. Results showed that ICG together with a 808-nm laser might be a promising antibacterial method to eliminate infections in animals and accelerate the wound-healing process.

  4. High power 808 nm vertical cavity surface emitting laser with multi-ring-shaped-aperture structure

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Shang, C. Y.; Feng, Y.; Yan, C. L.; Zhao, Y. J.; Wang, Y. X.; Wang, X. H.; Liu, G. J.

    2011-02-01

    The carrier conglomeration effect has been one of the main problems in developing electrically pumped high power vertical cavity surface emitting laser (VCSEL) with large aperture. We demonstrate a high power 808 nm VCSEL with multi-ring-shaped-aperture (MRSA) to weaken the carrier conglomeration effect. Compared with typical VCSEL with single large aperture (SLA), the 300-μm-diameter VCSEL with MRSA has more uniform near field and far field patterns. Moreover, MRSA laser exhibits maximal CW light output power 0.3 W which is about 3 times that of SLA laser. And the maximal wall-plug efficiency of 17.4% is achieved, higher than that of SLA laser by 10%.

  5. Synthesis of WS2 Nanowires as Efficient 808 nm-Laser-Driven Photothermal Nanoagents.

    PubMed

    Macharia, Daniel K; Yu, Nuo; Zhong, Runzhi; Xiao, Zhiyin; Yang, Jianmao; Chen, Zhigang

    2016-06-01

    A prerequisite for the development of photothermal ablation therapy for cancer is to obtain efficient photothermal nanoagents that can be irradiated by near-infrared (NIR) laser. Herein, we have reported the synthesis of WS2 nanowires as photothermal nanoagents by the reaction of WCl6 with CS2 in oleylamine at 280 degrees C. WS2 nanowires have the thickness of -2 nm and length of -100 nm. Importantly, the chloroform dispersion of WS2 nanowires exhibits strong photoabsorption in NIR region. The temperature of the dispersion (0.10-0.50 mg/mL) can increase by 12.8-23.9 degrees C in 5 min under the irradiation of 808 nm laser with a power density of 0.80 W/cm2. Therefore, WS2 nanowires have a great superiority as a new nanoagent for NIR-induced photothermal ablation of cancer, due to their small size and excellent photothermal performance. PMID:27427645

  6. 808-nm laser therapy with a flat-top handpiece photobiomodulates mitochondria activities of Paramecium primaurelia (Protozoa).

    PubMed

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2016-05-01

    Photobiomodulation is proposed as a non-linear process, and only low-level laser therapy (LLLT) is assumed to stimulate exposed cells, whereas high powered laser and fluences can cause negative effects, exhausting the cell's energy reserve as a consequence of excessive photon-based stimulation. In our work, we investigated and compared the effects of 808-nm diode laser (CW) with a new flat-top handpiece. To this purpose, we tested the photobiomodulation effects of 1 and 3 J/cm(2) fluence, both generated by 100 mW or 1 W of laser power and of 64 J/cm(2) of fluence generated by 100 mW, 1 W, 1.5 W or 2 W, as expressed through oxygen consumption and ATP synthesis of Paramecium. Data collected indicates the incremental consumption of oxygen through irradiation with 3 J/cm(2)-100 mW or 64 J/cm(2)-1 W correlates with an increase in Paramecium ATP synthesis. The Paramecium respiration was inhibited by fluences 64 J/cm(2)-100 mW or 64 J/cm(2)-2 W and was followed by a decrease in the endogenous ATP concentration. The 1 J/cm(2)-100 mW or 1 W and 3 J/cm(2)-1 W did not affect mitochondrial activity. The results show that the fluence of 64 J/cm(2)-1 W more than the 3 J/cm(2)-100 mW causes greater efficiency in Paramecium mitochondria respiratory chain activity. Our results suggest that thanks to flat-top handpiece we used, high fluences by high-powered laser have to be reconsidered as an effective and non-invasive therapy. Possible associated benefits of deeper tissue penetration would increase treatment effectiveness and reduced irradiation time. PMID:26984347

  7. Comparison of 885 nm pumping and 808 nm pumping in Nd:CNGG laser operating at 1061 nm and 935 nm

    NASA Astrophysics Data System (ADS)

    Shi, Yuxian; Li, Qinan; Zhang, Dongxiang; Feng, Baohua; Zhang, Zhiguo; Zhang, Huaijin; Wang, Jiyang

    2010-07-01

    A Nd:CNGG laser operated at 935 nm and 1061 nm pumped at 885 nm and 808 nm, respectively, is demonstrated. The 885 nm direct pumping scheme shows some advantages over the 808 nm traditional pumping scheme. It includes higher slope efficiency, lower threshold, and better beam quality at high output power. With the direct pumping, the slope efficiency increases by 43% and the threshold decreases by 10% compared with traditional pumping in the Nd:CNGG laser operated at 935 nm. When the Nd:CNGG laser operates at 1061 nm, the direct pumping increases the slope efficiency by 14% with a 20% reduction in the oscillation threshold.

  8. Increased power of broad-area lasers (808nm/980nm) and applicability to 10-mm bars with up to 1000Watt QCW

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    The new packaging technology from JENOPTIK Laserdiode GmbH and the new chip technology from JENOPTIK Diode Lab GmbH increases the output power, the quality and durability of new broad area lasers. Tests with different pulse widths and duty cycles have been conducted. A maximum linear power density of 213mW/μm has been found for 808nm and 980nm laser, limited by thermal rollover. The tests were performed for duty cycles from 0.1% to 5% and pulse widths of 50μs and 100μm. Over 32W output power was reached for 150μm emitter at a 0.1 % duty cycle and 50μs pulse length. With the new diode laser technology 10mm bars with a 44% filling factor were produced. These laser bars, mounted on micro channel coolers, reached a maximum output power of 1000W. To our knowledge this is the highest power reported up to now for 980nm material with 100μs pulses and 0.1% duty cycle.

  9. Life prediction of 808nm high power semiconductor laser by accelerated life test of constant current stress

    NASA Astrophysics Data System (ADS)

    Yao, Nan; Li, Wei; Zhao, Yihao; Zhong, Li; Liu, Suping; Ma, Xiaoyu

    2015-10-01

    High power semiconductor laser is widely used because of its high transformation efficiency, good working stability, compact volume and simple driving requirements. Laser's lifetime is very long, but tests at high levels of stress can speed up the failure process and shorten the times to failure significantly. So accelerated life test is used here for forecasting the lifetime of 808nm CW GaAs/AlGaAs high power semiconductor laser that has an output power of 1W under 1.04A. Accelerated life test of constant current stress based on the Inverse Power Law Relationship was designed. Tests were conducted under 1.3A, 1.6A and 1.9A at room temperature. It is the first time that this method is used in the domestic research of laser's lifetime prediction. Applying Weibull Distribution to describe the lifetime distribution and analyzing the data of times to failure, characteristics lifetime's functional relationship model with current is achieved. Then the characteristics lifetime under normal current is extrapolated, which is 9473h. Besides, to confirm the validity of the functional relationship model, we conduct an additional accelerated life test under 1.75A. Based on this experimental data we calculated the characteristics lifetime corresponding to 1.75A that is 171h, while the extrapolated characteristics lifetime from the former functional relationship model is 162h. The two results shows 5% deviation that is very low and acceptable, which indicates that the test design is reasonable and authentic.

  10. A fundamental mode Nd:GdVO4 laser pumped by a large aperture 808 nm VCSEL

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Ma, J. L.; Yan, C. L.; Liu, G. J.; Ma, X. H.; Gong, J. F.; Feng, Y.; Wei, Z. P.; Wang, Y. X.; Zhao, Y. J.

    2013-05-01

    A fundamental mode Nd:GdVO4 laser pumped by a vertical cavity surface emitting laser (VCSEL) is experimentally demonstrated. The VCSEL has a circular output-beam which makes it easier for it to be directly coupled to a Nd:GdVO4 microcrystal. In our research, a large aperture 808 nm VCSEL, with a multi-ring-shaped aperture (MRSA) and an almost Gaussian-shaped far-field profile, is used as the pumping source. Experimental results for the Nd:GdVO4 laser pumped by the VCSEL are presented. The maximum output peak power of 0.754 W is obtained under a pump peak power of 1.3 W, and the corresponding opto-optic conversion efficiency is 58.1%. The average slope efficiency is 65.8% from the threshold pump power of 0.2 W to the pump power of 1.3 W. The laser beam quality factors are measured to be {M}x2=1.2 0 and {M}y2=1.1 5.

  11. Low-Level Laser Therapy (808 nm) Reduces Inflammatory Response and Oxidative Stress in Rat Tibialis Anterior Muscle After Cryolesion

    PubMed Central

    Assis, Lívia; Moretti, Ana I.S.; Abrahão, Thalita B.; Cury, Vivian; Souza, Heraldo P.; Hamblin, Michael R.; Parizotto, Nivaldo A.

    2012-01-01

    Background and Objective Muscle regeneration is a complex phenomenon, involving coordinated activation of several cellular responses. During this process, oxidative stress and consequent tissue damage occur with a severity that may depend on the intensity and duration of the inflammatory response. Among the therapeutic approaches to attenuate inflammation and increase tissue repair, low-level laser therapy (LLLT) may be a safe and effective clinical procedure. The aim of this study was to evaluate the effects of LLLT on oxidative/nitrative stress and inflammatory mediators produced during a cryolesion of the tibialis anterior (TA) muscle in rats. Material and Methods Sixty Wistar rats were randomly divided into three groups (n = 20): control (BC), injured TA muscle without LLLT (IC), injured TA muscle submitted to LLLT (IRI). The injured region was irradiated daily for 4 consecutive days, starting immediately after the lesion using a AlGaAs laser (continuous wave, 808 nm, tip area of 0.00785 cm2, power 30 mW, application time 47 seconds, fluence 180 J/cm2; 3.8 mW/cm2; and total energy 1.4 J). The animals were sacrificed on the fourth day after injury. Results LLLT reduced oxidative and nitrative stress in injured muscle, decreased lipid peroxidation, nitrotyrosine formation and NO production, probably due to reduction in iNOS protein expression. Moreover, LLLT increased SOD gene expression, and decreased the inflammatory response as measured by gene expression of NF-kβ and COX-2 and by TNF-α and IL-1β concentration. Conclusion These results suggest that LLLT could be an effective therapeutic approach to modulate oxidative and nitrative stress and to reduce inflammation in injured muscle. PMID:23001637

  12. The 808 nm Laser-Assisted Surgery as an Adjunct to Orthodontic Treatment of Delayed Tooth Eruption

    PubMed Central

    Seifi, Massoud; Vahid-Dastjerdi, Elahe; Ameli, Nazila; Badiee, Mohammad-Reza; Younessian, Farnaz; Amdjadi, Parisa

    2013-01-01

    Introduction: Failure of teeth to erupt from gingival tissues at usual developmental time is called delayed tooth eruption (DTE). Delayed tooth eruption lead to prolonged fixed orthodontic treatment and its eventual complications. The purpose of the present study was to evaluate the effect of laser-assisted (808 nm) surgical uncovering, on the tooth emergence and orthodontic treatment of DTE. Methods: A total of 16 orthodontic patients were included in this study and were equally assigned to an experimental and a control group. Subjects for experiment consisted of eight patients (6 girls and 2 boys) with a mean age of 14±0.9 years. All patients exhibited delayed second premolar eruption. The laser wavelength was 810 nm and it was set in a continuous wave mode at a power output of 1.6 watt with a 0.3-mm diameter fiber tip. When the target tissue was sufficiently anesthetized, the tip was directed at an angle of 10 to 20 degrees to the tissue (light contact mode); and was applied continuously for approximately 12 Seconds until an acceptable tooth exposure area was visible. The facial axis of the clinical crown (FACC) line represents the most prominent portion of the facial central lobe for premolars. All orthodontic brackets are aligned along this reference and are located on FA (Facial Axis) point. The standard for adequate tooth eruption was the accessibility of facial axis of the clinical crown (FACC) for bonding the brackets. Data gathered from the patients were statistically surveyed and compared by means of Tukey’s Test and Analysis of Variance (ANOVA). Results: All patients showed good gingival status, no significant bleeding during or immediately after the surgery, and acceptable level of healing after laser surgery. The biologic width of the teeth was preserved and no violation of this important periodontal parameter was observed. The average time for accessing the FA point in experimental group was 11±1.1 weeks and the mentioned period was increased to

  13. Effect of low-level laser therapy (808 nm) on skeletal muscle after endurance exercise training in rats

    PubMed Central

    Assis, Livia; Yamashita, Fernanda; Magri, Angela M. P.; Fernandes, Kelly R.; Yamauchi, Liria; Renno, Ana C. M.

    2015-01-01

    BACKGROUND: Low-level laser therapy (LLLT) has been demonstrated to be effective in optimizing skeletal muscle performance in animal experiments and in clinical trials. However, little is known about the effects of LLLT on muscle recovery after endurance training. OBJECTIVE: This study evaluates the effects of low-level laser therapy (LLLT) applied after an endurance training protocol on biochemical markers and morphology of skeletal muscle in rats. METHOD: Wistar rats were divided into control group (CG), trained group (TG), and trained and laser irradiated group (TLG). The endurance training was performed on a treadmill, 1 h/day, 5 days/wk, for 8 wk at 60% of the maximal speed reached during the maximal effort test (Tmax) and laser irradiation was applied after training. RESULTS: Both trained groups showed significant increase in speed compared to the CG. The TLG demonstrated a significantly reduced lactate level, increased tibialis anterior (TA) fiber cross-section area, and decreased TA fiber density. Myogenin expression was higher in soleus and TA muscles in both trained groups. In addition, LLLT produced myogenin downregulation in the TA muscle of trained animals. CONCLUSION: These results suggest that LLLT could be an effective therapeutic approach for stimulating recovery during an endurance exercise protocol. PMID:26647747

  14. The action of NIR (808nm) laser radiation and gold nanorods labeled with IgA and IgG human antibodies on methicillin-resistant and methicillin sensitive strains of Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Petrov, Pavel O.; Ratto, Fulvio; Centi, Sonia; Pini, Roberto; Tuchin, Valery V.

    2015-03-01

    The effect of NIR laser radiation (808 nm) on methicillin-sensitive and methicillin resistant strains of Staphylococcus aureus incubated with gold nanorods is studied. Nanorods having length of 44 (± 4) nm and diameter of 10 (± 3) nm with the absorption maximum in the NIR (800 nm), functionalized with human immunoglobulins IgA and IgG, were synthesized and used in the studies. The killing ability up to 97% of the microorganism populations by using this nanotechnology was shown.

  15. Temperature characteristic of 808nm VCSELs with large aperture

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Feng, Dawei; Hao, Yongqin; Wang, Yong; Yan, Changling; Lu, Peng; Li, Yang

    2015-03-01

    In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/°, the thermal resistance is 0.098°/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.

  16. 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.

  17. 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.

  18. Luminescence properties of SiO{sub x}N{sub y} irradiated by IR laser 808 nm: The role of Si quantum dots and Si chemical environment

    SciTech Connect

    Ruggeri, Rosa; Neri, Fortunato; Sciuto, Antonella; Privitera, Vittorio; Spinella, Corrado; Mannino, Giovanni

    2012-01-23

    We investigated optical, structural, and chemical properties of SiO{sub x}N{sub y} layers irradiated by CW IR laser during a time lapse of few milliseconds. We observed tunable photoluminescence signal at room temperature in the range 750-950 nm, without Si/SiO{sub 2} phase separation, depending on the IR laser power irradiation. Furthermore, no photoluminescence signal was recorded when the IR laser power density was high enough to promote phase separation forming Si quantum dots. By chemical analysis the source of the luminescence signal has been identified in a change of silicon chemical environment induced by IR laser annealing inside the amorphous matrix.

  19. 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%.

  20. Nd:YAG laser side pumped by diode laser arrays

    NASA Astrophysics Data System (ADS)

    Tan, Hua; Huang, Weiling; Zhou, Zhouyou; Wang, Hailin; Cao, Hongbing; Wang, Ying

    1999-09-01

    The major limitation of flashlamp-pumped solid-state lasers is the low overall efficiency. Replacing flashlamps with high power laser diodes allows an increase of system efficiency by over an order of magnitude. Because of the thermally induced stress fracture of the laser materials, power-scaling possibilities of end-pumped configurations are limited. Therefore side pump geometry has to be used for high power laser. The theory and the design of high power diode side-pumped Nd:YAG laser system is described. The Nd:YAG rod is side-pumped by diode laser arrays with wavelength at 808 nm. We analyze the result of our experiments and make some conclusions about the design of side-pumped laser.

  1. Efficient TEM(00)-mode operation of a laser-diode side-pumped Nd:YAG laser

    NASA Technical Reports Server (NTRS)

    Welford, D.; Rines, D. M.; Dinerman, B. J.

    1991-01-01

    The operation of a laser-diode side-pumped Nd:YAG laser with a novel pumping geometry that ensures efficient conversion of pump energy into the TEM(00) mode is reported. Of the 1064-nm output, 11.8 microJ of energy was obtained in a 200-microsec pulse with 64 microJ of pump energy at 808 nm. The overall conversion and slope efficiencies were 18 and 23 percent, respectively.

  2. 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.

  3. Diode-pumped Nd:YVO4-Nd:YLF blue laser at 488 nm by intracavity sum-frequency-mixing

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Zhang, X. H.; Li, C. L.; Zhao, Z. M.; Liu, Z. T.

    2010-07-01

    We report a laser architecture to obtain continuous-wave blue radiation at 488 nm. A 808 nm diodepumped the Nd:YVO4 crystal emitting at 914 nm. A part of the pump power was then absorbed by the Nd:YVO4 crystal. The remaining was used to pump the Nd:YLF crystal emitting at 1047 nm. Intracavity sum-frequency mixing at 914 and 1047 nm was then realized in a LBO crystal to reach the blue radiation. We obtained a continuous-wave output power of 514 mW at 488 nm with a pump laser diode emitting 19.6 W at 808 nm.

  4. Optimized Biasing of Pump Laser Diodes in a Highly Reliable Metrology Source for Long-Duration Space Missions

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya; Chang, Daniel; Erlig, Hernan

    2011-01-01

    Non Planar Ring Oscillator (NPRO) lasers are highly attractive for metrology applications. NPRO reliability for prolonged space missions is limited by reliability of 808 nm pump diodes. Combined laser farm aging parameter allows comparing different bias approaches. Monte-Carlo software developed to calculate the reliability of laser pump architecture, perform parameter sensitivity studies To meet stringent Space Interferometry Mission (SIM) Lite lifetime reliability / output power requirements, we developed a single-mode Laser Pump Module architecture that: (1) provides 2 W of power at 808 nm with >99.7% reliability for 5.5 years (2) consists of 37 de-rated diode lasers operating at -5C, with outputs combined in a very low loss 37x1 all-fiber coupler

  5. 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.

  6. High power diode lasers: technology and application in Europe

    NASA Astrophysics Data System (ADS)

    Behringer, Martin; Eberhard, Franz; Herrmann, Gerhard; Luft, Johann; Maric, J.; Morgott, Stefan; Philippens, Marc; Teich, W.

    2003-03-01

    The application field of high power semiconductor lasers is growing rapidly and covers e.g. solid state laser pumping, metal and plastic welding, hard and soft soldering, suface treatment and others. Preferably those applications are attractive, which do not require extremely high beam quality. We have investigated high power diode-laser bars from 808 nm to 980 nm. The scope of this presentation is on focusability and beam quality. For better beam shaping structures with reduced fill factor of 25% to 30% were developed. They were operated in continuous wave operation at power levels of up to 55 W. Tests indicate extrapolated lifetimes of more than 100,000 hours at 40 W at 980 nm cw and about 10,000 hours at 45 W - 50 W at 940 nm and 808 nm. Monolithically stacked NonostacksR were investigated. Operation up to 100°C with excellent lifetimes could be demonstrated. New concepts and applications for low mode number high power diode lasers like tapered laser bars are presented. Examples for various current areas of interest in European research facilities will be given.

  7. 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.

  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. Diode-pumped Nd:GAGG-LBO laser at 531 nm

    NASA Astrophysics Data System (ADS)

    Zou, J.; Chu, H.; Wang, L. R.

    2012-03-01

    We report a green laser at 531 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 1062 nm Nd:GAGG laser under in-band diode pumping at 808 nm. A LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 933 mW of cw output power at 531 nm is achieved. The fluctuation of the green output power was better than 3.5% in the given 4 h.

  10. Nd3+-sensitized NaLuF4 luminescent nanoparticles for multimodal imaging and temperature sensing under 808 nm excitation

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Zhang, Peng; Yuan, Qinghai; Xu, Xia; Lei, Pengpeng; Liu, Xiuling; Su, Yue; Dong, Lile; Feng, Jing; Zhang, Hongjie

    2015-10-01

    In this paper, intense up- and down-conversion luminescence were successfully achieved in well designed and synthesized core-shell structured NaLuF4:Gd/Yb/Er@NaLuF4:Yb@NaLuF4:Nd/Yb@NaLuF4 nanoparticles (NPs) simultaneously under 808 nm continuous-wave laser excitation. The morphologies, luminescent properties and energy transfer mechanism of the nanoparticles were studied in detail. By employing this design, multimodal imaging performance including near-infrared down-conversion optical imaging and X-ray computed tomography (CT) imaging were realized in one kind of NPs. Furthermore, the 808 nm excited optical temperature sensing property of the synthesized NPs was realized in a wide temperature range by monitoring the intensities of up- and down-conversion luminescence. This study provides a novel platform based on lanthanide fluoride nanoparticles for multifunctional imaging and temperature sensing in one system.In this paper, intense up- and down-conversion luminescence were successfully achieved in well designed and synthesized core-shell structured NaLuF4:Gd/Yb/Er@NaLuF4:Yb@NaLuF4:Nd/Yb@NaLuF4 nanoparticles (NPs) simultaneously under 808 nm continuous-wave laser excitation. The morphologies, luminescent properties and energy transfer mechanism of the nanoparticles were studied in detail. By employing this design, multimodal imaging performance including near-infrared down-conversion optical imaging and X-ray computed tomography (CT) imaging were realized in one kind of NPs. Furthermore, the 808 nm excited optical temperature sensing property of the synthesized NPs was realized in a wide temperature range by monitoring the intensities of up- and down-conversion luminescence. This study provides a novel platform based on lanthanide fluoride nanoparticles for multifunctional imaging and temperature sensing in one system. Electronic supplementary information (ESI) available: Fig. S1-S5. See DOI: 10.1039/c5nr04889c

  11. Analysis of 808nm centered optical parametric chirped pulse amplifier based on DKDP crystals

    NASA Astrophysics Data System (ADS)

    Sun, Meizhi; Cui, Zijian; Kang, Jun; Zhang, Yanli; Zhang, Junyong; Cui, Ying; Xie, Xinglong; Liu, Cheng; Liu, Dean; Zhu, Jianqiang; Lin, Zunqi

    2015-08-01

    The non-collinear phase-matching in Potassium Dideuterium Phosphate (DKDP) crystal is analyzed in detail with signal pulse of center wavelength at 808 nm and pump pulse of wavelength at 526.5 nm. By numerical analysis, parametric bandwidths for various DKDP crystals of different deuteration level are presented. In particularly for DKDP crystals of 95% deuteration level, the optimal non-collinear angles, phase-matching angles, parametric bandwidths, walk-off angles, acceptance angles, efficiency coefficients, gain and gain bandwidths are provided based on the parameter concepts. Optical parametric chirped pulse amplifier based on DKDP crystal is designed and the output characteristics are simulated by OPA coupled wave equations for further discuss. It is concluded that DKDP crystals higher than 90% deuteration level can be utilized in ultra-short high power laser systems with compressed pulses broader than 30fs. The disadvantage is that the acceptance angles are small, increasing the difficulty of engineering regulation.

  12. Effect of near-infrared diode laser and indocyanine green to treat infections on different wound models

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Yuksel, Sahru; Gulsoy, Murat

    2014-05-01

    The emergence of antibiotic resistant bacteria causes significant increase in deaths due to wound infections around the world. Nowadays, it could be impossible to find appropriate antibiotics to treat some bacterial strains, especially multidrug resistant types. The aim of this study is to use photodynamic therapy that destroys these kinds of bacteria with the interaction of Indocyanine green (ICG) and 808-nm diode laser. In this study, antibacterial Photodynamic Therapy technique that we call ICG-IR Laser PDT was applied on antibiotic-resistant strains of Staphylococcus aureus that infected two different types of wound model (excisional and abrasion wound model) in vivo. Wistar albino rats were used to create animal wound models. Excisional or abrasion wounds were formed on the dorsal skin of the rats. They were infected with Staphylococcus aureus. 300 mW and 500 mW of 808-nm diode laser were applied on the wounds for 30 minutes and 15 minutes of exposure duration, respectively. ICG concentrations applied topically were 500, 1000, 1500 and 2000 μg/ml. Then the tissue was dissected properly and homogenized in buffer solution. From this solution, bacterial cell count was determined by serial dilution method. 1-2 log reduction in viable cell count was observed after these applications. The temperature increase in the tissue was between 6-8°C during these applications. From these findings, it was understood that this method with 808-nm and ICG is promising but it must be improved by further dosimetry studies.

  13. 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.

  14. Laser diode protection circuit

    SciTech Connect

    Burgyan, L.; Hand, W.L.

    1990-05-08

    This patent describes a method for protecting a laser diode included within an electro-optical circuit. It comprises: the laser diode, a DC bias supply for supplying forward conduction current to the laser diode to cause it to emit light energy at a predetermined quiescent operating point, and an RF amplifier means for supplying an RF amplitude of an analog modulating signal to the laser diode for modulating the intensity of the emitted light energy about the quiescent operating point thereof, the method including providing a very high impedance to the laser diode during its nominal operating conditions about the quiescent point and, sensing an instantaneous amplitude of the RF amplitude modulating signal to detect amplitude surges therein, and responding to the sensing means by removing forward conduction current from the laser diode during the sense amplitude surges int he RF amplitude of the analog modulating signal, thereby causing the laser diode to reduce emission of light energy to a safe level.

  15. CW light sources at the 589 nm sodium D2 line by sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Lu, J.; Xu, L. J.; Sun, G. C.; Zhao, Z. M.; Gao, X.; Lin, J. Q.

    2010-10-01

    We present a laser architecture to obtain continuous-wave (CW) light sources at the 589 nm sodium D2 line. A 808 nm diode-pumped a Nd:YLiF4 (Nd:YLF) crystal emitting at 1053 nm. A part of the pump power was then absorbed by the Nd:YLF crystal. The remaining was used to pump a Nd:YAG crystal emitting at 1338 nm. Intracavity sum-frequency mixing at 1053 and 1338 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 235 mW at 589 nm with a pump laser diode emitting 17.8 W at 808 nm.

  16. Diode-pumped quasi-three-level Nd:GdV O4-Nd:YAG sum-frequency laser at 464 nm

    NASA Astrophysics Data System (ADS)

    Lu, Jie

    2014-04-01

    We report a laser architecture to obtain continuous-wave (cw) blue radiation at 464 nm. A 808 nm diode pumped a Nd:GdV O4 crystal emitting at 912 nm. A part of the pump power was then absorbed by the Nd:GdV O4 crystal. The remainder was used to pump a Nd:YAG crystal emitting at 946 nm. Intracavity sum-frequency mixing at 912 and 946 nm was then realized in a LiB3O5 (LBO) crystal to produce blue radiation. We obtained a cw output power of 1.52 W at 464 nm with a pump laser diode emitting 18.4 W at 808 nm.

  17. An efficient continuous-wave 591 nm light source based on sum-frequency mixing of a diode pumped Nd:GdVO4-Nd:CNGG laser

    NASA Astrophysics Data System (ADS)

    Zhao, Y. D.; Liu, J. H.

    2013-08-01

    We report a laser architecture to obtain continuous-wave (CW) yellow-orange light sources at the 591 nm wavelength. An 808 nm diode pumped a Nd:GdVO4 crystal emitting at 1063 nm. A part of the pump power was then absorbed by the Nd:CNGG crystal. The remaining pump power was used to pump a Nd:CNGG crystal emitting at 1329 nm. Intracavity sum-frequency mixing at 1063 and 1329 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 494 mW at 591 nm with a pump laser diode emitting 17.8 W at 808 nm.

  18. Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry.

    PubMed

    Bednařík, Antonín; Tomalová, Iva; Kanický, Viktor; Preisler, Jan

    2014-10-17

    Here we present a novel coupling of thin-layer chromatography (TLC) to diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). DLTV is a new technique of aerosol generation which uses a diode laser to induce pyrolysis of a substrate. In this case the cellulose stationary phase on aluminum-backed TLC sheets overprinted with black ink to absorb laser light. The experimental arrangement relies on economic instrumentation: an 808-nm 1.2-W continuous-wave infrared diode laser attached to a syringe pump serving as the movable stage. Using a glass tubular cell, the entire length of a TLC separation channel is scanned. The 8-cm long lanes were scanned in ∼35 s. The TLC - DLTV ICP MS coupling is demonstrated on the separation of four cobalamins (hydroxo-; adenosyl-; cyano-; and methylcobalamin) with limits of detection ∼2 pg and repeatability ∼15% for each individual species. PMID:25193171

  19. Fabrication of High power, High-Efficiency Linear Array Diode Lasers by Pulse Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Zhang, Jing; Li, Hui; Qu, Yi; Bo, Baoxue

    2006-09-01

    InGaAlAs/AlGaAs/GaAs double-quantum-well (DQW) linear array diode lasers with asymmetric wide waveguide have been successfully fabricated by pulse anodic oxidation upon molecular beam epitaxy material growth. High-efficiency and high-power quasi-continuous-wave (QCW) output has been realized at 808 nm wavelength. The threshold current and slope efficiency of the prepared high-fill-factor QCW devices are 24 A and 1.25 A/W, respectively, and a maximum wall-plug efficiency of 51% has been achieved.

  20. Catastrophic optical mirror damage in diode lasers monitored during single-pulse operation

    NASA Astrophysics Data System (ADS)

    Ziegler, Mathias; Tomm, Jens W.; Reeber, David; Elsaesser, Thomas; Zeimer, Ute; Larsen, Henning E.; Petersen, Paul M.; Andersen, Peter E.

    2009-05-01

    Catastrophic optical mirror damage (COMD) is analyzed for 808 nm emitting diode lasers in single-pulse operation in order to separate facet degradation from subsequent degradation processes. During each pulse, nearfield and thermal images are monitored. A temporal resolution better than 7 μs is achieved. The thermal runaway process is unambiguously related to the occurrence of a "thermal flash." A one-by-one correlation between nearfield, thermal flash, thermal runaway, and structural damage is observed. The single-pulse excitation technique allows for controlling the propagation of the structural damage into the cavity. We propose this technique for the analysis of early stages of COMD.

  1. 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.

  2. Diode-pumped Nd:YVO4 laser emitting at 1074 nm based on the 4 F 3/2-4 I 11/2 transition

    NASA Astrophysics Data System (ADS)

    Ma, Z. Y.; Li, C. L.; Liang, W.; Wang, J. G.

    2011-09-01

    We report a diode-pumped Nd:YVO4 laser emitting at 1074 nm, based on the 4 F 3/2-4 I 11/2 transition, generally used for a 1064 nm emission. A power of 323 mW at 1074 nm has been achieved in continuouswave (CW) operation with a fiber-coupled laser diode emitting 18.2 W at 808 nm. Intracavity second-harmonic generation in CW mode has also been demonstrated with a power of 18 mW at 537 nm by using a LiB3O5 (LBO) nonlinear crystal.

  3. Generation of neutral atomic beams utilizing photodetachment by high power diode laser stacks.

    PubMed

    O'Connor, A P; Grussie, F; Bruhns, H; de Ruette, N; Koenning, T P; Miller, K A; Savin, D W; Stützel, J; Urbain, X; Kreckel, H

    2015-11-01

    We demonstrate the use of high power diode laser stacks to photodetach fast hydrogen and carbon anions and produce ground term neutral atomic beams. We achieve photodetachment efficiencies of ∼7.4% for H(-) at a beam energy of 10 keV and ∼3.7% for C(-) at 28 keV. The diode laser systems used here operate at 975 nm and 808 nm, respectively, and provide high continuous power levels of up to 2 kW, without the need of additional enhancements like optical cavities. The alignment of the beams is straightforward and operation at constant power levels is very stable, while maintenance is minimal. We present a dedicated photodetachment setup that is suitable to efficiently neutralize the majority of stable negative ions in the periodic table. PMID:26628128

  4. 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).

  5. In vivo 808 nm image-guided photodynamic therapy based on an upconversion theranostic nanoplatform

    NASA Astrophysics Data System (ADS)

    Liu, Xiaomin; Que, Ivo; Kong, Xianggui; Zhang, Youlin; Tu, Langping; Chang, Yulei; Wang, Tong Tong; Chan, Alan; Löwik, Clemens W. G. M.; Zhang, Hong

    2015-09-01

    A new strategy for efficient in vivo image-guided photodynamic therapy (PDT) has been demonstrated utilizing a ligand-exchange constructed upconversion-C60 nanophotosensitizer. This theranostic platform is superior to the currently reported nanophotosensitizers in (i) directly bonding photosensitizer C60 to the surface of upconversion nanoparticles (UCNPs) by a smart ligand-exchange strategy, which greatly shortened the energy transfer distance and enhanced the 1O2 production, resulting in the improvement of the therapeutic effect; (ii) realizing in vivo NIR 808 nm image-guided PDT with both excitation (980 nm) and emission (808 nm) light falling in the biological window of tissues, which minimized auto-fluorescence, reduced light scatting and improved the imaging contrast and depth, and thus guaranteed noninvasive diagnostic accuracy. In vivo and ex vivo tests demonstrated its favorable bio-distribution, tumor-selectivity and high therapeutic efficacy. Owing to the effective ligand exchange strategy and the excellent intrinsic photophysical properties of C60, 1O2 production yield was improved, suggesting that a low 980 nm irradiation dosage (351 J cm-2) and a short treatment time (15 min) were sufficient to perform NIR (980 nm) to NIR (808 nm) image-guided PDT. Our work enriches the understanding of UCNP-based PDT nanophotosensitizers and highlights their potential use in future NIR image-guided noninvasive deep cancer therapy.A new strategy for efficient in vivo image-guided photodynamic therapy (PDT) has been demonstrated utilizing a ligand-exchange constructed upconversion-C60 nanophotosensitizer. This theranostic platform is superior to the currently reported nanophotosensitizers in (i) directly bonding photosensitizer C60 to the surface of upconversion nanoparticles (UCNPs) by a smart ligand-exchange strategy, which greatly shortened the energy transfer distance and enhanced the 1O2 production, resulting in the improvement of the therapeutic effect; (ii

  6. High-power multi-beam diode laser transmitter for a flash imaging lidar

    NASA Astrophysics Data System (ADS)

    Holmlund, Christer; Aitta, Petteri; Kivi, Sini; Mitikka, Risto; Tyni, Lauri; Heikkinen, Veli

    2013-10-01

    VTT Technical Research Centre of Finland is developing the transmitter for the "Flash Optical Sensor for TErrain Relative NAVigation" (FOSTERNAV) multi-beam flash imaging lidar. FOSTERNAV is a concept demonstrator for new guidance, navigation and control (GNC) technologies to fulfil the requirements for landing and docking of spacecraft as well as for navigation of rovers. This paper presents the design, realisation and testing of the multi-beam continuous-wave (CW) laser transmitter to be used in a 256x256 pixel flash imaging lidar. Depending on the target distance, the lidar has three operation modes using either several beams with low divergence or one single beam with a large divergence. This paper describes the transmitter part of the flash imaging lidar with focus on the electronics and especially the laser diode drivers. The transmitter contains eight fibre coupled commercial diode laser modules with a total peak optical power of 32 W at 808 nm. The main requirement for the laser diode drivers was linear modulation up to a frequency of 20 MHz allowing, for example, low distortion chirps or pseudorandom binary sequences. The laser modules contain the laser diode, a monitoring photodiode, a thermo-electric cooler, and a thermistor. The modules, designed for non-modulated and low-frequency operation, set challenging demands on the design of the drivers. Measurement results are presented on frequency response, and eye diagrams for pseudo-random binary sequences.

  7. 808 nm driven Nd3+-sensitized upconversion nanostructures for photodynamic therapy and simultaneous fluorescence imaging.

    PubMed

    Wang, Dan; Xue, Bin; Kong, Xianggui; Tu, Langping; Liu, Xiaomin; Zhang, Youlin; Chang, Yulei; Luo, Yongshi; Zhao, Huiying; Zhang, Hong

    2015-01-01

    The in vivo biological applications of upconversion nanoparticles (UCNPs) prefer excitation at 700-850 nm, instead of 980 nm, due to the absorption of water. Recent approaches in constructing robust Nd(3+) doped UCNPs with 808 nm excitation properties rely on a thick Nd(3+) sensitized shell. However, for the very important and popular Förster resonance energy transfer (FRET)-based applications, such as photodynamic therapy (PDT) or switchable biosensors, this type of structure has restrictions resulting in a poor energy transfer. In this work, we have designed a NaYF4:Yb/Ho@NaYF4:Nd@NaYF4 core-shell-shell nanostructure. We have proven that this optimal structure balances the robustness of the upconversion emission and the FRET efficiency for FRET-based bioapplications. A proof of the concept was demonstrated for photodynamic therapy and simultaneous fluorescence imaging of HeLa cells triggered by 808 nm light, where low heating and a high PDT efficacy were achieved. PMID:25406514

  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 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.

  10. 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.

  11. Diode Laser in Minor Oral Surgery: A Case Series of Laser Removal of Different Benign Exophytic Lesions

    PubMed Central

    Sotoode, Somaye Mazarei; Azimi, Somayyeh; Taheri, Sayed Alinaghi; Asnaashari, Mohammad; Khalighi, Hamidreza; Rahmani, Somayeh; Jafari, Soudeh; Elmi Rankohi, Zahra

    2015-01-01

    Introduction: The role of laser in conservative management of oral disease is well established. Laser procedures are common in the fields of oral surgery, implant dentistry, endodontic, and periodontic therapy. Case: This case series describes the use of diode laser for the excision of oral exophytic lesions. All the patients attended the oral medicine department of Shahid Beheshti University of Medical Sciences, Tehran, Iran. Criteria in patient selection were accessibility to lesions, patient fear from blade surgery, aesthetics, and probability of bleeding. An informed consent was filled by every patient. All of the lesions were completely excised under local anaesthesia by diode laser with 300 μm-fibre tip, 808 nm continuous wavelength and 3-3.5 W power for 3×60 seconds (Dr Smile, Italia). During surgery, the fibre tip was in contact with lesions. No analgesics were prescribed to the patients. The patients were followed for the first, second, and forth week after treatment. Conclusion: The lesions could be excised using the diode laser. This procedure was a quick clinical technique without bleeding. PMID:26464782

  12. A Diode Laser gas Extraction System for Heating Minerals for Geochronology

    NASA Astrophysics Data System (ADS)

    Foeken, J. P.; Stuart, F. M.; Persano, C.; Vilbert, D.

    2005-12-01

    Diode lasers, in comparison to Ar ion and Nd:YAG lasers, are compact, and cheap to purchase and maintain. We have developed a 25 W diode laser (808 nm) system for He extraction from minerals primarily for (U-Th)/He chronometry. The laser beam is delivered via a 600 μm fibre cable and focused using a binocular microscope. Temperatures necessary for He release from apatite and zircon encapsulated in Pt foil are attained by heating to 0.5 W and 1-1.5 W using a defocused beam. Analysis of 11 fragments from two different Durango apatite crystals yield (U-Th)/He ages of 32.8 +/- 0.7 Ma (1s). Five aliquots of apatite grains from 97MR22 (California Institute of Technology internal standard) yields ages of 4.5 +/- 0.5 Ma. The (U-Th)/He ages, and U/Th ratios are well within the published ages for these minerals. In order to test the diode laser for other geochronological and isotope applications we have heated various un-encapsulated crystals. The diode laser couples well with optically opaque minerals (e.g. hornblende, biotite, muscovite, garnet) and basalt groundmass. Heating and partial melting typically occurs at less than 4 W using a defocused beam. Coupling with muscovite, plagioclase, and semi-transparent sanidine required laser power of 5-10 W to initiate melting. Heating of near-transparent sanidine did not produce partial melting even at laser power in excess of 20 W. These results are consistent with other visible/near-infra red lasers and suggests that diode lasers offer a cheap, small, low-maintenance alternative for 40Ar/39Ar chronology and stable isotope studies.

  13. Design of diode-pumped solid-state laser applied in laser fuses

    NASA Astrophysics Data System (ADS)

    Deng, FangLin; Zhang, YiFei

    2005-04-01

    The function of laser fuzes which are parts of certain weapon systems is to control the blasting height of warheads. Commonly the battle environment these weapon systems are confronted with is very complicated and the tactical demand for them is very rigor, so laser fuzes equipped for them must fulfill some special technical requirements, such as high repetition rate, long ranging scope, etc. Lasers are one of key components which constitute fuze systems. Whether designed lasers are advanced and reasonable will determine whether laser fuzes can be applied in these weapon systems or not. So we adopt the novel technology of diode-pumped solid-state laser (DPSSL) to design lasers applied in fuzes. Nd:YVO4 crystal is accepted as gain material, which has wide absorption band and large absorption efficient for 808nm pumping laser. As warhead's temperature is usually very high, wider absorption band is beneficial to reduce the influence of temperature fluctuation. Passive Q-switching with Cr4+:YAG is used to reduce the power consumption farthest. Design the end-pumped microchip sandwich-architecture to decrease lasers' size and increase the reliability, further it's advantageous to produce short pulses and increase peak power of lasers. The designed DPSSL features small size and weight, high repetition rate and peak power, robustness, etc. The repetition rate is expected to reach 1 kHz; peak power will exceed 300 kW; pulse width is only 5 ns; and divergence angle of laser beams is less than 5 mrad. So DPSSL is suitable for laser fuzes as an emitter.

  14. Diode Laser Arrays

    NASA Astrophysics Data System (ADS)

    Botez, Dan; Scifres, Don R.

    1994-08-01

    This book provides a comprehensive overview of the fundamental principles and applications of semiconductor diode laser arrays. All of the major types of arrays are discussed in detail, including coherent, incoherent, edge- and surface-emitting, horizontal- and vertical-cavity, individually addressed, lattice- matched and strained-layer systems. The initial chapters cover such topics as lasers, amplifiers, external-cavity control, theoretical modeling, and operational dynamics. Spatially incoherent arrays are then described in detail, and the uses of vertical-cavity surface emitter and edge-emitting arrays in parallel optical-signal processing and multi-channel optical recording are discussed. Researchers and graduate students in solid state physics and electrical engineering studying the properties and applications of such arrays will find this book invaluable.

  15. Fiber coupling of high-power diode laser stack for direct polycarbonate processing

    NASA Astrophysics Data System (ADS)

    Vidal, E.; Quintana, I.; Azkorbebeitia, U.; Mendez, E.; Viera, G.; Galán, M.; Otaduy, D.

    2010-02-01

    We present a novel optical system for fiber coupling of a commercial high power diode laser stack and the application of this laser system to transmission welding of engineering thermoplastics. The diode laser stack is made up of two 20% fill factor bars, emitting at 808 nm and with a total maximum output power of 120W CW. The stack was collimated using FSAC micro-optics lenses in the fast and slow axis, with a full angle divergence of <4mrad and <25mrad respectively. The optical design and simulations were carried out using ZEMAX®. Based on the design we built an optical set up, which is divided in two subsystems. The first one collimates the laser beam in order to achieve the best focus and couple it into the 400μm core fiber with NA0.22 and 70% efficiency. The second subsystem is designed for beam conformation after the fiber output, using collimation and beam shaping to have a Gaussian beam profile on the work piece. The laser system was applied to study the welding of polycarbonate plastics, based on the effects of selected welding parameters on the seam geometry and surface integrity. The quality of the spot welding has been analyzed obtaining welded seams with a mean diameter about 500-600μm, preserving the good technological properties of the thermoplastic considered in this work. The results show that we have successfully developed a novel laser system which is highly efficient for thermoplastics processing.

  16. Laser diode array and transmission optics

    NASA Technical Reports Server (NTRS)

    Kwon, Jin H.

    1989-01-01

    Information on laser diode array and transmission optics is given in viewgraph form. Information is given on coherent combining of laser diode arrays, amplification through a laser diode array, the far field pattern of a laser diode transmitter, and beam diameter at receiver vs. transmission distance.

  17. Efficiency optimization and analysis of 808nm VCSELs with a full electro-thermal-optical numerical model

    NASA Astrophysics Data System (ADS)

    Engelhardt, Andreas P.; Kolb, Johanna S.; Roemer, Friedhard; Weichmann, Ulrich; Moench, Holger; Witzigmann, Bernd

    2015-03-01

    A high electro-optical conversion efficiency of a VCSEL (Vertical-Cavity Surface-Emitting Lasers) is one of the key requirements for their application in high power systems for heating, illumination and pumping applications. The substantial amount of degrees of freedom in the epitaxial and structural design of a VCSEL demands numerical guidance in form of technology computer aided design (TCAD) modeling for a straight forward and successful optimization of the devices. We set up a full electro-thermal optical model for the simulation of VCSEL devices. The electro-thermal part of the simulation follows a drift-diffusion model complemented by a customized, energy resolved, semi-classical carrier capture theory in the QW regions. Optical modes, eigensolutions of the vectorial electromagnetic wave equation, stem from a finite element vectorial solver. The electro-thermal and optical models are linked via the photon-rate equation using QW gain spectra (screened Hartree-Fock approximation) and iterated to self-consistency in a Gummel-type iteration scheme. For comparison and calibration, experimental reference data was extracted from oxide-confined, top-emitting VCSEL devices with an emission wavelength of 808 nm. Our simulations are in good agreement with the electro-optical characteristics of the experimental reference. With the calibrated, microscopic model, routes of design adjustment for efficiency optimization are explored. Exemplarily, the maximum VCSEL efficiency of the simulated reference design increases by 10% (absolute) when free hole absorption is switched off. Accordingly, with the combination of an electro-thermal and optical description, a balancing of the tradeoffs of pDBR doping towards reduced free carrier absorption results in a noteworthy efficiency improvement which is validated with experimental data.

  18. Unstable resonator diode laser

    SciTech Connect

    Clark, G.L.

    1988-04-19

    In a semiconductor diode laser, a structure is described comprising: a generally planar active layer, across which a forward bias voltage is applied, cladding layers adjacent to the active layer, to confine light in a direction perpendicular to the active layer, and first and second facets; in which the first facet is curved to present a concave part-cylindrical reflective surface toward the active layer, and in which the second facet includes a curved portion presenting a convex part-cylindrical reflective surface toward the active layer and a planar portion that is non-reflective. The curvatures of the two curved surfaces have axes of curvature that are approximately perpendicular to the active layer, the curvatures being selected to form an unstable resonator, in which light is confined in a particular sense by the cladding layers and from which energy is out-coupled through the planar portion of the second facet.

  19. 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.

  20. Biophotonic effect of diode laser irradiance on tensile strength of diabetic rats.

    PubMed

    Lau, Pik Suan; Bidin, Noriah; Krishnan, Ganesan; Nassir, Zaleha; Bahktiar, Hazri

    2015-04-01

    Low-energy laser irradiance at certain wavelengths is able to stimulate the tissue bio-reaction and enhance the healing process. Collagen deposition is one of the important aspects in healing process because it can increase the strength of the skin. This study was designed to examine the biophotonic effect of irradiance on collagen production of diabetic wound in rat model. The tensile strength of skin was employed as a parameter to describe the wound. Diabetic rat models were induced by streptozotocin via intravenous injection. Skin-breaking strength was measured using an Instron tensile test machine. The experimental animals were treated with 808-nm diode laser at two different powers-0.1 and 0.5 W/cm(2)-and 30, 60, and 120 s for each session. The tensile strength was optimized after treated with high-power diode laser. The photostimulation effect was revealed by accelerated healing process and enhanced tensile strength of wound. Laser photostimulation on tensile strength in diabetic wound suggests that such therapy facilitates collagen production in diabetic wound healing. PMID:25260140

  1. Catastrophic optical mirror damage in diode lasers monitored during single pulse operation

    NASA Astrophysics Data System (ADS)

    Tomm, Jens W.; Ziegler, Mathias; Elsaesser, Thomas; Larsen, Henning E.; Petersen, Paul M.; Andersen, Peter E.; Clausen, Sønnik; Zeimer, Ute; Fendler, David

    2010-02-01

    The catastrophic optical mirror damage (COMD) effect is analyzed for 808 nm emitting diode lasers in single-pulse operation. During each single pulse, both nearfield of the laser emission and thermal image of the laser facet are monitored with cameras being sensitive in the respective spectral regions. A temporal resolution in the μs-range is achieved. The COMD is unambiguously related to the occurrence of a 'thermal flash' detected by thermal imaging. A one-by-one correlation between emission nearfield, 'thermal flash', thermal runaway, and structural damage is observed. As a consequence of the single-pulse-excitation technique, the propagation of 'dark bands' as observed in photo- or cathodoluminescence maps in the plane of the active region from the front facet is halted after the first pulse. Because of the rapidness of the thermal runaway, we propose the single-pulse technique for testing the facet stability and the intentional preparation of early stages of COMD; even for diode lasers that regularly fail by other mechanisms.

  2. Efficient 1061 and 1329 nm laser emission of Nd:CNGG lasers under 885 nm diode pumping into the emitting level

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Jiang, H. L.; Ni, T. Y.; Zhang, T. Y.; Tao, Z. H.; Zeng, Y. H.

    2011-03-01

    We report an efficiency Nd:CNGG laser operating at 1061 and 1329 nm, respectively, direct pumped by a diode laser at 885 nm for the first time to our knowledge. The maximum outputs of 4.5 and 2.9 W, at 1061 and 1329 nm, respectively, are obtained in a 6-mm-thick 0.5 at % Nd:CNGG crystal with 13.5 W of absorbed pump power at 885 nm, leading to a high slope efficiency with respect to the absorbed pump power of 32.2 and 22.1%. Under traditional pumping at 808 nm, the maximum outputs of 3.9 and 2.7 W, at 1061 and 1329 nm, respectively, are obtained with 15.4 W of absorbed pump power, corresponding to the slope efficiency with respect to the absorbed pump power of 25.2 and 17.9%.

  3. Intracavity optical parametric oscillator based on GTR-KTP driven by laser-diode end-pumped Q-switched Nd:YVO 4 laser

    NASA Astrophysics Data System (ADS)

    Yang, Jian-Fei; Zhang, Bai-Tao; Huang, Hai-Tao; He, Jing-Liang; Xu, Jin-Long; Zhao, Shuang; Yang, Xiu-Qin; Qiu, Gang; Liu, Zong-Kai

    2010-07-01

    An efficient, eye-safe, high-repetition-rate, single-resonant intracavity optical parameter oscillator, driven by a laser-diode (LD) end-pumped acousto-optically Q-switched Nd:YVO 4 laser, based on high gray-trace resistance KTiPO 4 (GTR-KTP), was demonstrated. With a pump power of 13.8 W and frequency repetition rate of 40 kHz, the maximum power of 1.72 W with pulse width of 2.09 ns at signal wavelength 1572 nm is obtained. The corresponding peak power and single pulse energy is calculated to be 21 kW and 43 μJ, respectively. And the conversion efficiency from incident pump power at 808 nm to output power at signal wavelength 1572 nm is about 12.5%. The output instability is measured only to be 1% within 1 h.

  4. Enhanced vbasis laser diode package

    SciTech Connect

    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.

  5. Diode-pumped laser research

    NASA Technical Reports Server (NTRS)

    Ramos-Izquierdo, L.; Bufton, J. L.; Chan, K.

    1988-01-01

    The Laboratory for Oceans is currently working on the development of compact laser diode array (LD) pumped Nd:YAG lasers for use in space-based altimetry and ranging. Laser diode-array pumping technology promises to increase the electrical to optical efficiency of solid state lasers by an order of magnitude with a lifetime increase of nearly three orders of magnitude relative to today's conventional flashlamp-pumped laser systems. The small size, efficiency, and ruggedness make LD-pumped solid state lasers ideal for space based applications. In an in-house RTOP effort, a novel multiple-pass LD-pumped Nd:YAG laser amplifier was designed and tested to increase the 100 microjoule output pulse energy of the Lightwave laser oscillator. Preliminary results have yielded a round trip amplifier gain of about 15 percent using 7 microjoule LD-pump energy. As a parallel activity, funding was recently obtained to investigate the possible use of custom made fiber optic arrays to obtain an efficient optical coupling mechanism between the emitting laser diode-arrays and the target solid state laser material. Fiber optic coupling arrays would allow for the easy manipulation of the spatial emitting pattern of the diode pump sources to match either an end or side pumping laser configuration.

  6. Effects of low intensity laser irradiation during healing of infected skin lesions in the rat

    NASA Astrophysics Data System (ADS)

    Nussbaum, Ethne L.; Lilge, Lothar; Mazzulli, Tony; Pritzker, Kenneth P.

    2006-02-01

    Purpose: To determine the effect of low intensity laser therapy (LILT) on healing of infected skin wounds in the rat. Methods: Wounds on the dorsum of Sprague-Dawley rats (14 per group) were inoculated or sham-inoculated with P. aeruginosa. Wounds were irradiated or sham-irradiated three times weekly from Day 1-19 using 635nm or 808nm diode lasers at radiant exposure of 1 or 20 J/cm2 delivered in continuous wave (CW) or at an intensity modulation frequency of 3800Hz. Wound area and bacterial growth were evaluated three times weekly. Results: CW 808 nm (1 and 20 J/cm2) irradiation generally delayed healing in acute wounds. However, from Day 10 onwards CW 808 nm (1 J/cm2 and 20 J/cm2) and 808 nm 3800 Hz (1 J/cm2) irradiation improved healing in inoculated wounds. Healing in acute wounds improved using 635 nm irradiation at low radiant exposure (1 J/cm2); however, using 635 nm irradiation at high radiant exposure (20 J/cm2) delayed healing. Bacterial balance in wounds was significantly altered using 635 nm (20 J/cm2) and CW 808 nm irradiation (1 and 20 J/cm2). Conclusion: Clearing wounds of normal flora was not associated with improved healing. Proliferation of staphylococcal species in wounds was associated with delayed healing.

  7. 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.

  8. Increasing depth penetration in biological tissue imaging using 808-nm excited Nd3+/Yb3+/Er3+-doped upconverting nanoparticles.

    PubMed

    Söderlund, Hugo; Mousavi, Monirehalsadat; Liu, Haichun; Andersson-Engels, Stefan

    2015-08-01

    Ytterbium (Yb 3+ )-sensitized upconverting nanoparticles (UCNPs) are excited at 975 nm causing relatively high absorption in tissue. A new type of UCNPs with neodymium (Nd 3+ ) and Yb 3+ codoping is excitable at a 808-nm wavelength. At this wavelength, the tissue absorption is lower. Here we quantify, both experimentally and theoretically, to what extent Nd 3+ -doped UCNPs will provide an increased signal at larger depths in tissue compared to conventional 975-nm excited UCNPs. PMID:26271054

  9. Next generation high-brightness diode lasers offer new industrial applications

    NASA Astrophysics Data System (ADS)

    Timmermann, Andre; Meinschien, Jens; Bruns, Peter; Burke, Colin; Bartoschewski, Daniel

    2008-02-01

    So far, diode laser systems could not compete against CO II-lasers or DPSSL in industrial applications like marking or cutting due to their lower brightness. Recent developments in high-brightness diode laser bars and beam forming systems with micro-optics have led to new direct diode laser applications. LIMO presents 400W output from a 200μm core fibre with an NA of 0.22 at one wavelength. This is achieved via the combination of newly designed laser diode bars on passive heat sinks coupled with optimized micro-optical beam shaping. The laser is water cooled with a housing size of 375mm x 265mm x 70mm. The applications for such diode laser modules are mainly in direct marking, cutting and welding of metals and other materials, but improved pumping of fibre lasers and amplifiers is also possible. The small spot size leads to extremely high intensities and therefore high welding speeds in cw operation. For comparison: The M2 of the fibre output is 70, which gives a comparable beam parameter product (22mm*mrad) to that of a CO II laser with a M2 of 7 because of the wavelength difference. Many metals have a good absorption within the wavelength range of the laser diodes (NIR, 808nm to 980nm), which permits the cutting of thin sheets of aluminium or steel with a 200W version of this laser. First welding tests show reduced splatters and pores owing to the optimized process behaviour in cw operation with short wavelengths. The availability of a top-hat profile proves itself to be advantageous compared to the traditional Gaussian beam profiles of fibre, solid-state and gas lasers in that the laser energy is evenly distributed over the working area. For the future, we can announce an increase of the output power up to 1200W out of a 200μm fibre (0.22 NA). This will be achieved by further sophistication and optimisation of the coupling technique and the coupling of three wavelengths. The beam parameter product will then remain at 22mm*mrad with a power density of 3.8 MW

  10. Thermal analysis in high power GaAs-based laser diodes

    NASA Astrophysics Data System (ADS)

    Xueqin, Gong; Shiwei, Feng; Yuan, Yue; Junwei, Yang; Jingwei, Li

    2016-04-01

    The thermal characteristics of 808 nm AlGaAs/GaAs laser diodes (LDs) are analyzed via electrical transient measurements and infrared thermography. The temperature rise and thermal resistance are measured at various input currents and powers. From the electrical transient measurements, it is found that there is a significant reduction in thermal resistance with increasing power because of the device power conversion efficiency. The component thermal resistance that was obtained from the structure function showed that the total thermal resistance is mainly composed of the thermal resistance of the sub-mount rather than that of the LD chip, and the thermal resistance of the sub-mount decreases with increasing current. The temperature rise values are also measured by infrared thermography and are calibrated based on a reference image, with results that are lower than those determined by electrical transient measurements. The difference in the results is caused by the limited spatial resolution of the measurements and by the signal being captured from the facet rather than from the junction of the laser diode. Project supported by the National Natural Science Foundation of China (Nos. 61376077, 61201046, 61204081).

  11. 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.

  12. 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.

  13. Optimisation of the parameters of a pump chamber for solid-state lasers with diode pumping by the optical boiler method

    NASA Astrophysics Data System (ADS)

    Kiyko, V. V.; Kislov, V. I.; Ofitserov, E. N.; Suzdal'tsev, A. G.

    2015-06-01

    A pump chamber of the optical boiler type for solid-state lasers with transverse laser diode pumping is studied theoretically and experimentally. The pump chamber parameters are optimised using the geometrical optics approximation for the pump radiation. According to calculations, the integral absorption coefficient of the active element at a wavelength of 808 nm is 0.75 - 0.8 and the relative inhomogeneity of the pump radiation distribution over the active element volume is 17% - 19%. The developed pump chamber was used in a Nd:YAG laser. The maximum cw output power at a wavelength of 1064 nm was ~480 W at the optical efficiency up to 19.6%, which agrees with theoretical estimates.

  14. Highly efficient continuous-wave intracavity frequency-doubled Nd:YVO4-LBO laser at 457 nm under diode pumping into the emitting level 4F3/2

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Yin, X. D.; Xia, J.; Zhang, A. F.; Lin, J. Q.

    2010-04-01

    The continuous-wave high efficiency laser emission of Nd:YVO4 at the fundamental wavelength of 914 nm and its 457 nm second harmonic obtained by intracavity frequency doubling with an LBO nonlinear crystal is investigated under pumping by diode laser at 880 nm into emitting level 4F3/2. 6.5 W at 457 nm with M 2=1.8 was obtained from a 5-mm-thick 0.4 at.% Nd:YVO4 laser medium and a 15-mm-long LBO nonlinear crystal in a Z-type cavity for 18.6 W absorbed pump power. An optical-to-optical efficiency with respect to the absorbed pump power was 0.35. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing level 4F5/2, are given in order to prove the advantages of the 880 nm wavelength pumping.

  15. A diode laser system for heating minerals for (U-Th)/He chronometry

    NASA Astrophysics Data System (ADS)

    Foeken, Jurgen P. T.; Stuart, Finlay M.; Dobson, Katherine J.; Persano, Cristina; Vilbert, David

    2006-04-01

    We have developed a diode laser (25 W, 808 nm) system for He extraction from minerals for (U-Th)/He chronometry. The laser beam is delivered via a 600 μm fiber cable and focused using a binocular microscope. Temperatures necessary for He release from apatite (500-600°C) and zircon (1100-1300°C) encapsulated in Pt-foil tubes are attained by heating to 0.5 W for 30 s and 1.25-2.5 W for 20 min, respectively, using a defocused beam. Heating at these powers does not result in measurable U and/or Th loss from apatite, as noted by the preservation of the distinct Th/U in multiple splits of two different Durango apatite crystals. Analyses of Durango and the California Institute of Technology internal standard apatite 97MR22 yield (U-Th)/He ages of 32.8 ± 1.8 Ma (1σ, n = 11) and 4.6 ± 0.5 (1σ, n = 5), respectively, well within accepted ages. The (U-Th)/He age and Th/U of five Fish Canyon Tuff zircon aliquots yield 29.3 ± 2.2 Ma (1σ) and 0.6 ± 0.03, respectively, and are indistinguishable from ages produced by resistance furnace He extraction. Heating of unencapsulated minerals shows that the diode laser couples well with optically opaque minerals (e.g., hornblende, biotite, muscovite, garnet) and basalt groundmass, suggesting that diode lasers offer a cheap, small, low-maintenance alternative to Nd:YAG and Ar ion lasers for 40Ar/39Ar, cosmogenic noble gas, and stable isotope studies.

  16. Sub-80 femtosecond pulses generation from a diode-pumped mode-locked Nd:Ca3La2(BO3)4 disordered crystal laser.

    PubMed

    Ma, Jie; Pan, Zhongben; Cai, Huaqiang; Yu, Haohai; Zhang, Huaijin; Shen, Deyuan; Tang, Dingyuan

    2016-04-01

    We experimentally demonstrated a diode-pumped sub-80 fs Nd:Ca3La2(BO3)4 disordered crystal laser. Pumping by an 808 nm fiber coupled laser diode, stable continuous-wave mode-locked pulses as short as 79 fs were achieved with a semiconductor saturable absorber mirror (SESAM). The ultrashort pulses had a repetition rate of ∼98.9  MHz at the central wavelength of about 1068 nm. To the best of our knowledge, this is the first demonstration of sub-100 fs pulses and the shortest mode-locked pulses generated from the Nd3+-doped crystal lasers. PMID:27192242

  17. Chalcogenide glass microsphere laser.

    PubMed

    Elliott, Gregor R; Murugan, G Senthil; Wilkinson, James S; Zervas, Michalis N; Hewak, Daniel W

    2010-12-01

    Laser action has been demonstrated in chalcogenide glass microsphere. A sub millimeter neodymium-doped gallium lanthanum sulphide glass sphere was pumped at 808 nm with a laser diode and single and multimode laser action demonstrated at wavelengths between 1075 and 1086 nm. The gallium lanthanum sulphide family of glass offer higher thermal stability compared to other chalcogenide glasses, and this, along with an optimized Q-factor for the microcavity allowed laser action to be achieved. When varying the pump power, changes in the output spectrum suggest nonlinear and/or thermal effects have a strong effect on laser action. PMID:21165022

  18. IC Fabrication Methods Improve Laser Diodes

    NASA Technical Reports Server (NTRS)

    Miller, M.; Pickhardt, V.

    1984-01-01

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

  19. Low-cost 7 mW CW 355-nm diode-pumped intracavity frequency-tripled microchip laser

    NASA Astrophysics Data System (ADS)

    Aubert, Nicolas; Georges, Thierry; Chauzat, Corinne; Le Bras, Raymond; Féron, Patrice

    2006-02-01

    Low noise CW milliWatt scale UV lasers are needed for many analysis applications in the semiconductor and the biological fields. Intracavity tripling has been widely used to improve the UV output power of Q-switched or modelocked lasers, but no efficient diode-pumped CW UV laser was ever reported. One of the key to success is the use of a monolithic laser structure which both eliminates the birefringence interference issue and facilitates the single frequency operation. The monolithic structure is obtained by optically contacting crystals. It does not require any alignment, reduces the manufacturing cost and improves reliability. The optimization of the amplifying medium and doubling and tripling crystals involves as many parameters as pump absorption, thermal lens, cavity length, 1064 nm mode size, walk-off, acceptance angles, polarizations, phases... The interplay between these parameters will be discussed. Finally, several amplifying media (Nd:YAG and Nd:YVO 4), doubling crystals (KTP, KNbO 3, BBO, BiBO and LBO) and tripling crystals (BBO, BiBO, LBO) were tested. With a 2.4W 808 nm diode pump, several configurations have led to low noise 355 nm single frequency operation exceeding 5 mW. We believe that this power can still be improved.

  20. Broad interband semiconductor laser diodes

    NASA Astrophysics Data System (ADS)

    Tan, Chee Loon

    A semiconductor laser is a diode device that emits light via stimulated emission. Conventionally, light emitted from a semiconductor laser is spatially coherent or narrowband. The fundamental mechanism of stimulated emission process in general leads only to a single wavelength emission. However, there are some lasers emit light with a broad spectrum or different distinct wavelength subjected to various operating conditions such as external grating configuration with semiconductor laser, diode-pumped self-Q-switch fiber laser, ultrashort pulse excitation, photonic crystal fiber, ultrabroadband solid-state lasers, semiconductor optical amplifier-based multiwavelength tunable fiber lasers, nonlinear crystal, broadband semiconductor laser etc. This type of broadband laser is vital in many practical applications such as optical telecommunications, spectroscopy measurement, imaging technology, etc. Recently, an ultra-broadband semiconductor laser that utilizes intersubband optical transitions via quantum cascade configuration has been realized. Laser action with a Fabry-Perot spectrum covering all wavelengths from 6 to 8 microm simultaneously is demonstrated with this approach. More recently, broadband emission results from interband optical transitions via quantum-dot/dash nanostructures have been demonstrated in a simple p-i-n laser diode structure. To date, this latest approach offers the simplest design by proper engineering of quantized energy states as well as utilizing the high inhomogeneity of the dot/dash nanostructures, which is inherent from self-assembled growth technology. In this dissertation, modeling of semiconductor InGaAs/GaAs quantum-dot broadband laser utilizing the properties of inhomogeneous and homogeneous broadening effects on lasing spectral will be discussed, followed by a detail analysis of another type of broad interband semiconductor laser, which is InAs/InGaAlAs quantum-dash broadband laser. Based on the device characterization results

  1. 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.

  2. Schlieren with a laser diode source

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  3. 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.

  4. Grating rhomb diode laser power combiner

    NASA Technical Reports Server (NTRS)

    Minott, Peter O.; Abshire, James B.

    1987-01-01

    A compact device for spectrally combining many laser-diode beams into a single multi-wavelength beam has been developed for use in NASA's intersatellite communications programs. The prototype device combines seven 30 milliwatt beams into a single beam with 70 percent efficiency producing an output of approximately 150 milliwatts. All beams are coaxial and can be collimated with a single transmitter optical system. The combining technique is relatively insensitive to drifts in the laser-diode wavelength and provides both increased power output and laser-diode source redundancy. Combination of more than 100 laser-diodes producing an output greater than 5 watts appears feasible with this technique.

  5. High-power laser diodes at SCD: performance and reliability for defence and space applications

    NASA Astrophysics Data System (ADS)

    Risemberg, Shlomo; Karni, Yoram; Klumel, Genadi; Levy, Moshe; Berk, Yuri; Rech, Markus; Becht, Hubert; Frei, Bruno

    2009-05-01

    High Power Laser Diode Arrays developed and produced at SCD-SemiConductor Devices support a number of advanced defence and space programs. High efficiency and unsurpassed reliability at high operating temperatures are mandatory features for those applications. We report lifetime results of high power bar stacks, operating in QCW mode that rely on a field-proven design comprising Al-free wafer material technology and hard soldering robust packaging. A variety of packaging platforms have been implemented and tested at very harsh environmental conditions. Results include a long operational lifetime study totaling 20 billion pulses monitored in the course of several years for 808 nm QCW bar stacks.. Additionally, we report results of demanding lifetime tests for space qualification performed on these stacks at different levels of current load in a unique combination with operational temperature cycles in the range of -10 ÷60 °C. Novel solutions for highly reliable water cooled devices designed for operation in long pulses at different levels of PRF, are also discussed. The cooling efficiency of microchannel coolers is preserved while reliability is improved.

  6. 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.

  7. 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.

  8. 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.

  9. Hermetic diode laser transmitter module

    NASA Astrophysics Data System (ADS)

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

    1999-04-01

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

  10. 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)

  11. Diode-pumped CW molecular lasers

    NASA Astrophysics Data System (ADS)

    Wellegehausen, B.; Luhs, W.

    2016-05-01

    First continuous laser oscillation on many lines in the range of 533-635 nm on different transitions of Na2 and Te2 molecules has been obtained, optically pumped with common cw blue emitting InGaN diode lasers operating around 445 and 460 nm. Spectral narrowing of the diode laser is achieved with a beamsplitter and grating setup, allowing use of more than 50 % of the diode power. Operation conditions and properties of the laser systems are presented, and perspectives for the realization of compact low cost molecular lasers are discussed.

  12. Temperature dependent investigation of carrier transport, injection, and densities in 808 nm AlGaAs multi-quantum-well active layers for VCSELs

    NASA Astrophysics Data System (ADS)

    Engelhardt, Andreas P.; Kolb, Johanna S.; Römer, Friedhard; Weichmann, Ulrich; Moench, Holger; Witzigmann, Bernd

    2014-05-01

    The electro-optical efficiency of semiconductor vertical-cavity surface-emitting lasers (VCSELs) strongly depends on the efficient carrier injection into the quantum wells (QWs) in the laser active region. However, carrier injection degrades with increasing temperature which limits the VCSEL performance particularly in high power applications where self heating imposes high temperatures in operation. By simulation we investigate the transport of charge carriers in 808 nm AlGaAs multi-quantum-well active layers with special attention to the temperature dependence of carrier injection into the QWs. Experimental reference data was extracted from oxide-confined, top-emitting VCSELs. The transport simulations follow a drift-diffusion-model complemented by a customized, energy-resolved, semi-classical carrier capture theory. QW gain was calculated in the screened Hartree-Fock approximation with band structures from 8x8 k.p-theory. Using the gain data and by setting losses and the optical confinement factor according to experimental reference results, the appropriate threshold condition and threshold carrier densities in the QWs for a VCSEL are established in simulation for all transport considerations. With the combination of gain and transport model, we can explain experimental reference data for the injection efficiency and threshold current density. Our simulations show that the decreasing injection efficiency with temperature is not solely due to increased thermionic escape of carriers from the QWs. Carrier injection is also hampered by state filling in the QWs initiated from higher threshold carrier densities with temperature. Consequently, VCSEL properties not directly related to the active layer design like optical out-coupling or internal losses link the temperature dependent carrier injection to VCSEL mirror design.

  13. Diode lasers: From laboratory to industry

    NASA Astrophysics Data System (ADS)

    Nasim, Hira; Jamil, Yasir

    2014-03-01

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

  14. 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.

  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. Diode-pumped dysprosium laser materials

    NASA Astrophysics Data System (ADS)

    Bowman, S. R.; Condon, N. J.; O'Connor, S.; Rosenberg, A.

    2009-05-01

    We are investigating materials for direct blue solid-state lasers assuming UV excitation with GaN based laser diodes. Room temperature spectroscopy is reported relevant to a proposed quasi-three level laser from the 4F9/2 level in trivalent dysprosium. Modeling based on these measurements suggests this is a promising new laser transition.

  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. Physical limits of semiconductor laser operation: A time-resolved analysis of catastrophic optical damage

    SciTech Connect

    Ziegler, Mathias; Hempel, Martin; Tomm, Jens W.; Elsaesser, Thomas; Larsen, Henning E.; Andersen, Peter E.; Clausen, Soennik; Elliott, Stella N.

    2010-07-12

    The early stages of catastrophic optical damage (COD) in 808 nm emitting diode lasers are mapped by simultaneously monitoring the optical emission with a 1 ns time resolution and deriving the device temperature from thermal images. COD occurs in highly localized damage regions on a 30 to 400 ns time scale which is determined by the accumulation of excess energy absorbed from the optical output. We identify regimes in which COD is avoided by the proper choice of operation parameters.

  19. 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.

  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. 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.

  2. Laterally injected light-emitting diode and laser diode

    DOEpatents

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

    2015-06-16

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

  3. Very high brightness diode laser

    NASA Astrophysics Data System (ADS)

    Heinemann, Stefan; Lewis, Ben; Michaelis, Karsten; Schmidt, Torsten

    2012-03-01

    Multiple Single Emitter (MSE) modules allow highest power and highest brightness diode lasers based on standard broad area diodes. 12 single emitters, each rated at 11 W, are stacked in fast axis and with polarization multiplexing 200W are achieved in a fully collimated beam with a beam quality of 7mm*mrad in both axes. Volume Bragg Gratings (VBG) stabilize the wavelength and narrow the linewidth to less than 2nm. Dichroic mirrors are used for dense wavelength multiplexing of 4 channels within 12 nm. 400W are measured from a 0.2 mm fiber, 0.1 NA. Control and drive electronics are integrated into the 200 W platform and represent a basic building block for a variety of applications, such as a flexible turn key system comprising 12 MSE modules. An integrated beam switch directs the light in six 100 μm, or in one 0.2 mm and one 0.1 mm fiber. 800W are measured from the six 0.1 mm fibers and 700W from the 0.2 mm fiber. The technologies can be transferred to other wavelengths to include 793 nm and 1530 nm. Narrow line gratings and optimized spectral combining enable further improvements in spectral brightness and power.

  4. 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%.

  5. 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.

  6. A Diode Laser System for Synchronous Photoinjection

    SciTech Connect

    Poelker, M., Hansknecht, J.

    1997-12-31

    A laser system, which is composed of a gain switched diode seed laser and a single-pass diode optical amplifier, is used to drive the polarized electron source at Jefferson Lab. The system emits pulsed laser light synchronized to the accelerating cavity radio frequency (rf) at 1497 MHz or the third subharmonic, 499 MHz. The maximum average output power from the laser system is 500 mW and the optical pulse width is 60 to 80 ps. The laser system is compact and very reliable operating remotely for many days without attention.

  7. Sodium D2 resonance radiation based on intracavity sum-frequency-mixing laser operation in Nd:GdVO4-Nd:YLiF4 crystals

    NASA Astrophysics Data System (ADS)

    Li, J. H.; Liu, X. H.; Wu, J. B.; Zhang, X.

    2013-07-01

    We present a laser architecture to obtain continuous-wave orange-yellow radiation at 589 nm. A 808 nm diode-pumped the Nd:GdVO4 crystal emitting at 1341 nm. A part of the pump power was then absorbed by the Nd:GdVO4 crystal. The remainder was used to pump the Nd:YLiF4 (Nd:YLF) crystal emitting at 1053 nm. Intracavity sum-frequency-mixing at 1341 and 1053 nm was then realized in a LiB3O5 (LBO) crystal to produce orange-yellow radiation. We obtained a continuous-wave output power of 352 mW at 589 nm with a pump laser diode emitting 18.4 W at 808 nm.

  8. 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.

  9. 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.

  10. 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.

  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. 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.

  13. Composite resonator vertical cavity laser diode

    SciTech Connect

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

    1998-05-01

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

  14. NASA direct detection laser diode driver

    NASA Technical Reports Server (NTRS)

    Seery, B. D.; Hornbuckle, C. A.

    1989-01-01

    TRW has developed a prototype driver circuit for GaAs laser diodes as part of the NASA/Goddard Space Flight Center's Direct Detection Laser Transceiver (DDLT) program. The circuit is designed to drive the laser diode over a range of user-selectable data rates from 1.7 to 220 Mbps, Manchester-encoded, while ensuring compatibility with 8-bit and quaternary pulse position modulation (QPPM) formats for simulating deep space communications. The resulting hybrid circuit has demonstrated 10 to 90 percent rise and fall times of less than 300 ps at peak currents exceeding 100 mA.

  15. 885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

    NASA Technical Reports Server (NTRS)

    Yu, Anthony

    2012-01-01

    The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate (laser pulses, laser diodes such as the 885-nm LDA were used for pumping the Nd:YAG laser crystal. This pumping scheme has many potential advantages for improved reliability, efficiency, thermal management, contamination control, and mechanical flexibility. The advantages of using 885-nm pump diodes in Nd:YAG laser systems are numerous. The epitaxial structures of these 885-nm diodes are aluminum-free. There is a significant reduction in the thermal load generated from the Stokes shift or quantum defects. A Stokes shift is the energetic difference between the pump and laser photons. Pumping at a wavelength band closer to the lasing wavelength can reduce the thermal load by .30% compared to traditional pumping at 808 nm, and increase the optical- to-optical efficiency by the same factor. The slope efficiency is expected to increase with a reduction in the thermal load. The typical crystalline Nd:YAG can be difficult to produce with doping level >1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored

  16. 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

  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-based therapy device

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

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

  19. 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.

  20. 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.

  1. 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.

  2. High-brightness diode pump sources for solid-state and fiber laser pumping across 8xx-9xx nm range

    NASA Astrophysics Data System (ADS)

    Diamant, Ronen; Berk, Yuri; Cohen, Shalom; Klumel, Genady; Levy, Moshe; Openhaim, Yaki; Peleg, Ophir; Yanson, Dan; Karni, Yoram

    2011-06-01

    Advanced solid state laser architectures place increasingly demanding requirements on high-brightness, low-cost QCW laser diode pump sources, with custom apertures both for side and end rod pumping configurations. To meet this need, a new series of scalable QCW pump sources at 808nm and 940nm was developed. The stacks, available in multiple output formats, allow for custom aperture filling by varying both the length and quantity of stacked laser bars. For these products, we developed next-generation laser bars based on improved epitaxial wafer designs delivering power densities of 20W/mm of emission aperture. With >200W of peak QCW power available from a full-length 1cm bar, we have demonstrated power scaling to over 2kW in 10-bar stacks with 55% wall plug efficiency. We also present the design and performance of several stack configurations using full-length and reduced-length (mini) bars that demonstrate the versatility of both the bar and packaging designs. We illustrate how the ROBUST HEAD packaging technology developed at SCD is capable of accommodating variable bar length, pitch and quantity for custom rod pumping geometries. The excellent all-around performance of the stacks is supported by reliability data in line with the previously reported 20 Gshot space-grade qualification of SCD's stacks.

  3. Design of diode laser systems for solid state laser pumping

    NASA Astrophysics Data System (ADS)

    Michel, D.; Luethy, Willy A.; Weber, Heinz P.

    2003-11-01

    In contrast to flashlamps the emission of single stripe laser diodes is highly directional and can be focused rather easily to small spots, which gives access to very high pump intensities. Numerical arrangements are possible for transferring the pump radiation to the solid state laser media. In this paper the most important concepts of diode laser systems for pumping solid state lasers are summarized and described. Thereby the aim is to find the most efficient and powerful method for endpumping a Yb3+-double clad fiber.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

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

  8. 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.

  9. 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.

  10. Diode Laser Excision of Oral Benign Lesions

    PubMed Central

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

    2015-01-01

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

  11. High-Reliability Pump Module for Non-Planar Ring Oscillator Laser

    NASA Technical Reports Server (NTRS)

    Liu, Duncan T.; Qiu, Yueming; Wilson, Daniel W.; Dubovitsky, Serge; Forouhar, Siamak

    2007-01-01

    We propose and have demonstrated a prototype high-reliability pump module for pumping a Non-Planar Ring Oscillator (NPRO) laser suitable for space missions. The pump module consists of multiple fiber-coupled single-mode laser diodes and a fiber array micro-lens array based fiber combiner. The reported Single-Mode laser diode combiner laser pump module (LPM) provides a higher normalized brightness at the combined beam than multimode laser diode based LPMs. A higher brightness from the pump source is essential for efficient NPRO laser pumping and leads to higher reliability because higher efficiency requires a lower operating power for the laser diodes, which in turn increases the reliability and lifetime of the laser diodes. Single-mode laser diodes with Fiber Bragg Grating (FBG) stabilized wavelength permit the pump module to be operated without a thermal electric cooler (TEC) and this further improves the overall reliability of the pump module. The single-mode laser diode LPM is scalable in terms of the number of pump diodes and is capable of combining hundreds of fiber-coupled laser diodes. In the proof-of-concept demonstration, an e-beam written diffractive micro lens array, a custom fiber array, commercial 808nm single mode laser diodes, and a custom NPRO laser head are used. The reliability of the proposed LPM is discussed.

  12. GaAs laser diode pumped Nd:YAG laser

    NASA Technical Reports Server (NTRS)

    Conant, L. C.; Reno, C. W.

    1974-01-01

    A 1.5-mm by 3-cm neodymium-ion doped YAG laser rod has been side pumped using a GaAs laser diode array tuned to the 8680-A absorption line, achieving a multimode average output power of 120 mW for a total input power of 20 W to the final-stage laser diode drivers. The pumped arrangement was designed to take advantage of the high brightness of a conventional GaAs array as a linear source by introducing the pump light through a slit into a close-wrapped gold coated pump cavity. This cavity forms an integrating chamber for the pump light.

  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. Topics in Laser Spectroscopy: A semiconductor diode laser spectrometer for laser spectrochemistry

    NASA Astrophysics Data System (ADS)

    Lawrenz, J.; Niemax, K.

    The construction and the use of a single mode semiconductor diode laser spectrometer which can be tuned electronically controlled by temperature as well as by current is presented. The spectroscopic properties of this spectrometer including commercial semiconductor diode lasers of the AlGaAs/GaAs type operating in the wavelength range 735-860 nm are discussed. Examples of the application of diode laser spectrometers in laser spectrochemistry are given.

  16. Radiation Degradation Mechanisms in Laser Diodes

    NASA Technical Reports Server (NTRS)

    Johston, A. H.; Miyahira, T. F.

    2004-01-01

    Degradation mechanisms are investigated for laser diodes fabricated with different materials and wavelengths between 660 and 1550 nm. A new approach is developed that evaluates degradation below the laser threshold to determine the radiation-induced recombination density. This allows mechanisms at high injection, such as Auger recombination, to be separated from low-injection damage. New results show that AlGaInP lasers in the visible region are nearly an order of magnitude more resistant to radiation than devices fabricated with AlGaAs or AlGaAsP at longer wavelengths.

  17. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  19. 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.

  20. Integrated software package for laser diodes characterization

    NASA Astrophysics Data System (ADS)

    Sporea, Dan G.; Sporea, Radu A.

    2003-10-01

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

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

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.

    2000-01-01

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

  2. 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.

  3. Diode laser absorption sensors for combustion control

    NASA Astrophysics Data System (ADS)

    Xin, Zhou

    Combustion is the most widely used energy conversion technique in the world. Diode-laser absorption sensors offer significant opportunities and advantages for in situ measurements of multiple combustion parameters such as temperature and species concentration due to their high sensitivity, high spectral resolution, fast time response, robustness and non-intrusive character. The overall objective of this thesis is to design and develop time-resolved and real-time tunable diode laser sensors with the potential for combustion control. A crucial element in the design of a tunable-diode-laser optical-absorption-based sensor is the selection of optimum transitions. The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are developed. The development of this design-rule approach establishes a new paradigm to optimize tunable diode laser sensors for target applications. The water vapor spectrum in the 1-2 mum near-infrared region is systematically analyzed to find the best absorption transition pairs for sensitive measurement of temperature in the target combustion environment using a single tunable diode laser. Two sensors are developed in this work. The first sensor is a 1.8 mum, single-laser temperature sensor based on direct absorption scans. Successful time-resolved measurements in a variety of laboratory and practical devices are presented and used to identify potential improvements, and design rules for a second-generation sensor are developed based on the lessons learned. The second generation sensor is a 1.4 mum, single-laser temperature sensor using water vapor absorption detected by wavelength-modulation spectroscopy (WMS), which facilitates rapid data analysis and a 2 kHz real-time data rate in the combustion experiments reported here. Demonstration experiments in a heated cell and a forced Hencken burner confirm the sensitivity and accuracy of the sensors. The first application of TDL thermometry to a

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Outlook for diode lasers in medicine

    NASA Astrophysics Data System (ADS)

    Arons, Irving J.

    1994-07-01

    From their use in compact disc players and telecommunications to supermarket scanners, semi-conductor diode lasers now play an ever important role in medicine. Beginning in ophthalmology, as replacements for ion photocoagulator lasers, and used for several years outside of the United States for biostimulation of aching muscles and to treat chronic ulcers and wounds, high-powered diode systems are now finding their way into surgery and, in the future, will be used to activate photoactive dyes in the photodynamic therapy treatment of cancers, and perhaps to weld tissue to replace sutures. In this presentation, we attempt to cover the above applications as well as some newer ones, discussing the companies involved, the systems in use or under development, and some exciting new developments about to unfold.

  9. 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.

  10. 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.

  11. 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.

  12. Diode pumped alkali lasers (DPALs): an overview

    NASA Astrophysics Data System (ADS)

    Krupke, William F.

    2008-05-01

    The concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.

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

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2002-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2003-09-01

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

  15. 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.

  16. 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.

  17. 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.

  18. Role of diode lasers in metrology

    NASA Astrophysics Data System (ADS)

    Muthukrishnan, Kris

    1995-01-01

    The field of noncontact metrology is maturing as the video camera based and the laser probe based measurements are finding wide acceptance in the fields of semiconductor, micro electronics, disk drive, biomedical, chemical and aerospace industries. Some manufactures of conventional touch-probe based CMMs (Coordinated Measuring Machines) have started integrating video cameras and laser probes to compliment the measurements made by the touch-probe. The delicate nature of the parts and the extremely small feature sizes have fuelled the growing need for the multisensor technology to be incorporated into a single coordinate measuring machine. The laser probes compliment the video based metrology systems in providing the dynamic Z-height capabilities due to their faster data rate and increased resolution and accuracy. This paper highlights the pros and cons of different diode laser based sensors, drawn from the experience of applying them for measurements in different fields.

  19. Giant enhancement of upconversion emission in (NaYF₄:Nd³⁺/Yb³⁺/Ho³⁺)/(NaYF₄:Nd³⁺/Yb³⁺) core/shell nanoparticles excited at 808 nm.

    PubMed

    Huang, Xiaoyong

    2015-08-01

    In this work, colloidal hexagonal-phase (NaYF4:Nd3+/Yb3+/Ho3+)/(NaYF4:Nd3+/Yb3+) core/shell nanoparticles with intense visible upconversion emissions under 808-nm laser excitation were prepared. Compared with the core-only nanoparticles, a maximum 990-fold overall enhancement in the emission intensity of Ho3+ ions was achieved with the help of active-shell coating design, due to the significant increase in the near-infrared absorption and efficient energy transfer from Nd3+ primary-sensitizers to Ho3+ activators via Yb3+ bridging sensitizers. The luminescence-enhancement effect exhibited a strong dependence on the doping concentrations of NaYF4:Nd3+/Yb3+ active-shell. The optimal concentrations of Nd3+ and Yb3+ ions in the active-shell layer were found to be 30 and 5 mol. %, respectively. Moreover, the upconversion emission intensity of NaYF4:Nd3+/Yb3+-coated nanoparticles was about 2.5 times higher than the one coated with a NaYF4:Nd3+ active-shell. PMID:26258367

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

    NASA Technical Reports Server (NTRS)

    Silver, Joel A.; Kane, Daniel J.

    1999-01-01

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

  1. 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.

  2. 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

  3. 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.

  4. Laboratory diode laser spectroscopy in molecular planetary astronomy

    NASA Technical Reports Server (NTRS)

    Jennings, D. E.

    1988-01-01

    Infrared spectroscopy of planetary atmospheres is performed at high spectral resolution comparable to that in the laboratory. This requires that laboratory spectroscopy use the highest resolution and the most accurate techniques. Tunable diode laser spectroscopy can supply many of the spectroscopic parameters needed by astronomers. In particular, line positions, line strengths, and collisional line widths are measured with diode lasers, and these are often among the best values available. Diode laser spectra are complimentary to lower resolution, broader-coverage Fourier transform spectra. Certain procedures must be adopted, however, when using diode lasers, for determining their output characteristics and for calibrating each spectrum against quality references.

  5. Spectroscopy with Comb-Referenced Diode Lasers

    NASA Astrophysics Data System (ADS)

    Cich, Matthew; Lopez, Gary V.; Johnson, Philip M.; Sears, Trevor J.; McRaven, Christopher P.

    2010-06-01

    Extended cavity diode lasers have been stabilized by locking to components of an erbium-doped fiber laser-based frequency comb with a 250 MHz comb spacing centered at 1.5μ m. We find the Allan variance of the diode laser frequency relative to the single comb component to which it is locked is of the order of a few Hz. For the system as a whole, the absolute frequency accuracy is approximately 1.5 parts in 1012. In order to characterize the system more completely, we have recorded saturation dip absorption spectra of several transitions in the ν_1 + ν_3 combination band of acetylene near 6530 cm-1. We find good agreement with published absolute frequency measurements for these transitions, which have been used as secondary frequency standards in the past. Aside from extremely precise saturation dip measurements such as these, comb-stabilized lasers should permit excellent measurements of Doppler-broadened lineshapes, both to compare with theory and for analytical applications. Progress along these lines will be reported at the meeting. Acknowledgments: T. J. Sears gratefully acknowledges support from a Brookhaven National Laboratory program development grant that enabled this work and also support for research at Brookhaven National Laboratory which was carried out under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences.

  6. 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.

  7. Diode Laser Application in Soft Tissue Oral Surgery

    PubMed Central

    Azma, Ehsan; Safavi, Nassimeh

    2013-01-01

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

  8. 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

  9. 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.

  10. Improved multipass optics for diode laser spectroscopy

    SciTech Connect

    Hu, T.A.; Chappell, E.L.; Munley, J.T.; Sharpe, S.W. )

    1993-12-01

    Feedback between optical elements can be a major source of noise when trying to attain high sensitivity in infrared absorption experiments. We find that a conventional White-cell optical arrangement introduces etaloning fringes that modulate the peak-to-peak amplitude of our signals by 1 part in 16 666, a fractional change of 6[times]10[sup [minus]5]. Although relatively small, this noise'' is systematic and adds coherently with averaging, obscuring interesting absorption features. An easily constructed multipass optical system suited for performing high-resolution infrared spectroscopy in molecular beams is described. The design is based on a variation of the White cell and has been optimized for use with lead salt diode lasers. One of the key components in the improved design is the addition of an oscillating mirror for spoiling optical feedback generated by laser scatter and/or poor mode coupling of the laser to the multipass optics.

  11. Using a Diode Laser for Laser-Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Tran, Yang; Whitten, J. E.

    2001-08-01

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

  12. 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.

  13. Heat profiles of laser-irradiated nails

    NASA Astrophysics Data System (ADS)

    Paasch, Uwe; Nenoff, Pietro; Seitz, Anna-Theresa; Wagner, Justinus A.; Kendler, Michael; Simon, Jan C.; Grunewald, Sonja

    2014-01-01

    Onychomycosis is a worldwide problem with no tendency for self-healing, and existing systemic treatments achieve disease-free nails in only 35 to 76% of cases. Recently, treatment of nail fungus with a near-infrared laser has been introduced. It is assumed that fungal eradication is mediated by local heat. To investigate if laser treatment has the potential to eradicate fungal hyphae and arthrospores, laser heat application and propagation needs to be studied in detail. This study aimed to measure nail temperatures using real-time videothermography during laser irradiation. Treatment was performed using 808- and 980-nm linear scanning diode lasers developed for hair removal, enabling contact-free homogeneous irradiation of a human nail plate in one pass. Average and peak temperatures increased pass by pass, while the laser beam moved along the nail plates. The achieved mean peak temperatures (808 nm: 74.1 to 112.4°C, 980 nm: 45.8 to 53.5°C), as well as the elevation of average temperatures (808 nm: 29.5 to 38.2°C, 980 nm: 27.1 to 32.6°C) were associated with pain that was equivalent to that of hair removal procedures and was not significantly different for various wavelengths. The linear scanning laser devices provide the benefits of contact-free homogeneous heating of the human nail while ensuring adequate temperature rises.

  14. Efficiency of Nd laser materials with laser diode pumping

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    DOEpatents

    Holtom, Gary R.

    2008-11-25

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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

    NASA Astrophysics Data System (ADS)

    Zheng, Lihe; Taira, Takunori

    2016-03-01

    A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

  3. 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.

  4. 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.

  5. 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.

  6. Diode laser for abdominal tissue cauterization

    NASA Astrophysics Data System (ADS)

    Durville, Frederic M.; Rediker, Robert H.; Connolly, Raymond J.; Schwaitzberg, Steven D.; Lantis, John

    1999-06-01

    We have developed a new device to effectively and quickly stop bleeding. The new device uses a small, 5 W diode laser to heat-up the tip of a modified medical forceps. The laser beam is totally contained within a protective enclosure, satisfying the requirements for a Class I laser system, which eliminates the need to protective eyewear. The new device is used in a manner similar to that of a bipolar electrocautery device. After visual location, the bleeding site or local vessel(s) is grabbed and clamped with the tips of the forceps-like instrument. The laser is then activated for a duration of typically 5 sec or until traditional visual or auditory clues such as local blubbling and popping indicate that the targeted site is effectively cauterized. When the laser is activated, the tip of the instrument, thus providing hemostasis. The new device was evaluated in animal models and compared with the monopolar and bipolar electrocautery, and also with the recently developed ultrasound technology. It has new been in clinical trials for abdominal surgery since September 1997.

  7. 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.

  8. Digital control of diode laser for atmospheric spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  9. Photoluminescence excitation measurements using pressure-tuned laser diodes

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  10. 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.

  11. The effect of low-level laser irradiation on muscle tension and hardness compared among three wavelengths

    PubMed Central

    Kogure, Shinichi

    2013-01-01

    Background and Aims: It has been reported that low-level laser irradiation (LLLI) can influence muscle tissue by retarding attenuation of muscle tension. Since the efficacy of LLLI on the effects of muscle contraction remains unclear, we examined in an in vivo animal model whether LLLI affects both muscle tension and muscle hardness in a wavelength-dependent manner, using the rat gastrocnemius muscle. Material and Methods: Forty Sprague-Dawley adult rats were used. Under pentobarbital sodium anesthesia, their gastrocnemius muscle and tibial nerve were exteriorized. Diode LLLI systems delivering 3 wavelengths (405, 532, and 808 nm; 100 mW output) were used. Ten sets of tetanus (tetanic contractions) were delivered to the tibial nerve followed by a brief rest or LLLI for 15 s and an additional 7 sets of tetanus with an inter-stimulus interval of 5 min. The muscle tension and muscle hardness were measured with a tension transducer and hardness meter, respectively. Results: 405 nm LLLI did not influence either muscle tension or hardness. 532 nm LLLI significantly improved the maintenance of muscle tension compared with the 808 nm group (P<0.05). In contrast, 808 nm LLLI significantly improved the recovery from muscle hardness compared with the other groups (P<0.05). Conclusion: We conclude that LLLI has wavelength-dependent effects on the gastrocnemius muscle and LLLI at appropriate wavelengths and dosimetry offers potential in the treatment to relieve muscle tension or stiffness. PMID:24204094

  12. Optical detection of honeybees by use of wing-beat modulation of scattered laser light for locating explosives and land mines

    NASA Astrophysics Data System (ADS)

    Repasky, Kevin S.; Shaw, Joseph A.; Scheppele, Ryan; Melton, Christopher; Carsten, John L.; Spangler, Lee H.

    2006-03-01

    An instrument is demonstrated that can be used for optical detection of honeybees in a cluttered environment. The instrument uses a continuous-wave diode laser with a center wavelength of 808 nm and an output power of 28 mW as the laser transmitter source. Light scattered from moving honeybee wings will produce an intensity-modulated signal at a characteristic wing-beat frequency (170-270 Hz) that can be used to detect the honeybees against a cluttered background. The optical detection of honeybees has application in the biological detection of land mines and explosives, as was recently demonstrated.

  13. Tunable diode lasers for 3-30 micron infrared operation

    NASA Technical Reports Server (NTRS)

    Linden, K. J.

    1983-01-01

    The tunable diode laser is now widely used in high resolution infrared spectroscopy studies, taking into account laboratory and industrial applications. The present investigation is concerned with advances related to laser performance and reliability. The advances are the result of improvements in materials and device technologies. Reliability data for broad-area Pb(1-x)Sn(x)Se lasers are considered along with performance improvements in stripe-geometry lasers, laser performance at wavelengths above 25 microns, and laser performance at wavelengths below 4 microns. Attention is given to tunable Pb-salt infrared diode lasers, mesa-stripe geometry lasers of Pb(1-x)Sn(x)Se and PbS(1-x)Se(x), and long wavelength diode laser emission observed in both Pb(1-x)Sn(x)Te and Pb(1-x)Sn(x)Se.

  14. 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.

  15. 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…

  16. Evaluation of low-level laser therapy in the treatment of masticatory muscles spasticity in children with cerebral palsy.

    PubMed

    Santos, Maria Teresa Botti Rodrigues; Diniz, Michele Baffi; Gouw-Soares, Sheila Cynthia; Lopes-Martins, Rodrigo Alvaro Brandão; Frigo, Lucio; Baeder, Fernando Martins

    2016-02-01

    Spasticity is a motor disorder frequently present in individuals with cerebral palsy (CP). This study aimed to evaluate the effect of low-level laser therapy (LLLT) on the spasticity of the masseter and anterior temporal muscle fibers in children with CP over three weeks of intermittent laser exposures. The bite force (BF) of the masticatory muscles and the amplitude of mouth opening were evaluated before and after laser irradiation in 30 children with CP. Both sides of the masseter and temporalis muscles were irradiated with low-intensity diode laser pulses of 808-nm wavelength six times over three consecutive weeks. During the subsequent three weeks of postlaser exposures, although no laser treatment was applied, the evaluation parameters were measured and recorded. A significant improvement in the amplitude of mouth opening and a decrease in the BF were observed in the weeks following LLLT (P<0.05 ). However, by the sixth week post-LLLT, the BF and the amplitude of mouth opening reverted to values equivalent to those obtained before the first application of LLLT. Our investigation revealed low-level energy exposures from a 808-nm diode laser to be an effective short-term therapeutic tool. This method increased the amplitude of mouth opening and decreased the muscle tonus of children with spastic CP over a time course of three weeks of intermittent laser applications. PMID:26882450

  17. Evaluation of low-level laser therapy in the treatment of masticatory muscles spasticity in children with cerebral palsy

    NASA Astrophysics Data System (ADS)

    Santos, Maria Teresa Botti Rodrigues; Diniz, Michele Baffi; Gouw-Soares, Sheila Cynthia; Lopes-Martins, Rodrigo Alvaro Brandão; Frigo, Lucio; Baeder, Fernando Martins

    2016-02-01

    Spasticity is a motor disorder frequently present in individuals with cerebral palsy (CP). This study aimed to evaluate the effect of low-level laser therapy (LLLT) on the spasticity of the masseter and anterior temporal muscle fibers in children with CP over three weeks of intermittent laser exposures. The bite force (BF) of the masticatory muscles and the amplitude of mouth opening were evaluated before and after laser irradiation in 30 children with CP. Both sides of the masseter and temporalis muscles were irradiated with low-intensity diode laser pulses of 808-nm wavelength six times over three consecutive weeks. During the subsequent three weeks of postlaser exposures, although no laser treatment was applied, the evaluation parameters were measured and recorded. A significant improvement in the amplitude of mouth opening and a decrease in the BF were observed in the weeks following LLLT (P<0.05). However, by the sixth week post-LLLT, the BF and the amplitude of mouth opening reverted to values equivalent to those obtained before the first application of LLLT. Our investigation revealed low-level energy exposures from a 808-nm diode laser to be an effective short-term therapeutic tool. This method increased the amplitude of mouth opening and decreased the muscle tonus of children with spastic CP over a time course of three weeks of intermittent laser applications.

  18. 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.

  19. 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.

  20. Ball Lenses Collimate And Focus Diode-Laser-Array Beams

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1992-01-01

    Ball lenses used to collimate and focus pump light from array of diode lasers onto input face of solid-state laser. Experiments show ball lenses perform as well as, or better than, multiple-element lenses supplied heretofore as parts of commercial arrays of diode lasers. Offers advantages of relative simplicity and ease of fabrication, lower cost, lower weight, and less sensitivity to misalignment.

  1. A core-shell-shell nanoplatform upconverting near-infrared light at 808 nm for luminescence imaging and photodynamic therapy of cancer

    PubMed Central

    Ai, Fujin; Ju, Qiang; Zhang, Xiaoman; Chen, Xian; Wang, Feng; Zhu, Guangyu

    2015-01-01

    Upconversion nanoparticles (UCNPs) have been extensively explored for photodynamic therapy (PDT) and imaging due to their representative large anti-Stokes shifts, deep penetration into biological tissues, narrow emission bands, and high spatial-temporal resolution. Conventional UCNP-based PDT system, however, utilizes exitation at 980 nm, at which water has significant absorption, leading to a huge concern that the cell killing effect is from the irradiation due to overheating effect. Here we report an efficient nanoplatform using 808-nm excited NaYbF4:Nd@NaGdF4:Yb/Er@NaGdF4 core−shell−shell nanoparticles loaded with Chlorin e6 and folic acid for simultaneous imaging and PDT. At this wavelength, the absorption of water is minimized. High energy transfer efficiency is achieved to generate cytotoxic singlet oxygen. Our nanoplatform effectively kills cancer cells in concentration-, time-, and receptor-dependent manners. More importantly, our nanoplatform is still able to efficiently generate singlet oxygen beneath 15-mm thickness of muscle tissue but 980 nm excitation cannot, showing that a higher penetration depth is achieved by our system. These results imply that our nanoplatform has the ability to effectively kill intrinsic tumor or the center of large tumors through PDT, which significantly improves the anticancer efficacy using UCNP-based PDT system and broadens the types of tumors that could be cured. PMID:26035527

  2. 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

  3. 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.

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

    PubMed

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

    2015-08-01

    This paper presents results of cooperative efforts on development of a continuous wave Cs diode pumped alkali laser with moderate output power, which can be considered as a prototype of the commercial device. The developed system operates at 895 nm with output power about 4 W and slope efficiency 28%. Measured turn on time of this system from the standby mode is about a minute. PMID:26329171

  5. Lead-strontium-chalcogenide diode laser

    SciTech Connect

    Partin, D.L.

    1988-01-26

    A large optical cavity quantum well double heterojunction semiconductor infrared diode laser is described having an active region layer sandwiched between two contiguous layers of monocrystalline semiconductive material. The laser exhibits current carrier and optical confinement for its active region layer but also exhibits increased operating temperature due to close lattice matching of face centered cubic monocrystalline layers forming the double heterojunctions. The laser comprises a monocrystalline buffer layer of a given conductivity type lead salt semiconductor containing strontium, selenium that has an energy band gap greater than, an index of refraction lesser than, and a lattice constant substantially equal to predetermined values of the active region layer, a monocrystalline active region layer on the buffer layer of a lead salt semiconductor containing a pn junction that has the predetermined energy and gap, index of refraction and lattice constant, and a confinement layer on the active region layer an opposite conductivity type lead salt semiconductor containing lesser amounts and smaller proportions of strontium and selenium that has an energy band gap greater than, an index of refraction smaller than, and a lattice constant substantially equal to the predetermined values.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Laser balloon vascular welding using a dye-enhanced albumin solder

    NASA Astrophysics Data System (ADS)

    Ott, Beat; Zueger, Benno J.; Erni, Dominique; Banic, Andrej; Schaffner, Thomas; Weber, Heinz P.; Frenz, Martin

    2001-05-01

    Porcine posterior tibial arteries (n equals 50) and saphenous veins (n equals 32) have been welded end-to-end using an 808 nm diode laser combined with an indocyanine green enhanced albumin solder. For comparison, the same welding procedure has been performed with a Holmium:YAG laser without solder. Both lasers were running in continuous wave (cw) regime at a power limited below 1.2 W. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment. The balloon catheter simplified vessel handling and the tight vessel positioning prevented a solder penetration into the lumen. Standard histology revealed for both welding techniques a lateral tissue damage between 2 and 3 mm. The vessels welded with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure 457 +/- 200 mmHg) were independent of the welding technique used.

  11. 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.

  12. 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)

  13. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.

  14. 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.

  15. 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.

  16. LD-side-pumped Nd:YAG/BaWO4 intracavity Raman laser for anti-Stokes generation

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Cong, Zhenhua; Qin, Zengguang; Zhang, Xingyu; Wei, Wei; Wang, Weitao; Zhang, Yuangeng; Zhang, Huaijin; Yu, Haohai

    2014-07-01

    A diode-side-pumped actively Q-switched Nd:YAG/BaWO4 intracavity anti-Stokes Raman laser is demonstrated for the first time. The oscillation directions of the fundamental and the Stokes beams are separated at a phase-matching angle by introducing an additional coupled Raman cavity in the fundamental resonator. The highest 968 nm anti-Stokes output power of 0.94 mW is obtained with a 170 W 808 nm pumping power and a 7.5 kHz pulse repetition frequency. Meanwhile, the Stokes power obtained is 4.2 W.

  17. 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.

  18. 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

  19. GaN blue diode lasers: a spectroscopist's view

    NASA Astrophysics Data System (ADS)

    Leinen, H.; Glässner, D.; Metcalf, H.; Wynands, R.; Haubrich, D.; Meschede, D.

    We have characterized the spectroscopic properties of one of the first samples of blue-emitting diode lasers based on GaN. With such a laser diode operated inside a standard extended cavity arrangement we find a mode-hop free tuning range of more than 20 GHz and a linewidth of 10 MHz. Doppler-free spectroscopy on an indium atomic beam reveals the isotope shift between the two major indium isotopes as well as efficient optical pumping.

  20. 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.

  1. Green laser modules to fit laser projection out of your pocket

    NASA Astrophysics Data System (ADS)

    Steegmüller, U.; Kühnelt, M.; Unold, H.; Schwarz, T.; Schulz, R.; Illek, S.; Pietzonka, I.; Lindberg, H.; Schmitt, M.; Strauss, U.

    2008-02-01

    Among enabling key components for mobile laser projection, the green laser plays an outstanding role: We present green laser modules based on frequency doubled optically pumped semiconductor disk lasers. In these lasers with twofold conversion, from 808nm over 1060nm to 530nm, active semiconductor components and second harmonic generation have to be carefully optimized to realize good efficiency at moderate output powers. The concept was developed not only to meet power and efficiency targets, but also to provide simple operation and control by pump diode current. The latest concept targets green output powers of more than 50mW at wall plug efficiencies >7%, limiting total electrical power consumption to less than 1W. Consequent use of micro optical components allows for a package volume of less than 0.5cm 3.

  2. 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.

  3. 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

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

    SciTech Connect

    Augustoni, Arnold L.

    2004-10-01

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

  5. Diode-pumped Alexandrite ring laser for lidar applications

    NASA Astrophysics Data System (ADS)

    Munk, A.; Jungbluth, B.; Strotkamp, M.; Hoffmann, H.-D.; Poprawe, R.; Höffner, J.

    2016-03-01

    We present design and performance data of a diode-pumped Q-switched Alexandrite ring laser in the millijoule regime, which is longitudinally pumped by laser diode bar modules in the red spectral range. As a first step, a linear resonator was designed and characterized in qcw operation as well as in Q-switched operation. Based on these investigations, two separate linear cavities were set up, each with one Alexandrite crystal longitudinally pumped by one diode module. The two cavities are fused together and form a ring cavity which yields up to 6 mJ pulse burst energy in the qcw regime at 770 nm.

  6. Development and optimization of a diode laser for photodynamic therapy

    PubMed Central

    Lim, Hyun Soo

    2011-01-01

    Background and Aims: This study demonstrated the development of a laser system for cancer treatment with photodynamic therapy (PDT) based on a 635 nm laser diode. In order to optimize efficacy in PDT, the ideal laser system should deliver a homogeneous nondivergent light energy with a variable spot size and specific wavelength at a stable output power. Materials and Methods: We developed a digital laser beam controller using the constant current method to protect the laser diode resonator from the current spikes and other fluctuations, and electrical faults. To improve the PDT effects, the laser system should deliver stable laser energy in continuous wave (CW), burst mode and super burst mode, with variable irradiation times depending on the tumor type and condition. Results and Comments: The experimental results showed the diode laser system described herein was eminently suitable for PDT. The laser beam was homogeneous without diverging and the output power increased stably and in a linear manner from 10 mW to 1500 mW according to the increasing input current. Variation between the set and delivered output was less than 7%. Conclusions: The diode laser system developed by the author for use in PDT was compact, user-friendly, and delivered a stable and easily adjustable output power at a specific wavelength and user-set emission modes. PMID:24155529

  7. 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.

  8. 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.

  9. Laser diode arrays for naval reconnaissance

    NASA Astrophysics Data System (ADS)

    Holloway, John H., Jr.; Crosby, Frank J.; Petee, Danny A.; Suiter, Harold R.; Witherspoon, Ned H.

    2003-09-01

    The Airborne Littoral Reconnaissance Technologies (ALRT) Project has demonstrated a nighttime operational minefield detection capability using commercial off-the-shelf high-power Laser Diode Arrays (LDAs). Historically, optical aerial detection of minefields has primarily been limited to daytime operations but LDAs promise compact and efficient lighting to allow for enhanced reconnaissance operations for future mine detection systems. When combined with high-resolution intensified imaging systems, LDAs can illuminate otherwise unseen areas. Future wavelength options will open the way for active multispectral imaging with LDAs. The Coastal Systems Station working for the Office of Naval Research on the ALRT project has designed, developed, integrated, and tested both prototype and commercial arrays from a Cessna airborne platform. Detailed test results show the ability to detect several targets of interest in a variety of background conditions. Initial testing of the prototype arrays, reported on last year, was completed and further investigations of the commercial versions were performed. Polarization-state detection studies were performed, and advantageous properties of the source-target-sensor geometry noted. Current project plans are to expand the field-of-view coverage for Naval exercises in the summer of 2003. This paper describes the test collection, data library products, array information, on-going test analysis results, and future planned testing of the LDAs.

  10. Airborne tunable diode laser measurements of formaldehyde

    NASA Astrophysics Data System (ADS)

    Fried, Alan; Wert, Bryan P.; Henry, Bruce; Drummond, James R.

    1999-09-01

    Accurate measurements of formaldehyde (CH 2O) in the atmosphere are essential to further our understanding of various atmospheric cycles involving hydrogen and carbon-containing species. Comparisons among independent measurements of this gas and between measurements and model calculations have raised numerous questions regarding the veracity of both endeavors. The present paper describes a long-term effort by our group to develop and employ tunable diode laser absorption spectroscopy (TDLAS) for highly accurate measurements of this gas on both ground-based and aircraft platforms. A highly sensitive and selective TDLAS system, which has successfully flown on three different aircraft campaigns, will be described. Many new hardware and software features, which have been implemented, now make it possible to detect ambient CH 2O concentrations as low as 55 parts-per-trillion employing a 20-s integration time. This paper will also discuss the many aspects associated with high accuracy and its verification, including a brief discussion of our aircraft sampling system and inlet surface effects.

  11. 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.

  12. 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.

  13. Laser transmission welding of Clearweld-coated polyethylene glycol terephthalate by incremental scanning technique

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Wang, A. H.; Weng, Z. K.; Xia, H. B.

    2016-06-01

    Transmission laser welding using Incremental Scanning Technique(TWIST) mode and conventional contour welding mode were adopted to investigate laser transmission welding of 0.5 mm thick PET plate. A 1064 nm fiber laser was used to weld PET at the (TWIST) mode, and an 808 nm diode laser was applied to conduct the conventional contour welding. The Clearweld coating was used as laser absorbing material. The influences of laser parameters (i.e. defocusing distance, distance between two circles) on the quality of weld seams were analyzed by optical microscopy. Moreover, geometry and shear strength of the weld zone were tested to optimize laser parameters. Additionally, the water vapor permeability (WVP) of weld seams was measured to test hermetical capacity. Results show that the shear strength and hermetic capacity of weld seam by TWIST mode are at the same level in comparison with that of the conventional contour welding.

  14. Diode-Pumped, Q-Switched, Frequency-Doubling Laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

    Experimental Q-switched, diode-pumped, intracavity-frequency-doubling laser generates pulses of radiation at wavelength of 532 nm from excitation at 810 nm. Principal innovative feature distinguishing laser from others of its type: pulsed operation of laser at pulse-repetition frequencies higher than reported previously. Folded resonator keeps most of second-harmonic radiation away from Q-switcher, laser crystal, and laser diodes. Folding mirror highly reflective at fundamental laser wavelength and highly transmissive at second-harmonic laser wavelength. By virtue of difference of about 0.6 percent between reflectivities in two polarizations at fundamental wavelength, folding mirror favors polarized oscillation at fundamental wavelength. This characteristic desirable for doubling of frequency in some intracavity crystals.

  15. All solid-state continuous-wave intracavity frequency-doubled Nd:LuVO4-LBO red laser at 671.5 nm

    NASA Astrophysics Data System (ADS)

    Jiang, Z. M.; Liang, W.; Chen, D. R.; Zhang, X. H.

    2011-01-01

    We report for the first time a efficient compact red laser at 671.5 nm generation by intracavity frequency doubling of a continuous wave laser operation of a diode direct pumped Nd:LuVO4 laser on the 4 F 3/2 → 4 I 13/2 transition at 1343 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an absorbed pump power of 16.2 W, as high as 4.3 W of continuous wave output power at 671.5 nm is achieved with 10-mm-long LBO. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing 4 F 5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.

  16. 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.

  17. Laser cleaning of oil spill on coastal rocks

    NASA Astrophysics Data System (ADS)

    Kittiboonanan, Phumipat; Rattanarojpan, Jidapa; Ratanavis, Amarin

    2015-07-01

    In recent years, oil spills have become a significant environmental problem in Thailand. This paper presents a laser treatment for controlled-clean up oil spill from coastal rocks. The cleaning of various types of coastal rocks polluted by the spill was investigated by using a quasi CW diode laser operating at 808 nm. The laser power was attempted from 1 W to 70 W. The result is shown to lead to the laser removal of oil spill, without damaging the underlying rocks. In addition, the cleaning efficiency is evaluated using an optical microscope. This study shows that the laser technology would provide an attractive alternative to current cleaning methods to remove oil spill from coastal rocks.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Light polarization experiments with a diode laser pointer

    NASA Astrophysics Data System (ADS)

    Benenson, Raymond E.

    2000-01-01

    Polarized light has many uses: glare reduction, stress analysis, microscope image enhancement, thin-film characterization, astronomy, saccharimetry, and atomic spectroscopy. Here we discuss introductory polarized light measurements in which a diode laser pointer replaces the more frequently used polarized He-Ne laser. A diode laser has been used in introductory optics experiments, and in a more advanced polarization-reflection experiment. Its strong collimated beam is completely polarized and, being free of infrared radiation, it permits Polaroid sheets to be used successfully with semiconductor detectors.

  4. Diode-pumped solid state laser for inertial fusion energy

    SciTech Connect

    Payne, S.A.; Krupke, W.F.; Orth, C.D.

    1994-11-01

    The authors evaluate the prospect for development of a diode-pumped solid-state-laser driver in an inertial fusion energy power plant. Using a computer code, they predict that their 1 GWe design will offer electricity at 8.6 cents/kW {center_dot} hr with the laser operating at 8.6% efficiency and the recycled power level at 31%. The results of their initial subscale experimental testbed of a diode-pumped solid state laser are encouraging, demonstrating good efficiencies and robustness.

  5. Management of chronic generalized periodontitis using diode laser

    PubMed Central

    Dixit, Santosh; Doshi, Yogesh; Shah, Mona Udayan; Dabholkar, Charuta Sadanand

    2016-01-01

    The aim of this study was to evaluate the effect of a diode laser with nonsurgical periodontal therapy on chronic periodontitis. The patient, a 37-year-old female, with chronic periodontitis reported to the private dental clinic. Her health history indicated that she had good general health. The periodontal examination included a gingival index and complete periodontal probing depth with William's graduated probe. She was treated with 940 nm diode laser and scaling and root planning. Assessment was done after 6 months following laser therapy; the probing depths improved; gain in clinical attachment levels; no inflammation; the tissue tone was good, showing increased stippling. PMID:27041846

  6. Narrow spectral width laser diode for metastable argon atoms pumping

    NASA Astrophysics Data System (ADS)

    Gao, Jun; Li, Bin; Wang, Xinbing; Zuo, Duluo

    2016-03-01

    Diode laser pump source with narrow emitting spectrum for optically pumped metastable rare gas laser (OPRGL) of argon was achieved by employing a complex external cavity coupled with volume Bragg grating (VBG). A commercially available c-mount laser diode with rated power of 6 W was used and studied in both the free running mode and VBG external cavity. The maximum output power of 3.9 W with FWHM less than 25 pm and peak wavelength locked around 811.53 nm was obtained from the VBG external cavity laser diode. Precise control of VBG temperature enabled fine tuning of the emission wavelength over a range of 450 pm. Future researches on OPRGL of argon will benefit from it.

  7. 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.

  8. 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.

  9. 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.

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  12. 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.

  13. 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.

  14. Spectra and broad-spectral laser operation of a disordered Nd:LiLa(MoO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Shan; Huang, Xinyang; Li, Bingxuan; Wei, Yong; Huang, Chenghui; Zhuang, Fengjiang; Chen, Weidong; Zhai, Suya; Zhang, Ge

    2013-06-01

    The crystal characteristics of a disordered Nd:LiLa(MoO4)2 laser crystal were investigated in detail, including its structure, absorption, emission and Raman scattering spectra. Laser operation, end-pumped by an 808 nm diode laser, has been demonstrated in both a concave-plano and plane-parallel resonator cavity. A broad-spectral dual-peak laser emission at 1061 nm and 1060 nm with a full width at half maximum of 2 nm was obtained in the experiment. A maximum output power of 267 mW was obtained in the concave-plano cavity. However, in the plane-parallel cavity, laser output of 381 mW was obtained, giving a slope efficiency of 14.5%. The results lay the groundwork for Raman, mode-locked and tunable laser applications generated by a Nd:LiLa(MoO4)2 laser crystal.

  15. 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.

  16. Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

    NASA Astrophysics Data System (ADS)

    Müller, André; Jensen, Ole B.; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E.; Petersen, Paul M.

    2011-12-01

    A simple and robust diode laser system emitting 1.28 W of green light suitable for pumping an ultrafast Ti:sapphire laser is presented. To classify our results, the diode laser is compared to a standard, commercially available diode pumped solid-state (DPSS) laser system pumping the same oscillator. When using our diode laser system, the optical conversion efficiencies from green to near-infrared light reduces to 75 % of the values achieved with the commercial pump laser. Despite this reduction the overall efficiency of the Ti:sapphire laser is still increased by a factor > 2 due to the superior electro-optical efficiency of the diode laser. Autocorrelation measurements show that pulse widths of less than 20 fs can be expected with an average power of 52 mW when using our laser. These results indicate the high potential of direct diode laser pumped Ti:sapphire lasers to be used in applications like retinal optical coherence tomography (OCT) or pumping of photonic crystal fibers for CARS (coherent anti-stokes Raman spectroscopy) microscopy.

  17. 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.

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

    PubMed Central

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

    2013-01-01

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

  19. 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.

  20. 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.

  1. Microchannel heatsinks for high average power laser diode arrays

    SciTech Connect

    Beach, R.; Benett, B.; Freitas, B.; Ciarlo, D.; Sperry, V.; Comaskey, B.; Emanuel, M.; Solarz, R.; Mundinger, D.

    1992-01-01

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

  2. 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.

  3. 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

  4. High duty cycle hard soldered kilowatt laser diode arrays

    NASA Astrophysics Data System (ADS)

    Klumel, Genady; Karni, Yoram; Oppenheim, Jacob; Berk, Yuri; Shamay, Moshe; Tessler, Renana; Cohen, Shalom

    2010-02-01

    High-brightness laser diode arrays operating at a duty cycle of 10% - 20% are in ever-increasing demand for the optical pumping of solid state lasers and directed energy applications. Under high duty-cycle operation at 10% - 20%, passive (conductive) cooling is of limited use, while micro-coolers using de-ionized cooling water can considerably degrade device reliability. When designing and developing actively-cooled collimated laser diode arrays for high duty cycle operation, three main problems should be carefully addressed: an effective local and total heat removal, a minimization of packaging-induced and operational stresses, and high-precision fast axis collimation. In this paper, we present a novel laser diode array incorporating a built-in tap water cooling system, all-hard-solder bonded assembly, facet-passivated high-power 940 nm laser bars and tight fast axis collimation. By employing an appropriate layout of water cooling channels, careful choice of packaging materials, proper design of critical parts, and active optics alignment, we have demonstrated actively-cooled collimated laser diode arrays with extended lifetime and reliability, without compromising their efficiency, optical power density, brightness or compactness. Among the key performance benchmarks achieved are: 150 W/bar optical peak power at 10% duty cycle, >50% wallplug efficiency and <1° collimated fast axis divergence. A lifetime of >0.5 Ghots with <2% degradation has been experimentally proven. The laser diode arrays have also been successfully tested under harsh environmental conditions, including thermal cycling between -20°C and 40°C and mechanical shocks at 500g acceleration. The results of both performance and reliability testing bear out the effectiveness and robustness of the manufacturing technology for high duty-cycle laser arrays.

  5. 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.

  6. 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.

  7. Arrangement for damping the resonance in a laser diode

    NASA Technical Reports Server (NTRS)

    Katz, J.; Yariv, A.; Margalit, S. (Inventor)

    1985-01-01

    An arrangement for damping the resonance in a laser diode is described. This arrangement includes an additional layer which together with the conventional laser diode form a structure (35) of a bipolar transistor. Therein, the additional layer serves as the collector, the cladding layer next to it as the base, and the active region and the other cladding layer as the emitter. A capacitor is connected across the base and the collector. It is chosen so that at any frequency above a certain selected frequency which is far below the resonance frequency the capacitor impedance is very low, effectively shorting the base to the collector.

  8. 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.

  9. High-efficiency side diode pumped breech mount laser ignition

    NASA Astrophysics Data System (ADS)

    Hardy, Christopher R.; Guo, Baoping; Myers, Michael J.; Myers, John D.

    2007-09-01

    Breech Mounted Lasers (BMLs) have been successfully used to demonstrate laser ignition of howitzer propellant charges including bag, stick, and the Modular Artillery Charge System (MACS). BMLs have been integrated and tested on many artillery systems, including the US Army's M109A6 Paladin, M198, M777 Light Weight, Crusader, and Non-Line-of-Sight Cannon (NLOS-C). Until now, these lasers have been relatively large and inefficient systems based on a flashlamp pumped Nd:YAG laser design. Modern vehicle platforms will require smaller, more efficient lasers that can operate under increased shock and vibration loads. Kigre's new DPSS (Diode Pumped Solid State) lasers appear to meet these requirements. In this work we provide an evaluation of HESP (High Efficiency Side Pumped) DPSS laser design and performance with regard to its application as a practical artillery laser ignition system.

  10. 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.

  11. Fiber laser at 2 μm for soft tissue surgery

    NASA Astrophysics Data System (ADS)

    Ghosh, Aditi; Pal, Debasis; Sen, Ranjan; Pal, Atasi

    2014-11-01

    Strong water absorption at 2 μm generated recent interest in lasers at this wavelength for soft tissue surgery. A fiber Bragg grating-based, all-fiber, continuous-wave, cladding pumped, thulium-doped fiber laser at 1.95 μm is configured. The thulium-doped active fiber with octagonal-shaped inner cladding is pumped at 808 nm (total power of 17 W) with six laser diodes through a combiner. The laser power of 3.3 W (after elimination of unabsorbed pump power through a passive fiber) with slope efficiency of 23% (against launched pump power) is achieved. The linear variation of laser power with pump offers scope of further power scaling.

  12. Characterization and development of an extended cavity tunable laser diode

    NASA Astrophysics Data System (ADS)

    Traptilisa, Fnu

    A laser diode emits a narrow range of frequencies. However, drifts in frequency occur over time due to many factors like changes in laser temperature, current, mechanical vibrations in the apparatus, etc. These frequency drifts make the laser unsuitable for experiments that require high frequency stability. We have used an atomic transition in rubidium as a frequency reference and used Doppler free saturated spectroscopy to observe the reference peak. We have designed an electronic locking circuit that operates the diode laser at a specific frequency. It keeps the laser at that frequency for a long period of time with very few or no drifts. We have constructed and characterized an extended cavity diode laser that costs significantly less than a commercial unit. It is much more compact with performance comparable to that of a commercial unit. It can be used in undergraduate and graduate optics laboratories where commercial units are cost prohibitive. The various components of the set-up are discussed, and the basic principles behind the function and operation of this versatile device are explained. We designed a servo loop filter circuit, which is used to stabilize the frequency of the laser to an atomic reference frequency. We also generated an error signal using a technique similar to the Pound Hall Drever technique and then feedback the error signal in the loop filter circuit.

  13. Method and system for homogenizing diode laser pump arrays

    DOEpatents

    Bayramian, Andy J

    2013-10-01

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

  14. 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%.

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

    NASA Astrophysics Data System (ADS)

    Green, Benjamin

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

  16. 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)

  17. Diode laser treatment for osteal and osteoarticular panaritium

    NASA Astrophysics Data System (ADS)

    Privalov, Valery A.; Krochek, Ivan V.; Lappa, Alexander V.; Poltavsky, Andrew N.; Antonov, Andrew A.

    2005-08-01

    Laser osteoperforation method, initially developed for treatment of osteomyelitis, was successfully applied to 66 patients with osteal and osteoarticular panaritium. The procedure consisted in perforation of the affected phalanx with diode laser radiation (wavelength 970nm; average power 10-12W; pulse mode 100/50 ms), delivered through quartz monofiber. Additional laser induced thermotherapy (power 2-3W; continuous mode) was fulfilled for persistent fistulas. In comparison with conventional surgery, laser osteoperforation provided faster pain relieve, edema dissipation, wound and fistula closure; good functional results; decreasing of disability cases number.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

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

    SciTech Connect

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

    2015-07-15

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

  5. Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

    PubMed

    Telford, William G

    2015-12-01

    Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes. PMID:25930008

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Electrically injected visible vertical cavity surface emitting laser diodes

    SciTech Connect

    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.

  11. Diode laser osteoperforation and its application to osteomyelitis treatment

    NASA Astrophysics Data System (ADS)

    Privalov, Valeriy A.; Krochek, Igor V.; Lappa, Alexander V.

    2001-10-01

    Laser osteoperforation, previously studied in experiment in rabbits at treatment for acute purulent osteomyelitis (Privalov V. et.al., SPIE Proc., v.3565., pp. 72-79), was applied in clinic to 36 patients with chronic purulent osteomyelitis and to 6 patients (children) with acute haematogenic osteomyelitis. Diode lasers of 805 and 980 nm wavelength were used. There was achieved full recovery in all acute cases, and stable remission in chronic cases during all the observation period (1 - 2.5 years).

  12. 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.

  13. SPECTRAL MEASUREMENTS OF GASEOUS SULFURIC ACID USING TUNABLE DIODE LASERS

    EPA Science Inventory

    Using a tunable diode laser spectrometer with a spectral resolution of about 10 to the -4 power/cm, the important central portions of the two infrared absorption bands of H2SO4 at 8.2 micrometers (1222/cm) and 11.3 micrometers (880/cm) have been scanned at low pressure (approxima...

  14. Diode-laser-based lidars: the next generation

    NASA Astrophysics Data System (ADS)

    Vujkovic-Cvijin, Pajo; Cooper, David E.; Van der Laan, Jan E.; Warren, Russell E.

    1999-10-01

    The work on the development of compact diode laser-based lidar systems at SRI International is reviewed. Two systems, a pseudorandom modulation lidar, and a mobile remote sensor for natural gas pipeline leak detection are described in detail, and experimental results are presented. Methods to enhance signal detection by digital filtering are also reviewed.

  15. Molecular oxygen detection using frequency modulation diode laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Wang, Liang-Guo; Sachse, Glen

    1990-01-01

    A high-sensitivity spectroscopic measurement of O2 using two-tone frequency modulation spectroscopy with a GaAlAs diode laser is presented. An oxygen sensor based on this technique would be non-intrusive, compact and possess high sensitivity and fast time response.

  16. Diode laser arrays for dynamic infrared scene projection

    NASA Astrophysics Data System (ADS)

    Beasley, D. Brett; Cooper, John B.

    1993-08-01

    A novel concept for dynamic IR scene projection using IR diode lasers has been developed. This technology offers significant cost and performance advantages over other currently available projector technologies. Performance advantages include high dynamic range, multiple wavebands, and high frame rates. A projector system which utilizes a 16-element linear array has been developed and integrated into the millimeter wave/infrared (MMW/IR) hardware-in-the-loop (HWIL) facility at the US Army Missile Command's (USAMICOM's) Research, Development, and Engineering Center (RDEC). This projector has demonstrated dynamic range in excess of 105, apparent temperatures greater than 2500 degree(s)C, and nanosecond response times. Performance characteristics for this projector system are presented in the paper. Designs for projectors to test other IR sensor configurations, including FPAs, have been developed and are presented as well. The FPA design consists of a linear array of diode lasers scanned by a polygon mirror. This low-cost projector offers high resolution, high contrast 2-D scenes at up to 10 KHz frame rates. Simulation of active IR countermeasures is another promising application of diode laser projector systems. The diode laser is capable of simulating flares or virtually any IR jammer waveform.

  17. A TUNABLE DIODE LASER STACK MONITOR FOR SULFURIC ACID VAPOR

    EPA Science Inventory

    A field prototype instrument for continuous in-situ monitoring of sulfuric acid vapor in industrial smoke stacks has been developed. The method of detection is dual wavelength differential absorption in the infrared. Two tunable diode lasers are locked to two specific frequencies...

  18. Fiber-optic interferometer using frequency-modulated laser diodes

    NASA Technical Reports Server (NTRS)

    Beheim, G.

    1986-01-01

    This paper describes an electrically passive fiber-optic interferometer which uses dual frequency-modulated laser diodes. Experimental results show that this type of interferometer can attain a displacement range of 100 micron with subnanometer resolution. This technique can serve as the basis for a number of high-precision fiber-optic sensors.

  19. 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.

  20. 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.

  1. LASERS: Low-threshold short-cavity diode laser for a miniature atomic clock

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D1 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.

  2. Laser radiation bracket debonding

    NASA Astrophysics Data System (ADS)

    Dostálová, Tat'jana; Jelínková, Helena; Šulc, Jan; Koranda, Petr; Nemec, Michal; Racek, Jaroslav; Miyagi, Mitsunobu

    2008-02-01

    Ceramic brackets are an aesthetic substitute for conventional stainless steel brackets in orthodontic patients. However, ceramic brackets are more brittle and have higher bond strengths, which can lead to bracket breakage and enamel damage during classical type of debonding. This study examined the possibility of laser radiation ceramic brackets removing as well as the possible damage of a surface structure of hard dental tissue after this procedure. Two types of lasers were used for the experiments - a laser diode LIMO HLU20F400 generating a wavelength of 808 nm with the maximum output power 20W at the end of the fiber (core diameter 400 μm, numerical aperture 0.22). As a second source, a diode-pumped Tm:YAP laser system generating a wavelength of 1.9 μm, with up to 3.8 W maximum output power was chosen. For the investigation, extracted incisors with ceramic brackets were used. In both cases, laser radiation was applied for 0.5 minute at a maximum power of 1 W. Temperature changes of the irradiated tissue was registered by camera Electrophysics PV320. After the interaction experiment, the photo-documentation was prepared by the stereomicroscope Nikon SMZ 2T, Japan. The surface tissue analysis was processed in "low vacuum" (30 Pa) regime without desiccation. This technique was used to record back-scattered electron images. Selecting the appropriate laser, resin, and bracket combination can minimize risks of enamel degradation and make debonding more safe.

  3. A High Power Amplifier for a Single Mode 1064 Laser

    NASA Astrophysics Data System (ADS)

    Stites, R. W.; O'Hara, K. M.

    2011-05-01

    We report on the construction of a high power amplifier system for a single mode 1064 nm laser. At the heart of this device is a 0.27% neodymium doped yttrium orthovanadate crystal that is double end pumped by two 30 Watt broadband diode arrays at 808 nm. For a 50 Watt TEM00 single freqency seed laser, we have observed an amplified power output in excess of 60 Watts for single pass configuration. A further increase in output power can be attained by retroreflecting the beam back through the crystal a second time. Such a device has direct application in the construction of optical lattices where high power single frequency lasers are required.

  4. High power Nd:YAG spinning disk laser.

    PubMed

    Ongstad, Andrew P; Guy, Matthew; Chavez, Joeseph R

    2016-01-11

    We report on a high power Nd:YAG spinning disk laser. The eight cm diameter disk generated 200 W CW output with 323 W of absorbed pump in a near diffraction-limited beam. The power conversion efficiency was 64%. The pulsed result, 5 ms pulses at 10 Hz PRF, was nearly identical to the CW result indicating good thermal management. Rotated at 1200-1800 RPM with He impingement cooling the disk temperature increased by only 17 °C reaching a maximum temperature of ~31 °C. The thermal dissipation per unit of output power was 0.61 watt of heat generated per watt of laser output, which is below the typical range of 0.8-1.1 for 808 nm diode pumped Nd:YAG lasers. PMID:26832242

  5. 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.

  6. 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.

  7. Compact laser diode drivers for military rangefinder applications

    NASA Astrophysics Data System (ADS)

    Giorgi, D.; Philippbar, J.

    2010-04-01

    Compact and high current laser diode drivers for pumping solid-state lasers have been developed and tested. Designed to operate from a single DL123 battery or equivalent, the OptiSwitch PLDD-150-1-1 delivers 150 A of peak current for 300 μs to a laser diode bar at a 1 Hz repetition rate. Measuring only 2.1 × 0.75 × 0.78 inches and weighing 15.2 g, the unit is suited for man-portable target designation, rangefinding, illumination, and remote sensing applications. This paper will discuss the design philosophy behind this class of drivers which offer peak currents up to 200 A plus lifetime testing of eight drivers all operating at elevated input voltage and temperature at 4.5 Hz for 10M shots without a single failure or degradation in performance. Lastly, temperature testing down to -40 degC will be discussed.

  8. Utilization of pulsed diode lasers to lidar remote sensing

    NASA Astrophysics Data System (ADS)

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

    2001-04-01

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

  9. 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.

  10. 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.

  11. 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.

  12. Quantity change in collagen following 830-nm diode laser welding

    NASA Astrophysics Data System (ADS)

    Tang, Jing; O'Callaghan, David; Rouy, Simone; Godlewski, Guilhem; Prudhomme, Michel

    1996-12-01

    The actual mechanism for production of laser welding of tissue is presently unknown, but collagen plays an important role is tissue welded after laser irradiance. The quantity change in collagen extracted from the abdominal aorta of Wistar rats after tissue welding using an 830 nm diode laser was investigated. The collagen contents following repeated pepsin digestion after acetic acid extraction were determined with Sircol collagen assay. Compared with untreated aorta, the collagen content of the treated vessel was obvious decreased immediately after laser irradiation and following an initial increase on day 3, there was a peak at day 10. The results suggest that a part of collagen molecules is denatured by the heat of laser. There is an effect of stimulating collagen synthesis after laser welding with parameters used in this study.

  13. Thermally tunable integrated planar Bragg-grating stabilized diode laser

    NASA Astrophysics Data System (ADS)

    Lynch, S. G.; Gates, J. C.; Berry, S. A.; Holmes, C.; Smith, P. G. R.

    2015-03-01

    A pair of external cavity diode lasers are fabricated using an integrated planar Bragg grating. The planar waveguide and Bragg reflector is UV-written within a glass-on-silicon chip. Intensity isolated, continuous wavelength tuning at > 1kHz modulation rate is acheived using micro-heating elements fabricated directly over the Bragg grating. Low RIN (<140dB) and low linewidth (δν ~ 200 kHz) operation is found using a heterodyne measurement. We demonstrate the lasers operating in phase-locked loop configuration where one laser is frequency-offset locked to the other.

  14. 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.

  15. 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.

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

    PubMed Central

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

    2015-01-01

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

  17. 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.

  18. Finite element analysis of laser-diode heat emission and design of PI fuzzy cooling system

    NASA Astrophysics Data System (ADS)

    Yu, Fusheng; Shen, Xiaoqin; Leng, Changlin; Li, Zhi

    2005-01-01

    In order to realize the coupling of the crystal spectrum line, the wavelength output by the laser-diode must be adjusted to be accordant with the peak value absorbed by laser crystal in the solid laser of the laser-diode pump. In this paper, the finite element analysis (FEA) of the heat emission of the to-3 encapsulated laser-diode was researched and an accurate PI+Fuzzy temperature control system was developed. The refrigeration and the accurate temperature control of the high-power laser-diode was realized by the semiconductor refrigerator. Combined with fussy control and PI control, a full solid refrigerator of the laser-diode was developed. AT89C51 MCU and CRI[1] fussy control arithmetic were used in this system. So the system has high temperature control precision and little chatting. The rate of change of the optical power peak value output by the laser-diode was less than 1%.

  19. Integration of mode-locked diode lasers

    NASA Astrophysics Data System (ADS)

    Coleman, A. Catrina; Hou, Lianping; Marsh, John H.

    2016-03-01

    Monolithic mode-locked semiconductor lasers are attractive sources of short optical pulses with advantages over more conventional sources in compactness, robustness, performance stability, power consumption, and cost savings. The use of quantum well intermixing (QWI) to integrate passive sections and surface etched distributed Bragg reflectors (DBR) into monolithic laser cavity will be described. The performance of the devices will be presented.

  20. 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

  1. 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. PMID:27307679

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

    DOEpatents

    Freitas, Barry L.; Skidmore, Jay A.

    2003-11-11

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

  3. 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.

  4. Diode laser ignition of explosive and pyrotechnic components

    SciTech Connect

    Jungst, R.G.; Salas, F.J.

    1990-01-01

    The Laser Diode Ignition (LDI) program at Sandia Laboratories has as its objective the development of optically ignited analogs to the presently used low energy, hot wire igniters, DDT detonators, and actuators. In our concept, optical energy would be transmitted from a diode laser to the explosive or pyrotechnic power via a fiber optic. The laser energy is coupled to the energetic powder through a hermetically sealed optical feedthrough in the charge cavity. Optical ignition has many advantages, most of which are related to the removal of electrical leads to the powder interface. This eliminates concerns such as sensitivity to electrostatic discharge and electromagnetic radiation, conductance after fire, and isolation resistance. The optical interface would also not have the corrosion tendency that has occasionally been a problem with bridgewires. Another convenient property of diode laser sources is that the current and voltage needed to drive them are quite similar to those now applied to bridgewires for hot wire ignition. Therefore LDI devices would have an overall electrical requirement which is nearly identical to that of the hot wire components they are replacing.

  5. 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

  6. 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.

  7. Progress in high-energy-class diode laser pump sources

    NASA Astrophysics Data System (ADS)

    Crump, P.; Frevert, C.; Bugge, F.; Knigge, S.; Erbert, G.; Tränkle, G.; Pietrzak, A.; Hüslewede, R.; Zorn, M.; Sebastian, J.; Lotz, J.; Fassbender, W.; Neukum, J.; Körner, J.; Hein, J.; Töpfer, T.

    2015-03-01

    A new generation of diode-pumped high-energy-class solid-state laser facilities is in development that generate multijoule pulse energies at around 10 Hz. Currently deployed quasi-continuous-wave (QCW) diode lasers deliver average inpulse pump powers of around 300 W per bar. Increased power-per-bar helps to reduce the system size, complexity and cost per Joule and the increased pump brilliance also enables more efficient operation of the solid state laser itself. It has been shown in recent studies, that optimized QCW diode laser bars centered at 940…980 nm can operate with an average in-pulse power of > 1000 W per bar, triple that of commercial sources. When operated at pulsed condition of 1 ms, 10 Hz, this corresponds to > 1 J/bar. We review here the status of these high-energy-class pump sources, showing how the highest powers are enabled by using long resonators (4…6 mm) for improved cooling and robustly passivated output facets for high reliability. Results are presented for prototype passively-cooled single bar assemblies and monolithic stacked QCW arrays. We confirm that 1 J/bar is sustained for fast-axis collimated stacks with a bar pitch of 1.7 mm, with narrow lateral far field angle (< 12° with 95% power) and spectral width (< 12 nm with 95% power). Such stacks are anticipated to enable Joule/bar pump densities to be used near-term in commercial high power diode laser systems. Finally, we briefly summarize the latest status of research into bars with higher efficiencies, including studies into operation at sub-zero temperatures (-70°C), which also enables higher powers and narrower far field and spectra.

  8. 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.

  9. Frequency noise characterisation of narrow linewidth diode lasers

    NASA Astrophysics Data System (ADS)

    Turner, L. D.; Weber, K. P.; Hawthorn, C. J.; Scholten, R. E.

    2002-01-01

    We examine several approaches to laser frequency noise measurement in the frequency and time domains. Commonly employed methods such as optical frequency discrimination and the Allan variance are found to be complex, expensive, time-consuming, or incomplete. We describe a practical method of demodulating a laser beat note to measure a frequency noise spectrum, using a phase-locked loop frequency discriminator based on a single low-cost integrated circuit. This method measures the frequency noise spectrum of a laser directly and in detail and is insensitive to intensity fluctuations. The advantages of this scheme are demonstrated through measurement of the frequency noise spectrum for two external cavity diode lasers (ECDL), clearly distinguishing several common noise sources. These are isolated and removed, reducing the individual laser rms linewidth from 2 MHz to 450 kHz. The spectrum is used to calculate the Allan variance, which shows almost none of the important information.

  10. Diode-Pumped Dye Laser Using a Tapered Optical Fiber

    NASA Astrophysics Data System (ADS)

    Patterson, Brian; Stofel, James; Myers, Elliot; Knize, Randy

    2015-05-01

    We describe the construction of a simple dye laser based on a single-mode optical fiber. Light from a 120-mW laser diode (λ = 520 nm) is launched into the fiber. The fiber is tapered to a diameter of approximately 1 μm and placed in Rhodamine 6G laser dye. The pump light interacts with the gain medium through the evanescent field outside the fiber causing stimulated emission, which couples back into the fiber. Mirrors on each end of the fiber provide the necessary feedback for lasing, and a grating is used to narrow the spectral output. We characterize the lasing threshold and output spectrum of the laser. This has been a good project for undergraduate students to learn about lasers and optics.

  11. Preliminary experiences on diode laser welding of skin

    NASA Astrophysics Data System (ADS)

    Reali, Umberto M.; Borgognoni, L.; Martini, L.; Chiarugi, C.; Gori, F.; Pini, Roberto; Toncelli, F.; Vanni, U.

    1994-12-01

    Dye enhanced laser welding has been recently proposed for skin closures to exploit the advantages of laser procedure (possible reduction of scar formation, no inflammatory reaction). In this preliminary study we used the diode laser-assisted technique to perform welding of rats' skin. In the pilot phase of the study we investigated the effect of the interaction between diode laser radiation and 20 full thickness skin wounds, performed on the shaved backs of 10 Wistar rats, using laser power in the range of 200 - 150 mW and, as the photoenhancing chromophore, Indocyanine Cardio-green (ICG) dye saturated solution in plasma. Ten wounds were sutured with 4.0 nylon thread, to provide a comparison with the traditional procedure. Wounds' samples were explanted on day 3 and 7 after the treatment, for histological evaluation. Clinical examination on the same days showed a high percentage of wounds dehiscence and presence of scales and crusts. Histologic examination demonstrated evidence of thermal injury and a heightened inflammation, superior to that of suture closures. In the second phase of the study, a lower laser power (150 - 80 mW), ICG-plasma-non saturated solution (ICG-sol) and ICG-plasma-saturated-sodium hyaluronate gel (ICG-gel), were used. Six wounds were filled with ICG-sol and six with ICG-gel, then irradiated at 150, 120 and 80 mW. Postoperative explants were performed on day 3 and 7. Clinical and histological results from this group were satisfactory: we recorded only one case of dehiscence, well healed wounds, no epidermal necrosis and a mild inflammatory reaction, reduced respect to that of traditional closure. We characterized the optimum range of parameters of diode laser-assisted technique to achieve an effective skin welding and the corresponding clinical and histologic pattern was described.

  12. Compact, efficient, scalable neodymium laser co-doped with activator ions and pumped by visible laser diodes

    NASA Astrophysics Data System (ADS)

    Scheps, Richard

    1994-02-01

    Efficient, low threshold laser emission from a laser crystal doped with chromium and neodymium ions is obtained when pumped by visible laser diodes in the range of 610 nm to 680 nm. A typical laser Cr,Nd:GSGG crystal having an extraordinarily broad absorption bandwidth allows high pump efficiencies when using visible laser diodes, particularly in comparison to the Nd:YAG laser. The broad absorption bandwidth tolerance of the Cr,Nd:GSGG crystal to the pumping wavelengths allows visible diode pumping of the neodymium transition without regard to the wavelength of the visible diodes. Longitudinal or end-pumping to take advantage of the emission properties of the visible laser diodes, a nearly hemispherical laser resonator configuration and other co-doped Cr,Nd laser host materials are disclosed.

  13. 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.

  14. Highly reliable contacts for lead-salt diode lasers

    NASA Astrophysics Data System (ADS)

    Lo, W.

    1981-02-01

    In order to improve the long term reliability of lead-salt diode lasers, ohmic contacts of multilayer, thin-film structures consisting of In plus Au, Pt, Ni, and Pd have been studied. Diode lasers of PbSnTe fabricated with a variety of contacts were tested during room-temperature storage and during accelerated aging tests. The results show that contact reliability can be improved when multiple overlapping films are used. After 4500 h of baking at 60 C, lasers with In-Au-Pd-Au contacts on both sides showed the least resistance increase (10%). For lasers with In-Au-Pt-Au contacts, 1 h of baking at 60 C is equivalent to 2 d storage at room temperature. Extrapolating these results, a 70% increase in contact resistance is expected for this type of laser after 9000 d of storage at room temperature. The data also suggests that a smaller increase in contact resistance can be expected for lasers fabricated with In-Au-Ni and In-Au-Pd-Au contacts.

  15. 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.

  16. 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.

  17. 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.

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

    PubMed Central

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

    2014-01-01

    Objective To compare the perioperative morbidity and early follow-up after diode laser vaporisation of the prostate (LVP) and its modification, diode laser under cold irrigation (LUCI) in patients with symptomatic benign prostatic hyperplasia, as the main disadvantages of LVP are the postoperative pain, dysuria and storage urinary symptoms. Patients and methods This was a single-centre prospective randomised control trial in which 100 patients were randomised to receive LVP (50) or LUCI (50) from June 2011 until July 2012. LUCI is similar to LVP except that it is done under normal irrigation with saline at 4 °C instead of saline at room temperature. The primary outcome measures were the International Prostate Symptom Score (IPSS), IPSS-Dysuria, a pain scale (PS), maximum flow rate (Qmax), a quality-of-life (QoL) score and the postvoid residual urine volume (PVR) after 1 month, then the IPSS, Qmax, QoL, and PVR at 3 and 12 months. Secondary outcomes included intraoperative surgical variables, e.g., the decline in core temperature, bleeding, peri- and postoperative morbidity. Results The baseline characteristics of both groups were similar. For the primary outcome measures, there was a statistically significant difference between the groups in all variables except Qmax after 1 month, in favour of LUCI. The mean (SD) IPSS at 1 month in the LVP group was 8.97 (1.68), statistically significantly different from that after LUCI, of 6.89 (1.5) (P < 0.05). The mean IPSS-Dysuria at 1 month was also significantly, at −2.32 (0.91) for LVP and 3.54 (1.07) for LUCI (P < 0.05). The respective mean PS at 1 month was 7.84 (2.92) and 5.7 (2.1) (P < 0.05). The QoL and PVR at 1 month were also significantly different. Within the first month 17% of patients in the LVP group and 4% in the LUCI group complained of transient urgency or stress incontinence, and this difference was statistically significant (P < 0.05). There was no significant bleeding in either group

  19. 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

  20. 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.

  1. Diode laser contact transscleral retinal photocoagulation: a clinical study.

    PubMed Central

    McHugh, D A; Schwartz, S; Dowler, J G; Ulbig, M; Blach, R K; Hamilton, P A

    1995-01-01

    AIM--To examine the clinical efficacy of contact transscleral retinal photocoagulation with a diode laser. METHODS--Transscleral retinal photocoagulation was performed on 36 eyes. The conditions treated included peripheral retinal breaks associated with retinal detachments (30 eyes) and giant retinal tears (six eyes). Of the 30 eyes with retinal detachments, 28 underwent transscleral photocoagulation to the site of drainage of subretinal fluid in an attempt to reduce the risk of hemorrhage. RESULTS--Threshold lesions were obtained with irradiances of between 95.4 W/cm2 and 191 W/cm2. Satisfactory chorioretinal adhesion was achieved in all eyes with retinal breaks and giant retinal tears. The only significant complications of treatment encountered were punctate choroidal haemorrhages (three eyes). Drainage related choroidal haemorrhage following earlier photocoagulation occurred in two of 28 eyes. CONCLUSIONS--This study confirms the clinical potential of transscleral diode laser photocoagulation in the therapy of surgical retinal conditions. Images PMID:8562540

  2. Airborne tunable diode laser measurements of trace atmospheric gases

    NASA Astrophysics Data System (ADS)

    Fried, Alan; Wert, Bryan P.; Henry, Bruce E.; Drummond, James R.

    1998-05-01

    Highly sensitive and accurate measurements of numerous trace gases are required to further our understanding of atmospheric processes. Tunable diode laser systems, which offer many advantages in this regard, can be designed for reliable field measurements on both ground-based and aircraft platforms. The present paper describes the long term effort at the National Center for Atmospheric Research (NCAR) to develop, employ, and validate a highly sensitive tunable diode laser absorption spectrometer for the measurement of various trace gases, including formaldehyde and carbon monoxide. This system was successfully employed on three recent aircraft campaigns. The present paper describes the aircraft instrument along with hardware and software features incorporated for high sensitivity, with particular emphasis on major modifications to the NCAR aircraft system over the past year.

  3. Laser-diode-based joint transform correlator for fingerprint identification

    NASA Astrophysics Data System (ADS)

    Lal, Amit K.; Zang, De Yu; Millerd, James E.

    1999-01-01

    A laser-diode-based joint transform correlator (JTC) is reported here for the identification and discrimination of fingerprints. The system employs compact and inexpensive laser diodes as the light sources and a bacteriorhodopsin (BR) film in the Fourier plane, which can record the joint power spectrum without the need for expensive spatial light modulators or CCD cameras. The BR film also introduces nonlinearities in the Fourier plane which can improve JTC performance. In addition, real-time, all-optical programmable spatial filtering is demonstrated to improve the discrimination of the system. We present computer modeling and experimental results of this optical correlator, which shows excellent potential for the identification and discrimination of fingerprints.

  4. Diode laser for excisional biopsy of peripheral ossifying fibroma

    PubMed Central

    Chawla, Kirti; Lamba, Arundeep Kaur; Faraz, Farrukh; Tandon, Shruti; Ahad, Abdul

    2014-01-01

    Peripheral Ossifying Fibroma is one of the commonest occurring reactive lesions on gingiva. It is associated with local irritational factors and often interferes with speech, mastication and maintenance of oral hygiene, in addition to being aesthetically unpleasant. It is usually treated with surgical excision using scalpel and removal of irritational factors, often resulting in mucogingival defect. Other modalities such as radiosurgery and electrocautery have also been used for its management, but they cause changes in microarchitecture of biopsy specimen, altering the histologic picture for true diagnosis. We are presenting a case of excisional biopsy of this lesion in an adult female using a diode laser with excellent post-operative results, without affecting microarchitecture of biopsy specimen. The patient is being followed for last 1 year and no sign of recurrence has been found. A diode laser may offer a good alternative modality for management of such cases. PMID:25225570

  5. 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.

  6. Measuring Young's modulus using a self-mixing laser diode

    NASA Astrophysics Data System (ADS)

    Lin, Ke; Yu, Yanguang; Xi, Jiangtao; Fan, Yuanlong; Li, Huijun

    2014-03-01

    This paper presents a novel approach for determining the Young's modulus by using a self-mixing laser diode (SMLD). An SMLD system consists of a laser diode (LD), a microlens and an external target. With a small portion of light backscatterd or reflected by the target re-entering the LD inside cavity, both the amplitude and frequency of the LD power are modulated. This modulated LD power is referred as a self-mixing signal (SMS) which is detected by the photodiode (PD) packaged in the rear of the LD. The external target is the tested sample which is in damping vibration excited by a singular elastic strike with an impulse tool. The vibration information from the tested sample is carried in the SMS. Advanced data processing in frequency-domain is applied on the SMS, from which the resonant frequency of the vibration can be retrieved, and hence Young's modulus is calculated. The proposed method has been verified by simulations.

  7. 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.

  8. 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.

  9. 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.

  10. ND laser with co-doped ion(s) pumped by visible laser diodes

    NASA Astrophysics Data System (ADS)

    Scheps, Richard

    1993-04-01

    The 1.06 microns Nd transition in a co-doped Cr,Nd:Gd3Sc2Ga3O12 (Cr,Nd:GSGG) gain element is obtained by diode pumping Cr(3+) at 670 run and produces efficient, low threshold laser operation. Although co-doped Cr,Nd:GSGG was developed for more efficient flashlamp pumping, it has the desirable property of having an extraordinarily broad absorption to allow for efficient diode pumping relative to the ND:YAG laser. The consequent broad bandwidth tolerance of the Cr,Nd:GSGG for the diode pumping radiation allows diode pumping of the 1.06 microns transition without regard to the wavelength of the visible diodes which has the potential for reducing the cost of the semiconductor pump and also demonstrates the extended versatility of these diodes which previously had been restricted to pump the Cr(3+) tunable vibronic lasers. CW and long pulse diode pumping provided pump power levels as high as 300 mW CW and 1 W pulsed. The lowest threshold power was measured at 938 micron W and the highest output power was obtained at 43 mW CW and 173 mW pulsed. The best slope efficiency obtained was 42.1%, 78% of the theoretical maximum. Loss measurements indicate a value of 0.4%/cm.

  11. 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.

  12. 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.

  13. Diode-pumped Nd:YAG laser for precision laser machining

    SciTech Connect

    Machan, J.; Valley, M.; Holleman, G.; Mitchell, M.; Burchman, D.; Zamel, J.; Harpole, G.; Injeyan, H.; Marabella, L.

    1996-10-01

    Results are presented on a high power, diode-pumped, pulsed Nd:YAG laser for precision laser machining. The laser is an unstable resonator with a graded reflectivity outcouplers, generating a beam with excellent beam quality. The gain medium is a single zig-zag slab, pumped symmetrically by diode arrays. The use of diode arrays minimizes the thermal loading on the slab, and the zig-zag path averages thermal distortions in the zig-zag dimension. Measurements of beam divergence as a function of diode duty-cycle will be presented. Available pulse formats will also be discussed. To date, the laser has produced 720 W at 20% diode duty-cycle with a stable cavity and 550 W at 20% duty cycle with an unstable cavity in close agreement with model predictions. The beam divergence has been measured to be 1.7 times diffraction-limited at 20% duty cycle. The laser has been operated with pulse lengths from 20 {micro}s to 1 ms and is being used to obtain laser processing data, with some results shown.

  14. 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.

  15. Passively cooled diode laser for high-power applications

    NASA Astrophysics Data System (ADS)

    Bonati, Guido F.; Hennig, Petra; Schmidt, Karsten

    2004-06-01

    For the usage of diode lasers in industrial applications, customers ask today for expected lifetimes of more then 30.000 hours. To match the request for low costs per Watt as well, the output power has to be as high as possible. To achieve a maximum power out of a diode laser bar, heat removal must be extremely efficient. Today, micro channel heatsinks (MCHS) are the only way to achieve the high power level of 50W. But due to erosion/corrosion effects the lifetime of MCHS is limited at 15000...20.000 hours today. Finally we have to determine that for selected semiconductor materials not the semiconductor but the heatsink is limiting the expected lifetime of high power diode lasers today. Passive heat sinks based on solid copper are not limiting lifetime expectations in any way. But as cooling efficiency is lower, the power has to be reduced to a level of 30...40W. The first time ever, the JENOPTIK Laserdiode can present today a cooling technique that combines the passive cooling of a diode laser bar with the optical output a power of a bar, mounted on a MCHS. Using a special heat exchanger called DCB (patent pending) we were able to increase the power to 50W per bar while looking forward to extend the expected lifetime to more than 30.000 hours for selected materials. Restrictions on the quality of the water by means of deionization grade or PH- level are no longer necessary. The device is operating with regular water. The flow rate is as low as on MCHS, the pressure drop over the DCB is comparable. Additionally, the measurements will show an even lower thermal resistance compared to MCHS. The second generationof engineering samples is built up for pumping rows. A vertical stack design will be available for evaluating purposes soon. All these efforts are part of the JENOPTIK Laserdiode's LongLifeTechnology.

  16. Computer holography by means of the laser diodes

    NASA Astrophysics Data System (ADS)

    Borodin, Arthur N.; Ilchenko, Volodymyr; Malov, Alexander N.; Sychevskiy, Alexey V.

    2007-02-01

    A computer holography is the optical hologram recording on the CCD-matrix with digital reconstruction of the 2Dimages for the different volume object cross-sections. The possibility to use compact semiconductor laser diodes in the computer holography for 3D-scene registration is experimentally proved in the D. Gabor's scheme. For off axis hologram recording the S. Benton's scheme for holography using is suggested.

  17. 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.

  18. DFB laser diode operation at 77 K

    NASA Astrophysics Data System (ADS)

    Hopkinson, D. A.; Cornish, S. L.; Edwards, N. H.; Baird, P. E. G.; Cockburn, A.; Cameron, K.

    1996-05-01

    The low-temperature operation of distributed feedback semiconductor lasers in the vicinity of 0957-0233/7/5/011/img9 is investigated. The room temperature properties of a sample DFB laser are given and its power and frequency characteristics at 77 K are compared. In this way, the linearity of the temperature against frequency relation down to liquid nitrogen temperature is confirmed and a reduction in the threshold current to near zero is also shown. For spectroscopic purposes, it was found that stabilization of the laser temperature at 77 K is possible to within 50 mK over a range of about 77 - 87 K. This corresponds to a frequency change of about 120 GHz. The Schawlow - Townes relation predicts a reduction in linewidth with temperature; some evidence for this is given.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Fast mode-hop-free acousto-optically tuned laser with a simple laser diode.

    PubMed

    Bösel, André; Salewski, Klaus-Dieter; Kinder, Thomas

    2007-07-01

    A mode-hop-free tunable external-cavity Littrow diode laser with intracavity acousto-optic modulators (AOMs) has been built. The modes of the red laser diode without a special antireflection coating are shifted by varying the injection current. The external resonator modes and the grating selectivity are independently electrically alterable by two AOMs. Thus, a tuning of the external resonator over up to 1900 GHz is possible. A precise computer control of laser diode and AOMs allowed a single-mode tuning of the whole laser with a tuning range of 225 GHz in 250 s. Additionally, we demonstrated fast tuning over 90 GHz in 190 micros and a repetition rate of 2.5 kHz. PMID:17603626

  5. 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.

  6. 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.

  7. External cavity diode laser with very-low frequency drift

    NASA Astrophysics Data System (ADS)

    Takamizawa, Akifumi; Yanagimachi, Shinya; Ikegami, Takeshi

    2016-03-01

    An external cavity diode laser with significant mechanical robustness was installed in a housing that was sealed from outside for eliminating variations in the refractive index of air. Using the feedback signal for a frequency lock, it was found that the variation in the laser frequency under free running was suppressed to 275 MHz over one month and depended on the room temperature. Moreover, the upper limit of the linear frequency drift rate was evaluated as intrinsically 40 Hz/s. The frequency lock is expected to be sustainable for more than 110 days with temperature-controlled housing.

  8. Monolithically integrated twin ring diode lasers for rotation sensing applications

    NASA Astrophysics Data System (ADS)

    Osiński, Marek; Cao, Hongjun; Liu, Chiyu; Eliseev, Petr G.

    2006-02-01

    Design, fabrication, and characterization of monolithically integrated ring diode lasers (RDLs) with relatively large size are reported. Fully functional optoelectronic integrated circuits containing integrated unidirectional RDLs, photodetectors, and coupling waveguides are demonstrated. Multiple switching of lasing direction is observed in RDL with quantum-well active regions, and an S-section or spiral absorbers are used to suppress directional switching and to obtain a more stable unidirectional operation. Unidirectionality of the RDL operation is greatly improved in lasers with quantum-dot active regions.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. The reliability of /AlGa/As CW laser diodes

    NASA Astrophysics Data System (ADS)

    Ettenberg, M.; Kressel, H.

    1980-02-01

    Major factors bearing on the reliability of (AlGa)As CW laser diodes are reviewed with attention given to the degradation modes of facet mirror damage, contact degradation, and internal damage. Detailed results are provided for the oxide-defined stripe-contact double-heterojunction lasers operated for more than 40,000 h with extrapolations indicating a median time to failure between 100,000 and 1,000,000. Facet damage and contact degradation appear to be under control, and internal damage remains the dominant failure mechanism. Most of the data deals with threshold current increase; however, shifts in far-field pattern and changes in laser modulation characteristics, including self-sustained oscillations, may affect laser performance in real systems.

  15. 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.

  16. 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.

  17. Diode-laser-pumped Nd:YAG laser injection seeding system

    SciTech Connect

    Schmitt, R.L.; Rahn, L.A.

    1986-03-01

    We have designed and tested a compact injection seeding system consisting of a diode-laser-pumped Nd:YAG master oscillator and a permanent-magnet Faraday isolator. With active resonator frequency stabilization, this system permits highly reliable single-axial-mode operation of a Q-switched Nd:YAG laser over a period of hours. The system is capable of injection seeding both stable and unstable resonator designs and is suitable for injection seeding commercial lasers with only minor modifications.

  18. 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.

  19. 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.

  20. Simple mathematical model for designing laser diode focusing optics with a large numerical aperture

    NASA Astrophysics Data System (ADS)

    Sun, Haiyin

    2014-10-01

    A simple mathematical model is derived for conveniently designing laser diode focusing optics with a large numerical aperture. The astigmatism of laser diode beams and the lens truncation effects are considered in the model. The linearly polarized nature of laser diode beams is also included. Two design examples using this model are presented. Design results show that the lens truncation will increase the size of the focused spot and the value of the M2 factor, and the lens truncation caused a focal shift, which is not enough to correct laser diode beam astigmatism.

  1. 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.

  2. 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.

  3. 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.

  4. Viability and Regeneration of Chondrocytes after Laser Cartilage Reshaping Using 1,460 nm Diode Laser

    PubMed Central

    Mo, Ji-Hun; Kim, Ji-Sun; Lee, Jae-Wook; Chung, Phil-Sang

    2013-01-01

    Objectives Cartilage reshaping by laser irradiation is used to correct septal and auricular cartilage deformities. Chondrocyte viability following laser irradiation and reshaping has been well established. However, the regeneration process of chondrocyte after laser irradiation has not been revealed yet. The aims of this study were to determine the mechanism of cartilaginous thermal injury and the regenerative process of damaged cartilage following laser irradiation. Methods Laser irradiation was performed on human septal cartilage and rabbit auricular cartilage using a 1,460-nm diode laser. We observed change in the shape of cartilage and evaluated the extent of cartilage injury using live/dead cell assay via confocal microscopy. Hoechst and propidium iodide (PI) staining was used to evaluate the mechanism of chondrocyte injury after laser irradiation. To evaluate the regeneration of cartilage, laser irradiated cartilages were reimplanted into a subperichondrial pocket and were harvested at 1, 2, and 4 weeks after reimplantation for viability assessment and histologic examination. Results Laser irradiation using a 1,460-nm diode laser produced a marked shape change in both human septal and rabbit auricular cartilages. Thermal damage on cartilage was correlated with the exposure time and the laser power. Hoechst and PI staining showed that chondrocyte death by laser irradiation was due to mainly necrosis, rather than apoptosis. In lower power treatment group (0.3 W and 0.5 W), all the chondrocytes regenerated within 4 weeks, however, in 1 W treatment group, chondrocytes could not regenerate until 4 weeks. Conclusion Reshaping of cartilage using 1,460 nm diode laser was attained concurrently with the thermal injury to the chondrocytes. The extent of thermal damage on chondrocytes was dependent on the exposure time and the laser power and the damaged chondrocytes irradiated with lower level of laser power could be regenerated after reimplantation into

  5. 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.

  6. 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.

  7. 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.

  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. 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

  10. 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.

  11. 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

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

    NASA Technical Reports Server (NTRS)

    Newman, Bronjelyn; Halpern, Joshua B.

    1997-01-01

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

  13. Efficient femtosecond Yb:YAG laser pumped by a single-mode laser diode

    NASA Astrophysics Data System (ADS)

    Agnesi, Antonio; Greborio, Alessandro; Pirzio, Federico; Reali, Giancarlo

    2011-08-01

    Single-mode diodes enable a particularly simple, compact and effective pumping of solid-state laser devices for many specialized applications. We investigated a single-mode, 300-mW laser diode for pumping at 935 nm a Yb:YAG laser passively mode-locked by a semiconductor saturable absorber. Relatively short pulse generation (156 fs), tunable across 1033-1059 nm has been demonstrated. An optical-to-optical efficiency of about 28% has been obtained with 320 fs long pulses. Therefore, contrarily to what previously believed, compact diode-pumped ultrafast Yb:YAG oscillators can reliably and efficiently deliver pulses in the range of ≈ 100-200 fs with few tens of mW, which are very appealing for bio-diagnostics and amplifier seeding applications.

  14. Developments in laser joining and welding of plastics using high-power laser diodes

    NASA Astrophysics Data System (ADS)

    Hoult, Tony; Ong, Raymond

    2002-02-01

    Diode lasers are now being employed in industry for a range of applications, in particular they are starting to be used as alternatives to conventional techniques for thermal joining of plastics. This is being assisted by the use of improved reliability aluminum-free diodes and diode laser systems, partly due to a better understanding of failure mechanisms. The laser welding and related techniques are dependent on transmission of part of an infra-red beam through the upper layer of a joint and semi-quantitative assessment of this is required for specific applications. The technique is applicable not only to high average powers, but also to very low average power, in this regime delicate thin-walled components may be joined. Recent developments using derivatives of this technique have shown that a wide range of similar and dissimilar material combinations may be joined.

  15. A passively mode-locked intracavity frequency doubled Nd:YVO4 femtosecond green laser based on graphene

    NASA Astrophysics Data System (ADS)

    Shi, R. P.; Bai, Y.; Qi, M.; Chen, X. M.; Wei, H. D.; Ren, Z. Y.; Bai, J. T.

    2014-02-01

    By using an atmospheric-pressure chemical vapor deposition (APCVD) method with a C2H2 carbon source, seven-layer graphene films as saturable absorbers are fabricated and transferred to an anti-reflective mirror of 1064 nm wavelength range. Based on this transmission-type graphene saturable absorber mirror (GSAM), a continuous wave (CW) passively mode-locked femtosecond green laser is achieved by 808 nm laser diode (LD) end-pumped Nd:YVO4 crystal and type-I critical phase-matched LBO crystal intracavity frequency doubling for the first time. Stable ultrashort green laser pulses as short as 374 fs are measured with a repetition rate of 71.4 MHz and an average output power of 117 mW at a central wavelength of 531.7 nm.

  16. 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.

  17. Microarterial anastomoses using the diode laser: long term morphological results

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Prudhomme, Michel; Rouy, Simone; Godlewski, Guilhem; Ovtchinikoff, Serge; Delacretaz, Guy P.; Salathe, Rene-Paul

    1996-01-01

    In a series of 70 Wistar rats submitted to a noncontact diode laser-assisted carotid end-to-end anastomosis (LAMA) versus controlateral manual suture microanastomosis (CMA), contrast angiography and scanning electron microscopy were performed in a group of 18 animals at a long-term follow up to 7 months after operation. The investigation of angiography realized by means of a CGR General Electric DG 200 with a 512 digital matrix gave precise images of vessel wall repair and vessel patency. It permitted a simultaneous comparison between laser and manual anastomosis. Patency rate was 83% in LAMA and 78% in CMA. Nonlethal complications such as 1 stenosis, 2 thromboses in LAMA and 1 stenosis, 2 thromboses, and 1 pseudoaneurysm in CMA were observed. The results could be correlated to scanning electron microscopy findings and confirmed the morphological superiority of the laser technique.

  18. 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.

  19. Reliable Optical Pump Architecture for Highly Coherent Lasers Used in Space Metrology Applications

    NASA Technical Reports Server (NTRS)

    Erlig, Herman; Qiu, Yueming; Poberezhskiy, Ilya Y.; Meras, Patrick L.; Chang, Daniel H.; Wu, Yen-Hung

    2012-01-01

    The design and initial demonstration of a laser pump module (LPM) incorporating single-mode, grating-stabilized 808-nm diode lasers and a low-loss, high-port-count optical combiner are completed. The purpose of the developed LPM is to reliably pump an Nd:YAG crystal in the laser head (LH), which serves as the optical metrology source for SIMLite mission. Using the narrow-linewidth, single-mode laser diodes enables placement of the pump power near Nd adsorption peak, which enhances pumping efficiency. Grating stabilization allows for stable pump spectra as diode operating temperature and bias current change. The low-loss, high-port-count optical combiner enables efficient combining of tens of pumps. Overall, the module supports 5+ years of continuous operation at 2 W of pump power with reliability approaching 100 percent. The LPM consists of a laser diode farm (LDF) and a pump beam combiner (PBC). An array of 807- to 808-nm fiber-pigtailed laser diodes makes up the LDF. A Bragg grating in each 5- m core single-mode (SM) fiber pigtail acts to stabilize the lasing spectra over a range of diode operating conditions. These commercially available single-mode laser diodes can deliver up to 150 mW of optical power. The outputs from the multiple pumps in the LDF are routed to the PBC, which is a 37-input by 1-output all-fiber device. The input ports consist of 5- m core SM fiber, while the output port consists of 105- m core, 0.15 NA (numerical aperture) multi-mode (MM) fiber. The combiner is fabricated by fusing the 37 input fibers while simultaneously tapering the fused region. At the completion of this process, the MM fiber is spliced to the end of the adiabatic taper, and, for protection, the combiner is sheathed by a capillary tube. A compact and robust metal housing was designed and fabricated to protect the PBC during space deployment.

  20. 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

  1. Preliminary Study on Generating Condition of Laser Sustained Plasma using 1 kW CW Diode Laser

    NASA Astrophysics Data System (ADS)

    Nishimoto, Koji; Kumita, Mamoru; Matsui, Makoto

    2015-09-01

    In the laser sustained plasma of conventional laser driven plasma wind tunnel, CO2 laser have been used. However, the efficiency of is about 10%. Recently, the development of diode laser is remarkable and the energy efficiency of it reaches nearly 80% in laboratory stage. Therefore, in our research group, the generation of laser sustained plasma using diode laser is being tried. In this study, the generation threshold of it was numerically calculated. Assuming that focused laser diameter is 200 um, in the condition of the pressure of 0.1-1 MPa, it was deduced that the threshold of laser power is about 500 W.

  2. 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.

  3. 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.

  4. 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

  5. Performance of commercial laser diodes in fluorimetric detection

    NASA Astrophysics Data System (ADS)

    Wersig, C.; Finke, W.; Handler, E.; Josel, Hans-Peter; Schmidt, Elmar

    1993-05-01

    We have developed a compact and sensitive detection system based on the fluorescence excitation by commercial laser diodes in the VIS and NIR. The system comprises separate excitation, sample, and detection chambers and shows the potential of quantitatively determining immunological and other parameters with small and rugged instruments. Our examinations specifically addressed technical aspects of laser diodes which are responsible for the quality of fluorescence excitation, such as the characterization of the mode structure, the temperature and current dependency of the optical power emission, and the selection and adjustment of the laser wavelengths for optimal overlap with the fluorophors' absorption maxima (namely rhodamine 800, indocyanine green IR-125, and latex-bound dyes). Signal-to- noise level ratios of about 1:1 are reached at sub-nanomolar concentrations in an illuminated sample of 20 (mu) l using a standard photomultiplier tube in analog mode as the detector. Different arrangements of optical filters (e.g., interference, colored-glass type, and polarizing filters) have been optimized with regard to the excitation and detection paths. Furthermore, measures toward an internal calibration of the system have been investigated.

  6. High-power diode lasers in spray process diagnostics

    NASA Astrophysics Data System (ADS)

    Larjo, Jussi

    2005-03-01

    Spray processes are commonly employed in many kinds of surface treatment applications, most prominently in medical, material processing and manufacturing industries. While spraying is a well established technology, we still lack complete understanding of all interactions within a given spray process. This is because the physical models of many subprocesses, like turbulent gas flow, particle formation and gas-particle interaction, are limited and often provide only qualitative predictions on the real process. Imaging measurements are essential in gaining better understanding of a spray process. They offer a way to measure properties of both the complete spray plume and individual droplets. A spray analysis system typically requires a high-power stroboscopic light source; Xe flashlamps and Q-switched solid state lasers have been the most common choice until recently. The development of high-power diode lasers has provided a versatile, low-cost and easy to use light source for the analysis of spray processes. We present a real-time diode laser based imaging system to measure droplet density, size and velocity distributions in a spray, together with the spray plume geometry.

  7. Comprehensive Welding of Thermoplastics by a Diode Laser

    NASA Astrophysics Data System (ADS)

    Sato, Kimitoshi; Saito, Takushi; Kurosaki, Yasuo

    This paper deals with a development of “comprehensive" laser welding of thermoplastics with versatility in color and shape of products. Overlap welding of thermoplastics is one of the features of application of diode lasers. Most of thermoplastics are transparent to diode lasers; therefore it is need to weld plastic article with colorant. The influence of absorptance and transmittance of overlapping colored plastics were studied. Various colored plastics with infrared-transparent pigments were tested as the welding material. The appropriate absorptance and transmittance of overlapping colored plastic were examined. The feasibility of the technique of welding of transparent plastics using infrared-absorbing layer was also investigated. The temperature distribution within the plastics was calculated by numerical simulation in order to estimate the validity of the proposing experimental systems. It was confirmed by the experiments that the 35μm film, which shows only 10% in absorptance is enough to weld a pair of transparent articles as infrared-absorbing layer.

  8. Diode-laser-based ultraviolet absorption sensor for nitric oxide

    NASA Astrophysics Data System (ADS)

    Hanna, S. F.; Barron-Jimenez, R.; Anderson, T. N.; Lucht, R. P.; Caton, J. A.; Walther, T.

    2002-07-01

    An all-solid-state continuous-wave laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule has been developed and demonstrated. The single-mode, tunable output of a 10-mW, 395-nm external-cavity diode laser (ECDL) is sum-frequency-mixed with the output of a 115-mW, frequency-doubled, diode-pumped Nd:YAG laser in a beta-barium-borate crystal to produce 40 nW of tunable radiation at 226.8 nm. The wavelength of the 395-nm ECDL is then scanned over NO absorption lines to produce fully resolved absorption spectra. Initial results from mixtures of NO in nitrogen in a room-temperature gas cell are discussed. The estimated NO detection limit of the system for a demonstrated absorption sensitivity of 2×10-3 is 0.2 ppm per meter of path length for 300 K gas. The estimated accuracy of the measurements is ±10%.

  9. Temperature control during diode laser welding in a human cornea

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Matteini, Paolo; Pini, Roberto; Menabuoni, Luca

    2007-07-01

    Diode laser welding is a technique proposed in ophthalmic surgery to induce immediate sealing of clear corneal wounds. The welding effect is achieved irradiating the area, previously treated with a chromophore, by the use of a low power diode laser: the resulting thermal effect induces structural modifications in the stromal collagen, that welds upon cooling. We present a study on the temperature dynamics developing during welding in a human eye. An infrared thermocamera was used to measure the temperature variations on the surface of the cornea during clinical penetrating keratoplasty (corneal transplant). The experimental data were used as a starting point for a theoretical investigation of the temperature rising inside the ocular structures: we developed a mathematical model based on the bio-heat equation and solved by the use of the Finite Element Method (FEM). The predictive accuracy was verified by comparing the temperature post-processing description with the results obtained from the thermographic data. The model was then used to study the temperature rise and heat propagation inside the eye. Experimental results and model analysis indicated the occurrence of heat confinement during the treatment procedure and a modest enhancement of the temperature (reaching about 55°C inside the laser treated wound), thus evidencing the safety of the procedure in clinical applications.

  10. 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.

  11. Precision dispensing of small volumes of albumin solder for laser-assisted wound closure

    NASA Astrophysics Data System (ADS)

    Sorg, Brian S.; McNally-Heintzelman, Karen M.; Chan, Eric K.; Frederickson, Christopher J.; Welch, Ashley J.

    1999-06-01

    Recent laser-tissue soldering work in our lab has demonstrated the feasibility of building a solder bond from individually coagulated small droplets using a precision pipette for the deposition of the solder droplets. This method of using small, precise volumes of solder to build a bond may result in stronger and more reproducible bonds than coagulating an equivalent large volume of solder all at once. We have investigated the technique further in this study. The solder was dispensed onto the intimal side of a bovine aorta substrate and irradiated with an 808nm diode laser. A bond was created across an incision in the tissue substrate by alternately dispensing and coagulating each small volume of solder, or by coagulating a single large equivalent volume. Acute strength analysis was performed on the solder bond. Future work will concentrate on testing a bench-top solder dispensing device and investigating the feasibility of turning the deice into a prototype tool for clinical applications.

  12. Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

    NASA Technical Reports Server (NTRS)

    Williams, A.; Seidel, D. J.; Maleki, J.

    1993-01-01

    A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.

  13. Diode laser excited optogalvanic spectroscopy of glow discharges

    SciTech Connect

    Barshick, C.M.; Shaw, R.W.; Post-Zwicker, A., Young, J.P.; Ramsey, J.M.

    1996-10-01

    The development of diode-laser-excited isotopically-selective optogalvanic spectroscopy (OGS) of uranium metal, oxide and fluoride in a glow discharge (GD) is presented. The technique is useful for determining isotopic ratios of {sup 235}U/({sup 235}U + {sup 238}U) in the above samples. The precision and accuracy of this determination is evaluated, and a study of experimental parameters pertaining to optimization of he measurement is discussed. Application of the GD-OGS to other f-transition elements is also described.

  14. Record-brightness laser-diode bars for fiber coupling

    NASA Astrophysics Data System (ADS)

    Dogan, M.; Pathak, R.; Ellison, S.; Eppich, H.; Campbell, G.; Vignati, J.; Jacob, J. H.; Lang, K. D.; Chin, R. H.; Knapczyk, M. T.; Sun, W.; Fulghum, S. F.; Chin, A. K.

    2012-03-01

    High brightness, laser-diode bars are required for efficient coupling into small-core optical-fibers. Record power and brightness results were achieved using 20% fill-factor, 980nm, 1cm-wide, 4mm cavity-length bars. Lifetimes of single bars, operated CW at 200W and 20°C, exceed 1000hr. Due to superb thermal management, the power conversion efficiency (PCE) exceeds 60% at 200W output power. Similar lifetime and PCE were obtained for a 3-bar stack emitting 600W output power.

  15. 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.

  16. Stable isotope analysis using tunable diode laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Becker, Joseph F.; Sauke, Todd B.; Loewenstein, Max

    1992-01-01

    Ratios of C-12/C-13 in CO2 have been measured using a tunable diode laser (TDL) spectrometer to an accuracy of better than 0.4 percent. These results were made possible by the use of state-of-the-art high-temperature TDLs, an etalon and wavenumber calibration technique, high-speed assembly language controlled data acquisition, and the ratioing of absorbances from simultaneously acquired sample and reference data scans. The dual beam spectrometer that is employed uses the sweep integration technique in a spectral region where adjacent spectral lines are of approximately equal absorbance at the expected isotopic abundances.

  17. 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.

  18. 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.

  19. 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.

  20. A non-critically phase matched KTA optical parametric oscillator intracavity pumped by an actively Q-switched Nd:GYSGG laser with dual signal wavelengths

    NASA Astrophysics Data System (ADS)

    Zhong, Kai; Guo, Shibei; Wang, Maorong; Mei, Jialin; Xu, Degang; Yao, Jianquan

    2015-06-01

    A non-critically phase matched eye-safe KTA optical parametric oscillator intracavity pumped by a dual-wavelength acousto-optically Q-switched Nd:GYSGG laser is demonstrated. Simultaneous dual signal wavelength at 1525.1 nm/1531.2 nm can be realized using only one laser crystal and one nonlinear crystal. When the absorbed diode pump power at 808 nm is 7.48 W, the maximum output power, single pulse energy and peak power are 296 mW, 2.96 μJ and 6.4 kW, respectively. As the signal wavelengths exactly locates at the absorption band of C2H2, such an Nd:GYSGG/KTA eye-safe laser has good application prospects in differential absorption lidar (DIAL) for C2H2 detection and difference frequency generation for terahertz waves at 0.77 THz.

  1. Laser diode pumped 1μ Nd;YAG and Nd:BEL lasers

    NASA Astrophysics Data System (ADS)

    Scheps, R.; Poirier, P.; Myers, J. F.; Heller, D. F.

    1989-10-01

    Peformance data for laser diode-pumped cw Nd:YAG and Nd:BEL lasers are presented. Two single stripe laser diodes are used as the pump source, each emitting 1 W in the pump band. The heat sink for the lasers is temperature controlled to allow for wavelength tunability. The resonator is based on a hemispherical design. Output and pump threshold measurements were made and gain and loss for Nd in both hosts were measured. The output power from the Nd:YAG rod was in excess of 870 mW with a slope efficiency of 58% and an overall electrical efficiency of 13%. In Nd:BEL, the output power was in excess of 635 mW with a slope efficiency of 49% and an electrical efficiency of 9.5%.

  2. Tunable diode laser development and spectroscopy applications; Proceedings of the Meeting, San Diego, CA, August 25, 26, 1983

    NASA Astrophysics Data System (ADS)

    Lo, W.

    1983-01-01

    Aspects of tunable diode laser development are discussed, taking into account tunable diode lasers for 3-30 micron infrared operation, Cd-diffused lead salt diode lasers and their application in multicomponent gas analysis systems, heterojunction stripe geometry lead salt diode lasers grown by molecular beam epitaxy, Pb(1-x)Sn(x)Te lasers with high efficiencies, lasing characteristics of PbSnSeTe-PbSeTe lattice-matched double heterostructure laser diodes, and the development of ion-implantation confined shallow mesa stripe (Pb,Sn)Te/Pb(Te/Se) DH laser diodes. Other topics considered are related to industrial applications, applications for tunable diode laser instrumentation, and molecular spectroscopy applications. Attention is given to tunable diode laser applications to cigarette smoke analysis, automated tunable diode laser monitoring systems, a review of progress in remote sensing by tunable diode laser heterodyne spectroscopy, tunable diode laser optogalvanic spectroscopy of molecules, tunable diode laser spectroscopy of molecules in solids and on surfaces, and measurements of CO in engine exhaust.

  3. 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%.

  4. 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. ...

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

    NASA Astrophysics Data System (ADS)

    Jambunathan, V.; Miura, T.; Těsnohlídková, L.; Lucianetti, A.; Mocek, T.

    2015-01-01

    Laser performance of Yb:YAG at different cryogenic temperatures pumped by a fiber coupled diode laser emitting at 940 and 969 nm were presented. The pump laser diode bandwidth, absorption bandwidth as well as absorption of the laser material at cryogenic temperatures play a vital role on laser performance. The laser threshold decreases and the output power and slope efficiency increase when cooled to cryogenic temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

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

  7. 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.

  8. 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.

  9. 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.

  10. Near-infrared laser diodes in monitoring applications

    NASA Astrophysics Data System (ADS)

    Patonay, Gabor; Zen, Jyh-Myng; Czuppon, Tibor

    1992-05-01

    Absorption and fluorescence spectroscopy has proven to be a valuable analytical tool for environmental and process monitoring. Several publications have addressed different spectroscopic applications related to process monitoring. Since most chemicals absorb in the UVIVis part of the spectrum, the majority of laser applications utilize this shorter wavelength region. Nevertheless, the utilization of the longer wavelength part of the electromagnetic spectrum may be advantageous due to its relatively low interference. The environmental and process monitoring applications of this spectral region may be especially advantageous if semiconductor lasers are utilized as light sources. Laser diodes have all the properties of other types of lasers with the added benefits of compactness, low power consumption, low cost and long lifetime. However, to utilize this spectral region for environmental or process monitoring applications, appropriate near-infrared (NIR) absorbing probe molecules need to be employed. These probes may be used to determine analytical properties important for environmental or process monitoring applications, e.g., pH, oxygen concentration, metal ion determinations, solvent hydrophobicity, just to mention a few. These NIR probes may be incorporated into polymers to form a stable probe arrangement for convenient monitoring using semiconductor lasers. The utility can be further enhanced using fiber optics. In this paper the use of MR absorption and fluorescence spectroscopy for monitoring applications will be demonstrated.

  11. Food monitoring based on diode laser gas spectroscopy

    NASA Astrophysics Data System (ADS)

    Lewander, M.; Guan, Z. G.; Persson, L.; Olsson, A.; Svanberg, S.

    2008-11-01

    Food is frequently packed in a controlled environment of gas, in order to extend shelf life. It is of great importance to be able to monitor the status of the packed food to ensure quality. We demonstrate a technique to monitor the gas inside packages non-intrusively by using a laser spectroscopic method in scattering solid materials. The technique named GASMAS (GAs in Scattering Media Absorption Spectroscopy) is based on tunable diode laser absorption spectroscopy and relies on the fact that free gas inside solid materials absorbs much sharper spectrally than the bulk material. Results from time dependent measurements of molecular oxygen and water vapour in packages of minced meat, bake-off bread, and the headspace of a milk carton are presented. We show that the technique allows gas measurements inside the food through the package, and assessment of the integrity of the package.

  12. 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.

  13. 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.

  14. 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.

  15. Discretely tunable multiwavelength diode-pumped Nd:YALO laser

    NASA Astrophysics Data System (ADS)

    Poirier, P.; Hanson, F.

    1996-01-01

    Operation of a moderate-to-high repetition-rate Q-switched quadrupled diode-pumped Nd:YALO laser discretely tunable between 266 and 275 nm is reported. Intracavity frequency doubling of the fundamental yielded 5.4 and 4.4 mJ at 532 and 550 nm, respectively, at a 600-Hz repetition rate. The laser radiation was frequency quadrupled to the UV external to the cavity with an output of 0.28 and 0.24 mJ at 266 and 275 nm, respectively. Astigmatic focal lengths that are due to thermal lensing effects of the Nd:YALO rod in the side-pumping geometry are presented.

  16. Tissue Necrosis Following Diode Laser-Assisted Transcanalicular Dacryocystorhinostomy

    PubMed Central

    McClintic, Scott M.; Yoon, Michael K.; Bidar, Maziar; Dutton, Jonathan J.; Vagefi, M. Reza; Kersten, Robert C.

    2012-01-01

    Advantages of transcanalicular laser-assisted dacryocystorhinostomy (TCDCR) over conventional external and endonasal dacryocystorhinostomy (DCR) have been purported to include decreased operating time, reduced morbidity, enhanced cosmesis, avoidance of general anesthesia, and a shorter recovery time. However, one case of skin necrosis has recently been reported to have occurred following diode laser-assisted TCDCR, and we now report three additional cases that were evaluated by the Ophthalmic Plastic Surgery services at the University of North Carolina and the University of California, San Francisco. Three patients developed full-thickness tissue necrosis over the medial canthus following TCDCR, and two of these patients experienced persistent tissue breakdown at the site following reconstructive repair. PMID:24807803

  17. 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.

  18. Multicomponent gas analyzers based on tunable diode lasers

    SciTech Connect

    Stepanov, E.V.; Zyrianov, P.V.; Khusnutdinov, A.N.; Kouznetsov, A.I.; Ponurovskii, Y.Ya.

    1996-12-31

    A family of multicomponent gas analyzers based on tunable diode lasers (TDL) are presented including: an open optical path 3-component gas analyzer for monitoring atmosphere pollution; a 4-gas component analyzer with a multipass cell, a multichannel TDL system with multipass cell and MIR fiber optics delivery, and a multichannel TDL analyzer for breath content gas analysis. A4B6 tunable diode lasers of different spectral region from 4 to 12 micron were used in every channel of the analyzers to obtain atmospheric transmission spectra and to measure concentration of studied gases. Main gaseous atmospheric pollutants like CO, NO, NH{sub 3}, CH{sub 4}, SO{sub 2}, etc. and some of breath gases could be measured at ppb concentration level in real time with these systems depending on customers requirements. The analyzers are driven by IBM compatible PC. The first results on field monitoring tests as well as on their application to human exhalation content analysis and human exposure monitoring are presented.

  19. TOPICAL REVIEW: InGaN-based violet laser diodes

    NASA Astrophysics Data System (ADS)

    Nakamura, S.

    1999-06-01

    High-efficiency light-emitting diodes emitting amber, green, blue and ultraviolet light have been obtained through the use of InGaN active layers instead of GaN active layers. The localized energy states caused by In composition fluctuation in the InGaN active layer seem to be related to the high efficiency of the InGaN-based emitting devices. Long-lifetime violet InGaN multi-quantum-well/GaN/AlGaN separate-confinement heterostructure laser diodes (LDs) were successfully fabricated using epitaxially laterally overgrown GaN by reducing a large number of threading dislocations originating from the interface between GaN and sapphire substrate. The threading dislocations shorten the lifetime of the LDs through an increase of the threshold current density. The LDs with cleaved mirror facets showed an output power as high as 30 mW under room-temperature continuous-wave (CW) operation with a stable fundamental transverse mode. The lifetime of the LDs at a constant output power of 5 mW was estimated to be approximately 3000 h under CW operation at an ambient temperature of 50 °C. These results indicate that these LDs already can be used for many real applications, such as digital versatile disks, laser printers, sensors and exciting light sources as a commercial product with a high output power and a high reliability.

  20. Laser-induced electron source in a vacuum diode

    NASA Astrophysics Data System (ADS)

    Ghera, U.; Boxman, R. L.; Kleinman, H.; Ruschin, S.

    1989-11-01

    Experiments were conducted in which a high-power CO2 TEA laser interacted with metallic cathode in a high-vacuum (10 to the -8th Torr) diode. For power densities lower than 5 x 10 to the 7th W/sq cm, no current was detected. For power densities in the range of 5 x 10 to the 7th to 5 x 10 to the 8th W/sq cm, the Cu cathode emitted a maximum current of 40 mA. At a higher power density level, a circuit-limited current of 8 A was detected. The jump of a few orders of magnitude in the current is attributed to breakdown of the diode gap. The experimental results are similar to those of a triggered vacuum gap, and a thorough comparison is presented in this paper. The influence of the pressure in the vacuum chamber on the current magnitude shows the active role that adsorbed gas molecules have in the initial breakdown. When the cathode material was changed from metal to metal oxide, much lower laser power densities were required to reach the breakdown current region.

  1. 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.

  2. 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.

  3. Laser Boronizing of Stainless Steel with Direct Diode Laser

    NASA Astrophysics Data System (ADS)

    Kusuhara, Takayoshi; Morimoto, Junji; Abe, Nobuyuki; Tsukamoto, Masahiro

    Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050°C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of stainless steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope, electron probe micro analyser(EPMA) and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of NiB, CrB, FeB and Fe2B, and get wear resistance.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications such as underwater communications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries.

  8. Shifted excitation Raman difference spectroscopy using a dual-wavelength DBR diode laser at 785 nm

    NASA Astrophysics Data System (ADS)

    Maiwald, M.; Eppich, B.; Fricke, J.; Ginolas, A.; Bugge, F.; Klehr, A.; Sumpf, B.; Erbert, G.; Tränkle, G.

    2015-03-01

    The application of shifted excitation Raman difference spectroscopy (SERDS) using a dual wavelength distributed Bragg reflector (DBR) diode laser at 785 nm will be presented. Both excitation wavelengths necessary for SERDS provide an optical power of more than 160 mW in continuous wave operation. Raman experiments are carried out and demonstrate the suitability of the excitation light source for SERDS. Moreover, a dual-wavelength master-oscillator power amplifier diode laser system is presented. The diode laser system reaches optical powers larger 750 mW while the spectral properties of the dual-wavelength laser remain unchanged.

  9. 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

  10. Continuous wave laser generation at 1064 nm in femtosecond laser inscribed Nd:YVO4 channel waveguides

    NASA Astrophysics Data System (ADS)

    Tan, Yang; Chen, Feng; Vázquez de Aldana, J. R.; Torchia, G. A.; Benayas, A.; Jaque, D.

    2010-07-01

    We report on continuous wave 1064 nm laser generation from an ultrafast laser inscribed neodymium-doped yttrium orthovanadate channel waveguide with pumping at 808 nm. Single-mode stable laser operations have been observed with pump powers at threshold as low as 14 mW and with laser slope efficiencies as high as 38.7%.

  11. 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.

  12. 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.

  13. 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

  14. 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)

  15. 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.

  16. 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)

  17. Laser-diode pumped 40-W Yb:YAG ceramic laser.

    PubMed

    Hao, Qiang; Li, Wenxue; Pan, Haifeng; Zhang, Xiaoyi; Jiang, Benxue; Pan, Yubai; Zeng, Heping

    2009-09-28

    We demonstrated a high-power continuous-wave (CW) polycrystalline Yb:YAG ceramic laser pumped by fiber-pigtailed laser diode at 968 nm with 400 mum fiber core. The Yb:YAG ceramic laser performance was compared for different Yb(3+) ion concentrations in the ceramics by using a conventional end-pump laser cavity consisting of two flat mirrors with output couplers of different transmissions. A CW laser output of 40 W average power with M(2) factor of 5.8 was obtained with 5 mol% Yb concentration under 120 W incident pump power. This is to the best of our knowledge the highest output power in end-pumped bulk Yb:YAG ceramic laser. PMID:19907559

  18. 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.

  19. Diode-laser-pumped Nd:YAG laser injection seeding system.

    PubMed

    Schmitt, R L; Rahn, L A

    1986-03-01

    We have designed and tested a compact injection seeding system consisting of a diode-laser-pumped Nd:YAG master oscillator and a permanent-magnet Faraday isolator. With active resonator frequency stabilization, this system permits highly reliable single-axial-mode operation of a Q-switched Nd:YAG laser over a period of hours. The system is capable of injection seeding both stable and unstable resonator designs and is suitable for injection seeding commercial lasers with only minor modifications. PMID:18231224

  20. 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

  1. Ultralow detection limits for an organic dye determined by fluorescence spectroscopy with laser diode excitation

    SciTech Connect

    Johnson, P.A.; Barber, T.E.; Smith, B.W.; Winefordner, J.D. )

    1989-04-15

    Fluorescence of IR-140, a laser dye in methanol solution, is excited by a semiconductor laser diode. Analytical figures of merit are compared for three different instrumental configurations, with the dye measured in a cuvette, a liquid jet, and a compact instrument. The best limit of detection, 46,000 molecules, was achieved with a liquid jet. Linear dynamic range was 6 orders of magnitude. The laser diode operates in the near-infrared region, resulting in low background fluorescence.

  2. 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)

  3. 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)

  4. Mode locking of diode- and flashlamp-pumped Nd:YAG lasers using semiconductor saturable absorbers

    NASA Astrophysics Data System (ADS)

    Dombrovsky, Andrej; Kubecek, Vaclav; Zvonicek, K.; Diels, Jean-Claude M.; Stintz, Andreas

    2003-07-01

    Operation of laser diode and flash lamp pumped Nd:YAG lasers mode locked with two different types of semiconductor saturable absorbers is reported. In the first type that is used mainly in diode pumped systems the absorber layers are integrated on highly reflective Bragg mirror. The second type is for use in transmission mode inside the resonator. Different design of semiconductor elements, pumping geometries and resonator configurations were investigated and characteristics of laser operation in mode-locked regime are presented.

  5. Effects of polarization in low-level laser therapy of spinal cord injury in rats

    NASA Astrophysics Data System (ADS)

    Ando, Takahiro; Sato, Shunichi; Kobayashi, Hiroaki; Nawashiro, Hiroshi; Ashida, Hiroshi; Hamblin, Michael R.; Obara, Minoru

    2012-03-01

    Low-level laser therapy (LLLT) is a promising approach to treat the spinal cord injury (SCI). Since nerve fibers have optical anisotropy, propagation of light in the spinal tissue might be affected by its polarization direction. However, the effect of polarization on the efficacy of LLLT has not been elucidated. In the present study, we investigated the effect of polarization on the efficacy of near-infrared LLLT for SCI. Rat spinal cord was injured with a weight-drop device. The lesion site was irradiated with an 808-nm diode laser beam that was transmitted through a polarizing filter immediately after injury and daily for five consecutive days. The laser power at the injured spinal cord surface was 25 mW, and the dosage per day was 9.6 J/cm2 (spot diameter, 2 cm; irradiation duration, 1200 s). Functional recovery was assessed daily by an open-field test. The results showed that the functional scores of the SCI rats that were treated with 808-nm laser irradiation were significantly higher than those of the SCI alone group (Group 1) from day 5 after injury, regardless of the polarization direction. Importantly, as compared to the locomotive function of the SCI rats that were treated with the perpendicularly-polarized laser parallel to the spinal column (Group 2), that of the SCI rats that were irradiated with the linearly aligned polarization (Group 3) was significantly improved from day 10 after injury. In addition, the ATP contents in the injured spinal tissue of Group 3, which were measured immediately after laser irradiation, were moderately higher than those of Group 2. These observations are attributable to the deeper penetration of the parallelpolarized light in the anisotropic spinal tissue, suggesting that polarization direction significantly affects the efficacy of LLLT for SCI.

  6. 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

  7. High Power Diode Pumped 1.06 Micron Solid State Laser

    NASA Astrophysics Data System (ADS)

    Arvind, Mukundarajan A.; Martin, Dan W.; Osterhage, R. J.

    1989-07-01

    Diode pumped solid state lasers have been attracting significant interest in recent years due to advances in high power semiconductor diode lasers. They offer considerable advantages over flashlamp pumped lasers such as compact size, high efficiency, lower heat dissipation and solid-state reliability. In this paper, we report on the results of a Nd:YAG laser, transverse pumped by diode laser arrays. We have measured an output power of 1.14 Watts at 1.06 microns with a laser diode power consumption of 40 Watts. This represents the highest reported electrical efficiency (2.85%) for a transverse pumped, CW, TEM00 laser. The diode arrays were selected and tuned to emit at wavelengths close to the peak neodymium absorption line at 0.808 microns with Peltier coolers. Two diode laser bars side pumped a 20 mm long, 1.5 mm diameter Nd:YAG laser rod. The optical cavity is 13.8 cm long consisting of a high reflectivity mirror and a 95% reflectivity output mirror. The output beam divergence was measured to be near diffraction limited at 1.4 milliradians, and the beam diameter was 1 mm.

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

    SciTech Connect

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

    1994-01-01

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

  9. Three-dimensional dynamics of temperature fields in phantoms and biotissue under IR laser photothermal therapy using gold nanoparticles and ICG dye

    NASA Astrophysics Data System (ADS)

    Akchurin, Georgy G.; Garif, Akchurin G.; Maksimova, Irina L.; Skaptsov, Alexander A.; Terentyuk, Georgy S.; Khlebtsov, Boris N.; Khlebtsov, Nikolai G.; Tuchin, Valery V.

    2010-02-01

    We describe applications of silica (core)/gold (shell) nanoparticles and ICG dye to photothermal treatment of phantoms, biotissue and spontaneous tumor of cats and dogs. The laser irradiation parameters were optimized by preliminary experiments with laboratory rats. Three dimensional dynamics of temperature fields in tissue and solution samples was measured with a thermal imaging system. It is shown that the temperature in the volume region of nanoparticles localization can substantially exceed the surface temperature recorded by the thermal imaging system. We have demonstrated effective optical destruction of cancer cells by local injection of plasmon-resonant gold nanoshells and ICG dye followed by continuous wave (CW) diode laser irradiation at wavelength 808 nm.

  10. Growth, spectroscopic properties and laser performance near 2 μM of Tm3+/Ho3+: SrGdGa3O7 crystal

    NASA Astrophysics Data System (ADS)

    Xia, Houping; Feng, Jianghe; Xu, Jinlong; You, Zhenyu; Wang, Yan; Tu, Chaoyang

    2015-04-01

    The Tm3+/Ho3+: SrGdGa3O7 single crystal was grown by the Czochralski method. The polarized absorption spectra, emission spectra and fluorescence decay curves of the crystal were measured. The crystal exhibited a broad absorption band and a broad emission band, as well as a fluorescence lifetime of 5I7 multiplet of Ho3+ ions up to 8.0 ms. End-pumped by a fiber-coupled diode laser at 808 nm, the laser operation around 2.0 μm has been realized with the a-cut and c-cut crystal samples. The maximum output power is 200 mW when a-cut crystal sample was employed.

  11. 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.

  12. 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.

  13. Ash characteristics in controlled diode laser pyrolysis of chlorinated rubber

    NASA Astrophysics Data System (ADS)

    Peligrad, A. A.; Schmidt, M. J. J.; Li, L.; Spencer, J. T.

    2000-02-01

    This paper describes the effects of 60 W High Power Diode Laser (HPDL) beams on the removal of chlorinated rubber (CR) paint from concrete surfaces and the ash particles generated from this process. The physical characteristics, including shape and size distribution of the removed and collected airborne CR particles, down to a size of around 1 μm in diameter, were determined using optical microscopy and image analysis. The shape of the particles observed was highly irregular, displaying no symmetry. The size distribution of the collected particles was found to range between 1-2000 μm, with the maximum concentration being found between 29 and 60 μm. The chemical characteristics of the CR ash particles were investigated by means of ESEM and EDX techniques. From a comparative analysis, it was found that the concentration of chlorine within the CR material was significantly reduced after HPDL treatment. This, together with DTA/TGA results indicated a combustive degradation of the CR polymer through the interaction with the process gas, oxygen, and the laser irradiation. Also, a strong correlation between laser power and average particle sizes has been found, with higher powers generally producing larger particle sizes. Opposite effects have been found by changing the oxygen flow rate, with higher oxygen flow producing, on average, smaller particles. An interpretation of the combustion process, as well as a brief discussion on operational safety and environmental impact of the products is attempted.

  14. Posthaste Outgrow of Lip Pyogenic Granuloma after Diode Laser Removal

    PubMed Central

    Asnaashari, Mohammad; Bigom-Taheri, Jamile; Mehdipoor, Maesoome; Bakhshi, Mahin

    2014-01-01

    Introduction: Pyogenic granuloma (PG) is one of the inflammatory hyperplasia seen in the oral cavity. It is a reactional response to minor trauma or chronic irritation and also might be related to hormonal changes. Rarely, PG occurs extragingivally.The most common treatment of PG is surgical excision but alternative approaches such as laser excision have also been proposed. Case report: Herein, we present a case of lip pyogenic granuloma in a 15-year-old male whom had been under orthodontic treatment. The lesion was first excised with diode laser as a conservative method, but the lesion had immediately recurred and was excised with surgical blade as the traditional method. No recurrence or scarring was observed in 6 months follow-up. Results and conclusion: Although the use of laser as modern medicine offers a new tool for treatment of oral lesions, scalpel (blade) surgical excision still seems to be the successful treatment of choice in minimizing the recurrence of lesion especially when exacerbating factors such as hormonal imbalances exist. PMID:25653806

  15. 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.

  16. 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.

  17. 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.

  18. Tunable Diode Laser Applications To Cigarette Smoke Analysis

    NASA Astrophysics Data System (ADS)

    Vilcins, Gunars; Harward, Charles N.; Parrish, Milton E.; Forrest, Gary T.

    1983-11-01

    High resolution infrared tunable diode laser spectroscopy (TDL) has been applied to the study of cigarette smoke for qualitative and quantitative determinations involved in tobacco blend and cigarette filter developments. As examples of the different types of application of this work, several TDL studies are presented. The measurements of smoke components on a puff-by-puff basis in confined sample chambers and flowing streams were used to study the smoke component deliveries and the effects of filter dilution. The study of isotopes generated during combustion of chemically treated tobaccos was another application of the TDL system to complex gas mixtures without prior separation of compo-nents. The application of the TDL to the study of cigarette filters and smoke delivery simultaneously was demonstrated by using two well resolved absorption lines of two different gases which occur on a single TDL wavelength scan.

  19. 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.

  20. 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.