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Sample records for nm laser transition

  1. Hydrocarbon-free resonance transition 795-nm rubidium laser

    SciTech Connect

    Wu, S Q; Soules, T F; Page, R H; Mitchell, S C; Kanz, V K; Beach, R J

    2008-01-09

    An optical resonance transition rubidium laser (5{sup 2}P{sub 1/2} {yields} 5{sup 2}S{sub 1/2}) is demonstrated with a hydrocarbon-free buffer gas. Prior demonstrations of alkali resonance transition lasers have used ethane as either the buffer gas or a buffer gas component to promote rapid fine-structure mixing. However, our experience suggests that the alkali vapor reacts with the ethane producing carbon as one of the reaction products. This degrades long term laser reliability. Our recent experimental results with a 'clean' helium-only buffer gas system pumped by a Ti:sapphire laser demonstrate all the advantages of the original alkali laser system, but without the reliability issues associated with the use of ethane.

  2. A compact ultranarrow high-power laser system for experiments with 578 nm ytterbium clock transition

    SciTech Connect

    Cappellini, G.; Lombardi, P.; Mancini, M.; Pagano, G.; Pizzocaro, M.; Fallani, L.; Catani, J.

    2015-07-15

    In this paper, we present the realization of a compact, high-power laser system able to excite the ytterbium clock transition at 578 nm. Starting from an external-cavity laser based on a quantum dot chip at 1156 nm with an intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of visible light at 578 nm via frequency doubling. The laser is locked with a 500 kHz bandwidth to an ultra-low-expansion glass cavity stabilized at its zero coefficient of thermal expansion temperature through an original thermal insulation and correction system. This laser allowed the observation of the clock transition in fermionic {sup 173}Y b with a <50 Hz linewidth over 5 min, limited only by a residual frequency drift of some 0.1 Hz/s.

  3. Resonance transition 795-nm Rubidium laser using 3He buffer gas

    SciTech Connect

    Wu, S S; Soules, T F; Page, R H; Mitchell, S C; Kanz, V K; Beach, R J

    2007-08-02

    We report the first demonstration of a 795-nm Rubidium resonance transition laser using a buffer gas consisting of pure {sup 3}He. This follows our recent demonstration of a hydrocarbon-free 795-nm Rubidium resonance laser which used naturally-occurring He as the buffer gas. Using He gas that is isotopically enriched with {sup 3}He yields enhanced mixing of the Rb fine-structure levels. This enables efficient lasing at reduced He buffer gas pressure, improving thermal management in high average power Rb lasers and enhancing the power scaling potential of such systems.

  4. A Faraday laser lasing on Rb 1529 nm transition.

    PubMed

    Chang, Pengyuan; Peng, Huanfa; Zhang, Shengnan; Chen, Zhangyuan; Luo, Bin; Chen, Jingbiao; Guo, Hong

    2017-08-21

    We present the design and performance characterization of a Faraday laser directly lasing on the Rb 1529 nm transition (Rb, 5P 3/2 - 4D 5/2) with high stability, narrow spectral linewidth and low cost. This system does not need an additional frequency-stabilized pump laser as a prerequisite to preparing Rb atom from 5S to 5P excited state. Just by using a performance-improved electrodeless discharge lamp-based excited-state Faraday anomalous dispersion optical filter (LESFADOF), we realized a heterogeneously Faraday laser with the frequency corresponding to atomic transition, working stably over a range of laser diode (LD) current from 85 mA to 171 mA and the LD temperature from 11 °C to 32 °C, as well as the 24-hour long-term frequency fluctuation range of no more than 600 MHz. Both the laser linewidth and relative intensity noisy (RIN) are measured. The Faraday laser lasing on Rb 1529 nm transition (telecom C-band) can be applied to further research on metrology, microwave photonics and optical communication systems. Besides, since the transitions correspongding to the populated excited-states of alkali atoms within lamp are extraordinarily rich, this scheme can increase the flexibility for choosing proper wavelengths for Faraday laser and greatly expand the coverage of wavelength corresponding to atomic transmission for laser frequency stabilization.

  5. Study of transitions in thulium atoms in the 410-420-nm range for laser cooling

    SciTech Connect

    Akimov, A V; Chebakov, K Yu; Tolstikhina, I Yu; Sokolov, A V; Rodionov, P B; Kanorsky, S I; Sorokin, V N; Kolachevsky, N N

    2008-10-31

    The possibility of laser cooling of thulium atoms is considered. The hyperfine structure of almost cyclic 4f{sup 13}6s{sup 2} (J{sub g} = 7/2) {r_reversible} 4f{sup 12}5d{sub 3/2}6s{sup 2} (J{sub e} = 9/2) and 4f{sup 13}6s{sup 2} (J{sub g} = 7/2) {r_reversible} 4f{sup 12}5d{sub 5/2}6s{sup 2} (J{sub e} = 9/2) transitions at 410.6 and 420.4 nm, respectively, is studied by the method of sub-Doppler saturation spectroscopy in counterpropagating laser beams. The hyperfine splitting of excited levels involved in these transitions is measured and the natural linewidths of these transitions are determined. The structure of the neighbouring 4f{sup 13}6s6p (J{sub e} = 5/2) and 4f{sup 12}5d{sub 5/2}6s{sup 2} (J{sub e} = 7/2) levels is studied for the first time by this method. The decay probabilities of the J{sub e} = 9/2 levels via channels removing atoms from the cooling cycle are calculated. It is found that the branching ratio for the strong transition at 410.6 nm (A = 6x10{sup 7} s{sup -1}) is smaller than 2x10{sup -5}, which makes this transition most promising for laser cooling. The laser cooling of atoms in a Zeeman cooler at this transition is simulated. The possibility of using a laser-cooled cloud of thulium atoms to study the metrological transition at 1.14 {mu}m is discussed. (laser cooling of atoms)

  6. Frequency stabilization of a 1083 nm fiber laser to {sup 4}He transition lines with optical heterodyne saturation spectroscopies

    SciTech Connect

    Gong, W.; Peng, X. Li, W.; Guo, H.

    2014-07-15

    Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable {sup 4}He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10{sup −12}@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

  7. Frequency stabilization of a 1083 nm fiber laser to 4He transition lines with optical heterodyne saturation spectroscopies

    NASA Astrophysics Data System (ADS)

    Gong, W.; Peng, X.; Li, W.; Guo, H.

    2014-07-01

    Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable 4He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to its flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10-12@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.

  8. 469nm Fiber Laser Source

    SciTech Connect

    Drobshoff, A; Dawson, J W; Pennington, D M; Payne, S A; Beach, R

    2005-01-20

    We have demonstrated 466mW of 469nm light from a frequency doubled continuous wave fiber laser. The system consisted of a 938nm single frequency laser diode master oscillator, which was amplified in two stages to 5 Watts using cladding pumped Nd{sup 3+} fiber amplifiers and then frequency doubled in a single pass through periodically poled KTP. The 3cm long PPKTP crystal was made by Raicol Crystals Ltd. with a period of 5.9 {micro}m and had a phase match temperature of 47 degrees Centigrade. The beam was focused to a 1/e{sup 2} diameter in the crystal of 29 {micro}m. Overall conversion efficiency was 11% and the results agreed well with standard models. Our 938nm fiber amplifier design minimizes amplified spontaneous emission at 1088nm by employing an optimized core to cladding size ratio. This design allows the 3-level transition to operate at high inversion, thus making it competitive with the 1088nm 4-level transition. We have also carefully chosen the fiber coil diameter to help suppress propagation of wavelengths longer than 938 nm. At 2 Watts, the 938nm laser had an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >10:1).

  9. 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.

  10. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm

    PubMed Central

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-01-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t0.66 [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards. PMID:27231639

  11. Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

    PubMed

    Tao, Zhiming; Hong, Yelong; Luo, Bin; Chen, Jingbiao; Guo, Hong

    2015-09-15

    We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

  12. Demonstration of saturated tabletop soft x-ray lasers at 5 Hz repetition rate in transitions of Ne-like ions with wavelengths near 30 nm

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Shlyaptsev, Vyacheslav N.; Rocca, Jorge J.

    2005-10-01

    Recent experiments have demonstrated that the laser pump energy required to operate collisional soft x-ray lasers in the gain saturated regime can be significantly reduced by directing the heating pulse into the plasma at grazing incidence for a more efficient energy deposition [1-2]. Optimization of the incidence angle led to gain-saturated operation at 5Hz repetition rate in several transitions of Ni-like ions at wavelengths ranging from 18.9nm to 13.2nm [3]. We report saturated high repetition rate laser-pumped table-top soft x-ray lasers in Ne-like ions at wavelengths near 30nm. Gain-saturated lasers operating at 5Hz repetition rate were obtained in Ne-like Ti at 32.6nm and in Ne-like V at 30.4nm heating plasmas with laser pulses of ˜1J and 8ps impinging at 20^o grazing incidence. Average powers > 1μW were measured. Strong lasing was also observed in Ne-like Cr at 28.6nm. 1. R. Keenan et al, Phys. Rev. Lett., 94, 103901, (2005). 2. B. M. Luther et al, Opt. Lett., 30, 165, (2005). 3. Y. Wang et al, submitted to Phys. Rev. A, (2005).

  13. Low intensity 635 nm diode laser irradiation inhibits fibroblast-myofibroblast transition reducing TRPC1 channel expression/activity: New perspectives for tissue fibrosis treatment.

    PubMed

    Sassoli, Chiara; Chellini, Flaminia; Squecco, Roberta; Tani, Alessia; Idrizaj, Eglantina; Nosi, Daniele; Giannelli, Marco; Zecchi-Orlandini, Sandra

    2016-03-01

    Low-level laser therapy (LLLT) or photobiomodulation therapy is emerging as a promising new therapeutic option for fibrosis in different damaged and/or diseased organs. However, the anti-fibrotic potential of this treatment needs to be elucidated and the cellular and molecular targets of the laser clarified. Here, we investigated the effects of a low intensity 635 ± 5 nm diode laser irradiation on fibroblast-myofibroblast transition, a key event in the onset of fibrosis, and elucidated some of the underlying molecular mechanisms. NIH/3T3 fibroblasts were cultured in a low serum medium in the presence of transforming growth factor (TGF)-β1 and irradiated with a 635 ± 5 nm diode laser (continuous wave, 89 mW, 0.3 J/cm(2) ). Fibroblast-myofibroblast differentiation was assayed by morphological, biochemical, and electrophysiological approaches. Expression of matrix metalloproteinase (MMP)-2 and MMP-9 and of Tissue inhibitor of MMPs, namely TIMP-1 and TIMP-2, after laser exposure was also evaluated by confocal immunofluorescence analyses. Moreover, the effect of the diode laser on transient receptor potential canonical channel (TRPC) 1/stretch-activated channel (SAC) expression and activity and on TGF-β1/Smad3 signaling was investigated. Diode laser treatment inhibited TGF-β1-induced fibroblast-myofibroblast transition as judged by reduction of stress fibers formation, α-smooth muscle actin (sma) and type-1 collagen expression and by changes in electrophysiological properties such as resting membrane potential, cell capacitance and inwardly rectifying K(+) currents. In addition, the irradiation up-regulated the expression of MMP-2 and MMP-9 and downregulated that of TIMP-1 and TIMP-2 in TGF-β1-treated cells. This laser effect was shown to involve TRPC1/SAC channel functionality. Finally, diode laser stimulation and TRPC1 functionality negatively affected fibroblast-myofibroblast transition by interfering with TGF-β1 signaling, namely reducing the

  14. Multi-watt 589nm fiber laser source

    NASA Astrophysics Data System (ADS)

    Dawson, Jay W.; Drobshoff, Alex D.; Beach, Raymond J.; Messerly, Michael J.; Payne, Stephen A.; Brown, Aaron; Pennington, Deanna M.; Bamford, Douglas J.; Sharpe, Scott J.; Cook, David J.

    2006-02-01

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichio-metric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd 3+ fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the 1088nm 4-level laser transition. At 15W, the 938nm laser has an M2 of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  15. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  16. Compact Fiber Laser for 589nm Laser Guide Star Generation

    NASA Astrophysics Data System (ADS)

    Pennington, D.; Drobshoff, D.; Mitchell, S.; Brown, A.

    Laser guide stars are crucial to the broad use of astronomical adaptive optics, because they facilitate access to a large fraction of possible locations on the sky. Lasers tuned to the 589 nm atomic sodium resonance can create an artificial beacon at altitudes of 95-105 km, thus coming close to reproducing the light path of starlight. The deployment of multiconjugate adaptive optics on large aperture telescopes world-wide will require the use of three to nine sodium laser guide stars in order to achieve uniform correction over the aperture with a high Strehl value. Current estimates place the minimum required laser power at > 10 W per laser for a continuous wave source, though a pulsed format, nominally 6?s in length at ~ 16.7 kHz, is currently preferred as it would enable tracking the laser through the Na layer to mitigate spot elongation. The lasers also need to be compact, efficient, robust and turnkey. We are developing an all-fiber laser system for generating a 589 nm source for laser-guided adaptive optics. Fiber lasers are more compact and insensitive to alignment than their bulk laser counterparts, and the heat-dissipation characteristics of fibers, coupled with the high efficiencies demonstrated and excellent spatial mode characteristics, make them a preferred candidate for many high power applications. Our design is based on sum-frequency mixing an Er/Yb:doped fiber laser operating at 1583 nm with a 938 nm Nd:silica fiber laser in a periodically poled crystal to generate 589 nm. We have demonstrated 14 W at 1583 nm with an Er/Yb:doped fiber laser, based on a Koheras single frequency fiber oscillator amplified in an IPG Photonics fiber amplifier. The Nd:silica fiber laser is a somewhat more novel device, since the Nd3+ ions must operate on the resonance transition (i.e. 4F3/2-4I9/2), while suppressing ASE losses at the more conventional 1088 nm transition. Optimization of the ratio of the fiber core and cladding permits operation of the laser at room

  17. Gain and continuous-wave laser oscillation on the 1315 nm atomic iodine transition pumped by an air-helium electric discharge

    NASA Astrophysics Data System (ADS)

    Woodard, B. S.; Zimmerman, J. W.; Benavides, G. F.; Carroll, D. L.; Verdeyen, J. T.; Palla, A. D.; Field, T. H.; Solomon, W. C.; Davis, S. J.; Rawlins, W. T.; Lee, S.

    2008-07-01

    Herein the authors report on the demonstration of gain and a continuous-wave laser on the 1315nm transition of atomic iodine using the energy transferred to I(P1/22) from O2(aΔ1) produced by a radio-frequency-excited electric discharge sustained in a dry air-He-NO gas mixture. Active oxygen and nitrogen species were observed downstream of the discharge region. Downstream of the discharge, cold gas injection was employed to raise the gas density and lower the temperature of the continuous gas flow. Gain of 0.0062%cm-1 was obtained and the laser output power was 32mW in a supersonic flow cavity.

  18. Atomic frequency reference at 1033 nm for ytterbium (Yb)-doped fiber lasers and applications exploiting a rubidium (Rb) 5S_1/2 to 4D_5/2 one-colour two-photon transition

    NASA Astrophysics Data System (ADS)

    Roy, Ritayan; Condylis, Paul C.; Johnathan, Yik Jinen; Hessmo, Björn

    2017-04-01

    We demonstrate a two-photon transition of rubidium (Rb) atoms from the ground state (5$S_{1/2}$) to the excited state (4$D_{5/2}$), using a home-built ytterbium (Yb)-doped fiber amplifier at 1033 nm. This is the first demonstration of an atomic frequency reference at 1033 nm as well as of a one-colour two-photon transition for the above energy levels. A simple optical setup is presented for the two-photon transition fluorescence spectroscopy, which is useful for frequency stabilization for a broad class of lasers. This spectroscopy has potential applications in the fiber laser industry as a frequency reference, particularly for the Yb-doped fiber lasers. This two-photon transition also has applications in atomic physics as a background- free high- resolution atom detection and for quantum communication, which is outlined in this article.

  19. Watt-level narrow-linewidth Nd:YAG laser operating on 4F3/2→4I15/2 transition at 1834 nm.

    PubMed

    Xu, Bin; Wang, Yi; Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Luo, Zhengqian; Xu, Huiying; Cai, Zhiping; Moncorgé, Richard

    2016-02-22

    We report on a 808 nm diode-pumped Nd:YAG narrow linewidth laser at 1834.25 nm using a compact two-mirror linear cavity. In free-running mode, a maximum output power of 1.10 W is obtained with a slope efficiency of about 11.1% at a cooling temperature of the laser crystal of 18°C. Decreasing this temperature down to 8°C increases the output power linearly up to 1.31 W. Shortening the laser cavity reduces the output power down to about 0.70 W but on a single longitudinal mode. These laser results represent the best laser performance ever achieved with any Nd-doped bulk material in the 1.8 µm mid-infrared spectral range.

  20. 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.

  1. A 729 nm laser with ultra-narrow linewidth for probing 4S 1/2-3D 5/2 clock transition of 40Ca +

    NASA Astrophysics Data System (ADS)

    Guan, Hua; Liu, Qu; Huang, Yao; Guo, Bin; Qu, Wancheng; Cao, Jian; Huang, Guilong; Huang, Xueren; Gao, Kelin

    2011-01-01

    A Coherent Inc. Ti:sapphire laser MBR-110 is locked to a temperature-controlled high finesse Fabry-Perot cavity supported on an isolated platform. The linewidth is measured by locking the laser to another similar super-cavity at the same time and the heterodyne beatnote between two laser beams that locked to different cavities determines the linewidth. The result shows that the laser's linewidth is suppressed to be 41 Hz. The long-term drift is measured with a femtosecond comb and determined to be ~ 0.1 Hz/s. This laser is used to probe the 4S 1/2-3D 5/2 clock transition of a single 40Ca + ion. The Zeeman components of the clock transition with a linewidth of 160 Hz have been observed.

  2. Diode-pumped continuous-wave Nd:LuVO4 laser emitting at 1089 nm based on the 4F(3/2)-4I(11/2) transition.

    PubMed

    Lü, Yanfei; Zhang, Xihe; Xia, Jing; Fu, Xinhua

    2010-07-10

    We present what is, to the best of our knowledge, the first diode-pumped Nd:LuVO(4) laser emitting at 1089 nm, based on the (4)F(3/2)-(4)I(11/2) transition, generally used for a 1066 nm emission. A power of 8.7 W at 1089 nm has been achieved in continuous-wave (cw) operation with a fiber-coupled laser diode emitting 18.7 W at 809 nm. Intracavity second-harmonic generation in cw mode has also been demonstrated with a power of 3.6 W at 544.5 nm by using a LiB(3)O(5) nonlinear crystal.

  3. 308nm Excimer Laser in Dermatology

    PubMed Central

    Mehraban, Shadi

    2014-01-01

    308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

  4. High Power 938nm Cladding Pumped Fiber Laser

    SciTech Connect

    Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D; Taylor, L; Hackenberg, W; Bonaccini, D

    2002-12-26

    We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel, which permitted near complete suppression of amplified spontaneous emission at 1088nm. We are presently seeking to scale the output of this laser to 10W. We will discuss the fiber and laser design issues involved in scaling the laser to the 10W power level and present our most recent results.

  5. Laser damage database at 1064 nm

    SciTech Connect

    Rainer, F.; Gonzales, R.P.; Morgan, A.J.

    1990-03-01

    In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs.

  6. Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Xia, Jing; Liu, Huilong; Pu, Xiaoyun

    2014-10-01

    We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.

  7. Efficient 1645-nm Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Young, York E.; Setzler, Scott D.; Snell, Kevin J.; Budni, Peter A.; Pollak, Thomas M.; Chicklis, E. P.

    2004-05-01

    We report a resonantly fiber-laser-pumped Er:YAG laser operating at the eye-safe wavelength of 1645 nm, exhibiting 43% optical efficiency and 54% incident slope efficiency and emitting 7-W average power when repetitively Q switched at 10 kHz. To our knowledge, this is the best performance (conversion efficiency and average power) obtained from a bulk solid-state Q-switched erbium laser. At a 1.1-kHz pulse repetition frequency the laser produces 3.4-mJ pulses with a corresponding peak power of 162 kW. Frequency doubling to produce 822.5-nm, 4.7-kW pulses at 10 kHz was performed to demonstrate the laser's utility.

  8. Cs 728 nm Laser Spectroscopy and Faraday Atomic Filter

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Zheng; Tao, Zhi-Ming; Jiang, Zhao-Jie; Chen, Jing-Biao

    2014-12-01

    We mainly present the 728 nm laser spectroscopy and Faraday atomic filter of Cs atoms with 650 MHz linewidth and 2.6% transmission based on an electrodeless discharge vapor lamp, compared with Rb 728 nm laser spectroscopy. Accidentally, this remarkably strong Cs 728 nm transition from the 6F7/2 state to the 5D5/2 state is only about 2.5 GHz away from the Rb 728 nm transition of the future potential four-level active optical clock, once laser cooled and trapped from the 7S1/2 state to the 5P1/2 state, as we proposed previously. A Faraday atomic filter stabilized 728 nm laser using a Cs electrodeless discharge vapor lamp with a power of 10mW will provide a frequency reference to evaluate the performance of the potential Rb four-level active optical clock at 728 nm with power less than 1 nW by 2.5 GHz heterodyne measurements.

  9. Efficient laser operation of Nd3+:Lu2O3 at various wavelengths between 917 nm and 1463 nm

    NASA Astrophysics Data System (ADS)

    von Brunn, P.; Heuer, A. M.; Fornasiero, L.; Huber, G.; Kränkel, C.

    2016-08-01

    Even though the first Nd3+-doped sesquioxide lasers have been realized more than 50 years ago, up to now no reports on efficient laser operation of Nd3+:doped sesquioxides can be found. In this work, we review the favorable spectroscopic properties of the sesquioxide Nd3+:Lu2O3 in terms of ground state absorption, stimulated emission, and excited state absorption cross sections as well as the upper level lifetime. Making use of these properties, we achieved efficient laser performance on eight different laser transitions in the wavelength range between 917 nm and 1463 nm under Ti:sapphire laser pumping using state-of-the-art HEM-grown Nd3+:Lu2O3 crystals with good optical quality. At the strongest transition around 1076 nm we determined a slope efficiency of 69%, which represents the highest efficiency ever obtained for a Nd3+-doped sesquioxide. Furthermore, we could generate watt level output powers and high slope efficiencies for seven other transitions. Lasers at 917 nm, 1053 nm, 1108 nm and 1463 nm were realized for the first time and the latter represents one of the longest laser wavelengths obtained on the 4F3/2  →  4I13/2 transition in Nd3+-doped materials.

  10. Detection of chloride in reinforced concrete using a dualpulsed laser-induced breakdown spectrometer system: comparative study of the atomic transition lines of Cl I at 594.85 and 837.59 nm.

    PubMed

    Gondal, Mohammed Ashraf; Dastageer, Mohamed Abdulkader; Maslehuddin, Mohammed; Alnehmi, Abdul Jabar; Al-Amoudi, Omar Saeed Baghabra

    2011-07-10

    The presence of chloride in reinforced concrete can cause severe damage to the strength and durability of buildings and bridges. The detection of chloride in concrete structures at early stages of the corrosion buildup process is, therefore, very important. However, detection of chlorine in trace amounts in concrete is not a simple matter. A dual-pulsed laser-induced breakdown spectrometer (LIBS) has been developed at our laboratory for the detection of chloride contents in reinforced concrete by using two atomic transition lines of neutral chlorine (Cl I) at 594.8 and 837.5 nm. A calibration curve was also established by using standard samples containing chloride in known concentration in the concrete. Our dual-pulsed LIBS system demonstrated a substantial improvement in the signal level at both wavelengths (594.8 and 837.5 nm). However, the new atomic transition line at 594.8 nm shows a significant improvement compared to the line at 837.5 nm in spite of the fact that the relative intensity of the former is 0.1% of the latter. This weak signal level of the 837.5 nm transition line of chlorine can be attributed to some kind of self-absorption process taking place in the case of the concrete sample.

  11. Treatment of telangiectasias with the 532-nm and the 532/940-nm diode laser.

    PubMed

    Carniol, Paul J; Price, Jonathan; Olive, Alisa

    2005-05-01

    Recently, a dual-wavelength 532/940-nm laser has become available for treatment of facial vascular lesions as an alternative to the flashlamp pumped-dye lasers. Most facial vascular lesions will respond to the 532-nm wavelength. However, some of the larger and deeper lesions are resistant to this laser. The 940-nm wavelength can be used to treat these resistant lesions. Sixteen patients with 532-nm laser-resistant vascular lesions were treated with the 940-nm laser. Fourteen of these 16 patients had improvement in their telangiectasia in response to these treatments. Most facial l telangiectasias respond well to treatment with the 532-nm laser. However, some of the larger and deeper lesions will not respond well to this laser. The 940-nm wavelength laser can be used to treat these 532-nm laser resistant lesions.

  12. Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm

    NASA Astrophysics Data System (ADS)

    Gondal, M. A.; Maganda, Y. W.; Dastageer, M. A.; Al Adel, F. F.; Naqvi, A. A.; Qahtan, T. F.

    2014-04-01

    Fourth harmonic of a pulsed Nd:YAG laser (wavelength 266 nm) in combination with high resolution spectrograph equipped with Gated ICCD camera has been employed to design a high sensitive analytical system. This detection system is based on Laser Induced Breakdown Spectroscopy and has been tested first time for analysis of semi-fluid samples to detect fluoride content present in the commercially available toothpaste samples. The experimental parameters were optimized to achieve an optically thin and in local thermo dynamic equilibrium plasma. This improved the limits of detection of fluoride present in tooth paste samples. The strong atomic transition line of fluorine at 731.102 nm was used as the marker line to quantify the fluoride concentration levels. Our LIBS system was able to detect fluoride concentration levels in the range of 1300-1750 ppm with a detection limit of 156 ppm.

  13. 308-nm excimer laser in endodontics

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  14. Laser etching of quartz and teflon with 157 nm and 193 nm laser radiation

    NASA Astrophysics Data System (ADS)

    Herman, Peter R.; Chen, Boyi; Moore, J. David

    1993-10-01

    Laser etching rates are presented for Teflon and quartz at 193 nm and 157 nm wavelengths. The shorter 157 nm wavelength yields high-quality surfaces with etching thresholds at low fluences of 57 and 470 mJ/cm2, respectively, affording features well-suited to micromachining applications in the electronics and photonics industries. At 193 nm, etching profiles are severely degraded. A computer model was developed to model the ablation, swelling, incubation, and plume absorption processes observed in Teflon under 193 nm irradiation. The computer results satisfactorily represent the experimental data over a large fluence range of 0.6 to 13 J/cm2 with four adjustable parameters.

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

    NASA Astrophysics Data System (ADS)

    Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

    2016-07-01

    We report the preparation of narrow-linewidth 637.2 nm laser device by single-pass sum-frequency generation (SFG) of two infrared lasers at 1560.5 nm and 1076.9 nm in PPMgO:LN crystal. Over 8.75 W of single-frequency continuously tunable 637.2 nm laser is realized, and corresponding optical-optical conversion efficiency is 38.0%. We study the behavior of crystals with different poling periods. The detailed experiments show that the output red lasers have very good power stability and beam quality. This high-performance 637.2 nm laser is significant for the realization of high power ultra-violet (UV) 318.6 nm laser via cavity-enhanced frequency doubling. Narrow-linewidth 318.6 nm laser is important for Rydberg excitation of cesium atoms via single-photon transition.

  16. 395-nm and 790-nm femtosecond laser ablation of aluminum-doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Higashikawa, Kouji; Hanabusa, Mitsugu

    2000-11-01

    We used 395-nm and 790-nm femtosecond laser pulses to deposit aluminum-doped zinc oxide films by pulsed laser deposition. Electrical resistivity of the films was lowered (5.6 x 104(Omega) cm) at 200 degree(s)C for the 395-nm laser pulses, while maintaining the optical transparency. In addition, the deposition rate increased six times. Optical emission was measured to compare the plumes generated by 395-nm and 790-nm laser pulses. We found that the emission from ions was suppressed relative to neutral atoms. Also the kinetic energy of ejected species was nearly doubled for the 395-nm laser pulses.

  17. 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.

  18. Endovenous laser ablation of the great saphenous vein comparing 1920-nm and 1470-nm diode laser.

    PubMed

    Mendes-Pinto, Daniel; Bastianetto, Paulo; Cavalcanti Braga Lyra, Lívia; Kikuchi, Rodrigo; Kabnick, Lowell

    2016-12-01

    The aim of this study was to compare venous occlusion rates at a one-year follow-up comparing 1920-nm versus 1470-nm endolaser. Randomized prospective study with consecutive patients with varicose veins associated to great saphenous reflux. The 1470-nm laser ablation was performed in continuous mode, with power of 10 W, while for the 1920-nm it was set in 5 W. Follow-up data were collected at the 7-day, 30-day, 3-month, 6-month and 1-year visits, and involved clinical, ultrasound evaluation and measurement of occlusion length. Sixty seven patients were included, with 42 limbs operated in the 1470-nm group and 48 limbs in the 1920-nm group. There were no differences in relation to age, CEAP (Clinical, Etiologic, Anatomical and Pathological Classification), VCSS (Venous Clinical Severity Score) and saphenous diameter. The resulting LEED in 1920-nm group was 17.8±0.6 J/cm and vs. 24.7±0.8 J/cm in 1470-nm group (P<0.01). Closure rates were lower for the 1920-nm group: 90.9% vs. 96.8% (P=0.06) at 30 days, 87.5% vs. 96.3% at 6 months (P=0.03), and 87.5% vs. 94.7% (P=0.05) at one year. The 1920-nm group had less ecchymosis (18.7% vs. 52.4%), induration (12.4% vs. 38.1%) and days of analgesic use (1.4±0.2 vs. 2.4±0.4). CEAP and VCSS were reduced over time in both groups. Treatment with endolaser 1920-nm was feasible and with reduced complications. The use of low endoluminal energy resulted in lower vein occlusion rates comparing to the 1470-nn laser. Clinical outcome scores were similar between groups.

  19. Corneal and skin laser exposures from 1540-nm laser pulses

    NASA Astrophysics Data System (ADS)

    Johnson, Thomas E.; Mitchell, Michael A.; Rico, Pedro J.; Fletcher, David J.; Eurell, Thomas E.; Roach, William P.

    2000-06-01

    Mechanisms of tissue damage are investigated for skin and cornea exposures from 1540 nm ('eye safe') laser single pulses of 0.8 milli-seconds. New skin model data point out the advantages of using the Yucatan mini-pig versus the Yorkshire pig for in-vivo skin laser exposures. Major advantages found include similarities in thickness and melanin content when compared with human skin. Histology from Yucatan mini-pig skin exposures and the calculation of an initial ED50 threshold indicate that the main photon tissue interaction may not be solely due to water absorption. In-vitro corneal equivalents compared well with in-vivo rabbit cornea exposure under similar laser conditions. In-vivo and in-vitro histology show that initial energy deposition leading to damage occurs intrastromally, while epithelial cells show no direct injury due to laser light absorption.

  20. Room-temperature, continuous-wave, 946-nm Nd:YAG laser pumped by laser-diode arrays and intracavity frequency doubling to 473 nm

    SciTech Connect

    Risk, W.P.; Lenth, W.

    1987-12-01

    We report the use of GaAlAs laser-diode arrays to pump a cw Nd:YAG laser operating on the 946-nm /sup 4/F/sub 3/2/..-->../sup 4/I/sub 9/2/ transition. At room temperature, the lasing threshold was reached with 58 mW of absorbed pump power, and, with 175 mW of absorbed pump power, 42 mW of output power at 946 nm was obtained in a TEM/sub 00/ mode by using 0.7% output coupling. In addition, pumping with an infrared dye laser operating in a pure TEM/sub 00/ mode was used to investigate the effects of reabsorption loss that are characteristic of the 946-nm laser transition. LiIO/sub 3/ was used as an intracavity doubling crystal, and 100 ..mu..W of blue light was generated by using diode-laser pumping in a nonoptimized cavity.

  1. 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.

  2. 420nm alkali blue laser based on two-photon absorption

    NASA Astrophysics Data System (ADS)

    Tan, Yan-nan; Li, Yi-min; Liu, Tong; Gong, Fa-quan; Jia, Chun-yan; Hu, Shu; Gai, Bao-dong; Guo, Jing-wei; Liu, Wan-fa

    2015-02-01

    Based on two-photon absorption, a 420nm blue laser of alkali Rb vapor was demonstrated, and a dye laser was used as the pumping laser. Utilizing the energy level structure of Rb atom, lasering mechanism and two-photon absorption process are analyzed. Absorbing two 778.1nm photons, Rb atoms were excited from 52 S1/2 to 52 D5/2, then relaxed to 62 P3/2 with mid infrared photon radiation. 420nm blue laser was achieved by the transition 62 P3/2-->52 S1/2. To improve efficiency of the blue laser, two-photon resonant excitation pumped alkali vapor blue lasers are proposed, which will be good beam quality, high efficiency and scalable blue lasers. The development of diode pumped alkali vapor blue laser is expected.

  3. Laser Damage Growth in Fused Silica with Simultaneous 351 nm and 1053 nm irradiation

    SciTech Connect

    Norton, M A; Carr, A V; Carr, C W; Donohue, E E; Feit, M D; Hollingsworth, W G; Liao, Z; Negres, R A; Rubenchik, A M; Wegner, P J

    2008-10-24

    Laser-induced growth of optical damage often determines the useful lifetime of an optic in a high power laser system. We have extended our previous work on growth of laser damage in fused silica with simultaneous 351 nm and 1053 nm laser irradiation by measuring the threshold for growth with various ratios of 351 nm and 1053 nm fluence. Previously we reported that when growth occurs, the growth rate is determined by the total fluence. We now find that the threshold for growth is dependent on both the magnitude of the 351 nm fluence as well as the ratio of the 351 nm fluence to the 1053 nm fluence. Furthermore, the data suggests that under certain conditions the 1053 nm fluence does not contribute to the growth.

  4. Ultraviolet 320 nm laser excitation for flow cytometry.

    PubMed

    Telford, William; Stickland, Lynn; Koschorreck, Marco

    2017-02-27

    Although multiple lasers and high-dimensional analysis capability are now standard on advanced flow cytometers, ultraviolet (UV) lasers (usually 325-365 nm) remain an uncommon excitation source for cytometry. This is primarily due to their cost, and the small number of applications that require this wavelength. The development of the Brilliant Ultraviolet (BUV fluorochromes, however, has increased the importance of this formerly niche excitation wavelength. Historically, UV excitation was usually provided by water-cooled argon- and krypton-ion lasers. Modern flow cytometers primary rely on diode pumped solid state lasers emitting at 355 nm. While useful for all UV-excited applications, DPSS UV lasers are still large by modern solid state laser standards, and remain very expensive. Smaller and cheaper near UV laser diodes (NUVLDs) emitting at 375 nm make adequate substitutes for 355 nm sources in many situations, but do not work as well with very short wavelength probes like the fluorescent calcium chelator indo-1. In this study, we evaluate a newly available UV 320 nm laser for flow cytometry. While shorter in wavelength that conventional UV lasers, 320 is close to the 325 nm helium-cadmium wavelength used in the past on early benchtop cytometers. A UV 320 nm laser was found to excite almost all Brilliant Ultraviolet dyes to nearly the same level as 355 nm sources. Both 320 nm and 355 nm sources worked equally well for Hoechst and DyeCycle Violet side population analysis of stem cells in mouse hematopoetic tissue. The shorter wavelength UV source also showed excellent excitation of indo-1, a probe that is not compatible with NUVLD 375 nm sources. In summary, a 320 nm laser module made a suitable substitute for conventional 355 nm sources. This laser technology is available in a smaller form factor than current 355 nm units, making it useful for small cytometers with space constraints. © 2017 International Society for Advancement of Cytometry.

  5. High-Performance 1645-nm Er: YAG Laser

    DTIC Science & Technology

    2007-09-25

    laser set-up is shown in Figure 1. An IPG Photonics TEM00 erbium fiber laser , which provided 20 W cw power at 1532.4 nm, was used in these experi...output of the resonantly fiber - laser -pumped Er:AYG laser at 1645 nm using 0.25% doped crystal out- performed the 0.5% doped crystal. In addition to the...the advantages of small quantum defect and small thermal load for the laser materials. High-brightness erbium fiber pump lasers at 1532 nm not only

  6. Visible laser operation of Pr3+-doped fluoride crystals pumped by a 469 nm blue laser.

    PubMed

    Xu, Bin; Camy, Patrice; Doualan, Jean-Louis; Cai, Zhiping; Moncorgé, Richard

    2011-01-17

    We report continuous-wave (CW) laser operation of Pr3+-doped LiLuY4, LiYF4 and KY3F10 single crystals in the Red, Orange and Green spectral regions by using a new pumping scheme. The pump source is an especially developed compact, slightly tunable and intracavity frequency-doubled diode-pumped Nd:YAG laser delivering a CW output power of 0.9W at 469.12 nm. At this pump wavelength, efficient room temperature laser emissions corresponding to the 3P0→3F2, 3P0→3H6 and 3P1→3H5 Pr3+ transitions are observed. While a maximum slope efficiency of 45% is obtained in the red with Pr:LiYF4, the demonstration is made for the first time of the orange laser operation of Pr:KY3F10 at about 610 nm.

  7. Picosecond holmium fibre laser pumped at 1125 \\ {\\text{nm}}

    NASA Astrophysics Data System (ADS)

    Kamynin, V. A.; Filatova, S. A.; Zhluktova, I. V.; Tsvetkov, V. B.

    2016-12-01

    We report a passively mode-locked, all-fibre holmium laser based on nonlinear polarisation rotation. As a pump source use is made of an 1125-{\\text{nm}} ytterbium-doped fibre laser. The pulse repetition rate of the holmium laser is 7.5 {\\text{MHz}}, and the pulse duration does not exceed 52 {\\text{ps}} at wavelengths of 2065 and 2080 {\\text{nm}}. The average laser output power reaches 5 {\\text{mW}}.

  8. End-Pumped 895 nm Cs Laser

    SciTech Connect

    Beach, R J; Krupke, W F; Kanz, V K; Payne, S A; Dubinskii, M A; Merkle, L D

    2004-02-09

    A scientific demonstration of a Cs laser is described in which the measured slope efficiency is as high as 0.59 W/W using a Ti:Sapphire laser as a surrogate diode-pump. In addition to presenting experimental data, a laser energetics model that accurately predicts laser performance is described and used to model a power-scaled, diode-pumped system.

  9. Rb-stabilized laser at 1572 nm for CO2 monitoring

    NASA Astrophysics Data System (ADS)

    Matthey, R.; Moreno, W.; Gruet, F.; Brochard, P.; Schilt, S.; Mileti, G.

    2016-06-01

    We have developed a compact rubidium-stabilized laser system to serve as optical frequency reference in the 1.55-μm wavelength region, in particular for CO2 monitoring at 1572 nm. The light of a fiber-pigtailed distributed feedback (DFB) laser emitting at 1560 nm is frequency-doubled and locked to a sub-Doppler rubidium transition at 780 nm using a 2-cm long vapor glass cell. Part of the DFB laser light is modulated with an electro-optical modulator enclosed in a Fabry-Perot cavity, generating an optical frequency comb with spectral coverage extending from 1540 nm to 1580 nm. A second slave DFB laser emitting at 1572 nm and offset-locked to one line of the frequency comb shows a relative frequency stability of 1.10-11 at 1 s averaging time and <4.10-12 from 1 hour up to 3 days.

  10. LASERS: Study of a Tm:Ho:YLF laser pumped by a Raman shifted erbium-doped fibre laser at 1678 nm

    NASA Astrophysics Data System (ADS)

    Kalachev, Yu L.; Mikhailov, Viktor A.; Podreshetnikov, V. V.; Shcherbakov, Ivan A.

    2010-06-01

    The lasing, spectral, and luminescent characteristics of a Tm:Ho:YLF laser pumped by a Raman shifted erbium-doped fibre laser (λ = 1678 nm) into the 1682-nm absorption line of the 3H6-3F4 transition of the Tm3+ ion are studied. It is shown that the total (with respect to the absorbed power) and slope laser efficiencies upon pulsed pumping reach 46% and 50%, respectively. The output radiation power in the cw regime is 400 mW. The comparative measurements showed that pumping by a fibre laser at 1678 nm is more efficient than diode pumping at 792 nm.

  11. Development of high coherence high power 193nm laser

    NASA Astrophysics Data System (ADS)

    Tanaka, Satoshi; Arakawa, Masaki; Fuchimukai, Atsushi; Sasaki, Yoichi; Onose, Takashi; Kamba, Yasuhiro; Igarashi, Hironori; Qu, Chen; Tamiya, Mitsuru; Oizumi, Hiroaki; Ito, Shinji; Kakizaki, Koji; Xuan, Hongwen; Zhao, Zhigang; Kobayashi, Yohei; Mizoguchi, Hakaru

    2016-03-01

    We have been developing a hybrid 193 nm ArF laser system that consists of a solid state seeding laser and an ArF excimer laser amplifier for power-boosting. The solid state laser consists of an Yb-fiber-solid hybrid laser system and an Er-fiber laser system as fundamentals, and one LBO and three CLBO crystals for frequency conversion. In an ArF power amplifier, the seed laser passes through the ArF gain media three times, and an average power of 110 W is obtained. As a demonstration of the potential applications of the laser, an interference exposure test is performed.

  12. Orthogonally polarized dual-wavelength Nd:LuVO4 laser at 1086 nm and 1089 nm.

    PubMed

    Huang, Y P; Cho, C Y; Huang, Y J; Chen, Y F

    2012-02-27

    A comparison between the fluorescence spectra of the Nd-doped vanadate crystals (Nd:YVO4, Nd:GdVO4, Nd:LuVO4) for the 4F3/2 → 4I11/2 transition is studied. We numerically analyze the condition of gain-to-loss balance via an uncoated intracavity etalon to achieve the dual-wavelength operation. We further experimentally demonstrate the orthogonally polarized dual-wavelength laser with a single Nd:LuVO4 crystal. The simultaneous dual-wavelength Nd:LuVO4 laser at 1085.7 nm in σ polarization and 1088.5 nm in π polarization is realized. At an incident pump power of 12 W, the average output power obtained at 1085.7 nm and 1088.5 nm is 0.4 W and 1.7 W, respectively.

  13. Studies on nanosecond 532nm and 355nm and ultrafast 515nm and 532nm laser cutting super-hard materials

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

    2017-02-01

    In this paper, micro-processing of three kinds of super-hard materials of poly-crystal diamond (PCD)/tungsten-carbide (WC), CVD-diamond and cubic boron nitride (CNB) has been systematically studied using nanosecond laser (532nm and 355nm), and ultrafast laser (532nm and 515nm). Our purpose is to investigate a full laser micro-cutting solution to achieve a ready-to-use cutting tool insert (CTI). The results show a clean cut with little burns and recasting at edge. The cutting speed of 2-10mm/min depending on thickness was obtained. The laser ablation process was also studied by varying laser parameters (wavelength, pulse width, pulse energy, repetition rate) and tool path to improve cutting speed. Also, studies on material removal efficiency (MRE) of PCD/WC with 355nm-ns and 515nm-fs laser as a function of laser fluence show that 355nm-ns laser is able to achieve higher MRE for PCD and WC. Thus, ultrafast laser is not necessarily used for superhard material cutting. Instead, post-polishing with ultrafast laser can be used to clean cutting surface and improve smoothness.

  14. 11 W narrow linewidth laser source at 780nm for laser cooling and manipulation of Rubidium

    NASA Astrophysics Data System (ADS)

    Sané, S. S.; Bennetts, S.; Debs, J. E.; Kuhn, C. C. N.; McDonald, G. D.; Altin, P. A.; Close, J. D.; Robins, N. P.

    2012-04-01

    We present a narrow linewidth continuous laser source with over 11 Watts of output power at 780nm, based on single-pass frequency doubling of an amplified 1560nm fibre laser with 36% efficiency. This source offers a combination of high power, simplicity, mode quality and stability. Without any active stabilization, the linewidth is measured to be below 10kHz. The fibre seed is tunable over 60GHz, which allows access to the D2 transitions in 87Rb and 85Rb, providing a viable high-power source for laser cooling as well as for large-momentum-transfer beamsplitters in atom interferometry. Sources of this type will pave the way for a new generation of high flux, high duty-cycle degenerate quantum gas experiments.

  15. 11 W narrow linewidth laser source at 780 nm for laser cooling and manipulation of Rubidium.

    PubMed

    Sané, S S; Bennetts, S; Debs, J E; Kuhn, C C N; McDonald, G D; Altin, P A; Close, J D; Robins, N P

    2012-04-09

    We present a narrow linewidth continuous laser source with over 11 W output power at 780 nm, based on single-pass frequency doubling of an amplified 1560 nm fibre laser with 36% efficiency. This source offers a combination of high power, simplicity, mode quality and stability. Without any active stabilization, the linewidth is measured to be below 10 kHz. The fibre seed is tunable over 60 GHz, which allows access to the D₂ transitions in ⁸⁷Rb and ⁸⁵Rb, providing a viable high-power source for laser cooling as well as for large-momentum-transfer beamsplitters in atom interferometry. Sources of this type will pave the way for a new generation of high flux, high duty-cycle degenerate quantum gas experiments.

  16. Comparison of 980-nm and 1070-nm in endovenous laser treatment (EVLT)

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Tabakoglu, Ozgur; Ergenoglu, Mehmet U.; Gülsoy, Murat

    2009-07-01

    The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

  17. Modeling of Tm-doped ZBLAN blue upconversion fiber lasers operating at 455 nm

    NASA Astrophysics Data System (ADS)

    Brunet, Francois; Laperle, Pierre; Vallee, Real; LaRochelle, Sophie; Pujol, Lionel

    1999-12-01

    We present a model for 455-nm thulium-doped fluorozirconate fiber lasers co-pumped at 645 nm and 1064 nm. Twelve radiative transitions are accounted for in our model, along with cross- relaxation and cooperative upconversion processes. Blue laser output power is computed using a rate equation analysis. Relevant spectroscopic data used in our model are given, including cross-section measurements that we have performed. The results of our simulation show a good agreement with previously published experimental data. The importance of cross-relaxation processes is discussed. The dependence of output laser power on fiber length, output mirror reflectivity, and pump powers is also addressed.

  18. Simultaneous three-wavelength continuous wave laser at 946 nm, 1319 nm and 1064 nm in Nd:YAG

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Zhao, Lianshui; Zhai, Pei; Xia, Jing; Fu, Xihong; Li, Shutao

    2013-01-01

    A continuous-wave (cw) diode-end-pumped Nd:YAG laser that generates simultaneous laser at the wavelengths 946 nm, 1319 nm and 1064 nm is demonstrated. The optimum oscillation condition for the simultaneous three-wavelength operation has been derived. Using the separation of the three output couplers, we obtained the maximum output powers of 0.24 W at 946 nm, 1.07 W at 1319 nm and 1.88 W at 1064 nm at the absorbed pump power of 11.2 W. A total output power of 3.19 W for the three-wavelength was achieved at the absorbed pump power of 11.2 W with optical conversion efficiency of 28.5%.

  19. Atomic frequency reference at 1033 nm for ytterbium (Yb)-doped fiber lasers and applications exploiting a rubidium (Rb) 5S1/2 to 4D5/2 one-colour two-photon transition.

    PubMed

    Roy, Ritayan; Condylis, Paul C; Johnathan, Yik Jinen; Hessmo, Björn

    2017-04-03

    We demonstrate a two-photon transition of rubidium (Rb) atoms from the ground state (5S1/2) to the excited state (4D5/2), using a home-built ytterbium (Yb)-doped fiber amplifier at 1033 nm. This is the first demonstration of an atomic frequency reference at 1033 nm as well as of a one-colour two-photon transition for the above energy levels. A simple optical setup is presented for the two-photon transition fluorescence spectroscopy, which is useful for frequency stabilization for a broad class of lasers. This spectroscopy has potential applications in the fiber laser industry as a frequency reference, particularly for the Yb-doped fiber lasers. This two-photon transition also has applications in atomic physics as a background- free high- resolution atom detection and for quantum communication, which is outlined in this article.

  20. High power room temperature 1014.8 nm Yb fiber amplifier and frequency quadrupling to 253.7 nm for laser cooling of mercury atoms.

    PubMed

    Hu, Jinmeng; Zhang, Lei; Liu, Hongli; Liu, Kangkang; Xu, Zhen; Feng, Yan

    2013-12-16

    An 8 W continuous wave linearly-polarized single-frequency 1014.8 nm fiber amplifier working at room temperature is developed with commercial double-clad single-mode Yb-doped silica fiber. Re-absorption at the laser wavelength and amplified spontaneous emission at longer wavelength are managed by optimizing the amplifier design. The laser has a linewidth of ~24 kHz without noticeable broadening after amplification. Using two resonant cavity frequency doublers, 1.03 W laser at 507.4 nm and 75 mW laser at 253.7 nm are generated with 4 W 1014.8 nm laser. Both absorption and saturated absorption spectra of the (1)S(0) - (3)P(1) transition of atomic mercury are measured with the 253.7 nm laser.

  1. Red laser-diode pumped 806 nm Tm3+: ZBLAN fibre laser

    NASA Astrophysics Data System (ADS)

    Juárez-Hernández, M.; Mejía, E. B.

    2017-06-01

    A Tm3+-doped fluorozirconate (ZBLAN) fibre laser operating CW at 806 nm when diode-pumped at 687 nm is described for the first time. This device is based on the 3F4  →  3H6 transition, and is suitable for first telecom window and sensing applications. A slope efficiency of 50.3% and low threshold pump-power of 11.6 mW were obtained. Maximum output power of 15 mW for 40 mW coupled pump was achieved.

  2. Continuous 1052, 1064 nm dual-wavelength Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Wang, Xiaozhong; Yuan, Haiyang; Wang, Mingshan; Huang, Wencai

    2016-10-01

    Dual-wavelength lasers are usually obtained through balancing the net gain of the two oscillating lines. Competition between transitions 1052 nm, 1061 nm and 1064 nm is utilized to realize a continuous wave 1052 and 1064 nm dual-wavelength Nd:YAG laser firstly in this paper. A specially designed Fabry-Perot band-pass filter is exploited as output coupler to control the thresholds of the oscillating wavelengths. The maximum power of the dual-wavelength laser is 1.6 W and the slope efficiency is about 10%. The power instability of the output dual-wavelength laser is smaller than ±4% in half an hour. The mechanism presented in this paper may provide a new way to obtain dual-wavelength lasers.

  3. 40nm tunable multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Qingsong; Wang, Tianshu; Zhang, Peng; Dong, Keyan; Jiang, Huilin

    2014-12-01

    A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier (EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

  4. Applications of the 308-nm excimer laser in dermatology

    NASA Astrophysics Data System (ADS)

    Farkas, A.; Kemeny, L.

    2006-05-01

    Excimer lasers contain a mixture of a noble inert gas and a halogen, which form excited dimers only in the activated state. High-energy current is used to produce these dimers, which have a very short lifetime, and after their fast dissociation they release the excitation energy through ultraviolet photons. The application of these lasers proved to be successful in medicine, including the field of ophthalmology, cardiology, angiology, dentistry, orthopaedics, and, in recent years, dermatology. For medical purposes, the 193-nm argon fluoride, the 248-nm krypton fluoride, the 351-nm xenon fluoride, and the 308-nm xenon chloride lasers are used. Recently, the 308-nm xenon chloride laser has gained much attention as a very effective treatment modality in dermatological disorders. It was successfully utilized in psoriasis; later, it proved to be useful in handling other lightsensitive skin disorders and even in the treatment of allergic rhinitis. This review summarizes the possible applications of this promising tool in dermatology.

  5. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  6. Damage Thresholds for Cultures RPE Cells Exposed to Lasers at 532 nm and 458 nm

    DTIC Science & Technology

    2007-06-01

    in onhuman primate studies. Results of in vivo studies have hown that laser damage in the retina depends upon wave- ength, power level, and duration...laser exposure similarly to RPE cells in nonhuman primate models. Our approach was to determine threshold ED50 radiant exposures for damage over a broad...our n vitro system 160 MP/cell responds in a fundamentally imilar fashion to 532-nm laser irradiation, as does the non- uman primate retina

  7. Retinal Injury From Simultaneous Exposure to 532 nm and 860 nm Laser Irradiation

    DTIC Science & Technology

    2004-01-01

    860 nm Laser Irradiation DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report: TITLE: Laser...Radiation Branch, Brooks City-Base, TX 78235-52783U.S Army Medical Research Detachment , Walter Reed Army Institute of Research, Brooks AFB, Texas 78235...This study was designed to investigate the retinal effects of two lasers being used to simultaneously expose the retina and determine the minimum

  8. Laser-induced bulk damage of silica glass at 355nm and 266nm

    NASA Astrophysics Data System (ADS)

    Kashiwagi, R.; Aramomi, S.

    2016-12-01

    Laser processing machines using Nd:YAG 3rd harmonic wave (355 nm) and 4th harmonic wave (266 nm) have been developed and put into practical use lately. Due to this, optical elements with high laser durability to 355 nm and 266 nm are required. Silica glass is the optical element which has high UV transmission and high laser durability. Laser-induced surface damage of the silica glass has been studied in detail, but we hardly have the significant knowledge of laserinduced bulk damage. This knowledge is required in order to evaluate the silica glass itself. That is because cracks and scratches on the surface give rise to a higher possibility of damage. Therefore, we studied the laser durability of a variety of the silica glass samples by 1-on-1 and S-on-1 laser-induced bulk damage threshold (LIDT) at 355 nm and 266 nm. In this study, we gained knowledge in three areas about bulk damage to the silica glass. First, the LIDT became lower as shot counts increased. Second, the LIDT decreased as the hydroxyl content in the silica glass increased. Last, the LIDT became higher as the hydrogen concentration in the silica glass increased. Under the UV irradiation, impurities are generated and the silica glass absorbs more light. Therefore, the LIDT decreased as shot counts increased. Also, the hydroxyl in particular generates more impurities, so damage easily occurs. On the other hand, the hydrogen reacts with impurities and absorption is suppressed. Based on these results, we can improve laser durability at 355 nm and 266 nm by reducing the hydroxyl content and increasing the hydrogen concentration in the silica glass.

  9. Spatial coherence of low-cost 532nm green lasers

    NASA Astrophysics Data System (ADS)

    Astadjov, Dimo N.; Prakash, Om

    2013-03-01

    We report for first time, to our best knowledge, experimental measurement of the degree of spatial coherence of a λ532 nm laser source (of a DPSS type - frequency doubled Nd:YVO4 laser) by reversal shear interferometers developed in our laboratories not so long. The degree of a full-sized non-apertured laser beam turned out to be quite high viz. up to 0.6 which is comparable with the degree of spatial coherence of λ510 nm copper lasers we had measured repeatedly for last decade.

  10. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  11. Experimental study of 248nm excimer laser etching of alumina

    NASA Astrophysics Data System (ADS)

    Hu, Hongtao; Shao, Jingzhen; Wang, Xi; Fang, Xiaodong

    2016-10-01

    The 248 nm excimer laser etching characteristic of alumina ceramic and sapphire had been studied using different laser fluence and different number of pulses. And the interaction mechanism of 248 nm excimer laser with alumina ceramic and sapphire had been analyzed. The results showed that when the laser fluence was less than 8 J/cm2, the etching depth of alumina ceramic and sapphire were increased with the increase of laser fluence and number of pulses. At the high number pulses and high-energy, the surface of the sapphire had no obvious melting phenomenon, and the alumina ceramic appeared obvious melting phenomenon. The interaction mechanism of excimer laser with alumina ceramics and sapphire was mainly two-photon absorption. But because of the existence of impurities and defects, the coupling between the laser radiation and ceramic and sapphire was strong, and the thermal evaporation mechanism was also obvious.

  12. Effects of 946-nm thermal shift and broadening on Nd3+:YAG laser performance

    NASA Astrophysics Data System (ADS)

    Seyed Ebrahim, Pourmand; Ghasem, Rezaei

    2015-12-01

    Spectroscopic properties of flashlamp pumped Nd3+:YAG laser are studied as a function of temperature in a range from -30 °C to 60 °C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4F3/2 → 4I9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state. Project supported by Estahban Branch, Islamic Azad University.

  13. Endobronchial therapy with a thulium fiber laser (1940 nm).

    PubMed

    Gesierich, Wolfgang; Reichenberger, Frank; Fertl, Andreas; Haeussinger, Karl; Sroka, Ronald

    2014-06-01

    Nd:YAG laser (1064 nm) is standard in bronchology. The thulium fiber laser (1940 nm) has a nearly 1000-fold increased absorption in water, enabling precise tissue ablation with a small margin of coagulation, whereas 1064-nm laser light penetrates deeper into tissue with less controllable effects. To assess the safety, feasibility, and versatility of endobronchial thulium laser therapy in an observational cohort study. Endobronchial treatment with the thulium fiber laser was performed in a cohort study of 187 bronchoscopies on 132 consecutive patients with 135 endobronchial lesions amenable to laser resection. The thulium fiber laser produced superficial, precise, and rapid tissue ablation. Eighty-one lesions were completely vaporized; 82 lesions were treated by deep tissue destruction by inserting the fiber into tissue followed by mechanical resection. Tumor bleeding was coagulated with rapid and sustained hemostasis (n = 28). Nitinol stents were removed after resection of severe granulation tissue overgrowth (n = 10). Intact stents were maintained after ablation of in-stent tissue (n = 47). In 11 cases, bleeding occurred during laser treatment (n = 11 of 187). Power settings between 5 and 20 W were found to be safe. Endobronchial therapy with the thulium laser at 1940 nm seems to be safe, feasible, and highly versatile for treatment of airway stenosis and stent obstruction caused by tissue ingrowth. Further studies are warranted. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  14. Narrow linewidth Yb-doped fiber laser at 1120 nm.

    PubMed

    Xiaojuan, Liu; Shenggui, Fu; Liping, Guo; Kezhen, Han

    2013-03-20

    A 974 nm laser diode pumped 1120 nm ytterbium (Yb)-doped fiber laser with all fiber components has been experimentally demonstrated. The resonator is composed of a normal single-mode Yb-doped fiber 1 m long and a pair of fiber Bragg gratings. Up to 21.6 mW of continuous-wave output power is generated when the launched pump power is 161 mW with an optical-to-optical conversion efficiency of 13.4%. The central wavelength is 1120.89 nm with a linewidth as narrow as 0.02 nm. Additionally, a similar fiber laser with a 2 m long gain medium displays a broadened linewidth. The results of the two fiber lasers are compared and discussed in the paper.

  15. Injection locking of a diode-pumped Nd:YAG laser at 946 nm

    SciTech Connect

    Hollemann, G.; Peik, E.; Rusch, A.; Walther, H.

    1995-09-15

    Injection locking in the quasi-three-level laser system Nd:YAG {sup 4}{ital F}{sub 3/2}--{sup 4}{ital I}{sub 9/2} at 946 nm is reported. The master and slave oscillators are pumped by laser diodes. The master oscillator is frequency stabilized to a high-finesse cavity, resulting in a laser linewidth of less than 10 Hz. Using intracavity frequency doubling of the slave oscillator, we achieve a single-mode output power of 60 mW at 473 nm. The laser radiation was frequency quadrupled, resulting in an UV power of 0.55 mW at 236.5 nm. The laser system was used to excite a strongly forbidden In{sup +} transition, proposed as a new optical frequency standard. {copyright} 1995 Optical Society of America

  16. Investigations of a dual seeded 1178nm Raman laser system

    NASA Astrophysics Data System (ADS)

    Block, Matthew; Henry, Leanne J.; Klopfer, Michael; Jain, Ravinder

    2016-03-01

    The leakage of 1121 nm power from a resonator cavity because of spectral broadening seriously degrades the performance of a Raman resonator by reducing the 1121 nm circulating power and the 1178 nm output power. Therefore, it is important to understand the conditions which minimize 1121 nm power leakage, maximize 1121 intracavity and 1178 nm output power while enabling a manageable Stimulated Brillouin Scattering gain for narrow linewidth systems. It was found that cavity lengths longer than approximately 40 m didn't result in significantly more 1121 nm linewidth broadening. Relative to the high reflectivity bandwidth of the fiber Bragg gratings, it was found that 4 nm FBGs seemed to optimize 1178 nm amplification while minimizing the amount of 1121 nm power leakage. A two stage high power 1178 nm Raman system was built and 20 W of 1178 nm output power was achieved with a polarization extinction ratio of 21 and nearly diffraction limited beam quality. Linewidth broadening was found to increase as the 1178 nm output increased and was approximately 8 GHz when the 1178 nm output power was 20 W. Because of the linewidth broadening, a co-pumped second Stokes Raman laser system is not useful for the sodium guidestar laser application which requires narrow linewidth.

  17. Investigation of a Pulsed 1550 nm Fiber Laser System

    DTIC Science & Technology

    2015-12-15

    14. ABSTRACT There is a strong need for a pulsed laser system at eye safe wavelengths for illuminator applications . High power pulsed 1550 nm fiber...system at eye safe wavelengths for illuminator applications . High power pulsed 1550 nm fiber lasers systems are able to generate, shaped, pulses at...for illuminator applications . Considerations which impact the wavelength to be used are the transmissivity of the atmosphere and the responsivity of

  18. Absolute frequency measurement for the emission transitions of molecular iodine in the 982 - 985 nm range

    SciTech Connect

    Matyugin, Yu A; Ignatovich, S M; Kuznetsov, Sergei A; Nesterenko, M I; Okhapkin, M V; Pivtsov, V S; Skvortsov, Mikhail N; Bagaev, Sergei N

    2012-03-31

    We report high-precision frequency measurements of the separate hyperfine structure (HFS) components of the emission B - X system transitions of {sup 127}I{sub 2} molecules in the 982 - 985 nm range. To resolve the HFS of the emission lines, advantage was taken of the method of three-level laser spectroscopy. The function of exciting radiation was fulfilled by the second harmonic of a cw Nd : YAG laser, and the probe radiation in the 968 - 998 nm range was generated by an external-cavity diode laser. The output Nd : YAG laser frequency was locked to an HFS component of the absorption transition and the probing laser radiation to the emission transition component. When both frequencies were locked to HFS components with a common upper level, the output diode laser frequency was precisely equal to the emission transition frequency. The output frequency of the thus stabilised diode laser was measured with the help of a femtosecond optical frequency synthesiser based on a Ti : sapphire laser. We present the results of the absolute frequency measurements of 20 HFS components belonging to six vibrational - rotational transitions of the B - X system of iodine [R56(32 - 48)a1, P58(32 - 48)a1, P85(33 - 48)a1, R87(33 - 48a1, R88(33 - 48)a10] and all 15 components of the R86(33 - 48) line. The relative measurement uncertainty is equal to 7 Multiplication-Sign 10{sup -10} and is determined by the frequency instability of the diode laser radiation.

  19. Diode-pumped Nd:YAG laser emitting at 884 nm Diode-pumped Nd:YAG laser emitting at 884 nm

    NASA Astrophysics Data System (ADS)

    Chen, X.; Shao, Y.; Yuan, J. L.; Zhang, D.; Li, Y. L.

    2012-07-01

    We present what is, to the best of our knowledge, the first diode-pumped Nd-doped Y3Al5O12 (Nd:YAG) laser emitting at 884 nm, based on the 4F3/2 → 4I9/2 transition, generally used for a 946 nm emission. The use of a pump module with 16 passes through the crystal allowed the realization of a Nd:YAG thin-disk laser with 1.14 W of continuous wave (CW) output power at 884 nm. Moreover, intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 151 mW at 442 nm by using a BiB3O6 (BiBO) nonlinear crystal.

  20. A self-Q-switched all-fiber erbium laser at 1530 nm using an auxiliary 1570-nm erbium laser.

    PubMed

    Tsai, Tzong-Yow; Fang, Yen-Cheng

    2009-11-23

    We demonstrate a self-Q-switched, all-fiber, tunable, erbium laser at 1530 nm with high pulse repetition rates of 0.9-10 kHz. Through the use of an auxiliary 10-mW, 1570 nm laser that shortened the relaxation time of erbium, sequentially Q-switched pulses with pulse energies between 4 and 6 microJ and pulse widths of 40 ns were steadily achieved. A peak pulse power of 165 W was obtained.

  1. CVD-diamond external cavity Raman laser at 573 nm.

    PubMed

    Mildren, Richard P; Butler, James E; Rabeau, James R

    2008-11-10

    Recent progress in diamond growth via chemical vapor deposition (CVD) has enabled the manufacture of single crystal samples of sufficient size and quality for realizing Raman laser devices. Here we report an external cavity CVD-diamond Raman laser pumped by a Q-switched 532 nm laser. In the investigated configuration, the dominant output coupling was by reflection loss at the diamond's uncoated Brewster angle facets caused by the crystal's inherent birefringence. Output pulses of wavelength 573 nm with a combined energy of 0.3 mJ were obtained with a slope efficiency of conversion of up to 22%.

  2. 80 nm tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.

    2016-07-01

    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  3. Compact frequency-quadrupled pulsed 1030nm fiber laser

    NASA Astrophysics Data System (ADS)

    McIntosh, Chris; Goldberg, Lew; Cole, Brian; DiLazaro, Tom; Hays, Alan D.

    2016-03-01

    A compact 1030nm fiber laser for ultraviolet generation at 257.5nm is presented. The laser employs a short length of highly-doped, large core (20μm), coiled polarization-maintaining ytterbium-doped double-clad fiber pumped by a wavelength-stabilized 975nm diode. It is passively Q-switched via a Cr4+:YAG saturable absorber and generates 2.4W at 1030nm in a 110μJ pulse train. Lithium triborate (LBO) and beta-barium borate (BBO) are used to achieve 325mW average power at the fourth harmonic. The laser's small form factor, narrow linewidth and modest power consumption are suitable for use in a man-portable ultraviolet Raman explosives detection system.

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  6. Laser cooling transitions in atomic erbium.

    PubMed

    Ban, H; Jacka, M; Hanssen, J; Reader, J; McClelland, J

    2005-04-18

    We discuss laser cooling opportunities in atomic erbium, identifying five J ? J + 1 transitions from the 4f126s2 3H6 ground state that are accessible to common visible and near-infrared continuous-wave tunable lasers. We present lifetime measurements for the 4f11(4Io 15/2)5d5/26s2 (15/2, 5/2)7o state at 11888 cm-1 and the 4f11(4Io 13/2)5d3/26s2 (13/2, 5/2)7o state at 15847 cm-1, showing values of 20 +/- 4 micros and 5.6 +/- 1.4 micros, respectively. We also present a calculated value of 13 +/- 7 s-1 for the transition rate from the 4f11(4Io 15/2)5d3/26s2 (15/2, 3/2)7 o state at 7697 cm-1 to the ground state, based on scaled Hartree-Fock energy parameters. Laser cooling on these transitions in combination with a strong, fast (5.8 ns) laser cooling transition at 401 nm, suggest new opportunities for narrowband laser cooling of a large-magnetic moment atom, with possible applications in quantum information processing, high-precision atomic clocks, quantum degenerate gases, and deterministic single-atom doping of materials.

  7. 1940 nm all-fiber Q-switched fiber laser

    NASA Astrophysics Data System (ADS)

    Ahmadi, P.; Estrada, A.; Katta, N.; Lim, E.; McElroy, A.; Milner, T. E.; Mokan, V.; Underwood, M.

    2017-02-01

    We present development of a nanosecond Q-switched Tm3+-doped fiber laser with 16 W average power and 4.4 kW peak power operating at 1940 nm. The laser has a master oscillator power amplifier design, and uses large mode area Tm3+-doped fibers as the gain medium. Special techniques are used to splice Tm3+-doped fibers to minimize splice loss. The laser design is optimized to reduce non-linear effects, including modulation instability. Pulse width broadening due to high gain is observed and studied in detail. Medical surgery is a field of application where this laser may be able to improve clinical practice. The laser together with scanning galvanometer mirrors is used to cut precisely around small footprint vessels in tissue phantoms without leaving any visible residual thermal damage. These experiments provide proof-of-principle that this laser has promising potential in the laser surgery application space.

  8. Ocular safety limits for 1030nm femtosecond laser cataract surgery

    NASA Astrophysics Data System (ADS)

    Wang, Jenny; Sramek, Christopher; Paulus, Yannis M.; Lavinsky, Daniel; Schuele, Georg; Anderson, Dan; Dewey, David; Palanker, Daniel V.

    2013-03-01

    Application of femtosecond lasers to cataract surgery has added unprecedented precision and reproducibility but ocular safety limits for the procedure are not well-quantified. We present an analysis of safety during laser cataract surgery considering scanned patterns, reduced blood perfusion, and light scattering on residual bubbles formed during laser cutting. Experimental results for continuous-wave 1030 nm irradiation of the retina in rabbits are used to calibrate damage threshold temperatures and perfusion rate for our computational model of ocular heating. Using conservative estimates for each safety factor, we compute the limits of the laser settings for cataract surgery that optimize procedure speed within the limits of retinal safety.

  9. Combined treatment with 595-nm pulsed dye laser and 1550-nm erbium-glass fractional laser for traumatic scars.

    PubMed

    Park, Kui Young; Hyun, Moo Yeol; Moon, Nam Ju; Jeong, Se Yeong; Seo, Seong Jun; Hong, Chang Kwun

    2016-11-01

    Facial scars can be caused by a traumatic event or indeed surgical procedures. Several treatment modalities have been suggested including surgical or resurfacing techniques, autologous fat transfer, and injection of fillers. However, these approaches have varying degrees of success and associated side effects. We report two Korean patients with traumatic scars. Both patients received combined consecutive treatment with 595-nm pulsed dye laser (PDL) and 1550-nm erbium-glass fractional laser. Both patients showed remarkable clinical improvements after a course of sessions. Therefore, simultaneous combined treatment with PDL and fractional laser may be considered a reasonable therapeutic option for traumatic facial scars.

  10. High power eye-safe Er3+:YVO4 laser diode-pumped at 976 nm and emitting at 1603 nm

    NASA Astrophysics Data System (ADS)

    Newburgh, G. A.; Dubinskii, M.

    2016-02-01

    We report on the performance of an eye-safe laser based on a Er:YVO4 single crystal, diode-pumped at 976 nm (4I15/2-->4I11/2 transition) and operating at 1603 nm (4I13/2-->4I15/2 transition) with good beam quality. A 10 mm long Er3+:YVO4 slab, cut with its c-axis perpendicular to the laser cavity axis, was pumped in σ-polarization and lased in π-polarization. The laser operated in a quasi-continuous wave (Q-CW) regime with nearly 9 W output power, and with a slope efficiency of about 39% with respect to absorbed power. This is believed to be the highest efficiency and highest power achieved from an Er3+:YVO4 laser pumped in the 970-980 nm absorption band.

  11. Advances in 193 nm excimer lasers for mass spectrometry applications

    NASA Astrophysics Data System (ADS)

    Delmdahl, Ralph; Esser, Hans-Gerd; Bonati, Guido

    2016-03-01

    Ongoing progress in mass analysis applications such as laser ablation inductively coupled mass spectrometry of solid samples and ultraviolet photoionization mediated sequencing of peptides and proteins is to a large extent driven by ultrashort wavelength excimer lasers at 193 nm. This paper will introduce the latest improvements achieved in the development of compact high repetition rate excimer lasers and elaborate on the impact on mass spectrometry instrumentation. Various performance and lifetime measurements obtained in a long-term endurance test over the course of 18 months will be shown and discussed in view of the laser source requirements of different mass spectrometry tasks. These sampling type applications are served by excimer lasers delivering pulsed 193 nm output of several mJ as well as fast repetition rates which are already approaching one Kilohertz. In order to open up the pathway from the laboratory to broader market industrial use, sufficient component lifetimes and long-term stable performance behavior have to be ensured. The obtained long-term results which will be presented are based on diverse 193 nm excimer laser tube improvements aiming at e.g. optimizing the gas flow dynamics and have extended the operational life the laser tube for the first time over several billion pulses even under high duty-cycle conditions.

  12. Brain lesion induced by 1319nm laser radiation

    NASA Astrophysics Data System (ADS)

    Yang, Zaifu; Chen, Hongxia; Wang, Jiarui; Chen, Peng; Ma, Ping; Qian, Huanwen

    2010-11-01

    The laser-tissue interaction has not been well defined at the 1319 nm wavelength for brain exposure. The goal of this research effort was to identify the behavioral and histological changes of brain lesion induced by 1319 nm laser. The experiment was performed on China Kunming mice. Unilateral brain lesions were created with a continuous-wave Nd:YAG laser (1319nm). The brain lesions were identified through behavioral observation and histological haematoxylin and eosin (H&E) staining method. The behavior change was observed for a radiant exposure range of 97~773 J/cm2. The histology of the recovery process was identified for radiant exposure of 580 J/cm2. Subjects were sacrificed 1 hour, 1 week, 2 weeks, 3 months, 7 months and 13 months after laser irradiation. Results showed that after laser exposure, behavioral deficits, including kyphosis, tail entasia, or whole body paralysis could be noted right after the animals recovered from anesthesia while gradually disappeared within several days and never recurred again. Histologically, the laser lesion showed a typical architecture dependent on the interval following laser treatment. The central zone of coagulation necrosis is not apparent right after exposure but becomes obvious within several days. The nerotic tissue though may persist for a long time, will finally be completely resorbed. No carbonization granules formed under our exposure condition.

  13. Excimer lasers for superhigh NA 193-nm lithography

    NASA Astrophysics Data System (ADS)

    Paetzel, Rainer; Albrecht, Hans S.; Lokai, Peter; Zschocke, Wolfgang; Schmidt, Thomas; Bragin, Igor; Schroeder, Thomas; Reusch, Christian; Spratte, Stefan

    2003-06-01

    Excimer lasers are widely used as the light source for microlithography scanners. The volume shipment of scanner systems using 193nm is projected to begin in year 2003. Such tools will directly start with super high numerical aperture (NA) in order to take full advantage of the 193nm wavelength over the advanced 248nm systems. Reliable high repetition rate laser light sources enabling high illumination power and wafer throughput are one of the fundamental prerequisites. In addition these light sources must support a very high NA imaging lens of more than 0.8 which determines the output spectrum of the laser to be less than 0.30 pm FWHM. In this paper we report on our recent progress in the development of high repetition rate ultra-narrow band lasers for high NA 193nm microlithography scanners. The laser, NovaLine A4003, is based on a Single Oscillator Ultral Line-narrowed (SOUL) design which yields a bandwidth of less than 0.30pm FWHM. The SOUL laser enables superior optical performance without adding complexity or cost up to the 4 kHz maximum repetition rate. The A4003's high precision line-narrowing optics used in combination with the high repetition rate of 4 kHz yields an output power of 20 W at an extremely narrow spectral bandwidth of less than 0.30 pm FWHM and highest spectral purity of less than 0.75 pm for the 95% energy content. We present performance and reliability data and discuss the key laser parameters. Improvements in the laser-internal metrology and faster regulation control result in better energy stability and improved overall operation behavior. The design considerations for line narrowing and stable laser operation at high repetition rates are discussed.

  14. 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.

  15. Measured skin damage thresholds for 1314-nm laser exposures

    NASA Astrophysics Data System (ADS)

    Montes de Oca, Cecilia I.; Cain, Clarence P.; Schuster, Kurt J.; Stockton, Kevin; Thomas, James J.; Eggleston, Thomas A.; Roach, William P.

    2003-06-01

    The use of lasers in the infrared region between 1200-1400 nm has steadily increased in various industrial and commercial applications. However, there are few studies documenting damage thresholds for the skin in this region, and current laser safety standards are based on limited data. This study has determined preliminary skin damage thresholds for the Effective Dose for 50% probability (ED50) of a Minimum Visible Lesion (MVL) with laser exposure at 1314nm and 0.35 ms pulse width. An in-vivo pigmented animal model, Yucatan mini-pig (Sus scrofa domestica), was used in this study. The type and extent of tissue damage in the porcine skin was determined through histopathologic examination, and the findings are discussed. Finally, the results of this study were compared to other literature as well as to the existing ANSI Z136.1 (2000) standard for safe use of lasers.

  16. Single, composite, and ceramic Nd:YAG 946-nm lasers

    NASA Astrophysics Data System (ADS)

    Lan, Rui-Jun; Yang, Guang; Zheng-Ping, Wang

    2015-06-01

    Single, composite crystal and ceramic continuous wave (CW) 946-nm Nd:YAG lasers are demonstrated, respectively. The ceramic laser behaves better than the crystal laser. With 5-mm long ceramic, a CW output power of 1.46 W is generated with an optical conversion efficiency of 13.9%, while the slope efficiency is 17.9%. The optimal ceramic length for a 946-nm laser is also calculated. Project supported by the National Natural Science Foundation of China (Grant No. 61405171), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ014), and the Science and Technology Program of the Shandong Higher Education Institutions of China (Grant No. J13LJ05).

  17. Enhancement of 800 nm upconversion emission in a thulium doped tellurite microstructured fiber pumped by a 1560 nm femtosecond fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Zhixu; Yao, Chuanfei; Wang, Shunbin; Zheng, Kezhi; Xiong, Liangming; Luo, Jie; Lv, Dajuan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-04-01

    We report enhanced upconversion (UC) fluorescence in Tm3+ doped tellurite microstructured fibers (TDTMFs) fabricated by using a rod-in-tube method. Under the pumping of a 1560 nm femtosecond fiber laser, ultrabroadband supercontinuum light expanding from ˜1050 to ˜2700 nm was generated in a 4 cm long TDTMF. Simultaneously, intense 800 nm UC emission from the 3H4 → 3H6 transition of Tm3+ was observed in the same TDTMF. Compared to that pumped by a 1560 nm continuous wave fiber laser, the UC emission intensity was enhanced by ˜4.1 times. The enhancement was due to the spectral broadening in the TDTMF under the pumping of the 1560 nm femtosecond fiber laser.

  18. Enhancement of 800 nm upconversion emission in a thulium doped tellurite microstructured fiber pumped by a 1560 nm femtosecond fiber laser

    SciTech Connect

    Jia, Zhixu; Zheng, Kezhi; Yao, Chuanfei; Wang, Shunbin; Qin, Guanshi Qin, Weiping; Xiong, Liangming; Luo, Jie; Lv, Dajuan; Ohishi, Yasutake

    2016-04-28

    We report enhanced upconversion (UC) fluorescence in Tm{sup 3+} doped tellurite microstructured fibers (TDTMFs) fabricated by using a rod-in-tube method. Under the pumping of a 1560 nm femtosecond fiber laser, ultrabroadband supercontinuum light expanding from ∼1050 to ∼2700 nm was generated in a 4 cm long TDTMF. Simultaneously, intense 800 nm UC emission from the {sup 3}H{sub 4} → {sup 3}H{sub 6} transition of Tm{sup 3+} was observed in the same TDTMF. Compared to that pumped by a 1560 nm continuous wave fiber laser, the UC emission intensity was enhanced by ∼4.1 times. The enhancement was due to the spectral broadening in the TDTMF under the pumping of the 1560 nm femtosecond fiber laser.

  19. Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

    NASA Astrophysics Data System (ADS)

    Yao, Y.; Ling, Zhao; Li, B.; Qu, D. P.; Zhou, K.; Zhang, Y. B.; Zhao, Y.; Zheng, Q.

    2013-03-01

    Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO4 laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO4 laser at 1086 nm.

  20. 810nm, 980nm, 1470nm and 1950nm diode laser comparison: a preliminary "ex vivo" study on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Sozzi, Michele; Selleri, Stefano; Vescovi, Paolo; Cucinotta, Annamaria

    2015-02-01

    The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of "tissue respect", have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this "ex vivo" study, probably due to their greatest affinity to water.

  1. Experimental laser interstitial thermotherapy in ex-vivo porcine tissue at 980 nm and 830 nm

    NASA Astrophysics Data System (ADS)

    Salas, Nelson, Jr.; Manns, Fabrice; Parel, Jean-Marie A.; Milne, Peter J.; Minhaj, Ahmed M.; Denham, David B.; Robinson, David S.

    2001-05-01

    The purpose of these experiments was to compare the temperature increase in ex-vivo porcine mammary chain tissue as a breast tissue model during interstitial laser irradiation with diode lasers emitting at 980 nm and 830 nm. Both wavelengths were delivered at 4.0 W for 10 minutes through a diffusing fiber inserted into ex-vivo porcine tissue. The temperature was measured with a set of 15 thermocouples placed 5, 10, and 15 mm from the fiber axis. The initial rate of temperature increase 5 mm away from the fiber tip was higher at 980 nm (0.12 to 0.20 degree(s)C/s) than at 830 nm (0.10 to 0.16 degree(s)C/s). At 10 mm and 15 mm (areas with less radiation), the rate was smaller than at 5 mm (less than 0.06 degree(s)C/s at 10 mm and less than 0.02 degree(s)C/s at 15 mm) for both wavelengths with no significant difference between the 980 nm and 830 nm radiation. The temperature increase at 5, 10 and 15 mm away from the fiber tip after 10 minutes of irradiation was higher at 980 nm (36 to 45 degree(s)C at 5 mm, 14 to 30 degree(s)C at 10 mm and 9 to 17 degree(s)C at 15 mm) than at 830 nm (27 to 33 degree(s)C at 5 mm, 11 to 17 degree(s)C at 10 mm and 8 to 9 degree(s)C at 15 mm) after 10 minutes. These results were found to be highly dependent on tissue composition (muscle vs. fatty tissue).

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

    PubMed

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

    2013-07-01

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

  3. A 15 W 1152 nm Raman fiber laser with 6 nm spectral width for Ho3+-doped crystal's pumping source

    NASA Astrophysics Data System (ADS)

    Chen, Xiuyan; Jiang, Huawei

    2016-12-01

    A 11.5 W 1152 nm Raman fiber laser with 6 nm spectral width was demonstrated based on the resonator constructed with one fiber loop mirror and one fiber Bragg grating. By mans of experimental measurement and theoretical calculation, the reflectivity of the fiber loop mirror was confirmed as 0.93. The Yb3+-doped 1090 nm fiber length was about 5 m. When the maximum pumping power of 976 nm laser was 54.8 W, 32.2 W 1090 nm laser was obtained and the optical to optical conversion efficiency from 1090 nm to 1152 nm light was 48%. Finally, the 1152 nm Raman fiber laser was used for pumping Ho3+:LLF crystal, and the 1194 nm fluorescence emission peak was detected for the first time.

  4. 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.

  5. High average power, narrow band 248 nm alexandrite laser system

    SciTech Connect

    Kuper, J.W.; Chin, T.C.; Papanestor, P.A.

    1994-12-31

    A compact line-narrowed 248 nm solid state laser source operating at 15 mJ {at} 100 Hz PRF was demonstrated. Constraints due to thermal loading of components were addressed. Tradeoffs between pulse energy and repetition rate were investigated. A method for overcoming thermal dephasing in the THG material was achieved by scanning a slab shaped crystal.

  6. Power scaling of laser diode pumped Pr3+:LiYF4 cw lasers: efficient laser operation at 522.6 nm, 545.9 nm, 607.2 nm, and 639.5 nm.

    PubMed

    Gün, Teoman; Metz, Philip; Huber, Günter

    2011-03-15

    We report efficient cw laser operation of laser diode pumped Pr(3+)-doped LiYF4 crystals in the visible spectral region. Using two InGaN laser diodes emitting at λ(P)=443.9 nm with maximum output power of 1 W each and a 2.9-mm-long crystal with a doping concentration of 0.5%, output powers of 938 mW, 418 mW, 384 mW, and 773 mW were achieved for the laser wavelengths 639.5 nm, 607.2 nm, 545.9 nm, and 522.6 nm, respectively. The maximum absorbed pump powers were approximately 1.5 W, resulting in slope efficiencies of 63.6%, 32.0%, 52.1%, and 61.5%, as well as electro-optical efficiencies of 9.4%, 4.2%, 3.8%, and 7.7%, respectively. Within these experiments, laser diode-pumped laser action at 545.9 nm was demonstrated for what is believed to be the first time.

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

    PubMed

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

    2015-01-01

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

  8. Novel 980-nm and 490-nm light sources using vertical cavity lasers with extended coupled cavities

    NASA Astrophysics Data System (ADS)

    McInerney, John G.; Mooradian, Aram; Lewis, Alan; Shchegrov, Andrei V.; Strzelecka, Eva M.; Lee, Dicky; Watson, Jason P.; Liebman, Michael K.; Carey, Glen P.; Umbrasas, Arvydas; Amsden, Charles A.; Cantos, Brad D.; Hitchens, William R.; Heald, David L.; Doan, Vincent V.; Cannon, J. L.

    2003-04-01

    We have developed novel electrically pumped, surface-emitting lasers emitting at 980 nm with an extended coupled cavity. The concept is scalable from monolithic low power devices all the way to high power extended cavity lasers. The latter have demonstrated 1W cw multi-mode and 0.5 W cw in a TEM00 mode and a single frequency, with 90% coupling efficiency into a single-mode fiber. By inserting a nonlinear optical medium in the external cavity, efficient and compact frequency doubling has been achieved with CW output powers 5-40 mW demonstrated at 490 nm. The latter devices are especially noteworthy due to their very low noise, sub 10 μrad beam pointing stability combined with small size, low power consumption and high efficiency.

  9. High power narrowband 589 nm frequency doubled fibre laser source.

    PubMed

    Taylor, Luke; Feng, Yan; Calia, Domenico Bonaccini

    2009-08-17

    We demonstrate high-power high-efficiency cavity-enhanced second harmonic generation of an in-house built ultra-high spectral density (SBS-suppressed) 1178 nm narrowband Raman fibre amplifier. Up to 14.5 W 589 nm CW emission is achieved with linewidth Delta nu(589) < 7 MHz in a diffraction-limited beam, with peak external conversion efficiency of 86%. The inherently high spectral and spatial qualities of the 589 nm source are particularly suited to both spectroscopic and Laser Guide Star applications, given the seed laser can be easily frequency-locked to the Na D(2a) emission line. Further, we expect the technology to be extendable, at similar or higher powers, to wavelengths limited only by the seed-pump-pair availability. (c) 2009 Optical Society of America

  10. Treatment of oral lichen planus using 308-nm excimer laser.

    PubMed

    Liu, Wei-Bing; Sun, Li-Wei; Yang, Hua; Wang, Yan-Fei

    2017-08-23

    Oral lichen planus (OLP) is a chronic inflammatory disease, has prolonged courses, repeated attacks and resistance to treatment. The traditional narrow spectrum UVB treatment has an established efficacy on skin lichen planus, and high safety. However, most of ultraviolet phototherapy devices have a huge volume, thereby cannot be used in the treatment of OLP. Lymphocytic infiltration is evident in the lesions of lichen planus, and the direct irradiation of 308-nm excimer laser can induce apoptosis of the T lymphocytes in skin lesions, thereby has a unique therapeutic effect on the diseases involving T lymphocytes. This study aims to investigate the efficacy of 308-nm excimer laser in the treatment of OLP. A total of six OLP patients were enrolled into this study, and further pathological diagnosis was conducted, then 308-nm excimer laser was used in the treatment. The efficacy of 308-nm excimer laser in the treatment of OLP was satisfactory. The clinical symptoms of five patients were significantly improved. In two patients, the erosion surface based on congestion and the surrounding white spots completely disappeared, and clinical recovery was achieved. Three patients achieved partial remission, that is, the erosion surface healed, congestion and white spot area shrunk by more than 1/2 of the primary skin lesions. In the remaining one patient, the erosion surface had not completely healed after treatment, and congestion and white spot area shrunk by less than 1/2 of the primary skin lesions. Only one patients had developed mild pain during the treatment, and this symptom alleviated by itself. The 308-nm excimer laser therapy can serve as a safe and effective treatment for OLP. © 2017 Wiley Periodicals, Inc.

  11. Laser Nd:YVO{4} impulsionnel à 914 nm pompé par diode

    NASA Astrophysics Data System (ADS)

    Blandin, P.; Druon, F.; Balembois, F.; Georges, P.; Lévêque-Fort, S.; Fontaine-Aupart, M. P.

    2006-10-01

    Nous présentons ici le premier laser impulsionnel à verrouillage de modes en phase passif directement pompé par diode, utilisant la transition 4F{3 / 2}-4I{9/2} de l'ion néodyme à 914 nm. Le système de pompage utilisé permet d'obtenir un dispositif simple. Le train d'impulsions est obtenu grâce à un miroir à absorbant saturable, l'émission laser à 914 nm étant privilégiée par l'introduction dans la cavité de fortes pertes à 1064 nm. Nous obtenons avec notre dispositif des impulsions à 913.8 nm, de durée 8.8 ps à une cadence de 94 MHz et à une puissance de 86 mW.

  12. Laser ablation of sub-10 nm silver nanoparticles

    DOE PAGES

    Zinovev, Alexander; Moore, Jerome F.; Baryshev, Sergey V.; ...

    2017-04-13

    Laser ablation of silver nanoparticles (NPs) was studied with laser post-ionization (LPI) time-of-flight mass spectrometry (TOF MS). Silver NPs containing ~15 000 Ag atoms (4 nm radius) were deposited by soft landing (energy 3 eV/atom) onto indium tin oxide (ITO)/glass substrates. Laser ablation was performed using frequency-doubled Ti:sapphire nanosecond pulsed laser irradiation at three different wavelengths (371, 401, and 421 nm), whereas for post-ionization, pulses from an F2 laser were used. Laser fluences and time delay dependencies of Ag and In signals were obtained. Using these data, the temperature of the desorption source as well as its time duration weremore » calculated. It was found that the peak temperature of NPs was above their melting point and they cooled down slowly, with temperature decay time of several hundreds of nanoseconds. This anomalous behavior was explained based on a model where the semiconducting ITO substrate is initially transparent to the desorption laser radiation but starts to adsorb it due to the temperature increase arising from heat exchange with NPs. Poor heat conduction in the ITO film creates conditions for long-lived hot spots on the surface and initiates further optical damage of the substrate. No difference in the ablation process due to plasmon resonance was detected, likely due to thermal expansion and melting of NPs during laser irradiation, which then broadens the plasmon absorption band enough to cover all wavelengths used. Here, these results clearly demonstrate that the process of NP interaction with laser radiation is governed not only by initial optical and thermophysical parameters of NPs and the surrounding media, but also by their alteration due to temperature increases during the irradiation process.« less

  13. GENERAL: A diode laser spectrometer at 634 nm and absolute frequency measurements using optical frequency comb

    NASA Astrophysics Data System (ADS)

    Yi, Lin; Yuan, Jie; Qi, Xiang-Hui; Chen, Wen-Lan; Zhou, Da-Wei; Zhou, Tong; Zhou, Xiao-Ji; Chen, Xu-Zong

    2009-04-01

    This paper reports that two identical external-cavity-diode-laser (ECDL) based spectrometers are constructed at 634 nm referencing on the hyperfine B-X transition R(80)8-4 of 127I2. The lasers are stabilized on the Doppler-free absorption signals using the third-harmonic detection technique. The instability of the stabilized laser is measured to be 2.8 × 10-12 (after 1000 s) by counting the beat note between the two lasers. The absolute optical frequency of the transition is, for the first time, determined to be 472851936189.5 kHz by using an optical frequency comb referenced on the microwave caesium atomic clock. The uncertainty of the measurement is less than 4.9 kHz.

  14. 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.

  15. 551 nm Generation by sum-frequency mixing of intracavity pumped Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Li, S. T.; Zhang, X. H.

    2012-02-01

    We present for the first time a Nd:YAG laser emitting at 1319 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1319 nm intracavity pumped at 946 nm. Intracavity sumfrequency mixing at 946 and 1319 nm was then realized in a LBO crystal to reach the yellow range. We obtained a continuous-wave output power of 158 mW at 551 nm with a pump laser diode emitting 18.7 W at 809 nm.

  16. 980 nm narrow linewidth Yb-doped phosphate fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Yao, Yifei; Hu, Haowei; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Zhang, Guangju

    2014-12-01

    A narrow-linewidth ytterbium (Yb)-doped phosphate fiber laser based on fiber Bragg grating (FBG) operating around 980 nm is reported. Two different kinds of cavity are applied to obtain the 980 nm narrow-linewidth output. One kind of the cavity consists of a 0.35 nm broadband lindwidth high-reflection FBG and the Yb-doped phosphate fiber end with 0° angle, which generates a maximum output power of 25 mW. The other kind of resonator is composed of a single mode Yb-doped phosphate fiber and a pair of FBGs. Over 10.7 mW stable continuous wave are obtained with two longitudinal modes at 980 nm. We have given a detailed analysis and discussion for the results.

  17. Laser-Matter Interactions with a 527 nm Drive

    SciTech Connect

    Glenzer, S; Niemann, C; Witman, P; Wegner, P; Mason, D; Haynam, C; Parham, T; Datte, P

    2007-02-16

    The primary goal of this Exploratory Research is to develop an understanding of laser-matter interactions with 527-nm light (2{omega}) for studies of interest to numerous Laboratory programs including inertial confinement fusion (ICF), material strength, radiation transport, and hydrodynamics. In addition, during the course of this work we will develop the enabling technology and prototype instrumentation to diagnose a high fluence laser beam for energy, power, and near field intensity profile at 2{omega}. Through this Exploratory Research we have established an extensive experimental and modeling data base on laser-matter interaction with 527 nm laser light (2{omega}) in plasma conditions of interest to numerous Laboratory programs. The experiments and the laser-plasma interaction modeling using the code pF3D have shown intensity limits and laser beam conditioning requirements for future 2{omega} laser operations and target physics experiments on the National Ignition Facility (NIF). These findings have set requirements for which present radiation-hydrodynamic simulations indicate the successful generation of relevant pressure regimes in future 2{omega} experiments. To allow these experiments on the NIF, optics and optical mounts were prepared for the 18mm Second Harmonic Generation Crystal (SHG crystal) that would provide the desired high conversion efficiency from 1{omega} to 2{omega}. Supporting experimental activities on NIF included high-energy 1{omega} shots at up to 22kJ/beamline (4MJ full NIF 1{omega} equivalent energy) that demonstrated, in excess, the 1{omega} drive capability of the main laser that is required for 2{omega} operations. Also, a very extensive 3{omega} campaign was completed (see ''The National Ignition Facility Laser Performance Status'' UCRL-JRNL-226553) that demonstrated that not only doubling the laser, but also tripling the laser (a much more difficult and sensitive combination) met our model predictions over a wide range of laser

  18. Efficient and compact intracavity-frequency-doubled Nd:LuVO4/LBO laser at 538 nm end-pumped by a fiber-coupled laser diode

    NASA Astrophysics Data System (ADS)

    Liu, B.; Li, Y. L.; Jiang, H. L.

    2011-10-01

    We report a diode-pumped Nd:LuVO4 laser emitting at 1076 nm, based on the 4 F 3/2-4 I 11/2 transition, generally used for a 1066 nm emission. A power of 689 mW at 1076 nm has been achieved in continuous-wave (CW) operation with a fiber-coupled laser diode emitting 17.8 W at 809 nm. Intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 105 mW at 538 nm by using a LiB3O5 (LBO) nonlinear crystal.

  19. Interaction of pulse laser radiation of 532 nm with model coloration layers for medieval stone artefacts

    NASA Astrophysics Data System (ADS)

    Colson, J.; Nimmrichter, J.; Kautek, W.

    2014-05-01

    Multilayer polychrome coatings on medieval and Renaissance stone artefacts represent substantial challenges in laser cleaning. Therefore, polychromic models with classical pigments, minium Pb22+PbO, zinc white (ZnO), and lead white ((PbCO3)2·Pb(OH)2) in an acrylic binder, were irradiated with a Q-switched Nd:YAG laser emitting at 532 nm. The studied medieval pigments exhibit strongly varying incubation behaviours directly correlated to their band gap energies. Higher band gaps beyond the laser photon energy of 2.3 eV require more incubative generation of defects for resonant transitions. A matching of the modification thresholds after more than four laser pulses was observed. Laser cleaning with multiple pulsing should not exceed ca. 0.05 J/cm2 when these pigments coexist in close spatial proximity.

  20. High-efficiency high-brightness diode lasers at 1470 nm/1550 nm for medical and defense applications

    NASA Astrophysics Data System (ADS)

    Gallup, Kendra; Ungar, Jeff; Vaissie, Laurent; Lammert, Rob; Hu, Wentao

    2012-03-01

    Diode lasers in the 1400 nm to 1600 nm regime are used in a variety of applications including pumping Er:YAG lasers, range finding, materials processing, aesthetic medical treatments and surgery. In addition to the compact size, efficiency, and low cost advantages of traditional diode lasers, high power semiconductor lasers in the eye-safe regime are becoming widely used in an effort to minimize the unintended impact of potentially hazardous scattered optical radiation from the laser source, the optical delivery system, or the target itself. In this article we describe the performance of high efficiency high brightness InP laser bars at 1470nm and 1550nm developed at QPC Lasers for applications ranging from surgery to rangefinding.

  1. Internal defect localization in 980 nm ridge waveguide lasers

    NASA Astrophysics Data System (ADS)

    Díaz, L.; Eichler, H. J.; Weich, K.; Klehr, A.; Zeimer, U.

    2006-04-01

    High power lasers emitting at 980 nm are essential for pumping sources of erbium-doped fiber amplifiers (EDFAs). These are used in longer distance telecommunications. Stability and reliability of the modules are two key characteristics. The present paper investigates 'sudden random failures' of double quantum-well 980 nm high power ridge waveguide lasers implemented in EDFAs. For the inspection of the external and internal status of the device we used optical spectrum modulation experiments, electroluminescence measurements, scanning electron microscopy and cathodoluminescence investigations. The localization of internal defects is the main point of this work. Two different 'sudden random failures' were found: catastrophical optical mirror damage (COMD) and internal dark line defect (DLD) formation.

  2. Machining of optical microstructures with 157 nm laser radiation

    NASA Astrophysics Data System (ADS)

    Temme, Thorsten; Ostendorf, Andreas; Kulik, Christian J.

    2003-11-01

    The precision machining of glass by laser ablation has been expanded with the short wavelength of the 157 nm of the F2 excimer laser. The high absorption of this wavelength in any optical glass, especially in UV-grade fused silica, offers a new approach to generate high quality surfaces, addressing also micro-optical components. In this paper, the machining of basic diffractive and refractive optical components and the required machining and process technology is presented. Applications that are addressed are cylindrical and rotational symmetrical micro lenses and diffractive optics like phase transmission grating and diffractive optical elements (DOEs). These optical surfaces have been machined into bulk material as well as on fiber end surfaces, to achieve compact (electro) -- optical elements with high functionality and packaging density. The short wavelength of 157 nm used in the investigations require either vacuum or high purity inert gas environments. The influence of different ambient conditions is presented.

  3. Long pulse KrCl excimer laser at 222 nm

    NASA Astrophysics Data System (ADS)

    Hueber, J.-M.; Fontaine, B. L.; Bernard, N.; Forestier, B. M.; Sentis, M. L.; Delaporte, Ph. C.

    1992-11-01

    A long pulse (up to 185 ns FWHM) KrCl laser at lambda = 222 nm has been achieved by combining X-ray preionization and double discharge (spiker/sustainer) with fast ferrite magnetic switch. A relatively low pumping power (0.5 to 1 MW/cu cm) and 25 cm gain length allows a maximum extracted energy of 115 mJ in 135 ns FWHM, with an overall energy efficiency of 0.75 percent.

  4. Quasi-cw 808-nm 300-W laser diode arrays

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Kozyrev, A. A.; Kondakova, N. S.; Kondakov, S. A.; Krokhin, O. N.; Mikaelyan, G. T.; Oleshchenko, V. A.; Popov, Yu. M.; Cheshev, E. A.

    2017-02-01

    Samples of 808-nm quasi-cw laser diode arrays (LDAs) with an output power exceeding 300 W, a pulse duration of 200 μs, and a pulse repetition rate of 100 Hz are developed and fabricated. The main output parameters of a set of five LDAs, including light – current characteristics, current – voltage characteristics, and emission spectra are measured. Preliminary life tests show that the LDA power remains stable for 108 pulses.

  5. 494 nm blue laser based on sum-frequency mixing of diode pumped Nd3+ lasers

    NASA Astrophysics Data System (ADS)

    Zou, J.; Wang, L. R.

    2012-02-01

    We report for the first time a continuous-wave (CW) blue radiation at 494 nm by intracavity sumfrequency generation of 912 nm Nd:GdVO4 laser and 1079 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 494 nm blue laser was obtained by 912 and 1079 nm intra-cavity sum-frequency mixing, and output power of 179 mW was demonstrated. At the output power level of 179 mW, the output power stability is better than 3.5% and laser beam quality M 2 factor is 1.21.

  6. 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.

  7. Auditory nerve impulses induced by 980 nm laser.

    PubMed

    Guan, Tian; Zhu, Kai; Chen, Fei; He, Yonghong; Wang, Jian; Wu, Mocun; Nie, Guohui

    2015-08-01

    The discovery that a pulsed laser could trigger an auditory neural response inspired ongoing research on cochlear implants activated by optical stimulus rather than by electrical current. However, most studies to date have used visible light (532 nm) or long-wavelength near-infrared (>1840  nm ) and involved making a hole in the cochlea. This paper investigates the effect of optical parameters on the optically evoked compound action potentials (oCAPs) from the guinea pig cochlea, using a pulsed semiconductor near-infrared laser (980 nm) without making a hole in the cochlea. Synchronous trigger laser pulses were used to stimulate the cochlea, before and after deafening, upon varying the pulse duration (30–1000  μs ) and an amount of radiant energy (0–53.2  mJ/cm 2 ). oCAPs were successfully recorded after deafening. The amplitude of the oCAPs increased as the infrared radiant energy was increased at a fixed 50  μs pulse duration, and decreased with a longer pulse duration at a fixed 37.1  mJ/cm 2 radiant energy. The latency of the oCAPs shortened with increasing radiant energy at a fixed pulse duration. With a higher stimulation rate, the amplitude of the oCAPs’ amplitude decreased.

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

    PubMed

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

    2017-07-13

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

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

    PubMed Central

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

    2017-01-01

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

  10. 450 nm diode laser: A new help in oral surgery

    PubMed Central

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

    2016-01-01

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

  11. Dissociative ionization of CH2Br2 in 800 and 400 nm femtosecond laser fields

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Yang, Yan; Li, Zhipeng; Sun, Zhenrong

    2017-10-01

    We experimentally demonstrate the dissociative ionization of CH2Br2 molecules irritated by 800 and 400 nm femtosecond laser fields using time-of-flight mass spectra and dc-sliced ion imaging technology. Our results show that in both laser fields, CH2Br2 can ionize to CH2Br2+, then CH2Br2+ break one Csbnd Br bond to produce fragments CH2Br(+) and Br(+). The charge assignment is determined by the ionization energy of the fragments. Additionally, in 400 nm laser fields, the CH2Br2+ can overpass a transition state to form an intermediate CH2Brsbnd Br+, then the intermediate break Csbnd Br bond to produce Br2 or Br2+ via elimination channel.

  12. Solid sampling with 193-nm excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Delmdahl, Ralph

    2007-02-01

    Reproducible and sensitive elemental analysis of solid samples is a crucial task in areas of geology (e.g. microanalysis of fluid inclusions), material sciences, industrial quality control as well as in environmental, forensic and biological studies. To date the most versatile detection method is mass-spectroscopic multi-element analysis. In order to obtain reproducible results, this requires transferring the solid sample into the gas-phase while preserving the sample's stoichiometric composition. Laser ablation in combination with Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is a proven powerful technique to meet the requirements for reliable solid sample analysis. The sample is laser ablated in an air-tight cell and the aerosol is carried by an inert gas to a micro-wave induced plasma where its constituents are atomized and ionized prior to mass analysis. The 193 nm excimer laser ablation, in particular, provides athermal sample ablation with very precise lateral ablation and controlled depth profiling. The high photon energy and beam homogeneity of the 193 nm excimer laser system avoids elemental fractionation and permits clean ablation of even transmissive solid materials such as carbonates, fluorites and pure quartz.

  13. Making transmission and reflection holograms using 650 nm laser diode from laser pointer

    NASA Astrophysics Data System (ADS)

    Panin, Alexander; Brown, Eric; Martinez, Tracy; Panin, Dmitry

    2003-10-01

    We have made both transmission and reflection holograms using inexpensive set-up with a 5 mW, 650-nm diode InGaAlP laser (similar to lasers used in common red laser pointers and DVD players). The reflection holograms can be viewed both with laser sourses of light and with non-coherent moderately collimated natural sources (like Sun or light bulb). In the transmission holograms viewed with laser both real and virtual images can be seen. Our paper presents the description of experimental set-up of exposure and development techniques, and the discussion of controversial coherence length issue of laser diodes as it applies to holograms.

  14. Diode-pumped passively mode-locked Nd:GSAG laser at 942 nm.

    PubMed

    Xu, Changwen; Wei, Zhiyi; Zhang, Yongdong; Li, Dehua; Zhang, Zhiguo; Wang, X; Wang, S; Eichler, H J; Zhang, Chunyu; Gao, Chunqing

    2009-08-01

    Stable mode-locking of a diode-pumped Nd:GSAG laser emitting at 942 nm between the 4F2/3-4I9/2 transition has been demonstrated. With a z cavity and a semiconductor saturable absorber mirror passive mode locker, we obtained 8.7 ps pulses at repetition rate of 95.6 MHz and average output power of 510 mW. The total optical efficiency is about 3.1%.

  15. Atomic Beam Spectroscopy of the 1283 nm M1 Transition in Thallium

    NASA Astrophysics Data System (ADS)

    Majumder, P. K.; Holmes, C. D.; Green, Michael

    2003-05-01

    Using a new thallium atomic beam apparatus, we are undertaking a series of laser spectroscopy measurements with the goal of providing precise, independent cross-checks on the accuracy of new calculations of parity nonconservation in thallium(M. Kozlov et al.), Phys Rev. A64, 053107 (2001). In our apparatus, a laser beam interacts transversely with a 2-cm-wide thallium beam of density 4x10^11 cm-3 and reveals roughly tenfold Doppler narrowing of the absorption profile. Having completed a new 0.4% measurement of the scalar Stark shift within the 378 nm 6P_1/2-7S_1/2 E1transition(S.C. Doret et al.), Phys. Rev. A66, 052504 (2002), we have now begun to study the very weak 1283 nm 6P_1/2-6P_3/2 transition in the atomic beam environment. We will determine both the scalar and tensor Stark shift components, as well as the various components of the Stark-induced amplitude within this mixed M1/E2 transition. To enhance the visibility of the weak absorption signal, we are employing an FM spectroscopy technique. The demodulated laser transmission spectrum provides a zero-background signal with high signal/noise and includes copies of the atomic absorption spectrum separated by well-known RF sideband frequencies, offering built-in frequency scale calibration. In the longer term, we are developing an atomic beam experiment using this same 1283 nm laser to search for a long-range T-odd, but P-even interaction in thallium.

  16. Frequency stabilization of an external cavity diode laser to molecular iodine at 657.483 nm.

    PubMed

    Fang, Hui-Mei; Wang, Shing-Chung; Shy, Jow-Tsong

    2006-05-01

    The saturation spectrum of the P(84) 5-5 transition of 127I2 at 657.483 nm is obtained with the third-harmonic demodulation method using an external cavity diode laser. The laser frequency is modulated by modulating the diode current instead of modulating the cavity length with a piezoelectric transducer (PZT). Current modulation allows a modulation frequency that is higher than PZT modulation. The signal-to-noise ratio of 1000 is better than previous results presented in the literature. The laser is frequency stabilized to the hyperfine component o of the P(84) 5-5 transition with a frequency stability of better than 10 kHz (2.2 x 10(-11) relative stability).

  17. 980-nm diode laser and fiber optic resectoscope in endourological surgery

    NASA Astrophysics Data System (ADS)

    Cecchetti, Walter; Guazzieri, Stefano; Tasca, Andrea; Dal Bianco, M.; Zattoni, Filiberto; Pagano, Francesco

    1996-12-01

    The 980 nm Ceralas D50 diode laser, produces homogeneous lesions on tissues of different nature. In our endourological tests we used the Ceralas D50 coupled with Comeg 24 ch laser resectoscope, and we treated 22 patients: n.5 bladder cancers, n.3 uretero pelvic junction obstructions, with hydronephrosis, n.3 urethra stenosis, n1 ureter stenosis, n.4 multiple upper tract transitional cell carcinomas, n.6 BPH treatments with VLAP modalities. Using the 1000 micrometers delivery fibers with different shaped tips, we obtained a bloodless sharp cut and easily vaporizations with minimum carbonizations, with power output in the range of 8-12 W, and 18-24W for VLAP.

  18. Recent brightness improvements of 976 nm high power laser bars

    NASA Astrophysics Data System (ADS)

    Bachmann, Alexander; Lauer, Christian; Furitsch, Michael; König, Harald; Müller, Martin; Strauß, Uwe

    2017-02-01

    Pump modules for fiber lasers and fiber-coupled direct diode laser systems require laser diodes with a high beam quality. While in fast axis direction diode lasers exhibit a nearly diffraction limited output beam, the maximum usable output power is usually limited by the slow axis divergence blooming at high power levels. Measures to improve the lateral beam quality are subject of extensive research. Among the many influencing factors are the chip temperature, thermal crosstalk between emitters, thermal lensing, lateral waveguiding and lateral mode structure. We present results on the improvements of the lateral beam divergence and brightness of gain-guided mini-bars for emission at 976 nm. For efficient fiber coupling into a 200 μm fiber with NA 0.22, the upper limit of the lateral beam parameter product is 15.5 mm mrad. Within the last years, the power level at this beam quality has been improved from 44 W to 52 W for the chips in production, enabling more cost efficient pump modules and laser systems. Our work towards further improvements of the beam quality focuses on advanced chip designs featuring reduced thermal lensing and mode shaping. Recent R&D results will be presented, showing a further improvement of the beam quality by 15%. Also, results of a chip design with an improved lateral emitter design for highest brightness levels will be shown, yielding in a record high brightness saturation of 4.8 W/mm mrad.

  19. High-power pulsed 976-nm DFB laser diodes

    NASA Astrophysics Data System (ADS)

    Zeller, Wolfgang; Kamp, Martin; Koeth, Johannes; Worschech, Lukas

    2010-04-01

    Distributed feedback (DFB) laser diodes nowadays provide stable single mode emission for many different applications covering a wide wavelength range. The available output power is usually limited because of catastrophical optical mirror damage (COD) caused by the small facet area. For some applications such as trace gas detection output powers of several ten milliwatts are sufficiently high, other applications like distance measurement or sensing in harsh environments however require much higher output power levels. We present a process combining optimizations of the layer structure with a new lateral design of the ridge waveguide which is fully compatible with standard coating and passivation processes. By implementing a large optical cavity with the active layer positioned not in the middle of the waveguide layers but very close to the upper edge, the lasers' farfield angles can be drastically reduced. Furthermore, the travelling light mode can be pushed down into the large optical cavity by continuously decreasing the ridge waveguide width towards both laser facets. The light mode then spreads over a much larger area, thus reducing the surface power density which leads to significantly higher COD thresholds. Laterally coupled DFB lasers based on this concept emitting at wavelengths around 976 nm yield hitherto unachievable COD thresholds of 1.6 W under pulsed operation. The high mode stability during the 50 ns pulses means such lasers are ideally suited for high precision distance measurement or similar tasks.

  20. 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

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

    PubMed

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

    2013-06-01

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

  2. 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.

  3. 555 nm laser sources based on intracavity frequency doubling of Nd:YGG laser

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    We report for the first time a yellow-green laser at 555 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1110 nm Nd-doped yttrium gallium garnet (Nd:YGG) laser under in-band diode pumping at 808 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 2.31 W of CW output power at 555 nm is achieved. The optical-to-optical conversion efficiency is up to 12.4%, and the fluctuation of the yellow-green output power was better than 2.8% in the given 4 h.

  4. Analysis of Cervical Supernatant Samples Luminescence Using 355 nm Laser

    NASA Astrophysics Data System (ADS)

    Vaitkuviene, A.; Gegzna, V.; Kurtinaitiene, R.; Stanikunas, R.; Rimiene, J.; Vaitkus, J.

    2010-05-01

    The biomarker discovery for accurate detection and diagnosis of cervical carcinoma and its malignant precursors represents one of the current challenges in clinical medicine. Laser induced autofluorescence spectra in cervical smear content were fitted to predict the cervical epithelium diagnosis as a lab off "optical biopsy" method. Liquid PAP supernatant sediment dried on Quartz plate spectroscopy was performed by 355 nm Nd YAG microlaser STA-1 (Standa, Ltd). For comparison a liquid supernatant spectroscopy was formed by laboratory "Perkin Elmer LS 50B spetrometer at 290, 300, 310 nm excitations. Analysis of spectrum was performed by approximation using the multi-peaks program with Lorentz functions for the liquid samples and with Gaussian functions for the dry samples. Ratio of spectral components area to the area under whole experimental curve (SPP) was calculated. The spectral components were compared by averages of SPP using Mann-Whitney U-test in histology groups. Results. Differentiation of Normal and HSIL/CIN2+ cases in whole supernatant could be performed by stationary laboratory lamp spectroscopy at excitation 290 nm and emission >379 nm with accuracy AUC 0,69, Sens 0,72, Spec 0,65. Differentiation Normal versus HSIL/CIN2+ groups in dried enriched supernatant could be performed by 355 nm microlaser excitation at emission 405-424 nm with accuracy (AUC 0,96, Sens 0,91, Spec 1.00). Diagnostic algorithm could be created for all histology groups differentiation under 355 nm excitation. Microlaser induced "optical biopsy "looks promising method for cervical screening at the point of care.

  5. Study of a Tm:Ho:YLF laser pumped by a Raman shifted erbium-doped fibre laser at 1678 nm

    SciTech Connect

    Kalachev, Yu L; Mikhailov, Viktor A; Podreshetnikov, V V; Shcherbakov, Ivan A

    2010-06-23

    The lasing, spectral, and luminescent characteristics of a Tm:Ho:YLF laser pumped by a Raman shifted erbium-doped fibre laser ({lambda} = 1678 nm) into the 1682-nm absorption line of the {sup 3}H{sub 6}-{sup 3}F{sub 4} transition of the Tm{sup 3+} ion are studied. It is shown that the total (with respect to the absorbed power) and slope laser efficiencies upon pulsed pumping reach 46% and 50%, respectively. The output radiation power in the cw regime is 400 mW. The comparative measurements showed that pumping by a fibre laser at 1678 nm is more efficient than diode pumping at 792 nm. (lasers)

  6. 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.

  7. 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.

  8. Pulsed dye laser treatment of pigmented lesions: a randomized clinical pilot study comparison of 607- and 595-nm wavelength lasers.

    PubMed

    Chern, Peggy L; Domankevitz, Yacov; Ross, E Victor

    2010-12-01

    The 595-nm pulsed dye laser has been used for the treatment of benign epidermal pigmented lesions (EPLs), but there is a risk of inducing undesirable purpura with treatment. To compare a 607-nm laser with a commercially-available 595-nm laser for the treatment of EPLs. Monte-Carlo simulations were performed to characterize laser interaction with skin. Ten patients with EPLs were treated with a 607-nm study prototype laser and the 595-nm pulsed dye laser twice at 2- to 4-week intervals on the left or right side on a randomized basis. Study endpoints included clearance rate of lesions, side effects immediately after treatment and at final follow-up, and patient discomfort/pain. Monte-Carlo simulations show that the 607-nm is absorbed more specifically by melanin than the 595-nm wavelength. Both lasers were effective in treatment of EPLs. The average degree of improvement overall was 41.2% with the 607-nm laser and 40% with the 595-nm laser. Patients reported less discomfort/pain during treatment with the 607-nm laser. Our findings suggest that the 607-nm laser is safe and at least as effective as the 595-nm laser in treatment of EPLs. There was less patient discomfort/pain during treatment using the 607-nm laser. Copyright © 2010 Wiley-Liss, Inc.

  9. Wavelength dependence on the forensic analysis of glass by nanosecond 266 nm and 1064 nm laser induced breakdown spectroscopy

    SciTech Connect

    Cahoon, Erica M.; Almirall, Jose R.

    2010-05-01

    Laser induced breakdown spectroscopy can be used for the chemical characterization of glass to provide evidence of an association between a fragment found at a crime scene to a source of glass of known origin. Two different laser irradiances, 266 nm and 1064 nm, were used to conduct qualitative and quantitative analysis of glass standards. Single-pulse and double-pulse configurations and lens-to-sample-distance settings were optimized to yield the best laser-glass coupling. Laser energy and acquisition timing delays were also optimized to result in the highest signal-to-noise ratio corresponding to the highest precision and accuracy. The crater morphology was examined and the mass removed was calculated for both the 266 nm and 1064 nm irradiations. The analytical figures of merit suggest that the 266 nm and 1064 nm wavelengths are capable of good performance for the forensic chemical characterization of glass. The results presented here suggest that the 266 nm laser produces a better laser-glass matrix coupling, resulting in a better stoichiometric representation of the glass sample. The 266 nm irradiance is therefore recommended for the forensic analysis and comparison of glass samples.

  10. Laser ablation of polymeric materials at 157 nm

    NASA Astrophysics Data System (ADS)

    Costela, A.; García-Moreno, I.; Florido, F.; Figuera, J. M.; Sastre, R.; Hooker, S. M.; Cashmore, J. S.; Webb, C. E.

    1995-03-01

    Results are presented on the ablation by 157 nm laser radiation of polytetrafluoroethylene (PTFE), polyimide, polyhydroxybutyrate (PHB), poly(methyl methacrylate) (PMMA), and poly(2-hydroxyethyl methacrylate) with 1% of ethylene glycol dimethacrylate as a crosslinking monomer. Direct photoetching of PHB and undoped PTFE is demonstrated for laser fluences ranging from 0.05 to 0.8 J/cm2. The dependence of the ablation process on the polymer structure is analyzed, and insight into the ablation mechanism is gained from an analysis of the data using Beer-Lambert's law and the kinetic model of the moving interface. Consideration of the absorbed energy density required to initiate significant ablation suggests that the photoetching mechanism is similar for all the polymers studied.

  11. High performance diode lasers emitting at 780-820 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; DeVito, M.; Grimshaw, M.; Leisher, P.; Zhou, H.; Dong, W.; Guan, X.; Zhang, S.; Martinsen, R.; Haden, J.

    2012-03-01

    High power 780-820 nm diode lasers have been developed for pumping and material processing systems. This paper presents recent progress in the development of such devices for use in high performance industrial applications. A newly released laser design in this wavelength range demonstrates thermally limited >25W CW power without catastrophic optical mirror damage (COMD), with peak wallplug efficiency ~65%. Ongoing accelerated lifetesting projects a time to 5% failure of ~10 years at 5 and 8 W operating powers for 95 and 200 μm emitter widths, respectively. Preliminary results indicate the presence and competition of a random and wear-out failure mode. Fiber-coupled modules based on arrays of these devices support >100W reliable operation, with a high 56% peak efficiency (ex-fiber) and improved brightness/reliability.

  12. Correlating Pulses from Two Spitfire, 800nm Lasers

    SciTech Connect

    Colby, Eric R.; Mcguinness, C.; Zacherl, W.D.; Plettner, T.; /Stanford U., Phys. Dept.

    2008-01-28

    The E163 laser acceleration experiments conducted at SLAC have stringent requirements on the temporal properties of two regeneratively amplified, 800nm, Spitfire laser systems. To determine the magnitude and cause of timing instabilities between the two Ti:Sapphire amplifiers, we pass the two beams through a cross-correlator and focus the combined beam onto a Hamamatsu G1117 photodiode. The photodiode has a bandgap such that single photon processes are suppressed and only the second order, two-photon process produces an observable response. The response is proportional to the square of the intensity. The diode is also useful as a diagnostic to determine the optimal configuration of the compression cavity.

  13. A stable 657nm laser for a Ca atom interferometer

    NASA Astrophysics Data System (ADS)

    Neyenhuis, Brian; Erickson, Christopher; Tang, Rebecca; Doermann, Greg; van Zijll, Marshall; Durfee, Dallin

    2006-05-01

    We will present an extremely stable laser to be used in an atom interferometer. A 657nm grating-stabilized diode laser is locked to a high-finesse cavity using the Pound-Drever-Hall method. Utilizing a feedback circuit with a bandwidth of 5 MHz we see a laser linewidth less than one kHz. In addition to a relatively high bandwidth, our circuit design allows for mode-hop-free scanning over a large range. We are also working on several improvements which should further reduce our linewidth; we are improving passive mechanical and thermal stability of the laser and the optical cavity and plan to change to a higher finesse cavity, we have designed and are testing a more stable current driver based on an updated Hall-Libbrecht design, and we calculating an optimized multiple-input feedback transfer function for our system. We will also present the measurement of the resonances of our optical cavity relative to the Ca intercombination line using a high-temperature vapor cell.

  14. 25 W Raman-fiber-amplifier-based 589 nm laser for laser guide star.

    PubMed

    Feng, Yan; Taylor, Luke R; Calia, Domenico Bonaccini

    2009-10-12

    We report on a 25 W continuous wave narrow linewidth (< 2.3 MHz) 589 nm laser by efficient (> 95%) coherent beam combination of two narrow linewidth (< 1.5 MHz) Raman fiber amplifiers with a Mach-Zehnder interferometer scheme and frequency doubling in an external resonant cavity with an efficiency of 86%. The results demonstrate the narrow linewidth Raman fiber amplifier technology as a promising solution for developing laser for sodium laser guide star adaptive optics.

  15. Subpicosecond 41.8-nm X-ray laser in the plasma produced by femtosecond laser irradiation of a xenon cluster jet

    SciTech Connect

    Ivanova, E P

    2012-12-31

    Model calculations are performed of the radiation gain for the 4d5d (J = 0) - 4d5p (J = 1) transition with a wavelength of 41.8 nm in Pd-like xenon ions in the plasma produced by femtosecond laser irradiation of a xenon cluster jet. Conditions for the excitation of an ultrashort-pulse ({approx}1 ps) X-ray laser are discussed. (lasers)

  16. Evaluation of dental pulp repair using low level laser therapy (688 nm and 785 nm) morphologic study in capuchin monkeys

    NASA Astrophysics Data System (ADS)

    Pretel, H.; Oliveira, J. A.; Lizarelli, R. F. Z.; Ramalho, L. T. O.

    2009-02-01

    The aim of this study was to evaluate the hypothesis that low-level laser therapy (LLLT) 688 nm and 785 nm accelerate dentin barrier formation and repair process after traumatic pulp exposure. The sample consisted of 45 premolars of capuchin monkeys (Cebus apella) with pulp exposure Class V cavities. All premolars were treated with calcium hydroxide (Ca(OH)2), divided in groups of 15 teeth each, and analyzed on 7th, 25th, and 60th day. Group GI - only Ca(OH)2, GII - laser 688 nm, and GIII - laser 785 nm. Laser beam was used in single and punctual dose with the parameters: continuous, 688 nm and 785 nm wavelength, tip's area of 0.00785 cm2, power 50 mW, application time 20 s, dose 255 J/cm2, energy 2 J. Teeth were capped with Ca(OH)2, Ca(OH)2 cement and restored with amalgam. All groups presented pulp repair. On 25th day the thickness of the formed dentin barrier was different between the groups GI and GII (p < 0.05) and between groups GI and GIII (p < 0.01). On 60th day there was difference between GI and GIII (p < 0.01). It may be concluded that, LLLT 688 nm and 785 nm accelerated dentin barrier formation and consequently pulp repair process, with best results using infrared laser 785 nm.

  17. Randomized controlled trial: Comparative efficacy for the treatment of facial telangiectasias with 532 nm versus 940 nm diode laser.

    PubMed

    Tierney, Emily; Hanke, C William

    2009-10-01

    While the 532 nm wavelength has been demonstrated to be effective for facial telangiectasias, 940 nm is a novel wavelength which has only been reported in case reports. While both the 532 and 940 nm wavelengths are effective for facial telangiectasias, we lack evidence to support whether one wavelength is superior. Randomized, blinded split-faced trial for the 532 and 940 nm diode laser wavelengths. Side effects of erythema, crusting, swelling, and blistering (0-5 scale, 0 = not present, 1 = trace, 5 = severe) were assessed. Prior to treatment and at 2 months after a series of two treatments, telangiectasias were assessed (1-10 scale, 1 = focal telangiectasias, 10 = diffuse telangiectasias). Assessment of the degree of improvement in facial telangiectasias was performed by two blinded non-treating physician evaluators from patient photographs. A total of 24 facial anatomic sites were treated with the 532 and 940 nm wavelengths. Presence and severity of side effects of erythema, crusting, swelling, blistering (0-5 scale, 0 = not present, 1 = trace, 5 = severe) were assessed. Pain associated with the laser treatment was rated as significantly less for the 940 nm wavelength relative to the 532 nm wavelength. Erythema post-treatment was significantly less with 940 nm relative to 532 nm. Significant crusting and swelling were only reported with the 532 nm wavelength. The mean percentage improvement with the 940 nm wavelength (63.0%) was greater than that achieved with the 532 nm wavelength (47.8%) (P<0.05). On photographic evaluation, 940 nm was significantly more efficacious for larger caliber vessels than 532 nm. Both wavelengths were equally efficacious for smaller caliber vessels. While both 532 and 940 nm diode laser produced significant improvement in facial telangiectasias, greater efficacy was found with 940 nm as well as a significantly more tolerable side effect profile. Lasers Surg. Med. 41:555-562, 2009. (c) 2009 Wiley-Liss, Inc.

  18. Fiber-laser pumped actively Q-switched Er:LuYAG laser at 1648 nm

    NASA Astrophysics Data System (ADS)

    Yang, X. F.; Wang, Y.; Zhao, T.; Zhu, H. Y.; Shen, D. Y.

    2016-02-01

    We demonstrated an acousto-optic Q-switched 1648 nm Er:LuYAG laser resonantly pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. Stable Q-switching operation was obtained with the pulse repetition rate (PRR) varying from 200 Hz to 10 kHz. At PRR of 200 Hz, the laser yielded Q-switched pulses with 3.3 mJ pulse energy and 65 ns pulse duration, corresponding to a peak power of 50.7 kW for 10.4 W of incident pump power.

  19. Study on the Pr:KYF ultraviolet laser at 305 nm pumped by blue laser

    NASA Astrophysics Data System (ADS)

    Ni, Tian-yi; Li, Yong-liang; Zhang, Tian-yi; Ruan, Ren-qiu

    2012-09-01

    An all-solid-state Pr:KY3F10 (Pr:KYF) laser pumped by blue laser (471 nm) has been demonstrated. With the incident pump power of 2.6 W, the maximum output power at 610 nm is 213 mW. Moreover, the intracavity second-harmonic generation (SHG) is also achieved with the maximum ultraviolet (UV) power at 305 nm of 11 mW by using a β-BaB2O4 (BBO) nonlinear crystal.

  20. Comparison of glass processing using high-repetition femtosecond (800 nm) and UV (255 nm) nanosecond pulsed lasers

    NASA Astrophysics Data System (ADS)

    Karnakis, Dimitris M.; Knowles, Martyn R. H.; Alty, Kevin T.; Schlaf, Martin; Snelling, Howard V.

    2005-01-01

    Laser processing of glass is of significant commercial interest for microfabrication of "lab-on-a-chip" microfluidic devices. High repetition rate pulsed lasers have been investigated and provide adequate processing speeds but suffer from the inherent risk of laser-induced microcracking and other collateral damage induced in the glass. In this paper we present a comparative study between nanosecond deep UV (255nm) frequency doubled copper laser and femtosecond Ti:Sapphire (800nm) regenerative amplifier laser machining of borosilicate glass. Microchannel scribing and high aspect ratio hole drilling is demonstrated in thick glass using direct writing and mask projection techniques. The resulting material structure geometries have been examined using SEM microscopy and white light interferometry. The feasibility of glass laser machining and the significance of each laser type for this application are discussed.

  1. Emission properties and CW laser operation of Pr:YLF in the 910 nm spectral range.

    PubMed

    Cai, Z P; Qu, B; Cheng, Y J; Luo, S Y; Xu, B; Xu, H Y; Luo, Z Q; Camy, P; Doualan, J L; Moncorgé, R

    2014-12-29

    The polarized emission spectra for the 3P01G4 emission transition of the Pr3+ ion around 910 nm in the Pr3+:LiYF4 (Pr:YLF) laser crystal were registered and calibrated in unit of cross sections for the first time. Continuous-wave (CW) laser operation is demonstrated at 915 nm in π polarization by pumping the crystal with an optically pumped semiconductor laser (OPSL) at 479.2 nm. An output power of 218 mW is thus obtained with a laser slope efficiency of about 24% for an output coupler (OC) transmission of 1.9%. CW laser operation is also demonstrated at 907 nm in σ polarization by using a thin plate oriented at Brewster angle. An output power of about 89 mW with a slope efficiency of about 10% is then obtained for an OC transmission of 0.8%.The round-trip cavity losses are estimated for different experimental cavity configurations to be about 1% and the typical beam quality M2 factors measured in the transverse x and y directions are found equal to about 1.07 and 1.04, respectively. Finally, we also report on a double laser wavelength operation by using an OC with a transmission of about 0.05%, such effect resulting from joint-etalon effects inside the cavity.

  2. Mechanistic comparison of blood undergoing laser photocoagulation at 532 and 1,064 nm.

    PubMed

    Black, John F; Wade, Norman; Barton, Jennifer Kehlet

    2005-02-01

    We seek to compare and contrast the mechanisms of blood photocoagulation under 532 and 1,064 nm laser irradiation in vitro in order to better understand the in vivo observations. We also seek to validate a finite element model (FEM) developed to study the thermodynamics of coagulation. We study the photocoagulation of whole blood in vitro at 532 and 1,064 nm using time-domain spectroscopic and optical coherence tomography (OCT)-based imaging techniques. We model the coagulation using an FEM program that includes the latent heat of vaporization (LHV) of water, consideration of the pulse shape of the laser, and the bathochromic shift in the hemoglobin absorption spectrum. We find significant similarities in the spectroscopic, chemical, and structural changes occurring in hemoglobin and in the blood matrix during photocoagulation despite the very large difference in the absorption coefficients. The more uniform temperature profile developed by the deeper-penetrating 1,064 nm laser allows us to resolve the structural phase transition in the red blood cells (going from biconcave disc to spherocyte) and the chemical transition creating met-hemoglobin. We find that the RBC morphology transition happens first, and that the met-Hb transition happens at a much higher temperature ( > 90 degrees C) than is found in slow bath heating. The FEM analysis with the LHV constraint and bathochromic shift predicts accurately the imaging results in both cases, and can be used to show that at 1,064 nm there is the potential for a runaway increase in absorption during the laser pulse. Photothermally mediated processes dominate the in vitro coagulation dynamics in both regimes despite the difference in absorption coefficients. There is a significant risk under 1,064 nm irradiation of vascular lesions in vivo that the dynamic optical properties of blood will cause runaway absorption and heating. This may in turn explain some recent results at this wavelength where full-thickness burns

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  4. Variation of cell spreading on TiO2 film modified by 775 nm and 388 nm femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Tsukamoto, M.; Shinonaga, T.; Sato, Y.; Chen, P.; Nagai, A.; Hanawa, T.

    2014-03-01

    Titanium (Ti) is one of the most used biomaterials in metals. However, Ti is typically artificial materials. Thus, it is necessary for improving the biocompatibility of Ti. Recently, coating of the titanium dioxides (TiO2) film on Ti plate has been proposed to improve biocompatibility of Ti. We have developed coating method of the film on Ti plate with an aerosol beam. Periodic structures formation on biomaterials was also a useful method for improving the biocompatibility. Direction of cell spreading might be controlled along the grooves of periodic microstructures. In our previous study, periodic nanostructures were formed on the film by femtosecond laser irradiation at fundamental wave (775 nm). Period of the periodic nanostructures was about 230 nm. In cell test, cell spreading along the grooves of the periodic nanostructures was observed although it was not done for the film without the periodic nanostructures. Then, influence of the period of the periodic nanostructures on cell spreading has not been investigated yet. The period might be changed by changing the laser wavelength. In this study, the periodic nanostructures were created on the film with femtosecond laser at 775nm and 388 nm, respectively. After cell test, cell spreading along the grooves of the periodic nanostructures was observed on 775 nm and 388nm laser irradiated areas. Distribution of direction of cell spreading on laser irradiated area was also examined. These results suggested that controlling the cell spreading on periodic nanostructures with period of 230 nm was better than that with period of 130 nm.

  5. 1125-nm quantum dot laser for tonsil thermal therapy

    NASA Astrophysics Data System (ADS)

    McMillan, Kathleen

    2011-03-01

    Thermal therapy has the potential to provide a nonexcisional alternative to tonsillectomy. Clinical implementation requires that the lymphoid tissue of tonsils is heated homogeneously to produce an amount of primary thermal injury that corresponds to gradual postoperative tonsil shrinkage, with minimal risk of damage to underlying critical blood vessels. Optical constants are derived for tonsils from tissue components and used to calculate the depth of 1/e of irradiance. The 1125 nm wavelength is shown to correspond to both deep penetration and minimal absorption by blood. A probe for tonsil thermal therapy that comprises two opposing light emitting, temperature controlled surfaces is described. For ex vivo characterization of tonsil heating, a prototype 1125 nm diode laser is used in an experimental apparatus that splits the laser output into two components, and delivers the radiation to sapphire contact window surfaces of two temperature controlled cells arranged to irradiate human tonsil specimens from opposing directions. Temperatures are measured with thermocouple microprobes at located points within the tissue during and after irradiation. Primary thermal damage corresponding to the recorded thermal histories are calculated from Arrhenius parameters for human tonsils. Results indicate homogeneous heating to temperatures corresponding to the threshold of thermal injury and above can be achieved in advantageously short irradiation times.

  6. 1550-nm nonablative laser resurfacing for facial surgical scars.

    PubMed

    Pham, Annette M; Greene, Ryan M; Woolery-Lloyd, Heather; Kaufman, Joely; Grunebaum, Lisa D

    2011-01-01

    To investigate the efficacy of 1550-nm (Fraxel SR1500 RE:Store; Solta Medical, Hayward, California) nonablative laser treatment of facial surgical scars. In this prospective clinical study, a volunteer sample of 13 adults with Fitzpatrick skin types I to III and facial surgical scars with a postoperative duration longer than 6 months were enrolled. Subjects were treated once every 4 weeks for a total of 4 treatments. Initial settings for the 1550-nm nonablative laser were at energy level 40 mJ and treatment level 4 and were subsequently increased on each visit according to the patients' tolerance level. Using a previously validated Patient and Observer Scar Assessment Scale (POSAS), the study subject and an independent evaluator completed assessments of the scar at each visit. According to the Friedman test on ratings across all occasions after the first treatment to the last evaluation, there was a statistically significant improvement in the patient's assessment of the color, stiffness, thickness, and irregularity of the scar but not for pain or itching. For the observer's ratings, there was a statistically significant improvement in pigmentation, thickness, relief, and pliability but not for vascularization. Preliminary data suggest improved aesthetic results, demonstrating the potential use of fractional photothermolysis as a scar revision technique. Future studies with a longer follow-up period could elucidate the role of fractional photothermolysis in more permanent scar improvements.

  7. 976-nm passively mode-locked ytterbium-doped fiber laser core-pumped by 915-nm semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhou, Yue

    2016-11-01

    In this paper, we demonstrate an all-normal dispersion (ANDi) femtosecond YDFL. The laser operates around 976 nm via single-clad single-mode core-pumped method, which could enhance the slope efficiency up to 19% compared to that of 14% via double-clad multi-mode pumped method. The pulse repetition rate is 44.3 MHz, and pulse energy is approximately 1 nJ. Through external cavity pulse compression by a pair of gratings, the pulse duration can be compressed to 250 fs, nearly transform-limited.

  8. Effects of 810 nm laser on mouse primary cortical neurons

    NASA Astrophysics Data System (ADS)

    Kharkwal, Gitika B.; Sharma, Sulbha K.; Huang, Ying-Ying; De Taboada, Luis; McCarthy, Thomas; Hamblin, Michael R.

    2011-03-01

    In the past four decades numerous studies have reported the efficacy of low level light (laser) therapy (LLLT) as a treatment for diverse diseases and injuries. Recent studies have shown that LLLT can biomodulate processes in the central nervous system and has been extensively studied as a stroke treatment. However there is still a lack of knowledge on the effects of LLLT at the cellular level in neurons. The present study aimed to study the effect of 810 nm laser on several cellular processes in primary cortical neurons cultured from mouse embryonic brains. Neurons were irradiated with light dose of 0.03, 0.3, 3, 10 and 30 J/cm2 and intracellular levels of reactive oxygen species, nitric oxide and calcium were measured. The changes in mitochondrial function in response to light were studied in terms of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP). Light induced a significant increase in calcium, ATP and MMP at lower fluences and a decrease at higher fluence. ROS was induced significantly by light at all light doses. Nitric oxide levels also showed an increase on treatment with light. The results of the present study suggest that LLLT at lower fluences is capable of inducing mediators of cell signaling process which in turn may be responsible for the biomodulatory effects of the low level laser. At higher fluences beneficial mediators are reduced but potentially harmful mediators are increased thus offering an explanation for the biphasic dose response.

  9. Portable 543 nm length standard and magnetic-induced zero-crossing shift on length standard transition

    SciTech Connect

    Cheng, W.-Y.; Hu, C.Y.; Shy, J.-T.

    2005-05-15

    This study reports on the development of a portable iodine-stabilized 543 nm (green) length-standard laser, which is low cost and robust. All the needed optics and electronics were integrated into one box which measured 36 cm in length, 30 cm in width, and 15 cm in height. Simple circuits for third harmonic locking are presented and the laser's frequency instability could be as small as 2x10{sup -12}, normalized to one hertz bandwidth. The influence of the magnetic field to the locking point of the 543 nm length-standard transitions was investigated.

  10. Coherence Measurements of a Transient 14.7 nm X-ray Laser

    SciTech Connect

    Remond, C; Dunn, J; Delmotte, F; Nilsen, J; Hubert, S; Ravet, M; Shlyaptsev, V; Zeitoun, P; Hunter, J; Vanbostal, L; Jacquemot, S; Smith, R; Fajardo, M; Lewis, C; Marmoret, R

    2003-11-25

    We present the longitudinal coherence measurement of the transient inversion collisional x-ray laser for the first time. The Ni-like Pd x-ray laser at 14.68 nm is generated by the LLNL COMET laser facility and is operating in the gain-saturated regime. Interference fringes are produced using a Michelson interferometer setup in which a thin multilayer-coated membrane is used as a beam splitter. The longitudinal coherence length for the picosecond duration 4d{sup 1}S{sub 0} {yields} 4p{sup 1}P{sub 1} lasing transition is determined to be {approx}400 {micro}m (1/e HW) by adjusting the length of one interferometer arm and measuring the resultant variation in fringe visibility. This is four times improved coherence than previous measurements on quasi-steady state schemes largely as a result of the narrower line profile in the lower temperature plasma. The inferred gain-narrowed linewidth of {approx}0.29 pm is also substantially narrower than previous measurements on quasi-steady state x-ray laser schemes. This study shows that the coherence of the x-ray laser beam can be improved by changing the laser pumping conditions. The x-ray laser is operating at 4 - 5 times the transform-limited pulse.

  11. Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching.

    PubMed

    Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi Kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad; Chiniforush, Nasim

    2016-12-30

    Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results.

  12. Note: deep ultraviolet Raman spectrograph with the laser excitation line down to 177.3 nm and its application.

    PubMed

    Jin, Shaoqing; Fan, Fengtao; Guo, Meiling; Zhang, Ying; Feng, Zhaochi; Li, Can

    2014-04-01

    Deep UV Raman spectrograph with the laser excitation line down to 177.3 nm was developed in this laboratory. An ellipsoidal mirror and a dispersed-subtractive triple monochromator were used to collect and disperse Raman light, respectively. The triple monochromator was arranged in a triangular configuration with only six mirrors used. 177.3 nm laser excited Raman spectrum with cut-off wavenumber down to 200 cm(-1) and spectral resolution of 8.0 cm(-1) can be obtained under the condition of high purity N2 purging. With the C-C σ bond in Teflon selectively excited by the 177.3 nm laser, resonance Raman spectrum of Teflon with good quality was recorded on the home-built instrument and the σ-σ(*) transition of C-C bond was studied. The result demonstrates that deep UV Raman spectrograph is powerful for studying the systems with electronic transition located in the deep UV region.

  13. Note: Deep ultraviolet Raman spectrograph with the laser excitation line down to 177.3 nm and its application

    NASA Astrophysics Data System (ADS)

    Jin, Shaoqing; Fan, Fengtao; Guo, Meiling; Zhang, Ying; Feng, Zhaochi; Li, Can

    2014-04-01

    Deep UV Raman spectrograph with the laser excitation line down to 177.3 nm was developed in this laboratory. An ellipsoidal mirror and a dispersed-subtractive triple monochromator were used to collect and disperse Raman light, respectively. The triple monochromator was arranged in a triangular configuration with only six mirrors used. 177.3 nm laser excited Raman spectrum with cut-off wavenumber down to 200 cm-1 and spectral resolution of 8.0 cm-1 can be obtained under the condition of high purity N2 purging. With the C-C σ bond in Teflon selectively excited by the 177.3 nm laser, resonance Raman spectrum of Teflon with good quality was recorded on the home-built instrument and the σ-σ* transition of C-C bond was studied. The result demonstrates that deep UV Raman spectrograph is powerful for studying the systems with electronic transition located in the deep UV region.

  14. Temperature dependence of quasi-three level laser transition for long pulse Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Bidin, Noriah; Pourmand, Seyed Ebrahim; Sidi Ahmad, Muhamad Fakaruddin; Khrisnan, Ganesan; Mohd Taib, Nur Athirah; Nadia Adnan, Nurul; Bakhtiar, Hazri

    2013-02-01

    The influence of temperature and pumping energy on stimulated emission cross section and the laser output of quasi-three level laser transition are reported. Flashlamp is used to pump Nd:YAG laser rod. Distilled water is mixed with ethylene glycol to vary the temperature of the cooling system between -30 and 60 °C. The capacitor voltage of flashlamp driver is verified to manipulate the input energy within the range of 10-70 J. The line of interest in quasi-three level laser comprised of 938.5 and 946 nm. The stimulated emission cross section of both lines is found to be inversely proportional to the temperature but directly proportional to the input energy. This is attributed from thermal broadening effect. The changes of stimulated emission cross section and the output laser with respect to the temperature and input energy on line 946 nm are realized to be more dominant in comparison to 938.5 nm.

  15. Healing of surgical wounds made with lambda970-nm diode laser associated or not with laser phototherapy (lambda655 nm) or polarized light (lambda400-2000 nm).

    PubMed

    Medeiros, Juliana L; Nicolau, Renata A; Nicola, Ester M D; dos Santos, Jean N; Pinheiro, Antonio L B

    2010-08-01

    The aim of this study was to analyze the effect of two phototherapies, laser and polarized light, on diode laser (970lambda nm) wounds. Lasers have been used in surgery, and some wavelengths may cause thermal damage to the tissue and affect healing. Several studies have shown that some wavelengths are effective in improving healing. Coherent and noncoherent light have been successfully used on the modulation of biological phenomena of several origins. Thirty-one Wistar rats were divided into 3 groups (GI to GIII). A 20-mm x 2-mm wound was created on the dorsum of each animal with a diode laser (Sirolaser, Sirona, Bensheim, Germany). Group GI acted as control. On GII, laser light (lambda655 nm, 30 mW, phi approximately 3 mm, 12 J/cm(2)) was used and on GIII illumination with polarized light (lambda400-2000 nm, 40 mW, phi approximately 5.5 cm, 12 J/cm(2)) was used, every other day (GII) or daily (GIII) for 7 days. The animals were killed at 0, 7, and 14 days after surgery. Specimens were taken, routinely processed, stained and imunnomarked [HE (hematoxylin-eosin), sirius red, alpha-smooth muscle actin (SMA)], and underwent histological analysis. GII showed better response at day 14 when re-epithelialization was in a more advanced stage. The number of myofibroblasts was significantly different over the healing time (7 to 14 days); this number was smaller than that observed on G1. On GIII at day 7, the number of myofibroblasts was significantly higher than for GII. At day 14, a more pronounced deposition of collagen matrix was also seen, and inflammation was discrete and more advanced for GIII. The results of the present study showed that the effect of the use of laser light was more evident at early stages of healing and that the use of polarized light improved the resolution of the inflammatory reaction, increased the deposition of collagen, increased the number of myofibroblasts, and quickened re-epithelialization during the experimental time.

  16. Wavelength-multiplexed pumping with 478- and 520-nm indium gallium nitride laser diodes for Ti:sapphire laser.

    PubMed

    Sawada, Ryota; Tanaka, Hiroki; Sugiyama, Naoto; Kannari, Fumihiko

    2017-02-20

    We experimentally reveal the pump-induced loss in a Ti:sapphire laser crystal with 451-nm indium gallium nitride (InGaN) laser diode pumping and show that 478-nm pumping can reduce such loss. The influence of the pump-induced loss at 451-nm pumping is significant even for a crystal that exhibits higher effective figure-of-merit and excellent laser performance at 520-nm pumping. We demonstrate the power scaling of a Ti:sapphire laser by combining 478- and 520-nm InGaN laser diodes and obtain CW output power of 593 mW.

  17. Diode laser pumped blue-light source at 473 nm using intracavity frequency doubling of a 946 nm Nd:YAG laser

    SciTech Connect

    Risk, W.P.; Pon, R.; Lenth, W.

    1989-04-24

    Using intracavity frequency doubling of a diode laser pumped 946 nm Nd:YAG laser, 3.1 mW of blue output power at 473 nm was obtained. Angle-tuned, type-I frequency doubling in potassium niobate was employed, and both the KNbO/sub 3/ and Nd:YAG crystals were used at room temperature.

  18. TO packaged 650nm red semiconductor laser with transparent window

    NASA Astrophysics Data System (ADS)

    Xia, Wei; Zhu, Zhen; Li, Peixu; Su, Jian; Zhang, Xin; Xu, Xiangang

    2016-11-01

    Highly uniform solid-phase Zn-diffusion technique was developed to fabricate transparent windows for 650 nm red laser diodes (LDs). The maximum output power was up to 120 mW, which is three times higher than that for LDs without window structure. The LDs showed excellent thermal characteristics and aging reliability with TO-can package. The characteristic temperature was estimated to be 85 K in the temperature range of 25 65 °C. The LDs showed stable operation of 10 mW at a high temperature of 75 °C. After aging test of 2000 h, the elevated operation current was less than 3%, compared to the initial value. The predicted life time was over 10000 h for 10 mW operation at 75 °C.

  19. A comparison of corneal cellular responses after 213-nm compared with 193-nm laser photorefractive keratectomy in rabbits.

    PubMed

    Sanders, Talia; Pujara, Tarak; Camelo, Serge; Lai, Ching Tat; Van Saarloos, Paul; Beazley, Lyn; Rodger, Jennifer

    2009-05-01

    Corneal refractive surgery is typically performed using a 193-nm excimer laser. However, a recently developed 213-nm solid-state (5th harmonic) Nd:YAG laser presents some practical and user safety advantages, although the biological impact of using this wavelength remains poorly characterized. Here, we provide in vivo and in vitro comparisons of the corneal cellular outcomes after irradiation with 213 and 193 nm wavelengths. New Zealand White rabbits underwent photorefractive keratectomy with -5 diopters and a 6.5-mm optical zone and studied at time points up to 1 year. The development of haze was examined ophthalmologically and by detecting myofibroblasts immunohistochemically. Cell death was quantified using a terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay, and the number of stromal keratocytes undergoing apoptosis estimated histologically. Superoxide dismutase activity was estimated in vitro by enzyme-linked immunosorbent assay in irradiated rabbit corneal keratocytes. Our results demonstrate subtle differences in the cellular outcomes after irradiation with 213- and 193-nm lasers, despite similar degrees of corneal haze developing in both treatment groups. In vivo, the 213-nm laser results in more stable stromal cell numbers, implying a more predictable ablation outcome. In vitro, higher levels of superoxide dismutase in corneal keratocytes irradiated with 213 nm compared with 193 nm wavelengths suggest a better endogenous protection against free radicals induced by laser surgery. The more favorable cellular responses after irradiation with 213 nm compared with 193 nm wavelengths are consistent with good clinical outcomes previously reported. Ablation with a 213 nm wavelength may result in better wound healing, leading to a more reliable correction of refractive errors.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. Magnetoelastically induced magnetic anisotropy transition in [CoO5nm/CoPt7nm]5 multilayer films

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Harumoto, Takashi; Sannomiya, Takumi; Muraishi, Shinji; Nakamura, Yoshio; Shi, Ji

    2016-06-01

    The magnetic anisotropy transition of [CoO5nm/CoPt7nm]5 multilayer film with respect to post-annealing has been studied systematically. It undergoes a smooth transition from longitudinal magnetic anisotropy (LMA) to perpendicular magnetic anisotropy (PMA) upon annealing and returns backward to LMA at high temperature of 550 °C. The strongest PMA of [CoO5nm/CoPt7nm]5 is achieved after post-annealing at 300 °C and the tolerable post-annealing temperature with strong PMA is up to 400 °C, which indicates this multilayer film could be a potential candidate for the PMA application at middle-high-temperature-region between 300 °C and 400 °C. The mechanism responsible for the transition of magnetic anisotropy has been investigated by analyzing CoO/CoPt interface and CoPt layer internal stress. It is found the effective PMA energy is proportional to the in-plane tensile stress of CoPt layer but is inversely proportional to the roughness of CoO/CoPt interface. Finally, by means of low temperature experiment we demonstrate the magnetic anisotropy transition observed in [CoO5nm/CoPt7nm]5 multilayer film is mainly attributed to the change of CoPt layer in-plane tensile stress.

  2. Toward Ultraintense Compact RBS Pump for Recombination 3.4 nm Laser via OFI

    NASA Astrophysics Data System (ADS)

    Suckewer, S.; Ren, J.; Li, S.; Lou, Y.; Morozov, A.; Turnbull, D.; Avitzour, Y.

    In our presentation we overview progress we made in developing a new ultrashort and ultraintensive laser system based on Raman backscattering (RBS) amplifier /compressor from time of 10th XRL Conference in Berlin to present time of 11th XRL Conference in Belfast. One of the main objectives of RBS laser system development is to use it for pumping of recombination X-ray laser in transition to ground state of CVI ions at 3.4 nm. Using elaborate computer code the processes of Optical Field Ionization, electron energy distribution, and recombination were calculated. It was shown that in very earlier stage of recombination, when electron energy distribution is strongly non-Maxwellian, high gain in transition from the first excited level n=2 to ground level m=1 can be generated. Adding large amount of hydrogen gas into initial gas containing carbon atoms (e.g. methane, CH4) the calculated gain has reached values up to 150-200 cm-2 Taking into account this very encouraging result, we have proceed with arrangement of experimental setup. We will present the observation of plasma channels and measurements of electron density distribution required for generation of gain at 3.4 nm.

  3. 1700 nm and 1800 nm band tunable thulium doped mode-locked fiber lasers.

    PubMed

    Emami, Siamak Dawazdah; Dashtabi, Mahdi Mozdoor; Lee, Hui Jing; Arabanian, Atoosa Sadat; Rashid, Hairul Azhar Abdul

    2017-10-06

    This paper presents short wavelength operation of tunable thulium-doped mode-locked lasers with sweep ranges of 1702 to 1764 nm and 1788 to 1831 nm. This operation is realized by a combination of the partial amplified spontaneous emission suppression method, the bidirectional pumping mechanism and the nonlinear polarization rotation (NPR) technique. Lasing at emission bands lower than the 1800 nm wavelength in thulium-doped fiber lasers is achieved using mode confinement loss in a specially designed photonic crystal fiber (PCF). The enlargement of the first outer ring air holes around the core region of the PCF attenuates emissions above the cut-off wavelength and dominates the active region. This amplified spontaneous emission (ASE) suppression using our presented PCF is applied to a mode-locked laser cavity and is demonstrated to be a simple and compact solution to widely tunable all-fiber lasers.

  4. Holmium:YAG (lambda = 2,120 nm) versus thulium fiber (lambda = 1,908 nm) laser lithotripsy.

    PubMed

    Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

    2010-03-01

    The holmium:YAG laser is currently the most common laser lithotripter. However, recent experimental studies have demonstrated that the thulium fiber laser is also capable of vaporizing urinary stones. The high-temperature water absorption coefficient for the thulium wavelength (mu(a) = 160 cm(-1) at lambda = 1,908 nm) is significantly higher than for the holmium wavelength (mu(a) = 28 cm(-1) at lambda = 2,120 nm). We hypothesize that this should translate into more efficient laser lithotripsy using the thulium fiber laser. This study directly compares stone vaporization rates for holmium and thulium fiber lasers. Holmium laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 microseconds pulse duration was delivered through a 100-microm-core silica fiber to human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Thulium fiber laser radiation pulsed at 10 Hz with 70 mJ pulse energy and 1-millisecond pulse duration was also delivered through a 100-microm fiber for the same sets of 10 stones each. For the same number of pulses and total energy (126 J) delivered to each stone, the mass loss averaged 2.4+/-0.6 mg (UA) and 0.7+/-0.2 mg (COM) for the holmium laser and 12.6+/-2.5 mg (UA) and 6.8+/-1.7 (COM) for the thulium fiber laser. UA and COM stone vaporization rates for the thulium fiber laser averaged 5-10 times higher than for the holmium laser at 70 mJ pulse energies. With further development, the thulium fiber laser may represent an alternative to the conventional holmium laser for more efficient laser lithotripsy.

  5. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    PubMed

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  6. Endovenous treatment of the great saphenous vein using a 1,320 nm Nd:YAG laser causes fewer side effects than using a 940 nm diode laser.

    PubMed

    Proebstle, Thomas M; Moehler, Thomas; Gül, Doendue; Herdemann, Sylvia

    2005-12-01

    Limited data are available about treatment-related side effects with respect to laser wavelength in endovenous laser treatment (ELT) of the great saphenous vein (GSV). To compare the results and side effects of a 940 nm diode and a 1,320 nm neodymium:yttium-aluminum-garnet (Nd:YAG) laser. Three patient cohorts (A, B, and C) received ELT of the GSV using a 940 nm diode laser at 15 W (group A) or 30 W (group B) or using a 1,320 nm laser at 8 W (group C). In all cases, energy was administered continuously with constant pullback of the laser fiber under perivenous tumescent local anesthesia. The GSVs of group A (n = 113), group B (n = 136), and group C (n = 33) received ELT. An average linear endovenous energy density of 24, 63, and 62 J/cm and an average endovenous fluence equivalent of 12, 30, and 33 J/cm2 were administered to the vein. Occlusion rates were 95% (group A), 100% (group B), and 100% (group C) at day 1 after ELT and 90.3% (group A), 100% (group B), and 97% (group C) at 3 months after ELT. With the 1,320 nm laser ELT (group C), treatment-related pain (50%) and the need for analgesics (36%) were significantly reduced (p < .005) in comparison with treatment-related pain (81%) and the need for analgesics (67%) after the 30 W 940 nm laser ELT (group B). Ecchymosis was also significantly reduced (p < .05) in group C (1,320 nm) compared with group B (30 W, 940 nm). ELT of the GSV using a 1,320 nm Nd:YAG laser causes fewer side effects compared with 940 nm diode laser ELT.

  7. Laser ablation of enamel and composite using 355-nm laser pulses: influence of fluoride and laser treatment on adhesion

    NASA Astrophysics Data System (ADS)

    Larson, Michael D.; Gardner, Andrew K.; Staninec, Michal; Fried, Daniel

    2006-02-01

    Previous studies have demonstrated that Q-switched 355-nm laser pulses can be used to remove composite sealants and restorations from tooth surfaces without significant damage to sound tooth surfaces and have also shown that 355-nm lasers pulses can also be used to selectively etch the interprismatic protein of enamel to increase the effectiveness of topical fluoride for inhibiting decay and increase the bond strength to restorative materials without acid-etching. The first aim of this study was to test the hypothesis that topical fluoride can be applied after laser irradiation before composite resin placement without significantly reducing the bond-strength. The second aim was to test the hypothesis that thermal damage to existing composite due to laser irradiation does not compromise the adhesion of newly applied composite. There was a slight but significant reduction in the magnitude of the shear-bond strength of laser-treated surfaces with and without fluoride application. There was no significant difference in the magnitude of the bond strength between laser irradiated and non-laser irradiated aged composite to newly applied composite. These results suggest that after composite removal with 355-nm laser pulses fluoride can be subsequently applied to inhibit secondary caries before placement of composite restorative materials and that 355-nm laser pulses can be used for the repair of existing restorations.

  8. Technique for cellular microsurgery using the 193-nm excimer laser.

    PubMed

    Palanker, D; Ohad, S; Lewis, A; Simon, A; Shenkar, J; Penchas, S; Laufer, N

    1991-01-01

    A new cell surgery technique has been developed to produce well-defined alterations in cells and tissue without detectable heating and/or other structural damage in the surroundings. The technique involves the use of an argon fluoride excimer laser, in the deep ultraviolet (UV) region of the spectrum at 193 nm, which is guided through a glass pipette filled with a positive air pressure. To demonstrate the method, holes were drilled in the zona pellucida of mouse oocytes. The diameter of the drilled hole was determined by the pipette tip size, and its depth by an energy emitted per pulse and number of pulses. Scanning electron microscopy of the drilled mouse oocytes showed uniform, round, well-circumscribed holes with sharp edges. Oocytes that had their zona pellucida drilled with this new method fertilized in vitro and developed to the blastocyst stage in a rate similar to that of control group. These results demonstrate the nonperturbing nature of this cold laser microsurgical procedure. In addition to the extension of our results for clinical in vitro fertilization purposes, such as enhancement of fertilization and embryo biopsy, there are wide-ranging possible uses of our method in fundamental and applied investigations that require submicron accuracy in cellular alteration.

  9. Structure, spectroscopic properties and laser performance of Nd:YNbO4 at 1066 nm

    NASA Astrophysics Data System (ADS)

    Ding, Shoujun; Peng, Fang; Zhang, Qingli; Luo, Jianqiao; Liu, Wenpeng; Sun, Dunlu; Dou, Renqin; Sun, Guihua

    2016-12-01

    We have demonstrated continuous wave (CW) laser operation of Nd:YNbO4 crystal at 1066 nm for the first time. A maximum output power of 1.12 W with the incident power of 5.0 W is successfully achieved corresponding to an optical-to-optical conversion efficiency of 22.4% and a slope efficiency of 24.0%. The large absorption cross section (8.7 × 10-20 cm2) and wide absorption band (6 nm) at around 808 nm indicates the good pumping efficiency by laser diodes (LD). The small emission cross section (29 × 10-20 cm2) and relative long lifetime of the 4F3/2 → 4I11/2 transition indicates good energy storage capacity of Nd:YNbO4. Moreover, the raw materials of Nd:YNbO4 are stable, thus, it can grow high-quality and large-size by Czochralski (CZ) method. Therefore the Nd:YNbO4 crystal is a potentially new laser material suitable for LD pumping.

  10. Half-Watt single frequency yellow 561 nm and yellow-green 553 nm DPSS lasers with record 19% optical conversion efficiency

    NASA Astrophysics Data System (ADS)

    Georges, Thierry; Chauzat, Corinne; Poivre, Aurélia

    2010-02-01

    Since the first introduction of DPSS lasers at 561 nm in 2004, the power level required by some biotechnical applications has always increased. Oxxius has contributed to fulfill the demand thanks to the introduction of the SLIM-561 100mW in 2008 and of the SLIM-561 200mW and 300mW in 2009. More recently, new dyes or nano-dots have required shorter wavelengths (such as 553 nm) and new applications such as Laser Doppler Velocimetry requiring both high power and single frequency operation have appeared. In this presentation, we demonstrate how to further increase the power. 553nm and 561 nm emission are obtained by frequency doubling the 1106 nm and 1123 nm lines of Nd:YAG. The latter transitions are significantly weaker than the 1064 nm line. As a consequence, any loss in the cavity significantly increases the laser threshold. Because of the perfect alignment of the crystal interfaces and the low divergence of the intracavity beam, monolithic cavities demonstrate significantly reduced round-trip losses compared to standard cavities. Consequently, laser threshold can be dramatically reduced and the nonlinear loss, responsible for the visible emission, can easily dominate the linear losses. We have taken standard monolithic cavities of our commercial SLIM-561 products and have increased the pumping power up to 2.8 W. Yellow and Yellow-green powers have not shown any sign of saturation and 0.5 W could be achieved at both wavelengths. This results in a record 18% pump to signal optical efficiency. We have checked that the emission remained single frequency whatever the pumping power.

  11. Application of COTS high-speed 980-nm pump laser diode and driver for free-space laser communication terminal

    NASA Astrophysics Data System (ADS)

    Chan, Eric Y.; Adams, Jeff C.; Saint Clair, Jonathan M.; Morrison, Kenneth A.; Sosa, Martin

    1999-06-01

    In our Photonics West 98 paper, we presented our study results on using commercially available 860 nm high power laser diodes and high-speed laser driver for free-space laser communication terminal application. We demonstrated the feasibility of a free space laser communication link using a junction-up 860 nm high power laser diode driven by a high current laser driver from Hytek Microsystems up to 622 Mb/s. Recent development in high speed InGaAs/GaAs strained layer quantum well (SLQW) laser at 980 nm has provided an additional design option for a laser communication terminal. The advantages of using the 980 nm laser are: (1) WDM market in the telecom industry has created a volume demand for the 980 nm pump lasers. The future cost of 980 nm lasers is expected to be lower due to the economy of scale. (2) In our previous publications, we have demonstrated CW operation of strained layer QW laser at temperature higher than 200 degree(s)C. There is a potential for this type of laser diode to operate in a much harsher and higher temperature environment, and (3) 980 nm pump laser has output power comparable to high power 860 nm laser diodes. In this paper, we will present the high data rate characteristics of a high-speed 980 nm (SLQW) pump laser. Using commercial-off-the-shelf laser drivers we will demonstrate the laser transmitter system characteristics from 622 Mb/s to 3 Gb/s. Detail experimental results on bit- error-rate measurement for a 980 nm device will be presented.

  12. Room-temperature diode-bar-pumped Nd:YAG laser at 946 nm

    SciTech Connect

    Clarkson, W.A.; Koch, R.; Hanna, D.C.

    1996-05-01

    Efficient, high-power operation of a diode-bar-pumped Nd:YAG laser on the quasi-three-level transition at 946 nm is reported. Longitudinal pumping of a simple folded cavity by a 20-W diode bar, with a two-mirror beam shaper used to reformat the bar{close_quote}s output, yields a continuous-wave output power at room temperature of {approximately}3W in a 1.5-times diffraction-limited beam for 13.6 W of incident pump power. The corresponding optical slope efficiency was approximately 33{percent}. {copyright} {ital 1996 Optical Society of America.}

  13. 32.8-nm X-ray laser produced in a krypton cluster jet

    SciTech Connect

    Ivanova, E P; Vinokhodov, A Yu

    2013-12-31

    We have interpreted the well-known experimental quantum yield data for a 32.8-nm X-ray laser operating at the 3d{sup 9}4d (J = 0) – 3d{sup 9}4p (J = 1) transition of Kr{sup 8+} with the use of gaseous krypton or a krypton cluster jet. Proceeding from our model we propose a novel scheme for the 32.8-nm laser produced in a krypton cluster jet. The quantum yield is shown to saturate for a plasma length of ∼300 μm, a krypton ion density n{sub Kr} ∼ (4 – 9) × 10{sup 19} cm{sup -3}, and an electron temperature Te ∼ 5000 eV. In this case, the energy conversion coefficient amounts to ∼5 × 10{sup -3} of the pump pulse energy. We propose the experimental setup for producing a highefficiency subpicosecond X-ray laser in a krypton cluster jet. (lasers)

  14. Q -switched laser at 912 nm using ground-state-depleted neodymium in yttrium orthosilicate

    SciTech Connect

    Beach, R.; Albrecht, G.; Solarz, R.; Krupke, W.; Comaskey, B.; Mitchell, S. ); Brandle, C.; Berkstresser, G. )

    1990-09-15

    A ground-state-depleted laser is demonstrated in the form of a {ital Q}-switched oscillator operating at 912 nm. By using Nd{sup 3+} as the active ion and Y{sub 2}SiO{sub 5} as the host material, the laser transition is from the lowest-lying Stark level of the Nd{sup 3+} {sup 4}{ital F}{sub 3/2} level to a Stark level 355 cm{sup {minus}1} above the lowest-lying one in the {sup 4}{ital I}{sub 9/2} manifold. The necessity of depleting the ground {sup 4}{ital I}{sub 9/2} manifold is evident for this level scheme as transparency requires a 10% inversion. To achieve the high excitation levels required for the efficient operation of this laser, bleach-wave pumping using an alexandrite laser at 745 nm has been employed. With KNbO{sub 3}, noncritical phase matching is possible at 140{degree} C using {ital d}{sub 32} and is demonstrated.

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

    PubMed Central

    Wollina, Uwe

    2016-01-01

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

  16. 1 W at 785 nm from a frequency-doubled wafer-fused semiconductor disk laser.

    PubMed

    Rantamäki, Antti; Rautiainen, Jussi; Lyytikäinen, Jari; Sirbu, Alexei; Mereuta, Alexandru; Kapon, Eli; Okhotnikov, Oleg G

    2012-04-09

    We demonstrate an optically pumped semiconductor disk laser operating at 1580 nm with 4.6 W of output power, which represents the highest output power reported from this type of laser. 1 W of output power at 785 nm with nearly diffraction-limited beam has been achieved from this laser through intracavity frequency doubling, which offers an attractive alternative to Ti:sapphire lasers and laser diodes in a number of applications, e.g., in spectroscopy, atomic cooling and biophotonics.

  17. Highly reliable, high-brightness 915nm laser diodes for fiber laser applications

    NASA Astrophysics Data System (ADS)

    Xu, Zuntu; Gao, Wei; Cheng, Lisen; Luo, Kejian; Shen, Kun; Mastrovito, Andre

    2008-02-01

    High brightness, high power, and highly reliable 915nm InAlGaAs laser diodes with optimized design are reported in this paper. The laser diodes exhibit excellent performance, such as, high slope efficiency, low threshold current, low voltage, etc., which make them suitable for high brightness operation. The aging test data shows no failures during aging test and more than 220,000 hours estimated lifetime for 90um emitter laser diodes at 8W CW operation. The aging test with the same emitter size at higher stress conditions showed sudden failure that corresponds to catastrophic optical damage (COD) on the facet. A novel large optical cavity (LOC) epi-structure with flat-top near field intensity distribution was developed. The maximum output power is up to 23W under CW testing condition at 25 °C, which is highest level achieved so far. The output power is limited by thermal roll over and there is no COD occurring. This data shows Axcel's technologies can further increase the brightness to over 110mW per micron for 915nm laser diodes. This type of laser diodes is essential for pumping fiber lasers to replace CO2 lasers for industry applications.

  18. Nd:YAG laser diode-pumped directly into the emitting level at 938 nm.

    PubMed

    Sangla, Damien; Balembois, François; Georges, Patrick

    2009-06-08

    We present the first demonstration of Nd:YAG laser pumped directly in band at 938 nm with a high-brightness fiber-coupled laser diode. Up to 6 W of CW laser emission at 1064 nm have been obtained under an absorbed pump power of 28 W at 938 nm. A comparison between 808 nm and 938 nm pumping, realized by thermal cartography, demonstrates the very low heat generation of in-band pumping. Numerical simulations were also implemented to study and discuss the laser performance of our system.

  19. High-efficiency fiber laser at 1018 nm using Yb-doped phosphosilicate fiber.

    PubMed

    Wang, Jianhua; Chen, Gui; Zhang, Lei; Hu, Jinmeng; Li, Jinyan; He, Bing; Chen, Jinbao; Gu, Xijia; Zhou, Jun; Feng, Yan

    2012-10-10

    A high-efficiency fiber laser at 1018 nm using homemade Yb-doped phosphosilicate fiber is demonstrated. The fiber shows blueshifted emission spectrum compared to Yb-doped aluminosilicate fiber, and is considered favorable for the short wavelength Yb-doped fiber laser. With a 7 m gain fiber, up to 22.8 W output at 1018 nm is achieved with an optical efficiency of 53%. The amplified spontaneous emission at 1030 nm is suppressed to 50 dB below the 1018 nm laser. This work shows that highly-efficient fiber laser at 1018 nm can be obtained with Yb-doped phosphosilicate fiber.

  20. Pd nanoparticles formation by femtosecond laser irradiation and the nonlinear optical properties at 532 nm using nanosecond laser pulses

    SciTech Connect

    Fan Guanghua; Qu Shiliang; Wang Qiang; Zhao Chongjun; Zhang Lei; Li Zhongguo

    2011-01-15

    Pd nanoparticles (NPs) were prepared by focused femtosecond laser irradiation of PdCl{sub 2} dissolved in ethanol. Transmission electron microscopy (TEM) analysis revealed that Pd NPs show certain crystalline microstructure, and the average diameter is 3.4 nm with narrow size distribution from 2.0 to 6.0 nm. The nonlinear optical absorption and refraction of Pd NPs solution were investigated with nanosecond laser pulses at 532 nm. The nonlinear absorption of Pd NPs is saturable at low intensity of 3.28x10{sup 11} W/m{sup 2} but it is changed to reverse saturable with the intensity increased to 7.96x10{sup 11} W/m{sup 2}, which accordingly indicates the nonlinear refraction is changed from self-defocusing to self-focusing. The transition of the nonlinear absorption with the increase in pulse intensity is analyzed by an empirical model which includes mostly saturable absorption (SA) and two-photon absorption (TPA). The intensity of saturable I{sub s} is obtained, along with TPA coefficient {beta}. SA and TPA are both originated from the interband transition between the d band and s-p conduction band. The SA possess less occupied density of states in the ground state and less unoccupied density of states in the excited state than that of TPA, so the TPA dominates the nonlinear absorption when the pulse intensity is high, leading to as-observed transition from SA to TPA. The refraction variation with increase in pulse intensity is attributed to the interband transition of electrons from d band to s-p conduction band in the Pd NPs.

  1. Electro-optically Q-switched dual-wavelength Nd:YLF laser emitting at 1047 nm and 1053 nm

    NASA Astrophysics Data System (ADS)

    Men, Shaojie; Liu, Zhaojun; Cong, Zhenhua; Li, Yongfu; Zhang, Xingyu

    2015-05-01

    A flash-lamp pumped electro-optically Q-switched dual-wavelength Nd:YLF laser is demonstrated. Two Nd:YLF crystals placed in two cavities are employed to generate orthogonally polarized 1047 nm and 1053 nm radiations, respectively. The two cavities are jointed together by a polarizer and share the same electro-optical Q-switch. Two narrow-band pass filters are used to block unexpected oscillations at the hold-off state of the electro-optical Q-switch. In this case, electro-optical Q-switching is able to operate successfully. With pulse synchronization realized, the maximum output energy of 66.2 mJ and 83.9 mJ are obtained for 1047 nm and 1053 nm lasers, respectively. Correspondingly, the minimum pulse width is both 17 ns for 1047 nm and 1053 nm lasers. Sum frequency generation is realized. This demonstrates the potential of this laser in difference-frequency generations to obtain terahertz wave.

  2. Endovenous laser ablation of varicose veins with the 1470-nm diode laser.

    PubMed

    Schwarz, Thomas; von Hodenberg, Eva; Furtwängler, Christian; Rastan, Aljoscha; Zeller, Thomas; Neumann, Franz-Josef

    2010-06-01

    Endovenous laser ablation (EVLA) is one of the most accepted treatment options for varicose veins. In previous studies conducted with a laser at 810 to 1320 nm, paresthesia, pain, and ecchymosis were common adverse effects. We hypothesized that a lower linear endovenous energy density (LEED), as used with 1470-nm diode laser fibers, would lead to a reduction in adverse events. We conducted a prospective, nonrandomized observational cohort study of 312 consecutively treated lower limbs legs in 286 patients. Of these, a bare laser fiber (ELVeS-plus kit) was used to treat 168 legs in 150 patients (group 1), and a radial fiber (ELVeS-radial kit) was used in 144 legs in 136 patients (group 2). Laser treatment was performed in the great saphenous vein. Follow-up for all patients was 3 months. The primary end point was the occurrence of ecchymosis and bruising. This was correlated to the reduced LEED needed with the 1470-nm diode laser. Laser fiber (odds ratio [OR], 22.3; 95% confidence interval [CI], 20.2-24.5) and body mass index (OR, 0.35; 95% CI, 0.15-0.55) were identified as independent parameters for LEED. In group 2 compared with group 1, LEED in the great saphenous vein could be reduced from 79.4 +/- 9.1 to 57.4 +/- 10 J/cm (P < .0001). LEED was an independent parameter for skin bleeding (OR, 1.04; 95% CI, 1.017-1.058). Ecchymosis and bruising were significantly less frequent in group 2 than in group 1 (P < .0001). The need for analgesia was low, with 103.08 +/- 15.34 mg diclofenac-sodium in group 1 vs 82.08 +/- 18.86 mg in group 2 (P < .04). Occlusion with elimination of reflux was achieved in 100% of group 1 and group 2 (P < 1). No recanalization occurred at follow-up. Endovenous laser treatment of varicose veins in the great saphenous vein with the 1470-nm diode laser is safe and highly effective. The lower energy level needed using the radial laser fiber significantly minimized adverse effects compared with the bare laser fiber. Copyright (c) 2010 Society for

  3. Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm.

    PubMed

    Lee, Hee Chul; Byeon, Sung Ug; Lukashev, Alexei

    2012-04-01

    We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.

  4. Pulsed-periodic laser on RM helium and strontium transitions

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.; Polunin, Yu. P.; Reimer, I. V.; Khokhryakov, I. V.

    2008-01-01

    Conditions of generation of a running excitation wave in the active medium of gas lasers and efficiency of the running wave application for pumping of the active medium are considered by the example of a strontium vapor laser. It is demonstrated that the running excitation wave is generated directly in the active laser medium and is supported by the energy stored in the capacitive component of the impedance of a gas-discharge tube. Generation on the self-limited (21P1-21S0) transition of the helium atom at λ = 2058 nm and simultaneous generation on RM transitions of the strontium ion and strontium and helium atoms and on a number of neon atom transitions is first excited.

  5. Vacuum ultraviolet argon excimer laser at 126 nm excited by a high intensity laser

    NASA Astrophysics Data System (ADS)

    Kaku, Masanori; Harano, Shinya; Katto, Masahito; Kubodera, Shoichi

    2010-09-01

    We have observed the optical amplification of the Ar2* excimer at 126 nm pumped by optical-field-induced ionization (OFI) caused by an infrared high-intensity laser. We have evaluated similar small signal gain coefficients of approximately 1.0 cm-1 in two different experiments, where OFI Ar plasmas as gain media were produced in free space filled with Ar and inside an Ar-filled hollow fiber. This indicates that the function of a hollow fiber was to guide the infrared excitation laser and VUV Ar2* emissions, and not to regulate the OFI plasma. Despite the gain coefficient value at 126 nm, the laser oscillation has not been observed. This was limited by the optical quality of available state-of-the-art vacuum ultraviolet optics.

  6. Direct writing of 150 nm gratings and squares on ZnO crystal in water by using 800 nm femtosecond laser.

    PubMed

    Liu, Jukun; Jia, Tianqing; Zhou, Kan; Feng, Donghai; Zhang, Shian; Zhang, Hongxin; Jia, Xin; Sun, Zhenrong; Qiu, Jianrong

    2014-12-29

    We present a controllable fabrication of nanogratings and nanosquares on the surface of ZnO crystal in water based on femtosecond laser-induced periodic surface structures (LIPSS). The formation of nanogrooves depends on both laser fluence and writing speed. A single groove with width less than 40 nm and double grooves with distance of 150 nm have been produced by manipulating 800 nm femtosecond laser fluence. Nanogratings with period of 150 nm, 300 nm and 1000 nm, and nanosquares with dimensions of 150 × 150 nm2 were fabricated by using this direct femtosecond laser writing technique.

  7. Internal degradation of 980nm emitting single-spatial-mode lasers during ultrahigh power operation

    NASA Astrophysics Data System (ADS)

    Tomm, Jens W.; Hempel, Martin; Elsaesser, Thomas; Jimenez, Juan; Hortelano, Vanesa; Bettiati, Mauro

    2014-03-01

    Internal degradation of 980 nm emitting single-spatial-mode diode lasers during ultrahigh power operation is investigated for pulsed operation (2 μJ, 20 W). Analysis of the evolution of the emission nearfield with picosecond time resolution enables the observation of the transition from single- to multi-spatial-mode operation at elevated emission powers. Moreover, internal degradation events and subsequent defect propagation processes are in situ monitored by thermal imaging. Subsequently, these devices are opened and defect pattern are inspected by cathodo- and photoluminescence spectroscopy. The results complete earlier findings obtained with broad-area lasers and help to establish models covering defect generation and propagation in edge-emitting devices in general.

  8. Recent developments in Fourier domain mode locked lasers for optical coherence tomography: imaging at 1310 nm vs. 1550 nm wavelength.

    PubMed

    Biedermann, Benjamin R; Wieser, Wolfgang; Eigenwillig, Christoph M; Huber, Robert

    2009-07-01

    We report on recent progress in Fourier domain mode-locking (FDML) technology. The paper focuses on developments beyond pushing the speed of these laser sources. After an overview of improvements to FDML over the last three years, a brief analysis of OCT imaging using FDML lasers with different wavelengths is presented. For the first time, high speed, high quality FDML imaging at 1550 nm is presented and compared to a system at 1310 nm. The imaging results of human skin for both wavelengths are compared and analyzed. Sample arm optics, power on the sample, heterodyne gain, detection bandwidth, colour cut levels and sample location have been identical to identify the influence of difference in scattering and water absorption. The imaging performance at 1310 nm in human skin is only slightly better and the results suggest that water absorption only marginally affects the penetration depth in human skin at 1550 nm. For several applications this wavelength may be preferred.

  9. Diode-pumped quasi-three-level 456-nm Nd:GdVO{sub 4} laser

    SciTech Connect

    Zavartsev, Yu D; Zagumennyi, A I; Kutovoi, S A; Mikhailov, V A; Podreshetnikov, V V; Sirotkin, A A; Shcherbakov, Ivan A; Zerrouk, F

    2003-07-31

    A diode-pumped quasi-three-level Nd:GdVO{sub 4} laser emitting at a wavelength of 912 nm corresponding to the {sup 4}F{sub 3/2} - {sup 4}I{sub 9/2} transition of the neodymium ion and at the second-harmonic linewidth of 456 nm after intracavity frequency doubling in a KNbO{sub 3} crystal is studied. The maximum output power at the fundamental frequency was 2.96 W and the conversion efficiency amounted to 48 %. The second-harmonic output power achieved 220 mW for the conversion efficiency of 15 %. (special issue devoted to the memory of academician a m prokhorov)

  10. A single-frequency, diode-pumped Nd:YLF laser at 657 nm: a frequency and intensity noise comparison with an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Nunez Portela, M.; Wetter, N. U.; Zondy, J. J.; Cruz, F. C.

    2013-02-01

    We report on a continuous wave, diode-pumped, intracavity frequency-doubled Nd:YLF (yttrium lithium fluoride) single-frequency ring laser designed for high-resolution spectroscopy of the calcium intercombination transition at 657 nm. We measured its frequency modulation (FM) and amplitude modulation (AM) noise and compared it with an extended cavity diode laser (ECDL). The Nd:YLF laser has much lower FM noise, extending to 50 kHz in comparison with 5 MHz for the ECDL, and slightly higher AM noise, transferred from the pump diode laser. This characterization is important for the design of servo-systems for frequency or intensity stabilization, and also for quantum optics experiments. A Nd:YLF laser at 657 nm can become an attractive high-power ‘local oscillator’ for a calcium optical clock, with a fundamental ‘telecom wavelength’ that can be directly used for remote transfer in optical fibers.

  11. Laser transit anemometer experiences in supersonic flow

    NASA Technical Reports Server (NTRS)

    Hunter, William W., Jr.; Humphreys, William M., Jr.

    1988-01-01

    The purpose of this paper is to present examples of velocity measurements obtained in supersonic flow fields with the laser transit anemometer system. Velocity measurements of a supersonic jet exhausting in a transonic flow field, a cone boundary survey in a Mach 4 flow field, and a determination of the periodic disturbance frequencies of a sonic nozzle flow field are presented. Each of the above three cases also serves to illustrate different modes of laser transit anemometer operation. A brief description of the laser transit anemometer system is also presented.

  12. Frequency stabilized diode laser with variable linewidth at a wavelength of 404.7  nm.

    PubMed

    Rein, Benjamin; Walther, Thomas

    2017-04-15

    We report on a frequency stabilized laser system with a variable linewidth at a wavelength of 404.7 nm used as an incoherent repump on the 6P30↔7S31 transition in mercury. By directly modulating the laser diode current with Gaussian white noise, the laser linewidth can be broadened up to 68 MHz. A Doppler-free dichroic atomic vapor laser lock spectroscopy provides an error signal suitable for frequency stabilization even for the broadened laser. Without the need of an acousto-optic modulator for the linewidth tuning or lock-in technique for frequency stabilization, this laser system provides an inexpensive approach for an incoherent and highly efficient repumper in atomic experiments.

  13. High power single lateral mode 1050 nm laser diode bar

    NASA Astrophysics Data System (ADS)

    Liu, Guoli; Li, Jingwei; Fan, Li; Xu, Zuntu; Morales, John; Schleuning, David; Bian, Zhixi; Peters, Michael; Winhold, Heiko; Acklin, Bruno

    2017-02-01

    We present recent development of single lateral mode 1050 nm laser bars. The devices are based on an InGaAs/AlGaAs single quantum well and an asymmetric large optical cavity waveguide structure. By optimizing the AlGaAs composition, doping profiles, and QW thickness, the low internal loss of 0.5 cm-1 and high internal quantum efficiency of 98% are obtained. A standard bar (10% fill factor; 4mm cavity length) reaches 72% peak electro-optical efficiency and 1.0 W/A slope efficiency at 25°C. To achieve high single lateral mode power, the current confinement and optical loss profile in lateral direction are carefully designed and optimized to suppress higher order lateral modes. We demonstrate 1.5W single lateral mode power per emitter from a 19-emitter 10mm bar at 25°C. High electro-optical efficiency are also demonstrated at 25°C from two separate full-bar geometries on conduction cooled packaging: 20 W with <50% electro-optical efficiency from a 19-emitter bar and 50 W with <45% electro-optical efficiency from a 50-emitter bar.

  14. DFB-ridge laser diodes at 894 nm for Cesium atomic clocks

    NASA Astrophysics Data System (ADS)

    von Bandel, N.; Garcia, M.; Lecomte, M.; Larrue, A.; Robert, Y.; Vinet, E.; Driss, O.; Parrilaud, O.; Krakowski, M.; Gruet, F.; Matthey, R.; Mileti, G.

    2016-02-01

    Time and frequency applications are in need of high accuracy and high stability clocks. Optically pumped compact industrial Cesium atomic clocks are a promising approach that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of the laser diodes that are used. This issue has led the III-V Lab to commit to the European Euripides-LAMA project that aims to provide competitive compact optical Cesium clocks for ground applications. This work will provide key experience for further space technology qualification. III-V Lab is in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894 nm (D1 line of Cesium) and 852 nm (D2 line). LTF-Unine is in charge of their spectral characterisation. The use of D1 line for pumping will provide simplified clock architecture compared to the D2 line pumping thanks to simpler atomic transitions and a larger spectral separation between lines in the 894 nm case. Also, D1 line pumping overcomes the issue of unpumped "idle states" that occur with D2 line. The modules should provide narrow linewidth (<1 MHz), very good reliability in time and, crucially, be less sensitive to optical feedback. The development of the 894 nm wavelength is grounded on III-V Lab results for 852 nm DFB. We show here results from Al-free active region with InGaAsP quantum well Ridge DFB lasers. We obtain the D1 Cs line (894.4 nm) at 67°C and 165 mA (optical power of 40 mW) with a high side mode suppression ratio. The wavelength evolution with temperature and current are respectively 0.06 nm/K and 0.003 nm/mA. The laser linewidth is less than 1 MHz. The Relative Intensity Noise (RIN) and the frequency noise are respectively less than 10-12 Hz-1 @ f >= 10 Hz and 109 Hz2/Hz @ f >= 10 Hz.

  15. Laser Ablation of Dental Calculus Around 400 nm Using a Ti:Sapphire Laser

    SciTech Connect

    Schoenly, J.; Seka, W.; Rechmann, P.

    2009-10-19

    A Nd:YAG laser-pumped, frequency-doubled Ti:sapphire laser is used for selective ablation of calculus. The laser provides ≤25 mJ at 400 nm (60-ns pulse width, 10-Hz repetition rate). The laser is coupled into an optical multimode fiber coiled around a 4-in.-diam drum to generate a top-hat output intensity profile. With coaxial water cooling, this is ideal for efficient, selective calculus removal. This is in stark contrast with tightly focused Gaussian beams that are energetically inefficient and lead to irreproducible results. Calculus is well ablated at high fluences ≥2 J/cm^2; stalling occurs below this fluence because of photobleaching. Healthy hard tissue is not removed at fluences ≤3 J/cm^2.

  16. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    SciTech Connect

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Chamorovsky, A Yu; Yakubovich, S D

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  17. Pulsed dermatologic 20W diode-laser emitting at 975-nm

    NASA Astrophysics Data System (ADS)

    Piechowski, L.; Cenian, W.; Sawczak, M.; Cenian, A.

    2013-01-01

    The pulsed dermatologic laser for photothermolysis is constructed basing on technology of 975 nm diode lasers developed for fiber-laser excitation. In near future these lasers can replace ND:YAG ones for dermatologic applications, especially therapy of deep skin diseases.

  18. RELATIVISTIC CALCULATION OF TRANSITION PROBABILITIES FOR 557.7 nm AND 297.2 nm EMISSION LINES IN OXYGEN

    SciTech Connect

    Chantler, C. T.; Nguyen, T. V. B.; Lowe, J. A.; Grant, I. P.

    2013-05-20

    The 557.7 nm green line and the 297.2 nm ultraviolet line in oxygen have been studied extensively due to their importance in astrophysics and atmospheric science. Despite the enormous effort devoted to these two prominent transition lines over 30 years, and in fact going back to 1934, the ratio of their transition probabilities remains a subject of major discrepancies amongst various theoretical calculations for many decades. Moreover, theoretical results are inconsistent with available laboratory results, as well as recent spacecraft measurements of Earth's airglow. This work presents new relativistic theoretical calculations of the transition probabilities of these two photoemission lines from neutral oxygen using the multi-configuration Dirac-Hartree-Fock method. Our calculations were performed in both length and velocity gauges in order to check for accuracy and consistency, with agreement to 8%. Whilst remaining a challenging computation, these results directly bear upon interpretations of plasma processes and ionization regimes in the universe.

  19. High-resolution laser spectroscopy on H2 at 97 98 nm

    NASA Astrophysics Data System (ADS)

    Hinnen, P. C.; Hogervorst, W.; Stolte, S.; Ubachs, W.

    1994-09-01

    A narrowband tunable eXtreme UltraViolet (XUV) laser source is used for a high resolution study of the Lyman ( B 1 Σ {/u +} ™ X 1 Σ {/g +}) band system of molecular hydrogen. Seven rotational transitions of two vibrational bands, (10,0) and (11,0), in the wavelength range from 97.2 98.3 nm have been investigated for the first time under sub-Doppler molecular beam conditions. A calibration procedure using the I2 standard in the visible yielded an absolute frequency accuracy of 0.02 cm-1. The obtained H2 transition frequencies provide a calibration standard in the extreme ultraviolet wavelength region.

  20. Direct laser interference patterning of polystyrene films doped with azo dyes, using 355 nm laser light

    NASA Astrophysics Data System (ADS)

    Broglia, M. F.; Suarez, S.; Soldera, F.; Mücklich, F.; Barbero, C. A.; Bellingeri, R.; Alustiza, F.; Acevedo, D.

    2014-05-01

    The generation of line-like periodic patterns by direct laser interference patterning (DLIP) of polystyrene films (PS) at a wavelength of 355 nm has been investigated. No structuration is achieved in plain PS due to the weak absorption of the polymer at 355 nm. On the other hand, patterning is achieved on films doped (PSd) with an azo dye (2-anisidine → 2-anisidine) which is incorporated in the polymer solution used for film preparation. Periodic micro-structures are generated. DLIP on PSd results in the swelling of the surface at low fluences, while at high laser intensities it causes the ablation of the regions at the interference maxima positions. The results contrast with the usual process of DLIP on PS (at shorter wavelengths, like 266 nm) where only ablation is detected. The results suggest that decomposition of the azo dye is the driving force of the patterning which therefore differ from the patterning obtained when plain PS is irradiated with laser light able to be absorbed by the aromatic ring in PS (e.g. 266 nm). The biocompatibility of these materials and adhesion of cells was tested, the data from in vitro assays shows that fibroblast cells are attached and proliferate extensively on the PSd films.

  1. UV Laser Conditioning for Reduction of 351-nm Damage Initiation in Fused Silica

    SciTech Connect

    Brusasco, R M; Penetrante, B M; Peterson, J E; Maricle, S M; Menapace, J A

    2001-12-20

    This paper describes the effect of 355-nm laser conditioning on the concentration of UV-laser-induced surface damage sites on large-aperture fused silica optics. We will show the effect of various 355-nm laser conditioning methodologies on the reduction of surface-damage initiation in fused silica samples that have varying qualities of polishing. With the best, generally available fused silica optic, we have demonstrated that 355-nm laser conditioning can achieve up to 10x reduction in surface damage initiation concentration in the fluence range of 10-14 J/cm{sup 2} (355-nm {at} 3 ns).

  2. 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.

  3. Treatment of 308-nm excimer laser on vitiligo: A systemic review of randomized controlled trials.

    PubMed

    Sun, Yan; Wu, Yan; Xiao, Bihuan; Li, Lu; Li, Li; Chen, Hong-Duo; Gao, Xing-Hua

    2015-01-01

    Vitiligo is an acquired cutaneous hypopigmentary disorder, which characterized by solitary or multiple depigmented maculae or patches. The 308-nm excimer laser has been used as phototherapy on vitiligo. To evaluate the efficacy and safety of 308-nm excimer laser on vitiligo. Randomized controlled trials were searched to conduct a systematic review. The keywords were identified as laser/excimer laser/quasimolecule/XeCl" and "vitiligo". Seven studies with 390 vitiligo patients were included. No significant differences were seen between 308-nm excimer laser and 308-nm excimer lamp on either ≥75% or ≥50% re-pigmentation rate, or between 308-nm excimer laser and narrowband-ultraviolet B (NB-UVB) on either 100% or ≥75% re-pigmentation rate. More patients or lesions achieved ≥50% re-pigmentation rate by 308-nm excimer laser treatment than by NB-UVB treatment. The side effects of 308-nm excimer laser were slight and tolerable. The 308-nm excimer laser showed equivalent efficacies to 308-nm excimer lamp control and NB-UVB control concerning ≥75% re-pigmentation rate of vitiligo patches. More studies with high methodological quality, low risk of bias and more sample size are needed to confirm the conclusion.

  4. 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.

  5. 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.

  6. 20 W continuous-wave cladding-pumped Nd-doped fiber laser at 910 nm.

    PubMed

    Laroche, M; Cadier, B; Gilles, H; Girard, S; Lablonde, L; Robin, T

    2013-08-15

    We demonstrate a double-clad fiber laser operating at 910 nm with a record power of 20 W. Laser emission on the three-level scheme is enabled by the combination of a small inner cladding-to-core diameter ratio and a high brightness pump source at 808 nm. A laser conversion efficiency as high as 44% was achieved in CW operating regime by using resonant fiber Bragg reflectors at 910 nm that prevent the lasing at the 1060 nm competing wavelength. Furthermore, in a master oscillator power-amplifier scheme, an amplified power of 14.8 W was achieved at 914 nm in the same fiber.

  7. Comparative investigation of laser-induced breakdown spectroscopy in bulk water using 532- and 1064-nm lasers

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Xue, Boyang; Song, Jiaojian; Lu, Yuan; Li, Ying; Zheng, Ronger

    2017-07-01

    The influence of laser wavelength on the characteristics of laser-induced breakdown spectroscopy (LIBS) in bulk water was investigated by using 532- and 1064-nm lasers. We demonstrated that higher laser energy does not lead to higher LIBS signals because of the strong plasma shielding occurring at high laser energies, as shown by the spectroscopic and fast imaging results in this work. At threshold energies of 100% breakdown probability, the 1064 nm beam could induce a plasma with higher electron density and temperature than the 532 nm beam, which leads to higher signal-to-noise ratios and longer lifetimes of the emission lines.

  8. Absolute frequency measurement of the 674-nm {sup 88}Sr{sup +} clock transition using a femtosecond optical frequency comb

    SciTech Connect

    Margolis, H.S.; Huang, G.; Barwood, G.P.; Lea, S.N.; Klein, H.A.; Rowley, W.R.C.; Gill, P.; Windeler, R.S.

    2003-03-01

    The frequency of the 5s {sup 2}S{sub 1/2}-4d {sup 2}D{sub 5/2} electric quadrupole transition at 674 nm in a single, trapped, laser-cooled {sup 88}Sr{sup +} ion has been measured with respect to the Systeme International (SI) second using a femtosecond laser optical frequency comb. The measured frequency of 444 779 044 095.52 kHz, with an estimated standard uncertainty of 0.10 kHz, is more accurate than, and in agreement with, the value previously measured using a conventional frequency chain.

  9. Low threshold CW Nc laser oscillator at 1060 nm study

    NASA Technical Reports Server (NTRS)

    Birnbaum, M.; Deshazer, L. G.

    1976-01-01

    A broad range of characteristics of neodymium/yag lasers were investigated. With Nd:YVO4 crystals, CW 1.06 mu lasers were operated with thresholds a factor of 2 lower than Nd:YAG and with greater slope efficiencies. Thus, the first step in the development of new oscillators suitable for application in high data rate laser communication systems which surpass the present performance of the Nd:YAG laser has been successfully demonstrated.

  10. 21nm x-ray laser Thomson scattering of laser-heated exploding foil plasmas

    SciTech Connect

    Dunn, J; Rus, B; Mocek, T; Nelson, A J; Foord, M E; Rozmus, W; Baldis, H A; Shepherd, R L; Kozlova, M; Polan, J; Homer, P; Stupka, M

    2007-09-26

    Recent experiments were carried out on the Prague Asterix Laser System (PALS) towards the demonstration of a soft x-ray laser Thomson scattering diagnostic for a laser-produced exploding foil. The Thomson probe utilized the Ne-like zinc x-ray laser which was double-passed to deliver {approx}1 mJ of focused energy at 21.2 nm wavelength and lasting {approx}100 ps. The plasma under study was heated single-sided using a Gaussian 300-ps pulse of 438-nm light (3{omega} of the PALS iodine laser) at laser irradiances of 10{sup 13}-10{sup 14} W cm{sup -2}. Electron densities of 10{sup 20}-10{sup 22} cm{sup -3} and electron temperatures from 200 to 500 eV were probed at 0.5 or 1 ns after the peak of the heating pulse during the foil plasma expansion. A flat-field 1200 line mm{sup -1} variable-spaced grating spectrometer with a cooled charge-coupled device readout viewed the plasma in the forward direction at 30{sup o} with respect to the x-ray laser probe. We show results from plasmas generated from {approx}1 {micro}m thick targets of Al and polypropylene (C{sub 3}H{sub 6}). Numerical simulations of the Thomson scattering cross-sections will be presented. These simulations show electron peaks in addition to a narrow ion feature due to collective (incoherent) Thomson scattering. The electron features are shifted from the frequency of the scattered radiation approximately by the electron plasma frequency {+-}{omega}{sub pe} and scale as n{sub e}{sup 1/2}.

  11. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 2.17 W output power at 543 nm

    NASA Astrophysics Data System (ADS)

    Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

    2013-03-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a CW diode-pumped Nd:LuVO4 laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 16 W of diode pump power and the frequency-doubling crystal LBO, as high as 2.17 W of CW output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 13.6% and the output power stability over 8 hours is better than 2.86%. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1086 nm.

  12. Component validation of direct diode 488nm lasers in BD Accuri C6 flow cytometers

    NASA Astrophysics Data System (ADS)

    Chen, Wei P.; Luo, Ningyi D.

    2016-03-01

    The 488nm laser is the most important excitation light source of flow cytometry. The indirect diode (frequency-doubled diode) 488nm lasers are used in the excitation of Becton Dickinson (BD) AccuriTM C6. For using cost effective lasers, we have validated direct diode 488nm lasers as the replacement component of frequency-doubled diode laser. BD Bioscience issued the protocols to cover wavelength, power, noise, and polarization at the operation temperature range of cytometer. Pavilion Integration Corporation (PIC) tested 6 samples as the component validation of direct diode 488nm lasers based on the protocols from BD Biosciences. BD Bioscience also tested one of laser samples to further validate the test results of power, noise, and polarization from PIC.

  13. Megahertz FDML laser with up to 143nm sweep range for ultrahigh resolution OCT at 1050nm

    NASA Astrophysics Data System (ADS)

    Kolb, Jan Philip; Klein, Thomas; Eibl, Matthias; Pfeiffer, Tom; Wieser, Wolfgang; Huber, Robert

    2016-03-01

    We present a new design of a Fourier Domain Mode Locked laser (FDML laser), which provides a new record in sweep range at ~1μm center wavelength: At the fundamental sweep rate of 2x417 kHz we reach 143nm bandwidth and 120nm with 4x buffering at 1.67MHz sweep rate. The latter configuration of our system is characterized: The FWHM of the point spread function (PSF) of a mirror is 5.6μm (in tissue). Human in vivo retinal imaging is performed with the MHz laser showing more details in vascular structures. Here we could measure an axial resolution of 6.0μm by determining the FWHM of specular reflex in the image. Additionally, challenges related to such a high sweep bandwidth such as water absorption are investigated.

  14. Precision frequency measurements of He,43 2 3P→3 3D transitions at 588 nm

    NASA Astrophysics Data System (ADS)

    Luo, Pei-Ling; Peng, Jin-Long; Hu, Jinmeng; Feng, Yan; Wang, Li-Bang; Shy, Jow-Tsong

    2016-12-01

    We report the frequency measurements of the 2 3P→3 3D transitions in He,43 at 588 nm using an optical frequency comb stabilized laser system. The Doppler-free spectra of the 2 3P→3 3D transitions are demonstrated in an rf discharged sealed-off helium cell using intermodulated fluorescence spectroscopy. The measured absolute frequency of the 4He2 3P0→3 3D1 transition is 510 059 755.352(28) MHz, which is more precise than the previous measurement by two orders of magnitude. The ionization energies of the 4He2 3P0 and 2 3S1 states can be derived from our result and agree very well with the previous experimental values. More importantly, the Lamb shift of the 2 3S1 state can be deduced to be 4057.086(34) MHz, which is two times more precise than the previous result. In addition, the absolute frequencies of the 2 3P0,1 /2→3 3D1,3 /2 , 2 3P0,1 /2→3 3D1,1 /2 , and 2 3P0,1 /2→3 3D2,3 /2 transitions in 3He are measured. Our precision surpasses the theoretical calculations by more than one to two orders of magnitude. The hyperfine separations of the 3 3D states in 3He and the frequency differences between 4He and 3He transitions are also presented.

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

    PubMed

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

    2017-06-15

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

  16. Femtosecond laser-written lithium niobate waveguide laser operating at 1085 nm

    NASA Astrophysics Data System (ADS)

    Tan, Yang; de Aldana, Javier R. Vázquez; Chen, Feng

    2014-10-01

    We report on the channel waveguide lasers at 1085 nm in femtosecond laser written Type II waveguides in an Nd:MgO:LiNbO3 crystal. The waveguide was constructed in a typical dual-line approach. In the geometry, we found that four vicinal regions of the track pair could guide light propagation. In addition, these guiding cores support polarization-dependent-guided modes. The propagation losses of the waveguides were measured to be as low as 1 dB/cm. Under an optical pump at 808 nm, the continuous-wave waveguide lasing at 1085 nm was generated, reaching a slope efficiency of 27% and maximum output power of 8 mW. The lasing threshold was 71 mW. Our results show that with the femtosecond laser written Nd:MgO:LiNbO3 waveguide as the miniature light source, it was possible to construct all-LiNbO3-based integrated devices for diverse photonic applications.

  17. Effects of the 532-nm and 1,064-nm Q-switched Nd:YAG lasers on collagen turnover of cultured human skin fibroblasts: a comparative study.

    PubMed

    Dang, Yongyan; Ye, Xiyun; Weng, Yujing; Tong, Zhi; Ren, Qiushi

    2010-09-01

    Cultured human skin fibroblasts were irradiated twice successively with the 1.5 J/cm(2) of 532-nm and 1,064-nm lasers, respectively. The mRNA of procollagen, matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), heat-shock protein 70 (Hsp70), interleukin-6 (IL-6) and transforming growth factor beta (TGF-beta) were analyzed at 24 and 48 h post-irradiation by using RT-PCR. Both lasers significantly increased the expression of type I and III procollagen, TIMP1, and TIMP2, but decreased MMP1 and MMP2 expression. The 1,064-nm laser initiated TGF-beta expression while the 532-nm laser elicited the increase of Hsp70 and IL-6. The increase/decrease rates of procollagen, TIMPs and MMPs for the 1,064-nm laser were higher than that of the 532-nm laser. Thus, both lasers effectively accelerated collagen synthesis and inhibited collagen degradation. Collagen synthesis induced by the 1,064-nm laser might be partly due to the upregulation of TGF-beta expression, while the increase of Hsp70 and IL-6 might be partly responsible for collagen synthesis stimulated by the 532-nm laser. With the parameters used in this study, the 1,064-nm infrared laser is more effective in promoting the beneficial molecular activities than the 532-nm visible laser.

  18. High-average-power, 100-Hz-repetition-rate, tabletop soft-x-ray lasers at sub-15-nm wavelengths

    SciTech Connect

    Reagan, Brendon; Berrill, Mark A; Wernsing, Keith; Baumgarten, Cory; Woolston, Mark; Rocca, Jorge

    2014-01-01

    Efficient excitation of dense plasma columns at 100-Hz repetition rate using a tailored pump pulse profile produced a tabletop soft-x-ray laser average power of 0.1 mW at = 13.9 nm and 20 W at = 11.9 nm from transitions of Ni-like Ag and Ni-like Sn, respectively. Lasing on several other transitions with wavelengths between 10.9 and 14.7 nm was also obtained using 0.9-J pump pulses of 5-ps duration from a compact diode-pumped chirped pulse amplification Yb:YAG laser. Hydrodynamic and atomic plasma simulations show that the pump pulse profile, consisting of a nanosecond ramp followed by two peaks of picosecond duration, creates a plasma with an increased density of Ni-like ions at the time of peak temperature that results in a larger gain coefficient over a temporally and spatially enlarged space leading to a threefold increase in the soft-x-ray laser output pulse energy. The high average power of these compact soft-x-ray lasers will enable applications requiring high photon flux. These results open the path to milliwatt-average-power tabletop soft-x-ray lasers.

  19. LASERS: A 223-nm KrCl excimer laser on a He—Kr—HCl mixture

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Zhupikov, A. A.; Kargapol'tsev, E. S.

    2004-02-01

    The results of experimental studies of the parameters of a 223-nm electric-discharge KrCl excimer laser on a He—Kr—HCl mixture depending on the excitation conditions and the composition of the active gaseous medium are presented. To achieve the maximum values of the output energy and the efficiency of the KrCl laser on mixtures with buffer gaseous helium, an excitation system was used that included a circuit with an LC inverter with a high-voltage switch based on an RU-65 spark gap. An output energy of 320 mJ with an efficiency of 0.5% relative to the energy stored in the capacitors is obtained in a KrCl laser with an active medium based on the buffer He gas at a charging voltage of 30 kV. Radiation pulses with a duration of 22±1 ns and a pulse power of 15 MW are obtained.

  20. Comparison of laser iridotomy using short duration 532-nm Nd: YAG laser (PASCAL) vs conventional laser in dark irides.

    PubMed

    Chung, Hye Jin; Park, Hae-Young; Kim, Su-Young

    2015-01-01

    To evaluate the outcome of laser iridotomy using 532-nm Nd: YAG laser (PASCAL) with short pulse duration and Nd: YAG laser compared to conventional combined laser iridotomy. Retrospective, nonrandomized, comparative case series. Forty-five eyes of 34 patients underwent laser iridotomy. Twenty-two eyes underwent iridotomy using short duration PASCAL and Nd: YAG laser, and 23 eyes underwent iridotomy using conventional combined laser method. The average settings of PASCAL were 60 µm and 700-900 mW with a short duration of 0.01s to reduce the total applied energy. The conventional laser was 50 µm and 700-900 mW for 0.1s. After photocoagulation with these laser, the Nd: YAG laser was added in each group. Endothelial cell counts of pre-iridotomy and 2mo after iridotomy were measured and compared. All eyes completed iridotomy successfully. The total energy used in the PASCAL group was 1.85±1.17 J. Compared to conventional laser 13.25±1.67 J, the energy used was very small due to the short exposure time of PASCAL. Endothelial cell counts were reduced by 0.88% in the PASCAL group and 6.72% in the conventional laser group (P=0.044). The change in corneal endothelial cell counts before and after iridotomy was significant in conventional combined laser iridotomy group (P=0.004). Combined PASCAL and Nd:YAG laser iridotomy is an effective and safe technique in the dark brown irides of Asians. Furthermore, the short duration of exposure in PASCAL offers the advantages of reducing the total energy used and minimizing the corneal damage.

  1. Mid-IR Transition Metal Lasers (Postprint)

    DTIC Science & Technology

    2007-01-01

    alexandrite was demonstrated in 1979. [2] Cr4+ and Cr2+ infrared laser materials took even longer to be discovered. However, transition metal laser...already been mentioned. Other transition metal laser ions such as Cr3+ in alexandrite [19] and Ti3+ in YAlO3 [20] have excited state absorption (ESA...Washington, DC. 19. Shand, M.L., J.C. Walling, and R.C. Morris, Excited-state absorption in the pump region of alexandrite , Journal of Applied Physics

  2. Study of the emission spectra of a 1320-nm semiconductor disk laser and its second harmonic

    SciTech Connect

    Gochelashvili, K S; Derzhavin, S I; Evdokimova, O N; Zolotovskii, I O; Podmazov, S V

    2016-03-31

    The spectral characteristics of an optically pumped external-cavity semiconductor disk laser near λ = 1320 nm are studied experimentally. Intracavity second harmonic generation is obtained using an LBO nonlinear crystal. The output power at a wavelength of 660 nm in the cw regime was 620 mW, and the peak power in the pulsed regime was 795 mW. (lasers)

  3. Degradation mechanism of laser diodes for 880-nm band

    NASA Astrophysics Data System (ADS)

    DÄ browska, E.; Nakielska, M.; Kozłowska, A.; Teodorczyk, M.; KrzyŻak, K.; Sobczak, G.; Kalbarczyk, J.; MalÄ g, A.

    2013-01-01

    The laser diodes (LD) have numerous applications and promise to become key elements for next generation laser technologies. LD are usually operated under conditions of heavy thermal load. As a result, the devices are affected by aging processes leading to changes of the operation parameters, degradation and, eventually, complete failure. Degradation of high power semiconductor lasers remains a serious problem for practical application of these devices. We investigated the effect of mounting induced strain and defects on the performance of high power laser. In this paper measurements of the temperature distribution and the electroluminescence along the cavity of InGaAs quantum well lasers before and after accelerated aging processes are presented. The electro-optical parameters of the high output power laser diodes, such as emission wavelength, output power, threshold current, slope efficiency, and operating lifetime are presented too.

  4. Fractionated photothermolysis: the Fraxel 1550-nm glass fiber laser treatment.

    PubMed

    Chiu, Robert J; Kridel, Russell W H

    2007-05-01

    The carbon dioxide laser has been long considered to be the gold standard for cosmetic skin resurfacing. Although Fraxel laser treatment results are in general not as dramatic as with carbon dioxide lasering, they still are remarkable, measurable, and consistent. The lack of downtime and the decreased risk for complications make Fraxel laser treatment a particularly attractive choice for patients. Although a carbon dioxide laser cannot be used on the neck because of the risks of scarring, the Fraxel laser treatment is an excellent modality for reducing neck wrinkling and upper chest hyperpigmentation and sun damage throughout the entire body. Fractional photothermolysis also represents a particularly useful modality for difficult-to-treat conditions, such as melasma and acne scarring.

  5. Temperature dependence of the dielectric function of laser deposited YBCO thin film at 3392nm

    SciTech Connect

    Walmsley, D.G.; Bade, T.; McCafferty, P.G.; Rea, C.; Dawson, P.; Wallace, R.J.; Bowman, R.M.

    1996-12-31

    The authors have excited surface plasmons in an YBCO thin film at different temperatures using attenuated total reflection of light. The 300nm thick c-axis film was fabricated using pulsed laser deposition onto an MgO (100) substrate with 248nm KrF excimer radiation. Critical temperature of the film was 89.6K and its roughness, as shown by atomic force microscopy, 20nm rms, without droplets over areas of 10 {micro}m x 10{micro}m. The sample was mounted in Otto geometry on a cooled stage which allowed the temperature to be varied between 300K and 70K. An infrared HeNe laser at 3,392nm was used to excite the surface plasmons. The dielectric function of the film was determined between room temperature and 80K. The imaginary part of the dielectric function decreased substantially with reduction in temperature. Results obtained were: {var_epsilon}{sub r} = {minus}24.1 + 0.0013T and {var_epsilon}{sub i} = 7.7 + 0.067T where T is the temperature in kelvin. The ratio {var_epsilon}{sub i}{sup 300}/{var_epsilon}{sub i}{sup 80} at 2.13 is less than the resistance ratio R{sup 300}/R{sup 80} at 2.81. An explanation is offered in terms of two temperature independent mechanisms operative at optical frequencies: enhanced Rayleigh scattering of surface plasmons at grain boundaries and intraband/interband transitions. The real part of the dielectric function, {var_epsilon}{sub r}, was found to be only slightly temperature dependent. It was, however, highly sample dependent when comparison was made with the results of other films, a feature attributed to surface and grain boundary contamination.

  6. High power single-longitudinal-mode cyan laser at 500.8 nm

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    An all-solid-state single-longitudinal-mode (SLM) laser at 500.8 nm with 830 mW output power has been demonstrated for the first time. By using a new resonator for doubly resonant, Nd:GdVO4 and Nd:YAG were pumped by two laser diode arrays coupled by optical fiber, respectively. In the two sub-cavities, SLM wavelengths of 1064 and 946 nm were induced by using the twisted-mode technique and then mixed into SLM 500.8 nm laser with sum-frequency technology. The SLM 500.8 nm laser output of 830 mW was obtained at the incident pump power of 20 W for Nd:GdVO4 and 23 W for Nd:YAG. The experimental results showed that the intracavity sum-frequency mixing by twisted-mode technique is an effective method for SLM 500.8 nm laser.

  7. A tunable, Nd-doped lithium niobate laser at 1084 nm

    SciTech Connect

    Schearer, L.D. ); Leduc, M.

    1988-10-01

    Over 250 mW of CW laser emission at 1084 nm is obtained from Nd:LiNbO{sub 3} when the rod is end-pumped along the crystalline {open quote}{ital y}{close quote} axis by 1 W from a Kr{sup +} laser at 752 nm. The laser can be tuned over 3 nm at the 1084 nm peak with a thin, uncoated etalon in the cavity. Thresholds of 30 mW of absorbed pump power were obtained with a weak output coupler, rising to 220 mW with a 35% transmitting output mirror. No pump-induced photorefractive effects were observed.

  8. 1,450-nm diode laser in combination with the 1550-nm fractionated erbium-doped fiber laser for the treatment of steatocystoma multiplex: a case report.

    PubMed

    Moody, Megan N; Landau, Jennifer M; Goldberg, Leonard H; Friedman, Paul M

    2012-07-01

    Steatocystoma multiplex (SM) is a rare condition characterized by multiple, small, asymptomatic dermal cysts. Treatment options are limited, with varying degrees of success; these include oral isotretinoin, surgical excision or drainage, and liquid nitrogen cryotherapy. The most effective method is excision, but cosmetic considerations, time, overall cost, and pain must be considered, because patients tend to have multiple cysts. Lasers, especially nonablative devices, have not frequently been used to treat SM. Herein, we present the case of a patient with isolated steatocystoma multiplex on the abdomen and lower chest with substantial clearance after two laser treatment sessions using two complementary lasers: a 1,450-nm diode laser to target the abnormal sebaceous glands and a 1,550-nm fractionated erbium-doped fiber laser to target the dermal cysts. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  9. 7-W single-mode thulium-doped fibre laser pumped at 1230 nm

    SciTech Connect

    Kravtsov, K S; Bufetov, Igor' A; Medvedkov, O I; Dianov, Evgenii M; Yashkov, M V; Gur'yanov, A N

    2005-07-31

    An efficient thulium-doped fibre laser emitting at {approx}2 {mu}m upon pumping into the long-wavelength {sup 3}H{sub 6} {yields} {sup 3}H{sub 5} absorption band of Tm{sup 3+} ions is developed. The maximum output power of the single-mode thulium laser pumped at 1230 nm was 7 W at 1956 nm for a pump conversion efficiency of 35%. (lasers)

  10. Formation of sub-200 nm nanostructure on Fe film irradiated by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Liu, Kaijun; Li, Xiaohong; Xie, Changxin; Wang, Kai; Zhou, Qiang; Qiu, Rong

    2017-09-01

    In this article, we report the formation of two kinds of laser induced periodic surface structures (LIPSSs) with direction perpendicular to laser polarization on the Fe films irradiated by 800 nm femtosecond laser pulses. High-spatial frequency LIPSSs (HSFLs) with periods of 150-230 nm are observed with small laser pulse number less than 100. Low-spatial frequency LIPSSs (LSFLs) with periods of 500-640 nm appear abruptly when increasing the pulse number to a specific pulse number varied with laser fluence, and the periods of LSFLs have a tendency to decrease when the pulse number exceeds some specific values varied for different laser fluences. The formation of high- and low-spatial frequency periodic structures may be related to the surface plasmon polaritons excited by laser on surface iron oxides film or iron film.

  11. Comparison of 532 nm Potassium Titanyl Phosphate Laser and 595 nm Pulsed Dye Laser in the Treatment of Erythematous Surgical Scars: A Randomized, Controlled, Open-Label Study.

    PubMed

    Keaney, Terrence C; Tanzi, Elizabeth; Alster, Tina

    2016-01-01

    The pulsed dye laser (PDL) has long been used for treatment of erythematous and hypertrophic scars. Its effectiveness has been attributed in large part to its vascular-specificity. The vascular-specific potassium titanyl phosphate (KTP) laser has also been reported to be clinically effective for scars, but has not been compared to the PDL. To compare the safety and clinical efficacy of a 532-nm KTP laser versus a 595-nm PDL in improving the appearance of erythematous surgical scars. Twenty patients with matched bilateral erythematous surgical scars or a single linear erythematous scar measuring longer than 5 cm were enrolled in the study. Single scars were divided into equal halves with each half randomized to receive 3 successive treatments at 6-week intervals with either a 532-nm KTP laser (Excel V; Brisbane, CA) or a 595-nm PDL (Cynergy; Cynosure Inc., Chelmsford, MA) at equivalent laser parameters. Bilateral matched scars were similarly randomized to receive three 532-nm KTP or 595-nm PDL treatments. Clinical efficacy was evaluated 12 weeks after the third (final) laser treatment by independent, blinded photographic scar assessments. Secondary evaluations included final investigator and subject treatment/satisfaction assessments, Vancouver scar scale (VSS) scores, subject scar symptoms, intraoperative pain scores, and incidence of side effects. Clinical improvement of erythematous surgical scars was observed with both 532-nm KTP and 595-nm PDL systems. No statistically significant differences between the 2 treatment arms were noted in the independent, blinded photographic scar assessments, investigator and subject treatment/satisfaction assessments, subject scar symptoms, and intraoperative pain scores. The KTP arm produced statistically significant improvement for the vascularity component of the VSS only. Side effects were limited to mild treatment discomfort and minimal transient post-treatment erythema and purpura. No vesiculation, infection, scarring or

  12. Reliability of high power/brightness diode lasers emitting from 790 to 980 nm

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  13. A 532 nm Chaotic Fiber Laser Transmitter for Underwater Lidar

    DTIC Science & Technology

    2013-04-23

    cutting, marking, and welding [72, 77, 78]. Ytterbium-doped fibers (YDFs) are particularly efficient absorbers of pump light, so very high pump powers...components at 1550 nm, but can be frustratingly high (often 30- 40%) for 1064 nm components. The mismatches between dissimilar fibers’ effective mode

  14. Laser Treatment of Professional Tattoos With a 1064/532-nm Dual-Wavelength Picosecond Laser.

    PubMed

    Kauvar, Arielle N B; Keaney, Terrence C; Alster, Tina

    2017-09-19

    Picosecond-domain laser pulses improve the photomechanical disruption of tattoos. This study evaluates the efficacy and safety of a novel, dual-wavelength, 1,064/532-nm, picosecond-domain laser for tattoo clearance. This was a prospective, self-controlled, clinical study of 34 subjects with 39 tattoos treated at 2 sites with an interval of 4.8 ± 1.6 weeks and up to 10 treatments (mean, 7.5). Blinded evaluation and investigator assessment of serial digital images was performed to evaluate treatment efficacy in the 36 tattoos that received at least 3 treatments. Investigators also assessed efficacy before each treatment visit up to 10 treatments. Safety and tolerability was evaluated for all 39 tattoos that underwent at least 1 treatment. Blinded evaluation demonstrated that lightening of tattoos was achieved in all subjects, with 86% (31 of 36 tattoos) showing at least a 50% clearance after 3 treatments. Adverse events were few and transient in nature. Patient satisfaction and treatment tolerability were high. Treatment of single-colored and multicolored tattoos with this novel 1,064/532-nm picosecond laser is highly safe and effective.

  15. Implications of the temperature dependence of Nd:YAG spectroscopic values for low temperature laser operation at 946 nm

    NASA Astrophysics Data System (ADS)

    Yoon, S. J.; Mackenzie, J. I.

    2014-05-01

    We present our measurements of the key spectroscopic properties over the temperature range of 77 K to 450 K for Nd3+ ions doped in Y3Al5O12 (YAG). From room to liquid nitrogen temperature (LNT), the peak absorption cross section around 808 nm increased by almost 3 times, in conjunction the bandwidth of this absorption line reduced by the same factor. At LNT the peak of the absorption line was blue shifted by 0.25 nm with respect to that at 300 K. The fluorescence spectrum between 850 nm - 1450 nm was measured, from which the emission cross sections for the three main transitions were calculated. One note of particular interest for the dominant emission wavelengths around 1064nm and 1061nm (4F3/2 --> 4I11/2) was the switch in their relative strength below 170K, and at LNT the 1061 nm line has almost twice the cross section as at 1064nm.. The fluorescence and lifetime of the upper laser level (4F3/2) was measured and the effective emission cross section determined by the Fuchtbauer-Ladenburg (F-L) method. The effective emission cross section for 946 nm (R1 --> Z5) increased by more than two times over the 300 K to 77 K range. A numerical fit for the temperature dependent emission cross section at 946 nm and 1064 nm and also calculated absorption coefficient at 808 nm pump diode laser have also obtained from the measured spectroscopic data.

  16. Novel 980-nm and 490-nm light sources using vertical-cavity lasers with extended coupled cavities

    NASA Astrophysics Data System (ADS)

    McInerney, John G.; Mooradian, Aram; Lewis, Alan; Shchegrov, Andrei V.; Strzelecka, Eva M.; Lee, Dicky; Watson, Jason P.; Liebman, Michael K.; Carey, Glen P.; Umbrasas, Arvydas; Amsden, Charles A.; Cantos, Brad D.; Hitchens, William R.; Heald, David L.; Doan, Vincent

    2003-06-01

    We have developed novel electrically pumped, surface-emitting lasers emitting at 980 nm with an extended coupled cavity. The concept is scalable from monolithic low power (~10 mW) devices all the way to high power extended cavity lasers. The latter have demonstrated ~1 W cw multi-mode and 0.5 W cw in a TEM00 mode and a single frequency, with 90% coupling efficiency into a single-mode fiber. By inserting a nonlinear optical medium in the external cavity, efficient and compact frequency doubling has been achieved with CW output powers 5-40 mW demonstrated at 490 nm. The latter devices are especially noteworthy due to their very low noise (0.05% rms from dc-2 MHz), sub 10 mrad beam pointing stability combined with small size, low power consumption (<10 W) and high efficiency.

  17. Ocular damage effects from 1338-nm pulsed laser radiation in a rabbit eye model

    PubMed Central

    Jiao, Luguang; Wang, Jiarui; Jing, Xiaomin; Chen, Hongxia; Yang, Zaifu

    2017-01-01

    The ocular damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, no retinal damage thresholds are determined in a wide interval between 0.65 ms and 80 ms, and a definite relationship between corneal damage threshold and spot size cannot be drawn from existing data points. In this paper, the in-vivo corneal damage thresholds (ED50s) were determined in New Zealand white rabbits for a single 5 ms pulse at the wavelength of 1338 nm for spot sizes from 0.28 mm to 3.55 mm. Meanwhile, the retinal damage threshold for this laser was determined in chinchilla grey rabbits under the condition that the beam was collimated, and the incident corneal spot diameter was 5.0 mm. The corneal ED50s given in terms of the corneal radiant exposure for spot diameters of 0.28, 0.94, 1.91, and 3.55 mm were 70.3, 35.6, 29.6 and 30.3 J/cm2, respectively. The retinal ED50 given in terms of total intraocular energy (TIE) was 0.904 J. The most sensitive ocular tissue to this laser changed from the cornea to retina with the increase of spot size. PMID:28663903

  18. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses

    NASA Astrophysics Data System (ADS)

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-07-01

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision.

  19. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses

    PubMed Central

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-01-01

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision. PMID:26173804

  20. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses.

    PubMed

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-07-15

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision.

  1. Power and radiance scaling of a 946 nm Nd:YAG planar waveguide laser

    NASA Astrophysics Data System (ADS)

    Ng, S. P.; Mackenzie, J. I.

    2012-03-01

    We present a diode-end-pumped Nd:YAG planar waveguide laser operating on neodymium's quasi-four-level transition at a wavelength of 946 nm. Two modes of operation are described: a high-power multi-mode monolithic cavity generating 105 for 210 W of incident pump power with a slope efficiency of ˜54%, and secondly, a high-radiance configuration employing an external stable resonator producing a maximum output power of 29.2 for 86.5 W of incident pump-power, with a slope efficiency of 33%. The output beam quality values of the external cavity were M2 of 3.2 by 2.4, leading to a maximum radiance of 0.43 GW cm-2 sr-1.

  2. Blue Up-Conversion Fibre Laser Pumped by a 1120-nm Raman Fibre Laser

    NASA Astrophysics Data System (ADS)

    Qin, Guan-Shi; Huang, Sheng-Hong; Feng, Yan; Shirakawa, A.; Musha, M.; Ueda, Ken-ichi

    2005-05-01

    A Tm3+-doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fibre up-conversion laser pumped by a 1120-nm Raman fibre laser is demonstrated with blue output power levels up to 116 mW. For the output mirror with 80% reflectivity, the slope efficiency is about 15%, the optical-to-optical conversion efficiency is 11%, and the maximum un-saturated output power is 116 mW. For 60% reflectivity, the slope efficiency is about 18% and the optical-to-optical conversion efficiency is 12%, whilst the maximum saturated output power is about 80 mW due to the existence of photo-degradation effect in Tm3+ doped ZBLAN glass fibre.

  3. Investigations of a Dual Seeded 1178 nm Raman Laser System

    DTIC Science & Technology

    2016-01-14

    nm Raman system was built and 20 W of 1178 nm output power was achieved with a polarization extinction ratio of 21 and nearly diffraction limited...power was achieved with a polarization extinction ratio of 21 and nearly diffraction limited beam quality. Linewidth broadening was found to...polarization extinction ratio of 30 dB was obtained and a 20 time’s reduction in the effective stimulated Brillouin scattering coefficient was

  4. Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

    PubMed Central

    Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

    2017-01-01

    We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ∼3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers. PMID:28322327

  5. Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

    NASA Astrophysics Data System (ADS)

    Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

    2017-03-01

    We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ∼3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers.

  6. Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range.

    PubMed

    Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

    2017-03-21

    We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ∼3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers.

  7. Stable 811.53 nm diode laser pump source for optically pumped metastable Ar laser

    NASA Astrophysics Data System (ADS)

    Gao, Jun; Zuo, Duluo; Zhao, Jun; Li, Bin; Yu, Anlan; Wang, Xinbing

    2016-10-01

    A stable external cavity diode laser coupled with volume Bragg grating for metastable argon atoms pumping is presented. The measured maximum output power of the continuous wave is 6.5 W when the spectral width (FWHM) is less than 21 pm around 811.53 nm and the power efficiency is 68%. The tuning range of the emission wavelength is bigger than 270 pm. The calculated deviation in relative absorption efficiency caused by the fluctuations of wavelength and power is less than 4%.

  8. Proposed SLR Optical Bench Required to Track Debris Using 1550 nm Lasers

    NASA Technical Reports Server (NTRS)

    Shappirio, M.; Coyle, D. B.; McGarry, J. F.; Bufton, J.; Cheek, J. W.; Clarke, G.; Hull, S. M.; Skillman, D. R.; Stysley, P. R.; Sun, X.; Young, R. P.; Zagwodzki, T.

    2015-01-01

    A previous study has indicated that by using approx.1550 nm wavelengths a laser ranging system can track debris objects in an "eye safe" manner, while increasing the expected return rate by a factor of approx. 2/unit area of the telescope. In this presentation we develop the optical bench required to use approx.1550nm lasers, and integration with a 532nm system. We will use the optical bench configuration for NGSLR as the baseline, and indicate a possible injection point for the 1550 nm laser. The presentation will include what elements may need to be changed for transmitting the required power on the approx.1550nm wavelength, supporting the alignment of the laser to the telescope, and possible concerns for the telescope optics.

  9. Compact Cr:ZnS Channel Waveguide Laser Operating at 2333 nm

    DTIC Science & Technology

    2014-03-24

    Okhrimchuk, V. Mezentsev, A. Shestakov, and I. Bennion, “Low loss depressed cladding waveguide inscribed in YAG:Nd single crystal by femtosecond laser ...demonstrated mid-infrared laser operation [2–5]. Chromium laser technology has matured to demonstrate high power, widely tunable, and narrow line- width ...the laser output was measured using a 300 mm monochromator (Gilden Photonics) capable of resolving a minimum line- width of 0.4 nm. The spectrum was

  10. Asymmetric, nonbroadened waveguide structures for double QW high-power 808nm diode laser

    NASA Astrophysics Data System (ADS)

    Abbasi, S. P.; Mahdieh, M. H.

    2017-01-01

    In this paper, we propose an asymmetric epitaxial layer structre for designing 808nm diode laser. In this asymmetric sructure, the p-waveguide is reduced in thickness and the p-cladding is doped for increasing the thermal conductivity and consequently better heat extraction. The main purpose of using such design is enhancing the laser gain by reduction of loss in laser cavity, and reduction of electrical and thermal resistivity of the diode laser.

  11. 532-nm laser sources based on intracavity frequency doubling of extended-cavity surface-emitting diode lasers

    NASA Astrophysics Data System (ADS)

    Shchegrov, Andrei V.; Umbrasas, Arvydas; Watson, Jason P.; Lee, Dicky; Amsden, Charles A.; Ha, Wonill; Carey, Glen P.; Doan, Vincent V.; Moran, Bryan; Lewis, Alan; Mooradian, Aram

    2004-07-01

    We introduce a novel type of cw green laser source, the Protera 532, based on the intracavity frequency doubling of an extended-cavity, surface-emitting diode laser. The distinguishing characteristics of this platform are high compactness and efficiency in a stable, single-longitudinal mode with beam quality M2 < 1.2. The laser design is based on the previously reported NECSEL architecture used for 488nm lasers, and includes several novel features to accommodate different types of nonlinear optical materials. The infrared laser die wavelength is increased from 976nm to 1064nm without compromising performance or reliability. The intracavity frequency doubling to 532nm has been demonstrated with both bulk and periodically poled nonlinear materials, with single-ended cw power outputs of greater than 30 mW.

  12. High-average-power narrow-line-width sum frequency generation 589 nm laser

    NASA Astrophysics Data System (ADS)

    Lu, Yanhua; Fan, Guobin; Ren, Huaijin; Zhang, Lei; Xu, Xiafei; Zhang, Wei; Wan, Min

    2015-10-01

    An 81 W average-power all-solid-state sodium beacon laser at 589 nm with a repetition rate of 250 Hz is introduced, which is based on a novel sum frequency generation idea between two high-energy, different line widths, different beam quality infrared lasers (a 1064 nm laser and a 1319 nm laser). The 1064 nm laser, which features an external modulated CW single frequency seed source and two stages of amplifiers, can provide average-power of 150 W, beam quality M2 of ~1.8 with ultra-narrow line width (< 100 kHz). The 1319 nm laser can deliver average-power of 100 W, beam quality M2 of ~3.0 with a narrow line width of ~0.3 GHz. By sum frequency mixing in a LBO slab crystal (3 mm x 12 mm x 50 mm), pulse energy of 325 mJ is achieved at 589 nm with a conversion efficiency of 32.5 %. Tuning the center wavelength of 1064 nm laser by a PZT PID controller, the target beam's central wavelength is accurately locked to 589.15910 nm with a line width of ~0.3 GHz, which is dominated mainly by the 1319 nm laser. The beam quality is measured to be M2 < 1.3. The pulse duration is measured to be 150 μs in full-width. To the best of our knowledge, this represents the highest average-power for all-solid-state sodium beacon laser ever reported.

  13. Two-level laser: Analytical results and the laser transition

    SciTech Connect

    Gartner, Paul

    2011-11-15

    The problem of the two-level laser is studied analytically. The steady-state solution is expressed as a continued fraction and allows for accurate approximation by rational functions. Moreover, we show that the abrupt change observed in the pump dependence of the steady-state population is directly connected to the transition to the lasing regime. The condition for a sharp transition to Poissonian statistics is expressed as a scaling limit of vanishing cavity loss and light-matter coupling, {kappa}{yields}0, g{yields}0, such that g{sup 2}/{kappa} stays finite and g{sup 2}/{kappa}>2{gamma}, where {gamma} is the rate of nonradiative losses. The same scaling procedure is also shown to describe a similar change to the Poisson distribution in the Scully-Lamb laser model, suggesting that the low-{kappa}, low-g asymptotics is of more general significance for the laser transition.

  14. High-order harmonic generation from plasma plume pumped by 400 nm wavelength laser

    SciTech Connect

    Ganeev, Rashid A.; Elouga Bom, Luc B.; Ozaki, Tsuneyuki

    2007-09-24

    The authors present their study on high-order harmonic generation pumped by 400 nm wavelength laser from plasma plumes produced on the surfaces of various solid-state targets. The maximum harmonic cutoff was observed for Be plasma (31st harmonic, {lambda}=12.9 nm). They compared these results with harmonic generation pumped by 800 nm wavelength laser. The authors demonstrated single harmonic enhancement for Cr, Sn, Sb, and Mn plasmas. They also studied the use of varying the chirp of the pump laser to control the enhancement of single harmonics within the plateau.

  15. 1059 and 1328nm LD pumped Nd:S-FAP solid state laser

    SciTech Connect

    Sun Lianke; Zhang Shaojun; Zhao Shengzhi; Wang Qingpu

    1996-12-31

    In this paper the authors introduce a new laser crystal--Nd{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F, Nd:S-FAP, and present its optical and physical characteristics. Based on the experiment lasing performance of CW LD pumped Nd:S-FAP crystal is reported here: the threshold and slope efficiency of 1059 nm Nd:S-FAP laser pumped by CW LD at 805nm are 7mW and 41%, and that of 1328nm Nd:S-FAP laser are 19mW and 35%. The comparison between experimental result and theoretical calculation is also discussed in this paper.

  16. Monolithic 626 nm single-mode AlGaInP DBR diode laser.

    PubMed

    Blume, G; Nedow, O; Feise, D; Pohl, J; Paschke, K

    2013-09-09

    Single-mode lasers below 630 nm are still realized using complex laser systems. We present distributed Bragg reflector (DBR) ridge waveguide lasers (RWL) based on AlGaInP. When packaged into sealed TO-3 housings and cooled internally to about 0°C the DBR-RWL emit more than 50 mW at a wavelength of 626.0 nm into a nearly diffraction-limited single longitudinal mode with a spectral width below 1 MHz. These new monolithic diode lasers have the potential to drastically miniaturize existing set-ups e.g. for quantum information processing.

  17. Differential Gene Expression in Explanted Human Retinal Pigment Epithelial Cells 24-Hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser Light and 1064 nm, 170 ps Pulsed Laser Light 12-Hours Post-Exposure: Results Compendium

    DTIC Science & Technology

    2004-06-01

    Laser Light and 1064 nm, 170 ps Pulsed Laser Light 12-hours Post-Exposure: Results Compendium John W. Obringer Martin D. Johnson Laser and Optics...Explanted Human Retinal Pigment Epithelial Cells 12-hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser Light and 1064 nm, 170 ps Pulsed Laser Lightl2-hours...Explanted Human Retinal Pigment Epithelial USAFA F05611-02-P-0471 Cells 24-Hours Post-Exposure to 532 nm, 3.0 ns Pulsed Laser-Light and 1064nm, 170 ps Pulsed

  18. Treatment of keloid scars with a 1210-nm diode laser in an animal model.

    PubMed

    Philandrianos, Cécile; Bertrand, Baptiste; Andrac-Meyer, Lucile; Magalon, Guy; Casanova, Dominique; Kerfant, Nathalie; Mordon, Serge

    2015-12-01

    A temperature increase can improve wound healing by activation of heat shock protein 70 and stimulation of fibroblasts. Since keloids are a dysfunction of collagen fiber synthesis and organization, this study aimed to evaluate if a 1,210 nm diode laser could have effects in a new animal model of keloid scars. A total of 39 nude mice were used for this study. Phototypes IV and V human keloids were grafted into their backs and after 1 month of healing, the mice were divided into four groups: Control, Laser, Resection, Resection/Laser. In the Laser group, the keloids were treated with a 1,210-nm diode-laser with the following parameters: 4 W; 10 seconds; fluence: 51 J/cm(2) ; spot: 18.9 × 3.7 mm(2) . In the Resection group, surgical intra-lesional excision was performed. In the Resection/Laser group, keloids were treated with the 1,210-nm laser-diode after surgical intra-lesional excision. Temperature measurements were made during the laser treatment. Clinical examination and histological study were performed on the day of treatment and 1 month, 2 months, and 3 months later. Mean temperature measurement was of 44.8°C (42-48°) in the Laser groups. No healing complications or keloid proliferation was observed in any group. Keloid histologic characters were confirmed in all grafts. No histologic particularity was observed in the laser groups in comparison with the Control and Resection groups. First, this keloid animal model appears to be adapted for laser study. Secondly, the 1,210-nm diode laser does not induce keloid thermal damage in vivo. Further studies with different 1,210-nm laser diode parameters should be performed in order to observe significant effects on keloids. © 2015 Wiley Periodicals, Inc.

  19. All-solid-state parametric Raman anti-Stokes laser at 508 nm.

    PubMed

    Mildren, R P; Coutts, D W; Spence, D J

    2009-01-19

    We report a parametric anti-Stokes Raman laser using potassium gadolinium tungstate, generating output chiefly at the first anti-Stokes at 508 nm. The compact 4.5 cm long device is pumped by a Q-switched 532 nm laser and uses an off-axis Stokes resonator to provide non-collinear phase matching between the pump and the generated Stokes and anti-Stokes fields. Anti-Stokes output energies up 0.27 mJ were obtained at a conversion efficiency from the pump of 0.46%. Second- and third-order anti-Stokes lines at 486 nm and 465 nm were also observed.

  20. 1016nm all fiber picosecond MOPA laser with 50W output.

    PubMed

    Qi, Xue; Chen, Sheng-Ping; Sun, Hai-Yue; Yang, Bing-Ke; Hou, Jing

    2016-07-25

    This paper presents an all fiber high power picosecond laser at 1016 nm in master oscillator power amplifier (MOPA) configuration. A direct amplification of this seed source encounters obvious gain competition with amplified spontaneous emission (ASE) at ~1030 nm, leading to a seriously reduced amplification efficiency. To suppress the ASE and improve the amplification efficiency, we experimentally investigate the influence of the gain fiber length and the residual ASE on the perforemance of the 1016 nm amplifier. The optimized 1016 nm MOPA laser exhibits an average power of 50 W and an optical conversion efficiency of 53%.

  1. Research on 9xx nm diode laser for direct and pumping applications

    NASA Astrophysics Data System (ADS)

    Sebastian, J.; Hülsewede, R.; Pietrzak, A.; Zorn, M.; Wölz, M.; Meusel, J.; Schröder, M.; Wittschirk, Th.

    2015-02-01

    High-power laser bars and single emitters have proven as attractive light sources for many industrial applications such as direct material processing or as pump sources for solid state and fiber-lasers. There is also a great interest in quasi-CW laser bars for high-energy projects. These applications require a continuous improvement of laser diodes for reliable optical output powers, high electrical-to-optical efficiencies, brightness and costs. In this paper JENOPTIK presents an overview of recent research for highly efficient CW and quasi-CW laser devices emitting in a wide wavelength range between 880 nm and 1020 nm. The last research results concern the 9xx single emitters and laser arrays. The 9xx nm 12 W single emitters and 976 nm 55 W laser arrays have efficiencies above 65%. New life time tests for single emitter devices currently exceed 1300 hours of reliable operation at room temperature and over 1500 hours at 45°C. Because of the small far field distribution of the optical power, the high output power and the small near field the 55 W arrays show a brightness of 75 MW x cm-2sr-1 with 95% power content. The technology for new generation 940 nm high fill-factor bars has been currently extended to emission wavelengths of 976 nm and 1020 nm with excellent results: 200 W output power with 63% efficiency using passive cooling. The innovative design of the laser structure enables, moreover, the realization of 500 W 880 nm quasi-CW laser bars with wall-plug efficiencies of 55% and a narrow fast-axis divergence angle of 40° (95% power content).

  2. Measurement of the Yb I S10-P11 transition frequency at 399 nm using an optical frequency comb

    NASA Astrophysics Data System (ADS)

    Kleinert, Michaela; Gold Dahl, M. E.; Bergeson, Scott

    2016-11-01

    We determine the frequency of the Yb I S10-P11 transition at 399 nm using an optical frequency comb. Although this transition was measured previously using an optical transfer cavity [D. Das et al., Phys. Rev. A 72, 032506 (2005), 10.1103/PhysRevA.72.032506], recent work has uncovered significant errors in that method. We compare our result of 751 526 533.49 ± 0.33 MHz for the 174Yb isotope with those from the literature and discuss observed differences. We verify the correctness of our method by measuring the frequencies of well-known transitions in Rb and Cs, and by demonstrating proper control of systematic errors in both laser metrology and atomic spectroscopy. We also demonstrate the effect of quantum interference due to hyperfine structure in a divalent atomic system and present isotope shift measurements for all stable isotopes.

  3. Laser Manipulation of Nuclear Transitions

    DTIC Science & Technology

    2008-04-14

    Pyataev, The interactions of Mössbauer photons with nuclei showing nonlinear spins dynamics. Proceedings of II International conference "Frontiers of... Nonlinear Physics", ed. Litvak A., Nizny-Novgorod, 2005, p.482-486 9. F.G. Vagizov, R.L. Kolesov, O.A. Kocharovskaya, Laser-induced transformations of...57Fe:MgO Mössbauer spectrum, Proceedings of II International conference "Frontiers of Nonlinear Physics",-ed. Litvak A.,Nizny-Novgorod, 2005, p.505

  4. Mechanisms of the blue emission of NaYF4:Tm(3+) nanoparticles excited by an 800 nm continuous wave laser.

    PubMed

    Zhang, Hongxin; Jia, Tianqing; Shang, Xiaoying; Zhang, Shian; Sun, Zhenrong; Qiu, Jianrong

    2016-10-07

    A thorough understanding of energy transfer and upconversion (UC) processes between trivalent lanthanide (Ln(3+)) ions is essential and important for improving UC performance. However, because of the abundant energy states of Ln(3+) ions, UC mechanisms are very complicated, which makes it a challenge to exclusively verify and quantitatively evaluate the dominant process. In this study, the fundamental excitation processes of Tm(3+)-doped NaYF4 nanocrystals under 800 nm continuous wave (CW) laser excitation were experimentally investigated on the basis of the quantum transition principle. An 800 nm CW laser combined with other wavelength CW lasers, including 471 nm, 657 nm, 980 nm, and 1550 nm lasers, were designed to study in-depth the excitation processes of UC luminescence via simultaneous two-wavelength laser excitation. The results indicate that the excited state absorption of (3)H6→(3)H4∼∼(3)H5→(1)G4 is the dominant pathway of the 481 nm and 651 nm emission bands, and two kinds of energy transfer UC pathways, uniformly expressed as (1)G4 + (3)H4→(1)D2 + (3)F4, play the primary roles in the 456 nm emission band.

  5. Treatment of onychomycosis using a submillisecond 1064-nm neodymium:yttrium-aluminum-garnet laser.

    PubMed

    Carney, Caitlin; Cantrell, Wendy; Warner, Judy; Elewski, Boni

    2013-10-01

    Laser treatment has emerged as a novel treatment modality for onychomycosis. We sought to determine thermal response and optical effects of a submillisecond neodymium:yttrium-aluminum-garnet (Nd:YAG) 1064-nm laser on common fungal nail pathogens, and the clinical efficacy and safety of the Nd:YAG 1064-nm laser on onychomycotic toenails. A 4-part in vitro and in vivo study was conducted using a Nd:YAG 1064-nm laser. The first portion evaluated 3 different nail pathogens in suspension at 7 heat and time exposures. The second and third parts of the study irradiated pure fungal colonies. The final portion involved an in vivo treatment of toenails over 5 treatment sessions. A fungicidal effect for Trichophyton rubrum was seen at 50°C after 15 minutes, and for Epidermophyton floccosum at 50°C after 10 minutes. Limited growth of Scytalidium was seen at 55°C after 5 minutes. No inhibition was observed after laser treatment of fungal colonies or suspensions. In vivo treatment of toenails showed no improvement in Onychomycosis Severity Index score. The Nd:YAG 1064-nm laser was the only laser tested. Laser treatment of onychomycosis was not related to thermal damage or direct laser effects. In vivo treatment did not result in onychomycosis cure. Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  6. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  7. High efficient photovoltaic power converter suitable for 920nm to 970nm InGaAs laser diodes

    NASA Astrophysics Data System (ADS)

    Liu, James; Wu, Ta-Chung; Cohen, Mort; Werthen, Jan G.

    2005-09-01

    In this work, we report a highly efficient Photovoltaic Power Converter (PPC) suitable for 920 nm to 970 nm InGaAs MQW lasers for the first time. The epitaxial layers were grown by low pressure MOCVD on the semi-insulting GaAs substrate. The epi layers consist of a p-n junction of In0.12Ga0.88As and the window layer of p+ AlInGaAs. The device is made of seven or eight pie-segments of equal area series-connected by means of air-bridges. Under 500mW of 940nm laser illumination, the open-circuit voltage of the eight-segment InGaAs chip is 6.7V. The short-circuit current is 29.7mA. Its maximum delivered electrical power is 171.2mW, equal to a 34.2% overall power conversion efficiency. We also demonstrate the high temperature characteristic and stability of the device.

  8. Generation of coherent 19- and 38-nm radiation at a free-electron laser directly seeded at 38 nm.

    PubMed

    Ackermann, S; Azima, A; Bajt, S; Bödewadt, J; Curbis, F; Dachraoui, H; Delsim-Hashemi, H; Drescher, M; Düsterer, S; Faatz, B; Felber, M; Feldhaus, J; Hass, E; Hipp, U; Honkavaara, K; Ischebeck, R; Khan, S; Laarmann, T; Lechner, C; Maltezopoulos, Th; Miltchev, V; Mittenzwey, M; Rehders, M; Rönsch-Schulenburg, J; Rossbach, J; Schlarb, H; Schreiber, S; Schroedter, L; Schulz, M; Schulz, S; Tarkeshian, R; Tischer, M; Wacker, V; Wieland, M

    2013-09-13

    Initiating the gain process in a free-electron laser (FEL) from an external highly coherent source of radiation is a promising way to improve the pulse properties such as temporal coherence and synchronization performance in time-resolved pump-probe experiments at FEL facilities, but this so-called "seeding" suffers from the lack of adequate sources at short wavelengths. We report on the first successful seeding at a wavelength as short as 38.2 nm, resulting in GW-level, coherent FEL radiation pulses at this wavelength as well as significant second harmonic emission at 19.1 nm. The external seed pulses are about 1 order of magnitude shorter compared to previous experiments allowing an ultimate time resolution for the investigation of dynamic processes enabling breakthroughs in ultrafast science with FELs. The seeding pulse is the 21st harmonic of an 800-nm, 15-fs (rms) laser pulse generated in an argon medium. Methods for finding the overlap of seed pulses with electron bunches in spatial, longitudinal, and spectral dimensions are discussed and results are presented. The experiment was conducted at FLASH, the FEL user facility at DESY in Hamburg, Germany.

  9. Continuous wave Nd:YAG-BiBO blue laser under direct 869 nm pumping

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    We report a blue laser at 473 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 946 nm Nd:YAG laser under in-band diode pumping at 869 nm. An BiBO 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 8.6 W, as high as 721 mW of CW output power at 473 nm is achieved. The optical-to-optical conversion efficiency is up to 8.4%, and the fluctuation of the blue output power was better than 3.5% in the given 30 min.

  10. Combination of 595-nm pulsed dye laser, long-pulsed 755-nm alexandrite laser, and microdermabrasion treatment for keratosis pilaris: retrospective analysis of 26 Korean patients.

    PubMed

    Lee, Sang Ju; Choi, Min Ju; Zheng, Zhenlong; Chung, Won Soon; Kim, Young Koo; Cho, Sung Bin

    2013-06-01

    Keratosis pilaris (KP) has beenpresented as small keratotic follicular papules with or without surrounding erythema. Various treatments with laser or light therapy have been used for the management of KP with various clinical outcomes. In the present study, we investigated the efficacy and safety of a combination therapy for KP. A total of 29 anatomical sites with KP in 26 patients were treated using a 595-nm pulsed dye laser (PDL) with nonpurpuragenic fluences, a long-pulsed 755-nm alexandrite laser, and microdermabrasion. Clinical improvement was assessed by comparing preand posttreatment clinical photographs and patient satisfaction rates. Evaluation of the clinical results three months after the treatments showed that 12 of the 29 anatomical sites (41.4%) demonstrated Grade 3 clinical improvement, ten (34.5%) had Grade 2 clinical improvement, four (13.8%) showed Grade 1 improvement, and three (10.3%) showed Grade 4 improvement. We observed that KP lesions improved not only in erythema and skin texture, but also in brownish dyschromias. Potential adverse events were not observed, except prolonged posttherapy scaling. Our observations demonstrate that combination therapy using a 595-nm PDL, a long-pulsed 755-nm alexandrite laser, and microdermabrasion can have a positive therapeutic effect on KP.

  11. Note: Deep ultraviolet Raman spectrograph with the laser excitation line down to 177.3 nm and its application

    SciTech Connect

    Jin, Shaoqing; Fan, Fengtao; Guo, Meiling; Zhang, Ying; Feng, Zhaochi E-mail: canli@dicp.ac.cn; Li, Can E-mail: canli@dicp.ac.cn

    2014-04-15

    Deep UV Raman spectrograph with the laser excitation line down to 177.3 nm was developed in this laboratory. An ellipsoidal mirror and a dispersed-subtractive triple monochromator were used to collect and disperse Raman light, respectively. The triple monochromator was arranged in a triangular configuration with only six mirrors used. 177.3 nm laser excited Raman spectrum with cut-off wavenumber down to 200 cm{sup −1} and spectral resolution of 8.0 cm{sup −1} can be obtained under the condition of high purity N{sub 2} purging. With the C–C σ bond in Teflon selectively excited by the 177.3 nm laser, resonance Raman spectrum of Teflon with good quality was recorded on the home-built instrument and the σ-σ{sup *} transition of C–C bond was studied. The result demonstrates that deep UV Raman spectrograph is powerful for studying the systems with electronic transition located in the deep UV region.

  12. Role of excited state photoionization in the 852.1 nm Cs laser pumped by Cs-Ar photoassociation

    SciTech Connect

    Hewitt, J. D.; Houlahan, T. J. Jr.; Eden, J. G.; Gallagher, J. E.; Perram, G. P.; Carroll, D. L.; Palla, A. D.; Verdeyen, J. T.

    2013-03-18

    Photoionization of Cs (6p {sup 2}P{sub 3/2}) atoms during the operation of a Cs D{sub 2} line (852.1 nm: 6p {sup 2}P{sub 3/2}{yields}6s {sup 2}S{sub 1/2}) laser, pumped by free{yields}free transitions of thermal Cs-Ar ground state pairs, has been investigated experimentally and computationally. Photoexcitation of Cs vapor/Ar mixtures through the blue satellite of the D{sub 2} transition (peaking at 836.7 nm) selectively populates the {sup 2}P{sub 3/2} upper laser level by the dissociation of the CsAr excited complex. Comparison of laser output energy data, for instantaneous pump powers up to 3 MW, with the predictions of a numerical model sets an upper bound of 8 Multiplication-Sign 10{sup -26} cm{sup 4} W{sup -1} on the Cs (6p {sup 2}P{sub 3/2}) two photon ionization cross-section at 836.7 nm which corresponds to a single photon cross-section of 2.4 Multiplication-Sign 10{sup -19} cm{sup 2} for a peak pump intensity of 3 MW cm{sup -2}.

  13. 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

  14. Characterization, diagnosis and ablation of human teeth using blue laser at 457 nm

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ashraf F.; Gomaa, Walid; El-Sharkawy, Yasser H.

    2014-02-01

    The light interaction with tissue is governed by the specific wavelength of the laser used and the optical properties of target tissue. Absorption, scattering and fluorescence together can probably be used as the basis of quantitative diagnostic methods for teeth caries. The absorption coefficient of human teeth was determined from detached wet teeth (incisors and premolars). Laser absorption of these teeth was measured using compact blue laser source at wavelength of 457 nm and a high resolution spectrometer equipped with an integrating sphere. The average absorption coefficient of abnormal caries tissue of human teeth is observed to be higher than the normal ones. Detection and diagnosis of caries tissues were monitored by high resolution translational scanning of human teeth. We have a powerful tool to diagnosis a caries region of human teeth using blue laser at 457 nm. Ablations of caries region are investigated using higher power of blue laser at 457 nm.

  15. A laser ranging system operating at 1036 nm with Geiger-mode silicon avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Wu, Guang; Ren, Min; Liang, Yan; Wang, Zhiyuan; Pan, Haifeng; Zeng, Heping

    2012-09-01

    We demonstrated a laser ranging experiment obtained with a Geiger-mode silicon avalanche photodiode (Si GAPD). The Surface-to-surface resolution of 15 cm was achieved with the technique of time-correlated single-photon counting. In the experiment, a mode-locked Yb-doped fiber laser at 1036 nm was applied, as the detection efficiency at 1036 nm of Si GAPDs is much higher than that at 1064nm which was widely applied in remote sensing. Due to the single-photon detector, the laser ranging system was able to measure the reflected photon pulses at single-photon level. We realized 32- m laser ranging experiment with a 135-mm diameter Newtonian telescope in daylight. And the system could measure the non-cooperated object longer than 11.3 km far away, which was tested through inserting the optical loss. It presented a potential for hundreds-of-kilometer laser ranging at low-light level.

  16. Continuous-wave yellow laser generation at 578 nm by intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Ma, Gangfei; Yang, Jianming; Tan, Huiming; Tian, Yubing; Yao, Wenming; Ju, Qiaojun; Zhang, Long; Chen, Jiansheng; Wu, Xiaodong; Gao, Jing

    2017-07-01

    We report a continuous-wave yellow laser at 578 nm obtained by doubly resonant intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser with a LBO nonlinear crystal. Single-wavelength laser operation at 578 nm by using a silica etalon as a wavelength selector and dual-wavelength operation at 578 nm and 582 nm are obtained with maximum output powers of 100 mW and 136 mW, respectively. The single wavelength operating power stability value in 30 min was 4.7%, which was improved ∼21.6%, compared with that of dual-wavelength operation.

  17. Compact and efficient CW 473nm blue laser with LBO intracavity frequency doubling

    NASA Astrophysics Data System (ADS)

    Qi, Yan; Wang, Yu; Wang, Yanwei; Zhang, Jing; Yan, Boxia

    2016-10-01

    With diode end pumped Nd:YAG directly and LBO intracavity frequency doubling, a compact, high efficient continuous wave blue laser at 473nm is realized. When the incident pump power reach 6.2W, 630mW maximum output power of blue laser at 473nm is achieved with 15mm long LBO, the optical-to-optical conversion efficiency is as high as 10.2%.

  18. Diode pumped Nd:GSAG and Nd:YGG laser at 942 and 935 nm

    NASA Astrophysics Data System (ADS)

    Strohmaier, S. G. P.; Eichler, H. J.; Czeranowsky, C.; Ileri, B.; Petermann, K.; Huber, G.

    2007-07-01

    Two new Nd 3+ doped crystals show laser activity between the 4F 3/2 and 4I 9/2 levels. Diode pumped emission of Nd:GSAG at 942 nm wavelength with 950 mW output power and 14% optical to optical efficiency as well as laser emission of Nd:YGG at 935 nm with 700 mW output power and 11% efficiency have been obtained. These wavelengths are useful for water vapour absorption measurements.

  19. Theoretical and experimental research on the ˜980-nm Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Wang, Yanshan; Ke, Weiwei; Ma, Yi; Sun, Yinhong; Feng, Yujun

    2016-07-01

    The output properties of the ˜980-nm Yb-doped fiber laser versus pump power and core-cladding ratio of gain fiber, also the amplified spontaneous emission (ASE) at different wavelengths of seed laser, are investigated theoretically. An all-fiber amplifier based on different wavelengths of seed laser at 974.4, 977, and 981.7 nm brings the studies on parasitic oscillation and ASE in the ˜980-nm Yb-doped fiber amplifier. Through the theoretical and experimental research, we found that the controlling of three-level ASE around ˜980-nm is pivotal for obtaining a high-power 980-nm Yb-doped fiber amplifier.

  20. Linewidth characteristics of Raman-shifted dye laser output at 720 and 940 nm

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Higdon, N. S.; Higdon, N. S.; Higdon, N. S.; Higdon, N. S.; Higdon, N. S.; Higdon, N. S.

    1986-01-01

    Existing DIAL systems for water vapor measurements in the troposphere operate at wavelengths near 720 nm. The use of stronger water vapor absorption lines in the range 930 to 960 nm will significantly improve DIAL measurements in the upper troposphere and lower stratosphere where water vapor concentrations are low. The generation of light at 940 nm using a frequency doubled Nd:YAG pumped dye laser is inefficient due to the small absorption if infrared dyes at the pump wavelength. However, 940 nm generation utilizing stimulated Raman scattering of dye lasers is attractive because of a potentially high conversion efficiency plus the possibility of retaining the narrow linewidth available from some dye lasers. The Raman conversion efficiency and line broadening are presented for first Stokes operation at 720 and 940 nm using hydrogen and deuterium as the Raman media.

  1. All solid-state 191.7 nm deep-UV light source by seventh harmonic generation of an 888 nm pumped, Q-switched 1342 nm Nd:YVO₄ laser with excellent beam quality.

    PubMed

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

    2014-06-02

    In this paper we report on the realization of a deep-UV light source using the 1.3 μm transition of neodymium as pumping wavelength. The 191.7 nm radiation was obtained by generating the seventh harmonic of a high-power Q-switched 1342 nm Nd:YVO4 laser. A cesium lithium borate crystal was used for sum frequency mixing of the sixth harmonic and the fundamental. With a total of four conversion stages, up to 240 mW were achieved, with excellent beam quality at 155 mW (M2 < 1.7) and 190 mW (M2 < 1.9).

  2. Dual-wavelength waveguide lasers at 1064 and 1079 nm in Nd:YAP crystal by direct femtosecond laser writing.

    PubMed

    Nie, Weijie; Cheng, Chen; Jia, Yuechen; Romero, Carolina; Vázquez de Aldana, Javier R; Chen, Feng

    2015-05-15

    Low-loss depressed cladding waveguides have been produced in Nd:YAP laser crystal by using direct femtosecond laser writing. Under optical pump at 812 nm at room temperature, continuous-wave simultaneous dual-wavelength laser oscillations at 1064 and 1079 nm, both along TM polarization, have been realized in the waveguiding structures. It has been found that, with the variation of pump polarization, the intensity ratio of 1064 and 1079 nm emissions varies periodically, while the polarization of output dual-wavelength laser remains unchanged. The maximum output power achieved for the Nd:YAP waveguide lasers is ∼200  mW with a slope efficiency of 33.4%.

  3. Ruby Emission in the Range 400-800 nm with Excitation by Continuous-Wave CO2 Laser Pulses

    NASA Astrophysics Data System (ADS)

    Marchenko, V. M.; Kiselev, V. V.

    2017-01-01

    Thermal emission spectra of ruby single crystals in the range 400-800 nm were studied experimentally as functions of the intensity at 10.6 μm of exciting pulses ( 0.5 s) from a continuous-wave electrical-discharge CO2 laser. Spectra at excitation intensity 1-20 kW/cm2 were superpositions of the thermal emission continuum of the sapphire crystal lattice in the range 600-800 nm and selective emission spectra of Cr3+ that were observed for the first time for ruby and consisted of R-lines at 695 nm; N-lines at 715 nm; 2 T 1, 4 T 2 → 4 A 2 transition bands at 672 and 643 nm; and 4 T 1, 2 T 2 → 4 A 2 transition bands at 530 and 490 nm that were not observed in the luminescence spectrum. Time dependences of the shapes of selective emission spectra, quenching and shifts of the R 1 line, and the temperature dependence of ruby luminescence spectra were investigated.

  4. Single-frequency tunable 447.3 nm laser by frequency doubling of tapered amplified diode laser at cesium D1 line.

    PubMed

    Zhang, Yan; Liu, Jinhong; Wu, Jinze; Ma, Rong; Wang, Dan; Zhang, Junxiang

    2016-08-22

    A continuous single-frequency tunable blue laser at 447.3 nm is developed by external-cavity frequency doubling of a tapered amplifier-boosted continuous-wave diode laser at cesium (Cs) D1 line. A maximum blue power of 178 mW with 50.8% conversion efficiency is obtained. It can be continuously tuned over a range around 1.6 GHz as the diode laser frequency is scanned across the F=4→F'=3 transition of 133Cs D1 line. The generated tunable and stable blue laser source has potential applications in constructing quantum light-atom interfaces in quantum networks.

  5. Performance and reliability of high power 7xx nm laser diodes

    NASA Astrophysics Data System (ADS)

    Bao, Ling; Wang, Jun; Devito, Mark; Xu, Dapeng; Grimshaw, Mike; Dong, Weimin; Guan, Xingguo; Huang, Hua; Leisher, Paul; Zhang, Shiguo; Wise, Damian; Martinsen, Robert; Haden, Jim

    2011-02-01

    High power diode lasers in 7xx-nm region, have been needed for various applications. Compared to 9xx nm lasers that have been developed extensively in the last 20 years, high power lasers at 7xx-nm region presents much more challenges for operation power, efficiency, temperature performance and reliability. This paper will present recent progresses on 7xx nm laser diodes for the above attributes. Two laser designs will be reviewed and high power diode laser performance and reliability will be presented. Single emitter devices, with 200μm wide emitting width, show up to 10W reliable operation power, with peak efficiency more than 65%. Accelerated life testing at 12A, 50°C heatsink temperature has been running for thousands of hours. High temperature performance and high COMD threshold (> 20W) will also be shown. Life-test failure modes will also be discussed. In summary, with advanced epitaxial structure design and MOCVD process, critical facet passivation and advanced heatsink and bonding technology, 7xx-8xx nm devices have been demonstrated with high performance and reliability similar to those of 9xx nm devices.

  6. Atomic force microscopy analysis of human cornea surface after UV (λ=266 nm) laser irradiation

    NASA Astrophysics Data System (ADS)

    Spyratou, E.; Makropoulou, M.; Moutsouris, K.; Bacharis, C.; Serafetinides, A. A.

    2009-07-01

    Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.

  7. Sub-70 nm resolution tabletop microscopy at 13.8 nm using a compact laser-plasma EUV source.

    PubMed

    Wachulak, Przemyslaw W; Bartnik, Andrzej; Fiedorowicz, Henryk

    2010-07-15

    We report the first (to our knowledge) demonstration of a tabletop, extreme UV (EUV) transmission microscope at 13.8 nm wavelength with a spatial (half-pitch) resolution of 69 nm. In the experiment, a compact laser-plasma EUV source based on a gas puff target is applied to illuminate an object. A multilayer ellipsoidal mirror is used to focus quasi-monochromatic EUV radiation onto the object, while a Fresnel zone plate objective forms the image. The experiment and the spatial resolution measurements, based on a knife-edge test, are described. The results might be useful for the realization of a compact high-resolution tabletop imaging systems for actinic defect characterization.

  8. Gratings, photosensitivity, and poling in silica optical waveguides with 157-nm fluorine laser radiation

    NASA Astrophysics Data System (ADS)

    Chen, Peng (Kevin)

    2002-08-01

    The energetic 7.9-eV photons of the F2 laser directly access bandgap states in germanosilicate glasses to drive one-photon processes for inducing strong refractive index changes in silica optical waveguides. In this thesis, the author carried out the first comprehensive F2-laser photosensitivity studies with an aim to assess prospects for shaping useful photonic structures directly inside the germanosilicate waveguides. Both planar waveguides and standard telecommunication fibers were examined. Large effective index change (>10-3) was induced in both fibers and planar waveguides without any enhancement technique. With the use of hydrogen loading enhancement, asymmetric refractive index profiles were noted by atomic force microscopy and microreflection microscopy, having a peak index change of larger than 0.01 in the fiber core. The 157-nm laser radiation is effective in rapidly forming long-period gratings in standard fibers. Grating formation is over 250 times faster than that with the 248-nm KrF laser constituting the fastest photosensitivity response ever reported. For planar lightwave circuits (PLCs), the 157-nm laser exposure generate narrow profiles of large index changes (Deltan ˜ 10 -2) that is useful in trimming phase errors and controlling birefringence in frequency domain modulators (FDMs) and interleavers. The large vacuum-ultraviolet-induced birefringence was used to completely compensate the intrinsic birefringence of Deltan ˜ 10-4 in typical PLCs. With hydrogen soaking, modest 157-nm pre-irradiation (accumulated fluence >3 J/cm2) was found to 'lock-in' a permanent photosensitivity enhancement in the germanosilica, permitting the formation of strong (40 dB) and stable fiber Bragg gratings with 248-nm-KrF laser light. The F2-laser photosensitivity locking was 300-time more effective than with KrF-laser pretreatment. The practical trimming applications in PLCs were demonstrated in PLC interleavers and FDMs. The 157-nm laser pre-radiation was found to

  9. Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta

    PubMed Central

    Park, Sang Woong; Shin, Kyung Chul; Park, Hyun Ji; Lee, In Wha; Kim, Hyung-Sik; Chung, Soon-Cheol; Kim, Ji-Sun; Jun, Jae-Hoon; Kim, Bokyung; Bae, Young Min

    2015-01-01

    The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca2+ channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms. PMID:26417517

  10. High-repetition-rate ultranarrow-bandwidth 193-nm excimer lasers for DUV lithography

    NASA Astrophysics Data System (ADS)

    Stamm, Uwe; Paetzel, Rainer; Bragin, Igor; Kleinschmidt, Juergen; Lokai, Peter; Osmanov, Rustem; Schroeder, Thomas; Sprenger, Martin; Zschocke, Wolfgang

    2000-07-01

    Results on the feasibility of highest repetition rate ArF lithography excimer lasers with narrow spectral bandwidth of less than 0.4 pm are presented. The current 193 nm lithography laser product NovaLine A2010 delivers output power of 10W at 2 kHz repetition rate with energy dose stability of +/- 0.5 percent. A novel 193 nm absolute wavelength calibration technique has ben incorporated in the laser which gives absolute wavelength accuracy better than 0.5 pm. Long-term results of optical materials, coatings and laser components give insight into estimated cost of ownership developments for the laser operation over the next years. Progress in pulse stretching approaches to achieve lower stress of the wafer scanner illumination optics and lens allow optimistic estimates of total system CoO. Initial results on the laser operation at 4 kHz in order to reach 20W output power are discussed.

  11. Study on damage of K9 glass under 248nm ultraviolet pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Fang, Xiaodong

    2015-04-01

    The damage of K9 glass under 248nm ultraviolet pulsed laser irradiation was studied. The laser pulse energy was kept within the range of 60mJ to 160mJ, and the repetition rate was adjusted within the range of 1Hz to 40Hz. The damage morphologies of single-pulse and multi-pulse laser irradiation were characterized by optical microscope, and the damage mechanism was discussed. The experimental results indicated that the damage of K9 glass irradiated by 248nm ultraviolet laser mainly followed the thermal-mechanical coupling mechanism and the damage threshold of K9 glass was 2.8J/cm2. The intensity of damage area increased gradually with the increase of the laser pulse number. It was shown that accumulation effect of laser induced damage to K9 glass was obvious.

  12. High reliability level on single-mode 980nm-1060 nm diode lasers for telecommunication and industrial applications

    NASA Astrophysics Data System (ADS)

    Van de Casteele, J.; Bettiati, M.; Laruelle, F.; Cargemel, V.; Pagnod-Rossiaux, P.; Garabedian, P.; Raymond, L.; Laffitte, D.; Fromy, S.; Chambonnet, D.; Hirtz, J. P.

    2008-02-01

    We demonstrate very high reliability level on 980-1060nm high-power single-mode lasers through multi-cell tests. First, we show how our chip design and technology enables high reliability levels. Then, we aged 758 devices during 9500 hours among 6 cells with high current (0.8A-1.2A) and high submount temperature (65°C-105°C) for the reliability demonstration. Sudden catastrophic failure is the main degradation mechanism observed. A statistical failure rate model gives an Arrhenius thermal activation energy of 0.51eV and a power law forward current acceleration factor of 5.9. For high-power submarine applications (360mW pump module output optical power), this model exhibits a failure rate as low as 9 FIT at 13°C, while ultra-high power terrestrial modules (600mW) lie below 220 FIT at 25°C. Wear-out phenomena is observed only for very high current level without any reliability impact under 1.1A. For the 1060nm chip, step-stress tests were performed and a set of devices were aged during more than 2000 hours in different stress conditions. First results are in accordance with 980nm product with more than 100khours estimated MTTF. These reliability and performance features of 980-1060nm laser diodes will make high-power single-mode emitters the best choice for a number of telecommunication and industrial applications in the next few years.

  13. Development of highly-efficient laser diodes emitting at around 1060nm

    NASA Astrophysics Data System (ADS)

    Pietrzak, A.; Huelsewede, R.; Zorn, M.; Meusel, J.; Loyo-Maldonado, V.; Sebastian, J.

    2017-02-01

    An overview is presented on the recent progress in the development of high power laser bars and single emitters emitting at wavelengths around 1060 nm. The development is focused on high reliability, thermal stability and high efficiency of the laser devices.

  14. Efficient Coupling of 527 nm Laser Beam Power to a Long Scalelength Plasma

    SciTech Connect

    Moody, J D; Divol, L; Glenzer, S H; MacKinnon, A J; Froula, D H; Gregori, G; Kruer, W L; Meezan, N B; Suter, L J; Williams, E A; Bahr, R; Seka, W

    2005-08-24

    We experimentally demonstrate that application of laser smoothing schemes including smoothing by spectral dispersion (SSD) and polarization smoothing (PS) increases the intensity range for efficient coupling of frequency doubled (527 nm) laser light to a long scalelength plasma with n{sub e}/n{sub cr} = 0.14 and T{sub e} = 2 keV.

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

    NASA Astrophysics Data System (ADS)

    Tawfieq, Mahmoud; Jensen, Ole Bjarlin; Hansen, Anders Kragh; Sumpf, Bernd; Paschke, Katrin; Andersen, Peter E.

    2015-03-01

    We demonstrate a concept for visible laser sources based on sum-frequency generation of beam combined tapered diode lasers. In this specific case, a 1.7 W sum-frequency generated green laser at 509 nm is obtained, by frequency adding of 6.17 W from a 978 nm tapered diode laser with 8.06 W from a 1063 nm tapered diode laser, inside a periodically poled MgO doped lithium niobate crystal. This corresponds to an optical to optical conversion efficiency of 12.1%. As an example of potential applications, the generated nearly diffraction-limited green light is used for pumping a Ti:sapphire laser, thus demonstrating good beam quality and power stability. The maximum output powers achieved when pumping the Ti:sapphire laser are 226 mW (CW) and 185 mW (mode-locked) at 1.7 W green pump power. The optical spectrum emitted by the mode-locked Ti:sapphire laser shows a spectral width of about 54 nm (FWHM), indicating less than 20 fs pulse width.

  16. Successful treatment of cutaneous Kaposi's sarcoma by the 585-nm pulsed dye laser.

    PubMed

    Marchell, N; Alster, T S

    1997-10-01

    The clinical appearance of Kaposi's sarcoma (KS) can cause significant disfigurement and lead to functional impairment, particularly if the lesions ulcerate and become secondarily infected. We describe a patient with a KS plaque on the face that was successfully treated with 585-nm pulsed dye laser (PDL) therapy. No recurrence of the tumor was noted 12 months after the final laser treatment.

  17. Applications using a Picosecond 14.7 nm X-Ray Laser

    SciTech Connect

    Dunn, J; Smith, R F; Nilsen, J; Shlyaptsev, V N; Filevich, J; Rocca, J J; Marconi, M C

    2001-09-21

    We report recent application experiments on the LLNL COMET tabletop facility using the picosecond, 14.7 nm Ni-like Pd x-ray laser. This work includes measurements of a laser-produced plasma density profile with a diffraction grating interferometer.

  18. Successful Treatment of Becker's Nevus With Long-Pulsed 1064nm Nd:YAG and 755nm Alexandrite Laser and Review of the Literature.

    PubMed

    Wulkan, Adam J; McGraw, Timothy; Taylor, Mark

    2017-05-12

    Becker's Nevus is an aesthetically troublesome condition secondary to hyperpigmentation and hypertrichosis. Although several lasers have been employed with varying degrees of success, the exact devices and treatment parameters have yet to be elucidated. To assess the combination Nd:Yag and alexandrite laser as a safe and efficacious treatment for Becker's Nevus. In a 20-year-old Fitzpatrick Skin Type IV male, a Becker's Nevus was treated with six sessions of long-pulsed 1,064nm Nd:Yag laser at six-week intervals followed by five sessions of long-pulsed 755nm alexandrite laser at three-month intervals. This patient experienced a significant reduction in both hyperpigmentation and hypertrichosis after these treatment sessions. No serious adverse events were reported. This case supports the use of combination long-pulsed 1,064nm laser and 755nm laser as a safe and efficacious treatment for Becker's Nevus.

  19. Corneal thermal damage threshold dependence on the exposure duration for near-infrared laser radiation at 1319 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jiarui; Jiao, Luguang; Chen, Hongxia; Yang, Zaifu; Hu, Xiangjun

    2016-01-01

    The corneal damage effects induced by 1319-nm transitional near-infrared laser have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. The in vivo corneal damage thresholds (ED50s) were determined in New Zealand rabbits for 1319-nm laser radiation for exposure durations from 75 ms to 10 s. An additional corneal ED50 was determined at 1338 nm for a 5-ms exposure. The incident corneal irradiance diameter was fixed at 2 mm for all exposure conditions to avoid the influence of spot size on threshold. The ED50s given in terms of the corneal radiant exposure for exposure durations of 5 ms, 75 ms, 0.35 s, 2 s, and 10 s were 39.4, 51.5, 87.2, 156.3, and 311.1 J/cm2, respectively. The 39.4 J/cm2 was derived from the ED50 for 1338 nm (27.0 J/cm2). The ED50s for exposure durations of 75 ms to 10 s were correlated by a power law equation, ED50=128.9t0.36 in J/cm2, where t was the input in the unit of second, with correlation coefficient (R) of 0.997. Enough safe margins existed between the ED50s and the maximum permitted exposures from current laser safety standard.

  20. Treatment of tattoos with a 755-nm Q-switched alexandrite laser and novel 1064 nm and 532 nm Nd:YAG laser handpieces pumped by the alexandrite treatment beam.

    PubMed

    Bernstein, Eric F; Bhawalkar, Jay; Clifford, Joan; Hsia, James

    2010-11-01

    Multi-colored and even black tattoos often require more than one wavelength to remove the target pigment. The authors report here a novel alexandrite laser with two Nd:YAG laser handpieces pumped by the alexandrite treatment beam enabling the delivery of three wavelengths from a single device. To describe and evaluate the effectiveness of a novel Q-switched laser-pumped laser for treating tattoos. Twenty tattoos in 14 subjects were treated at four-week intervals using a combination of available wavelengths (532, 755 and 1064 nm) as determined by the treating physician. Digital cross-polarized photographs were taken before treatment and two months following the fourth and final treatment. Photographs were evaluated by three physician observers blinded as to the treatment condition and rated for clearance by the following scale: 1 = > 95 percent, 2 = 76-95 percent, 3 = 51-75 percent, 4 = 26-50 percent and 5 = 0-25 percent clearance. The average clearance score was 3.1, in the 51-75 percent range, two months following four treatments. No scarring, hyper- or hypopigmentation was noted on post-treatment photographs or by the treating physician. The alexandrite and alexandrite-pumped 532 nm and 1064 nm Q-switched lasers are effective for removing decorative tattoos, and represents the first commercial laser with laser-pumped, laser handpieces.

  1. 308-nm excimer laser ablation of human cartilage

    NASA Astrophysics Data System (ADS)

    Prodoehl, John A.; Rhodes, Anthony L.; Meller, Menachem M.; Sherk, Henry H.

    1993-07-01

    The XeCl excimer laser was investigated as an ablating tool for human fibrocartilage and hyaline cartilage. Quantitative measurements were made of tissue ablation rates as a function of fluence in meniscal fibrocartilage and articular hyaline cartilage. A force of 1.47 Newtons was applied to an 800 micrometers fiber with the laser delivering a range of fluences (40 to 190 mj/mm2) firing at a frequency of 5 Hz. To assess the effect of repetition rate on ablation rate, a set of measurements was made at a constant fluence of 60 mj/mm2, with the repetition rate varying from 10 to 40 Hz. Histologic and morphometric analysis was performed using light microscopy. The results of these studies revealed that the ablation rate was directly proportional to fluence over the range tested. Fibrocartilage was ablated at a rate 2.56 times faster than hyaline cartilage at the maximum fluence tested. Repetition rate had no effect on the penetration per pulse. Adjacent tissue damage was noted to be minimal (10 - 70 micrometers ).

  2. Photosensitivity of a diamond detector to laser radiation in the 220 - 355-nm region

    SciTech Connect

    Lipatov, E I; Panchenko, Aleksei N; Tarasenko, Viktor F; Shein, J; Krishnan, M

    2001-12-31

    The photosensitivity of detectors of laser radiation based on the natural type IIa diamond (Alameda Applied Sciences Corporation, USA) are studied at the wavelengths 222, 308, 337, and 353 nm. The limiting intensities (0.5 - 4 MW cm{sup -2}) of UV laser radiation are determined at which the detectors operate in a linear regime. (laser applications and other topics in quantum electronics)

  3. Promethium-doped phosphate glass laser at 933 and 1098 nm

    SciTech Connect

    Krupke, W.F.; Shinn, M.D.; Kirchoff, T.A.; Finch, C.B.; Boatner, L.A.

    1987-12-28

    A promethium (Pm/sup 3 +/) laser has been demonstrated for the first time. Trivalent promethium 147 doped into a lead-indium-phosphate glass etalon was used to produce room-temperature four-level laser emission at wavelengths of 933 and 1098 nm. Spectroscopic and kinetic measurements have shown that Pm/sup 3 +/ is similar to Nd/sup 3 +/ as a laser active ion.

  4. Behavior of 157 nm excimer-laser-induced refractive index changes in silica

    SciTech Connect

    Smith, Charlene M.; Borrelli, Nicholas F.

    2006-09-15

    This study describes the observation of large induced refractive index changes produced by 157 nm excimer laser exposure in high-purity synthetic silica glasses. With 157 nm exposure, large induced changes are observed within a few hundred thousand pulses of exposure. Similar to 193 nm exposures, exposure with polarized 157 nm light yields polarization-induced birefringence (PIB). However, the 157 nm exposure also exhibits a behavior not observed with 193 nm exposures; namely, the initial response of the glass is a decrease in refractive index, followed by an increase with continued exposure. An explanation of the behaviors for both wavelength results is proposed where the induced refractive index is considered to arise from two different concurrent phenomena. One produces a decreased refractive index and also accounts for the PIB. The other, which accounts for the increased refractive index, is associated with an isotropic laser-induced volume change.

  5. LASERS 808-nm laser diode bars based on epitaxially stacked double heterostructures

    NASA Astrophysics Data System (ADS)

    Davydova, Evgeniya I.; Konyaev, V. P.; Ladugin, M. A.; Lebedeva, E. I.; Marmalyuk, Aleksandr A.; Padalitsa, A. A.; Petrov, S. V.; Sapozhnikov, S. M.; Simakov, V. A.; Uspenskii, Mikhail B.; Yarotskaya, I. V.

    2010-10-01

    We have fabricated and investigated linear arrays of single laser diodes (LDs) and epitaxially stacked double LDs based on AlGaAs/GaAs heterostructures emitting in the 808-nm range. The power — current characteristic of the double-LD bars has a slope of 2.18 W A-1, which is almost twice that of the single-LD bars (1.16 W A-1). The voltage drop across the former bars is also larger. At a pump current of 60 A, the output power of 5-mm-long arrays of LDs based on epitaxially stacked double heterostructures is 100 W under quasi-cw pumping, which is a factor of 1.8 above that of the single-LD bars under identical conditions.

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

    PubMed Central

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

    2013-01-01

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

  7. Simultaneous dual-wavelength lasing at 1047 and 1053 nm and wavelength tuning to 1072 nm in a diode-pumped a-cut Nd : LiYF4 laser

    NASA Astrophysics Data System (ADS)

    Lin, Zhi; Wang, Yi; Xu, Bin; Cheng, Yongjie; Xu, Huiying; Cai, Zhiping

    2015-12-01

    We report on diode-end-pumped a-cut Nd:YLF laser on F→I transition. In a free-running regime, using an output coupler with a radius of curvature of 1000 mm, we obtain dual-wavelength laser operation at both π-polarized 1047 nm and σ-polarized 1053 nm with maximum output power of about 1.25 W and the highest slope efficiency of about 50.9% at pump power of 5.77 W at room temperature, for the first time to our knowledge. Furthermore, using a 0.1-mm glass plate as a wavelength selector, a dual-wavelength laser at 1047 and 1072 nm can also be yielded with the maximum output power of 0.34 W, which has not been reported before.

  8. Interaction between high power 532nm laser and prostatic tissue: in vitro evaluation for laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Peng, Yihlih Steven; Stinson, Douglas

    2011-03-01

    Photoselective vaporization of the prostate (PVP) has been developed for effective treatment of obstructive benign prostatic hyperplasia. To maximize tissue ablation for large prostate gland, identifying the optimal power level for PVP is still necessary. We investigated the effect of various power levels on in vitro bovine prostate ablation with a 532-nm laser system. A custom-made 532-nm laser was employed to provide various power levels, delivered through a newly designed 750-μm side-firing fiber. Tissue ablation efficiency was evaluated in terms of power (P; 120~200W), treatment speed of fiber (TS; 2~8 mm/s), and working distance between fiber and tissue surface (WD; 1~5 mm). Coagulation depth was also estimated macroscopically and histologically (H&E) at various Ps. Both 180 and 200W yielded comparable ablated volume (104.3+/-24.7 vs. 104.1+/-23.9 mm3 at TS=4 mm/s and WD=2 mm; p=0.99); thus, 180W was identified as the optimal power to maximize tissue ablation, by removing tissue up to 80% faster than 120W (41.7+/-9.9 vs. 23.2+/-3.4 mm3/s at TS=4 mm/s and WD=2 mm; p<0.005). Tissue ablation was maximized at TS=4 mm/s and ablated equally efficiently at up to 3 mm WD (104.5+/-16.7 mm3 for WD=1 mm vs. 93.4+/-7.4 mm3 for WD=3 mm at 180W; p=0.33). The mean thickness of coagulation zone for 180W was 20% thicker than that for 120W (1.31+/-0.17 vs. 1.09+/-0.16 mm; p<0.005). The current in vitro study demonstrated that 180W was the optimal power to maximize tissue ablation efficiency with enhanced coagulation characteristics.

  9. Effect of Fiberoptic Collimation Technique on 808 nm Wavelength Laser Stimulation of Cochlear Neurons.

    PubMed

    Wang, Jingxuan; Lu, Jianren; Tian, Lan

    2016-06-01

    The purpose of this study was to evaluate the effects of fiberoptic collimation technique on auditory neural stimulation in the cochlea with 808 nm wavelength lasers. Recently, the pulsed near-infrared lasers in the 800-1000 nm wavelength range have been investigated as an emerging technique to trigger auditory neural response in the cochlea. A laser beam divergence in the optical stimulation pathway exists, which may affect stimulation efficiency and spatial selectivity. The fiberoptic collimation technique was proposed for cochlear neuron stimulation, and the C-lens element was designed as the collimation structure. The spiral ganglion cells in deafened guinea pigs' cochlea were irradiated with collimated and uncollimated near-infrared lasers. Optically evoked auditory brainstem response (OABR) under the two laser output modes were recorded. Laser with the collimation technique evoked an average 58% higher OABR amplitude than the uncollimated laser output. In addition, the collimated laser setup consumed on average 35.2% of laser energy compared with the uncollimated laser when evoking the same OABR amplitude. The fiberoptic collimation technique improved stimulation efficiency and reduced stimulating energy consumption in near-infrared neural stimulation in cochlea. The positive effects of laser collimation technique could benefit further research in optically based cochlear implants.

  10. The Versatility of 980 nm Diode Laser in Dentistry: A Case Series

    PubMed Central

    Derikvand, Nahid; Chinipardaz, Zahra; Ghasemi, Sara; Chiniforush, Nasim

    2016-01-01

    Introduction: Laser surgery has been considered a popular alternative over conventional modalities in dentistry during the last few years. Among different types of lasers, diode lasers have gained special attention in oral soft tissue surgery. Case Reports: Five patients were referred to a private office. After careful evaluation of medical history and oral examination, oral diagnosis and treatment plan of each patient was established as follows: (1) A 21-year-old female with ankyloglossia (tongue-tie); (2) A 65-year-old female with a poor denture fit needing vestibuloplasty and frenectomy; (3) A 10-year-old male patient with pigmented gingiva in mandible and maxilla; (4) A 14-year-old female needing exposure of maxillary right canine for bracket bonding; and (5) A 25-year-old female patient who has a gingival maxillary frenum with a nodule. The treatment plan for all the patients was laser surgery with diode laser at 980 nm, in continuous mode. Results: All the patients experienced normal healing process with no postoperative complications. Favorable outcomes of laser surgery were observed on follow-up sessions. Conclusion: Considering the versatility of the 980 nm diode laser in oral soft tissue surgeries and the advantages of laser surgery, this study suggests the use of 980 nm diode laser in this regard. PMID:28144444

  11. The Versatility of 980 nm Diode Laser in Dentistry: A Case Series.

    PubMed

    Derikvand, Nahid; Chinipardaz, Zahra; Ghasemi, Sara; Chiniforush, Nasim

    2016-01-01

    Introduction: Laser surgery has been considered a popular alternative over conventional modalities in dentistry during the last few years. Among different types of lasers, diode lasers have gained special attention in oral soft tissue surgery. Case Reports: Five patients were referred to a private office. After careful evaluation of medical history and oral examination, oral diagnosis and treatment plan of each patient was established as follows: (1) A 21-year-old female with ankyloglossia (tongue-tie); (2) A 65-year-old female with a poor denture fit needing vestibuloplasty and frenectomy; (3) A 10-year-old male patient with pigmented gingiva in mandible and maxilla; (4) A 14-year-old female needing exposure of maxillary right canine for bracket bonding; and (5) A 25-year-old female patient who has a gingival maxillary frenum with a nodule. The treatment plan for all the patients was laser surgery with diode laser at 980 nm, in continuous mode. Results: All the patients experienced normal healing process with no postoperative complications. Favorable outcomes of laser surgery were observed on follow-up sessions. Conclusion: Considering the versatility of the 980 nm diode laser in oral soft tissue surgeries and the advantages of laser surgery, this study suggests the use of 980 nm diode laser in this regard.

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

    PubMed

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

    2017-08-01

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

  13. Single frequency 1083nm ytterbium doped fiber master oscillator power amplifier laser.

    PubMed

    Huang, Shenghong; Qin, Guanshi; Shirakawa, Akira; Musha, Mitsuru; Ueda, Ken-Ichi

    2005-09-05

    Single frequency 1083nm ytterbium fiber master oscillator power amplifier system was demonstrated. The oscillator was a linear fiber cavity with loop mirror filter and polarization controller. The loop mirror with unpumped ytterbium fiber as a narrow bandwidth filter discriminated and selected laser longitudinal modes efficiently. Spatial hole burning effect was restrained by adjusting polarization controller appropriately in the linear cavity. The amplifier was 5 m ytterbium doped fiber pumped by 976nm pigtail coupled laser diode. The linewidth of the single frequency laser was about 2 KHz. Output power up to 177 mW was produced under the launched pump power of 332 mW.

  14. Nd:GdVO4 slab laser with line-shaped end-pumping profile operating at 912 nm

    NASA Astrophysics Data System (ADS)

    Hong, H.; Liu, Q.; Liu, H.; Fu, X.; Gong, M.

    2011-05-01

    A continuous-wave laser with line-shaped end-pumping profile operating at 912 nm is presented. The maximum output power of 7.82 W is obtained, with a slop efficiency of 24.7% and beam quality factors of M {/x 2} ˜ 20, M {/y 2} ˜ 1.3. To the best of our knowledge, this is the first laser diode bar directly pumped Nd:GdVO4 slab laser based on the quasi-three-level 4 F 3/2 → 4 F 9/2 transition in neodymium. Furthermore, we disclose that the experimental setups can be improved by inserting a plano-concave cylindrical lens in the cavity to form a new quasi-concentric resonator to improve die mode-matching in x-direction.

  15. DFB Lasers Between 760 nm and 16 μm for Sensing Applications

    PubMed Central

    Zeller, Wolfgang; Naehle, Lars; Fuchs, Peter; Gerschuetz, Florian; Hildebrandt, Lars; Koeth, Johannes

    2010-01-01

    Recent years have shown the importance of tunable semiconductor lasers in optical sensing. We describe the status quo concerning DFB laser diodes between 760 nm and 3,000 nm as well as new developments aiming for up to 80 nm tuning range in this spectral region. Furthermore we report on QCL between 3 μm and 16 μm and present new developments. An overview of the most interesting applications using such devices is given at the end of this paper. PMID:22319259

  16. Compact 498-nm light source based on intracavity sum-frequency Nd:GGG laser

    NASA Astrophysics Data System (ADS)

    Wang, A. G.; Li, Y. L.

    2011-08-01

    We report a coherent cyan radiation at 498 nm by intracavity sum-frequency generation of the 937 and 1062 nm laser-lines of the Nd:GGG crystal. With a diode pump power of 18.2 W, the maximum cyan output power of 186 mW is obtained. The beam quality M2 value is 1.22 in the horizontal plane. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is first work on intracavity sum-frequency generation of a diode pumped Nd:GGG laser at 498 nm.

  17. Wavelength Dependence in the Analysis of Carbon Content in Coal by Nanosecond 266 nm and 1064 nm Laser Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Xiongwei; Wang, Zhe; Fu, Yangting; Li, Zheng; Ni, Weidou

    2015-08-01

    The wavelength dependence of laser induced breakdown spectroscopy (LIBS) in the analysis of the carbon contents of coal was studied using 266 nm and 1064 nm laser radiations. Compared with the 1064 nm wavelength laser ablation, the 266 nm wavelength laser ablation has less thermal effects, resulting in a better crater morphology on the coal pellets. Besides, the 266 nm wavelength laser ablation also provides better laser-sample coupling and less plasma shielding, resulting in a higher carbon line intensity and better signal reproducibility. The carbon contents in the bituminous coal samples have better linearity with the line intensities of atomic carbon measured by the 266 nm wavelength than those measured by the 1064 nm wavelength. The partial least square (PLS) model was established for the quantitative analysis of the carbon content in coal samples by LIBS. The results show that both of the 266 nm and 1064 nm wavelengths are capable of achieving good performance for the quantitative analysis of carbon content in coal using the PLS method. supported by National Natural Science Foundation of China (No. 51276100) and National Basic Research Program of China (973 Program) (No. 2013CB228501)

  18. Polysilyne resists for 193 nm excimer laser lithography

    NASA Astrophysics Data System (ADS)

    Kunz, Roderick R.; Bianconi, Patricia A.; Horn, Mark W.; Paladugu, R. R.; Shaver, David C.; Smith, David A. M.; Freed, Charles A.

    1991-06-01

    Polyalkylsilynes have been used as resists for 193-nm projection lithography. These resists can be either wet developed using toluene or dry developed using HBr reactive ion etching (RIE). Wet development relies on crosslinking via intermolecular Si-O-Si bond formation to reduce solubility (negative tone) whereas the dry development relies on photo-oxidation to induce etch selectivity (also negative tone). The sensitivity in either case ranges from 20 to 200 mJ/cm2 and depends on the resist formulation. The best resist compositions are those that contain predominantly small (n-butyl) aliphatic pendant groups rather than large (cyclohexyl, phenyl) pendant groups. Using a 0.33 NA catadioptric lens with a phase mask, equal line-and-space features as small as 0.15 micrometers have been printed and transferred through 1.0 micrometers of planarizing layer (aspect ratio > 6) using oxygen RIE.

  19. High efficiency single frequency 355 nm all-solid-state UV laser

    NASA Astrophysics Data System (ADS)

    Xie, Xiaobing; Wei, Daikang; Ma, Xiuhua; Li, Shiguang; Liu, Jiqiao; Zhu, Xiaolei; Chen, Weibiao

    2016-05-01

    A novel conductively cooled high energy single-frequency 355 nm all-solid-state UV laser is presented based on sum-frequency mixing technique. In this system, a pulsed seeder laser at 1064 nm wavelength, modulated by an AOM, is directly amplified by the cascaded multi-stage hybrid laser amplifiers, and two LBO crystals are used for the SHG and SFG, finally a maximum UV pulse energy of 226 mJ at 355 nm wavelength is achieved with frequency-tripled conversion efficiency as high as 55%, the pulse width is around 12.2 ns at the repetition frequency of 30 Hz. The beam quality factor M 2 of the output UV laser is measured to be 2.54 and 2.98 respectively in two orthogonal directions.

  20. Efficient laser systems for 935 and 942 nm for water vapor lidar

    NASA Astrophysics Data System (ADS)

    Eichler, Hans Joachim; Kallmeyer, Frank; Rhee, Hanjo; Riesbeck, Thomas; Strohmaier, Stephan

    2007-05-01

    Water vapour absorption wavelengths have been directly generated by diode pumped Nd:YGG crystals emitting at 935 nm and with Nd:GSAG crystals emitting at 942 nm in cw and pulsed operation. In addition the 1064 nm fundamental wavelength from Nd:YAG pump lasers with pulse lengths of 10 or 20 ns was shifted using Stimulated Raman Scattering (SRS) or Ti:Sapphire (TiSa) lasers. The potential of Nd:GSAG, Nd:YGG, SRS and TiSa laser systems is compared for future incorporation into a satellite based Lidar system. High output energies are possible by recent advances of fiber coupled diode sources allowing pulsed longitudinal pumping of Q-switched solid state lasers.

  1. Development and characterization of a 22 W narrow-linewidth 3186 nm ultraviolet laser

    NASA Astrophysics Data System (ADS)

    Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

    2016-10-01

    We demonstrate a high-power narrow-linewidth ultraviolet (UV) laser system at 318.6 nm for direct 6S1/2-nP (n = 70 to 100) Rydberg excitation of cesium atoms. Based on commercial fiber lasers and efficient nonlinear frequency conversion technology, 2.26 W of tunable UV laser power is obtained from cavity-enhanced second harmonic generation following sum-frequency generation of two infrared lasers at 1560.5 nm and 1076.9 nm to 637.2 nm. The maximum doubling efficiency is 57.3%. The typical UV laser power root-mean-square fluctuation is less than 0.87% over 30 minutes, and the continuously tunable range of the UV laser frequency is more than 6 GHz. Its beam quality factors M2 X and M2 Y are 1.16 and 1.48, respectively. This high-performance UV laser has significant potential use in quantum optics and cold atom physics.

  2. Light-induced self-written waveguide fabrication using 1550  nm laser light.

    PubMed

    Terasawa, Hidetaka; Tan, Freddy; Sugihara, Okihiro; Kawasaki, Akari; Inoue, Daisuke; Yamashita, Tatsuya; Kagami, Manabu; Maury, Olivier; Bretonnière, Yann; Andraud, Chantal

    2017-06-01

    Light-induced self-written (LISW) optical waveguides were fabricated for the first time, to the best of our knowledge, using a photopolymerizable resin system formed by 1550 nm pulse laser light. A two-photon absorption (TPA) chromophore with a TPA cross section of several hundred Goeppert-Mayer (GM) at 1550 nm was used. Furthermore, the optical interconnection between a single-mode fiber and a fiber Bragg grating was demonstrated by the present technique, using one-way irradiation of 1550 nm laser light through the single-mode fiber. The LISW waveguide formation using 1550 nm laser light offers a new and promising alternative route for optical interconnection in silicon photonics technology.

  3. Mode-locked Nd:YAG laser with output at 1052, 1061, 1064, and 1074 nm

    SciTech Connect

    Badalian, A.A.; Sapondzhian, S.O.; Sarkisian, D.G.; Torosian, G.A.

    1985-10-01

    The picosecond Nd:YAG laser with an output radiation at 1064 nm is currently widely used. However, in connection with many applications, picosecond pulses at other wavelengths are also needed. The present study is, therefore, concerned with the development of a picosecond laser which provides pulses at 1052, 1061.5, and 1073.7 nm. Lasing at 1052, 1061.5, 1064, and 1073.7 nm was achieved by varying the angle between the resonator axis and the normal to the etalon by four degrees. Attention is given to the measurement of the lengths of the ultrashort pulses, and the transverse distribution of the energy in the second harmonic for the wavelength 1052 nm. The discretely tunable picosecond Nd:YAG laser described appears to be a promising tool for many research applications. 9 references.

  4. In-band pumped polarized, narrow-linewidth Er:YAG laser at 1645 nm.

    PubMed

    Wang, Mingjian; Meng, Junqing; Hou, Xia; Chen, Weibiao

    2014-10-20

    We report a polarized, narrow-linewidth Er:YAG laser operating at 1645 nm, in-band pumped by a continuous-wave (CW), narrowband 1532 nm fiber-coupled laser diode (LD). A maximum polarized continuous wave output power of 8.45 W was obtained, resulting in an optical conversion efficiency of 56% with respect to the absorbed pump power. The central wavelength was measured to be 1645.45 nm, with a full width at half-maximum of 0.13 nm. For Q-switched operation, pulse energy of 12 mJ at 100 Hz pulse repetition frequency and 95 ns pulse duration was yielded. To the best of our knowledge, this polarized pulse energy is the highest energy reported for a Q-switched Er:YAG laser pumped by a CW LD.

  5. The experimental study of a CW 1080 nm multi-point pump fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xuexia; Ge, Tingwu; Ding, Xing; Tan, Qirui; Wang, Zhiyong

    2016-07-01

    In this paper, we report on a CW 1080 nm fiber laser cascaded-pumped by a CW 975 nm diode laser. The fiber used in the experiment has a core diameter of 20 μm (NA  =  0.06), inner clad of 400 μm (NA  =  0.46), and an absorption coefficient of about 1.26 dB m-1 at 975 nm. An output power of 780 W with an optical conversion efficiency of 71% has been achieved at a pump light of 1.1 kW. To the best of our knowledge, this is the first time that a 1080 nm CW fiber laser has used a cascaded-pump coupler.

  6. High-power 1018 nm ytterbium-doped fiber laser and its application in tandem pump.

    PubMed

    Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Huang, Liangjin; Xu, Jiangming; Zhou, Pu

    2015-09-20

    In this paper, we present our experimental results of a high-power 1018 nm fiber laser and its usage in tandem pump. A record output power of 476 W 1018 nm fiber laser is obtained with an efficiency of 78.2%. Utilizing a specially designed gain fiber, a one-stage high-power monolithic fiber amplifier tandem pumped by six 1018 nm fiber lasers is assembled. A 110 W 1090 nm seed is amplified to 2140 W, and the efficiency is as high as 86.9%. The beam quality factor M2 is measured to be 1.9. Limitations and possible solutions for purchasing higher output power are discussed.

  7. Influence of temperature on Nd:YAG/V:YAG compact laser generation at 1444 nm

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Novák, Jakub; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2010-02-01

    Compact Q-switched diode-pumped laser, emitting radiation at eye-safe wavelength 1444 nm, was studied. This laser was based on composite crystal (diameter 5mm) consisting of 4mm long Nd:YAG active medium diffusion bonded with 1mm long V:YAG saturable absorber (initial transmission @ 1444nm 94 %). The laser resonator mirrors were directly deposited onto the composite crystal surfaces. These mirrors were designed to ensure emission at 1444nm and to prevent parasitic lasing at other Nd3+ transmissions. The pump mirror (R < 10% for pump radiation @ 808 nm, R < 2% @ 1064 nm, R < 15% @ 1330 nm, HR @ 1444 nm) was placed on the Nd3+-doped YAG part. The output coupler with reflectivity 94% for the generated wavelength 1444nm was placed on the V3+-doped part (R < 5% @ 1064 nm, R < 15% @ 1330 nm). Temperature dependence of giant pulse energy and length was studied independently on pumping pulses duty cycle. It was found that for constant duty cycle 1% and for crystal holder temperature rise from 8.2 up to 43.2 °C the pulse width dropped from 31 to 5.1 ns and pulse energy rose from 17 to 57 μJ. This represents a pulse peak power increase from 0.54 up to 11kW. From a mathematical model of passively Q-switched laser it follows that this behaviour can be explained by temperature caused increase of ground-state absorption and ground-state to excited-state absorption ratio (FOM) of V:YAG saturable absorber at wavelength 1444nm in case if FOM ~ 1.

  8. Laser intervention on trabeculo-Descemet's membrane after resistant viscocanalostomy: Selective 532 nm gonioreconditioning or conventional 1064 nm neodymium-doped yttrium aluminum garnet laser goniopuncture?

    PubMed Central

    Sabur, Huri; Baykara, Mehmet; Can, Basak

    2016-01-01

    Purpose: To compare the results of conventional 1064 nm neodymium-doped yttrium-aluminum garnet laser goniopuncture (Nd:YAG-GP) and selective 532 nm Nd:YAG laser (selective laser trabeculoplasty [SLT]) gonioreconditioning (GR) on trabeculo-Descemet's membrane in eyes resistant to viscocanalostomy surgery. Methods: Thirty-eight eyes of 35 patients who underwent laser procedure after successful viscocanalostomy surgery were included in the study. When postoperative intraocular pressure (IOP) was above the individual target, the eyes were scheduled for laser procedure. Nineteen eyes underwent 532 nm SLT-GR (Group 1), and the remaining 19 eyes underwent conventional 1064 nm Nd:YAG-GP (Group 2). IOPs before and after laser (1 week, 1 month, 3 months, 6 months, 1 year, and last visit), follow-up periods, number of glaucoma medications, and complications were recorded for both groups. Results: Mean times from surgery to laser procedures were 17.3 ± 9.6 months in Group 1 and 13.0 ± 11.4 months in Group 2. Mean IOPs before laser procedures were 21.2 ± 1.7 mmHg in Group 1 and 22.8 ± 1.9 mmHg in Group 2 (P = 0.454). Postlaser IOP measurements of Group 1 were 12.1 ± 3.4 mmHg and 13.8 ± 1.7 mmHg in the 1st week and last visit, respectively; in Group 2, these measurements were 13.6 ± 3.7 mmHg and 14.9 ± 4.8 mmHg, respectively. There were statistically significant differences (P < 0.001) in IOP reduction at all visits in both groups; the results of the two groups were similar (P > 0.05). Mean follow-up was 16.6 ± 6.4 months after SLT-GR and 18.9 ± 11.2 months after Nd:YAG-GP. Conclusions: While conventional Nd:YAG-GP and SLT-GR, a novel procedure, are both effective choices in eyes resistant to viscocanalostomy, there are fewer complications with SLT-GR. SLT-GR can be an alternative to conventional Nd:YAG-GP. PMID:27688277

  9. 486nm blue laser operating at 500 kHz pulse repetition frequency

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Blanchard, Jon; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    Compact, high power blue light in the 470-490nm region is difficult to generate due to the lack of laser sources which are easily convertible (through parametric processes) to those wavelengths. By using a pulsed Tm-doped fiber laser as a pump source for a 2-stage second harmonic generation (SHG) scheme, we have generated ~2W of 486.5nm light at 500kHz pulse repetition frequency (PRF). To our knowledge, this is the highest PRF and output power achieved in the blue region based on a frequency converted, monolithic fiber laser. This pump laser is a pulsed Tm-doped fiber laser/amplifier which generates 12.8W of 1946nm power at 500kHz PRF with diffraction-limited output from a purely single-mode fiber. The output from this laser is converted to 973nm through second harmonic generation (SHG). The 973nm is then converted to 486.5nm via another SHG stage. This architecture operates with very low peak power, which can be challenging from a nonlinear conversion standpoint. However, the low peak power enables the use of a single-mode monolithic fiber amplifier without undergoing nonlinear effects in the fiber. This also eliminates the need for novel fiber designs, large-mode area fiber, or free-space coupling to rod-type amplifiers, improving reliability and robustness of the laser source. Higher power and conversion efficiency are possible through the addition of Tm-doped fiber amplification stages as well as optimization of the nonlinear conversion process and nonlinear materials. In this paper, we discuss the laser layout, results, and challenges with generating blue light using a low peak power approach.

  10. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    SciTech Connect

    Thiyagarajan, Magesh; Thompson, Shane

    2012-04-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then

  11. Observation of the ^1S0 -- ^3P0 clock transition at 578 nm in atomic Yb

    NASA Astrophysics Data System (ADS)

    Hong, Tao

    2005-05-01

    We report the first observation of the strongly forbidden 6s^2 ^1S0 -- 6s6p ^3P0 transition near 578 nm in atomic Yb, which is weakly† allowed in the odd isotopes (^171, 173Yb) through internal hyperfine coupling† of the nuclear spin.† This transition has been proposed as one of the† primary† candidates for future optical frequency standards using alkaline earth atoms [1]. In our experiment, a 578 nm laser beam strikes cold Yb atoms† held in a magneto-optical trap (MOT). When this light is tuned to resonance† with the clock transition, a decrease in the MOT fluorescence is detected† as atoms are pumped into the metastable ^3P0 state and escape† from the trap. By chopping the MOT and clock beams out of phase, we avoid line shifts and broadening due to near-resonant trap light. Nearby 578 nm iodine lines, observed by Doppler-free† saturated absorption, are used as a frequency reference. †We find the ^ 171Yb transition to be about 2.5 GHz below the first hyperfine component of the iodine line 1852. We will present our measurements of the clock transition frequency, including a determination of the relative shift between the ^171Yb and ^173Yb isotopes.[1]S. G.† Porsev, A. Derevianko, E. N. Fortson, Phys. Rev. A 69, 021403(R)† (2004); H. Katori, in Proc. 6th Symposium Frequency Standards and Metrology, edited by P. Gill (World Scienti.c, Singapore, 2002), pp. 323-330

  12. Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals—A Literature Overview

    PubMed Central

    Kuypers, Thorsten; Gutknecht, Norbert

    2016-01-01

    Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment. PMID:27462611

  13. Injection locking of a low cost high power laser diode at 461 nm

    SciTech Connect

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

    2016-05-15

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

  14. Injection locking of a low cost high power laser diode at 461 nm

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  15. A Picosecond 14.7 nm X-Ray Laser for Probing Matter Undergoing Rapid Changes

    SciTech Connect

    Dunn, J; Smith, R F; Nilsen, J; Nelson, A J; Van Buuren, T W; Moon, S J; Hunter, J R; Filevich, J; Rocca, J J; Marconi, M C; Shlyaptsev, V N

    2002-10-07

    With laser-driven tabletop x-ray lasers now operating in the efficient saturation regime, the source characteristics of high photon flux, high monochromaticity, picosecond pulse duration, and coherence are well-matched to many applications involving the probing of matter undergoing rapid changes. We give an overview of recent experiments at the Lawrence Livermore National Laboratory (LLNL) Compact Multipulse Terawatt (COMET) laser using the picosecond 14.7 nm x-ray laser as a compact, ultrafast probe for surface analysis and for interferometry of laser-produced plasmas. The plasma density measurements for known laser conditions allow us to reliably and precisely benchmark hydrodynamics codes. In the former case, the x-ray laser ejects photo-electrons, from the valence band or shallow core-levels of the material, and are measured in a time-of-flight analyzer. Therefore, the electronic structure can be studied directly to determine the physical properties of materials undergoing rapid phase changes.

  16. Injection locking of a low cost high power laser diode at 461 nm.

    PubMed

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

    2016-05-01

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

  17. 2 nm continuously tunable 488nm micro-integrated diode-laser-based SHG light source for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Braune, M.; Maiwald, M.; Sumpf, B.; Tränkle, G.

    2016-04-01

    Raman spectroscopy in the visible spectral range is of great interest due to resonant Raman effects. Nevertheless, fluorescence and ambient light can mask the weak Raman lines. Shifted excitation Raman difference spectroscopy is a demonstrated tool to overcome this drawback. To apply this method, a light source with two alternating wavelengths is necessary. The spectral distance between these two wavelengths has to be adapted to the width of the Raman signal. According to the sample under investigation the width of the Raman signal could be in the range of 3 cm-1 - 12 cm-1. In this work, a micro-integrated light source emitting at 488 nm with a continuous wavelength tuning range up to 2 nm (83 cm-1) is presented. The pump source, a DFB laser emitting at 976 nm, and a periodically poled lithium niobate (PPLN) ridge waveguide crystal is used for the second harmonic generation (SHG). Both components are mounted on a μ-Peltier-element for temperature control. Here, a common wavelength tuning of the pump wavelength and the acceptance bandwidth of the SHG crystal via temperature is achieved. With the results the light source is suitable for portable Raman and SERDS experiments with a flexible spectral distance between both excitation wavelengths for SERDS with respect to the sample under investigation.

  18. 633-nm single-mode laser diode module with PM fiber output

    NASA Astrophysics Data System (ADS)

    Blume, G.; Jedrzejczyk, D.; Pohl, J.; Feise, D.; Sahm, A.; Eppich, B.; Nölleke, C.; Leisching, P.; Paschke, K.

    2017-02-01

    Several holographic and interferometric applications would benefit significantly from a diode laser based coherent light source near 633 nm. For this purpose a laser diode based on an AlGaAs/AlGaInP structure for emission in the red spectral range was developed. The laser chip features a ridge waveguide and a DBR surface grating at the rear side with a peak reflectivity at 633 nm. The laser was mounted in a butterfly-style package for temperature stabilization. The beam emitted by the laser diode was shaped with two cylindrical micro-lenses and passed through a custom-built CdMnTebased micro-optical isolator. The beam behind the isolator was coupled into a polarization maintaining (PM) single-mode fiber using an aspherical lens. The optical output power of the fiber was about 1.7 mW at 100 mA.

  19. Laser trapping dynamics of 200 nm-polystyrene particles at a solution surface

    NASA Astrophysics Data System (ADS)

    Yuyama, Ken-ichi; Sugiyama, Teruki; Masuhara, Hiroshi

    2013-09-01

    We present laser trapping behaviors of 200 nm-polystyrene particles in D2O solution and at its surface using a focused continuous-wave laser beam of 1064 nm. Upon focusing the laser beam into the solution surface, the particles are gathered at the focal spot, and their assembly is expanded to the outside and becomes much larger than the focal volume. The resultant assembly is observed colored under halogen lamp illumination, which is due to a periodic structure like a colloidal crystal. This trapping behavior is much different compared to the laser irradiation into the inside of the solution where a particle-like assembly with a size similar to that of the focal volume is prepared. These findings provide us new insights to consider how radiation pressure of a focused laser beam acts on nanoparticles at a solution surface.

  20. A 340-nm-band ultraviolet laser diode composed of GaN well layers.

    PubMed

    Yamashita, Yoji; Kuwabara, Masakazu; Torii, Kousuke; Yoshida, Harumasa

    2013-02-11

    We have demonstrated the laser operation of a short-wavelength ultraviolet laser diode with multiple-quantum-wells composed of GaN well layers. The laser action has been achieved in 340-nm-band far from the wavelength corresponding to GaN band gap under the pulsed current mode at room temperature. The device has been realized on the Al(0.2)Ga(0.8)N underlying layer. The AlN mole fraction of the underlying layer is 0.1 lower than that of the underlying layer which was used for the previously reported 342 nm laser diode. These results provide a chance to the next step for a shorter-wavelength ultraviolet laser diode.

  1. Optimizing treatment parameters for the vascular malformations using 1064-nm Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Gong, Wei; Lin, He; Xie, Shusen

    2010-02-01

    Near infrared Nd:YAG pulsed laser treatment had been proved to be an efficient method to treat large-sized vascular malformations like leg telangiectasia for deep penetrating depth into skin and uniform light distribution in vessel. However, optimal clinical outcome was achieved by various laser irradiation parameters and the key factor governing the treatment efficacy was still unclear. A mathematical model in combination with Monte Carlo algorithm and finite difference method was developed to estimate the light distribution, temperature profile and thermal damage in epidermis, dermis and vessel during and after 1064 nm pulsed Nd:YAG laser irradiation. Simulation results showed that epidermal protection could be achieved during 1064 nm Nd:YAG pulsed laser irradiation in conjunction with cryogen spray cooling. However, optimal vessel closure and blood coagulation depend on a compromise between laser spot size and pulse duration.

  2. Diode-pumped Q-switched Nd:YLF laser at 1313 nm

    NASA Astrophysics Data System (ADS)

    Xu, Shan; Gao, Shufang; Zheng, Chunyan

    2016-06-01

    In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical-optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.

  3. Therapeutic modalities for localized psoriasis: 308-nm UVB excimer laser versus nontargeted phototherapy.

    PubMed

    Mudigonda, Tejaswi; Dabade, Tushar S; West, Cameron E; Feldman, Steven R

    2012-09-01

    UVB phototherapy is an effective treatment modality for psoriasis. For patients with localized plaque-type lesions, 308-nm excimer laser phototherapy offers rapidly delivered, targeted, high UVB doses, while sparing adjacent healthy skin. We aimed to compare the advantages and disadvantages of the 308-nm xenon chloride (XeCI) UVB excimer laser with nontargeted broadband UVB (BB-UVB), narrowband UVB (NB-UVB), and psoralen plus UVA (PUVA) phototherapies. A PubMed search for studies evaluating the efficacy and safety of the laser versus nontargeted phototherapeutic modalities was conducted. Three prospective nonrandomized studies compared NB-UVB with excimer laser phototherapy. No head-to-head studies were found for BB-UVB or PUVA compared to excimer laser. Both the 308-nm excimer laser and nontargeted phototherapies were found to effectively clear localized psoriasis. Although it is proposed that excimer laser exclusively treats diseased skin with better response rates, split-body trials revealed no differences. Long-term studies are necessary to compare the effects of high-dose excimer laser regimens with nontargeted phototherapies.

  4. Absolute frequency measurements for hyperfine structure determination of the R(26) 62-0 transition at 501.7 nm in molecular iodine

    NASA Astrophysics Data System (ADS)

    Goncharov, Andrei; Lopez, Olivier; Amy-Klein, Anne; Du Burck, Frédéric

    2007-10-01

    The absolute frequencies of the hyperfine components of the R(26) 62-0 transition in molecular iodine at 501.7 nm are measured for the first time with an optical clockwork based on a femtosecond laser frequency comb generator. The set-up is composed of an Ar+ laser locked to a hyperfine component of the R(26) 62-0 transition detected in a continuously pumped low-pressure cell (0.33 Pa). The detected resonances show a linewidth of 45 kHz (half-width at half-maximum). The uncertainty of the frequency measurement is estimated to be 250 Hz.

  5. Growth of laser initiated damage in fused silica at 1053 nm

    SciTech Connect

    Norton, M A; Donohue, E E; Hollingsworth, W G; Feit, M D; Rubenchik, A M; Hackel, R P

    2004-11-10

    The effective lifetime of a laser optic is limited by both laser-induced damage and the subsequent growth of laser initiated damage sites. We have measured the growth rate of laser-induced damage on polished fused silica surfaces in 10 torr of air at 1053 nm at 10 ns. The data shows exponential growth in the lateral size of the damage site with shot number above a threshold fluence. The size of the initial damage influences the threshold for growth. We will compare the growth rates for input and output surface damage. Possible reasons for the observed growth behavior are discussed.

  6. Effects of the 755-nm Alexandrite laser on fine dark facial hair: review of 90 cases.

    PubMed

    Uyar, Belkiz; Saklamaz, Ali

    2012-05-01

    Laser hair removal is a relatively effective method for thick hair. Despite the risk for induction of fine hair growth, application of laser for fine dark hair is sometimes inevitable. We investigate the effects of 755-nm Alexandrite laser on fine dark facial hair and evaluate the induction rates of fine hair growth and case satisfaction. In the present study, the thickening rate of hairs (33.33%) was found to be higher than the previously published rates. However, reduction of hair density can be obtained when the laser sessions are continued.

  7. Quasi-three-level room-temperature Nd:YAG ring laser with high single-frequency output power at 946 nm

    SciTech Connect

    Freitag, I.; Henking, R.; Tuennermann, A.; Welling, H.

    1995-12-01

    Efficient room-temperature operation of a diode-pumped Nd:YAG laser is demonstrated for the quasi-three-level transition at 946 nm. Continuous-wave output powers of more than 800 mW cw in single-frequency operation are generated by application of a composite-cavity nonplanar ring laser. High amplitude and frequency stability of the emitted radiation is observed. {copyright} {ital 1995 Optical Society of America.}

  8. High-power 1300-nm Fabry-Perot and DFB ridge-waveguide lasers

    NASA Astrophysics Data System (ADS)

    Garbuzov, Dmitri Z.; Maiorov, Mikhail A.; Menna, Raymond J.; Komissarov, Anatoly V.; Khalfin, V.; Kudryashov, Igor V.; Lunev, Alexander V.; DiMarco, Louis A.; Connolly, John C.

    2002-05-01

    In this paper we summarize the results on the development of high power 1300 nm ridge waveguide Fabry-Perot and distributed-feedback (DFB) lasers. Improved performance of MOCVD grown InGaAsP/InP laser structures and optimization of the ridge waveguide design allowed us to achieve more than 800 mW output power from 1300 nm single mode Fabry-Perot lasers. Despite the fact that the beam aspect ratio for ridge lasers (30 degree(s) x 12 degree(s)) is higher than that for buried devices, our modeling and experiments demonstrated that the fiber coupling efficiency of about 75-80% could be routinely achieved using a lensed fiber or a simple lens pair. Fiber power of higher than 600 mW was displayed. Utilizing similar epitaxial structures and device geometry, the 1300 nm DFB lasers with output power of 500 mW have been fabricated. Analysis of the laser spectral characteristics shows that the high power DFB lasers can be separated into several groups. The single frequency spectral behavior was exhibited by about 20% of all studied DFB lasers. For these lasers, side-mode suppression increases from 45 dB at low current up to 60 dB at maximum current. About 30% of DFB lasers, at all driving currents, demonstrate multi-frequency spectra consisting of 4-8 longitudinal modes with mode spacing larger than that for Fabry-Perot lasers of the same cavity length. Both single frequency and multi frequency DFB lasers exhibit weak wavelength-temperature dependence and very low relative intensity noise (RIN) values. Fabry-Perot and both types of DFB lasers can be used as pump sources for Raman amplifiers operating in the 1300 nm wavelength range where the use of EDFA is not feasible. In addition, the single-mode 1300 nm DFB lasers operating in the 500 mW power range are very attractive for new generation of the cable television transmission and local communication systems.

  9. Dosimetry for lasers and light in dermatology: Monte Carlo simulations of 577 nm-pulsed laser penetration into cutaneous vessels

    NASA Astrophysics Data System (ADS)

    Jacques, Steven L.; Keijzer, Marleen

    1991-06-01

    The role of skin optics in planning proper dosimetry for radiant energy delivered by lasers and conventional light sources is presented. The optical properties of the epidermis, dermis, and cutaneous blood are summarized. The ability of laser pulses at 577-nm wavelength to penetrate into and around a large blood vessel is studied using Monte Carlo simulations. The variation in laser penetration for variable beam diameters and variable vessel depths in presented. The distinction between TOTAL PULSE ENERGY versus PULSE ENERGY DENSITY is illustrated. The topic of this paper is especially pertinent to laser therapy for portwine stain lesions.

  10. High-power and highly efficient Tm3+-doped silica fiber lasers pumped with diode lasers operating at 1150 nm.

    PubMed

    Jackson, Stuart D; Bugge, Frank; Erbert, Götz

    2007-10-01

    An output power of 1.74 W at 2.03 microm was generated at a slope efficiency of 51% when a double-clad Tm(3+)-doped silica fiber laser was pumped with high-power 1150 nm diode lasers. Pump excited state absorption from the upper laser level populates higher energy levels allowing cross relaxation to repopulate the upper laser level at a quantum efficiency greater than unity and to limit losses relating to additional pump excited state absorption. The output power was scaled to 4.77 W when both ends of the fiber were pumped.

  11. Laser materials based on transition metal ions

    NASA Astrophysics Data System (ADS)

    Moncorgé, Richard

    2017-01-01

    The purpose of this presentation is to review the spectroscopic properties of the main laser materials based on transition metal ions which lead to noticeable laser performance at room temperature and, for very few cases, because of unique properties, when they are operated at cryogenic temperatures. The description also includes the materials which are currently being used as saturable absorbers for passive-Q-switching of a variety of other near- and mid-infrared solid state lasers. A substantial part of the article is devoted first to the description of the energy levels and of the absorption and emission transitions of the transition metal ions in various types of environments by using the well-known Tanabe-Sugano diagrams. It is shown in particular how these diagrams can be used along with other theoretical considerations to understand and describe the spectroscopic properties of ions sitting in crystal field environments of near-octahedral or near-tetrahedral symmetry. The second part is then dedicated to the description (positions and intensities) of the main absorption and emission features which characterize the different types of materials.

  12. Analysis of frequency noise properties of 729nm extended cavity diode laser with unbalanced Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Pham, Tuan M.; Čížek, Martin; Hucl, Václav; Lazar, Josef; Hrabina, Jan; Řeřucha, Šimon; Lešundák, Adam; Obšil, Petr; Filip, Radim; Slodička, Lukáš; Číp, Ondřej

    2016-12-01

    We report on the frequency noise investigation of a linewidth-suppressed Extended Cavity Diode Laser (ECDL), working at 729 nm. Since the ECDL is intended as an excitation laser for the forbidden transition in a trapped and laser cooled 40Ca+ ion, an Hz-level linewidth is required. We present the experimental design that comprises a two-stage linewidth narrowing and a facility for frequency and noise analysis. The linewidth is first narrowed with a phase lock loop of the ECDL onto a selected component of an optical frequency comb where the frequency noise was suppressed with a fast electronic servo-loop controller that drives the laser injection current with a high bandwidth. The second stage comprises locking the laser onto a selected mode of a high-finesse passive optical cavity. The frequency analysis used an unbalanced Mach-Zehnder interferometer with a fiber spool inserted in the reference arm in order to give a general insight into the signal properties by mixing two separated beams, one of them delayed by the spool, and processing it with a spectral analyzer. Such a frequency noise analysis reveals what are the most significant noises contributions to the laser linewidth, which is a crucial information in field of ion trapping and cooling. The presented experimental results show the effect of the linewidth narrowing with the first stage, where the linewidth of ECDL was narrowed down to a kHz level.

  13. 63W output tandem-pumped thulium-doped silica fiber laser at 1980 nm

    NASA Astrophysics Data System (ADS)

    Xing, Ying-bin; Bu, Fan; Wang, Yi-bo; Li, Hai-qing; Peng, Jing-gang; Yang, Lv-yun; Dai, Neng-li; Li, Jin-yan

    2016-11-01

    We have demonstrated a high power and high efficiency thulium-doped silica fiber laser using a cascade tandem pumping method. A 1915nm Tm-doped fiber laser was used as a pump source for another Tm-doped fiber laser with the output power of 63W at 1980nm, corresponding to the slope efficiency of 80%, which is the highest power to our best knowledge. And the 3dB bandwidth was 0.24nm. The 1915nm Tm-doped fiber laser was pumped by 793nm diode laser and the slope efficiency was 51%. The preform of double cladding Tm-doped fiber for the tandem pumped fiber laser was manufactured by MCVD with using the vapor-solution hybrid doping method. The fiber has a 25μm diameter, 0.098 NA(numerical aperture) core and 400μm diameter, 0.46 NA inner cladding. In the tandem pumped fiber laser, the resonant cavity consist of a high reflection FBG at 1980nm, flat fiber end and the homemade Tm-doped silica fiber. The optimal active fiber length was presented and it is found that when the length of homemade Tm-doped silica fiber was 7m, the efficiency was the highest. The influence of Tm concentration and ratio of Tm ion and Al ion on the efficiency was also explored. And it is found that the thulium-doped silica fiber with lower Tm concentration and higher Tm:Al ratio had lower optical efficiency. Meanwhile, the optimal fiber length became shorter.

  14. Enhancement of transepidermal skin clearing agent delivery using a 980 nm diode laser.

    PubMed

    Stumpp, O F; Welch, A J; Milner, T E; Neev, J

    2005-10-01

    Patient compliant optical skin clearing requires non-invasive topical delivery of clearing agents such as glycerol. This requires reducing the skin barrier function by disrupting stratum corneum integrity, which was achieved using a 980 nm diode laser with artificial absorption substrates on the skin surface. Reduction of light scattering has the potential to improve many current and novel diagnostic and therapeutic applications of lasers in medicine. In vivo hamster and rat skin was used to test optical skin clearing. Absorption substrates were applied to the skin after shaving. These included black ink, dark children's rub-on tattoo, and carbon paper. 980 nm cw laser light was used to ablate these substrates and to heat the skin surface to enhance the diffusion of topically applied glycerol for optical skin clearing. Increased light penetration was determined from amplitude optical coherence tomography data. Results indicate an improvement of the ability to measure an OCT signal at a wavelength of 1,290 nm up to 42% deeper into in vivo rodent skin using a 980 nm laser with a fluence of less than 0.96 J/mm(2) to alter the stratum corneum. The use of an inexpensive diode laser can significantly enhance the delivery of topically applied glycerol for optical skin clearing. The laser use involves application of an absorption substrate onto the skin surface. Using carbon paper left no unwanted residue behind and is considered optimal for this purpose.

  15. Nanosecond laser-induced damage of transparent conducting ITO film at 1064nm

    NASA Astrophysics Data System (ADS)

    Yoo, Jae-Hyuck; Adams, John J.; Menor, Marlon G.; Olson, Tammy Y.; Lee, Jonathan R. I.; Samanta, Amit; Bude, Jeff; Elhadj, Selim

    2016-12-01

    Transparent conducting films with superior laser damage performance have drawn intense interests toward optoelectronic applications under high energy density environment. In order to make optoelectronic applications with high laser damage performance, a fundamental understanding of damage mechanisms of conducting films is crucial. In this study, we performed laser damage experiments on tin-doped indium oxide films (ITO, Bandgap = 4.0 eV) using a nanosecond (ns) pulse laser (1064 nm) and investigated the underlying physical damage mechanisms. Single ns laser pulse irradiation on ITO films resulted in common thermal degradation features such as melting and evaporation although the laser photon energy (1.03 eV, 1064 nm) was smaller than the bandgap. Dominant laser energy absorption of the ITO film is attributed to free carriers due to degenerate doping. Upon multi-pulse irradiation on the film, damage initiation and growth were observed at lower laser influences, where no apparent damage was formed upon single pulse, suggesting a laser-induced incubation effect.

  16. Investigation of single lateral mode for 852nm diode lasers with ridge waveguide design

    NASA Astrophysics Data System (ADS)

    Liu, Chu; Guan, Baolu; Mi, Guoxin; Liao, Yiru; Liu, Zhenyang; Li, Jianjun; Xu, Chen

    2016-11-01

    852nm Narrow linewidth lasers can be widely used in the field of ultra-fine spectrum measurement, Cs atomic clock control, satellite and optical fiber communication and so on. Furthermore, the stability of the single lateral mode is a very important condition to guarantee the narrow linewidth lasers. Here we investigate experimentally the influence of the narrow ridge structure and asymmetrical waveguide design on the stability single lateral mode of an 852nm diode laser. According to the waveguide theoretical analysis, ridge mesa etch depth (Δη , related to the refractive index difference of parallel to the junction) and ridge mesa width (the narrower the more control force to low order mode) are the main elements for lateral modes. In this paper, we designed different structures to investigate and verify major factors for lateral mode by experiment, and to confirm our thought. Finally, the 5μm mesa ridge laser, 800nm etch depth, with groove structure obtains excellent steady single lateral mode output by 150mA operating current and 30°C temperature. The optical spectrum FWHM is 0.5nm and side mode suppression ratio is 27dBm with uncoated. The laser with 1mm cavity length showed the threshold current of 50mA, a lasing wavelength of λ = 852.6nm, slope efficiency of above 0.7mW/mA. We accomplished single lateral mode of ridge waveguide edge-emitting lasers which can also be used as a laser source in the ultra-narrow linewidth external cavity laser system.

  17. Comparative study of 1,064-nm laser-induced skin burn and thermal skin burn.

    PubMed

    Zhang, Yi-Ming; Ruan, Jing; Xiao, Rong; Zhang, Qiong; Huang, Yue-Sheng

    2013-01-01

    Infrared lasers are widely used in medicine, industry, and other fields. While science, medicine, and the society in general have benefited from the many practical uses of lasers, they also have inherent safety issues. Although several procedures have been put forward to protect the skin from non-specific laser-induced damage, individuals receiving laser therapy or researchers who use laser are still at risk for skin damage. This study aims to understand the interaction between laser and the skin, and to investigate the differences between the skin damage caused by 1,064-nm laser and common thermal burns. Skin lesions on Wistar rats were induced by a 1,064-nm CW laser at a maximum output of 40 W and by a copper brass bar attached to an HQ soldering iron. Histological sections of the lesions and the process of wound healing were evaluated. The widths of the epidermal necrosis and dermal denaturalization of each lesion were measured. To observe wound healing, the epithelial gap and wound gap were measured. Masson's trichrome and picrosirius red staining were also used to assess lesions and wound healing. The thermal damage induced by laser intensified significantly in both horizontal dimension and in vertical depth with increased duration of irradiation. Ten days after wounding, the dermal injuries induced by laser were more severe. Compared with the laser-induced skin damage, the skin burn induced by an HQ soldering iron did not show a similar development or increased in severity with the passage of time. The results of this study showed the pattern of skin damage induced by laser irradiation and a heated brass bar. This study also highlighted the difference between laser irradiation and thermal burn in terms of skin damage and wound healing, and offers insight for further treatment.

  18. Investigation of the bandwidth of multimode optical fibers used with 1550-nm LED and laser sources

    NASA Technical Reports Server (NTRS)

    White, Preston A., III

    1992-01-01

    Multimode optical fibers are not intended to be used with 1550-nm sources; however, it is desirable to utilize 1300/1550-nm wavelength division multiplexing (WDM) on some multimode fibers at Kennedy Space Center (KSC). No information from fiber vendors nor from the literature is available to support this use. Preliminary studies at KSC have suggested that these fibers might be usable at 1550-nm if the fibers possessed enough bandwidth when sourced by LEDs. Detailed bandwidth studies were made on 12 multimode fibers using 1300- and 1550-nm lasers and LEDs. The results showed that the modal bandwidth at 1550-nm was about 50 percent of the 1300-nm value and that the chromatic dispersion could be predicted by extrapolating the vendor's specifications for wavelengths outside the 1550-nm region. Utilizing these data, predictions of the fiber's optical bandwidth were accurately made. Problems with launch conditions and possible differential attenuation at connectors was noted at 1300-nm but was less significant at 1550-nm. It appears that the multimode fibers studied will offer adequate performance in the 1550-nm region for a number of current KSC needs. Studies of additional fibers are encouraged to gain more confidence and better understanding of the 1550-nm bandwidth of KSC's multimode optical fibers before committing to 1300/1550-nm WDM.

  19. Characterization of red-near infrared transition for wheat and chickpea using 3 nm bandwidth data

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Vijayan, D.; Prasad, T. S.

    2001-01-01

    Enhancement of space based capabilities to discriminate different crops and different varieties of a particular crop needs measurement of (i) the shift in red edge and (ii) the slope of the sudden rise of reflectance in 680 - 760 nm spectral region as a function of Days After Sowing (DAS). To develop the knowledge base for catering to the analysis of future space-based hyperspectral measurements, ground based measurements in 3 nm bandwidth in visible - near Infrared region together with corresponding Leaf Area Index (LAI) observations were taken over the Crop Growth Cycle (CGC) of Wheat and Chickpea. The red edge for wheat crop was at 679 nm for 25 DAS and reached the upper limit i.e., 693.7 nm at 84 DAS and thereafter shifted backward to 679 nm at 108 DAS. There was no change in red edge value of 684.9 nm during 40 to 49 DAS and of 687.8 nm during 55 to 71 DAS. The slope of Red to NIR transition for wheat varied from 0.457 to peak value of 0.784 during 25 to 71 DAS and thereafter decreased to 0.073 at 108 DAS. The peak of Red to Near Infrared (NIR) transition slope and Ratio Vegetation Index (RVI) occurred at the same time i.e., 71 DAS. However, the upper most value of red edge shift occurred at 84 DAS. Paper discusses the above aspects including role of mid point of Red to NIR transition, interrelationships among the Red-NIR transition Slope, Red Edge, LAI and RVI for wheat and chickpea.

  20. Treatment endpoints for resistant port wine stains with a 755 nm laser.

    PubMed

    Izikson, Leonid; Anderson, R Rox

    2009-03-01

    Laser therapy of port wine stains (PWS) resistant to pulsed dye laser is challenging and controversial. Based on the theory of selective photothermolysis, vessels in such lesions may be specifically targeted with the laser wavelength of 755 nm. There is much deeper penetration of the near-infrared light and it is difficult to visualize laser-induced changes within the deeper dermis. The recognition of an appropriate immediate endpoint response with this wavelength would be helpful. This is a clinical observations report. We present examples of an appropriate PWS tissue response endpoint based on our clinical observations in resistant PWS treated with a 755 nm laser at high fluences (40-100 J/cm(2)), 1.5-ms pulse duration, with dynamic cooling device (DCD) cooling. Mild-to-moderate PWS lightening was associated with the immediate endpoint of a transient gray color that gradually evolved into persistent deep purpura within several minutes. We also discuss the clinical endpoints that represent undertreatment and overtreatment of PWS. It is important to attain, and maintain, the correct endpoint when treating PWS with this deeply penetrating near-infrared laser at high fluences in order to (a) induce lesional lightening, and (b) avoid deep dermal burns that may produce scarring. Judicious use of the 755 nm laser can be beneficial for resistant PWS.

  1. Single-mode 140 nm swept light source realized by using SSG-DBR lasers

    NASA Astrophysics Data System (ADS)

    Fujiwara, N.; Yoshimura, R.; Kato, K.; Ishii, H.; Kano, F.; Kawaguchi, Y.; Kondo, Y.; Ohbayashi, K.; Oohashi, H.

    2008-02-01

    We demonstrate a single-mode and fast wavelength swept light source by using Superestrucuture grating distributed Bragg reflector (SSG-DBR) lasers for use in optical frequency-domain reflectometry optical coherence tomography. The SSG-DBR lasers provide single-mode operation resulting in high coherency. Response of the wavelength tuning is very fast; several nanoseconds, but there was an unintentional wavelength drift resulting from a thermal drift due to injecting tuning current. The dri1ft unfortunately requires long time to converge; more than a few milliseconds. For suppressing the wavelength drift, we introduced Thermal Drift Compensation mesa (TDC) parallel to the laser mesa with the spacing of 20 μm. By controlling TDC current to satisfy the total electric power injected into both the laser mesa and the TDC mesa, the thermal drift can be suppressed. In the present work, we fabricated 4 wavelength's kinds of SSG-DBR laser, which covers respective wavelength band; S-band (1496-1529 nm), C-band (1529-1564 nm), L --band (1564-1601 nm), and L +-band (1601-1639). We set the frequency channel of each laser with the spacing 6.25 GHz and 700 channels. The total frequency channel number is 2800 channels (700 ch × 4 lasers). We simultaneously operated the 4 lasers with a time interval of 500 ns/channel. A wavelength tuning range of more than 140 nm was achieved within 350 μs. The output power was controlled to be 10 mW for all channels. A single-mode, accurate, wide, and fast wavelength sweep was demonstrated with the SSG-DBR lasers having TDC mesa structure for the first time.

  2. The thermal effects of therapeutic lasers with 810 and 904 nm wavelengths on human skin.

    PubMed

    Joensen, Jon; Demmink, Jan Hendrik; Johnson, Mark I; Iversen, Vegard V; Lopes-Martins, Rodrigo Álvaro Brandão; Bjordal, Jan Magnus

    2011-03-01

    To investigate the effect of therapeutic infrared class 3B laser irradiation on skin temperature in healthy participants of differing skin color, age, and gender. Little is known about the potential thermal effects of Low Level Laser Therapy (LLLT) irradiation on human skin. Skin temperature was measured in 40 healthy volunteers with a thermographic camera at laser irradiated and control (non-irradiated) areas on the skin. Six irradiation doses (2-12 J) were delivered from a 200 mW, 810 nm laser and a 60 mW, 904 nm laser, respectively. Thermal effects of therapeutic LLLT using doses recommended in the World Association for Laser Therapy (WALT) guidelines were insignificant; below 1.5°C in light, medium, and dark skin. When higher irradiation doses were used, the 60 mW, 904 nm laser produced significantly (p < 0.01) higher temperatures in dark skin (5.7, SD ± 1.8°C at 12 J) than in light skin, although no participants requested termination of LLLT. However, irradiation with a 200 mW, 810 nm laser induced three to six times more heat in dark skin than in the other skin color groups. Eight of 13 participants with dark skin asked for LLLT to be stopped because of uncomfortable heating. The maximal increase in skin temperature was 22.3°C. The thermal effects of LLLT at doses recommended by WALT-guidelines for musculoskeletal and inflammatory conditions are negligible (<1.5°C) in light, medium, and dark skin. However, higher LLLT doses delivered with a strong 3B laser (200 mW) are capable of increasing skin temperature significantly and these photothermal effects may exceed the thermal pain threshold for humans with dark skin color.

  3. A compact dual-wavelength Nd:LuVO4 laser with adjustable power-ratio between 1064 nm and 1342 nm lines by controlling polarization dependent loss

    NASA Astrophysics Data System (ADS)

    Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Zhang, Ling; He, Chaojian; Lin, Xuechun

    2017-01-01

    We demonstrate a compact dual-wavelength operation of Nd:LuVO4 laser with a power-ratio adjustable between 1064 nm and 1342 nm lines in a compound cavity configuration. The output power at two wavelengths of the laser indicates that it depends not only on pumping-power and but also on the controllable polarization loss in the cavity. Also, the power-ratio, defined as ratio between the output power at 1064 nm and that at 1342 nm, can be adjusted from 0 to 8 or higher accurately by rotating a quarter-wave plate (QWP) in the cavity.

  4. The effect of bleaching gel and (940 nm and 980 nm) diode lasers photoactivation on intrapulpal temperature and teeth whitening efficiency.

    PubMed

    Al-Karadaghi, Tamara S; Al-Saedi, Asmaa A; Al-Maliky, Mohammed A; Mahmood, Ali S

    2016-12-01

    This in vitro study aimed to investigate the whitening efficacy of 940 nm and 980 nm diode laser photoactivation in tooth bleaching by analysing pulp chamber temperature, as well as the change in tooth colour. Root canals of thirty extracted human lower premolars were prepared. Laserwhite* 20 bleaching agent containing 38% of hydrogen peroxide was photoactivated with 7 W output power of 940 nm and 980 nm diode lasers for 120 s. Bleaching gel reduced 27-29% of the temperature from reaching the pulp chamber. For shade assessment, only the groups photoactivated using diode lasers showed statistically significant differences from control group P < 0.001. Within the studied parameters, both 940 nm and 980 nm diode lasers produced a safe pulp temperature increase. Diode laser photoactivation of bleaching gel resulted in more efficient teeth whitening. Photoactivation with 940 nm diode laser yielded the highest change in colour with only minor increase in pulp chamber temperature. © 2016 Australian Society of Endodontology Inc.

  5. Time-resolved hydrino continuum transitions with cutoffs at 22.8 nm and 10.1 nm

    NASA Astrophysics Data System (ADS)

    Mills, R. L.; Lu, Y.

    2011-09-01

    Spectra of low energy, high current pinch discharges in pure hydrogen, oxygen, nitrogen, and helium were recorded in the EUV region, and continuum radiation was only observed from hydrogen [www.blacklightpower.com/pdf/GEN3_Harvard.pdf; Int. J. Hydrogen Energy 35, 8446 (2010); Cent. Eur. J. Phys. 8, 318 (2010)]. The continuum radiation bands at 10.1 and 22.8 nm and going to longer wavelengths for theoretically predicted transitions of hydrogen to lower-energy, so called "hydrino" states, was observed first at blacklight power, Inc. (BLP) and reproduced at the Harvard center for astrophysics (CfA). Considering the low energy of 5.2 J per pulse, the observed radiation in the energy range of about 120 eV to 40 eV and reference experiments, no conventional explanation was found to be plausible, including electrode metal emission, Bremsstrahlung radiation, ion recombination, molecular or molecular ion band radiation, and instrument artifacts involving radicals and energetic ions reacting at the CCD and H2 re-radiation at the detector chamber. To further study these continuum bands assigned to hydrinos, time resolved spectra were performed that showed a unique delay of the continuum radiation of about 0.1 μs and a duration of < 2 μs following the high-voltage pulse consistent with the mechanism of recombination to form the optimal high-density atomic hydrogen in the pinch that permits the H-H interactions to cause the hydrino transitions and corresponding emission.

  6. High efficiency hydrocarbon-free resonance transition potassium laser

    NASA Astrophysics Data System (ADS)

    Zweiback, Jason; Hager, Gordon; Krupke, William F.

    2009-05-01

    We experimentally demonstrate a high efficiency potassium laser using a 0.15 nm bandwidth alexandrite laser as the pump source. The laser uses naturally occurring helium as the buffer gas. We achieve a 64% slope efficiency and a 57% optical to optical conversion. A pulsed laser model shows good agreement with the data.

  7. Transscleral contact retinal photocoagulation with an 810-nm semiconductor diode laser

    SciTech Connect

    Jennings, T.; Fuller, T.; Vukich, J.A.; Lam, T.T.; Joondeph, B.C.; Ticho, B.; Blair, N.P.; Edward, D.P. )

    1990-07-01

    Since the 810-nm wavelength has marked transmissibility through the sclera and absorption by melanin, it would be ideal for transscleral photocoagulation. We performed experiments to determine if consistent transscleral chorioretinal lesions could be produced in Dutch belted pigmented rabbits using the 810-nm laser, and if this modality caused less blood-retinal barrier disruption than retinal cryopexy of clinically equivalent treatment areas. The laser applications produced whitish to grayish-white retinal lesions when the surgeon, under direct visualization, used low powers and long durations (5 to 10 seconds), and controlled the treatment duration. Histopathologic evaluation of a lesion demonstrated an intact sclera overlying the chorioretinal lesion. Vitreous protein concentration, which was measured to assess blood-retinal barrier disruption, was significantly less in eyes treated with transscleral photocoagulation than in eyes treated with cryopexy of clinically equivalent treatment areas. We conclude that transscleral 810-nm laser treatment may be a viable clinical alternative to retinal cryopexy.

  8. Broadly tunable (440-670 nm) solid-state organic laser with disposable capsules

    NASA Astrophysics Data System (ADS)

    Mhibik, Oussama; Leang, Tatiana; Siove, Alain; Forget, Sébastien; Chénais, Sébastien

    2013-01-01

    An innovative concept of thin-film organic solid-state laser is proposed, with diffraction-limited output and a broad tuning range covering the visible spectrum under UV optical pumping. The laser beam is tunable over 230 nm, from 440 to 670 nm, with a 3 nm full width at half maximum typical spectral width. The structure consists of a compact fixed bulk optical cavity, a polymeric intracavity etalon for wavelength tuning, as well as five different disposable glass slides coated with a dye-doped polymer film, forming a very simple and low-cost gain medium. The use of interchangeable/disposable "gain capsules" is an alternative solution to photodegradation issues, since gain chips can be replaced without realignment of the cavity. The laser lifetime of a single chip in ambient conditions and without encapsulation was extrapolated to be around 107 pulses at a microjoule energy-per-pulse level.

  9. Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

    DOEpatents

    Krupke, William F.; Payne, Stephen A.; Marshall, Christopher D.

    2001-01-01

    The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

  10. High energy 523 nm ND:YLF pulsed slab laser with novel pump beam waveguide design

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Zhu, Xiaolei; Ma, Jian; Lu, Tingting; Ma, Xiuhua; Chen, Weibiao

    2015-11-01

    A laser diode pumped Nd:YLF master oscillator power amplifier (MOPA) green laser system with high pulse energy and high stable output is demonstrated. At a repetition rate of 50 Hz, 840 mJ pulse energy, 9.1 ns pulse width of 1047 nm infrared laser emitting is obtained from the MOPA system. The corresponding peak power is 93 MW. Extra-cavity frequency doubling with a LiB3O5 crystal, pulse energy of 520 mJ at 523 nm wavelength is achieved. The frequency conversion efficiency reaches up to 62%. The output pulse energy instability of the laser system is less than 0.6% for one hour.

  11. CO2-Laser Polishing for Reduction of 351-nm Surface Damage Initiation in Fused Silica

    SciTech Connect

    Brusasco, R M; Penetrante, B M; Butler, J A; Maricle, S M; Peterson, J E

    2001-11-01

    We have applied a carbon dioxide (CO{sub 2}) raster scanning laser polishing technique on two types of fused silica flat optics to determine the efficacy of CO{sub 2}-laser polishing as a method to increase the 351-nm laser damage resistance of optic surfaces. R-on-1 damage test results show that the fluence for any given 355-nm damage probability is 10-15 J/cm{sup 2} higher (at 3 ns pulse length, scaled) for the CO{sub 2}-laser polished samples. Poor quality and good quality surfaces respond to the treatment such that their surface damage resistance is brought to approximately the same level. Surface stress and the resultant effect on wavefront quality remain key technology issues that would need to be addressed for a robust deployment.

  12. High-power in-band pumped Er:YAG laser at 1617 nm.

    PubMed

    Kim, J W; Shen, D Y; Sahu, J K; Clarkson, W A

    2008-04-14

    High-power room-temperature operation of an Er:YAG laser at 1617 nm in-band pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm is reported. The Er:YAG laser yielded 31 W of continuous-wave output in a beam with M(2) approximately = 2.2 for 72 W of incident pump power. The threshold pump power was 4.1 W and the slope efficiency with respect to incident pump power was approximately 47%. The influence of erbium doping level and resonator design on laser performance is discussed, and the prospects for further increase in output power and improvement in lasing efficiency are considered.

  13. Controlling H atom production in the 193 nm laser photolysis of triethylarsenic

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Deshmukh, Subhash; Brum, Jeffrey L.; Koplitz, Brent

    1991-05-01

    We report on the production of atomic hydrogen subsequent to the 193 nm photolysis of triethylarsenic (TEAs) using an excimer laser. The H atoms are probed via two-photon (121.6+364.7 nm) ionization, and the resulting H atom Doppler profile at Lyman-α is presented. Photolysis power dependence studies demonstrate that substantial H atom formation occurs at relatively low laser powers. However, the H atom signal actually begins to diminish as the photolysis laser power is increased beyond ˜70 MW/cm2. Correlations with time-of-fight mass spectral data suggest that ion channels are being accessed. The possible mechanisms for TEAs excitation that lead to H atom formation/depletion are presented, and the implications of these observations on controlling carbon incorporation in the laser-enhanced growth of films of GaAs, AlGaAs, etc. are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  15. Dosimetric analysis for low-level laser therapy (LLLT) of the human inner ear at 593 nm and 633 nm

    NASA Astrophysics Data System (ADS)

    Beyer, Wolfgang; Baumgartner, Reinhold; Tauber, Stefan

    1998-12-01

    The administration of low-level-laserlight for irradiation of the inner ear could represented a new therapeutic model for complex diseases of the inner ear. However, successful therapy requires a well-defined light dosimetry based on a dosimetric analysis of the human cochlea that represents a complex anatomy. The light distribution inside the cochlear windings, produced by an irradiation of the tympanic membrane, was quantitatively measured ex vivo for HeNe laser wavelengths of 593 nm and 633 nm. To obtain the space irradiance within an intact cochlea a correction factor of about 6 has been determined by Monte Carlo calculations. It follows from 3 contributions, first the backscattering of light in the bony parts removed during the preparation procedure of the specimen, second the change of index of refraction from the bony parts to air and third some geometrical factors due to the angular distribution of the radiation. The transmission of light across the tympanic cavity and the promontory depends strongly on the wavelength. Due to the observed spatial intensity variations of a factor 10 and more inside the cochlear windings the optimum external light dose has to be chosen with regard to the tonotopy of the ear.

  16. Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

    SciTech Connect

    Tong, A.K.; Tan, O.T.; Boll, J.; Parrish, J.A.; Murphy, G.F.

    1987-06-01

    It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.

  17. The generation of a continuous-wave Nd:YVO4/LBO laser at 543 nm by direct in-band diode pumping at 888 nm

    NASA Astrophysics Data System (ADS)

    Fu, S. C.; Wang, X.; Chu, H.

    2013-02-01

    We report the generation of a green laser at 543 nm by intracavity frequency doubling of the continuous-wave (cw) laser operation of a 1086 nm Nd:YVO4 laser under 888 nm diode pumping into the emitting level 4F3/2. An LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature, is used for the laser second-harmonic generation. At an incident pump power of 17.8 W, as high as 4.53 W cw output power at 543 nm is achieved. The optical-to-optical conversion efficiency is up to 25.4%, and the fluctuation of the green output power is better than 2.3% in a 30 min period.

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

    PubMed

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

    2013-09-01

    To compare the use of the 810nm diode laser with conventional surgery in the management of soft tissue mucogingival problems associated with orthodontic treatment. Orthodontic patients requiring different soft tissue surgical procedures were randomly assigned to receive conventional surgery or soft tissue diode laser, (wavelength 810 nm). Parameters documented include the type of anaesthesia used, intra and post operative pain, bleeding, the use of scalpel and sutures. The chi-squared test was used to test for significance at 95% confidence level. Probability values (p-values) less than 0.05 were regarded as significant. Only 2(16.7%) of the procedures carried out with the soft tissue laser required infiltration anaesthesia compared to 10 (90.9%) with conventional surgery and this was significant (P<0.001). Post operative pain was significantly reduced in all cases treated with the diode laser (P<0.001). There was also a significant difference (P<0.05) in post operative bleeding in all cases treated with the diode laser. No sutures were used in all soft tissue cases managed with the diode laser and this was significant (P<0.001). There was no statistically significant difference in treatment time in the use of the laser compared with conventional surgery. Orthodontic patients treated with the diode laser required less infiltration anaesthesia, had reduced bleeding during and after surgery, rapid postoperative haemostasis, elimination of the need for sutures and an improved postoperative comfort and healing.

  19. Tunable external-cavity diode laser at 650 nm based on a transmission diffraction grating.

    PubMed

    Laurila, Toni; Joutsenoja, Timo; Hernberg, Rolf; Kuittinen, Markku

    2002-09-20

    A tunable external-cavity diode laser (ECDL) based on a transmission diffraction grating in a Littrow mount has been developed and characterized. A single-transverse-mode diode laser at 650 nm is used in an external-cavity configuration in which the transmission grating is used as a dispersive element to select the single longitudinal mode. The transmission diffraction grating is made with electron-beam lithography. A tunable true single-mode cw output power of >20 mW is obtained from the ECDL. The total wavelength tuning range is 12 nm, and the mode-hop-free continuous tunability is >20 GHz.

  20. Multi-watts narrow-linewidth all fiber Yb-doped laser operating at 1179 nm.

    PubMed

    Kalita, Mridu P; Alam, Shaif-Ul; Codemard, Christophe; Yoo, Seongwoo; Boyland, Alexander J; Ibsen, Morten; Sahu, Jayanta K

    2010-03-15

    An all-fiber, narrow-linewidth, high power Yb-doped silica fiber laser at 1179 nm has been demonstrated. More than 12 W output power has been obtained, corresponding to a slope efficiency of 43% with respect to launched pump power, by core-pumping at 1090 nm. In order to increase the pump absorption, the Yb-doped fiber was heated up to 125 degrees C. At the maximum output power, the suppression of amplified spontaneous emission was more than 50 dB. Furthermore, theoretical work confirms that the proposed laser architecture can be easily scaled to higher power.

  1. Modeling of filamentation damage induced in silica by 351-nm laser pulses

    SciTech Connect

    Milam, D.; Manes, K.R.; Williams, W.H.

    1996-10-17

    A major risk factor that must be considered in design of the National Ignition Facility is the possibility for catastrophic self-focusing of the 351-nm beam in the silica optical components that are in the final section of the laser. Proposed designs for the laser are analyzed by the beam-propagation code PROP92. A 351-nm self-focusing experiment, induction of tracking damage, was done to provide data for validation of this code. The measured self-focusing lengths were correctly predicted by the code.

  2. Use of diode laser energy (808 nm) for selective photothermolysis of contaminated wounds

    NASA Astrophysics Data System (ADS)

    Bartels, Kenneth E.; Morton, Rebecca J.; Dickey, D. Thomas; Stair, Ernest L.; Payne, Marie E.; Schafer, Steven A.; Nordquist, Robert E.

    1995-05-01

    The objective of this study was to compare the antibacterial effects of selective laser treatments on contaminated wounds. Comparisons were made using the diode (808 nm) laser with and without an accompanying chromophore, Nd:YAG (1064 nm), and KTP (532 nm) lasers. A known quantity (mean concentration of 7.9 +/- 1.9 CFU/ml X 108) of bacterial organisms (Staphylococcus intermedius) was inoculated into skin incisions aseptically made on the backs of experimental rabbits. The bacteria were allowed to adhere/colonize for one hour, and each site was then treated with various laser modalities. Tissue samples were taken at one and forty-eight hours after treatment. The number of viable bacteria was then quantitated (CFU/ml) by a spot-plate counting technique. Initial results illustrated the fact that selective photothermolysis of superficial cellular layers of targeted tissue occurred with an accompanying decrease of bacterial numbers that virtually created a `clean' (organisms numbers less than 105 per gram of tissue) wound. This effect was especially noticeable using the diode laser (808 nm) and an accompanying chromophore, indocyanine green.

  3. 5kW GTWave fiber amplifier directly pumped by commercial 976nm laser diodes.

    PubMed

    Zhan, Huan; Liu, Qinyong; Wang, Yuying; Ke, Weiwei; Ni, Li; Wang, Xiaolong; Peng, Kun; Gao, Cong; Li, Yuwei; Lin, Honghuan; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2016-11-28

    With home-made fiber perform and special fiber drawing & coating technique, a new-type of (3 + 1) GTWave fiber theoretically designed for bi-directional pump method, was successfully fabricated and justified of integrating multi-kW pump energy from commercial 976nm laser diodes. This (3 + 1) GTWave fiber amplifier demonstrated uniform absorption of pump light and easy thermal management characteristics along the whole fiber length. This amplifier is capable of simultaneously aggregating 5.19kW pump power at 976nm and finally generating 5.07kW laser output at 1066.5nm with an optical-to-optical efficiency of 74.5%, the first publically-reported multi-kW GTWave fiber directly pumped with commercial 976nm laser diodes to the best of our knowledge. No power roll-over was found at 5kW level and further power scaling can be expected with more pump power. The results indicate that GTWave fiber is a competitive integrated fiber device to collect enough pump energy from low-cost commercial laser diodes for multi-kW fiber laser development.

  4. A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Forouhar, S.; Cody, J.; Lang, R. J.; Andrekson, P. A.

    1990-01-01

    The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.

  5. An Alternative Method of Evaluating 1540NM Exposure Laser Damage using an Optical Tissue Phantom

    DTIC Science & Technology

    2006-11-01

    size or duration parameters than this experiment. Pocock et a19 used the same parameters as this paper with hairless guinea pig ( Cavia porcellus ...exposure to infrared lasers. The phantom was exposed to a 1540-nm, Erbium:Glass, Q-switched laser with a beam diameter of 5 mm for 30 ns at varying power ...on the power density and is an indicator of dielectric breakdown when the amplitude reaches 2 X 105 V/cm. 13 Approved for Public Release; Distribution

  6. A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Forouhar, S.; Cody, J.; Lang, R. J.; Andrekson, P. A.

    1990-01-01

    The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.

  7. Generation of picosecond laser pulses at 1030 nm with gigahertz range continuously tunable repetition rate.

    PubMed

    Aubourg, Adrien; Lhermite, Jérôme; Hocquet, Steve; Cormier, Eric; Santarelli, Giorgio

    2015-12-01

    We report on a watt range laser system generating picosecond pulses using electro-optical modulation of a 1030 nm single frequency low noise laser diode. Its repetition rate is continuously tunable between 11 and 18 GHz. Over this range, output spectra and pulse characteristics are measured and compared with a numerical simulation. Finally, amplitude and residual phase noise measurements of the source are also presented.

  8. 1180 nm GaInNAs quantum well based high power DBR laser diodes

    NASA Astrophysics Data System (ADS)

    Viheriälä, Jukka; Aho, Antti T.; Virtanen, Heikki; Koskinen, Mervi; Dumitrescu, Michael; Guina, Mircea

    2017-02-01

    We report state-of-the-art results for 1180nm (narrow linewidth) laser diodes based on GaInNAs quantum wells and show results for ridge waveguide DBR laser diode including its reliability tests. Manuscript demonstrates 500 mW output power in continuous-wave operation at room temperature, wide single mode tuning region and narrow linewidth operation. Devices reached narrow linewidth operation (>250 kHz) across their operation band.

  9. 21-nm-range wavelength-tunable L-band Er-doped fiber linear-cavity laser

    NASA Astrophysics Data System (ADS)

    Yang, Shiquan; Zhao, Chunliu; Li, Zhaohui; Ding, Lei; Yuan, Shuzhong; Dong, Xiaoyi

    2001-10-01

    A novel method, which utilizes amplified spontaneous emission (ASE) as a secondary pump source, is presented for implanting a linear cavity erbium-doped fiber laser operating in L-Band. The output wavelength tuned from 1566 nm to 1587 nm, about 21 nm tuning range, was obtained in the experiment and the stability of the laser is very good.

  10. Tissue coloring with exogenous chromophores to extend surgical use of 808-nm diode lasers

    NASA Astrophysics Data System (ADS)

    Marangoni, Ovidio; Melato, Mauro

    2000-06-01

    Lasers with a wavelength between 351-1064nm, preset fluence and pulse duration induce a selective thermolysis of tissue chromophores. Specific exogenous chromophores, such as indocyanine green, are used in ophthalmology, in photodynamic therapy, in welding, and more recently for epilation. The aim of our study was to assess the effectiveness of a wavelength of 808nm on tissues stained with different exogenous chromophores whose absorption curves we studied by spectrophotometer. Out of five chromophores, methylene blue proved to be effective at 808nm. We tested the diode laser 808nm, at focused powers of 1, 2, 3, 5, 7 W in cw, for 1, 2, 3, 5, 7, 10 sec on skin specimens stained with 1 percent methylene blue in a small- spot sequence. At low powers the destructive effect was highly concentrated, both in depth and laterally, while greater intensities result in marked destruction even after a short irradiation time. The use of exogeneous chromophores increases absorption and reduces laser energy transmission and scatter. This study confirms that the selectivity of 808nm lasers can be 'tricked' since thermolysis is confined to the stained areas and there is less risk of damaging surrounding areas in the event of abrupt movements by either the surgeon or the patient, especially in the case of emotionally unstable or very young patients.

  11. 785nm dual-wavelength Y-branch DBR-RW diode laser with electrically adjustable wavelength distance between 0 nm and 2 nm

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2017-02-01

    Shifted excitation Raman difference spectroscopy is a powerful tool to separate the weak Raman lines from disturbing background light like fluorescence, day light or artificial light. When exciting the sample alternatingly with two slightly shifted wavelengths, the Raman lines follow the change whereas the background remains unchanged. Therefore, background free Raman spectra can be obtained measuring the two Raman spectra, subtracting the two signals and applying a reconstruction algorithm. When the spectral distance between the two wavelengths is the width of the Raman lines under study best signal-to-noise ratios can be achieved. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers with resistor heaters over the DBR gratings will be presented. The devices have a total length of 3 mm and a RW stripe width of 2.2 μm. The wavelengths are defined and stabilized using 500 μm long 10th order gratings with a designed spectral distance of 0.62 nm. Using the resistor heaters, this distance can be adjusted. The monolithic devices reach optical output powers up to 180 mW. Over the full range, they operate in single mode. The emission width is smaller than 13 pm (FWHM). At an output power of 50 mW the conversion efficiency is 0.22, which only slightly decreases down to 0.18 at maximal power. At an output power of 100 mW and with heater currents smaller than 600 mA, the spectral distance can be tuned from 0 nm up to 2 nm. The spectra remain single mode.

  12. The dynamics of femtosecond pulsed laser removal of 20 nm Ni films from an interface

    NASA Astrophysics Data System (ADS)

    Schrider, Keegan J.; Torralva, Ben; Yalisove, Steven M.

    2015-09-01

    The dynamics of femtosecond laser removal of 20 nm Ni films on glass substrates was studied using time-resolved pump-probe microscopy. 20 nm thin films exhibit removal at two distinct threshold fluences, removal of the top 7 nm of Ni above 0.14 J/cm2, and removal of the entire 20 nm film above 0.36 J/cm2. Previous work shows the top 7 nm is removed through liquid spallation, after irradiation the Ni melts and rapidly expands leading to tensile stress and cavitation within the Ni film. This work shows that above 0.36 J/cm2 the 20 nm film is removed in two distinct layers, 7 nm and 13 nm thick. The top 7 nm layer reaches a speed 500% faster than the bottom 13 nm layer at the same absorbed fluence, 500-2000 m/s and 300-700 m/s in the fluence ranges studied. Significantly different velocities for the top 7 nm layer and bottom 13 nm layer indicate removal from an interface occurs by a different physical mechanism. The method of measuring film displacement from the development of Newton's rings was refined so it could be shown that the 13 nm layer separates from the substrate within 70 ps and accelerates to its final velocity within several hundred picoseconds. We propose that removal of the bottom 13 nm is consistent with heterogeneous nucleation and growth of vapor at the Ni-glass interface, but that the rapid separation and acceleration of the 13 nm layer from the Ni-glass interface requires consideration of exotic phases of Ni after excitation.

  13. Long Coherence Length 193 nm Laser for High-Resolution Nano-Fabrication

    DTIC Science & Technology

    2008-06-27

    ns pulses, considering Kerr self phase modulation and perhaps Kramers- Kronig self phase modulation as well? What conversion efficiency to 193.4 nm is...Kramers- Kronig phase related to Actinix 31 6/27/2008 Long Coherence Length 193-nm Laser for High-Resolution Nano-Fabrication DARPA Phase I STTR Final...by. Usually the n 2 contribution is the larger of the two, and better characterized. I do not include a Kramers- Kronig contribution in the

  14. A compact, sub-Hertz linewidth 729 nm laser for a miniaturized 40Ca+ optical clock

    NASA Astrophysics Data System (ADS)

    Shang, Junjuan; Cao, Jian; Cui, Kaifeng; Wang, Shaomao; Zhang, Ping; Yuan, Jinbo; Chao, Sijia; Shu, Hualin; Huang, Xueren

    2017-01-01

    We present a compact, sub-Hertz 729 nm laser for a miniaturized 40Ca+ single-ion optical clock. An external cavity diode laser is frequency-stabilized to a horizontally mounted, vibration-insensitive and high-fineness ultra-low-expansion (ULE) cavity with Pound-Drever-Hall (PDH) method. The laser linewidth is measured to be about 0.9 Hz from a heterodyne beat note with the other 729 nm laser. After removing the linear drift of about 0.1 Hz/s, the fractional frequency instability is less than 2 × 10 - 15 (1 100 s). This compact, ultra-stable laser system with a volume about 0.1 m3 excluding the electronics has been employed into a miniaturized 40Ca+ single-ion optical clock. The clock frequency instability has been measured to be 3.4×10-14/τ1/2 (1 10,000 s) with a 729 nm laser probe pulse time of 20 ms.

  15. 510-nm pigmented lesion dye laser. Its characteristics and clinical uses.

    PubMed

    Grekin, R C; Shelton, R M; Geisse, J K; Frieden, I

    1993-04-01

    Benign pigmented lesions are of a cosmetic concern to many individuals. Numerous treatments exist, including several types of lasers. The Candela 510 nm pigmented lesion dye laser has recently been added to this armamentarium. It is designed specifically for the treatment of superficial pigmented lesions while significantly decreasing the risk of scarring and prolonged hypopigmentation. To describe the characteristics of the Candela pigmented lesion dye laser and report on the therapeutic outcome of patients treated for actinic lentigines, café-au-lait macules, melasma and red tattoos by one of the authors (RCG). The Candela 510 nm pigmented lesion dye laser was used to treat solar lentigines, café-au-lait macules, melasma and red tattoo. Excellent outcomes resulted on facial and hand lentigines (89% and 88% of patients had greater than 75% clearing, respectively), but often required more than one treatment. Lentigines located on the upper extremities and trunk improved less dramatically. Immediate greying occurred universally. Bruising was often noted. Treatment failures have been observed especially in treating lentigines located on the lower extremities. Café-au-lait macules responded inconsistently, with facial lesions giving the best results. Melasma responded poorly, often with hyperpigmentation. Three red tattoos cleared. Treatment failure may be related to inaccurate clinical assessment of pigment depth or regrowth of the lesion. Several cases are presented to demonstrate clinical and histologic effects of the laser. The Candela 510-nm pigmented lesion dye laser is an effective treatment for superficial pigmented lesions. Its associated morbidity is minimal.

  16. Successful removal of polyacrylamide hydrogel by pulsed fiberoptic 1444-nm Nd-YAG laser.

    PubMed

    Radmanesh, Mohammad; Radmanesh, Ramin; Bahadoram, Mohammad

    2013-12-01

    Tissue augmentation by polyacrylamide gel (PAAG) may lead to displacement or complications several years later and necessitate its removal. To use a fiberoptic 1444-nm neodymium-doped yttrium aluminum garnet (Nd-YAG) laser for removing polyacrylamide hydrogel augmentations. Five patients with frontal and cheek augmentations were referred for gel removal. After nerve block anesthesia, a 600-μm optical fiber tip with a metallic cannula was inserted into a hole created by a 16-gauge needle, and the laser was triggered. The cannula was moved in a fan pattern in the augmented area and was then removed. The tissue was squeezed from its outermost region toward the hole to extrude the gel. The laser system used was a 1444-nm fiberoptic Nd-YAG, obtained from Lutronic lasers, South Korea. The parameters used were: pulse rate = 30, pulse energy = 150 J, power = 4.5 W, and total energy = 400-1200 J. The heat of the laser tip liquefies the gel and by coagulating the surrounding tissues, it produces multiple patent canals. These two factors facilitate gel removal by squeezing the tissues. No temporary or permanent complication, such as hematoma, burning, or fibrosis, was detected. The 1444-nm Nd-YAG laser is a safe and efficient method for removing subcutaneous polyacrylamide hydrogel.

  17. Stretch marks: treatment using the 1,064-nm Nd:YAG laser.

    PubMed

    Goldman, Alberto; Rossato, Flávia; Prati, Clarissa

    2008-05-01

    Striae are frequent skin lesions that cause considerable aesthetic concern. The 1,064-nm long-pulsed Nd:YAG laser has been used to promote an increase in dermal collagen and is known to be a laser that has a high affinity for vascular chromophores. This study aims to verify the efficacy of the long-pulsed Nd:YAG laser in the treatment of immature striae. Twenty patients who had immature striae, i.e., red striae, were treated using the 1,064-nm long-pulsed Nd:YAG laser. The analysis of treatment efficacy was performed by the comparison between the images taken before and after each treatment session as well as through a subjective assessment carried out by the patients themselves. Results were considered satisfactory to both patients and doctors. A higher number of patients (55%) considered the results excellent when compared to the same assessment made by the doctor (40%). The clinical improvement of immature striae can be obtained with the use of the 1,064-nm long-pulsed Nd:YAG laser. The low incidence of side effects makes this laser a good alternative in the treatment of these common skin lesions.

  18. Incisional effects of 1940 nm thulium fiber laser on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Güney, Melike; Tunç, Burcu; Gülsoy, Murat

    2013-02-01

    Lasers of different wavelengths are being used in oral surgery for incision and excision purposes with minimal bleeding and pain. Among these wavelengths, those close to 2μ yield more desirable results on oral soft tissue due to their strong absorption by water. The emission of 1940 nm Thulium fiber laser is well absorbed by water which makes it a promising tool for oral soft tissue surgery. This study was conducted to investigate the potential of thulium fiber laser as an incisional and excisional oral surgical tool. Ovine tongue has been used as the target tissue due to its similarities to human oral tissues. Laser light obtained from a 1940 nm Thulium fiber laser was applied in contact mode onto ovine tongue completely submerged in saline solution in vitro, via a 600)μm fiber moved with a velocity of 0.5 mm /s to form incisions. There were a total of 9 groups determined by the power (2,5-3- 3,5 W), and number of passes (1-3-5). The samples were stained with HE for microscopic evaluation of depth of ablation and extent of coagulation. The depth of incisions produced with 1940 nm Thulium fiber laser increased with increasing power and number of passes, however an increase in the width of the coagulation zone was also observed.

  19. Follow-up survey of 308-nm laser treatment of psoriasis.

    PubMed

    Rodewald, Erin J; Housman, Tamara Salam; Mellen, Beverly G; Feldman, Steven R

    2002-01-01

    UVB treatment with a 308-nm excimer laser is a new treatment modality for localized psoriasis. The purpose of this study is to assess patients' impressions and satisfaction with 308-nm laser treatment of mild to moderate psoriasis. Telephone survey data were obtained from patients after participation in a case series study of 124 patients with mild to moderate psoriasis treated with 308-nm UVB laser treatment for a target plaque and other lesions. The survey included information on changes in the target plaque, remission time, changes in other areas of psoriasis, satisfaction with the result, side effects of treatment, and efficacy relative to other treatments. Patients (55% of total) reported overall satisfaction with the treatments, and 63% of patients thought they needed additional laser treatments, including for maintenance. Subjects (25%) reported that the laser treatments were better than any other treatment they had tried. Adverse effects were mild and had either disappeared or were significantly decreased in 86% of patients. Self reported length of remission compared favorably to those for other therapies for localized disease. UVB laser treatments provide a well-tolerated means to clear psoriasis plaques. The treatment provides a high level of patient satisfaction. Copyright 2002 Wiley-Liss, Inc.

  20. 1064 nm long-pulsed Nd:YAG laser treatment of basal cell carcinoma.

    PubMed

    Ortiz, Arisa E; Anderson, R Rox; Avram, Mathew M

    2015-02-01

    Standard surgical and destructive treatments for basal cell carcinoma (BCC) can result in significant morbidity and scarring, stimulating the investigation of alternative non-surgical options. The objective of this study was to determine the safety, clinical, and histological efficacy of pulsed, high-fluence 1064 nm Nd:YAG laser therapy for the treatment of BCC on the trunk and extremities. This was a prospective, non-randomized, open-label clinical trial. Ten subjects with a biopsy-proven BCC less than 1.5 cm in diameter on the trunk or extremities received one treatment with a 10 milliseconds pulsed 1064 nm Nd:YAG laser. Standard excision was performed 1 month after laser treatment to confirm histologic clearance. The laser treatment was quick and well tolerated. There was complete histologic clearance after one treatment in 92% of the BCC tumors, overall. At higher fluences, there was 100% histologic clearance after one treatment. No significant adverse events were seen, including scarring. The 1064 nm long-pulsed Nd:YAG laser may offer a safe alternative for treating BCC off the face. A larger study is highly warranted to confirm these preliminary results. Lasers Surg. Med. 47:106-110, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  1. Heading to 1 kW levels with laser bars of high-efficiency and emission wavelength around 880 nm and 940 nm

    NASA Astrophysics Data System (ADS)

    Pietrzak, A.; Woelz, M.; Huelsewede, R.; Zorn, M.; Hirsekorn, O.; Meusel, J.; Kindsvater, A.; Schröder, M.; Bluemel, V.; Sebastian, J.

    2015-03-01

    High-power quasi-CW laser bars are of great interest as pump sources of solid-state lasers generating high-energy ultrashort pulses for high energy projects. These applications require a continuous improvement of the laser diodes for reliable optical output powers and simultaneously high electrical-to-optical power efficiencies. An overview is presented of recent progress at JENOPTIK in the development of commercial quasi-CW laser bars emitting around 880 nm and 940 nm optimized for peak performance. At first, performances of 1.5 mm long laser bars with 75% fill-factor are presented. Both, 880 nm and 940 nm laser bars deliver reliable power of 500 W with wall-plug-efficiencies (WPE) <55% within narrow beam divergence angles of 11° and 45° in slow-axis and fast-axis directions, respectively. The reliability tests at 500 W powers under application quasi- CW conditions are ongoing. Moreover, laser bars emitting at 880 nm tested under 100 μs current pulse duration deliver 1 kW output power at 0.9 kA with only a small degradation of the slope efficiency. The applications of 940 nm laser bars require longer optical pulses and higher repetition rates (1-2 ms, ~10 Hz). In order to achieve output powers at the level of 1 kW under such long pulse duration, heating of the laser active region has to be minimized. Power-voltage-current characteristics of 4 mm long cavity bars with 50% fill-factor based on an optimized laser structure for strong carrier confinement and low resistivity were measured. We report an output power of 0.8 kW at 0.8 A with <60% conversion efficiency (52% WPE). By increasing the fill-factor of the bars a further improvement of the WPE at high currents is expected.

  2. Nanosecond laser-induced phase transitions in pulsed laser deposition-deposited GeTe films

    SciTech Connect

    Sun, Xinxing Thelander, Erik; Lorenz, Pierre; Gerlach, Jürgen W.; Decker, Ulrich; Rauschenbach, Bernd

    2014-10-07

    Phase transformations between amorphous and crystalline states induced by irradiation of pulsed laser deposition grown GeTe thin films with nanosecond laser pulses at 248 nm and pulse duration of 20 ns are studied. Structural and optical properties of the Ge-Te phase-change films were studied by X-ray diffraction and optical reflectivity measurements as a function of the number of laser pulses between 0 and 30 pulses and of the laser fluence up to 195 mJ/cm². A reversible phase transition by using pulse numbers ≥ 5 at a fluence above the threshold fluence between 11 and 14 mJ/cm² for crystallization and single pulses at a fluence between 162 and 182 mJ/cm² for amorphization could be proved. For laser fluences from 36 up to 130 mJ/cm², a high optical contrast of 14.7% between the amorphous and crystalline state is measured. A simple model is used that allows the discussion on the distribution of temperature in dependency on the laser fluence.

  3. Erbium: YAG laser (2,940 nm) treatment stimulates hair growth through upregulating Wnt 10b and β-catenin expression in C57BL/6 mice.

    PubMed

    Ke, Jin; Guan, Huiwen; Li, Shan; Xu, Li; Zhang, Li; Yan, Yuehua

    2015-01-01

    To evaluate the role of 2,940 nm erbium: YAG laser in hair growth in C57BL/6 mice. Anagen was experimentally induced by depilation. Healthy C57BL/6 mice (n=22) were randomly divided into four groups, with treatment of laser or minoxidil, or with combined laser and minoxidil treatments. The skin color of each mouse was observed each day. The time from telogen (pink skin color) to anagen (black coloration) phase and from anagen (black coloration) to catagen (all hairs grew out of the depilated skin) have been recorded. Hematoxylin and eosin (H&E) assay was done at fifteen days after the first treatment for each group to observe hair follicles and hair cycle score. Western blot analysis was utilized to detect the expression levels of Wnt 10-b and β-catenin. Black pigmentation started significantly earlier both in the laser and combination group than in the control group. Moreover, the time from anagen to catagen in the laser, minoxidil and combination groups were all significantly shorter from the control group. Histopathology with H&E staining showed an obvious increase in the number of hair follicles in the anagen phase caused by the treatment of 2,940 nm erbium: YAG laser and minoxidil. Similarly, the percentage of hair follicles in anagen VI accounted for 19.5%, 37.5%, 41.5% and 44% in control, laser, minoxidil, and combination group, respectively. Western blot analysis showed that both the levels of Wnt 10b and β-catenin were significantly increased by the treatment of 2,940 nm erbium: YAG laser. Our findings showed that 2,940-nm Er: YAG laser could promote hair growth by inducing hair cycle transition from telogen to anagen phases in C57BL/6 mice through up regulating Wnt 10b and β-catenin. These results suggest that 2,940-nm Er: YAG laser may be a potential therapy for hair loss.

  4. Laser-damage processes in cleaved and polished CaF{sub 2} at 248nm

    SciTech Connect

    Reichling, M.; Gogoll, S.; Stenzel, S.

    1996-12-31

    Single-shot irradiation of single crystal CaF{sub 2} with 248nm/14ns laser light results in various degrees of degradation and damage depending on the applied laser fluence. Phenomena range from subtle, non-topographic surface modification only detectable by secondary electrons of scanning electron microscopy (SE-SEM) over cracking along crystallographic directions to the ablation of crystalline material. Significant differences are found for cleaved and polished surfaces. Findings from SEM investigations, in-situ photoacoustic mirage measurements and visual inspection of irradiated samples form a comprehensive picture of the stages of laser-induced damage.

  5. Analysis of the optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm.

    PubMed

    Cho, C Y; Huang, T L; Cheng, H P; Huang, K F; Chen, Y F

    2016-01-11

    The optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm is theoretically and experimentally analyzed. It is clear that decreasing temperature can considerably eliminate the thermal population at the lower laser level to enhance the quantum efficiency. However, the narrowing of the absorption bandwidth for the gain medium leads to a reduction of the effective absorption efficiency as the temperature is decreased. Consequently, an optimal temperature for the maximum output power is found to be in the range of approximately 120 K to 140 K. It is experimentally verified that employing a pump source with a narrower emission spectrum linewidth contributes a more efficient output for the cryogenic laser.

  6. Mechanism of aneurysm formation after 830-nm diode-laser-assisted microarterial anastomosis

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Godlewski, Guilhem; Rouy, Simone

    1998-01-01

    A series of 830 nm diode laser assisted longitudinal aortorrhophy with a condition of 400 to 500 J/mm2 for one cm length of anastomosis versus conventional manual anastomoses were performed in 90 Wistar rats. With comparing with normal media process, a histologic examination of aneurysm formation was conducted. The results show that there are two important factors to cause aneurysm formation after laser assisted anastomosis: (1) vessel wall is damaged by laser heating; (2) proliferation of collagen fiber at adventitia is absent when media reconstruction.

  7. Simulations of a grazing-incidence pumped x-ray laser at 14.7 nm

    SciTech Connect

    Yan, F.; Zhang, J.; Dong, Q. L.; Lu, X.; Li, Y. J.

    2006-02-15

    Numerical simulations of the grazing-incidence pumped Ni-like Pd x-ray laser at 14.7 nm (4d{yields}4p, J=0{yields}1) is performed using a modified one-dimensional hydrodynamic code MEDUSA. The effective absorption of the main laser pulse in the gain region is greatly increased due to the lengthened propagation path. Results predict that a saturated output of the x-ray laser can be achieved with only subjoules driver energy on a 4-mm-long Pd target.

  8. High-power cw laser bars of the 750 - 790-nm wavelength range

    SciTech Connect

    Degtyareva, N S; Kondakov, S A; Mikayelyan, G T; Gorlachuk, P V; Ladugin, M A; Marmalyuk, Aleksandr A; Ryaboshtan, Yu L; Yarotskaya, I V

    2013-06-30

    We have developed the effective design of semiconductor heterostructures, which allow one to fabricate cw laser diodes emitting in the 750 - 790-nm spectral range. The optimal conditions for fabrication of GaAsP/AlGaInP/GaAs heterostructures by MOCVD have been determined. It is shown that the use of quantum wells with a precisely defined quantity mismatch reduces the threshold current density and increases the external differential efficiency. The results of studies of characteristics of diode laser bars fabricated from these heterostructures are presented. (lasers)

  9. Temperature-dependent 780-nm laser absorption by engineering grade aluminum, titanium, and steel alloy surfaces

    SciTech Connect

    Rubenchik, Alexander M.; Wu, Sheldon S. Q.; Kanz, V. Keith; LeBlanc, Mary M.; Lowdermilk, W. Howard; Rotter, Mark D.; Stanley, Joel R.

    2014-07-17

    When modeling laser interaction with metals for various applications it requires a knowledge of absorption coefficients for real, commercially available materials with engineering grade (unpolished, oxidized) surfaces. But, most currently available absorptivity data pertain to pure metals with polished surfaces or vacuum-deposited thin films in controlled atmospheres. A simple laboratory setup is developed for the direct calorimetric absorptivity measurements using a diode-array laser emitting at 780 nm. A scheme eliminating the effect of convective and radiative losses is implemented. Futhermore, the obtained absorptivity results differ considerably from existing data for polished pure metals and are essential for the development of predictive laser-material interaction models.

  10. 400 mW external cavity diode laser with narrowband emission at 445 nm.

    PubMed

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

    2014-07-01

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

  11. Biostimulative effects of 809 nm diode laser on cutaneous skin wounds

    NASA Astrophysics Data System (ADS)

    Solmaz, Hakan; Gülsoy, Murat; Ülgen, Yekta

    2015-03-01

    The use of low-level laser therapy (LLLT) for therapeutic purposes in medicine has become widespread recently. There are many studies in literature supporting the idea of therapeutic effects of laser irradiation on biological tissues. The aim of this study is to investigate the biostimulative effect of 809nm infrared laser irradiation on the healing process of cutaneous incisional skin wounds. 3-4 months old male Wistar Albino rats weighing 300 to 350 gr were used throughout this study. Lowlevel laser therapy was applied through local irradiation of 809nm infrared laser on open skin incisional wounds of 1 cm length. Each animal had six identical incisions on their right and left dorsal region symmetrical to each other. The wounds were separated into three groups of control, 1 J/cm2 and 3 J/cm2 of laser irradiation. Two of these six wounds were kept as control group and did not receive any laser application. Rest of the incisions was irradiated with continuous diode laser of 809nm in wavelength and 20mW power output. Two of them were subjected to laser irradiation of 1 J/cm2 and the other two were subjected to laser light with energy density of 3 J/cm2. Biostimulation effects of irradiation were studied by means of tensile strength tests and histological examinations. Wounded skin samples were morphologically examined and removed for mechanical and histological examinations at days 3, 5 and 7 following the laser applications. Three of the six fragments of skin incisions including a portion of peripheral healthy tissue from each animal were subjected to mechanical tests by means of a universal tensile test machine, whereas the other three samples were embedded in paraffin and stained with hematoxylin and eosin for histological examinations. The findings of the study show that tissue repair following laser irradiation of 809nm has been accelerated in terms of tissue morphology, strength and cellular content. These results seem to be consistent with the results of many

  12. Short-wavelength infrared laser activates the auditory neurons: comparing the effect of 980 vs. 810 nm wavelength.

    PubMed

    Tian, Lan; Wang, Jingxuan; Wei, Ying; Lu, Jianren; Xu, Anting; Xia, Ming

    2017-02-01

    Research on auditory neural triggering by optical stimulus has been developed as an emerging technique to elicit the auditory neural response, which may provide an alternative method to the cochlear implants. However, most previous studies have been focused on using longer-wavelength near-infrared (>1800 nm) laser. The effect comparison of different laser wavelengths in short-wavelength infrared (SWIR) range on the auditory neural stimulation has not been previously explored. In this study, the pulsed 980- and 810-nm SWIR lasers were applied as optical stimuli to irradiate the auditory neurons in the cochlea of five deafened guinea pigs and the neural response under the two laser wavelengths was compared by recording the evoked optical auditory brainstem responses (OABRs). In addition, the effect of radiant exposure, laser pulse width, and threshold with the two laser wavelengths was further investigated and compared. The one-way analysis of variance (ANOVA) was used to analyze those data. Results showed that the OABR amplitude with the 980-nm laser is higher than the amplitude with the 810-nm laser under the same radiant exposure from 10 to 102 mJ/cm(2). And the laser stimulation of 980 nm wavelength has lower threshold radiant exposure than the 810 nm wavelength at varied pulse duration in 20-500 μs range. Moreover, the 810-nm laser has a wider optimized pulse duration range than the 980-nm laser for the auditory neural stimulation.

  13. A flight-like absolute optical frequency reference based on iodine for laser systems at 1064 nm

    NASA Astrophysics Data System (ADS)

    Döringshoff, K.; Schuldt, T.; Kovalchuk, E. V.; Stühler, J.; Braxmaier, C.; Peters, A.

    2017-06-01

    We present an absolute optical frequency reference based on precision spectroscopy of hyperfine transitions in molecular iodine ^{127}I_2 for laser systems operating at 1064 nm. A quasi-monolithic spectroscopy setup was developed, integrated, and tested with respect to potential deployment in space missions that require frequency stable laser systems. We report on environmental tests of the setup and its frequency stability and reproducibility before and after each test. Furthermore, we report on the first measurements of the frequency stability of the iodine reference with an unsaturated absorption cell which will greatly simplify its application in space missions. Our frequency reference fulfills the requirements on the frequency stability for planned space missions such as LISA or NGGM.

  14. Long wavelength GaN blue laser (400-490nm) development

    SciTech Connect

    DenBaars, S P; Abare, A; Sink, K; Kozodoy, P; Hansen, M; Bowers, J; Mishra, U; Coldren, L; Meyer, G

    2000-10-26

    Room temperature (RT) pulsed operation of blue nitride based multi-quantum well (MQW) laser diodes grown on c-plane sapphire substrates was achieved. Atmospheric pressure MOCVD was used to grow the active region of the device which consisted of a 10 pair In{sub 0.21}Ga{sub 0.79}N (2.5nm)/In{sub 0.07}Ga{sub 0.93}N (5nm) InGaN MQW. The threshold current density was reduced by a factor of 2 from 10 kA/cm{sup 2} for laser diodes grown on sapphire substrates to 4.8 kA/cm{sub 2} for laser diodes grown on lateral epitaxial overgrowth (LEO) GaN on sapphire. Lasing wavelengths as long as 425nm were obtained. LEDs with emission wavelengths as long as 500nm were obtained by increasing the Indium content. These results show that a reduction in nonradiative recombination from a reduced dislocation density leads to a higher internal quantum efficiency. Further research on GaN based laser diodes is needed to extend the wavelength to 490nm which is required for numerous bio-detection applications. The GaN blue lasers will be used to stimulate fluorescence in special dye molecules when the dyes are attached to specific molecules or microorganisms. Fluorescein is one commonly used dye molecule for chemical and biological warfare agent detection, and its optimal excitation wavelength is 490 nm. InGaN alloys can be used to reach this wavelength.

  15. Fabrication of nanostructures on silicon carbide surface and microgroove sidewall using 800-nm femtosecond laser

    NASA Astrophysics Data System (ADS)

    Khuat, Vanthanh; Chen, Tao; Dao, Vanluu

    2015-07-01

    Nanoripples and nanoparticles have been fabricated on the surface of a silicon carbide sample with the irradiation of an 800-nm femtosecond laser in an underwater environment. When a linearly polarized laser was used, the nanoripples were perpendicular to the polarization direction of the incident laser, and the period of the nanoripples was dependent on the number of pulses. When a circularly polarized laser was used, nanoparticles with a diameter of approximately 80 nm were formed. In addition, we observed two kinds of nanoripples on the sidewall of the silicon carbide microgroove fabricated by femtosecond laser irradiation followed by chemical wet etching. When the polarization direction was aligned perpendicular to the writing direction, ripples parallel to the surface of the sample were formed. We attribute the formation of this kind of ripple to interference of the incident laser and the reflected wave. When the polarization direction was aligned parallel to the writing direction, the ripples are perpendicular to the surface of the sample. We attribute the formation of this kind of ripple to interference of incident laser and bulk electron plasma wave. A scanning electron microscope equipped with an energy dispersive X-ray spectroscope was employed to characterize the morphology of the structures.

  16. Comparison of the 308-nm excimer laser with the 308-nm excimer lamp in the treatment of vitiligo--a randomized bilateral comparison study.

    PubMed

    Shi, Qiong; Li, Kai; Fu, Jun; Wang, Yanchun; Ma, Cuiling; Li, Qiang; Li, Chunying; Gao, Tianwen

    2013-02-01

    Vitiligo is an acquired pigment disorder characterized by areas of depigmented skin resulting from the loss of epidermal melanocytes. Recently, several investigations have documented the benefits of excimer phototherapy (e.g., using the 308-nm excimer laser or the 308-nm excimer lamp) for the treatment of vitiligo. To compare the effectiveness of the 308-nm excimer laser with the 308-nm excimer lamp in the treatment of vitiligo patients. This intervention study was designed as a randomized self-control trial. Fourteen subjects with 48 symmetrical vitiligo lesions were enrolled in this study. One lesion was treated with the 308-nm excimer laser, and its counterpart was treated with the 308-nm excimer lamp. Lesions were treated three times a week with the same dose on both sides for a total of 20 sessions. All of the patients completed the study, and 48 lesions were treated. The two treatments exhibited similar results in terms of repigmentation. The 308-nm excimer lamp and the 308-nm excimer laser exhibited similar efficacies in treating vitiligo. © 2013 John Wiley & Sons A/S.

  17. Determination of transition probabilities for the 3p → 3s transition array in neon using laser induced breakdown spectroscopy

    SciTech Connect

    Asghar, Haroon; Ali, Raheel; Baig, M. Aslam

    2013-12-15

    We present here a study of the optical emission spectra of the laser produced neon plasma generated by a Nd:YAG laser at 1064 nm. The spectra were recorded using the laser induced breakdown spectroscopy 2000 detection system comprising of five spectrometers covering the entire visible region. The observed spectra yield all the optically allowed transitions between the 2p{sup 5}3p upper and 2p{sup 5}3s lower configurations based levels. The relative line strengths of all the dipole allowed transitions have been determined using the intensity ratios and compared with the J-file sum rule. The absolute transition probabilities have been calculated by using the lifetimes of the upper levels and the intensities of the observed spectral lines and show good agreement with the literature values.

  18. Therapeutic efficacy of long-pulsed 755-nm alexandrite laser for seborrheic keratoses.

    PubMed

    Kim, Y K; Kim, D-Y; Lee, S J; Chung, W S; Cho, S B

    2014-08-01

    Both ablative and non-ablative laser devices have been used for the cosmetic treatment of seborrheic keratoses. We analysed treatment outcomes and adverse events in the treatment of seborrheic keratoses using a long-pulsed 755-nm alexandrite laser without colour enhancement. A total of 216 seborrheic keratoses in 13 patients were treated with one or three sessions of long-pulsed 755-nm alexandrite laser at 1-month intervals. The lesions were treated with settings of 35 J/cm(2) using a 6-mm spot size, a 3-ms pulse width, and 1-2 passes or until the appearance of fine bubbles on the irradiated lesions. A total of 216 seborrheic keratoses were treated with a mean 1.1 ± 0.4 sessions of long-pulsed 755-nm alexandrite laser and achieved a mean objective improvement score of 3.4 ± 0.7. Morphologic factors significantly impacted the number of treatment sessions required; in particular, papular lesions seemed to require more repetitive long-pulsed 755-nm alexandrite laser treatments than macular lesions. However, objective improvement score was not affected by the type of the seborrheic keratoses. The colour of seborrheic keratoses did not significantly affect the objective improvement score or required treatment sessions. Most of the lesions became crusted within a few days after the laser treatment and spontaneously peeled off within 7 days. The delivery of long-pulsed, high fluence laser energy to seborrheic keratoses with protection of the epidermis by an integrated dynamic cooling device is an effective treatment with low risk of side-effects, even in light-coloured lesions with few target pigments. © 2013 European Academy of Dermatology and Venereology.

  19. 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)

  20. In-vitro fragmentation of biliary calculi with a 308-nm excimer laser

    NASA Astrophysics Data System (ADS)

    Shi, Wei-Qiang; Papaioannou, Thanassis; Vari, Sandor G.; Daykhovsky, Leon; Grundfest, Warren S.

    1990-06-01

    We report the use of a 308 mu XeC1 exciiuer laser for- biliary stone fragnientation. The 130 nsec laser pulses are delivered through tJV grade fused silica fibers to the target stones inmiersed in normal saline solution and placed in direct contact with the fiber. Sixty biliary calculi, 20 cholesterol and 40 pigment, were fragmented in vitro. The effect of laser repetition rate, energy fluence, and fiber core size on stone fragmentation was studied. Fragmentation thresholds for biliary calculi of different compositions were measured. It was found that higher fragmentation efficiency was obtained with larger fluence, lower repetition rate and fiber of larger core. Our study suggests that the long pulse 308 nm excimer laser may be an effective device for laser lithotripsy with low threshold and good efficiency for biliary stone fragmentation.

  1. 980-nm, 15-W cw laser diodes on F-mount-type heat sinks

    SciTech Connect

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

    2015-12-31

    We have studied the key optical emission parameters of laser diodes (emission wavelength, 980 nm; stripe contact width, 95 μm) mounted directly on F- and C-mount-type copper heat sinks, without intermediate elements (submounts). When effectively cooled by a thermoelectric microcooler, the lasers on the F-mount operated stably at output powers up to 20 W. The lasers were tested for reliable operation at an output power of 15 W for 100 h, and no decrease in output power was detected to within measurement accuracy. The experimentally determined maximum total efficiency is 71.7% and the efficiency at a nominal output power of 15 W is 61%. We compare parameters of the laser diodes mounted on C- and F-mounts and discuss the advantages of the F-mounts. (lasers)

  2. Short-term clinical outcomes of laser supported periodontal treatment concept using Er,Cr:YSGG (2780nm) and diode (940 nm): a pilot study

    NASA Astrophysics Data System (ADS)

    Odor, Alin A.; Violant, Deborah; Badea, Victoria; Gutknecht, Norbert

    2016-03-01

    Backgrounds: Er,Cr:YSGG (2780nm) and diode (940 nm) lasers can be used adjacent to the conventional periodontal treatment as minimally invasive non-surgical devices. Aim: To describe the short-term clinical outcomes by combining Er,Cr:YSGG (2780nm) and diode 940 nm lasers in non-surgical periodontal treatment. Materials and methods: A total of 10 patients with periodontal disease (mild, moderate, severe) - 233 teeth and 677 periodontal pockets ranging from 4 mm to 12 mm - were treated with Er,Cr:YSGG (2780nm) and diode (940 nm) lasers in adjunct to manual and piezoelectric scaling and root planning (SRP). Periodontal parameters such as mean probing depth (PD), mean clinical attachment level (CAL) and mean bleeding on probing (BOP) were evaluated at baseline and 6 months after the laser treatment using an electronic periodontal chart. Results: At baseline, the mean PD was 4.06 ± 1.06 mm, mean CAL was 4.56 ± 1.43 mm, and mean BOP was 43.8 ± 23.84 %. At 6 months after the laser supported periodontal treatments the mean PD was 2.6 ± 0.58 mm (p <0.001), mean CAL was 3.36 ± 1.24 mm (p <0.001) and mean BOP was 17 ± 9.34 % (p <0.001). Also 3 patients showed radiographic signs of bone regeneration. Conclusion: The combination of two laser wavelengths in adjunct to SRP offers significant improvements of periodontal clinical parameters such as PD, CAL and BOP. Keywords: Laser supported periodontal treatment concept, Er,Cr:YSGG and diode 940nm lasers, Scaling and root planning, Minimally invasive non-surgical device

  3. 589 nm sum-frequency generation laser for the LGS/AO of Subaru Telescope

    NASA Astrophysics Data System (ADS)

    Saito, Yoshihiko; Hayano, Yutaka; Saito, Norihito; Akagawa, Kazuyuki; Takazawa, Akira; Kato, Mayumi; Ito, Meguru; Colley, Stephen; Dinkins, Matthew; Eldred, Michael; Golota, Taras; Guyon, Olivier; Hattori, Masayuki; Oya, Shin; Watanabe, Makoto; Takami, Hideki; Iye, Masanori; Wada, Satoshi

    2006-06-01

    We developed a high power and high beam quality 589 nm coherent light source by sum-frequency generation in order to utilize it as a laser guide star at the Subaru telescope. The sum-frequency generation is a nonlinear frequency conversion in which two mode-locked Nd:YAG lasers oscillating at 1064 and 1319 nm mix in a nonlinear crystal to generate a wave at the sum frequency. We achieved the qualities required for the laser guide star. The power of laser is reached to 4.5 W mixing 15.65 W at 1064 nm and 4.99 W at 1319 nm when the wavelength is adjusted to 589.159 nm. The wavelength is controllable in accuracy of 0.1 pm from 589.060 and 589.170 nm. The stability of the power holds within 1.3% during seven hours operation. The transverse mode of the beam is the TEM 00 and M2 of the beam is smaller than 1.2. We achieved these qualities by the following technical sources; (1) simple construction of the oscillator for high beam quality, (2) synchronization of mode-locked pulses at 1064 and 1319 nm by the control of phase difference between two radio frequencies fed to acousto-optic mode lockers, (3) precise tunability of wavelength and spectral band width, and (4) proper selection of nonlinear optical crystal. We report in this paper how we built up each technical source and how we combined those.

  4. Investigating the ablation efficiency of a 1940-nm thulium fibre laser for intraoral surgery.

    PubMed

    Guney, M; Tunc, B; Gulsoy, M

    2014-08-01

    The use of a laser in surgical procedures involving the soft tissues is advantageous due to its sterile and hemostatic nature. Several different lasers are in use for intraoral soft tissue surgery; however, small, efficient, and fibre-coupled lasers are favoured due to the tightly confined nature of the intraoral environment. This study proposes the use of a 1940-nm thulium fibre laser (Tm:fibre laser) for intraoral soft tissue procedures. Its thermal effects when used to make incisions were investigated. This laser was chosen due to its output wavelength, which is absorbed well by water in biological tissues. Lamb tongues were used in the experiments. The laser was coupled to a 600-μm silica fibre and incisions were made in contact mode with a continuous wave. The extent of ablation and coagulation produced were measured at three different speeds, powers, and numbers of passes. The thermal effects of laser power, movement speed, and number of passes on incision depth and ablation efficiency were determined. The Tm:fibre laser is a promising tool for intraoral surgery, with excellent absorption by tissue, good coagulative qualities, and easy to manipulate fibre output. Its use as an incisional tool with very little to no carbonization is shown in this study.

  5. 1064-nm DFB laser diode modules applicable to seeder for pulse-on-demand fiber laser systems

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

    SciTech Connect

    Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.

    2014-04-28

    We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films.

  7. Spectroscopic and laser properties of SrMoO4:Tm3+ crystal under 1700-nm laser diode pumping

    NASA Astrophysics Data System (ADS)

    Doroshenko, M. E.; Papashvili, A. G.; Dunaeva, E. E.; Ivleva, L. I.; Osiko, V. V.; Jelinkova, H.; Sulc, J.; Nemec, M.

    2016-10-01

    Spectroscopic and laser properties of Tm3+ ions under 1700 nm excitation in SrMoO4 crystal are investigated. Negligible effect of cross-relaxation process (3H4sbnd 3F4, 3H6sbnd 3F4) on population of 3F4 level for thulium concentrations up to 0.25 at.% was demonstrated. Efficient lasing with slope efficiency up to 18% and broadband (over 100 nm) tuning at room temperature under 1700 nm diode pumping were obtained.

  8. Highly efficient picosecond diamond Raman laser at 1240 and 1485 nm.

    PubMed

    Warrier, Aravindan M; Lin, Jipeng; Pask, Helen M; Mildren, Richard P; Coutts, David W; Spence, David J

    2014-02-10

    We present a highly efficient picosecond diamond Raman laser synchronously-pumped by a 4.8 W mode-locked laser at 1064 nm. A ring cavity was adopted for efficient operation. With a low-Q cavity for first-Stokes 1240 nm, we have achieved 2.75 W output power at 1240 nm with 59% overall conversion efficiency. The slope efficiency tended towards 76% far above the SRS threshold, approaching the SRS quantum limit for diamond. A high-Q first-Stokes cavity was employed for second-Stokes 1485 nm generation through the combined processes of four-wave mixing and single-pass stimulated Raman scattering. Up to 1.0 W of second-stokes at 1485 nm was obtained, corresponding to 21% overall conversion efficiency. The minimum output pulse duration was compressed relative to the 15 ps pump, producing pulses as short as 9 ps for 1240 nm and 6 ps for 1485 nm respectively.

  9. [Retinal photocoagulation with a pulsed, frequency-doubled Nd:YAG laser (532 nm)].

    PubMed

    Roider, J; Schiller, M; el Hifnawi, E S; Birngruber, R

    1994-12-01

    The small difference in wavelength between an argon laser (514 nm) and a frequency-doubled Nd:YAG laser (532 nm), together with the advantage of the solid-state technology, makes the Nd:YAG laser likely to play a major role in retinal photocoagulation in the near future. For technical reasons all frequency-doubled Nd:YAG lasers work in a quasi-continuous mode, emitting a burst of highly repetitive short laser pulses during the exposure time desired. We investigated the side effects due to high peak irradiances of those short laser pulse trains (Crystal Focus Nd:YAG laser, Emerald; pulse duration 1-10 microseconds, repetition rate 13 KHz) in rabbits in comparison with a standard argon laser system (Zeiss, Visulas, Argon II). The energy necessary for blanching the retina was similar in both cases. As opposed to the argon laser system, subretinal bubbles were regularly visible ophthalmoscopically with the Nd:YAG system, when average powers as high as 200 mW were used. The ED50 power for bubble formation is about 2-3 times above the ED50 power for blanching. Thermal calculations show that this bubble formation effect is likely to be related to the peak power of the short pulses. The hemorrhage threshold is similar in both systems. However, light microscopically there is no difference between the two laser systems. Panretinal photocoagulation (300-500 microns, 100-200 ms) in patients with proliferative diabetic retinopathy produced such bubbles about once per 1000 lesions.

  10. Effects of 980-nm diode laser on the ultrastructure and fracture resistance of dentine.

    PubMed

    Faria, Maria Isabel Anastacio; Sousa-Neto, Manoel Damião; Souza-Gabriel, Aline Evangelista; Alfredo, Edson; Romeo, Umberto; Silva-Sousa, Yara Teresinha Correa

    2013-01-01

    Few reports have addressed the effects of diode laser irradiation at 980 nm on the morphology and fracture resistance of dentine. The purpose of this study is to evaluate the effects of 980-nm diode laser on the ultrastructure and fracture resistance of root dentine. The roots of 90 extracted canine teeth were divided into three groups according to the type of irrigating solution (water, NaOCl, and NaOCl/EDTA) and subdivided into three subgroups (n = 10) according to the amount of laser irradiation (without irradiation, 1.5 W/100 Hz and 3.0 W/100 Hz). The roots were filled with an epoxy resin-based sealer and gutta-percha and then subjected to a fracture resistance test. Data were analyzed by ANOVA and the Tukey test (p < 0.05). Additionally, 18 canine teeth were prepared using the same irrigation/irradiation protocols and evaluated by scanning electron microscopy (SEM). The SEM showed greater changes when the laser power increased, and the changes also varied according to the irrigating solution. A modified smear layer was observed in specimens that were treated with water and then laser-irradiated. The laser treatment did not alter the fracture resistance of roots treated with 1.5 W/100 Hz (246.3 ± 29.5 N) and 3.0 W/100 Hz (215.3 ± 25.1 N) laser power. The roots treated with NaOCl were more susceptible to fracture (199.4 ± 15.1 N) than those irrigated with water (254.2 ± 23.0 N) (p < 0.05). The 980-nm diode laser altered the morphology of the dentine but did not affect the fracture resistance of the roots.

  11. LD end-pumped acousto-optic Q-switched 1319 nm/1338 nm dual-wavelength Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Wu, C. T.; Yu, M.; Wang, C.; Yu, K.; Yu, Y. J.; Chen, X. Y.; Jin, G. Y.

    2016-10-01

    Laser characteristics of acousto-optic Q-switched operation of 1319 nm/1338 nm dual-wavelength composite Nd:YAG laser were studied. Maximum output power of 5.77 W was achieved in CW operation. Under Q-switched operation, the maximum peak power of 3.96 kW and minimum pulse width of 65.6 ns was obtained at repetition frequency of 20 kHz with the duty ratio of 96%. The influence of the duration of the ultrasonic field acted on the Q-switch to the output characteristics of dual-wavelength composite Nd:YAG laser had been reported first time.

  12. High-power 880-nm diode-directly-pumped passively mode-locked Nd:YVO₄ laser at 1342 nm with a semiconductor saturable absorber mirror.

    PubMed

    Li, Fang-Qin; Liu, Ke; Han, Lin; Zong, Nan; Bo, Yong; Zhang, Jing-Yuan; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

    2011-04-15

    A high-power 880-nm diode-directly-pumped passively mode-locked 1342 nm Nd:YVO₄ laser was demonstrated with a semiconductor saturable absorber mirror (SESAM). The laser mode radii in the laser crystal and on the SESAM were optimized carefully using the ABCD matrix formalism. An average output power of 2.3 W was obtained with a repetition rate of 76 MHz and a pulse width of 29.2 ps under an absorbed pump power of 12.1 W, corresponding to an optical-optical efficiency of 19.0% and a slope efficiency of 23.9%, respectively.

  13. Bismuth-doped telecommunication fibres for lasers and amplifiers in the 1400-1500-nm region

    SciTech Connect

    Dvoirin, V V; Mashinskii, V M; Medvedkov, O I; Dianov, Evgenii M; Umnikov, A A; Gur'yanov, Aleksei N

    2009-06-30

    Bismuth-doped optical fibres fully compatible with standard telecommunication fibres are developed. Lasers based on such fibres emitting in the spectral range 1430-1500 nm with an efficiency of up to 7.6% at room temperature and up to 10.5% at a temperature of -65{sup 0}C are fabricated. (waveguides. optical fibres)

  14. Fiber-based 1150-nm femtosecond laser source for the minimally invasive harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Huang, Jing-Yu; Guo, Lun-Zhang; Wang, Jing-Zun; Li, Tse-Chung; Lee, Hsin-Jung; Chiu, Po-Kai; Peng, Lung-Han; Liu, Tzu-Ming

    2017-03-01

    Harmonic generation microscopy (HGM) has become one unique tool of optical virtual biopsy for the diagnosis of cancer and the in vivo cytometry of leukocytes. Without labeling, HGM can reveal the submicron features of tissues and cells in vivo. For deep imaging depth and minimal invasiveness, people commonly adopt 1100- to 1300-nm femtosecond laser sources. However, those lasers are typically based on bulky oscillators whose performances are sensitive to environmental conditions. We demonstrate a fiber-based 1150-nm femtosecond laser source, with 6.5-nJ pulse energy, 86-fs pulse width, and 11.25-MHz pulse repetition rate. It was obtained by a bismuth borate or magnesium-doped periodically poled lithium niobate (MgO:PPLN) mediated frequency doubling of the 2300-nm solitons, generated from an excitation of 1550-nm femtosecond pulses on a large mode area photonic crystal fiber. Combined with a home-built laser scanned microscope and a tailor-made frame grabber, we achieve a pulse-per-pixel HGM imaging in vivo at a 30-Hz frame rate. This integrated solution has the potential to be developed as a stable HGM system for routine clinical use.

  15. Developments toward a reliable diode-pumped hydrocarbon-free 795-nm rubidium laser

    SciTech Connect

    Wu, S S; Soules, T F; Page, R H; Mitchell, S C; Kanz, V K; Beach, R J

    2008-05-07

    We report a 795-nm diode-pumpable Rb laser using a buffer gas of pure {sup 3}He. {sup 3}He gas enhances mixing of the Rb fine-structure levels. This enables efficient lasing at reduced He pressures and improved thermal management.

  16. Continuous-wave 193.4 nm laser with 120 mW output power.

    PubMed

    Sakuma, Jun; Kaneda, Yushi; Oka, Naoya; Ishida, Takayuki; Moriizumi, Koichi; Kusunose, Haruhiko; Furukawa, Yasunori

    2015-12-01

    This Letter describes an all-solid-state continuous-wave, deep-ultraviolet coherent source that generates more than 100 mW of output power at 193.4 nm. The source is based on nonlinear frequency conversion of three single-frequency infrared fiber laser master-oscillator power-amplifier (MOPA) light sources.

  17. Attenuation of 1310- and 1550-nm laser light through sound dental enamel

    NASA Astrophysics Data System (ADS)

    Jones, Robert S.; Fried, Daniel

    2002-06-01

    Inexpensive laser diodes and fiber-optic technology have revived optical transillumination as a promising diagnostic method for the early detection of dental caries. The principal factor limiting transillumination through dental hard tissue is light scattering in the normal enamel and dentin. Previous studies have shown that the scattering coefficient decreases with increasing wavelength. Therefore, the near-IR region is likely to be well suited for fiber optic transillumination. The objective of this study was to measure the optical attenuation of near-IR light through dental enamel at 1310-nm and 1550-nm. These laser wavelengths are readily available due to their suitability for application to fiber optic communication. In this study the collimated transmission of laser light through polished thin sections of dental enamel for various thickness from 0.1 to 2.5 mm was measured in cuvettes of index matching fluid with n= 1.63. Beer-Lambert plots show that the attenuation coefficients are 3.1+/- 0.17cm-1 and 3.8+/- 0.17cm-1 for 1310-nm and 1550-nm, respectively. This study indicates that near-IR laser wavelengths are well-suited for the transillumination of dental enamel for caries detection since the attenuation through normal tissue is an order of magnitude less than in the visible.

  18. Safety and efficacy of 2,790-nm laser resurfacing for chest photoaging.

    PubMed

    Grunebaum, Lisa D; Murdock, Jennifer; Cofnas, Paul; Kaufman, Joely

    2015-01-01

    Chest photodamage is a common cosmetic complaint. Laser treatment of the chest may be higher risk than other areas. The objective of this study was to assess the safety and efficacy of 2,790-nm chest resurfacing for photodamage. Twelve patients with Fitzpatrick skin types I-III were enrolled in this university IRB-approved study. Photo documentation was obtained at baseline and each visit. A test spot with the 2,790-nm resurfacing laser was performed on the chest. Patients who did not have adverse effects from the test spot went on to have a full chest resurfacing procedure. Patients were instructed on standardized aftercare, including sunscreen. A 5-point healing and photodamage improvement scale was used to rate improvement by both investigators and the patients and was obtained at 2 weeks, 1 month, 2 months, and 3 months. One pass chest treatment with the 2,790-nm resurfacing laser at fluences greater than or equal to 3.0 mJ with 10% overlap leads to unacceptable rates of hyperpigmentation. Double pass chest treatment at fluences less than or equal to 2.5 mJ with 10% overlap leads to mild improvement in chest photodamage parameters without significant or persistent adverse effects. Laser treatment of aging/photodamaged chest skin remains a challenge due to the delicacy of chest skin. Mild improvement may be obtained with double pass resurfacing with the 2,790-nm wavelength.

  19. In Vivo Photonic Stimulation of Sciatic Nerve with a 1470 nm Laser

    PubMed Central

    Dautrebande, Marie; Doguet, Pascal; Gorza, Simon-Pierre; Delbeke, Jean; Botquin, Yohan; Nonclercq, Antoine

    2016-01-01

    Photonic stimulation is a new modality of nerve stimulation, which could overcome some of the electrical stimulation limitations. In this paper, we present the results of photonic stimulation of rodent sciatic nerve with a 1470 nm laser. Muscle activation was observed with radiant exposure of 0.084 J/cm². PMID:27990230

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

    PubMed Central

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

    2013-01-01

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

  1. High-harmonic inverse-free-electron-laser interaction at 800 nm.

    PubMed

    Sears, Christopher M S; Colby, Eric R; Cowan, Benjamin M; Siemann, Robert H; Spencer, James E; Byer, Robert L; Plettner, Tomas

    2005-11-04

    We present the first direct observation of a higher-order inverse-free-electron-laser (IFEL) interaction. Interaction at the fourth, fifth, and sixth harmonics is observed from an IFEL operating at 800 nm. The harmonic spacing, relative harmonic strength, and transverse beam overlap of the interaction are all in good agreement with tracking simulations.

  2. High-Harmonic Inverse-Free-Electron-Laser Interaction at 800 nm

    NASA Astrophysics Data System (ADS)

    Sears, Christopher M. S.; Colby, Eric R.; Cowan, Benjamin M.; Siemann, Robert H.; Spencer, James E.; Byer, Robert L.; Plettner, Tomas

    2005-11-01

    We present the first direct observation of a higher-order inverse-free-electron-laser (IFEL) interaction. Interaction at the fourth, fifth, and sixth harmonics is observed from an IFEL operating at 800 nm. The harmonic spacing, relative harmonic strength, and transverse beam overlap of the interaction are all in good agreement with tracking simulations.

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

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Tuchin, Valery V.

    2009-02-01

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

  4. Fractional Erbium laser in the treatment of photoaging: randomized comparative, clinical and histopathological study of ablative (2940nm) vs. non-ablative (1540nm) methods after 3 months*

    PubMed Central

    Borges, Juliano; Cuzzi, Tullia; Mandarim-de-Lacerda, Carlos Alberto; Manela-Azulay, Mônica

    2014-01-01

    BACKGROUND Fractional non-ablative lasers keep the epidermis intact, while fractional ablative lasers remove it, making them theoretically more effective. OBJECTIVES To evaluate the clinical and histological alterations induced by fractional photothermolysis for treating photoaging, comparing the possible equivalence of multiple sessions of 1540nm Erbium, to one session of 2940nm Erbium. METHODS Eighteen patients (mean age 55.9) completed the treatment with three sessions of 1540nm fractional Erbium laser on one side of the face (50 mJ/mB, 15ms, 2 passes), and one session of 2940nm on the other side (5mJ/mB, 0.25ms, 2 passes). Biopsies were performed before and 3 months after treatment. Clinical, histological and morphometric evaluations were carried out. RESULTS All patients presented clinical improvement with no statistically significant difference (p> 0.05) between the treated sides. Histopathology revealed a new organization of collagen and elastic fibers, accompanied by edema, which was more evident with the 2940nm laser. This finding was confirmed by morphometry, which showed a decrease in collagen density for both treatments, with a statistical significance for the 2940nm laser (p > 0.001). CONCLUSIONS Three 1540nm sessions were clinically equivalent to one 2940nm session. The edema probably contributed to the positive results after three months, togheter with the new collagen and elastic fibers organization. The greater edema after the 2940nm session indicates that dermal remodeling takes longer than with 1540nm. It is possible that this histological superiority relates to a more prolonged effect, but a cohort longer than three months is needed to confirm that supposition. PMID:24770501

  5. Treatment of dilated pores with 1410-nm fractional erbium-doped fiber laser.

    PubMed

    Suh, Dong-Hye; Chang, Ka-Yeun; Lee, Sang-Jun; Song, Kye-Yong; Choi, Jeong Hwee; Shin, Min Kyung; Jeong, Ki-Heon

    2015-04-01

    Dilated pores can be an early sign of skin aging and are a significant cosmetic concern. The 1410-nm wavelength is optimal for superficial dermal treatments up to 650 μm deep. The aim of the present study was to evaluate the clinical effectiveness and safety of the fractional erbium-doped fiber 1410-nm laser in the treatment of dilated pores. Fifteen patients with dilated facial pores underwent three laser treatments at 3-week intervals. Posttreatment skin responses and side effects were assessed at treatment and follow-up visits by study physicians. Clinical effectiveness of treatment was assessed by both study physicians and patients 3 months after the final laser treatment using a quartile grading scale. Histological examination was performed using biopsy samples taken at baseline (pretreatment) and 3 months after the last treatment. This study showed that greater than 51 % improvement in dilated pores was demonstrated in 14 of 15 patients after three sessions of laser treatments. Improvements in skin texture, tone, and smoothness were reported in all patients. Treatment was well tolerated in all patients, with no unanticipated side effects. This study demonstrates that the 1410-nm fractional erbium fiber laser is effective and safe for treatment of dilated facial pores in Fitzpatrick skin types III-IV.

  6. 980 nm diode laser with automatic power control mode for dermatological applications

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Gelfond, Mark L.; Shatilova, Ksenia V.; Sosenkova, Svetlana A.; Lazareva, Anastasia A.

    2015-07-01

    Results of nevus, papilloma, dermatofibroma, and basal cell skin cancer removal by a 980+/-10 nm diode laser with "blackened" tip operating in continuous (CW) mode and automatic power control (APC) mode are compared. It was demonstrated that using APC mode decreases the width of collateral damage at removing of these nosological neoplasms of human skin. The mean width of collateral damage reached 0.846+/-0.139 mm for patient group with nevus removing by 980 nm diode laser operating in CW mode, papilloma - 0.443+/-0.312 mm, dermatofibroma - 0.923+/-0.271 mm, and basal cell skin cancer - 0.787+/-0.325 mm. The mean width of collateral damage reached 0.592+/-0.197 mm for patient group with nevus removing by 980 nm diode laser operating in APC mode, papilloma - 0.191+/-0.162 mm, dermatofibroma - 0.476+/-0.366 mm, and basal cell skin cancer - 0.517+/-0.374 mm. It was found that the percentage of laser wounds with collateral damage less than 300 μm of quantity of removed nosological neoplasms in APC mode is 50%, that significantly higher than the percentage of laser wounds obtained using CW mode (13.4%).

  7. Clinical Evaluation of Hair Removal Using an 810 nm Diode Laser With a Novel Scanning Device.

    PubMed

    Courtney, Erin; Goldberg, David J

    2016-11-01

    Diode lasers are often considered as the gold standard preference for hair removal due to the deep penetration and ef- fective targeting of the hair follicle. A wide variety of diode lasers are available, which can differ in terms of their parameters (such as fluence, pulse duration, repetition rate, scanner, and cooling). The objective of the study was to evaluate the safety and ef cacy of hair removal with an 810 nm novel scanning diode laser, up to six months after last treatment. A scanning 810 nm diode laser was used for axillary hair removal of 14 female patients who received 3 treatments, 4-6 weeks apart. Follow-up on hair count was conducted 3 and 6 months after last treatment and compared to baseline hair count. No unexpected or signi cant adverse events were recorded. An average hair count reduction of 72.8% after 3 months and 67.6% 6 months after the last treatment is demonstrated. The examined 810 nm diode laser was proven to be safe and effective for hair removal. Results were sustained for 6 months after last treatment. Longer follow-up data are followed for further substantiation of the clinical effect. Scanning technology can provide for potentially faster and safer treatments. J Drugs Dermatol. 2016;15(11):1330-1333..

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

    PubMed

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

    2015-12-01

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

  9. Mitochondrial dependent oxidative stress in cell culture induced by laser radiation at 1265 nm.

    PubMed

    Saenko, Yury V; Glushchenko, Eugenia S; Zolotovskii, Igor O; Sholokhov, Evgeny; Kurkov, Andrey

    2016-04-01

    Photodynamic therapy is the main technique applied for surface carcinoma treatment. This technique employs singlet oxygen generated via a laser excited photosensitizer as a main damaging agent. However, prolonged sensitivity to intensive light, relatively low tissue penetration by activating light the cost of photosensitizer (PS) administration can limit photodynamic therapy applications. Early was reported singlet oxygen generation without photosensitizer induced by a laser irradiation at the wavelength of 1250-1270 nm. Here, we study the dynamics of oxidative stress, DNA damage, changes of mitochondrial potential, and mitochondrial mass induced by a laser at 1265 nm have been studied in HCT-116 and CHO-K cells. Laser irradiation of HCT-116 and CHO-K cells has induced a dose-dependent cell death via increasing intracellular reactive oxygen species (ROS) concentration, increase of DNA damage, decrease of mitochondrial potential, and reduced glutathione. It has been shown that, along with singlet oxygen generation, the increase of the intracellular ROS concentration induced by mitochondrial damage contributes to the damaging effect of the laser irradiation at 1265 nm.

  10. Comparison of Bare-Tip and Radial Fiber in Endovenous Laser Ablation with 1470 nm Diode Laser

    PubMed Central

    Kurihara, Nobuhisa

    2014-01-01

    Objective: Major side effects after endovenous laser ablation (EVLA) are pain and bruising. The aim of this study was to compare outcome and side effects after EVLA for primary varicose veins with 1470 nm diode laser using bare-tip orradial fiber. Methods: From October 2007 to December 2010, 385 patients (453 limbs) with primary varicose veins treated with 1470 nm laser were studied. Bare-tip fiber was used in 215 patients (242 limbs) (BF group) and radial fiber (ELVeSTMRadial, Biolitec AG, Germany) was used in 177 patients (211 limbs) (RF group). This study is a retrospective study and radial fiber was started for use from November 2008. Laser energy was administered at 6–12 W of power in the BF group and 10 W of power in the RF group with constant pullback of laser fiber under tumescent local anesthesia. The patients were assessed by clinical examination and venous duplex ultrasonography at 24–48 h, one week, one month, 4 months and one year follow-up postoperatively. Results: Mean operating time, length of treated vein and linear endovenous laser energy of all cases were 42.6 min, 36.2 cm and 83.4 J/cm, respectively. Major complications such as deep vein thrombosis and skin burns were not noted. Bruising (1.9% vs. 19.4%) and pain (0.9% vs. 7.4%) were significantly lower in the RF group. Cumulative occlusion rates by Kaplan-Meier method were 100% at 32 months in the RF group and 99.5% at 4 years in the BF group. Conclusion: EVLA using 1470 nm laser with the radial fiber minimized adverse effects compared with bare-tip laser fiber. (*English translation of Jpn J Vasc Surg 2013; 22: 615-621) PMID:25298824

  11. Portable Raman spectroscopy using retina-safe (1550 nm) laser excitation

    NASA Astrophysics Data System (ADS)

    Brouillette, Carl; Smith, Wayne; Donahue, Michael; Huang, Hermes; Shende, Chetan; Sengupta, Atanu; Inscore, Frank; Patient, Michael; Farquharson, Stuart

    2012-06-01

    The use of portable Raman analyzers to identify unknown substances in the field has grown dramatically during the past decade. Measurements often require the laser beam to exit the confines of the sample compartment, which increases the potential of eye or skin damage. This is especially true for most commercial analyzers, which use 785 nm laser excitation. To overcome this safety concern, we have built a portable FT-Raman analyzer using a 1550 nm retina-safe excitation laser. Excitation at 1550 nm falls within the 1400 to 2000 nm retina-safe range, so called because the least amount of damage to the eye occurs in this spectral region. In contrast to wavelengths below 1400 nm, the retina-safe wavelengths are not focused by the eye, but are absorbed by the cornea, aqueous and vitreous humor. Here we compare the performance of this system to measurements of explosives at shorter wavelengths, as well as its ability to measure surface-enhanced Raman spectra of several chemicals, including the food contaminant melamine.

  12. Influence of exposure to 980 nm laser radiation on the luminescence of Si:Er/O light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Karim, A.; Du, C.-X.; Hansson, G. V.

    2008-12-01

    Erbium (Er) codoping with oxygen (O) in Si is a well-known method for producing electroluminescent material radiating at 1.54 μm through a 4f shell transition of Er3+ ions. In this work the influence of exposure to 980 nm radiation on the electroluminescence (EL) of reverse biased Si:Er/O light-emitting diodes (LEDs), which give a strong room temperature 1.54 μm intensity, is presented and discussed. All the device layers, including Er/O doped Si sandwiched between two Si0.82Ge0.18 layers, have been grown on silicon on insulator substrates using molecular beam epitaxy and processed to fabricate edge emitting Si:Er/O waveguide LEDs. Electromagnetic mode confinement simulations have been performed to optimize the layer parameters for waveguiding. The temperature dependence of the 1.54 μm EL intensity exhibits an abnormal temperature quenching with a peak near -30 °C, and at -160 °C it has decreased by a factor of 5. However, irradiating the devices with a 980 nm laser gives an enhancement of the 1.54 μm EL intensity, which is more dramatic at low temperatures (e.g., -200 °C) where the quenched EL signal is increased up to almost the same level as at room temperature. The enhancement of the EL intensity is attributed to the photocurrent generated by the 980 nm laser, reducing the detrimental avalanche current.

  13. Ytterbium-doped fibre laser tunable in the range 1017 - 1040 nm with second-harmonic generation

    SciTech Connect

    Dontsova, E I; Kablukov, S I; Babin, Sergei A

    2013-05-31

    A cladding-pumped ytterbium-doped fibre laser has been tuned to shorter emission wavelengths (from 1040 to 1017 nm). The laser output power obtained has been compared to calculation results. We have studied frequency doubling of the laser in a KTiOPO{sub 4} (KTP) crystal with type II phase matching in the XY plane and demonstrated wavelength tuning in the range 510 - 520 nm. (lasers)

  14. A InGaN/GaN quantum dot green ({lambda}=524 nm) laser

    SciTech Connect

    Zhang Meng; Banerjee, Animesh; Lee, Chi-Sen; Hinckley, John M.; Bhattacharya, Pallab

    2011-05-30

    The characteristics of self-organized InGaN/GaN quantum dot lasers are reported. The laser heterostructures were grown on c-plane GaN substrates by plasma-assisted molecular beam epitaxy and the laser facets were formed by focused ion beam etching with gallium. Emission above threshold is characterized by a peak at 524 nm (green) and linewidth of 0.7 nm. The lowest measured threshold current density is 1.2 kA/cm{sup 2} at 278 K. The slope and wall plug efficiencies are 0.74 W/A and {approx}1.1%, respectively, at 1.3 kA/cm{sup 2}. The value of T{sub 0}=233 K in the temperature range of 260-300 K.

  15. Nd:YGG crystal laser at 1110 nm: a potential source for detecting carbon monoxide poisoning.

    PubMed

    Yu, Haohai; Wu, Kui; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang; Jiang, Minhua

    2011-04-01

    We demonstrated a laser-diode pumped Nd-doped yttrium gallium garnet crystal laser at 1110 nm for the first time to our knowledge. By suppressing the oscillation at about 1.06 μm, continuous-wave output power of 2.1 W at 1110 nm was achieved. With a Cr:YAG as the saturable absorber, the passive Q-switching performance at this wavelength was obtained. The shortest pulse width and largest pulse energy were 31.5 ns and 22.7 μJ, respectively. Laser radiation at this wavelength is an important source for detecting carbon monoxide poisoning by simple frequency doubling with a nonlinear crystal.

  16. Resonantly pumped Er:YAG laser Q-switched by topological insulator nanosheets at 1617 nm

    NASA Astrophysics Data System (ADS)

    Huang, Bin; Tang, Pinghua; Yi, Jun; Jiang, Guobao; Liu, Jun; Zou, Yanhong; Zhao, Chujun; Wen, Shuangchun

    2017-09-01

    We demonstrated an in-band pumped 1617 nm Er:YAG solid-state laser passively Q-switched by self-assembled topological insulator Bi2Te3 nanosheets sandwiched by polymethyl methacrylate (PMMA) polymer. With the self-assembled Bi2Te3 saturable absorber, the laser can deliver Q-switched pulse centered at 1617 nm with a maximum single pulse energy 18.3 μJ for output power of 114 mW at repetition rate of 6.22 kHz and the maximum output power of 134 mW at a repetition rate of 11.6 kHz. The results suggest that the potential of topological insulator nonlinear modulator for broadband solid-state lasers applications.

  17. High repetition rate gain-switched Er:YAG ceramic laser at 1645 nm

    NASA Astrophysics Data System (ADS)

    Chen, B. H.; Zhang, J. N.; Zhao, Y. G.; Zhang, J.; Tang, D. Y.; Shen, D. Y.

    2016-02-01

    We report on a gain-switched Er:YAG ceramic laser resonantly pumped by an acousto-optically modulated Er, Yb co-doped fiber laser at 1532 nm. The laser produced stable pulse trains at 1645 nm with pulse repetition rate tunable between 13-100 kHz and corresponding pulse width of 480-450 ns under a pump power-level of 8.7 W. At the 100 kHz of repetition rate, over 2.2 W of average output power was generated for 6.5 W of incident pump power, corresponding to a slope efficiency of 40% with respect to incident pump power.

  18. Relationship between 578-nm (copper vapor) laser beam geometry and heat distribution within biological tissues

    NASA Astrophysics Data System (ADS)

    Ilyasov, Ildar K.; Prikhodko, Constantin V.; Nevorotin, Alexey J.

    1995-01-01

    Monte Carlo (MC) simulation model and the thermoindicative tissue phantom were applied for evaluation of a depth of tissue necrosis (DTN) as a result of quasi-cw copper vapor laser (578 nm) irradiation. It has been shown that incident light focusing angle is essential for DTN. In particular, there was a significant rise in DTN parallel to elevation of this angle up to +20 degree(s)C and +5 degree(s)C for both the MC simulation and tissue phantom models, respectively, with no further increase in the necrosis depth above these angles. It is to be noted that the relationship between focusing angles and DTN values was apparently stronger for the real target compared to the MC-derived hypothetical one. To what extent these date are applicable for medical practice can be evaluated in animal models which would simulate laser-assisted therapy for PWS or related dermatologic lesions with converged 578 nm laser beams.

  19. 193 nm Excimer laser processing of Si/Ge/Si(100) micropatterns

    NASA Astrophysics Data System (ADS)

    Gontad, F.; Conde, J. C.; Chiussi, S.; Serra, C.; González, P.

    2016-01-01

    193 nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3 μm diameter and around 25 nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240 mJ/cm2 lead to graded SiGe alloys with Si rich discs of 2 μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation.

  20. High power, 1060-nm diode laser with an asymmetric hetero-waveguide

    SciTech Connect

    Li, T; Zhang, Yu; Hao, E

    2015-07-31

    By introducing an asymmetric hetero-waveguide into the epitaxial structure of a diode laser, a 6.21-W output is achieved at a wavelength of 1060 nm. A different design in p- and n-confinement, based on optimisation of energy bands, is used to reduce voltage loss and meet the requirement of high power and high wall-plug efficiency. A 1060-nm diode laser with a single quantum well and asymmetric hetero-structure waveguide is fabricated and analysed. Measurement results show that the asymmetric hetero-structure waveguide can be efficiently used for reducing voltage loss and improving the confinement of injection carriers and wall-plug efficiency. (lasers)

  1. A 1014 nm linearly polarized low noise narrow-linewidth single-frequency fiber laser.

    PubMed

    Mo, Shupei; Xu, Shanhui; Huang, Xiang; Zhang, Weinan; Feng, Zhouming; Chen, Dongdan; Yang, Tong; Yang, Zhongming

    2013-05-20

    We present the demonstration of a compact linearly polarized low noise narrow-linewidth single-frequency fiber laser at 1014 nm. The compact fiber laser is based on a 5-mm-long homemade Yb(3+)-doped phosphate fiber. Over 164 mW stable continuous-wave single transverse and longitudinal mode lasing at 1014 nm has been achieved. The measured relative intensity noise is less than -135 dB/Hz at frequencies of over 2.5 MHz. The signal-to-noise ratio of the laser is larger than 70 dB, and the linewidth is less than 7 kHz, while the obtained linear polarization extinction ratio is higher than 30 dB.

  2. Experimental study of fs-laser induced sub-100-nm periodic surface structures on titanium.

    PubMed

    Nathala, Chandra S R; Ajami, Ali; Ionin, Andrey A; Kudryashov, Sergey I; Makarov, Sergey V; Ganz, Thomas; Assion, Andreas; Husinsky, Wolfgang

    2015-03-09

    In this work the formation of laser-induced periodic surface structures (LIPSS) on a titanium surface upon irradiation by linearly polarized femtosecond (fs) laser pulses with a repetition rate of 1 kHz in air environment was studied experimentally. In particular, the dependence of high-spatial-frequency-LIPSS (HSFL) characteristics on various laser parameters: fluence, pulse number, wavelength (800 nm and 400 nm), pulse duration (10 fs - 550 fs), and polarization was studied in detail. In comparison with low-spatial-frequency-LIPSS (LSFL), the HSFL emerge at a much lower fluence with orientation perpendicular to the ridges of the LSFL. It was observed that these two types of LIPSS demonstrate different fluence, shot number and wavelength dependencies, which suggest their origin is different. Therefore, the HSFL formation mechanism cannot be described by the widely accepted interference model developed for describing LSFL formation.

  3. Low intensity noise and narrow line-width diode laser light at 540 nm

    NASA Astrophysics Data System (ADS)

    Wang, Lirong; Tamaki, Ryo; Kasai, Katsuyuki; Okada-Shudo, Yoshiko; Watanabe, Masayoshi; Zhang, Yun

    2015-05-01

    We present a convenient method to generate high quality single-frequency green light at a wavelength of 540 nm. It consists of a noise suppressed external cavity diode laser at a wavelength of 1080 nm by optical filtering and resonant optical feedback, and a frequency doubling of the fundamental light with an a-cut KTP crystal. Highly efficient conversion is realized by type II non-critical phase matching. A stable single-frequency operation with a maximum power of about 20 mW is performed for more than 3 h. Both the intensity noise and line-width reach the level of a monolithic nonplanar ring laser, which is well known for its extraordinarily narrow line-width and extremely low noise among available single-frequency operating lasers.

  4. A split-face comparison study of pulsed 532-nm KTP laser and 595-nm pulsed dye laser in the treatment of facial telangiectasias and diffuse telangiectatic facial erythema.

    PubMed

    Uebelhoer, Nathan S; Bogle, Melissa A; Stewart, Brigitte; Arndt, Kenneth A; Dover, Jeffrey S

    2007-04-01

    Pulsed 595 nm and 532 nm lasers can effectively diminish or eliminate facial telangiectasia. We performed a split-face, single-blind, controlled, comparison study in an effort to determine their individual and comparative efficacy. Fifteen patients were treated using a 595-nm PDL on one side of the face and a pulsed 532-nm potassium-titanyl-phosphate (KTP) laser on the other. Each subject was evaluated at 3 weeks after three treatments. Both devices improved telangiectasia. The 532-nm device, however, was at least as effective or more effective than the 595-nm laser in all subjects. On average, the KTP laser achieved 62% clearing after the first treatment and 85% clearing 3 weeks after the third treatment, compared to 49% and 75% for the PDL, respectively. Seventy-nine percent of KTP laser-treated patients continued to have swelling for greater than 1 day versus 71% of PDL-treated patients. Of those patients who noted persistent erythema for at least 1 day after treatment, 58% noted more erythema on the KTP laser-treated side compared to 8% on the PDL-treated side. Both the 595-nm and the 532-nm pulsed lasers are highly effective in the treatment of facial telangiectasia and redness. The 532-nm KTP laser appears to be more effective but causes more swelling and erythema.

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

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  6. Frequency reproducibility of an iodine-stabilized Nd:YAG laser at 532 nm

    NASA Astrophysics Data System (ADS)

    Hong, Feng-Lei; Ishikawa, Jun; Zhang, Yun; Guo, Ruixiang; Onae, Atsushi; Matsumoto, Hirokazu

    2004-05-01

    We have established an ensemble of iodine-stabilized Nd:YAG lasers to verify the frequency reproducibility of the laser. The stability, repeatability and several systematic shifts of the laser frequency are investigated by heterodyne beating of the lasers. The frequency dispersion of the ensemble of lasers is evaluated to be 0.5 kHz (corresponding to a relative frequency uncertainty of 8 × 10 -13). The absolute frequency of one of the lasers (named as Y3) is measured to be 563 260 223 507 897(58) Hz using a femtosecond optical comb, when the laser was stabilized on the a10 component of the R(56)32-0 transition of 127I 2 for a cold-finger temperature of -10 °C. This group of lasers, including one transportable laser, forms an ensemble of optical frequency standards, which serves for many applications such as international comparisons, optical frequency measurements, frequency calibration services and high-resolution spectroscopy.

  7. Corneal injury threshold in rabbits for the 1540 nm infrared laser.

    PubMed

    Clarke, Thomas F; Johnson, Thomas E; Burton, Margaret B; Ketzenberger, Bryan; Roach, William P

    2002-08-01

    In the 40 yr since lasers were invented, they have become commonplace in military operations, and while their utility in this setting is undeniable, they also represent a potential hazard for those in contact with them. This threat must be recognized, information must be gathered to understand this injury potential, and the necessary measures must be taken to properly protect those who will work, train, and fight with these systems. The exact mechanisms of laser/tissue interaction at 1540 nm are not well understood. Previous studies and textbooks show remarkable disparity in reporting where 1540 nm laser energy is deposited and the quantity of energy required to cause tissue damage. Rabbit cornea is very similar histologically to that of humans with the exception that it lacks Bowman's membrane. This model has been recommended as a reasonable approximation by past researchers and avoids the use of valuable non-human, primate research animals. A rabbit model was used to demonstrate the ability of the 1540 nm laser to produce corneal injuries. Various energies were applied to find the threshold at which injury is consistently produced. Observations included the appearance of the injury in the rabbit cornea. All rabbits were between 5 and 6 kg. Corneal injury was consistent at energies above 56 J x cm(-2). Injuries involved the deeper corneal stroma rather than only the epithelial layer, thus raising concern for permanent visual disability in those affected. The gross appearance of these injuries was white opaque areas easily seen within the corneal stroma. Data shows conclusively that the 1540 nm laser causes significant corneal damage at reproducible energy levels. Further research is clearly necessary to advance our understanding of the role of Bowman's membrane, the healing properties of the injured cornea, and the epidemiology of laser injury.

  8. Spectroscopic study of carbon plasma produced by the first (1064 nm) and second (532 nm) harmonics of Nd:YAG laser

    SciTech Connect

    Hanif, M.; Salik, M.; Arif, F.

    2015-03-15

    In this research work, spectroscopic studies of carbon (C) plasma by using laser-induced breakdown spectroscopy (LIBS) are presented. The plasma was produced by the first (1064 nm) and second (532 nm) harmonics of a Q-switched Nd:YAG (Quantel Brilliant) pulsed laser having a pulse duration of 5 ns and 10-Hz repetition rate, which is capable of delivering 400 mJ at 1064 nm and 200 mJ at 532 nm. The laser beam was focused on the target material (100% carbon) by placing it in air at atmospheric pressure. The experimentally observed line profiles of five neutral carbon (C I) lines at 247.85, 394.22, 396.14, 588.95, and 591.25 nm were used to extract the electron temperature T{sub e} by using the Boltzmann plot method and determine its value, 9880 and 9400 K, respectively, for the fundamental and second harmonics of the laser, whereas the electron density N{sub e} was determined from the Stark broadening profile of neutral carbon line at 247.85 nm. The values of N{sub e} at a distance of 0.05 mm from the target surface for the fundamental-harmonic laser with a pulse energy of 130 mJ and the second-harmonic laser with a pulse energy of 72 mJ are 4.68 × 10{sup 17} and 5.98 × 10{sup 17} cm{sup −3}, respectively. This extracted information on T{sub e} and N{sub e} is useful for the deposition of carbon thin films by using the pulsed laser deposition technique. Moreover, both plasma parameters (T{sub e} and N{sub e}) were also calculated by varying the distance from the target surface along the line of propagation of the plasma plume and also by varying the laser irradiance.

  9. Depth of penetration of a 785nm wavelength laser in food powders

    NASA Astrophysics Data System (ADS)

    Chao, Kuanglin; Dhakal, Sagar; Qin, Jianwei; Kim, Moon S.; Peng, Yankun; Schmidt, Walter F.

    2015-05-01

    Raman spectroscopy is a useful, rapid, and non-destructive method for both qualitative and quantitative evaluation of chemical composition. However it is important to measure the depth of penetration of the laser light to ensure that chemical particles at the very bottom of a sample volume is detected by Raman system. The aim of this study was to investigate the penetration depth of a 785nm laser (maximum power output 400mw) into three different food powders, namely dry milk powder, corn starch, and wheat flour. The food powders were layered in 5 depths between 1 and 5 mm overtop a Petri dish packed with melamine. Melamine was used as the subsurface reference material for measurement because melamine exhibits known and identifiable Raman spectral peaks. Analysis of the sample spectra for characteristics of melamine and characteristics of milk, starch and flour allowed determination of the effective penetration depth of the laser light in the samples. Three laser intensities (100, 200 and 300mw) were used to study the effect of laser intensity to depth of penetration. It was observed that 785nm laser source was able to easily penetrate through every point in all three food samples types at 1mm depth. However, the number of points that the laser could penetrate decreased with increasing depth of the food powder. ANOVA test was carried out to study the significant effect of laser intensity to depth of penetration. It was observed that laser intensity significantly influences the depth of penetration. The outcome of this study will be used in our next phase of study to detect different chemical contaminants in food powders and develop quantitative analysis models for detection of chemical contaminants.

  10. Investigation of GaAs photoconductive switches triggered by 900nm semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Ma, Deming; Shi, Wei; Ma, Xiangrong; Wang, Xinmei; Pei, Tao

    2008-12-01

    Experiment of a lateral semi-insulating GaAs photoconductive semiconductor switch (SI-GaAs PCSS) with different electrode gaps triggered by 900nm semiconductor laser is reported. With the biased voltage of 0.2KV~3.0KV, the linear electrical pulse is outputted by SI-GaAs PCSS. When laser energy is very low, the semi-insulating GaAs PCSS with 1.5mm electrode gap is triggered by laser pulse, the output electrical pulse samples is instable. When the energy of the laser increases, the amplitude and the width of the electrical pulse also increase. It indicates that a stable electrical pulse is obtained while laser energy is high. With the biased voltage of 2.8kV, the SI-GaAs PCSS with 3mm electrode gap is triggered by laser pulse about 10nJ in 200ns at 900nm. The SI-GaAs PCSS switches a electrical pulse with a voltage up to 80V. The absorption mechanism by Franz-Keldysh effect under high-intensity electric field and EL2 deep level defects is discussed.

  11. Pulsed Yb:YAG thin disk laser with 100 W at 515 nm

    NASA Astrophysics Data System (ADS)

    Hollemann, G.; Heist, P.; Heinitz, S.; Symanowski, J.; Eidam, T.; Stolzenburg, C.; Giesen, A.

    2007-02-01

    Pulsed lasers with high average output power in the green spectral range are of interest for laser annealing applications. In this paper an efficient pulsed diode-pumped Yb:YAG thin disk laser with intracavity frequency doubling is presented. The Yb:YAG laser crystal disk has a thickness of 180 μm and a diameter of 10 mm and is pumped by a laser diode stack at a wavelength of 938 nm. The disk is soldered to a water-cooled Cu-W heat sink and exhibits a nearly perfect spherical surface. The folded resonator is dynamically stable with a beam factor of M2 = 5 and which is matched to the requirements of the application. Acousto-optical and electro-optical switches are investigated to operate the laser in the cavity-dumping mode. An average output power of 150 W at 515 nm is achieved. The diode-to-green efficiency is about 28%. A critically phase matched LBO crystal is used for intracavity second harmonic generation. We show that stable pulsing is obtained from 10 kHz to 150 kHz. The pulse-width can be varied from 200 ns to 700 ns by control of the low-loss period of the switching element. The experimental results are compared with theoretical modeling of the system and first application results are discussed.

  12. 760nm: a new laser diode wavelength for hair removal modules

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  13. Wound treatment on a diabetic rat model by a 808 nm diode laser

    NASA Astrophysics Data System (ADS)

    Lau, Pik Suan; Bidin, Noriah; Krishnan, Ganesan; AnaybBaleg, Sana Mohammed; Marsin, Faridah M.; Sum, Mohamad Bin Md; Baktiar, Harzi; Nassir, Zaleha; Lian Chong, Pek; Hamid, Asmah

    2015-07-01

    This paper presents a study on the effect of laser irradiation on wound healing. 808 nm diode laser was employed to facilitate the healing of impaired wounds in experimental diabetes using a rat model. Diabetes was induced in male rats by a streptozotocin injection with a dose of 60 mg kg-1. The disease was verified via measurement of the blood glucose level, which was set having 20 mmol L-1 stability. The rats were randomly distributed into two groups; one served as a control group and the other group was treated with the laser. The power density of the laser used was 0.5 W cm-2 and the wounds were treated for 8 d with the contact time of one second daily. The energy density used was 0.5 J cm-2. The healing progress was recorded via a digital camera. The recorded images were then transferred into Inspector Matrox and image J programs for the accurate measurement of the healing area. The tissue details of the wound were studied through histology. The wound contraction rate of laser therapy group was found to be two times faster than control group. This indicates that the 808 nm diode laser can accelerate the wound healing process.

  14. Second (1178 nm) and third (1242 nm) Stokes Raman fiber lasers without intermediate Stokes cavities

    NASA Astrophysics Data System (ADS)

    Mejía, E. B.; Juárez-Hernández, M.; De la Cruz-May, L.

    2017-07-01

    We report and propose a simple Raman fiber laser scheme that generates two or three order Raman Stokes components by using a single strong (unidirectional) cavity formed by a high-reflecting fiber Bragg grating and air-glass interface (fiber output); the intermediate cavities are non-grating, weak and bi-directional cavities that serve as ‘virtual links’ or energy reservoirs. Once the strong cavity reaches operation, it practically consumes (converts) all the energy from pump and intermediate components into a single and clamped (unidirectional) signal. For example, the use of second-Stokes fiber Bragg grating together with glass-air output operated and harvested practically all the energy. Analogously, third Stokes emission was obtained by changing the grating and hence relying on first and second non-grating formed intermediate cavities. The system uses commercial silica fiber and minimizes the use of lossy and costly fiber Bragg gratings. This proposal broadens the possibilities for covering the entire 1000-2000 nm window for applications that use silica fibers.

  15. Laser Phototherapy (660 nm) Can Be Beneficial for Reducing Gingival Inflammation in Prosthodontics

    PubMed Central

    Cardoso Bezerra, Sávio José; Fioranelli Vieira, Glauco; Eduardo, Carlos de Paula; de Freitas, Patrícia Moreira; Aranha, Ana Cecilia Corrêa

    2015-01-01

    Among the new technologies developed, low power lasers have enabled new approaches to provide conservative treatment. Low power lasers act at cellular level, resulting in reduced pain, modulating inflammation, and improved tissue healing. Clinical application of the low power laser requires specific knowledge concerning laser interaction with biological tissue so that the correct irradiation protocol can be established. The present case report describes the clinical steps involved in an indirect composite resin restoration performed in a 31-year-old patient, in whom low power laser was used for soft tissue biomodulation. Laser therapy was applied with a semiconductor laser 660 nm, spot size of 0.028 cm2, energy density of 35.7 J/cm2, mean power of 100 mW, and energy per point as 1 J, in contact mode, on a total of 2 points (mesial and distal), totaling 2 J of energy. The therapy with low power laser can contribute positively to the success of an indirect restorative treatment. PMID:26491573

  16. Extended coherence length Fourier domain mode locked lasers at 1310 nm.

    PubMed

    Adler, Desmond C; Wieser, Wolfgang; Trepanier, Francois; Schmitt, Joseph M; Huber, Robert A

    2011-10-10

    Fourier domain mode locked (FDML) lasers are excellent tunable laser sources for frequency domain optical coherence tomography (FD-OCT) systems due to their combination of high sweep rates, large tuning ranges, and high output powers. However, conventional FDML lasers provide coherence lengths of only 4-10 mm, limiting their use in demanding applications such as intravascular OCT where coherence lengths of >20 mm are required for optimal imaging of large blood vessels. Furthermore, like most swept lasers, conventional FDML lasers produce only one useable sweep direction per tunable filter drive cycle, halving the effective sweep rate of the laser compared to the filter drive frequency. Here, we demonstrate a new class of FDML laser incorporating broadband dispersion compensation near 1310 nm. Elimination of chromatic dispersion in the FDML cavity results in the generation of forward (short to long wavelength) and backward (long to short wavelength) sweeps with substantially identical properties and coherence lengths of >21 mm. This advance enables long-range, high-speed FD-OCT imaging without the need for optical buffering stages, significantly reducing laser cost and complexity.

  17. Subsurface defects of fused silica optics and laser induced damage at 351 nm.

    PubMed

    Hongjie, Liu; Jin, Huang; Fengrui, Wang; Xinda, Zhou; Xin, Ye; Xiaoyan, Zhou; Laixi, Sun; Xiaodong, Jiang; Zhan, Sui; Wanguo, Zheng

    2013-05-20

    Many kinds of subsurface defects are always present together in the subsurface of fused silica optics. It is imperfect that only one kind of defects is isolated to investigate its impact on laser damage. Therefore it is necessary to investigate the impact of subsurface defects on laser induced damage of fused silica optics with a comprehensive vision. In this work, we choose the fused silica samples manufactured by different vendors to characterize subsurface defects and measure laser induced damage. Contamination defects, subsurface damage (SSD), optical-thermal absorption and hardness of fused silica surface are characterized with time-of-flight secondary ion mass spectrometry (TOF-SIMS), fluorescence microscopy, photo-thermal common-path interferometer and fully automatic micro-hardness tester respectively. Laser induced damage threshold and damage density are measured by 351 nm nanosecond pulse laser. The correlations existing between defects and laser induced damage are analyzed. The results show that Cerium element and SSD both have a good correlation with laser-induced damage thresholds and damage density. Research results evaluate process technology of fused silica optics in China at present. Furthermore, the results can provide technique support for improving laser induced damage performance of fused silica.

  18. Optimal irradiance for sintering of inkjet-printed Ag electrodes with a 532nm CW laser

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Hwang, Jun Young; Moon, Seung Jae

    2013-09-01

    Industrial solar cell fabrication generally adopts printing process to deposit the front electrodes, which needs additional heat treatment after printing to enhance electrical conductivity. As a heating method, laser irradiation draws attention not only because of its special selectivity, but also because of its intense heating to achieve high electric conductivity which is essential to reduce ohmic loss of solar cells. In this study, variation of electric conductivity was examined with laser irradiation having various beam intensity. 532 nm continuous wave (CW) laser was irradiated on inkjet-printed silver lines on glass substrate and electrical resistance was measured in situ during the irradiation. The results demonstrate that electric conductivity varies nonlinearly with laser intensity, having minimum specific resistance of 4.1 x 10-8 Ωm at 529 W/cm2 irradiation. The results is interesting because the specific resistance achieved by the present laser irradiation was about 1.8 times lower than the best value obtainable by oven heating, even though it was still higher by 2.5 times than that of bulk silver. It is also demonstrated that the irradiation time, needed to finish sintering process, decreases with laser intensity. The numerical simulation of laser heating showed that the optimal heating temperature could be as high as 300 oC for laser sintering, while it was limited to 250 oC for oven sintering. The nonlinear response of sintering with heating intensity was discussed, based on the results of FESEM images and XRD analysis.

  19. Novel technique to treat melasma in Chinese: The combination of 2940-nm fractional Er:YAG and 1064-nm Q-switched Nd:YAG laser.

    PubMed

    Tian, Wei Cheng Brian Anthony

    2016-01-01

    Melasma is one of the most common pigmented lesions in Chinese women. Although topical therapies are the mainstay treatment, lasers are being used increasingly to treat pigmented lesions. Laser treatment of melasma is however still controversial. This is because lasers have not been able to produce complete clearance of melasma and recurrence rates are high. Laser treatments also cause complications such as hypopigmentation and post-inflammatory hyperpigmentation. In this article, we report on a novel technique using a combination of fractional 2940-nm Er:YAG and 1064-nm Q-switched Nd:YAG lasers. We achieved a rapid improvement in two cases of melasma in Chinese type III skin. The improvement was seen rapidly within a month of treatment. Follow-up at 6 months showed sustained results with no complications. This novel technique is able to safely confer excellent and sustained clearance within a short treatment time.

  20. Effectiveness of a 308-nm excimer laser in treatment of vitiligo: a review.

    PubMed

    Alhowaish, Alauldin Khalef; Dietrich, Nathalie; Onder, Meltem; Fritz, Klaus

    2013-05-01

    Vitiligo is a relatively common acquired disorder, characterized by progressive loss of melanocytes from the epidermis and the epidermal appendages. The disease is associated with considerable morbidity because of a major impact on the quality of life. The treatment for vitiligo is generally unsatisfactory and challenging. There are a variety of therapeutic possibilities including topical corticosteroids, topical calcineurin inhibitors, as well as phototherapy with Psoralen plus UVA (PUVA), narrow-band UVB, and a 308-nm excimer laser and/or lamps. Furthermore, surgical methods encompass grafting and transplantation while depigmentation treatments and psychological support may also be considered. The objective is to assess the effect of the 380-nm excimer laser in the treatment of vitiligo based on the available studies and case series. We searched the relevant literature about vitiligo and excimer laser published between 1990 and 2012 using the MEDLINE database. We reviewed all relevant articles about 308-nm excimer laser and light sources assessing their efficacy in the management of vitiligo as well as their side effects. The value of combination treatment methods was also analyzed. The available studies provide strong evidence that the excimer laser represents the most effective approach to treat vitiligo compared to ordinary phototherapy. Excimer laser is relatively safe and effective for localized disease. UV-sensitive areas respond best as well as a short duration of the disease. More frequent treatments achieve better results. Compared to other treatment modalities, the excimer laser most likely constitutes the treatment of choice for localized vitiligo. Its efficacy can be further improved in combination with other therapies such as corticosteroids, pimecrolimus, or tacrolimus.