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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 408 nm Laser System to Drive Stimulated Raman Transitions

    NASA Astrophysics Data System (ADS)

    Archibald, James, II; Erickson, Christopher; Durfee, Dallin

    2011-05-01

    We will discuss a diode laser system that produces two laser beams, differing in frequency by 1 GHz, that can be used to drive Raman transitions in 87Sr+. This system will be used to generate the π and π / 2 pulses in an ion interferometer. The laser consists of a grating stabilized master laser. This is then passed through an AOM and retroreflected back through the AOM in order to provide two frequency-shifted beams. These beams are then used to injection lock two slave lasers, in a scheme similar to the one described in. The AOM can be modulated with a stability better than 1 Hz. Thus we guarantee that the light output from the slaves is at a constant detuning, while drift from the master laser corresponds to common mode drift (to which the Raman transition is less sensitive). We will also discuss a technique used to improve laser stability similar to the scheme described in but using the measured impedance of the diode rather than the amplitude noise on the light to generate an error signal. We will discuss a diode laser system that produces two laser beams, differing in frequency by 1 GHz, that can be used to drive Raman transitions in 87Sr+. This system will be used to generate the π and π / 2 pulses in an ion interferometer. The laser consists of a grating stabilized master laser. This is then passed through an AOM and retroreflected back through the AOM in order to provide two frequency-shifted beams. These beams are then used to injection lock two slave lasers, in a scheme similar to the one described in. The AOM can be modulated with a stability better than 1 Hz. Thus we guarantee that the light output from the slaves is at a constant detuning, while drift from the master laser corresponds to common mode drift (to which the Raman transition is less sensitive). We will also discuss a technique used to improve laser stability similar to the scheme described in but using the measured impedance of the diode rather than the amplitude noise on the light to

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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 173Y b with a <50 Hz linewidth over 5 min, limited only by a residual frequency drift of some 0.1 Hz/s.

  5. 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.

  6. 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)

  7. LASER COOLING OF ATOMS: Study of transitions in thulium atoms in the 410-420-nm range for laser cooling

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    The possibility of laser cooling of thulium atoms is considered. The hyperfine structure of almost cyclic 4f136s2 (Jg = 7/2) <--> 4f125d3/26s2 (Je = 9/2) and 4f136s2 (Jg = 7/2) <--> 4f125d5/26s2 (Je = 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 4f136s6p (Je = 5/2) and 4f125d5/26s2 (Je = 7/2) levels is studied for the first time by this method. The decay probabilities of the Je = 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 = 6×107 s-1) is smaller than 2×10-5, 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 μm is discussed.

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

    PubMed

    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 (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(-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. PMID:25085123

  9. 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.

  10. 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.

  11. 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).

  12. 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.

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

    PubMed

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

    2016-05-01

    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 = 6.31t (0.66) [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

  14. 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

  15. 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. PMID:26371933

  16. 750 mW continuous-wave solid-state deep ultraviolet laser source at the 253.7 nm transition in mercury.

    PubMed

    Scheid, Martin; Markert, Frank; Walz, Jochen; Wang, Jiayu; Kirchner, Martin; Hänsch, Theodor W

    2007-04-15

    A high-power continuous-wave coherent light source at 253.7 nm is described. It is based on a solid-state Yb:YAG disk laser with two successive frequency doubling stages and is capable of generating stable output powers of up to 750 mW. Spectroscopy of the 6 (1)S(0)-6 (3)P(1) transition of mercury has been demonstrated. PMID:17375166

  17. Dependence of gain and laser power for Cu-II 780.8-nm transition on the diameter of a segmented hollow cathode discharge

    SciTech Connect

    Szalai, L.; Donko, Z.; Rozsa, K.; Tobin, R.C.

    1995-08-01

    The dependence of laser performance and discharge characteristics on the diameter of a segmented hollow cathode discharge for the Cu-II 780.8 nm transition is presented. This transition has a special importance since its upper level is common to potential CW VUV laser transitions (150--170 nm). Laser tubes with internal diameters of 2, 3, 4, and 5 mm were investigated. Decreasing the diameter resulted in an increased gain for a given current (up to 100%/m in the 2-mm diameter, 5-cm-long tube at 1-A current). The highest output power was obtained from the large-diameter tubes (20 mW from a 5-cm-long, 5-mm-diameter tube at 2-A current, without optimizing the output coupler). This work is a part of a series of investigations aimed at the optimization of the segmented hollow cathode discharge which has already been found to be the most efficient type of discharge for cathode sputtered metal ion lasers.

  18. 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.

  19. 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

  20. Characterizing temperature-dependent photo-oxidation to explain the abrupt transition from thermal to non-thermal laser damage mechanisms at 413 nm

    NASA Astrophysics Data System (ADS)

    Denton, Michael L.; Clark, C. D., III; Noojin, Gary D.; Estlack, Larry E.; Schenk, Adam C.; Burney, Curtis W.; Rockwell, Benjamin A.; Thomas, Robert J.

    2011-03-01

    Laser exposure duration dictates whether tissues subjected to short visible wavelengths ( <= 514 nm) are damaged by thermal (e.g. 0.1 s) or non-thermal ( >= 100 s) mechanisms. Somewhere between these extremes, an abrupt transition between the two damage mechanisms has been found for both in vitro and animal retinal models (J. Biomed. Opt. 15, 030512, 2010). Non-thermal (photochemical) damage is characterized by an inverse relationship between damage threshold irradiance and exposure duration (irradiance reciprocity). We have found that exposures of 40 - 60 s in an in vitro retinal model require radiant exposures well above the expected requirement for nonthermal damage, introducing the concept that damage was forced to be thermal in mechanism. Here we quantify and compare photo-oxidative processes at ambient temperatures between 35 - 50 °C.

  1. 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.

  2. 308nm excimer laser in dermatology.

    PubMed

    Mehraban, Shadi; Feily, Amir

    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

  3. 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.

  4. 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.

  5. 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%.

  6. 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.

  7. 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. PMID:21743558

  8. 1064-nm Nd:YAG laser nucleotomy

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.

    1993-07-01

    The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  15. 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.

  16. 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.

  17. 1085 nm Nd:YVO4 laser intracavity pumped at 914 nm and sum-frequency mixing to reach cyan laser at 496 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Yin, X. D.; Wang, D.; Zhang, X. H.

    2010-01-01

    We present for the first time a Nd:YVO4 laser at 1085 nm intracavity pumped at 914 nm by a Nd:YVO4 laser. We obtained intracavity powers of 57 W at 914 nm and 62 W at 1085 nm. Using type-I critical phase-matching LiB3O5 (LBO) crystal, a cyan laser at 496 nm is obtained by 914 and 1085 nm intracavity sum-frequency mixing. The maximum laser output power of 142 mW is obtained when an incident pump laser of 19.6 W is used.

  18. 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.

  19. The Double-ended 750 nm and 532 nm Laser Output from PPLN-FWM

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Yu-Xiang; Yao, Jian-Quan; Guo, Ling; Wang, Zhuo; Han, Sha-Sha; Zhang, Cui-Ying; Zhong, Kai

    2013-06-01

    We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things. A kind of optical maser is developed, in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd3+ :YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser. The laser outputs come from both left and right terminals. In the right branch, the laser goes into the right cycle polarization LinNbO3 (PPLN) crystal through the right coupler, produces the optical parametric oscillation and forms the signal light λ1 (1500 nm), the idle frequency light λ2 (3660.55 nm), and the second-harmonic of the signal light λ3 (750 nm). These three kinds of light and the pump light λ4 together form the frequency matching and the quasi-phase matching, then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm. Meanwhile, in the left branch, the laser goes into the left PPLN crystal through the left coupler, engenders frequency doubling and forms the light at wavelength 532 nm. That is to say, the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals, which is workable.

  20. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S; Kurkov, A S

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  1. 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.

  2. 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.

  3. 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

    2012-04-01

    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. PMID:22513602

  4. 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%.

  5. 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.

  6. Maskless pattern transfer using 355 nm laser

    NASA Astrophysics Data System (ADS)

    Gabran, S. R. I.; Mansour, R. R.; Salama, M. M. A.

    2012-05-01

    Low power near-ultraviolet laser can be employed in various pattern transfer techniques such as maskless lithography and organic film ablation. Laser maskless lithography allows rapid prototyping using thin as well as thick photoresist films. Non-photosensitive organic films can be patterned by laser ablation, and this technique is applied in creating micro-molds for metal deposition using electroplating and electroless deposition. This paper presents experimental results, a quantitative study and modeling of laser maskless processing using desktop Nd:YAG laser system using four different photoresists. Process variables were experimentally optimized to identify the appropriate laser parameters that would yield reliable and reproducible patterns. A finite element thermal model of the ablation process was created to investigate the effects of different substrate materials on the process quality.

  7. Absolute measurement of F2-laser power at 157 nm

    SciTech Connect

    Kueck, Stefan; Brandt, Friedhelm; Kremling, Hans-Albert; Gottwald, Alexander; Hoehl, Arne; Richter, Mathias

    2006-05-10

    We report a comparison of laser power measurements at the F2-laser wavelength oaf nm made at two facilities of the Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute. At the PTB laboratory at the electron storage ring BESSY II in Berlin, the scale for laser power was directly traced to a cryogenic radiometer operating at 157 nm, whereas at the PTB laser radiometry facility in Braunschweig the calibration of transfer detectors was performed with a newly developed standard for laser power at 157 nm, which is traceable in several steps to a cryogenic radiometer operating at 633 nm. The comparison was performed under vacuum conditions with laser pulse energies of?10 {mu}J, however with different average powers because different primary standard radiometers were used. The relative deviation for the responsivity of the transfer detector was 4.8% and thus within the combined standard uncertainty.

  8. Absolute frequency measurements and hyperfine structures of the molecular iodine transitions at 578 nm

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takumi; Akamatsu, Daisuke; Hosaka, Kazumoto; Inaba, Hajime; Okubo, Sho; Tanabe, Takehiko; Yasuda, Masami; Onae, Atsushi; Hong, Feng-Lei

    2016-04-01

    We report absolute frequency measurements of 81 hyperfine components of the rovibrational transitions of molecular iodine at 578 nm using the second harmonic generation of an 1156-nm external-cavity diode laser and a fiber-based optical frequency comb. The relative uncertainties of the measured absolute frequencies are typically $1.4\\times10^{-11}$. Accurate hyperfine constants of four rovibrational transitions are obtained by fitting the measured hyperfine splittings to a four-term effective Hamiltonian including the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions. The observed transitions can be good frequency references at 578 nm, and are especially useful for research using atomic ytterbium since the transitions are close to the $^{1}S_{0}-^{3}P_{0}$ clock transition of ytterbium.

  9. High power diode lasers emitting from 639 nm to 690 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

    2014-03-01

    There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

  10. 1064 nm laser emission of highly doped Nd: Yttrium aluminum garnet under 885 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Lupei, V.; Pavel, N.; Taira, T.

    2002-06-01

    Highly efficient 1064 nm continuous-wave laser emission under 885 nm diode pumping in concentrated Nd: Yttrium aluminum garnet (YAG) crystals (up to 3.5 at. % Nd) and ceramics (up to 3.8 at. % Nd) is reported. A highly doped (2.4 at. %) Nd:YAG laser, passively Q switched by a Cr4+:YAG saturable absorber, is demonstrated.

  11. 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.

  12. Scaling of laser-induced contamination growth at 266nm and 355nm

    NASA Astrophysics Data System (ADS)

    Ließmann, M.; Jensen, L.; Balasa, I.; Hunnekuhl, M.; Büttner, A.; Weßels, P.; Neumann, J.; Ristau, D.

    2015-11-01

    The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.

  13. Upconverted luminescence under 800 nm laser diode excitation in Nd 3+-activated fluoroaluminate glass

    NASA Astrophysics Data System (ADS)

    Koepke, Cz.; Wisniewski, K.; Sikorski, L.; Piatkowski, D.; Kowalska, K.; Naftaly, M.

    2006-01-01

    We report on the upconverted luminescence in neodymium-activated fluoroaluminate glass obtained with 800 nm diode laser excitation. Several anti-Stokes emissions: at 588, 607, 720 and 750 nm are observed and appropriate transitions are assigned. For both latter emissions we observe strong dependence on temperature: the 720 nm emission intensity decreases with temperature, whereas the 750 nm emission increases. Interpretations are presented in terms of the influence of oxygen-affected sites on the radiationless transitions and multiphonon anti-Stokes excitation. The models provide reasonable fits to the experimental data.

  14. Applications of combination wavelength (1060-nm and 530-nm) and pulsed Nd:YAG laser for contact laser surgery.

    PubMed

    Liu, K R; Peyman, G A; Myers, J D; Hamlin, S A; Katoh, N

    1989-01-01

    Two pulsed neodimium yittrium aluminum garnet (Nd:YAG) laser systems were evaluated for contact surgery through a fiberoptic system with a sapphire tip. Pulsed Nd:YAG laser at 1060 nm was as effective as continuous-wave Nd:YAG laser in producing tissue incisions. A combination of 1060-nm and 530-nm wavelengths achieved smooth cutting at lower energy levels. Corneal endothelial cell damage occurred at the high power level (7 watts) required for smooth underwater incisions with both continuous wave and pulsed lasers. PMID:2733255

  15. Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm

    SciTech Connect

    Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-07-31

    We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Extended tunability of Nd-doped fiber lasers operating at 872-936  nm.

    PubMed

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

    2015-09-01

    Efficient operation of an Nd-doped fiber laser operating in a wavelength-tunable configuration using a volume Bragg grating (VBG) is reported in this Letter. A high-power operation on the 4F3/2-4I9/2 transition of Nd3+ at short wavelengths below 900 nm is demonstrated for the first time in silica fibers. A high-efficiency (47% laser conversion) output power up to 22 W and a narrow linewidth of 0.035 nm are achieved. This configuration is compared with a more conventional fiber laser setup using a bandpass filter and a highly reflective dichroic mirror. PMID:26368721

  2. Highly efficient CW intracavity frequency-doubled Yb:YAG-LBO laser at 515 nm under 968 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Sun, G. C.; Li, Y. D.; Zhao, M.; Chen, X. Y.; Wang, J. B.; Chen, G. B.

    2011-05-01

    We describe the output performances of the 1030 nm transition in Yb:YAG under in-band pumping with diode laser at the 968 nm wavelength. An end-pumped Yb:YAG crystal yielded 1.93 W of continuous-wave (CW) output power for 9.1 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 23.6%. Furthermore, 205 mW 515 nm green light was acquired by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 2.7%. Comparative results obtained for the pump with diode laser at 940 nm are given in order to prove the advantages of the in-band pumping.

  3. 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.

  4. Measurement of Laser Damage Threshold of 355-nm Antireflection Coating

    NASA Astrophysics Data System (ADS)

    Tamura, Shigeharu; Kimura, Saburo; Sato, Yoshiyuki; Otani, Minoru; Yoshida, Hidetsugu; Yoshida, Kunio

    1989-06-01

    The laser damage thresholds of various types of antireflection (AR) coatings for an UV (355-nm) laser system were measured. Among them, the coatings consisting of two low-index materials, SiO2 and MgF2, had the highest average thresholds: 2.1 J/cm2 on fused silica substrates and 2.6 J/cm2 on sapphire substrates. The SiO2/MgF2 coating is hopeful for UV laser component.

  5. 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.

  6. Porcine dermal lesions produced by 1540-nm laser radiation pulses

    NASA Astrophysics Data System (ADS)

    Roach, William P.; Johnson, Thomas E.

    2001-07-01

    Completion of recent studies within our group indicates a breed-based difference in dermal response to 1540 nm 0.8 millisecond laser pulses. Laser exposure to Yucatan Mini- Pigs (highly pigmented skin) and Yorkshire pigs (lightly pigmented skin) demonstrate statistical differences between the ED50's of the two breeds. Laser delivery is accomplished using an Er:Glass system producing 1540 nm of light at millisecond exposure times and in the range of 5 to 95 J/cm2. Dermal lesion development was evaluated for acute, 1 hour, and 24-hour post exposure presentation. Our data contradicts the theory that water absorption is the sole mechanism of dermal tissue damage observed from 1540 nm laser exposures, as skin chromophores appear to play a role in lesion development.

  7. 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.

  8. 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...

  9. All-solid-state low noise Yb:YAG/LBO green laser at 515 nm

    NASA Astrophysics Data System (ADS)

    Liu, Qianqian; Yang, Min; Yao, Yi; Zhao, Ling; Li, Bin; Qu, Dapeng; Zheng, Quan

    2013-07-01

    We report the efficient compact green laser at 515 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode-pumped Yb:YAG laser on the transition at 1030 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. With the incident pump power of 10 W, 270 mW of CW output power at 515 nm is achieved with 15-mm-long LBO. The optical-to-optical conversion efficiency is 2.7%, and the power stability in 8 h is better than 2.36% with low noise.

  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. YSGG 2790-nm superficial ablative and fractional ablative laser treatment.

    PubMed

    Smith, Kevin C; Schachter, G Daniel

    2011-05-01

    The 2790-nm wavelength YSGG laser was introduced for aesthetic purposes under the trade name Pearl by Cutera in 2007. In clinical use, the Pearl superficial resurfacing laser has proved effective and well tolerated for the correction of superficial brown epidermal dyschromia and superficial fine lines and scars, and the Pearl Fractional laser produces excellent improvement in both dyschromia and improvement of deeper lines and moderately deep acne scarring. The two laser treatments can be combined in a single treatment session on different parts of the face or on the entire face, depending on patient needs and priorities. PMID:21763987

  12. 100 W average power femtosecond laser at 343 nm.

    PubMed

    Rothhardt, Jan; Rothhardt, Carolin; Müller, Michael; Klenke, Arno; Kienel, Marco; Demmler, Stefan; Elsmann, Tino; Rothhardt, Manfred; Limpert, Jens; Tünnermann, Andreas

    2016-04-15

    We present a femtosecond laser system delivering up to 100 W of average power at 343 nm. The laser system employs a Yb-based femtosecond fiber laser and subsequent second- and third-harmonic generation in beta barium borate (BBO) crystals. Thermal gradients within these BBO crystals are mitigated by sapphire heat spreaders directly bonded to the front and back surface of the crystals. Thus, a nearly diffraction-limited beam quality (M2 < 1.4) is achieved, despite the high thermal load to the nonlinear crystals. This laser source is expected to push many industrial and scientific applications in the future. PMID:27082370

  13. 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.

  14. Determination of transition probability for the 655-nm Tl line.

    NASA Astrophysics Data System (ADS)

    Karabourniotis, D.; Couris, S.; Damelincourt, J. J.

    Studies of high-pressure Hg-Tl I a.c. (50 Hz) arc plasmas have been used to verify the validity of Boltzmann statistics at the moment of maximum electron density (5 ms) by applying LTE criteria. For a known plasma temperature, the transition probability of the optically-thin 655-nm line of Tl was derived from emission measurements by using the self-reversed 535-nm line of Tl as reference [A655 = (3.74±0.37)×106s-1].

  15. 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.

  16. 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.

  17. 1064 nm Nd:YAG laser intracavity pumped at 946 nm and sum-frequency mixing for an emission at 501 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Jin, G. Y.; Wang, J. G.; Yin, X. D.; Zhang, A. F.

    2010-05-01

    We present for the first time a Nd:YAG laser emitting at 1064 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 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm.

  18. 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.

  19. High-efficiency direct-pumped Nd:YVO 4-LBO laser operating at 671 nm

    NASA Astrophysics Data System (ADS)

    Lü, Yan-Fei; Zhang, Xi-He; Xia, Jing; Yin, Xiao-Dong; Zhang, An-Feng; Bao, Lin; Lü, Wang

    2010-04-01

    The continuous-wave high-efficiency laser emission from Nd:YVO 4 at the fundamental wavelength of 1342 nm and its 671 nm second harmonic obtained by intra-cavity frequency doubling in an LBO nonlinear crystal are investigated under pumping by diode laser at 880 nm (on the 4F 3/2→ 4I 13/2 transition). The end-pumped Nd:YVO 4 crystal yielded a continuous-wave output power of 9.6 W at 1342 nm for 18.9 W of absorbed pump power. The slope efficiency measured with respect to the absorbed pump power is 60%. An output of 5.5 W at 671 nm was obtained by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 29%. Comparative results obtained for the pump with a diode laser at 808 nm (on the 4F 5/2→ 4I 13/2 transition) are given in order to prove the advantages of the 880 nm wavelength pumping.

  20. A compact efficient deep ultraviolet laser at 266 nm

    NASA Astrophysics Data System (ADS)

    Zhai, S. Y.; Wang, X. L.; Wei, Y.; Chen, W. D.; Zhuang, F. J.; Xu, S.; Li, B. X.; Fu, J. J.; Chen, Z. Q.; Wang, H. W.; Huang, C. H.; Zhang, G.

    2013-04-01

    We present a highly efficient and cost-effective watt-level deep-ultraviolet laser operating at 266 nm. Type-I phase-matching LBO crystals and type-I phase-matching BBO crystals were used for frequency doubling and fourth-harmonic generation, respectively. The highest 1.82 W average power of the 266 nm laser was obtained from nonlinear frequency conversion at a repetition rate of 30 kHz and a pump power of 18.8 W. The conversion efficiency from the diode to the deep-ultraviolet laser scales up to 10.7%. This is, to our knowledge, the highest efficiency ever reported generated from a laser diode single-end-pumped acousto-optic Q-switched system.

  1. 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).

  2. 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.

  3. Raman spectroscopy using 1550 nm (retina-safe) laser excitation.

    PubMed

    Brouillette, Carl; Huang, Hermes; Smith, Wayne; Farquharson, Stuart

    2011-05-01

    During the past decade, the use of portable Raman analyzers for field measurements has grown dramatically. However, most analyzers use 785 nm excitation lasers that can cause permanent eye damage. To overcome this safety concern, we have built a portable Fourier transform (FT) Raman analyzer using a 1550 nm retina-safe excitation laser and have compared its performance to our 1064 nm FT-Raman analyzer, which uses the same optical design. Raman theory predicts approximately five times lower peak intensities at 1550 nm. Although we found that intensities were as much as 20 times less intense, the analyzer is still capable of measuring spectra of sufficient quality to identify and differentiate chemicals. PMID:21513601

  4. 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.

  5. 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.

  6. An 885-nm Direct Pumped Nd:CNGG 1061 nm Q-Switched Laser

    NASA Astrophysics Data System (ADS)

    Li, Qi-Nan; Zhang, Tao; Feng, Bao-Hua; Zhang, Zhi-Guo; Zhang, Huai-Jin; Wang, Ji-Yang

    2014-07-01

    The 885 nm direct pumping method, directly into the 4F3/2 emitting level of Nd3+ ion, is used to a Nd:CNGG crystal to product passive Q-switched 1061 nm laser pulses, for the first time to the best of our knowledge. A maximum average output power of 1.16 W for 1061 nm Q-switched pulses and a repetition rate of 12.54 kHz are obtained. The pulse width is measured to be 24 ns and the peak power is 3.843 kW. A high-quality fundamental transverse mode can be observed owing to the reduction of the thermal effect for Nd:CNGG crystal by 885 nm direct pumping.

  7. Interaction between high power 532nm laser and prostatic tissue: in vivo evaluation for laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Malek, Reza; Kang, Hyun Wook; Peng, Steven Yihlih; Stinson, Douglas; Beck, Michael; Koullick, Ed

    2011-03-01

    A previous in vitro study demonstrated that 180W was the optimal power to reduce photoselective vaporization of the prostate (PVP) time for larger prostate glands. In this study, we investigated anatomic and histologic outcomes and ablation parameters of 180W laser performed with a new 750-μm side-firing fiber in a survival study of living canines. Eight male canines underwent anterograde PVP with the 180W 532-nm laser. Four each animals were euthanized 3 hours or 8 weeks postoperatively. Prostates were measured and histologically analyzed after hematoxylin and eosin (H&E), triphenyltetrazolium chloride (TTC), or Gomori trichrome (GT) staining. Compared to the previous 120W laser, PVP with the 180W laser bloodlessly created a 76% larger cavity (mean 11.8 vs. 6.7 cm3; p=0.014) and ablated tissue at a 77% higher rate (mean 2.3 vs. 1.3 cm3/min; p=0.03) while H&E- and TTC-staining demonstrated its 33% thicker mean coagulation zone (2.0+/-0.4 vs. 1.5+/-0.3 mm). H&E-stained cross-sectional prostatic tissue specimens from the 3-hour (acute) group showed histologic evolution of concentric non-viable coagulation zone, partially viable hyperemic transition zone of repair, and viable non-treated zone. H&E- and GT-stained specimens from the 8-week (chronic) group revealed healed circumferentially epithelialized, non-edematous, prostatic urethral channels with no increase in collagen in the subjacent prostatic tissue vis-á-vis the normal control. Our canine study demonstrates that 180W 532-nm laser PVP with its new fiber has a significantly higher ablation rate with a more hemostatic coagulation zone, but equally favorable tissue interaction and healing, compared with our previous 120W canine study.

  8. High power operation of a flashlamp-pumped Nd:YAG laser at 1123 nm

    NASA Astrophysics Data System (ADS)

    Lee, Hee Chul; Kim, Yong Pyung

    2010-04-01

    A high power flashlamp-pumped Nd:YAG laser at 1123 nm with a repetition rate of 40 Hz is investigated. Simple but specially coated resonator mirrors are adopted to suppress the parasitic oscillation at gain transition lines higher than 1123 nm. A maximum average output power of 40 W with an electrical pumping energy of 45.7 J and pumping pulse duration of 150 μs is achieved. To the best of our knowledge, the output power of 40 W at a wavelength of 1123 nm is the highest record up to now.

  9. 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.

  10. 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.

  11. 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. PMID:21403756

  12. Ultraviolet continuous-wave laser source at 205 nm for hydrogen spectroscopy

    NASA Astrophysics Data System (ADS)

    Galtier, Sandrine; Nez, François; Julien, Lucile; Biraben, François

    This paper reports on the generation of 15 mW of continuous narrow-band laser source at 205 nm. The infra-red light source provided by a Titanium-Sapphire (TiSa) laser is mixed with the fourth harmonic of a Nd:YVO4 laser by the use of a β-barium borate (BBO) non-linear crystal. This highly reliable and powerful ultraviolet (UV) source is an ideal tool for the 1S-3S hydrogen spectroscopy. Moreover, the wide tunability of the TiSa laser combined with this experimental set up makes the generation of bright deep ultra-violet (D-UV) sources possible. In particular, we plan to produce a 194 nm continuous light beam which is necessary to perform the 1S-4S transition in hydrogen.

  13. 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. PMID:19687946

  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. Ar-ion-laser-pumped infrared dye laser at 875-1084 nm

    SciTech Connect

    Kato, K.

    1984-12-01

    High-efficiency high-power cw dye-laser operation has been acheived from 875 to 1084 nm by pumping two styryl derivatives with an Ar-ion laser. Peak output powers as high as 900 and 750 mW were obtained around 925 and 980 nm, respectively.

  16. Demonstration of miniaturized 20mW CW 280nm and 266nm solid-state UV laser sources

    NASA Astrophysics Data System (ADS)

    Landru, Nicolas; Georges, Thierry; Beaurepaire, Julien; Le Guen, Bruno; Le Bail, Guy

    2015-02-01

    Visible 561 nm and 532 nm laser emissions from 14-mm long DPSS monolithic cavities are frequency converted to deep UV 280 nm and 266 nm in 16-mm long monolithic external cavities. Wavelength conversion is fully insensitive to mechanical vibrations and the whole UV laser sources fit in a miniaturized housing. More than 20 mW deep UV laser emission is demonstrated with high power stability, low noise and good beam quality. Aging tests are in progress but long lifetimes are expected thanks to the cavity design. Protein detection and deep UV resonant Raman spectroscopy are applications that could benefit from these laser sources.

  17. Spectroscopy of the 199Hg Optical Clock Transition at 265.5 nm

    NASA Astrophysics Data System (ADS)

    Lytle, Christian; Paul, Justin; Jones, R.

    2013-05-01

    Neutral Hg is an excellent candidate for a stable and accurate atomic clock. The doubly-forbidden clock transition at 265.5 nm can provide an extremely high-quality resonance factor (Q) when confined in an optical lattice at the Stark-shift free ``magic'' wavelength. A key feature of the Hg system is the expected reduced uncertainty of black-body radiation induced Stark shifts compared to other optically-based neutral atom clocks. We demonstrate precision spectroscopy of the 1S0 - 3P0 clock transition in 199Hg in a MOT. The MOT population of 106 atoms was depleted by over 70% using 3 mW from a cavity-stabilized probe laser tuned to the clock transition. We present our characterization of the transition and efforts to implement a stable Hg clock system.

  18. 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.

  19. 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.

  20. Laser enhancements for Lunar Laser Ranging at 532 nm

    NASA Astrophysics Data System (ADS)

    Martinot-Lagarde, G.; Aimar, M.; Albanèse, D.; Courde, C.; Exertier, P.; Fienga, A.; Mariey, H.; Métris, G.; Rigard-Cerison, R.; Samain, E.; Torre, J.-M.; Viot, H.

    This article exposes how we improved (by more than a factor of four) the green Lunar Laser Ranging instrumental sensitivity of the French telemetric station of the "Observatoire de la Côte d'Azur" in 2012. The primary reason for this success is the doubling of the pulse energy of our green Nd:YAG laser, reaching now 200 mJ at 10 Hz. This first gain is due to the replacement (inside our oscillator cavity) of the dye cell with a CR4+:YAG crystal saturable absorber. Complementary spatial beam profile improvements are also described, regarding polarisation, flashlamp geometry and specific lens arrangements (to exclude ghosts from focusing on the 8 m long amplification chain). Those combined laser enhancements pave the way to future science breakthrough linked to quasi-millimetric determination of the Earth-Moon dynamics (Murphy, 2013). Jointly, we propose an empirical thermal lensing model, varying with the cycle ratio of the flashlamps. Our model connects Koechner's (1970) continuous pumping to our intermittent pumping case, with a "normalised heating coefficient" equalling 0.05 only if the electrical lamp input power is equal to 6 kW and scaling as this [electrical input power into the lamps] to the power of [half the pumping cycle ratio].

  1. 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.

  2. Flash-lamp pumped Pr:YAP laser operated at wavelengths of 747 nm and 662 nm

    NASA Astrophysics Data System (ADS)

    Fibrich, Martin; Jelínková, Helena; Šulc, Jan; Nejezchleb, Karel; Škoda, Václav

    2009-02-01

    Successful room-temperature generation of Pr:YAP laser radiation at wavelengths of 747 nm and 662 nm was demonstrated. A flash-lamp pumped Pr:YAP laser was operated in free-running pulsed regime at room temperature. Permanent laser action was reached by means of a special UV color glass plate filter placed directly into the laser cavity. The maximum output energy and pulse length reached at wavelengths of 747 nm and 662 nm were 102 mJ, 92 μs and 6.1 mJ, 47.5 μs, respectively. The laser beam parameter M2 ~ 1.5 was measured when the 662 nm wavelength was generated. In the case of 747 nm wavelength generation, M2 ~ 1.2 was reached with a diaphragm inside the resonator. For different pumped energy values, the line shape and linewidth remained stable for both cases.

  3. 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

  4. Efficient 750-nm LED-pumped Nd:YAG laser.

    PubMed

    Huang, Kuan-Yan; Su, Cheng-Kuo; Lin, Meng-Wei; Chiu, Yu-Chung; Huang, Yen-Chieh

    2016-05-30

    We report an Nd:YAG laser pumped by light emission diodes (LEDs) at 750 nm. With 1% output coupling from a linear cavity containing a 2-cm long Nd:YAG crystal, the laser generated 37.5 μJ pulse energy at 1064 nm with M2 = 1.1 when pumped by 2.73-mJ LED energy in a 1-ms pulse at a 10 Hz rate. The measured optical and slope efficiencies for this linear-cavity laser are 1.36, and 9%, respectively. With 1 and 5% output couplings from a Z-cavity containing the same laser crystal, the lasers generated 346 and 288 μJ pulse energy with an optical efficiency of 3.4 and 2.8% and slope efficiency of 6.6 and 14%, respectively, for the same 1-ms pump pulse repeating at a 10 Hz rate. At the highest output from the Z-cavity, the measured M2 for the beam is 3.6. PMID:27410125

  5. 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.

  6. Pseudomorphic Single-Quantum-Well Lasers Emit At 980 Nm

    NASA Technical Reports Server (NTRS)

    Larsson, Anders; Forouhar, Siamak; Cody, Jeffrey G.; Lang, Robert J.; Andrekson, Peter A.

    1992-01-01

    Narrow-stripe semiconductor lasers emitting at 980 nm include pseudomorphic In0.2Ga0.8As/GaAs/AlxGa1-xAs graded-index-of-refraction, separate-confinement-heterostructure single quantum well(GRINSCH SQW) with overlaid ridge waveguide. 980 nm chosen as one that yields most efficient pumping because there is no absorption in excited states at this wavelength. Suitable for pumping Er(Sup3+)-doped optical-fiber amplifiers in optical-fiber communication systems and optical phased-array ranging systems.

  7. All solid-state continuous-wave Nd:YAG laser at 1319 and 659.5 nm under direct 885 nm pumping

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Yin, X. D.; Bao, L.; Quan, H.

    2010-01-01

    The continuous-wave high efficiency laser emission of Nd:YAG at the fundamental wavelength of 1319 nm and its 659.5-nm second harmonic obtained by intracavity frequency doubling with an LBO nonlinear crystal is investigated under pumping by diode laser at 885 nm (on the 4 F 3/2 → 4 I 13/2 transition). An end-pumped Nd:YAG crystal yielded 9.1 W at 1319 nm of continuous-wave output power for 18.2 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power is 0.55. Furthermore, 5.2 W 659.5 nm red light is acquired by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 0.286. Comparative results obtained for the pump with diode laser at 808 nm (on the 4 F 5/2 → 4 I 13/2 transition) are given in order to prove the advantages of the 885 nm wavelength pumping.

  8. Next generation 8xx nm laser bars and single emitters

    NASA Astrophysics Data System (ADS)

    Strauss, Uwe; Müller, Martin; Swietlik, Tomasz; Fehse, Robin; Lauer, Christian; Grönninger, Günther; König, Harald; Keidler, Markus; Fillardet, Thierry; Kohl, Andreas; Stoiber, Michael; Scholl, Iris; Biesenbach, Jens; Baeumler, Martina; Konstanzer, Helmer

    2011-03-01

    Semiconductor lasers with emission in the range 790 - 880 nm are in use for a variety of application resulting in different laser designs to fulfill requirements in output power, operation temperature and lifetimes. The output power is limited by self heating and catastrophic optical mirror damage at the laser facet (COMD). Now we present data on bars fabricated with our new facet technology, which enables us to double the maximum facet load. We present q-cw laser bar with 80% fill factor with increased power level to 350W in long term operation at 200μs and 100Hz. The COMD limit of the bar is as high as 680W. Using Quantel's optimized packaging stacks with 11 bars of 5mm widths are tested at up to 120A resulting over 66% power conversion efficiency at 1600W output power. Laser bars for continuous wave operation like 50% fill factor bars had an COMD limit of approx. 250W with conventional facet technology, the value is equivalent to 10W per 200μm emitter (conditions: 200μs). The new facet technology pushes the facet stability to 24W/emitter. The new process and an improved design enable us to shift continuous wave operation at 808nm from 100W to 150W/bar with lifetimes of several thousand hours at 30°C using DILAS mounting technology. Higher power is possible depending on lifetime requirements. The power conversion efficiency of the improved devices is as high as 62% at 200W cw. The next limitation of 8xxnm lasers is high temperature operation: Values of 60-80°C are common for consumer applications of single emitters. Therefore Osram developed a new epitaxial design which reduced the generation of bulk defects. The corresponding Osram single emitters operate at junction temperatures up to 95°C, a value which corresponds to 80°C heat sink temperature for lasers soldered on C-mount or 65°C case temperature for lasers mounted in TO can. Current densities of the single emitter broad area lasers are as high as 1.4kA/cm2 at 850nm emission wavelength.

  9. Laser-induced damage measurements with 266-nm pulses

    NASA Astrophysics Data System (ADS)

    Deaton, T. F.; Smith, W. L.

    1980-07-01

    Results of a survey of laser-induced damage thresholds for optical components at 266-nm are reported. The thresholds were measured at two pulse durations; 0.150 ns and 1.0 ns. The 30 samples tested include four commercial dielectric reflectors, three metallic reflectors, two anti-reflection films, a series of eight half-wave oxide and fluoride films, and twelve bare surfaces (fluoride crystals, silica, sapphire, BK-7 glass, cesium dideuterium arsenate and potassium dihydrogen phosphate). The 266-nm pulses were obtained by frequency-quadrupling a Nd:YAG, glass laser. Equivalent plane imagery and calorimetry were used to measure the peak fluence of each of the UV pulses with an accuracy of + or - of 15%; the uncertainty in the threshold determinations is typically + or - 30%.

  10. induced by 1,540-nm laser excitation

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Wang, X. F.; He, W. Y.; Bu, Y. Y.; Yan, X. H.

    2014-06-01

    The multi-photon ultraviolet upconversion emission properties and synergistic effect are investigated in BaSr2Y6O12:Er3+ phosphor. The deep-ultraviolet emissions centered at 274, 297 and 324-nm are observed under the 1,540-nm excitation, which results from a seven-, six- and six-photon upconversion process, respectively. A synergistic effect is found, which shows that the red emission intensity under 351- and 1,540-nm dual excitation is 4.7 % time stronger than the sum of red emission intensities under the 351 and 1,540-nm single excitation. This phenomenon is attributed to the 4I13/2 and 4I11/2 levels of Er3+ from non-radiative transition process under the 351-nm excitation are excited again to 4F9/2 level by absorbing 1,540-nm photon in the 351- and 1,540-nm dual-excitation process.

  11. 308-nm Excimer laser treatment of palmoplantar psoriasis.

    PubMed

    Goldberg, David J; Chwalek, Jennifer; Hussain, Mussarrat

    2011-04-01

    Psoriasis is a chronic inflammatory condition affecting 1-3% of the population. The incidence of palmoplantar involvement has been estimated to be between 2.8% and 40.9%. Significant psychosocial distress and difficulty performing activities of daily living can result. Treatment is often challenging. Traditional treatments include topical steroids, anthralin, calcipotriene, PUVA, methotrexate, cyclosporine, retinoids and biologics. In this case series, we report our success with the 308-nm excimer laser in the treatment of palmoplantar psoriasis. PMID:21401376

  12. 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.

  13. 980nm diode laser pump modules operating at high temperature

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  14. Femtosecond-pulse-driven 10-Hz 41.8-nm laser in Xe IX

    NASA Astrophysics Data System (ADS)

    Lemoff, B. E.; Yin, G. Y.; Gordon, C. L., III; Barty, C. P. J.; Harris, S. E.

    1996-01-01

    We report the observation of extreme UV lasing at 41.81 nm on the 4d95d1S0 - 4d95p1P1 transition in Xe IX, as proposed by Lemoff et al. [Opt. Lett. 19, 569 (1994)]. A 10-Hz circularly polarized 800-nm laser pulse with an energy of \\similar 70 mJ and a duration of \\similar 40 fs is longitudinally focused to a peak intensity of >3 \\times 1016 W / cm2 over a length of 8.4 nm in a differentially pumped cell containing 12 Torr of Xe gas. Laser amplification was observed with an estimated gain coefficient of 13 cm-1 and a total gain of exp(11).

  15. Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

    NASA Astrophysics Data System (ADS)

    Binetti, Simona; Le Donne, Alessia; Rolfi, Andrea; Jäggi, Beat; Neuenschwander, Beat; Busto, Chiara; Frigeri, Cesare; Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio

    2016-05-01

    Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p-n junction.

  16. Spectroscopic and laser properties of Tm3+ optical centers in CaF2 crystal under 795 nm diode laser excitation

    NASA Astrophysics Data System (ADS)

    Doroshenko, M. E.; Alimov, O. K.; Papashvili, A. G.; Martynova, K. A.; Konyushkin, V. A.; Nakladov, A. N.; Osiko, V. V.

    2015-12-01

    The dynamics of Tm3+ optical center formation with increasing thulium concentration and the influence of different optical centers on the fluorescence and laser properties of the 2 μm 3F4-3H6 transition under ~795 nm laser diode excitation is studied.

  17. All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

    NASA Astrophysics Data System (ADS)

    Zhu, P. F.; Li, B.; Liu, W. Q.; Liu, T. H.; Fang, C. X.; Zhao, Y.; Zheng, Q.

    2012-11-01

    An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.

  18. Ageing of optical components under laser irradiation at 532nm

    NASA Astrophysics Data System (ADS)

    Becker, S.; Delrive, L.; Bouchut, P.; Andre, B.; Geffraye, F.

    2005-09-01

    The pulsed Laser Induced Damage Threshold (LIDT) of optical components usually reaches several hundreds of MW/cm2. When exposed to laser power several order of magnitude below their LIDT, the optical component lifetime is, by default, considered infinite. Under specific conditions, the accumulation of laser pulses may lead to a contamination of the surface and a degradation of its optical properties and LIDT. In the first order, these phenomena depend on the experimental conditions such as the irradiation time, the laser power, and the environment. In order to better understand the physics emphasizing this degradation, we developed an experimental cell with an in-situ spectroscopic ellipsometry diagnostic. The dry-pumped cell sheltering the sample is associated with a mass spectrometer that enables us to follow the environmental conditions in which we experiment the ageing. Anti-reflection coatings on fused silica were tested under 10 kHz-532 nm laser ageing. We present first results of degradation obtained in these conditions.

  19. Efficiency intracavity frequency-doubled Nd:CNGG-LBO green laser at 530.5 nm under direct 885 nm pumping into the emitting level

    NASA Astrophysics Data System (ADS)

    Liu, W. M.; Zhang, X.

    2011-10-01

    We report an efficient laser emission on the 1061 nm 4 F 3/2 to 4 I 11/2 transition in Nd:CNGG under the pump with diode laser at 885 nm. Continuous wave (CW) 5.4 W output power at 1061 nm is obtained under 17.4 W of incident pump power; the slope efficiency with respect to the incident pump power was 36.2%. Moreover, intracavity frequency doubling with LiB3O5 (LBO) nonlinear crystal yielded 1.75 W of green light at 530.5 nm. An optical-to-optical efficiency with respect to the incident pump power was 10.1%.

  20. Highly efficient intracavity frequency-doubled Nd:GdVO4-LBO red laser at 670 nm under direct 880 nm pumping

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Yin, X. D.; Zhang, A. F.; Bao, L.; Wang, D.; Quan, H.

    2009-12-01

    We report the efficient compact red laser at 670 nm generation by intracavity frequency doubling of a continuous wave laser operation of a diode direct pumped Nd:GdVO4 laser on the 4 F 3/2 → 4 I 13/2 transition at 1340 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an absorbed pump power of 16.2 W, as high as 5.1 W of continuous wave output power at 670 nm is achieved with 15-mm-long LBO. The optical-to-optical conversion efficiency is up to 0.31, and the fluctuation of the red output power was better than 3.0% in the given 30 min. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing 4 F 5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.

  1. Drilling rate of five metals with picosecond laser pulses at 355, 532, and 1064 nm

    NASA Astrophysics Data System (ADS)

    Spiro, Alex; Lowe, Mary; Pasmanik, Guerman

    2012-06-01

    Experimental results on picosecond laser processing of aluminum, nickel, stainless steel, molybdenum, and tungsten are described. Hole drilling is employed for comparative analysis of processing rates in an air environment. Drilling rates are measured over a wide range of laser fluences (0.05-20 J/cm2). Experiments with picosecond pulses at 355 nm are carried out for all five metals and in addition at 532 nm, and 1064 nm for nickel. A comparison of drilling rate with 6-ps and 6-ns pulses at 355 nm is performed. The dependence of drilling rate on laser fluence measured with picosecond pulses demonstrates two logarithmic regimes for all five metals. To determine the transition from one regime to another, a critical fluence is measured and correlated with the thermal properties of the metals. The logarithmic regime at high-fluence range with UV picosecond pulses is reported for the first time. The energy efficiency of material removal for the different regimes is evaluated. The results demonstrate that UV picosecond pulses can provide comparable quality and higher processing rate compared with literature data on ablation with near-IR femtosecond lasers. A significant contribution of two-photon absorption to the ablation process is suggested to explain high processing rate with powerful UV picosecond pulses.

  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. 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.

  4. 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

  5. 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.

  6. 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)

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

    PubMed Central

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

    2013-01-01

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

  8. 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.

  9. 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.

  10. 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)

  11. 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. PMID:20372636

  12. Laser induced fluorescence (LIF) of Hg2 and Hg3 via dissociation of HgBr2 at 157 nm

    NASA Astrophysics Data System (ADS)

    Skordoulis, C.; Sarantopoulou, E.; Spyrou, S. M.; Kosmidis, C.; Cefalas, A. C.

    1991-06-01

    Laser induced fluorescence of the mercury clusters Hg2 and Hg3 in the spectral range between 300 nm to 510 nm has been obtained from the dissociation of HgBr2 at 7.88 eV (157.5 nm) with an F2 molecular laser, together with fluorescence from mercury atomic transitions from highly excited states. The excitation process involves two photon absorption which dissociates the molecule at 15.76 eV total photon energy with the subsequent formation of the metallic clusters.

  13. 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.

  14. 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.

  15. Optical trapping and cooling of 87Rb with a 1550 nm fiber laser

    NASA Astrophysics Data System (ADS)

    Olson, Abraham; Wang, Ping; Niffenegger, Robert; Ma, Qianli; Chen, Yong P.

    2011-05-01

    We have investigated optical trapping and cooling of 87Rb with a 1550nm single-frequency, fiber laser. We present a technique to map out the 3D spatial intensity profile of an optical dipole trap by imaging a background, untrapped cold atomic cloud. The 1550 nm laser causes a strong AC Stark shift [1] of the excited state (5P3/2) of 87Rb which we image by driving the D2 transition. Such Stark tomography allows us to use an untrapped cloud of 87Rb to characterize the potential trap depth, beam waist, trapping frequency, beam quality factor (M2), and astigmatism of the trap beam. We also investigated schemes for all-optical evaporative cooling of trapped atoms to quantum degeneracy.

  16. Next-generation 193-nm laser for sub-100-nm lithography

    NASA Astrophysics Data System (ADS)

    Duffey, Thomas P.; Blumenstock, Gerry M.; Fleurov, Vladimir B.; Pan, Xiaojiang; Newman, Peter C.; Glatzel, Holger; Watson, Tom A.; Erxmeyer, J.; Kuschnereit, Ralf; Weigl, Bernhard

    2001-09-01

    The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with

  17. 650 nm Laser stimulated dating from Side Antique Theatre, Turkey

    NASA Astrophysics Data System (ADS)

    Doğan, M.; Meriç, N.

    2014-03-01

    Samples were taken from the archeological excavation site, which was at the backs of the Side Antique Theatre. Samples were taken from under the base rock in this area. Polymineral fine grains were examined to determine the ages of the sediments. Samples gathered from the Side Antique Theatre were investigated through using the SAR method. Firstly, one part of the samples were evaluated by using conventional IRSL reading head model of (ELSEC-9010) which is infrared (880±80 nm) stimulation source with Schott BG39 filter. The IRSL age dating with feldspar minerals, gives a number of overestimated or underestimated age values as a result. A new reading head was proposed with the following configuration attachments for overestimation of equivalent dose rates. Measurements were done with this newly designed red laser stimulating reading head which works with Elsec 9010 OSL age dating system. SAR measurements were performed by (650±10 nm) red laser light source with two Schott BG3 filters. With usage of the new designed reading head; closer results were obtained in comparision with the Antique Theatre's expected age range. Fading rates were taken into consideration and these corrections were also handled for true age results.

  18. 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.

  19. 1 W of 261 nm cw generation in a Pr 3+:LiYF 4 laser pumped by an optically pumped semiconductor laser at 479 nm

    NASA Astrophysics Data System (ADS)

    Ostroumov, Vasiliy; Seelert, Wolf

    2008-02-01

    The lack of blue pump sources for Pr-doped materials has been overcome with the recent progress in optically pumped semiconductor lasers (OPS) operating at 479 nm. The availability of reliable high power OPS pump lasers, makes Pr 3+-doped crystals ideal gain media for compact and efficient ultraviolet solid-state lasers with output power in the Watt range. We report on the scalability of a 522/261 nm Pr:YLF cw laser that is dual-end-pumped by two OPS lasers at 479 nm. At 9.6 W of incident pump power more than 4 W were obtained at 522 nm with a slope efficiency of 45%. Intracavity frequency doubling of 522 nm resulted in 1 Watt of cw UV output at 261 nm.

  20. Laser stabilization at 1536 nm using regenerative spectral hole burning

    NASA Astrophysics Data System (ADS)

    Sellin, P. B.; Strickland, N. M.; Böttger, T.; Carlsten, J. L.; Cone, R. L.

    2001-04-01

    Laser frequency stabilization giving a 500-Hz Allan deviation for a 2-ms integration time with drift reduced to 7 kHz/min over several minutes was achieved at 1536 nm in the optical communication band. A continuously regenerated spectral hole in the inhomogeneously broadened 4I15/2(1)-->4I13/2(1) optical absorption of an Er3+:Y2SiO5 crystal was used as the short-term frequency reference, while a variation on the locking technique allowed simultaneous use of the inhomogeneously broadened absorption line as a long-term reference. The reported frequency stability was achieved without vibration isolation. Spectral hole burning frequency stabilization provides ideal laser sources for high-resolution spectroscopy, real-time optical signal processing, and a range of applications requiring ultra-narrow-band light sources or coherent detection; the time scale for stability and the compatibility with spectral hole burning devices make this technique complementary to other frequency references for laser stabilization.

  1. 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.

  2. 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.

  3. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the < 40 nm tuning range make the laser a promising tool for medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  4. Coherence measurements of a transient 14.7-nm x-ray laser

    NASA Astrophysics Data System (ADS)

    Dunn, James; Smith, Raymond F.; Hubert, Sebastian; Fajardo, Marta; Zeitoun, Philippe; Hunter, James R.; Remond, Christian; Vanbostal, Laurent; Jacquemot, Sylvie; Nilsen, Joseph; Lewis, Ciaran L. S.; Marmoret, Remy; Shlyaptsev, Vyacheslav N.; Ravet, Marie-Francoise; Delmotte, Franck

    2003-12-01

    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 4d1S0 --> 4p1P1 lasing transition is determined to be ~400 µm (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 ~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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  6. Comparison of 1470nm laser and 1470nm laser heat head for ex-vivo kidney tissue cutting: a preliminary study

    NASA Astrophysics Data System (ADS)

    Zhou, Zhentian; Zhang, Lupeng; Liu, Jiafeng; Shun, Zhi; Li, Wenzhi; Liu, Zhuwen; Liang, Zhiyuan

    2014-11-01

    Purpose: Compare of the efficiency of 1470nm laser and 1470nm laser heat head for tissue cutting in vitro porcine kidney tissue . Method: We designed a laser heat head that convert laser energy into thermal energy by the absorbing materials. Fresh kidney tissue was harvested from a porcine and then placed on a turntable with constant speed . The same power of 1470nm laser and 1470nm laser heat head was used to cutting tissue, respectively .The cutting results and the range of thermal damage was compared after cutting . Result: Compared with 1470nm laser, 1470nm laser heat head's cutting traces is more smooth and the thermal damage area is very regular ,so it has smaller damage to deep tissue . Conclusion: The efficiency of laser heat head for tissue cutting was better. This study indicate that we might be able to make laser which the tissue have a low absorption coefficient about it to obtain good results for tissue cutting through the laser point heat source.

  7. 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.

  8. Diode-laser-pumped tunable 896-939.5-nm neodymium-doped fiber laser with 43-mW output power.

    PubMed

    Cook, A L; Hendricks, H D

    1998-05-20

    A diode-laser-pumped neodymium-doped fiber laser is presented. For a launched pump power of 85 mW, the fiber laser had a cw output power of 43 mW, which is approximately an order of magnitude greater output power than any previously reported diode-pumped neodymium fiber laser operating on the 4F(3/2)-4I(9/2) transition, which covers the 900-950-nm region. The fiber laser had a threshold power of 10 mW and a slope efficiency of 58% with respect to launched pump power. Tuning with a diffraction grating was obtained from 896 to 937 nm with narrow-band output powers as high as 32 mW. Emission was also obtained at 939.5 nm with use of a fiber Bragg grating as the output reflector. PMID:18273282

  9. 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.

  10. Laser Direct Writing of Long Period Fiber Grating by 800 NM Femtosecond Laser Pulses

    NASA Astrophysics Data System (ADS)

    Ruan, Shuangchen; Huang, Yi; Du, Chenlin; Yu, Yongqin

    Femtosecond laser pulses with ultrashort time duration and ultrahigh peak power can cause the refractive index change in transparent materials and micron scale machining precision. Long period fiber gratings (LPFGs) with different periods and different grating lengths in the standard single mode fiber were fabricated, using laser direct writing method, by femtosecond laser pulses with pulse width of 200 fs at a center wavelength of 800 nm in air. The transmission spectra were studied in the range of 1510 nm to 1610 nm. Two LPFGs with period of 400 μm, and 550 μm, respectively fabricated with same irradiation power of 275 mW, were shown. The loss peak of 1552 nm, the transmission loss of 16 dB and the FWHM of 20 nm were obtained when the period of LPFG was 400 μm, while the loss peak of 1588 nm, the transmission loss of 20 dB and the FWHM of 25 nm were achieved when the period of LPFG was 550 μm. According to the theory of mode field coupling for long period grating, it was indicated that the modulation of refractive index Δn was in the level of 10-2.

  11. Al-free active region laser diodes at 894 nm for compact Cesium atomic clocks

    NASA Astrophysics Data System (ADS)

    Von Bandel, N.; Bébé Manga Lobé, J.; Garcia, M.; Larrue, A.; Robert, Y.; Vinet, E.; Lecomte, M.; Drisse, O.; Parillaud, O.; Krakowski, M.

    2015-03-01

    Time-frequency applications are in need of high accuracy and high stability clocks. Compact industrial Cesium atomic clocks optically pumped is a promising area that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of laser diodes that are used for atomic pumping. 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 earth applications. This work will provide key experience for further space technology qualification. We are in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894nm (D1 line of Cesium) and 852nm (D2 line). The use of D1 line for pumping will provide simplified clock architecture compared to D2 line pumping thanks to simpler atomic transitions and larger spectral separation between lines in the 894nm case. Also, D1 line pumping overcomes the issue of unpumped "dark states" that occur with D2 line. The modules should provide narrow linewidth (<1MHz), very good reliability in time and, crucially, be insensitive to optical feedback. The development of the 894nm wavelength is grounded on our previous results for 852nm DFB. Thus, we show our first results from Al-free active region with InGaAsP quantum well broad-area lasers (100μm width, with lengths ranging from 2mm to 4mm), for further DFB operation at 894nm. We obtained low internal losses below 2cm-1, the external differential efficiency is 0.49W/A with uncoated facets and a low threshold current density of 190A/cm², for 2mm lasers at 20°C.

  12. Diode pumped Nd:Lu0.5Y0.5VO4-LBO red laser at 671 nm

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Liu, J. Y.; Zhang, Y. C.

    2012-03-01

    We report a efficient compact red laser at 671 nm generation by intracavity frequency doubling of a continuous wave laser operation of a diode pumped Nd:Lu0.5Y0.5VO4 laser on the 4 F 3/2-4 I 13/2 transition at 1342 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an absorbed pump power of 17.8 W, as high as 2.25 W of continuous wave output power at 671 nm is achieved with 10-mm-long LBO. The optical-to-optical conversion efficiency is up to 12.6%, and the fluctuation of the red output power was better than 3.6% in the given 30 min.

  13. 8.3 W diode-end-pumped continuous-wave Nd:YAG laser operating at 946-nm.

    PubMed

    Zhou, Rui; Zhang, Tieli; Li, Enbang; Ding, Xin; Cai, Zhiqiang; Zhang, Baigang; Wen, Wuqi; Wang, Peng; Yao, Jianquan

    2005-12-12

    This paper reports a diode-end-pumped continuous-wave (CW) Nd:YAG laser operating at 946-nm by utilizing the 4F3/2-4I9/2 transition. We demonstrated that at an incident pump power of 27.7 W, an output power of 8.3-W could be achieved with a slope efficiency of 33.5%. To the best of our knowledge, this is the highest CW output power at 946 nm generated by LD end-pumped Nd:YAG lasers. By using intracavity frequency doubling with an LBO crystal, we further obtained a 473-nm blue laser with an output power of 1.2 W, achieving an optical-to-optical conversion efficiency of 7.1% at a pump power of 16.9 W. The short-term power instability of the blue laser was less than 1 %. PMID:19503225

  14. 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. PMID:26421536

  15. 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.

  16. Demonstration of a 100 Hz Repetition Rate Soft X-Ray Laser and Gain-Saturated Sub-10 nm Table-Top Lasers

    NASA Astrophysics Data System (ADS)

    Rocca, J. J.; Reagan, B. A.; Wang, Y.; Alessi, D.; Wernsing, K.; Luther, B. M.; Curtis, M. A.; Berrill, M.; Martz, D.; Wang, S.; Yin, L.; Furch, F.; Woolston, M.; Patel, D.; Shlyaptsev, V. N.; Menoni, C. S.

    We report the first operation of a table-top soft x-ray laser at 100 Hz repetition rate. This gain saturated laser produces 0.15 mW average power in the 18.9 nm line of nickel-like molybdenum in the form of 1.5 μJ pulses. This is the highest average power reported to date from a compact coherent soft x-ray laser source operating at wavelengths shorter than 20 nm. The soft x-ray laser is excited by a diode-pumped chirped pulse amplification Yb:YAG laser that produces 1 J pulses of 5 ps duration. We have also demonstrated the efficient generation of sub-9 nm wavelength laser pulses of microjoule energy at 1 Hz repetition rate with a table-top laser. Gain-saturated lasing was obtained at 8.85 nm in nickel-like lanthanum ions. Isoelectronic scaling along the lanthanide series resulted in lasing at wavelengths as short as 7.36 nm. Simulations show that the collisionally broadened atomic transitions in these dense plasmas can support the amplification of sub-picosecond soft x-ray laser pulses.

  17. Analysis of laser produced plasmas of gold in the 1-7 nm region

    NASA Astrophysics Data System (ADS)

    Li, Bowen; Higashiguchi, Takeshi; Otsuka, Takamitsu; Yugami, Noboru; Dunne, Padraig; Kilbane, Deirdre; Sokell, Emma; O'Sullivan, Gerry

    2014-04-01

    Extreme ultraviolet (EUV) spectra from gold laser produced plasmas were recorded in the 1-7 nm region using two Nd:YAG lasers with pulse lengths of 150 ps and 10 ns, respectively, operating at a range of power densities. The maximum focused peak power density was 9.5 × 1013 W cm-2 for the former and 5.3 × 1012 W cm-2 for the latter. Two intense quasicontinuous intensity bands resulting from n = 4-n = 4 and n = 4-n = 5 unresolved transition arrays dominate the 4-5.5 and 1.5-3.6 nm regions of both spectra. Comparison with atomic structure calculations performed with the Cowan suite of atomic structure codes as well as consideration of previous experimental and theoretical results aided identification of the most prominent features in the spectra. For the ns spectrum, the highest ion stage that could be identified from the n = 4-n = 5 arrays was Au28+ while for the ps plasma the presence of significantly higher stages was deduced and lines due to 4d104f-4d94f2 transitions in Ag-like Au32+ give rise to the strongest observed features within the n = 4-n = 4 array while in the n = 4-n = 5 array it was possible to identify a number of previously unidentified spectral features as resulting from 4f-5g transitions in the spectra of Au XX to Au XXXIII.

  18. 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.}

  19. Stable, high-power, single-frequency generation at 532 nm from a diode-bar-pumped Nd:YAG ring laser with an intracavity LBO frequency doubler.

    PubMed

    Martin, K I; Clarkson, W A; Hanna, D C

    1997-06-20

    We obtained 2.5 W of single-frequency TEM(00) output at 532 nm using a Brewster-angled LBO crystal for intracavity second-harmonic generation in a diode-bar-pumped Nd:YAG laser. By inserting a thin uncoated étalon, the 1061.4-nm laser transition can be selected, generating 1.6 W of output at 530.7 nm. PMID:18253441

  20. 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)

  1. 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.

  2. 1319 nm and 1356 nm dual-wavelength operation of diode-side-pumped Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Wang, Zhi-chao; Zhang, Shen-jin; Yang, Feng; Zhang, Feng-feng; Yuan, Lei; He, Miao; Li, Jia-jia; Zhang, Xiao-wen; Zong, Nan; Wang, Zhi-min; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2016-05-01

    We report the first demonstration on a diode-side-pumped quasi continuous wave (QCW) dual-wavelength Nd:YAG laser operating at 1319 nm and 1356 nm. The resonator adopts symmetrical L-shaped flat-flat structure working in a thermally near unstable cavity. By precise coating on the cavity mirrors, the simultaneous oscillation at 1319 nm and 1356 nm is delivered. A maximum dual-wavelength output power of 9.4 W is obtained. The beam quality factor M2 is measured to be 1.9.

  3. 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.

  4. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 672 nm

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    An efficient and compact red laser at 672 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 1344 nm under the condition of suppression the higher gain transition near 1064 nm. With 38 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 672 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 25.3% and the output power stability in 8 h is better than 2.38%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 672 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1344 nm.

  5. All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    An efficient and compact red laser at 458 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 916 nm under the condition of suppression the higher gain transition near 1064 nm. With 30 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 458 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 32.0% and the output power stability in 8 hours is better than 2.35%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 458 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 916 nm.

  6. High power 1018 nm monolithic Yb3+-doped fiber laser and amplifier High power 1018 nm monolithic Yb3+-doped fiber laser and amplifier

    NASA Astrophysics Data System (ADS)

    Xiao, H.; Zhou, P.; Wang, X. L.; Guo, S. F.; Xu, X. J.

    2012-10-01

    In this letter high power monolithic 1018 nm fiber laser and amplifier are presented. The output characteristics of 1018 nm laser with amplified spontaneous emission (ASE) feedback, fiber Bragg gratings (FBG) reflectivity, gain fiber length and other parameters are experimentally investigated. The difference between 1018 and 1064 nm amplification are also compared in experiment. Based on these experimental results, we find viable approaches to improve the laser and amplifier's performances. 85 W 1018 nm fiber laser with a slope efficiency of 71% and 110 W 1018 nm fiber amplifier with the slope efficiency of 77% are achieved, both of which we believe are the highest output at this wavelength that ever reported in open detail.

  7. A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2-4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.

  8. 980-nm 14-pin butterfly module dual-channel CW QW semiconductor laser for pumping

    NASA Astrophysics Data System (ADS)

    Deng, Yun; Yan, Changling; Qu, Yi; Li, Hui; Wang, Yuxia; Gao, Xin; Qiao, Zhongliang; Li, Mei; Qu, Bowen; Lu, Peng; Bo, Baoxue

    2010-10-01

    Nowadays, with its mature progress, the 790 nm - 1000 nm wavelength semiconductor laser is widely used in the fields of laser machining, laser ranging, laser radar, laser imaging, laser anti-counterfeit, biomedical and etc. Best of all, the 980 nm wavelength laser has its widespread application in the pumping source of Er3+ -doped fiber amplifier, optic fiber gyroscopes and other devices. The output wavelength of the fiber amplifier which takes the 980 nm wavelength laser as its pumping source is between 1060 nm and 1550 nm. This type of laser has its extremely wide range of applications in optical communication and other fields. Moreover, some new application domains keep constantly being developed. The semiconductor laser with the dual-channel ridge wave guide and the 980 nm emission wavelength is presented in this paper. In our work, we fabricated Lasers with the using of multi-quantum well (MQW) wafer grew by MBE, and the PL-wavelength of the MQW was 970 nm. The standard photofabrication method and the inductively coupled plasma (ICP) etching technology are adopted in the process of making dual-channel ridge wave guide with the width of 4 μm and height of 830 nm. In the state of continuous work at room temperature, the laser could output the single mode beam of 70 mW stably under the current of 100 mA. The threshold current of the laser diode is 17 mA and the slope efficiency is 0.89 W/A. The 3 dB spectrum bandwidth of the laser beam is 0.2 nm. This laser outputs its beam by a pigtail fiber on which Bragg grating for frequency stabilization is carved. The laser diode, the tail fiber, and the built-in refrigeration and monitoring modules are sealed in a 14-pin butterfly packaging. It can be used directly as the pumping source of Er3+ - doped fiber amplifier or optic fiber gyroscopes.

  9. Phase transitions in femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Povarnitsyn, Mikhail E.; Khishchenko, Konstantin V.; Levashov, Pavel R.

    2009-03-01

    In this study we simulate an interaction of femtosecond laser pulses (100 fs, 800 nm, 0.1-10 J/cm 2) with metal targets of Al, Au, Cu, and Ni. For analysis of laser-induced phase transitions, melting and shock waves propagation as well as material decomposition we use an Eulerian hydrocode in conjunction with a thermodynamically complete two-temperature equation of state with stable and metastable phases. Isochoric heating, material evaporation from the free surface of the target and fast propagation of the melting and shock waves are observed. On rarefaction the liquid phase becomes metastable and its lifetime is estimated using the theory of homogeneous nucleation. Mechanical spallation of the target material at high strain rates is also possible as a result of void growth and confluence. In our simulation several ablation mechanisms are taken into account but the main issue of the material is found to originate from the metastable liquid state. It can be decomposed either into a liquid-gas mixture in the vicinity of the critical point, or into droplets at high strain rates and negative pressure. The simulation results are in agreement with available experimental findings.

  10. 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. PMID:19565537

  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. Diode-pumped CW frequency-doubled Nd:GSAG-LBO blue laser at 471 nm

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    We describe the output performances of the 942 nm 4F3/2 → 4I9/2 transition in Nd:GSAG under diode-laser pumping. An end-pumped Nd:GSAG crystal yielded 3.7 W of continuous-wave output power for 17.8 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 23.4%. Furthermore, with 17.8 W of diode pump power and the frequency-doubling crystal LiB3O5 (LBO), a maximum output power of 572 mW in the blue spectral range at 471 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 3.2%; the output power stability over 4 h is better than 4.1%.

  13. Diode-pumped quasi-three-level Nd:CLNGG laser at 928 nm

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    We describe the output performances of the 928 nm 4 F 3/2 → 4 I 9/2 transition in Nd:CLNGG under diode-laser pumping. An end-pumped Nd:CLNGG crystal yielded 1.3 W of continuous-wave output power for 17.8 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 11.2%. Furthermore, with 17.8 W of diode pump power and the frequency-doubling crystal LiB3O5 (LBO), a maximum output power of 260 mW in the blue spectral range at 464 nm has been achieved. The blue output power stability over 4 h is better than 3.2%.

  14. Microdrilling of metals using femtosecond laser pulses and high average powers at 515 nm and 1030 nm

    NASA Astrophysics Data System (ADS)

    Döring, S.; Ancona, A.; Hädrich, S.; Limpert, J.; Nolte, S.; Tünnermann, A.

    2010-07-01

    We investigate the microdrilling of metals (stainless steel, copper and tungsten) for two different wavelengths, 1030 nm and 515 nm, in the regime of femtosecond laser pulses. An ytterbium-doped fibre CPA system provides high pulse energies (up to 70 μJ) and high repetition rates (up to 800 kHz), corresponding to high average powers of about 50 W, for this experimental study.

  15. Properties of continuous-wave 1123 nm laser with diode-side-pumped Nd:YAG

    NASA Astrophysics Data System (ADS)

    Bai, F.; Wang, Q. P.; Liu, Z. J.; Zhang, X. Y.; Sun, W. J.

    2010-11-01

    Laser properties of diode-side-pumped Nd:YAG laser operating at 1123 nm are demonstrated. A 1.0 at % Nd-doped Nd:YAG rod with a size of Ø3 × 63 mm2 is used as the active medium. Both radial and tangential thermal focal lengths of this side-pumped Nd:YAG rod are determined under lasing condition. The results show that the bifocusing strength of 1123 nm laser is larger than that of 1164 nm laser, and 1123-nm thermal focal lengths are shorter than those of 1064-nm laser due to higher quantum defect. Laser output performances of 1123 nm in terms of stability, output power and beam quality influenced by pump power at different cavity lengths are also discussed with a convex-piano cavity.

  16. Feasibility of a 486 nm Fraunhofer laser source based on a 4F(sub 3/2) yields 4I(sub 9/2) neodymium laser

    NASA Astrophysics Data System (ADS)

    Hanson, F. E.; Katz, D. L.; Poirier, P.

    1992-03-01

    The objective of this research was to investigate the potential of a laser source based on the neodymium (4)F(sub 3/2) (yields) (4)I(sub 9/2) transition for operation at 486.1 nm, the H(sub beta) Fraunhofer wavelength. We characterized this transition in Nd:YAG. Also, we identified stimulated rotational Raman conversion in H2, D2, and HD as a critical step in such a system.

  17. Nanobumps on silicon created with polystyrene spheres and 248 or 308 nm laser pulses

    SciTech Connect

    Piparia, Reema; Rothe, Erhard W.; Baird, R. J.

    2006-11-27

    Huang et al. [Appl. Phys. Lett. 86, 161911 (2005)] formed arrays of nanobumps on a silicon substrate. They applied a 248 nm laser pulse to a surface monolayer of 1-{mu}m-diameter polystyrene spheres. The authors first replicated their experiment with 248 nm light. But when 308 nm pulses were applied instead, the nanobumps had a different shape and composition. At 248 nm, much of the laser light is absorbed in the polystyrene, which serves to quickly distort, melt, and ablate the sphere. At 308 nm, very little light is absorbed. The nanobumps from 248 nm radiation are organic polymers, while those formed with 308 nm pulses are silicon based.

  18. Optically pumped gas laser using electronic transitions in the NaRb molecule

    SciTech Connect

    Kaslin, V.M.; Yakushev, O.F.

    1983-12-01

    Laser superradiance was achieved for the first time as a result of an electronic transition in a diatomic heteronuclear molecule as a result of direct optical pumping. This superradiance was observed in the region of 670 nm due to a transition to the ground state X/sup 1/..sigma../sup +/ of the intermetallic alkali molecule NaRb pumped by radiation from a pulsed copper vapor laser (lambda = 510.6 nm).

  19. 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.

  20. Diode-pumped Yb:GSO-LBO laser at 544 nm

    NASA Astrophysics Data System (ADS)

    Wang, J. G.; Dong, Y.

    2011-12-01

    We report a green laser at 544 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1088 nm Yb:GSO laser under in-band diode pumping at 940 nm. An 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 17.8 W, as high as 444 mW of CW output power at 544 nm is achieved. The fluctuation of the green output power was better than 4.6% in the given 4 h.

  1. 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.

  2. Simultaneous Dual-Wavelength Operation of Nd-Doped Yttrium Orthovanadate Self-Raman Laser at 1175 nm and Undoped Gadolinium Orthovanadate Raman Laser at 1174 nm

    NASA Astrophysics Data System (ADS)

    Shen, Hongbin; Wang, Qingpu; Zhang, Xingyu; Zhang, Lei; Zhang, Chu; Chen, Xiaohan; Cong, Zhenhua; Bai, Fen; Liu, Zhaojun

    2013-04-01

    A diode-pumped actively Q-switched Nd-doped yttrium orthovanadate self-Raman emission at 1175 nm and undoped gadolinium orthovanadate Raman emission at 1174 nm dual-wavelength laser is demonstrated. With the pump power of 20.5 W and pulse repetition frequency of 20 kHz, the maximum dual-wavelength output power of 1.52 W was obtained, which contained a 0.71 W 1174 nm Raman laser component and a 0.81 W 1175 nm self-Raman laser component. The corresponding dual-wavelength Raman pulse width was 14.8 ns. Experimental results indicated that the dual-wavelength Raman laser with a small wavelength separation was effectively realized through simultaneous self-Raman and Raman shift.

  3. 83 W yellow—green laser at 556 nm from frequency-doubling of a Q-switched Nd:YAG laser at 1112 nm in LBO

    NASA Astrophysics Data System (ADS)

    Wang, Z. C.; Xu, J. L.; Bo, Y.; Peng, Q. J.; Xie, S. Y.; Xu, Y. T.; Yang, F.; Zhang, J. Y.; Cui, D. F.; Xu, Z. Y.

    2011-11-01

    We demonstrate a high power 556 nm yellow-green laser by intracavity frequency doubled of the diode-pumped 1112 nm Nd:YAG laser in a symmetrical L-shaped flat-flat cavity. The coatings of the resonator mirrors were carefully designed to achieve efficient operation of fundamental wavelength of the laser at 1112 nm. By using a type-II phase matching LBO nonlinear crystal as the frequency-doubler, the maximum output power of the 556 nm laser was measured to be as high as 83 W with a pulse repetition frequency (PRF) of 10 kHz under incident pump power of 1150 W, corresponding to an optical-to-optical conversion efficiency of about 7.2%. The fluctuation of output power was less than 2% over 30 min.

  4. 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.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

  7. 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.

  8. All-solid-state continuous-wave frequency-doubling Nd:YVO(4)/LBO laser with 2.35 W output power at 543 nm.

    PubMed

    Yao, Yi; Zheng, Quan; Qu, Dapeng; Gong, Xiangyu; Zhou, Kai; Liu, Yang; Zhao, Ling

    2009-12-01

    Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a cw diode-pumped Nd:YVO(4) laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 14.5 W of diode pump power and the frequency-doubling crystal LiB(3)O(5), as high as 2.35 W of cw output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 15.7%; the output power stability over 5 h is better than 2.56%. 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:YVO(4) laser at 1086 nm. PMID:19953186

  9. Wavelength stabilizer based on dual fiber Bragg gratings for 980nm Mini-uncooled pump laser

    NASA Astrophysics Data System (ADS)

    Hu, Shuangshuang; Li, Yi; Jiang, Qunjie; Wu, Bin; Yu, Xiaojing; Wang, Haifang

    2008-12-01

    High power 980nm pump lasers are the key components in optical fiber amplifier. Wavelength stability for 980nm Miniuncooled pump laser is required to maintain the amplifier's efficiency throughout its lifetime. In this paper, a new type of wavelength stabilizer for uncooled pump laser which utilizes two fiber Bragg gratings (FBGs) matched in wavelength, bandwidth, and reflectivity is presented. The characteristics of transmissivity and reflectivity for the dual FBGs stabilized 980nm pump laser are theoretically modeled and experimentally studied. The results show that the output spectral characteristics of the uncooled pump laser with the dual FBGs have been greatly improved. The laser module can work steadily over a wide temperature range from 0°C to 70°C, with 0.2nm wavelength shift, along with more than 45dB side mode suppression ratio, and less than 1.57nm spectral bandwidth.

  10. 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.

  11. 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.

  12. Study on the laser crystal thermal compensation of LD end-pumped Nd:YAG 1319 nm/1338 nm dual-wavelength laser

    NASA Astrophysics Data System (ADS)

    Sun, R.; Wu, C. T.; Yu, M.; Yu, K.; Wang, C.; Jin, G. Y.

    2015-12-01

    The thermal model of laser diode (LD) end-pumped Nd: YAG was established. We analyzed the thermal effect of the crystal during the generation of 1319 nm/1338 nm dual-wavelength laser. Together with the bonded and non-bonded Nd:YAG crystal characteristics, we proposed to consider the bonded crystal’s internal temperature distribution of the three axes abc for the first time. The results showed that, compared with the non-bonded crystals, the bonded crystals could effectively reduce the crystal temperature. It provided a theoretical basis to solve the problem related to the thermal effect of the laser crystal and improve the laser output performance. The Nd:YAG laser crystal thermal model in this article could be widely applicable to similar laser crystals. The results provide a method to analyze and evaluate bonding crystal thermal compensation effectiveness by establishing the Nd:YAG crystal’s temperature distribution.

  13. 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}.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  15. 456-nm deep-blue laser generation by intracavity frequency doubling of Nd:GdVO4 under 879-nm diode pumping

    NASA Astrophysics Data System (ADS)

    Gao, J.; Yu, X.; Li, X. D.; Chen, F.; Zhang, K.; Yan, R. P.; Yu, J. H.; Wang, Y. Z.

    2009-01-01

    We report on a simple, compact continuous-wave 456-nm laser by intracavity frequency doubling of an end-pumped Nd:GdVO4 laser on the 4 F 3/2 → 4 I 9/2 transition. A 5-mm-long, 0.2-at % Nd:GdVO4 bulk crystal is employed as the gain medium and the Nd3+ ion is directly pumped into the emitting level (4 F 3/2) by a novel 879-nm laser diode. Intracavity frequency doubling with a 15-mm-long LBO crystal and a 10-mm-long BiBO crystal in a linear cavity yield 56- and 118-mW single-ended blue outputs at the absorbed pump power of 11.9 W, respectively. The corresponding values are scaled to 286 and 391 mW, respectively, in a V-type cavity, with optical conversion efficiencies of 2.4 and 3.3% versus the absorbed pump power. The fluctuations of the 456-nm output power for both cases are less than 3% at the maximum output level.

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

    NASA Astrophysics Data System (ADS)

    Reagan, Brendan A.; Berrill, Mark; Wernsing, Keith A.; Baumgarten, Cory; Woolston, Mark; Rocca, Jorge J.

    2014-05-01

    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 λ = 13.9 nm and 20 μW at λ = 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.

  17. All-solid-state cw frequency-doubling Nd:YLiF4/LBO blue laser with 4.33 W output power at 454 nm under in-band diode pumping at 880 nm.

    PubMed

    Lü, Yanfei; Zhang, Xihe; Cheng, Weibo; Xia, Jing

    2010-07-20

    We generated efficient blue laser output at 454 nm by intracavity frequency doubling of a continuous-wave (cw) diode-pumped Nd:YLiF(4) (Nd:YLF) laser at 908 nm based on the (4)F(3/2)-(4)I(9/2) transition. With 32.8 W of incident pump power at 880 nm and the frequency-doubling crystal LiB(3)O(5), a level as high as 4.33 W of cw output power at 454 nm is achieved, corresponding to an optical conversion efficiency of 13.2% with respect to the incident pump power. To the best of our knowledge, this is the first blue laser at 454 nm generated by intracavity frequency doubling of a diode-pumped Nd:YLF. PMID:20648194

  18. 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.

  19. CW, single-frequency 229nm laser source for Cd-cooling by harmonic conversion

    NASA Astrophysics Data System (ADS)

    Kaneda, Yushi; Yarborough, J. M.; Merzlyak, Yevgeny

    2015-02-01

    More than 200mW of CW 229nm for Cd atom cooling application was generated by the 4th harmonic of a single frequency optically pumped semiconductor laser using a 10-mm long, Brewster-cut BBO crystal in an external cavity. With 650mW of 458nm input, 216mW of 229nm power was observed. Conversion efficiency from 458nm to 229nm was more than 33%.

  20. 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.

  1. Efficient laser action on the 342-nm band of molecular iodine using ArF laser pumping

    NASA Astrophysics Data System (ADS)

    Shaw, M. J.; Edwards, C. B.; Oneill, F.; Fotakis, C.; Donovan, R. J.

    1980-08-01

    Strong laser action on the 342-nm band of I2 has been obtained by transverse pumping I2/SF6 mixtures at 193 nm with an ArF laser. The highest output energy obtained was 230 mJ at an intrinsic energy conversion efficiency of approximately 30% equivalent to a photon efficiency of greater than 50%.

  2. 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.

  3. 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. PMID:22487444

  4. High-Efficiency 894-nm Laser Emission of Laser-Diode-Bar-Pumped Cesium-Vapor Laser

    NASA Astrophysics Data System (ADS)

    Zheng, Yujin; Niigaki, Minoru; Miyajima, Hirofumi; Hiruma, Teruo; Kan, Hirofumi

    2009-03-01

    We report a high-efficiency cesium-vapor laser with a high-gas-pressure (˜3-atm helium and 0.49-atm ethane) cell pumped by a high-power external-cavity laser-diode bar. Peak laser power of 12.1 W at 894 nm was obtained, when the absorbed peak pump power was 23.1 W. The achieved slope efficiencies with the incident pump power and the absorbed pump power were 33 and 81.7%, respectively.

  5. 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)

  6. Tunable millisecond narrow-band Nd:GSGG laser around 1336.6 nm for 27Al+ optical clock

    NASA Astrophysics Data System (ADS)

    Wang, M.-Q.; Zhang, F.-F.; Li, J.-J.; Wang, Z.-M.; Zong, N.; Zhang, S.-J.; Yang, F.; Yuan, L.; Bo, Y.; Cui, D.-F.; Peng, Q.-J.; Xu, Z.-Y.

    2016-05-01

    We developed a narrow-band, Nd:GSGG ring laser tunable around 1336.6 nm with a tuning range more than 24 pm. The maximum output energy is 0.26 J per pulse with a pulse width of 900 μs and a pulse repetition rate of 10 Hz. The root-mean-square of wavelength stability in 1 h is 0.27 pm, and M2 factor is 1.06 at the output energy of 0.16 J per pulse. It can be a good candidate of the fundamental laser, of which the eighth-harmonic generation at 167.0787 nm can be used to induce the 27Al+ ion by the 1S0↔1P1 transition for laser cooling when it is used as the medium for optical clock.

  7. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  9. Single-frequency distributed Bragg reflector Nd doped silica fiber laser at 930 nm.

    PubMed

    Fang, Qiang; Xu, Yang; Fu, Shijie; Shi, Wei

    2016-04-15

    We report a single-frequency distributed Bragg reflector (DBR) fiber laser at 930 nm for the first time, to the best of our knowledge. A ∼2.5 cm long commercial highly neodymium-doped silica fiber was utilized as the gain medium to achieve ∼1.9 mW laser output. The single longitudinal mode operation of this laser was verified by a scanning Fabry-Perot interferometer. This fiber laser is suited for seeding high-power 930 nm narrow-linewidth laser amplifiers, which can be used to generate coherent single-frequency pure blue light through frequency doubling. PMID:27082356

  10. 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

    2012-04-01

    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. PMID:22513615

  11. Isotope shifts and hyperfine structure of the laser-cooling Fe I 358-nm line

    NASA Astrophysics Data System (ADS)

    Huet, N.; Pettens, M.; Bastin, T.

    2015-11-01

    We report on the measurement of the isotope shifts of the 3 d74 s a 5F5-3 d74 p z 5G6o Fe i line at 358 nm between all four stable isotopes ,Fe56Fe54,Fe57 , and Fe58 , as well as the hyperfine structure of that line for Fe57 , the only stable isotope having a nonzero nuclear spin. This line is of primary importance for laser-cooling applications. In addition, an experimental value of the field and specific mass shift coefficients of the transition is reported as well as the hyperfine structure magnetic dipole coupling constant A of the transition excited state in Fe57 , namely A (3 d74 p z 5G6o) =31.241 (48 ) MHz. The measurements were carried out by means of laser-induced fluorescence spectroscopy performed on an isotope-enriched iron atomic beam. All measured frequency shifts are reported with relative uncertainties below one third percent.

  12. Efficient emission at 1908 nm in a diode-pumped Tm:YLF laser

    SciTech Connect

    Zakharov, N G; Antipov, Oleg L; Savikin, A P; Sharkov, V V; Eremeikin, O N; Frolov, Yu N; Mishchenko, G M; Velikanov, S D

    2009-05-31

    Emission parameters at 1908 nm in a longitudinally-diode-pumped Tm:YLF laser are studied. The laser parameters are optimised to obtain the maximal power of high-quality cw radiation. The output power of {approx}27 W is obtained at the slope efficiency of {approx}50% and total optical pump conversion efficiency of {approx}41%. (lasers and amplifiers)

  13. Bi-doped fiber lasers and amplifiers for a spectral region of 1300-1470 nm.

    PubMed

    Bufetov, Igor A; Firstov, Sergey V; Khopin, Vladimir F; Medvedkov, Oleg I; Guryanov, Alexey N; Dianov, Evgeny M

    2008-10-01

    Bismuth-doped fiber lasers operating in the range 1300-1470 nm have been demonstrated for the first time, to our knowledge. It has been shown that Bi-doped alumina-free phosphogermanosilicate fibers reveal optical gain in a wavelength range of 1240-1485 nm with pumping at 1205, 1230, or 808 nm. PMID:18830360

  14. 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

  15. An Optical Clock/Frequency Standard at 657 nm Based On Laser-Cooled Neutral Calcium

    NASA Astrophysics Data System (ADS)

    Oates, Chris

    2002-05-01

    Optical atomic clocks are receiving increased attention due to their enormous potential for high stability and accuracy, and because of the revolution in optical metrology that resulted from the development of fs-laser-based optical clockwork.(S. A. Diddams, T. Üdem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, Science 293, 825 (2001).) We have constructed a high performance diode-laser-based optical frequency reference that uses an intercombination line (400 Hz natural linewidth) in laser-cooled neutral Ca at 657 nm. Absolute frequency measurements against the Cs-based NIST time ensemble via fs-laser metrology have led to a determination of the clock frequency (456 THz) with 26 Hz uncertainty.(T. Üdem, S. A. Diddams, K. R. Vogel, C. W. Oates, E. A. Curtis, W. D. Lee, W. M. Itano, R. E. Drullinger, J. C. Bergquist, and L. Hollberg, Phys. Rev. Lett. 86, 4996 (2001).) Measurements of the short-term fractional frequency instability against a Hg^+ ion optical clock system (again via the fs-laser comb) yielded an upper limit of 6x10-15 @ 1 s. In order to improve these results by an order of magnitude or more, we are currently developing a second-stage cooling scheme for Ca. This approach uses quenched cooling with the narrow clock transition and can reduce the atomic temperature by nearly three orders of magnitude. Recent cooling results in one and three dimensions will be presented.

  16. 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.

  17. 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.

  18. Spectroscopy and laser cooling on the - line in Yb via an injection-locked diode laser at 1,111.6 nm

    NASA Astrophysics Data System (ADS)

    Kostylev, N.; Locke, C. R.; Tobar, M. E.; McFerran, J. J.

    2015-03-01

    We generate 555.8-nm light with sub-MHz linewidth through the use of laser injection locking of a semiconductor diode at 1,111.6 nm, followed by frequency doubling in a resonant cavity. The integrity of the injection lock is investigated by studying an offset beat signal between slave and master lasers, by performing spectroscopy on the transition in magneto-optically trapped ytterbium, and by demonstrating additional laser cooling of with the 555.8-nm light in a dual-wavelength magneto-optical trap (MOT). For the - spectroscopy, we confirm the linear dependence between ground-state linewidth and the intensity of an off-resonant laser, namely that used to cool Yb atoms in a - magneto-optical trap. A temperature of 60 μK is produced for in the dual-wavelength MOT. Our results demonstrate the suitability of injection-locked 1,100-1,130-nm laser diodes as a source for sub-MHz linewidth radiation in the yellow-green spectrum.

  19. 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.

  20. Sum frequency generation of UV laser radiation at 266  nm in LBO crystal.

    PubMed

    Nikitin, D G; Byalkovskiy, O A; Vershinin, O I; Puyu, P V; Tyrtyshnyy, V A

    2016-04-01

    We report experimental results of generation at 266 nm in LBO crystal by frequency mixing of the fundamental (1064 nm) and third harmonic (355 nm) of ytterbium pulsed fiber laser radiation. Deep ultraviolet (DUV) output power of 3.3 W at 266 nm was achieved with 14% IR-to-DUV conversion efficiency. UV-induced bulk degradation of LBO crystals was observed and visualized by the dark field method. PMID:27192312

  1. 500.5-nm blue-green laser based on sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Na, Y. X.

    2011-07-01

    We report for the first time a continuous-wave (CW) coherent radiation at 500.5 nm by intracavity sum-frequency generation of 1063 nm Nd:GdVO4 laser and 946 nm Nd:YAG laser. Blue-green laser is obtained by using a doubly cavity, type-II critical phase matching KTiOPO4 (KTP) crystal sum-frequency mixing. With total pump power of 27.8 W, TEM00 mode blue-green laser at 500.5 nm of 421 mW is obtained. At the output power level of 421 mW, the blue-green power stability is better than 2.8% and laser beam quality M 2 factor is 1.37.

  2. 504 nm blue-green laser based on sum-frequency mixing of diode pumped Nd3+ lasers

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Jin, G. Y.; Dong, Y.

    2011-08-01

    We report for the first time a continuous-wave (CW) blue-green radiation at 504 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1080 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 504 nm blue-green laser was obtained by 946 and 1080 nm intra-cavity sum-frequency mixing, and output power of 215 mW was demonstrated. At the output power level of 215 mW, the output power stability is better than 4.7% and laser beam quality M2 factor is 1.21.

  3. High-power output of ytterbium-doped oxyorthosilicate lasers at 1018 nm

    NASA Astrophysics Data System (ADS)

    Lin, Niannian; Li, Wenxue; Zhou, Yuan; Shi, Yi; Yan, Ming; Yang, Kangwen; Zhao, Jian; Yang, Xianghui; Zeng, Heping

    2013-01-01

    A high-power laser system at 1018 nm was realized with an ytterbium-doped oxyorthosilicate solid-state master oscillator and ytterbium-doped double-clad fiber amplifier. In the Yb:LSO (Yb:Lu2SiO5) and Yb:LYSO (Yb:LuYSiO5) master laser oscillator, we attained the broadest tunable wavelength range from 994.50 to 1094.22 nm. In the power amplifier, we achieved an output power up to 4.14 W at 1018 nm by amplifying the Yb:LSO laser under a pump power of 15.8 W.

  4. Comparing 1470- and 980-nm diode lasers for endovenous ablation treatments.

    PubMed

    Aktas, Aykut Recep; Celik, Orhan; Ozkan, Ugur; Cetin, Mustafa; Koroglu, Mert; Yilmaz, Sevda; Daphan, Birsen U; Oguzkurt, Levent

    2015-07-01

    The purpose of this study was to compare the effectiveness of 1470- and 980-nm lasers with regard to power output, complications, recanalization rates, and treatment response. We prospectively evaluated the effectiveness of endovenous laser ablation (EVLA) in a total of 152 great and small saphenous veins from 96 patients. Lasers were randomly used based on the availability of the units. Patients were clinically evaluated for Clinical Etiologic Anatomic Pathophysiologic (CEAP) stage and examined with Doppler ultrasound. Treatment response was determined anatomically by occlusion of the vein and clinically by the change in the venous clinical severity score (VCSS). Seventy-eight of the saphenous veins underwent EVLA with a 980-nm laser and 74 underwent EVLA with a 1470-nm laser. Treatment response was (68) 87.2 % in the 980-nm group and (74) 100 % in the 1470-nm group (p = 0.004). The median VCSS decreased from 4 to 2 in the 980-nm group (p < 0.001) and from 8 to 2 (p < 0.001) in the 1470-nm group. At 1-year follow-up, seven veins treated with 980 nm and two veins treated with 1470 nm were recanalized (p = 0.16); the average linear endovenous energy density (LEED) was 83.9 (r, 55-100) J/cm and 58.5 (r, 45-115) J/cm, respectively (p < 0.001). Postoperative minor complications occurred in 23 (29.4 %) limbs in the 980-nm group and in 19 (25.6 %) limbs of the 1470-nm group (p = 0.73). EVLA with the 1470-nm laser have less energy deposition for occlusion and better treatment response. PMID:25990260

  5. Elimination of photon quenching by a transition layer to fabricate a quenching-shield sandwich structure for 800 nm excited upconversion luminescence of Nd3+-sensitized nanoparticles.

    PubMed

    Zhong, Yeteng; Tian, Gan; Gu, Zhanjun; Yang, Yijun; Gu, Lin; Zhao, Yuliang; Ma, Ying; Yao, Jiannian

    2014-05-01

    Nd3+-sensitized quenching-shield sandwich-structured upconversion nanoparticles are reported, which exhibit highly efficient upconversion photoluminescence under excitation by an 800 nm continuous-wave laser. The transition-layer structure is essential to bridge energy transfer from the sensitizer to the activator and simultaneously block energy back-transfer from the activator to the sensitizer. These 800 nm-excited upconversion nanoparticles are a key step toward the development of upconversion nanophosphors for biological applications. PMID:24338994

  6. 11 W single gain-chip dilute nitride disk laser emitting around 1180 nm.

    PubMed

    Korpijärvi, Ville-Markus; Leinonen, Tomi; Puustinen, Janne; Härkönen, Antti; Guina, Mircea D

    2010-12-01

    We report power scaling experiments of a GaInNAs/GaAs-based semiconductor disk laser operating at ~1180 nm. Using a single gain chip cooled to mount temperature of ~10 °C we obtained 11 W of output power. For efficient thermal management we used a water-cooled microchannel mount and an intracavity diamond heat spreader. Laser performance was studied using different spot sizes of the pump beam on the gain chip and different output couplers. Intracavity frequency-doubling experiments led to generation of ~6.2 W of laser radiation at ~590 nm, a wavelength relevant for the development of sodium laser guide stars. PMID:21164909

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

    PubMed

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

    2013-09-01

    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. PMID:24104041

  8. High power frequency doubled GaInNAs semiconductor disk laser emitting at 615 nm.

    PubMed

    Härkönen, Antti; Rautiainen, Jussi; Guina, Mircea; Konttinen, Janne; Tuomisto, Pietari; Orsila, Lasse; Pessa, Markus; Okhotnikov, Oleg G

    2007-03-19

    We report on an optically-pumped intracavity frequency doubled GaInNAs/GaAs -based semiconductor disk laser emitting around 615 nm. The laser operates at fundamental wavelength of 1230 nm and incorporates a BBO crystal for light conversion to the red wavelength. Maximum output power of 172 mW at 615 nm was achieved from a single output. Combined power from two outputs was 320 mW. The wavelength of visible emission could be tuned by 4.5 nm using a thin glass etalon inside the cavity. PMID:19532562

  9. 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%. PMID:27464139

  10. Dual-wavelength laser operation at 1061 and 942 nm in Nd:GSAG

    NASA Astrophysics Data System (ADS)

    Fu, X. H.; Che, Y.; Li, Y. L.

    2011-06-01

    A dual-wavelength continuous-wave (CW) diode end-pumped gadolinium scandium aluminum garnet (Nd:GSAG) laser that generates simultaneous laser action at the wavelengths 1061 and 942 nm is demonstrated. A total output power of 589 mW (476 mW at 1061 nm and 113 mW at 942 nm) for the dual-wave-length was achieved at the incident pump power of 18.2 W. The M 2 values for 942 and 1061 nm lights were found to be around 1.18 and 1.37, respectively.

  11. 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).

  12. 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).

  13. Efficient continuous-wave intracavity frequency-doubled Nd:YAG-LBO blue laser at 473 nm under diode pumping directly into the emitting level

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Yin, X. D.; Xia, J.; Wang, R. G.; Wang, D.

    2010-01-01

    We report the efficient blue laser at 473 nm generation by intracavity frequency doubling of a continuous wave laser operation of a 885 nm diode direct pumped Nd:YAG laser on the 4F3/2 → 4I9/2 transition at 946 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 the absorbed pump power of 18.7 W, as high as 4.3 W of continuous wave output power at 473 nm is achieved with 15 mm long LBO. The optical-to-optical conversion efficiency with respect to the absorbed power is up to 0.23, and the beam quality M2 value is 1.2.

  14. 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.

  15. 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.

  16. 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. PMID:23464682

  17. 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

  18. Watt-level continuous-wave diode lasers at 1180 nm with high spectral brightness

    NASA Astrophysics Data System (ADS)

    Paschke, K.; Blume, G.; Brox, O.; Bugge, F.; Fricke, J.; Feise, D.; Hofmann, J.; Wenzel, H.; Erbert, G.

    2015-03-01

    Distributed Bragg reflector (DBR) tapered lasers emitting near 1180 nm were developed. The integration of DBR surface gratings in an edge-emitting laser structure with a highly strained quantum well and a tapered laser geometry allows nearly diffraction limited emission into a single longitudinal mode with an optical output power of more than 2 W. The laser will allow direct second harmonic generation (SHG) in a single pass configuration and hence will enable the manufacturing of miniaturized laser modules near 590 nm for out-of-the-lab applications. An integration of a heater element at the DBR grating allows the tuning of the emission wavelength of more than 2 nm without the mechanical movement of gratings. This easy tuning simplifies the phase matching to a SHG crystal.

  19. 1120nm highly brilliant laser sources for SHG-modules in bio-analytics and spectroscopy

    NASA Astrophysics Data System (ADS)

    Paschke, Katrin; Fiebig, Christian; Blume, Gunnar; Bugge, Frank; Fricke, Jörg; Erbert, Götz

    2013-03-01

    Highly brilliant diode lasers at 1120nm with a high optical output power, nearly diffraction limited beam and narrow spectral line width are increasingly important for non-linear frequency conversion to 560 nm. We present experimental results about edge-emitting distributed Bragg reflector (DBR) tapered diode lasers emitting at 1120 nm. The investigated lasers show an output power of up to 8W with a conversion efficiency of about 40%, and a lifetime of more than 5000 h at 5 W. The lasers also exhibit a small vertical divergence <15° full width at half maximum (FWHM), a nearly diffraction limited beam quality, and a narrow spectral line width with FWHM smaller than 10pm. These properties allow the lasers to be used for future second harmonic (SH) generation.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  3. 1579 NM Fiber Laser Source for Spaceborne Monitoring of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Cézard, Nicolas; Lombard, Laurent; Le Gouët, Julien; Goular, Didier; Bresson, Alexandre; Dolfi-Bouteyre, Agnès; Canat, Guillaume

    2016-06-01

    We report on the development of a 1579 nm pulsed fiber laser source with high peak-power, intended to be used as a lidar source for CO2 monitoring from space. We first discuss water-vapor sensitivity of spaceborne CO2 measurements by lidar and point the interest of the 1579 nm wavelength with that respect. Then we detail the current development status of the pulsed fiber laser source.

  4. 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%. PMID:26393759

  5. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat.

    PubMed

    Li, Rui; Slipchenko, Mikhail N; Wang, Pu; Cheng, Ji-Xin

    2013-04-01

    Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C-H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated. PMID:23536057

  6. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat

    PubMed Central

    Li, Rui; Slipchenko, Mikhail N.; Wang, Pu

    2013-01-01

    Abstract. Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C–H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated. PMID:23536057

  7. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat

    NASA Astrophysics Data System (ADS)

    Li, Rui; Slipchenko, Mikhail N.; Wang, Pu; Cheng, Ji-Xin

    2013-04-01

    Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C-H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated.

  8. 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. PMID:27557253

  9. 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.

  10. 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.

  11. Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta.

    PubMed

    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

    2015-09-01

    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 Ca(2+) 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

  12. 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

  13. Compact non-cascaded all-fiber Raman laser operating at 1174 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jiachen; Lee, Sang Bae; Lee, Kwanil

    2016-07-01

    We investigate a non-cascaded, all-fiber, single-mode Raman fiber laser (RFL) operating at 1174 nm with an optical slope efficiency of 68%. An ~1-km commercial single-mode fiber is used as the Raman gain medium. The RFL cavity is formed between a high reflectivity fiber Bragg grating (FBG) and a perpendicularly-cleaved fiber facet. The laser is pumped by using a homemade ytterbium-doped fiber laser (YDFL) and can be frequency doubled to generate yellow light. Under the optimum condition, A 6.9-W 1174-nm laser is obtained at maximum available power (24 W) of a laser diode pump. The optical conversion efficiency and the net slope efficiency of the RFL were respectively, 29% and 38%, with respect to launched diode laser power. We also demonstrate yellow-light generation by frequency doubling of the RFL.

  14. 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.

  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. Mask inspection microscopy with 13.2 nm table-top laser illumination

    SciTech Connect

    Brizuela, Fernando; Wang, Yong; Brewer, Courtney A.; Pedaci, Francesco; Chao, Weilun; Anderson, Erik H.; Liu, Yanwei; Goldberg, Kenneth A.; Naulleau, Patrick; Wachulak, Przemyslaw; Marconi, Mario C.; Attwood, David T.; Rocca, Jorge J.; Menoni, Carmen S.

    2008-10-14

    We report the demonstration of a reflection microscope that operates at 13.2-nm wavelength with a spatial resolution of 55 {+-} 3 nm. The microscope uses illumination from a table-top EUV laser to acquire aerial images of photolithography masks with a 20 second exposure time. The modulation transfer function of the optical system was characterized.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  18. 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.

  19. 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.

  20. 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

  1. 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)

  2. Formation of Micro and Nano Structures Using VUV 157 nm Laser Radiation

    SciTech Connect

    Walton, C. D.; Cockcroft, S.

    2010-10-08

    We report on laser ablation experiments on micro and nano size composite structures. The surface of CR-39 and polycarbonate has been intentionally seeded with silicon carbide and silver nanowires and subsequently laser irradiated at a wavelength of 157 nm. We show scanning electron micrograph images of prismatic and conical structures produced by laser ablation and discuss a shape transformation from a prismatic to a conical structure.

  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. High-Efficiency 800 nm Multi-Layer Dielectric Gratings for High Average Power Laser Systems

    SciTech Connect

    Nguyen, H T; Britten, J A; Patel, D; Brizuela, F; Rocca, J J; Menoni, C S

    2006-06-15

    We report on the design, fabrication, and performance of a 1740 l/mm multilayer dielectric diffraction grating for use with 800 nm light. At an input angle of 8{sup o} from Littrow and a wavelength from 770 to 830 nm, >90% diffraction efficiency is achieved, with peak diffraction efficiency of >97% at 800nm. We will also comment on laser damage threshold and power-handling properties.

  5. High-power 467-nm passively locked signal-resonant sum-frequency laser

    SciTech Connect

    Wigley, P.G.; Zhang, Q.; Miesak, E.; Dixon, G.J.

    1995-12-01

    We have generated more than 120 mW of TEM{sub 00} radiation at 467 nm by summing the resonantly enhanced output of an 845-nm GaAlAs tapered semiconductor amplifier with the intracavity field of a 1047-nm diode-pumped Nd:YLF laser, using a KTP crystal. Optical feedback was used to lock the frequency of the tapered amplifier to a cavity resonance. {copyright} {ital 1995 Optical Society of America.}

  6. 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.

  7. Efficient diode double-end-pumped Nd:YVO4 laser operating at 1342nm.

    PubMed

    Ogilvy, Hamish; Withford, Michael; Dekker, Peter; Piper, James

    2003-09-22

    A Nd:YVO4 laser producing over 8W cw TEM00 at 1342nm with slope efficiency of 42% and optical to optical conversion efficiency of 33% has been demonstrated. Low neodymium doping concentration helps to reduce thermal loading in the laser crystal and increase achievable output power. While single end pumping approaches the crystal fracture limit, double-end-pumping effectively divides the thermal loading between the two ends of the laser crystal, allowing for reduced risk of fracture and greater power-scalability. Intracavity frequency doubling in LBO generated cw output powers over 900mW at 671nm. PMID:19471351

  8. 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

  9. 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.

  10. 219.3 W CW diode-side-pumped 1123 nm Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Bo, Y.; Xu, Y. T.; Yang, F.; Wang, Z. C.; Wang, B. S.; Xu, J. L.; Gao, H. W.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2010-07-01

    We demonstrate a high power continuous wave (CW) diode-side-pumped Nd:YAG laser operating at 1123 nm with a plano-plano configuration. By means of precise coating, a single 1123 nm wavelength is achieved. Under the pump power of 1080 W, an output power of 219.3 W is obtained, which corresponds to an optical-optical conversion efficiency of 20.3%. To the best of our knowledge, this is the highest output power for CW 1123 nm laser based on Nd:YAG crystal.

  11. 93.7 W 1112 nm diode-side-pumped CW Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Wang, Z. C.; Xu, Y. T.; Yang, F.; Wang, B. S.; Gao, H. W.; Bo, Y.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2010-07-01

    We demonstrate a high power continuous wave (CW) infrared laser operated at 1112 nm from a diode side-pumped Nd:YAG crystal with a plano-plano symmetrical resonator. By inserting an etalon, an output power of as high as 93.7 W at 1112 nm was obtained at the pump power of 570 W with conversion efficiency of 16.4%. The beam quality factor of M2 was measured to be about 17. The wavelength tunable performance of the etalon was also analyzed. To the best of our knowledge, it is the highest output power at 1112 nm CW laser based on Nd:YAG crystal.

  12. An all-solid-state laser source at 671 nm for cold-atom experiments with lithium

    NASA Astrophysics Data System (ADS)

    Eismann, U.; Gerbier, F.; Canalias, C.; Zukauskas, A.; Trénec, G.; Vigué, J.; Chevy, F.; Salomon, C.

    2012-01-01

    We present an all-solid-state narrow-linewidth laser source emitting 670 mW output power at 671 nm delivered in a diffraction-limited beam. The source is based on a frequency-doubled diode-end-pumped ring laser operating on the 4 F 3/2→4 I 13/2 transition in Nd:YVO4. By using periodically poled potassium titanyl phosphate (ppKTP) in an external buildup cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over 100 GHz is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally, a simplified design based on intra-cavity doubling is described and first results are presented.

  13. Saturated amplification of a collisionally pumped optical-field-ionization soft X-ray laser at 41.8 nm.

    PubMed

    Sebban, S; Haroutunian, R; Balcou, P; Grillon, G; Rousse, A; Kazamias, S; Marin, T; Rousseau, J P; Notebaert, L; Pittman, M; Chambaret, J P; Antonetti, A; Hulin, D; Ros, D; Klisnick, A; Carillon, A; Jaeglé, P; Jamelot, G; Wyart, J F

    2001-04-01

    We report the first saturated amplification of an optical-field-ionization soft x-ray laser. The amplifying medium is generated by focusing a circularly polarized 330-mJ, 35-fs, 10-Hz Ti:sapphire laser system in a few-mm cell filled with xenon. A gain of 67 cm(-1) on the 4d(9)5p-4d(9)5d transition at 41.8 nm in Pd-like xenon and a gain-length product of 15 have been inferred at saturation. This source delivers about 5 x 10(9) photons per pulse. The influence of the pumping energy and the laser polarization on the lasing output are also presented. PMID:11290093

  14. ED50 determination of corneal lesions produced by 1318-nm laser radiation pulses

    NASA Astrophysics Data System (ADS)

    Ketzenberger, Bryan K.; Johnson, Thomas E.; Wild, Steven P.; Pletcher, Kenneth B.; Roach, William P.

    2001-05-01

    High-energy use of 1318 nm laser systems is becoming more prevalent in military and industrial settings. Threshold, ED50, exposure data and mechanism of laser-tissue interaction need to be determined for this wavelength using appropriate animal models that allow for extrapolation to control human exposures. Threshold, ED50, exposure data at 1318 nm for retinal and corneal injury have previously been undertaken and reported for rhesus monkeys. Using comparable methods, we examine exposure data at 1318 nm to determine the ED50 and laser-tissue interaction in the rabbit model to evaluate cornea. We present preliminary data for the ED50 threshold on the cornea from exposure to 1318 nm single laser pulses. Delivery of laser energy is accomplished using an Nd:YAG system producing 1318 nm light in the 0.5 millisecond time exposure regime and in the range of 0 to 500 mJ. Results from this work will aid in the establishment of safety standards for near infrared laser systems.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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. PMID:26406520

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

    Saydjari, Yves; 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

  6. Non inverted gain lineshapes of the cesium resonance transition at 894 nm

    NASA Astrophysics Data System (ADS)

    Cataliotti, F. S.; Fort, C.; Prevedelli, M.; Hänsch, T. W.; Inguscio, M.

    1997-01-01

    We report on electromagnetically induced transparency (EIT) in a V-type system in cesium. We investigated the induced EIT as a function of the pump-laser power for different hyperfine components on the D1-D2 lines. Adding repumping light on the D1 transition we observed 2% single pass gain.

  7. 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.

  8. 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.

  9. Single-frequency fiber laser at 1950 nm based on thulium-doped silica fiber.

    PubMed

    Fu, Shijie; Shi, Wei; Lin, Jichao; Fang, Qiang; Sheng, Quan; Zhang, Haiwei; Wen, Jinwei; Yao, Jianquan

    2015-11-15

    A single-frequency fiber laser operating at 1950 nm has been demonstrated in an all-fiber distributed Bragg reflection laser cavity by using a 1.9 cm commercially available thulium-doped silica fiber, for the first time, to the best of our knowledge. The laser was pumped by a 793 nm single-mode diode laser and had a threshold pump power of 75 mW. The maximum output power of the single longitudinal mode laser was 18 mW and the slope efficiency with respect to the launched pump power was 11%. Moreover, the linewidth and relative intensity noise at different pump power have been measured and analyzed. PMID:26565855

  10. 976 nm single-frequency distributed Bragg reflector fiber laser.

    PubMed

    Zhu, Xiushan; Shi, Wei; Zong, Jie; Nguyen, Dan; Norwood, Robert A; Chavez-Pirson, Arturo; Peyghambarian, N

    2012-10-15

    A single-frequency distributed Bragg reflector (DBR) fiber laser at 976 nm was developed with a 2 cm long highly ytterbium-doped phosphate fiber and a pair of silica fiber Bragg gratings. More than 100 mW of linearly polarized output was achieved from the all-fiber DBR laser with a linewidth less than 3 kHz. The outstanding features of this single-frequency laser also include ultralow relative intensity noise and high wavelength stability. This fiber laser is an excellent seeder for high-power 976 nm narrow-linewidth laser amplifiers that can be used for efficient coherent blue-light generation through frequency doubling. PMID:23073399

  11. 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. PMID:27250390

  12. 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.

  13. Aesthetic earlobe remodeling: my personal experience with an LBO laser at 532 nm.

    PubMed

    Scrimali, Luca; Tamburino, Serena

    2014-06-01

    Since 1960, when Maiman built the first laser equipment, this technology has gone through a continuous development and an increasing utilization in several fields. Nowadays many pathologies find a less traumatic solution in laser technology. Laser can be either used to treat lesions with a high bleeding risk such as hemangioma and lymphangioma or in patients with coagulation diseases or hypertension, taking advantage of its capability to coagulate. Moreover healing and scarring are improved by the laser's effect of biostimulation and inhibition of bacterial growth, this leading to a greater comfort for the patient. The tissue vaporization and the dimension of the damaged area depend on several factors, those related to the laser used, such as wavelength, power, emission mode (continued or pulsed mode) and the power density, and those concerning to the treated tissue, like color and consistency. In this Study, we used an Lithium Borate, (LBO), laser, instead of scalpel for earlobe reduction in a 35-year-old male patient with pending lobule. LBO laser works through a solid active medium emitting a visible green light. A diode laser, with a wavelength of 810 nm, stimulates a crystal of Nd:YAG, which has a wavelength of 1064 nm. Then a crystal of LBO doubles the vibration frequency of the photons, leading to a final wavelength of 532 nm. PMID:24802299

  14. All-solid-state dual end pumped Nd:YAG/LBO yellow green laser with 10.8 W output power at 561 nm

    NASA Astrophysics Data System (ADS)

    Zhu, P. F.; Zhang, C. M.; Song, P.; Bai, L.; Yao, Y.

    2015-04-01

    It is reported that the efficient and compact yellow green laser at 561 nm generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:YAG laser on the 4 F 3/2 → 4 F 13/2 transition operated at 1123 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. With dual end pump configurations at total incident pump power of 40 W, as high as 10.8 W of CW output power at 561 nm is achieved with 20 mm long LBO. The optical-to-optical conversion efficiency is up to 27%, and the power stability in 8 h is better than 2.56%.

  15. All-solid-state dual end pumped YVO4:Nd/LBO blue laser with 21.8 W output power at 457 nm

    NASA Astrophysics Data System (ADS)

    Ling, Zhao; Yi, Yao; Yang, Zhao; Quan, Zheng

    2014-03-01

    It is reported the efficient compact deep-blue laser at 457 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode-pumped YVO4:Nd laser on the 4 F 3/2 → 4 I 9/2 transition at 914 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. With dual end pump configurations at total incident pump power of 60 W, as high as 21.8 W of CW output power at 457 nm is achieved with 20-mm-long LBO. The optical-to-optical conversion efficiency is up to 36.3%, and the power stability in 8 h is better than 2.36%.

  16. Frequency doubled pulsed single longitudinal mode Nd:YAG laser at 1319 nm with pulse build-up negative feedback controls

    NASA Astrophysics Data System (ADS)

    Bakanas, Ramunas; Pileckas, Julius

    2010-02-01

    We report on creation of frequency doubled E-O Q-switched Nd:YAG laser lasing Single Longitudinal and Transversal mode radiation at 1319 nm (4F3/2 to 4I11/2 transition) at repetition rate of 10 Hz. By means of linear resonator stable redlight pulses were obtained at 660 nm having Emax = 5mJ output energy and τ = 50 ns (FWHM) pulse duration by using NCPM LBO crystal as an extra-cavity frequency doubler. Laser design incorporates particularly made fast negative feedback loop controls for pulse buildup control. It allowed obtaining much more stable laser performance as well as much shorter Optical Jitter and fast pulse buildup time. To best our knowledge, these are the first time such pulse energy, rep rate Transversal and Longitudinal mode structure ever achieved in compact flashlamp pumped E-O Q-Switched laser operating at 1319 nm.

  17. 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.}

  18. 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. PMID:22229689

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  1. Bidirectional laser triggering in highly-resistive vanadium-dioxide thin films by using a 966-nm pump laser diode

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Kim, Bong-Jun; Yu, Bong-Ahn; Kang, Hyun Wook; Nam, Seung Yun; Oh, Junghwan; Lee, Yong Wook

    2016-01-01

    By incorporating a 966-nm pump laser diode, we realized bidirectional laser triggering in a twoterminal planar device based on a highly-resistive vanadium-dioxide (VO2) thin film grown by using the pulsed laser deposition method. Bidirectional laser triggering of up to 10 mA was achieved by directly illuminating the VO2 film with a focused infrared laser beam, and the transient responses of the laser-triggered currents were analyzed. A switching contrast between the off-state and the on-state currents was measured as ˜3571, and the rising and the falling times were measured as ˜40 and ˜20 ms, respectively, when laser pulses with a pulse width of 100 ms excited the VO2-based device.

  2. Continuous-wave, single-frequency 229  nm laser source for laser cooling of cadmium atoms.

    PubMed

    Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi

    2016-02-15

    Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks. PMID:26872168

  3. 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.

  4. Self-Q-switched Cr:LiCAF laser near 800 nm

    NASA Astrophysics Data System (ADS)

    Beyatli, Ersen; Sennaroglu, Alphan; Demirbas, Umit

    2013-03-01

    Self-Q-switching (SQS) of lasers enable the generation of Q-switched pulses from simple laser cavities without using any additional saturable absorbers or active modulators. Earlier studies have reported SQS in ruby, Nd:YAG, and Cr:LiSAF lasers. However, these systems were mostly flashlamp pumped and required cooling of the crystal and/or misalignment of the laser cavity for the observation of SQS. In this presentation, for the first time to our knowledge, we report SQS operation of a Cr:LiCAF laser. SQS was achieved in an astigmatically compensated x-cavity containing only a Cr:LiCAF crystal that was end-pumped with a 140-mW continuous-wave (cw) diode at 660 nm. During regular cw operation, the laser produced a diffraction-limited beam with 50 mW of output power and had a spectral width of 0.5 nm near 795 nm. SQS operation of the Cr:LiCAF laser could be initiated by fine adjustment of the separation between the curved mirrors of the cavity and was observed at several mirror separations within the stability range of the resonator. During SQS operation, the laser generated saw-tooth-shaped pulses with 20-30 microsecond duration in the 780-800 nm wavelength range, at repetition rates between 10 and 30 kHz. SQS operation was further accompanied with a decrease in the output power to the 30-45 mW range. In this regime, the output beam became multimode and spectral broadening up to 12.5 nm (FWHM) was observed.

  5. Absolute frequency measurement of the ^1S0<->^3P0 clock transition at 578.4 nm in ytterbium

    NASA Astrophysics Data System (ADS)

    Hoyt, Chad; Barber, Zeb; Oates, Chris; Fortier, Tara; Diddams, Scott

    2005-05-01

    We report the first precision absolute frequency measurements of the highly forbidden (6s^2)^1S0<->(6s6p)^3P0 optical clock transition at 578.4 nm in two odd isotopes of ytterbium. Atoms are cooled to tens of microkelvins in two successive stages of laser cooling and magneto-optical trapping that use transitions at 398.9 nm and 555.8 nm, respectively. The resulting trapped atomic cloud is irradiated with excitation light at 578.4 nm and absorption is detected by monitoring trapped atom depletion. With the laser on resonance, we demonstrate trap depletions of more than 80 % relative to the off-resonance case. Absolute frequency measurements are made for ^171Yb (I=1/2) and ^173Yb (I=5/2) with an uncertainty of 4.4 kHz using a femtosecond-laser frequency comb calibrated by the NIST cesium fountain clock. The natural linewidth of these J=0 to J=0 transitions is ˜10 mHz, making them well-suited to support a new generation of optical atomic clocks based on confinement in an optical lattice. Lattice-based optical clocks have the potential to surpass the performance of the best current atomic clocks by orders of magnitude. The accurate ytterbium frequency knowledge presented here (nearly a million-fold reduction in uncertainty) will greatly expedite Doppler- and recoil-free lattice spectroscopy.

  6. Single-frequency ytterbium-doped fiber laser at 976 nm

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Shi, W.; Zong, J.; Nguyen, D.; Norwood, R. A.; Chavez-Pirson, A.; Peyghambarian, N.

    2013-02-01

    Linearly polarized wavelength stable single frequency ytterbium (Yb3+) doped fiber lasers below 1 μm, namely threelevel Yb3+ fiber lasers, are highly demanded for nonlinear wavelength conversion to generate coherent blue light or even deep ultraviolet coherent sources. We present performance of a 976 nm single-frequency core-pumped distributed Bragg reflector (DBR) fiber laser consisting of a 2-cm long highly ytterbium-doped phosphate fiber and a pair of silica fiber Bragg gratings (FBGs) and their use for frequency doubling experiment. The high reflection (HR > 99%) and partial reflection (PR = 60%) FBGs were cleaved very close to the index modulation region and directly spliced to a 2-cm-long highly Yb3+-doped phosphate fiber. Over 100 mW of linearly polarized output with a linewidth less than 2 kHz can be obtained when the launched pump power is about 450 mW. The efficiency of the 976 nm single-frequency fiber laser (the output power vs the launched pump power) is about 25%. The relative intensity noise was measured to be -110 dB/Hz at 1 MHz and the variation of the center wavelength is less than 0.0005 nm during a measurement period of 2.5 hours. This single-frequency fiber laser has an SNR of over 50 dB and there is no strong ASE or spurious lasing at long wavelengths even at the maximum pump power. This all-fiber single-frequency DBR laser with attractive features can be used for efficient blue and UV generation through nonlinear frequency conversion. Moreover, this high-performance 976 nm single-frequency fiber laser can be used as a single-frequency, low RIN pump laser for long wavelength Yb3+-, Er3+-, or Yb3+/Er3+-doped fiber lasers and amplifiers.

  7. 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.

  8. 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.

  9. Plasmonic effects on the laser-induced metal-insulator transition of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Ferrara, Davon W.; MacQuarrie, Evan R.; Nag, Joyeeta; Haglund, Richard F., Jr.

    2010-03-01

    Vanadium dioxide (VO2) is a strongly-correlated electron material with a well-known semiconducting to metallic phase transition that can be induced thermally, optically, or electrically. When switched to the high-temperature (T > 68°C) metallic phase, the greatest contrast in the optical properties occurs at wavelengths in the near-to-mid-infrared and beyond. In the visible to near-infrared, however, upon switching for wavelengths between ~500-1000 nm, VO2 transmits more light in the metallic phase. In this paper, we report studies of the effect of near-IR irradiation (785 nm) on lithographically prepared arrays of gold nanoparticles (NPs) covered with a thin film of VO2 and find that the presence of the NPs substantially lowers the laser threshold for low-power induction of the phase transition. Hybrid Au::VO2 structures were created by coating lithographically prepared arrays of gold nanoparticles (NPs) (diameters 140 and 200 nm, array spacing 450 nm) with 60 nm thick films of VO2 by pulsed laser deposition. Due to resonant absorption of the Au particle-plasmon resonance (PPR) at 785 nm, a temperature-dependent shift in the PPR can be generated by switching the VO2 from one phase to another. We have measured the switching behavior of VO2 and Au::VO2 structures using shuttered CW laser irradiation in order to study both optical and thermal mechanisms of the phase transition. Transient absorption measurements using a shuttered 785 nm pump laser corresponding to the PPR resonance of the Au NPs and 1550 nm CW probe show that the presence of the Au NPs lowers the threshold laser power required to induce the phase transition.

  10. 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.

  11. Highly efficient ytterbium-doped phosphosilicate fiber lasers operating below 1020 nm.

    PubMed

    Gu, Guancheng; Liu, Zhengyong; Kong, Fanting; Tam, Hwayaw; Shori, Ramesh K; Dong, Liang

    2015-07-13

    Highly-efficient high-power fiber lasers operating at wavelength below 1020 nm are critical for tandem-pumping in >10 kW fiber lasers to provide high pump brightness and low thermal loading. Using an ytterbium-doped-phosphosilicate double-clad leakage-channel fiber with ~50 µm core and ~420 µm cladding, we have achieved ~70% optical-to-optical efficiency at 1018 nm. The much larger cladding than those in previous reports demonstrates the much lower required pump brightness, a key for efficient kW operation. The demonstrated 1018 nm fiber laser has ASE suppression of ~41 dB. This is higher than previous reports and further demonstrates the advantages of the fiber used. Limiting factors to efficiency are also systematically studied. PMID:26191831

  12. Single mode 1018nm fiber laser with power of 230W

    NASA Astrophysics Data System (ADS)

    Glick, Yaakov; Sintov, Yoav; Zuitlin, Roey; Pearl, Shaul; Feldman, Revital; Horvitz, Zvi; Shafir, Noam

    2016-03-01

    We have developed a high power single-mode (SM) monolithic fiber laser at 1018 nm, producing 230 W CW, with an M2 of 1.17 and light to light efficiency of 75%. To the best of our knowledge this is the highest power described in the open literature from a SM fiber laser at this wavelength. Careful simulations were employed which take into account the various wavelength dependent parameters such as the fiber absorption and emission as obtained from the fiber manufacturers, and the cavity mirrors' reflection, in addition to the fiber geometrical parameters. It was found that the major obstacle for increasing the power at 1018nm is the self-generation of amplified spontaneous emission at wavelengths of 1030-1040nm. If the laser is not designed properly these undesired wavelengths dominate the output spectrum.

  13. 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.

  14. 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.

  15. The direct measurement of ablation pressure driven by 351-nm laser radiation

    NASA Astrophysics Data System (ADS)

    Fratanduono, D. E.; Boehly, T. R.; Celliers, P. M.; Barrios, M. A.; Eggert, J. H.; Smith, R. F.; Hicks, D. G.; Collins, G. W.; Meyerhofer, D. D.

    2011-10-01

    The instantaneous scaling of ablation pressure to laser intensity is directly inferred for ramp compression of diamond targets irradiated by 351-nm light. Continuously increasing pressure profiles from 100 to 970 GPa are produced by direct-drive laser ablation at intensities up to 7 × 1013 W/cm2. The free-surface velocity on the rear of the target is used to directly infer the instantaneous ablation-pressure profile at the front of the target. The laser intensity on target is determined by laser power measurements and fully characterized laser spots. The ablation pressure is found to depend on the laser intensity as P(GPa )=42(±3)[I(TW/cm2)]0.71(±0.01).

  16. Single-frequency linearly-polarized 1083 nm all fiber nanosecond laser

    NASA Astrophysics Data System (ADS)

    Su, Rongtao; Xu, Jiangmin; Zhou, Pu; Ji, Xiang; Xu, Xiaojun

    2012-12-01

    Single-frequency linearly-polarized 1083 nm all fiber nanosecond master-oscillator power amplifier laser system is demonstrated. A ring laser, whose key components are one saturable absorber and two polarization controllers, delivers a single-frequency continuous wave laser. Using an electro-optic modulator as the modulator, the pulse laser seed is obtained by modulating the CW laser. By amplifying the pulse seed to the average power of 61.6 W in three stages, a single-frequency linearly-polarized laser with pulse duration of 16 ns, repetition rate of 10 MHz and pulse energy of 6.16 μJ is obtained. No nonlinear effect is observed in our experiment. Higher output power can be obtained by increasing LDs of the main amplifier.

  17. Singly resonant sum-frequency generation of 520-nm laser via a variable input-coupling transmission cavity

    NASA Astrophysics Data System (ADS)

    Guo, Shanlong; Ge, Yulong; He, Jun; Wang, Junmin

    2015-11-01

    We experimentally present a three-mirror folded singly resonant sum-frequency generation (SFG) cavity with an adjustable input coupling, which has been applied to 520-nm single-frequency laser generation via 780-nm laser and 1560-nm laser frequency mixing in a periodically poled KTiOPO4 crystal (PPKTP). A continuous variation in the input coupling reflectivity from 81.4 to 96.1% for 780-nm resonant laser is achieved by tilting the input coupler, and the impedance matching of the resonator can be optimized. Up to 268 mW of SFG output power at 520-nm is obtained with 6.8 W of the 1560-nm laser input and 1.5 W of 780-nm laser input.

  18. 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.

  19. 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.

  20. 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.

  1. Charge state dynamics of the nitrogen vacancy center in diamond under 1064-nm laser excitation

    NASA Astrophysics Data System (ADS)

    Ji, Peng; Dutt, M. V. Gurudev

    2016-07-01

    The photophysics and charge state dynamics of the nitrogen vacancy (NV) center in diamond has been extensively investigated, but is still not fully understood. In contrast to previous work, we find that NV0 converts to NV- under excitation with low power near-infrared (1064-nm) light, resulting in increased photoluminescence from the NV- state. We used a combination of spectral and time-resolved photoluminescence experiments and rate-equation modeling to conclude that NV0 converts to NV- via absorption of 1064-nm photons from the valence band of diamond. We report fast quenching and recovery of the photoluminescence from both charge states of the NV center under low power 1064-nm laser excitation, which has not been previously observed. We also find, using optically detected magnetic resonance experiments, that the charge transfer process mediated by the 1064-nm laser is spin dependent.

  2. 157 nm F2-laser writing of silica optical waveguides in silicone rubber

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R.

    2005-10-01

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nmF2-laser radiation. The 2 mm thick silicone was exposed through a thin (˜0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 µm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of ˜6 dB/cm is reported at the 1550 nm wavelength.

  3. 157 nm F2-laser writing of silica optical waveguides in silicone rubber.

    PubMed

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R

    2005-10-15

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nm F2-laser radiation. The 2 mm thick silicone was exposed through a thin (approximately 0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 microm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of approximately 6 dB/cm is reported at the 1550 nm wavelength. PMID:16252756

  4. Thin-disk Raman laser operation of Yb:YVO4/YVO4 around 1120 nm

    NASA Astrophysics Data System (ADS)

    Yang, F. G.; Qiao, L.; Xia, Z. C.

    2015-12-01

    We present diode-pumped Yb:YVO4/YVO4 thin-disk Raman laser operation around 1120 nm. The thin-disk crystals, Yb:YVO4, and the Raman crystal, YVO4, are cut with 250 μm and 20 mm, respectively. In multimode configurations, up to 0.91 W of Raman laser output power and a maximum slope efficiency of 10% are demonstrated corresponding to a pump power of 10 W. A continuous wavelength tuning range of 54 nm from 1096 to 1150 nm with a maximum output power of 320 mW at 1126 nm is confirmed.

  5. Thermal lensing in Nd:YVO4 laser with in-band pumping at 914 nm

    NASA Astrophysics Data System (ADS)

    Waritanant, Tanant; Major, Arkady

    2016-05-01

    Thermal lensing in an Nd:YVO4 laser system operating at 1064 nm with in-band pumping at 914 nm was characterized. The focal length of the thermal lens in the crystal was calculated using ABCD matrix formalism from the experimental data of the output beam diameter measurements made at different output power levels. The determined focal lengths of thermal lens were as strong as 4.4 diopters at 3.5 W of output power. The experimental results agree well with the finite element analysis of the developed laser system. A numerical comparison of the thermal lensing effect with 914-, 888-, 880-nm pumping, and with a standard 808-nm pumping was also made, demonstrating effective reduction of thermal lensing up to 2.1 times.

  6. 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.

  7. Removal of brain tissue by 1940-nm Tm-Fiber laser

    NASA Astrophysics Data System (ADS)

    Tunç, Burcu; Gülsoy, Murat

    2011-03-01

    The aim of the study was to investigate the thermal effects of the 1940-nm Tm-fiber laser on the dead brain tissue. 4-5 mm coronal sections were taken from lamb brains. Tm-fiber laser was applied at the back (cortical) and below the cortex (subcortical) of these slices with 0.5 mm distance. At the beginning of the research in order to find appropriate laser parameter to be compared for 1940-nm Tm-fiber laser, the carbonization and coagulation times of the brain slices were recorded for each power value, both for cortical and subcortical tissue. The appropriate laser parameters for lamb brain tissue were selected according to this study. Lasers were applied in both continuous and pulsed modes. In continuous mode, doses were changed with fixed application time. In pulsed mode, doses were modified with the change in pulse width. The lesions were detected with microscope. The radius of ablation and coagulation for each laser application was recorded. By calculating ablation efficiency (100xablation/calculation radius) the aproppriate laser doses were determined for both cortical and subcortical tissue. The maximum ablation efficiency for cortical tissue in continuous mode was 200 mW and 600 mW and in pulsed mode was 600 mW and for subcortical tissue maximum ablation efficiency was found 600 mW in both continuous mode and pulsed mode.

  8. High power, 1060-nm diode laser with an asymmetric hetero-waveguide

    NASA Astrophysics Data System (ADS)

    Li, T.; Hao, E.; Zhang, Yu

    2015-07-01

    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.

  9. 840 mW continuous-wave Fe:ZnSe laser operating at 4140 nm.

    PubMed

    Evans, Jonathan W; Berry, Patrick A; Schepler, Kenneth L

    2012-12-01

    We report the demonstration of high-power (840 mW) continuous-wave laser oscillation from Fe2+ ions in zinc selenide. The output spectrum of the Fe:ZnSe laser had a line-center near 4140 nm with a linewidth of 80 nm. The beam quality was measured to be M2≤1.2 with a maximum slope efficiency of 47%. Small shifts observed in output wavelength with increased output power were attributed to thermal effects. No thermal roll-off of slope efficiency was observed at the maximum of output power. PMID:23330210

  10. 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.

  11. All solid-state sum-frequency generation of 1.12-W continuous-wave laser at 588 nm

    NASA Astrophysics Data System (ADS)

    Lu, Yanfei; Zhang, Xihe; Yao, Zhihai

    2007-06-01

    A new resonator design for doubly resonant continuous-wave (CW) intracavity sum-frequency mixing (SFM) is reported. 1.12 W of coherent radiation at 588 nm is generated by mixing 1062-nm Nd:GdVO4 laser and 1319-nm Nd:YAG laser. The optical-to-optical conversion efficiency is up to 3.7%.

  12. 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.

  13. Highly reliable 198-nm light source for semiconductor inspection based on dual fiber lasers

    NASA Astrophysics Data System (ADS)

    Imai, Shinichi; Matsuki, Kazuto; Kikuiri, Nobutaka; Takayama, Katsuhiko; Iwase, Osamu; Urata, Yoshiharu; Shinozaki, Tatsuya; Wada, Yoshio; Wada, Satoshi

    2010-02-01

    Highly reliable DUV light sources are required for semiconductor applications such as a photomask inspection. The mask inspection for the advanced devices requires the UV lightning wavelength beyond 200 nm. By use of dual fiber lasers as fundamental light sources and the multi-wavelength conversion we have constructed a light source of 198nm with more than 100 mW. The first laser is Yb doped fiber laser with the wavelength of 1064 nm; the second is Er doped fiber laser with 1560 nm. To obtain the robustness and to simplify the configuration, the fundamental lights are run in the pulsed operation and all wavelength conversions are made in single-pass scheme. The PRFs of more than 2 MHz are chosen as an alternative of a CW light source; such a high PRF light is equivalent to CW light for inspection cameras. The light source is operated described as follows. Automatic weekly maintenance within an hour is done if it is required; automatic monthly maintenance within 4 hours is done on fixed date per month; manufacturer's maintenance is done every 6 month. Now this 198 nm light sources are equipped in the leading edge photomask inspection machines.

  14. Continuous-wave single-frequency laser with dual wavelength at 1064 and 532 nm.

    PubMed

    Zhang, Chenwei; Lu, Huadong; Yin, Qiwei; Su, Jing

    2014-10-01

    A continuous-wave high-power single-frequency laser with dual-wavelength output at 1064 and 532 nm is presented. The dependencies of the output power on the transmission of the output coupler and the phase-matching temperature of the LiB(3)O(5) (LBO) crystal are studied. An output coupler with transmission of 19% is used, and the temperature of LBO is controlled to the optimal phase-matching temperature of 422 K; measured maximal output powers of 33.7 W at 1064 nm and of 1.13 W at 532 nm are obtained with optical-optical conversion efficiency of 45.6%. The laser can be single-frequency operated stably and mode-hop-free, and the measured frequency drift is less than 15 MHz in 1 min. The measured Mx2 and My2 for the 1064 nm laser are 1.06 and 1.09, respectively. The measured Mx2 and My2 for the 532 nm laser are 1.12 and 1.11, respectively. PMID:25322220

  15. Nematic polymer liquid-crystal wave plate for high-power lasers at 1054 nm

    SciTech Connect

    Kreuzer, F. ); Korenic, E.M.; Jacobs, S.D.; Houghton, J.K.; Schmid, A. )

    1994-04-01

    A nematic polymer liquid crystal is used to construct wave plates for use at 1054 nm. Three methods of wave-plate construction are discussed: double substrate with fiber spacers in homogeneous distribution, double substrate with fiber spacers in annular distribution, and single substrate. The polymer liquid crystal shows high laser-damage resistance, making it particularly useful for high-peak-power laser applications. Alignment techniques and measurement of birefringence for the highly viscous polymer are described.

  16. Optically pumped semiconductor quantum dot disk laser operating at 1180 nm.

    PubMed

    Rautiainen, Jussi; Krestnikov, Igor; Butkus, Mantas; Rafailov, Edik U; Okhotnikov, Oleg G

    2010-03-01

    We demonstrate an optically pumped semiconductor disk laser using 39 layers of Stranski-Krastanov InGaAs quantum dots self-assembled during epitaxial growth on a monolithic GaAs/AlAs distributed Bragg reflector. The gain structure bonded to an intracavity diamond crystal heat spreader allows 1.75 W single-transverse-mode output (M(2)<1.2) with circular beam shape operating at 1180 nm in a disk laser geometry. PMID:20195322

  17. 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.

  18. Double-end-pumped Nd:YVO4 slab laser at 1064 nm.

    PubMed

    Xu, Liu; Zhang, Hengli; He, Jingliang; Yu, Xilong; Cui, Li; Mao, Yefei; Sun, Xiao; Lin, Xin; Xing, Jichuan; Xin, Jianguo

    2012-04-20

    We demonstrate a high-power laser diode stacks double-end-pumped Nd:YVO4 1064 nm slab laser with a folded stable-unstable hybrid resonator. An output power of 220 W was obtained at the pump power of 490 W with optical conversion efficiency of 44.9%. At the output power of 202 W, the M2 factors in the unstable direction and in the stable direction were 1.7 and 2.3, respectively. PMID:22534909

  19. Holographic Generation Of Gratings With Periodicities Below 150 nm With An Excimer Laser

    NASA Astrophysics Data System (ADS)

    Ahlhorn, T.; Pohlmann, Hauke; Kotthaus, Jorg P.

    1989-04-01

    Holographic generation of gratings with periodicities down to 140nm in thin polymethyl methacrylate (PMMA) layers on Si-substrates using a narrow band KrF-excimer laser (λ=248 nm) is reported. At low single pulse energy densities (<3OmJ/cm2) the gratings are prepared by conventional photolithography. At higher single pulse energy densities (>70mJ/cm2) we directly write gratings in the PMMA by photoetching (ablation).

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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)

  8. 120 nm Bandwidth noise-like pulse generation in an erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Zhao, L. M.; Tang, D. Y.; Cheng, T. H.; Tam, H. Y.; Lu, C.

    2008-01-01

    We report on the generation of noise-like pulses with up to 120 nm bandwidth in a passively mode-locked erbium-doped fiber ring laser. By inserting a segment of slightly normal dispersion fiber in a mode-locked fiber laser cavity, we found that the spectrum of the noise-like pulse emission of the laser can be significantly broadened as a result of the four-wave-mixing and the soliton self-frequency shift effects in the inserted fiber.

  9. 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.

  10. 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

  11. 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.

  12. 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)

  13. Continuous-wave operation of a room-temperature, diode-laser-pumped, 946-nm Nd:YAG laser

    NASA Technical Reports Server (NTRS)

    Fan, T. Y.; Byer, Robert L.

    1987-01-01

    Single-stripe diode-laser-pumped operation of a continuous-wave 946-nm Nd:YAG laser with less than 10-mW threshold has been demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. KNbO3 and periodically poled LiNbO3 appear to be the most promising.

  14. Bidirectional current triggering in planar devices based on serially connected VO2 thin films using 965 nm laser diode.

    PubMed

    Kim, Jihoon; Park, Kyongsoo; Kim, Bong-Jun; Lee, Yong Wook

    2016-08-01

    By incorporating a 965 nm laser diode, the bidirectional current triggering of up to 30 mA was demonstrated in a two-terminal planar device based on serially connected vanadium dioxide (VO2) thin films grown by pulsed laser deposition. The bidirectional current triggering was realized by using the focused beams of laser pulses through the photo-thermally induced phase transition of VO2. The transient responses of laser-triggered currents were also investigated when laser pulses excited the device at a variety of pulse widths and repetition rates of up to 4.0 Hz. A switching contrast between off- and on-state currents was obtained as ~8333, and rising and falling times were measured as ~39 and ~29 ms, respectively, for 50 ms laser pulses. PMID:27505740

  15. 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. PMID:21499398

  16. 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

  17. 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. PMID:26625058

  18. 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)

  19. High Power Diode-End-Pumped Nd:YAG 946-nm Laser and Its Efficient Frequency Doubling

    NASA Astrophysics Data System (ADS)

    Zhou, Rui; Zhao, Shi-Yong; Cai, Zhi-Qiang; Zhang, Qiang; Wen, Wu-Qi; Ding, Xin; Wang, Peng; Ding, Li-Li; Yao, Jian-Quan

    2005-06-01

    We report a high power operation of the 4F3/2→4I9/2 transition in diode-end-pumped laser at 946 nm. The maximum output of 5.1 W is obtained with a short linear plano-concave cavity, and the slope efficiency is 24.5% at incident pump power of 23.3 W. To our knowledge, this is the highest value of the LD-pumped Nd:YAG 946 nm lasers that employ the conversional Nd:YAG rod as the gain medium. By intracavity frequency doubling with an LBO crystal, up to 982 mW cw output power in the blue spectral range at 473 nm is achieved at an incident pump power of 10.9 W with a compact three-element cavity, leading to optical-to-optical conversion efficiency of 9%. The conversion efficiency should be increased to 15.1%, if the rather low absorption coefficient of this Nd:YAG is considered.

  20. Template-induced structure transition in sub-10 nm self-assembling nanoparticles.

    PubMed

    Asbahi, Mohamed; Mehraeen, Shafigh; Lim, Kevin T P; Wang, Fuke; Cao, Jianshu; Tan, Mei Chee; Yang, Joel K W

    2014-05-14

    We report on the directed self-assembly of sub-10 nm gold nanoparticles confined within a template comprising channels of gradually varying widths. When the colloidal lattice parameter is mismatched with the channel width, the nanoparticles rearrange and break their natural close-packed ordering, transiting through a range of structural configurations according to the constraints imposed by the channel. While much work has been done in assembling ordered configurations, studies of the transition regime between ordered states have been limited to microparticles under applied compression. Here, with coordinated experiments and Monte Carlo simulations we show that particles transit through a more diverse set of self-assembled configurations than observed for compressed systems. The new insight from this work could lead to the control and design of complex self-assembled patterns other than periodic arrays of ordered particles. PMID:24702584

  1. 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%).

  2. 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. PMID:26796703

  3. Low-temperature high-density magneto-optical trapping of potassium using the open 4S{yields}5P transition at 405 nm

    SciTech Connect

    McKay, D. C.; Jervis, D.; Fine, D. J.; Simpson-Porco, J. W.; Edge, G. J. A.; Thywissen, J. H.

    2011-12-15

    We report the laser cooling and trapping of neutral potassium on an open transition. Fermionic {sup 40}K is captured using a magneto-optical trap (MOT) on the closed 4S{sub 1/2}{yields}4P{sub 3/2} transition at 767 nm and then transferred, with high efficiency, to a MOT on the open 4S{sub 1/2}{yields}5P{sub 3/2} transition at 405 nm. Because the 5P{sub 3/2} state has a smaller linewidth than the 4P{sub 3/2} state, the Doppler limit is reduced from 145 {mu}K to 24 {mu}K, and we observe temperatures as low as 63(6) {mu}K. The density of trapped atoms also increases, due to reduced temperature and reduced expulsive light forces. We measure a two-body loss coefficient of {beta}=1.4(1)x10{sup -10} cm{sup 3}/s near saturation intensity, and estimate an upper bound of 8x10{sup -18} cm{sup 2} for the ionization cross section of the 5P state at 405 nm. The combined temperature and density improvement in the 405 nm MOT is a twenty-fold increase in phase-space density over our 767 nm MOT, showing enhanced precooling for quantum gas experiments. A qualitatively similar enhancement is observed in a 405 nm MOT of bosonic {sup 41}K.

  4. 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.

  5. 3.8 W of cw blue light generated by intracavity frequency doubling of a 946-nm Nd:YAG laser with LBO

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Peng, H.; Hou, W.; Peng, Q.; Geng, A.; Guo, L.; Cui, D.; Xu, Z.

    2006-05-01

    Efficient cw intracavity frequency doubling of a diode-end-pumped Nd:YAG laser operating on 4 F 3/2→4 I 9/2 transitions at 946 nm has been demonstrated. A symmetrical cavity with two composite laser rods was designed, which divides the pump power between the two composite laser rods, allowing for greater power scalability. A 30-mm-long LiB3O5 (LBO) crystal, cut for critical type I phase matching at 57 °C, was used for the intracavity frequency doubling of the laser. A maximum output power of 3.8 W in the blue spectral range at 473 nm has been achieved at 39 W of pump power. The beam quality M2 value is 2.3 in both horizontal and vertical dimensions.

  6. Study of Methods for Producing a Tunable UV Laser for Spectroscopy at 243nm.

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Shiner, David

    2002-05-01

    We are beginning an experiment to precisely measure the 1S to 2S interval in atomic tritium. A narrow bandwidth tunable source of several mW at 243nm is required. We seek methods that are less expensive and cumbersome than traditional dye or Ti Sapphire lasers. An all solid state approach has been demonstrated [Zimmermann, Vuletic, Hemmerich and Hansch, Appl. Phys. Lett. 66 p2318, 1995] using a MOPA semiconductor laser with two resonant doubling cavities using KNbO3 and BBO. We study this approach but with possible improvements using PPLN as an alternative to KNbO3 and using CLBO for doubling 486nm as an alternative to BBO. Other IR laser sources are also considered. The current status of our investigations will be presented

  7. 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.

  8. 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.

  9. 40W high beam quality 532nm green laser with LBO intracavity-frequecy-doubling

    NASA Astrophysics Data System (ADS)

    Liu, Xuesheng; Li, Jing; Liu, Youqiang; Wang, Zhiyong

    2014-12-01

    A high-power high-beam-quality 1064nm Nd:YAG rod laser and SHG by intracavity-frequency-doubling are reported. With two common side-pumped Nd:YAG rod modules in the short cavity, we achieved an 78.5W near diffraction-limited pulsed wave 1064nm laser(M2=1.5) with pulse frequency 30kHz, pulse width 94ns and a good power stability of +/-1% for over two hours. Finally, a 40W pulsed green laser with pulse width of 92ns in a near diffraction-limited beam (M2=1.45) is generated using an LBO crystal as the frequency doubler in the cavity.

  10. 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.

  11. 1357 nm passively Q-switched crystalline ceramic laser based on multilayer graphene

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Zhang, Huanian; Wang, Qingpu; Xu, Shicai; Fang, Jiaxiong

    2016-05-01

    1357 nm single wavelength passively Q-switched Nd:YAG ceramic lasers are demonstrated with a multilayer graphene sheets saturable absorber (SA). During an increase in the incident pump power, the laser exhibited stable Q-switched oscillation, which showed that our graphene SA provided Q-switched modulation successfully. The maximum average output power was 340 mW, and the corresponding pulse width, pulse repetition rate, single pulse energy and peak power were 380 ns, 209 kHz, 53 μJ and 139 W, respectively. Our results illustrate that graphene can be used as an SA for 1357 nm passively Q-switched Nd:YAG ceramic lasers.

  12. 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.

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

    PubMed

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

    2016-06-01

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

  14. 224 nm Deep-UV laser for native fluorescence, a new opportunity for biomolecules detection.

    PubMed

    Bonnin, Cécile; Matoga, Myriam; Garnier, Nicolas; Debroche, Claude; de Vandière, Bruno; Chaminade, Pierre

    2007-07-13

    A new highly sensitive and compact 224 nm laser-induced native fluorescence (LINF) detector was developed using a new generation of deep-UV laser and an innovating elliptical flow cell. The use of deep-UV excitation at 224 nm allows to achieve fluorescence detection of an important range of molecules containing a single aromatic ring. The LINF detector was first evaluated in liquid chromatography. An improvement of a factor 500 over a conventional fluorimeter is reached with a limit of detection (LOD) of 1.5 pmole for ibuprofen. LODs were in the nanomole range for phenylalanine and in the picomole range for tyrosine and tryptophan. The LINF detector is able to detect the same levels of peptides concentrations as an ESI-ion trap spectrometer used in scan mode. In this application, LINF outperforms the UV detection at 214 or 254 nm and could be used with different additives with no noticeable effect on the detection. PMID:17174961

  15. 980-nm Q-switched photonic crystal fiber laser by MoS2 saturable absorber

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Liang, Boxing; Su, Meng; Zhang, Yuefei; Zhao, Yan; Zhang, Mengmeng; Ma, Chunmei; Su, Ning

    2016-05-01

    We demonstrate a 980-nm Q-switch Yb-doped photonic crystal fiber laser by a multilayer molybdenum sulfide polymer composite as the broadband saturable absorber which is prepared by the chemical vapor deposition method. We achieve passively Q-switching operations at 978 nm with the pulse width of 2.7 and 0.63 μs, corresponding to the repetition rate of 212 and 221 kHz, respectively. The maximum output power is 127 mW. It is the first time that MoS2 Q-switched Yb-doped photonic crystal fiber laser at 980 nm is demonstrated. The experimental results show that few-layer MoS2 is a promising broadband saturable absorber material.

  16. White-Light Emission from Silicone Rubber Modified by 193 nm ArF Excimer Laser

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Sekine, Daisuke; Inoue, Narumi; Yamashita, Tsugito

    2007-04-01

    The photochemical surface modification of silicone ([SiO(CH3)2]n) rubber has been successfully demonstrated using a 193 nm ArF excimer laser, and white light of strong intensity was emitted upon exposure to a 325 nm He-Cd laser. The photoluminescence spectra of the modified silicone showed broad peaks centered at 410, 550, and 750 nm wavelengths. The modified surface was carbon-free silicon oxide, and the chemical composition ratio of O/Si was approximately 2. However, the surface was not silica glass (SiO2), as clarified by IR spectroscopy. Instead, nanometer-size particles of silicon oxide were formed on the surface of the modified silicone rubber.

  17. 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)

  18. 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

  19. Narrow-linewidth tunable laser working at 633 nm suitable for industrial interferometry

    NASA Astrophysics Data System (ADS)

    Minh, Tuan Pham; Hucl, Václav; Čížek, Martin; Mikel, Břetislav; Hrabina, Jan; Řeřucha, Šimon; Číp, Ondřej; Lazar, Josef

    2015-05-01

    Semiconductor lasers found a foothold in many fields of human activities, mainly thanks to its small size, low cost and high energy efficiency. Recent methods for accurate distance measurement in industrial practice use principles of laser interferometry, which are based on lasers operating in the visible spectrum. When the laser beam is visible the alignment of the industrial interferometer makes the measuring process easier. Traditional lasers for these purposes for many decades - HeNe gas laser - have superb coherence properties but small tunable range. On the other hand laser diodes are very useful lasers but only if the active layer of the semiconductor equips with a passive selective element that will increase the quality of their own resonator and also prevents the structure of its higher longitudinal modes. The main aim of the work is a design of the laser source based on a new commercial available laser diode with Distributed Bragg Reflector structure, butterfly package and fibre coupled output. The ultra-low noise injection current source, stable temperature controller and supply electronic equipment were developed with us and experimentally tested with this laser for the best performances required of the industrial interferometry field. The work also performs a setup for frequency noise properties investigation with an unbalanced fibre based Mach-Zehnder interferometer and 10 m long fibre spool inserted in the reference arm. The work presents the way to developing the narrow-linewidth operation the DBR laser with the wide tunable range up to more than 1 nm of the operation wavelength at the same time. Both capabilities predetermine this complex setup for the industrial interferometry application as they are the long distance surveying or absolute scale interferometry.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

    2016-04-01

    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. PMID:26836057

  5. Standoff detection of biological agents using laser induced fluorescence—a comparison of 294 nm and 355 nm excitation wavelengths

    PubMed Central

    Farsund, Øystein; Rustad, Gunnar; Skogan, Gunnar

    2012-01-01

    Standoff detection measuring the fluorescence spectra of seven different biological agents excited by 294 nm as well as 355 nm wavelength laser pulses has been undertaken. The biological warfare agent simulants were released in a semi-closed aerosol chamber at 210 m standoff distance and excited by light at either of the two wavelengths using the same instrument. Significant differences in several of the agents’ fluorescence response were seen at the two wavelengths. The anthrax simulants’ fluorescence responses were almost an order of magnitude stronger at the shorter wavelength excitation. However, most importantly, the fluorescence spectra were significantly more dissimilar at 294 nm than at 355 nm excitation with ~7 nm spectral resolution. This indicates that classification of the substances should be possible with a lower error rate for standoff detection using 294 nm rather than 355 nm excitation wavelength, or even better, utilizing both. PMID:23162732

  6. 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

  7. 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.

  8. Photodissociation of 2, 4, 6-trinitrotoluene with a Nd:YAG laser at 532nm

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Shen, Ruiqi; Ye, Yinghua; Wu, Lizhi; Hu, Yan; Zhu, Peng

    2015-05-01

    2, 4, 6-Trinitrotoluene (TNT) belongs to the group of aromatic nitro compounds which have extended use in industrial applications, in particular as explosives or additives to explosives. Understanding the initial step of laser induced decomposition of common explosives is important to the reliability and safety of laser initiators and firing systems. Lasers coupled with mass spectrometer find wide application in photochemical studies for identification of different ions formed due to photoexcitation/ionization of molecules by laser. In this paper, a pulsed Nd: YAG (15ns, 532nm) laser was used for ionizating the condensed TNT sample, and the ions produced in the ionization process were detected by a time of flight mass spectrometer (TOFMS). The influence of laser fluence and the delay time to the decomposition was also studied. According to the assignment of both positive and negative ions, possible laser induced dissociation pathways were proposed. The results may tell much about the initiation process and the chemical reaction that may occur in TNT when exposed to laser pulse.

  9. 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. PMID:22892613

  10. Extensive angiokeratoma circumscriptum - successful treatment with 595-nm variable-pulse pulsed dye laser and 755-nm long-pulse pulsed alexandrite laser.

    PubMed

    Baumgartner, Ján; Šimaljaková, Mária; Babál, Pavel

    2016-06-01

    Angiokeratomas are rare vascular mucocutaneous lesions characterized by small-vessel ectasias in the upper dermis with reactive epidermal changes. Angiokeratoma circumscriptum (AC) is the rarest among the five types in the current classification of angiokeratoma. We present a case of an extensive AC in 19-year-old women with Fitzpatrick skin type I of the left lower extremity, characterized by a significant morphological heterogeneity of the lesions, intermittent bleeding, and negative psychological impact. Histopathological examination after deep biopsy was consistent with that of angiokeratoma. The association with metabolic diseases (Fabry disease) was excluded by ophthalmological, biochemical, and genetic examinations. Nuclear magnetic resonance imaging has not detected deep vascular hyperplasia pathognomic for verrucous hemangioma. The combined treatment with 595-nm variable-pulse pulsed dye laser (VPPDL) and 755-nm long-pulse pulsed alexandrite laser (LPPAL) with dynamic cooling device led to significant removal of the pathological vascular tissue of AC. Only a slight degree of secondary reactions (dyspigmentations and texture changes) occurred. No recurrence was observed after postoperative interval of 9 months. We recommend VPPDL and LPPAL for the treatment of extensive AC. PMID:26736060

  11. Elemental fractionation in 785 nm picosecond and femtosecond laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-05-01

    Elemental fractionation and ICP-MS signal response were investigated for two different pulse width laser beams originating from the same laser system. Femtosecond and picosecond laser beams at pulse widths of 130 fs and 110 ps, respectively, and wavelength of 785 nm were used to ablate NIST 610 synthetic glass and SRM 1107 Naval Brass B at the same spot for 800 to 1000 laser pulses at different repetition rates (5 to 50 Hz). Elemental fractionation was found to depend on repetition rate and showed a trend with femtosecond laser ablation that is opposite to that observed in picosecond laser ablation for most measured isotopes. ICP-MS signal intensity was higher in femtosecond than picosecond LA-ICP-MS in both NIST 610 and naval brass when ablation was conducted under the same fluence and repetition rate. The differences in signal intensity were partly related to differences in particle size distribution between particles generated by femtosecond and picosecond laser pulses and the consequent differences in transport and ionization efficiencies. The main reason for the higher signal intensity resulting from femtosecond laser pulses was related to the larger crater sizes compared to those created during picosecond laser ablation. Elemental ratios measured using 66Zn/63Cu, 208Pb/238U, 232Th/238U, 66Zn/232Th and 66Zn/208Pb were found to change with the number of laser pulses with data points being more scattered in picosecond than femtosecond laser pulses. Reproducibility of replicate measurements of signal intensities, fractionation and elemental ratios was better for fs-LA-ICP-MS (RSD ~ 3 to 6%) than ps-LA-ICP-MS (RSD ~ 7 to 11%).

  12. Influence of consecutive picosecond pulses at 532 nm wavelength on laser ablation of human teeth

    NASA Astrophysics Data System (ADS)

    Mirdan, Balsam M.; Antonelli, Luca; Batani, Dimitri; Jafer, Rashida; Jakubowska, Katarzyna; Tarazi, Saad al; Villa, Anna Maria; Vodopivec, Bruno; Volpe, Luca

    2014-07-01

    The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin-enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.

  13. High-power and low-intensity noise laser at 1064  nm.

    PubMed

    Guiraud, Germain; Traynor, Nicholas; Santarelli, Giorgio

    2016-09-01

    We have developed a single-frequency, narrow-linewidth (Δν<50  kHz) laser operating at 1064 nm with a high output power (50 W). The laser is based on an ytterbium-doped fiber master oscillator power amplifier architecture with an output beam at the diffraction limit. An output power of 50 W is obtained with two amplification stages using a 50 mW diode laser seeder. We have carefully studied the relative intensity noise at each amplification stage. The detrimental effect due to stimulated Brillouin scattering on residual amplitude noise has been observed on the high-power booster stage. After careful optimization, this laser exhibits low intensity noise with a RMS value equal to 0.012% (1 kHz/10 MHz) at 50 W. PMID:27607967

  14. 0.26-Hz-linewidth ultrastable lasers at 1557 nm

    PubMed Central

    Wu, Lifei; Jiang, Yanyi; Ma, Chaoqun; Qi, Wen; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2016-01-01

    Narrow-linewidth ultrastable lasers at 1.5 μm are essential in many applications such as coherent transfer of light through fiber and precision spectroscopy. Those applications all rely on the ultimate performance of the lasers. Here we demonstrate two ultrastable lasers at 1557 nm with a most probable linewidth of 0.26 Hz by independently frequency-stabilizing to the resonance of 10-cm-long ultrastable Fabry-Pérot cavities at room temperature. The fractional frequency instability of each laser system is nearly 8 × 10−16 at 1–30 s averaging time, approaching the thermal noise limit of the reference cavities. A remarkable frequency instability of 1 × 10−15 is achieved on the long time scale of 100–4000 s. PMID:27117356

  15. High-power diode lasers with an aluminium-free active region at 915 nm

    NASA Astrophysics Data System (ADS)

    Michel, N.; Hassiaoui, I.; Calligaro, M.; Lecomte, M.; Parillaud, O.; Krakowski, M.; Borruel, L.; García-Tijero, J.-M.; Esquivias, I.; Sukecki, S.; Larkins, E. C.

    2005-11-01

    We have developed high-power lasers, which are based on an Al-free active region at 915 nm. The laser structure has very low internal losses of 0.5 cm-1, a very low transparency current density of 86 A/cm2, and a high internal quantum efficiency of 86%. Based on these good results, we have realised narrow-aperture, index-guided tapered lasers which deliver 1 W CW with and M2 beam quality factor of 3.0 using both the 1/e2 and standard-deviation methods. We have also fabricated index-guided tapered lasers with a Clarinet shape, which deliver 0.65 W CW with an M2 beam quality factor of less than 1.5 at 1/e2, and less than 2.5 using the standard deviation method.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  17. 980-nm, 15-W cw laser diodes on F-mount-type heat sinks

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  18. 355, 532, and 1064 nm picosecond laser interaction with grass tissues

    NASA Astrophysics Data System (ADS)

    Kim, Jaehun; Ki, Hyungson

    2012-12-01

    In this article, we investigate how 355, 532, and 1064 nm picosecond lasers interact with grass tissues. We have identified five interaction regimes, and based on this classification, interaction maps have been constructed from a systematic experiment. The optical properties of light absorbing grass constituents are studied theoretically in order to understand how and how much light is absorbed by grass tissues. Scanning electron microscopy and optical microscopy are employed for observing morphological and structural changes of grass tissues. To the best of the authors' knowledge, this is the first investigation into laser interaction with plant leaves and reveals some fundamental findings regarding how a laser interacts with grass tissues and how plant leaves can be processed using lasers.

  19. Red and orange laser operation of Pr:KYF4 pumped by a Nd:YAG/LBO laser at 469.1 nm and a InGaN laser diode at 444 nm.

    PubMed

    Xu, B; Starecki, F; Pabœuf, D; Camy, P; Doualan, J L; Cai, Z P; Braud, A; Moncorgé, R; Goldner, Ph; Bretenaker, F

    2013-03-11

    We report the basic luminescence properties and the continuous-wave (CW) laser operation of a Pr(3+)-doped KYF(4) single crystal in the Red and Orange spectral regions by using a new pumping scheme. The pump source is an especially developed, compact, slightly tunable and intra-cavity frequency-doubled diode-pumped Nd:YAG laser delivering a CW output power up to about 1.4 W around 469.1 nm. At this pump wavelength, red and orange laser emissions are obtained at about 642.3 and 605.5 nm, with maximum output powers of 11.3 and 1 mW and associated slope efficiencies of 9.3% and 3.4%, with respect to absorbed pump powers, respectively. For comparison, the Pr:KYF(4) crystal is also pumped by a InGaN blue laser diode operating around 444 nm. In this case, the same red and orange lasers are obtained, but with maximum output powers of 7.8 and 2 mW and the associated slope efficiencies of 7 and 5.8%, respectively. Wavelength tuning for the two lasers is demonstrated by slightly tilting the crystal. Orange laser operation and laser wavelength tuning are reported for the first time. PMID:23482128

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

    PubMed

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

    2015-12-01

    It has long been argued that light from a laser diode is superior to light from a light-emitting diode (LED) in terms of its effect on biological tissues. In order to shed light on this ongoing debate, we compared the antimicrobial effect of light emitted from a 405-nm LED with that of a 405-nm laser on methicillin-resistant Staphylococcus aureus (MRSA) at comparable fluences. We cultured 5 × 10(6) CFU/ml MRSA on tryptic soy agar and then irradiated culture plates once, twice, or thrice with either LED or laser light using 40, 54, 81, or 121 J/cm(2) fluence at 15-, 30-, or 240-min time interval between irradiation. Cultures were incubated immediately after irradiation at 37 °C for 24 h before imaging and counting remnant bacterial colonies. Regardless of the device used, LED or laser, irradiation at each fluence resulted in statistically significant bacterial growth suppression compared to non-irradiated controls (p < 0.0001). The antimicrobial effect of both light sources, LED and laser, was not statistically different at each fluence in 35 of the 36 experimental trials. Bacterial growth suppression achieved with either source of light increased with repeated irradiation, particularly at the 15- or 30-min treatment time interval. Thus, we conclude that the antimicrobial effect of 405-nm laser and 405-nm LED on MRSA is similar; neither has a superior antimicrobial effect when compared to the other. PMID:26362142

  1. Double Brillouin frequency spaced multiwavelength Brillouin-erbium fiber laser with 50 nm tuning range

    NASA Astrophysics Data System (ADS)

    Zhao, J. F.; Liao, T. Q.; Zhang, C.; Zhang, R. X.; Miao, C. Y.; Tong, Z. R.

    2012-09-01

    A 50 nm tuning range multiwavelength Brillouin-erbium fiber laser (MWBEFL) with double Brillouin frequency spacing is presented. Two separated gain blocks with symmetrical architecture, consisted by erbium-doped fiber amplifiers (EDFAs) and Brillouin gain media, are used to generate double Brillouin frequency spacing. The wider tuning range is realized by eliminating the self-lasing cavity modes existing in conventional MWBEFLs because of the absence of the physical mirrors at the ends of the linear cavity. The Brillouin pump (BP) is preamplified by the EDFA before entering the single-mode fiber (SMF), which leads to the reduction of threshold power and the generation enhancement of Brillouin Stokes (BS) signals. Four channels with 0.176 nm spacing are achieved at 2 mW BP power and 280 mW 980 nm pump power which can be tuned from 1525 to 1575 nm.

  2. Fabrication of 250-nm-hole arrays in glass and fused silica by UV laser ablation

    NASA Astrophysics Data System (ADS)

    Karstens, R.; Gödecke, A.; Prießner, A.; Ihlemann, J.

    2016-09-01

    Parallel nanohole drilling in glass using an ArF excimer laser (193 nm) is demonstrated. For the first time, hole arrays with 500 nm pitch and individual holes with 250 nm diameter and more than 100 nm depth are fabricated by phase mask imaging using a Schwarzschild objective. Holes in soda lime glass are drilled by direct ablation; fused silica is processed by depositing a SiOx-film on SiO2, patterning the SiOx by ablation, and finally oxidizing the remaining SiOx to SiO2. Thermally induced ordered dewetting of noble metal films deposited on such templates may be used for the fabrication of plasmonic devices.

  3. 980nm laser for difficult-to-treat basal cell carcinoma

    NASA Astrophysics Data System (ADS)

    Derjabo, A. D.; Cema, I.; Lihacova, I.; Derjabo, L.

    2013-06-01

    Begin basal cell carcinoma (BCC) is most common skin cancer over the world. There are around 20 modalities for BCC treatment. Laser surgery is uncommon option. We demonstrate our long term follow up results. Aim: To evaluate long term efficacy of a 980nm diode laser for the difficult-to-treat basal cell carcinoma. Materials and Methods: 167 patients with 173 basal cell carcinoma on the nose were treated with a 980 nm diode laser from May 1999 till May 2005 at Latvian Oncology center. All tumors were morphologically confirmed. 156 patients were followed for more than 5 years. Results: The lowest recurrence rate was observed in cases of superficial BCC, diameter<6mm bet the highest recurrence rate was in cases of infiltrative BCC and nodular recurrent BCC. Conclusions: 980 nm diode laser is useful tool in dermatology with high long term efficacy, good acceptance by the patients and good cosmetics results.

  4. Low-cost 420nm blue laser diode for tissue cutting and hemostasis

    NASA Astrophysics Data System (ADS)

    Linden, Kurt J.

    2016-03-01

    This paper describes the use of a 420 nm blue laser diode for possible surgery and hemostasis. The optical absorption of blood-containing tissue is strongly determined by the absorption characteristics of blood. Blood is primarily comprised of plasma (yellowish extracellular fluid that is approximately 95% water by volume) and formed elements: red blood cells (RBCs), white blood cells (WBCs) and platelets. The RBCs (hemoglobin) are the most numerous, and due to the spectral absorption characteristics of hemoglobin, the optical absorption of blood has a strong relative maximum value in the 420 nm blue region of the optical spectrum. Small, low-cost laser diodes emitting at 420 nm with tens of watts of continuous wave (CW) optical power are becoming commercially available. Experiments on the use of such laser diodes for tissue cutting with simultaneous hemostasis were carried out and are here described. It was found that 1 mm deep x 1 mm wide cuts can be achieved in red meat at a focused laser power level of 3 W moving at a velocity of ~ 1 mm/s. The peripheral necrosis and thermal damage zone extended over a width of approximately 0.5 mm adjacent to the cuts. Preliminary hemostasis experiments were carried out with fresh equine blood in Tygon tubing, where it was demonstrated that cauterization can occur in regions of intentional partial tubing puncture.

  5. A novel single frequency stabilized Fabry-Perot laser diode at 1590 nm for gas sensing

    NASA Astrophysics Data System (ADS)

    Weldon, Vincent; Boylan, Karl; Corbett, Brian; McDonald, David; O'Gorman, James

    2002-09-01

    A novel single frequency stabilized Fabry-Perot (SFP) laser diode with an emission wavelength of λ=1590 nm for H 2S gas sensing is reported. Sculpting of the multi-mode spectral distribution of a FP laser to achieve single frequency emission is carried out using post growth photolitographic processing of the device. The resulting longitudinal-mode controlled FP laser has a stabilized single frequency emission with a side mode suppression ratio (SMSR) of 40 dB. The application of this device to spectroscopic based H 2S sensing is demonstrated by targeting absorption lines in the wavelength range 1588≤ λ≤1591 nm. Using wavelength modulation spectroscopy (WMS), a low detection limit of 120 ppm.m.Hz -1/2 was estimated while targeting the absorption line at 1590.08 nm. These initial results demonstrate the potential of the stabilized FP laser diode at this wavelength as a tunable, single frequency source for spectroscopic based gas sensing.

  6. Thin film contamination effects on laser-induced damage of fused silica surfaces at 355 nm

    SciTech Connect

    Burnham, A. K.; Cordillot, C.; Fornier, A.; Genin, F. Y.; Rubenchick, A. M.; Schirmann, D.; Yoshiyama, J.

    1998-07-28

    Fused silica windows were artificially contaminated to estimate the resistance of target chamber debris shields against laser damage during NIF operation. Uniform contamination thin films (1 to 5 nm thick) were prepared by sputtering various materials (Au, Al, Cu, and B4C). The loss of transmission of the samples was first measured. They were then tested at 355 nm in air with an 8-ns Nd:YAG laser. The damage morphologies were characterized by Nomarski optical microscopy and SEM. Both theory and experiments showed that metal contamination for films as thin as 1 nm leads to a substantial loss of transmission. The laser damage resistance dropped very uniformly across the entire surface (e.g. 6 J/cm2 for 5 nm of Cu). The damage morphology characterization showed that contrary to clean silica, metal coated samples did not produce pits on the surface. B4C coated silica, on the other hand, led to a higher density of such damage pits. A model for light absorption in the thin film was coupled with a simple heat deposition and diffusion model to perform preliminary theoretical estimates of damage thresholds. The estimates of the loss due to light absorption and reflection pointed out significant .differences between metals (e.g. Al and Au). The damage threshold predictions were in qualitative agreement with experimental measurements.

  7. Wavelength tunable high-power single-mode 1060-nm DBR lasers

    NASA Astrophysics Data System (ADS)

    Li, Jin; Kuksenkov, Dmitri V.; Liu, Wayne; Li, Yabo; Visovsky, Nick J.; Pikula, Dragan; Heberle, Albert P.; Brown, Gordon C.; Piech, Garrett A.; Butler, Douglas L.; Zah, Chung-en

    2012-03-01

    The wavelength tunable 1060-nm distributed Bragg reflector (DBR) laser chip consists of three sections: a gain section for lasing, and phase and DBR sections for wavelength control. A micro-heater is lithographically integrated on the top of the DBR section to tune the emission wavelength. The phase section is designed with either a top heater or by current injection to provide fine tuning of the wavelength. The wavelength tuning efficiency of our DBR laser is approximately 9 nm/W at the laser heat sink temperature of 25°C. Single-mode output powers of 686 mW and 605 mW were obtained at a CW gain drive current of 1.25 A and heat sink temperatures of 25°C and 60°C, respectively. Gain-switching by applying 1.1 GHz sinusoidal signal mixed with 600 mA DC injection current produced approximately 58 ps long optical pulses with 3.1 W peak power and 228 mW average power. The average power increased to 267 mW and pulse width broadened to 70 ps with DC bias of 700 mA. In CW operation, one of the applications for high-power single-mode DBR lasers is for non-linear frequency conversion. The light emitted from the 1060-nm DBR laser chip was coupled into a single-mode periodically poled lithium niobate (PPLN) crystal waveguide. Up to 350 mW optical power at 530 nm with the wall-plug efficiency of up to 15% was demonstrated.

  8. Anti-Fungal Laser Treatment of Paper: A Model Study with a Laser Wavelength of 532 nm

    NASA Astrophysics Data System (ADS)

    Pilch, E.; Pentzien, S.; Mädebach, H.; Kautek, W.

    Biodeterioration of organic cultural heritage materials is a common problem. Particularly the removal of discoloration caused by fungal pigments is yet an unsolved problem in paper conservation. In the present study, cellulose (cotton and linters) and 16th century paper (rag), were incubated with several fungi types, such as Cladosporium, Epicoccum, Alternaria, Chaetomium, Aspergillus, Trichophyton, and Penicillium on agar for three weeks. Then they were immersed in 70% Ethanol for removal of hyphae and mycelia and deactivation of the remaining conidia. These specimens were laser-treated in a computer-controlled laser cleaning system with a high pulse energy diode pumped Q-switched Nd:YAG laser operating at 532 nm and a pulse duration of 8 ns. Colour differences were determined spectrophotometrically. Best cleaning results were observed with fungi such as Penicillium and Alternaria. Dry laser cleaning generally turned out to be superb over wet bleaching approaches.

  9. Lead extraction by selective operation of a nanosecond-pulsed 355nm laser

    NASA Astrophysics Data System (ADS)

    Herzog, Amir; Bogdan, Stefan; Glikson, Michael; Ishaaya, Amiel A.; Love, Charles

    2016-03-01

    Lead extraction (LE) is necessary for patients who are suffering from a related infection, or in opening venous occlusions that prevent the insertion of additional lead. In severe cases of fibrous encapsulation of the lead within a vein, laser-based cardiac LE has become one of the foremost methods of removal. In cases where the laser radiation (typically at 308 nm wavelength) interacts with the vein wall rather than with the fibrotic lesion, severe injury and subsequent bleeding may occur. Selective tissue ablation was previously demonstrated by a laser operating in the UV regime; however, it requires the use of sensitizers (e.g.: tetracycline). In this study, we present a preliminary examination of efficacy and safety aspects in the use of a nanosecond-pulsed solid-state laser radiation, at 355 nm wavelength, guided in a catheter consisting of optical fibers, in LE. Specifically, we demonstrate a correlation between the tissue elasticity and the catheter advancement rate, in ex-vivo experiments. Our results indicate a selectivity property for specific parameters of the laser radiation and catheter design. The selectivity is attributed to differences in the mechanical properties of the fibrotic tissue and a normal vein wall, leading to a different photomechanical response of the tissue's extracellular matrix. Furthermore, we performed successful in-vivo animal trials, providing a basic proof of concept for using the suggested scheme in LE. Selective operation using a 355 nm laser may reduce the risk of blood vessel perforation as well as the incidence of major adverse events.

  10. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    NASA Astrophysics Data System (ADS)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup, Birgitte

    2010-04-01

    High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality. By adapting a bar geometry, the output power could be scaled even up to several tens of watts. Unfortunately, the high divergence which is a characteristic feature of the bar geometry could lead to a degradation of the overall beam quality of the laser bar. However, spectral beam combining is an effective solution for preserving the beam quality of the bar in the range of that of a single emitter and at the same time, enabling the power scaling. We report spectral beam combining applied to a 12 emitter tapered laser bar at 980 nm. The external cavity has been designed for a wavelength separation of 4.0 nm between the emitters. An output power of 9 W has been achieved at an operating current of 30 A. The combined beam had an M2 value (1/e2) of 5.3 along the slow axis which is comparable to that of a single tapered emitter on the laser bar. The overall beam combining efficiency was measured to be 63%. The output spectrum of the individual emitters was narrowed considerably. In the free running mode, the individual emitters displayed a broad spectrum of the order of 0.5-1.0 nm while the spectral width has been reduced to 30-100 pm in the spectral beam combining mode.

  11. 193 nm excimer laser sclerostomy in pseudophakic patients with advanced open angle glaucoma.

    PubMed Central

    Allan, B D; van Saarloos, P P; Cooper, R L; Constable, I J

    1994-01-01

    A modified open mask system incorporating an en face air jet to dry the target area during ablation and a conjunctival plication mechanism, which allows ab externo delivery of the 193 nm excimer laser without prior conjunctival dissection, has been developed to form small bore sclerostomies accurately and atraumatically. Full thickness sclerostomies, and sclerostomies guarded by a smaller internal ostium can be created. A pilot therapeutic trial was conducted in pseudophakic patients with advanced open angle glaucoma. Six full thickness sclerostomies (200 microns and 400 microns diameter) and three guarded sclerostomies were created in nine patients by 193 nm excimer laser ablation (fluence per pulse 400 mJ/cm2, pulse rate 16 Hz, air jet pressure intraocular pressure +25 mm Hg). After 6 months' follow up, intraocular pressure was controlled (< or = 16 mm Hg) in eight of the nine patients (6/9 without medication). Early postoperative complications included hyphaema (trace--2.5 mm) (6/9), temporary fibrinous sclerostomy occlusion (4/9), profound early hypotony (all patients without fibrinous occlusion), and suprachoroidal haemorrhage in one case. Conjunctival laser wounds were self sealing. Small bore laser sclerostomy procedures are functionally equivalent to conventional full thickness procedures, producing early postoperative hypotony, with an increased risk of suprachoroidal haemorrhage in association with this. Further research is required to improve control over internal guarding in excimer laser sclerostomy before clinical trials of this technique can safely proceed. Images PMID:8148335

  12. Q-switched Erbium-doped fiber laser at 1600 nm for photoacoustic imaging application

    NASA Astrophysics Data System (ADS)

    Piao, Zhonglie; Zeng, Lvming; Chen, Zhongping; Kim, Chang-Seok

    2016-04-01

    We present a nanosecond Q-switched Erbium-doped fiber (EDF) laser system operating at 1600 nm with a tunable repetition rate from 100 kHz to 1 MHz. A compact fiber coupled, acousto-optic modulator-based EDF ring cavity was used to generate a nanosecond seed laser at 1600 nm, and a double-cladding EDF based power amplifier was applied to achieve the maximum average power of 250 mW. In addition, 12 ns laser pulses with the maximum pulse energy of 2.4 μJ were obtained at 100 kHz. Furthermore, the Stokes shift by Raman scattering over a 25 km long fiber was measured, indicating that the laser can be potentially used to generate the high repetition rate pulses at the 1.7 μm region. Finally, we detected the photoacoustic signal from a human hair at 200 kHz repetition rate with a pulse energy of 1.2 μJ, which demonstrates that a Q-switched Er-doped fiber laser can be a promising light source for the high speed functional photoacoustic imaging.

  13. Treatment of facial telangiectasias with a diode-pumped Nd:YAG laser at 532 nm

    NASA Astrophysics Data System (ADS)

    Cassuto, Daniel A.; Ancona, Deborah M.; Emanuelli, Guglielmo

    2000-06-01

    Facial telangiectasias are a common cause of cosmetic concern. Current treatment modalities present various effects and limits. The pulsed dye laser has been considered the golden standard in efficacy and safety. Unfortunately it causes postoperative intracutaneous hematomata that discourage many patients form undergoing this treatment. Several other vascular lasers are disadvantaged by the risk of hypopigmented and atrophic scars. We assessed a recent powerful version of the potassium titanyl phosphate 532 nm laser, that can deliver sufficient energy in single pulses lasting 10-50 msec. Collateral damage is reduced while the heating of the vessel is slow enough to avoid explosive photothermolysis with its associated purpura. Sixty-six patients with facial telangiectasias were treated. In 62/66 patients, we achieved a 75 percent-100 percent clearance of the lesions, while two treatments were needed to reach an acceptable clearance in the remaining 4/66 patients. The overall need for more sessions was well tolerated, because the acceptable postoperative appearance allowed patients to continue normal business and social activities between treatments. No permanent complications or undesired effects were noted. The KTP/532nm laser is also being tested in combined laser-sclerotherapy of fine leg capillary telangiectasias with encouraging results.

  14. Precision drilling of fused silica with 157-nm excimer laser radiation

    NASA Astrophysics Data System (ADS)

    Temme, Thorsten; Ostendorf, Andreas; Kulik, Christian; Meyer, Klaus

    2003-07-01

    μFor drilling fused silica, mechanical techniques like with diamond drills, ultrasonic machining, sand blasting or water jet machining are used. Also chemical techniques like laser assisted wet etching or thermal drilling with CO2-lasers are established. As an extension of these technologies, the drilling of micro-holes in fused silica with VUV laser radiation is presented here. The high absorption of the 157 nm radiation emitted by the F2 excimer laser and the short pulse duration lead to a material ablation with minimised impact on the surrounding material. Contrary to CO2-laser drilling, a molten and solidified phase around the bore can thus be avoided. The high photon energy of 7.9 eV requires either high purity nitrogen flushing or operation in vacuum, which also effects the processing results. Depending on the required precision, the laser can be used for percussion drilling as well as for excimer laser trepanning, by applying rotating masks. Rotating masks are especially used for high aspect ratio drilling with well defined edges and minimised debris. The technology is suitable particularly for holes with a diameter below 200 μm down to some microns in substrates with less than 200 μm thickness, that can not be achieved with mechanical methods. Drilling times in 200 μm fused silica substrates are in the range of ten seconds, which is sufficient to compete with conventional methods while providing similar or even better accuracy.

  15. Laser transit anemometer software development program

    NASA Technical Reports Server (NTRS)

    Abbiss, John B.

    1989-01-01

    Algorithms were developed for the extraction of two components of mean velocity, standard deviation, and the associated correlation coefficient from laser transit anemometry (LTA) data ensembles. The solution method is based on an assumed two-dimensional Gaussian probability density function (PDF) model of the flow field under investigation. The procedure consists of transforming the data ensembles from the data acquisition domain (consisting of time and angle information) to the velocity space domain (consisting of velocity component information). The mean velocity results are obtained from the data ensemble centroid. Through a least squares fitting of the transformed data to an ellipse representing the intersection of a plane with the PDF, the standard deviations and correlation coefficient are obtained. A data set simulation method is presented to test the data reduction process. Results of using the simulation system with a limited test matrix of input values is also given.

  16. Development of high-power, 6 kHz, single-mode Ti:sapphire laser at 904 nm for generating 193 nm light

    NASA Astrophysics Data System (ADS)

    Tsuboi, Mizuki; Nakazato, Tomoharu; Onose, Takashi; Tanaka, Yuichi; Sarukura, Nobuhiko; Kakizaki, Kouji; Watanabe, Shuntaro

    2015-04-01

    A high power, 6 kHz, single-mode Ti:sapphire laser operating at 904 nm has been developed to produce a 193 nm light source. The output power was above 10 W with a bandwidth of 160 MHz. The Hänsch-Couillaud locking scheme was successfully applied to stabilize the frequency of the pulse laser. The thermal lens in the Ti:sapphire crystal having a focal length down to 10 mm along with strong astigmatism was compensated by distributing thermal load to three amplifiers with an even number of passes, resulting in a nearly diffraction limited beam. This Ti:sapphire laser contributed to the generation of 193 nm light with an output power above 200 mW.

  17. Diode pumped Pr3+:LiYF4-BBO ultraviolet laser at 320 nm

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    A diode pumped Pr3+:LiYF4 laser at 639.5 nm has been demonstrated. With an incident pump power of 920 mW, the maximum red output power was 272 mW. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a maximum ultraviolet power of 23 mW by using a β-BaB2O4 (BBO) nonlinear crystal. To the best of our knowledge, this is the first report on continuous-wave ultraviolet generation by intracavity frequency doubling Pr3+:LiYF4 laser.

  18. Stable Gain-Switched Thulium Fiber Laser With 140-nm Tuning Range

    NASA Astrophysics Data System (ADS)

    Wang, Fengqiu; Meng, Yafei; Kelleher, Edmund; Guo, Guoxiang; Li, Yao; Xu, Yongbing; Zhu, Shining

    2016-06-01

    We demonstrate a gain-switched thulium fiber laser that can be continuously tuned over 140 nm, while maintaining stable nanosecond single-pulse operation. To the best of our knowledge, this system represents the broadest tuning range for a gain-switched fiber laser. The system simplicity and wideband wavelength tunability combined with the ability to control the temporal characteristics of the gain-switched pulses mean this is a versatile source highly suited to a wide range of applications in the eye-safe region of the infrared, including spectroscopy, sensing and material processing, as well as being a practical seed source for pumping nonlinear processes.

  19. Q-switched 1329  nm Nd:CNGG laser.

    PubMed

    Xiao, Kun; Lin, Bin; Zhang, Qiu-Lin; Zhang, Dong-Xiang; Feng, Bao-Hua; He, Jing-Liang; Zhang, Huai-Jin; Wang, Ji-Yang

    2015-08-10

    We demonstrate a laser-diode-pumped Q-switched 1329 nm neodymium-doped calcium-niobium-gallium-garnet (Nd:CNGG) laser using a V:YAG crystal as a saturable absorber. An average output power of 353 mW and a repetition rate of 13.43 kHz for Q-switched pulses were obtained. The pulse width was from 124 to 151.4 ns under different pump powers. Output power of 685 mW was obtained without the V:YAG crystal inserted. PMID:26368377

  20. Disseminated superficial actinic porokeratosis improved with fractional 1927-nm laser treatments.

    PubMed

    Ross, Nicholas A; Rosenbaum, Lara E; Saedi, Nazanin; Arndt, Kenneth A; Dover, Jeffrey S

    2016-01-01

    Disseminated superficial actinic porokeratosis (DSAP) is an inherited disorder of keratinization readily diagnosed through clinical and histologic examination. While generally benign in nature, the lesions can have profound psychosocial implications for patients. Although no cure exists, a number of treatment modalities, from topical medications to laser and light devices, have been reported with variable success. The authors report two cases of DSAP treated with the 1927-nm thulium fiber fractional laser along with a review of the treatment literature for DSAP. This therapy is convenient and safe with nearly no downtime or morbidity associated with pigment or textural changes. PMID:26820042

  1. Linearly frequency-modulated pulsed single-frequency fiber laser at 1083 nm.

    PubMed

    Zhang, Yuanfei; Yang, Changsheng; Li, Can; Feng, Zhouming; Xu, Shanhui; Deng, Huaqiu; Yang, Zhongmin

    2016-02-22

    A linearly frequency-modulated, actively Q-switched, single-frequency ring fiber laser based on injection seeding from an ultra-short cavity is demonstrated at 1083 nm. A piezoelectric transducer is employed to obtain linearly frequency-modulating performance and over 1.05 GHz frequency-tuning range is achieved with a modulating frequency reaching tens of kilohertz. A maximum peak power of the stable output pulse is over 3.83 W during frequency-modulating process. This type of pulsed fiber laser provides a promising candidate for coherent LIDAR in the measurement of thermosphere. PMID:26906980

  2. Evidence for high-efficiency laser-heated hohlraum performance at 527 nm.

    PubMed

    Stevenson, R M; Oades, K; Thomas, B R; Schneider, M; Slark, G E; Suter, L J; Kauffman, R; Hinkel, D; Miller, M C

    2005-02-11

    A series of experiments conducted on the HELEN laser system [M. J. Norman, Appl. Opt.4120023497], into thermal x-ray generation from hohlraum targets using 527 nm (2omega) wavelength laser light, has shown that it is possible to exceed radiation temperatures previously thought limited by high levels of superthermal or hot electron production or stimulated backscatter. This Letter questions whether the assumptions traditionally applied to hohlraum design with respect to hot plasma filling and the use of 2omega light are too conservative. PMID:15783658

  3. Laser ablation at 337 nm of nitrocellulose and nylon sensitized with organic dopants

    NASA Astrophysics Data System (ADS)

    Skordoulis, Constantine D.; Kosmidis, Constantine E.

    1993-05-01

    The laser induced ablative decomposition of nitrocellulose and nylon sensitized with organic dopants (Stilbene 420, Coumarin 120, and Rhodamine 6G) has been studied. Ablation with a low power nitrogen laser is hereby reported for the first time. With the addition of dyes strongly absorbing at 337 nm the photoetching rate of the pure materials can be significantly increased. A two step photochemical mechanism considering the decomposition of the polymers from excited electronic states and the energy transfer process from the dye to the polymer are discussed.

  4. Simultaneous dual-wavelength oscillation at 1116 and 1123 nm of Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Bo, Y.; Xu, J. L.; Tian, C. Y.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2011-09-01

    We report on to our knowledge the first time a diode-side-pumped simultaneous dual-wavelength Nd:YAG laser at 1116 and 1123 nm. By inserting an etalon to balance the gain and loss, a stable dual-wavelength oscillation is acquired. The numerical simulations for wavelength tuning are discussed by principles of laser threshold and Fabry-Perot etalon. Under the pump power of 250 W, a total output power of 23 W is obtained. Meanwhile, the two components have approximately equal intensities. The beam quality of M 2 factor was measured to be 7.52.

  5. Highly reliable high-efficiency wavelength-stabilized 885 nm diode laser bars

    NASA Astrophysics Data System (ADS)

    Leisher, Paul; Bao, Ling; Huang, Hua; Wang, Jun; DeVito, Mark; Dong, Weimin; Grimshaw, Mike; Balsley, David; Martinsen, Rob; DeFranza, Mark; Patterson, Steve

    2009-05-01

    We report on the progress of highly-reliable, high-efficiency 885-nm diode laser bar arrays. Conduction-cooled hardsoldered bars rated to 60W and 57% conversion efficiency demonstrate >30,000 device hours under 1-sec on, 1-sec off hard pulse conditions failure-free. Microchannel-cooled bars rated to 100W and 62% efficiency demonstrate >100,000 accelerated device hours failure-free. Integrated volume Bragg grating fast axis lenses provide wavelength stabilization at low cost. Vertically stacked arrays (seven bars each) of such configuration are demonstrated with a 0.8 nm FWHM spectral width and rated to 700W, 53% conversion efficiency.

  6. Sub-500-nm patterning of glass by nanosecond KrF excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Bekesi, J.; Meinertz, J.; Simon, P.; Ihlemann, J.

    2013-01-01

    The surface of flint glass of type F2 is patterned by nanosecond KrF excimer laser ablation. Strong UV absorption provides a comparatively low ablation threshold and precise ablation contours. By using a two-grating interferometer, periodic surface patterns with 330 nm period and 100 nm modulation depth are obtained. This method enables the fabrication of 7 mm×13 mm wide grating areas with perfectly aligned grooves without the need of high-precision sample positioning. By double exposure, crossed gratings with adjustable depths in the two orthogonal directions can be generated.

  7. Electronically tunable thulium-holmium mode-locked fiber laser for the 1700-1800 nm wavelength band.

    PubMed

    Noronen, Teppo; Okhotnikov, Oleg; Gumenyuk, Regina

    2016-06-27

    We demonstrate a widely tunable, mode-locked fiber laser capable of producing sub-picosecond pulses between 1705 and 1805 nm. The 100 nm tuning range is achieved by using intracavity acousto-optic tunable filter. The laser delivers highly stable pulses via self-starting hybrid mode-locking triggered by frequency-shifting and nonlinear polarization evolution. PMID:27410623

  8. Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency

    NASA Astrophysics Data System (ADS)

    Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.

    2016-03-01

    The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (<1 nm), combined with wavelength thermal stabilization (0.07 𝑛𝑚 • °𝐶-1), provided by a uniform distributed feedback grating (DFB) introduced by etching and re-growth process techniques, is achievable in high power diode lasers using optical feedback. This paper reports on the development of the diode laser structure and the process techniques required to write the gratings taking into account of the thermal dissipation and optical performances. Performances are particularly determined in terms of experimental electro-optical characterizations. One of the main objectives is to determine the thermal resistance of the complete assembly to ensure the mastering of the diode laser temperature for operating condition. The classical approach to determine junction temperature is based on the infrared thermal camera, the spectral measurement and the pulse electrical method. In our case, we base our measurement on the spectral measurement but this approach is not well adapted to the high power diodes laser studied. We develop a new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high

  9. Resonance transition radiation X-ray laser

    NASA Technical Reports Server (NTRS)

    Reid, Max B.; Piestrup, Melvin A.

    1991-01-01

    A free electron laser is proposed using a periodic dielectric and helical magnetic field. Periodic synchronism between the electrons and the optical wave is obtained at the period of the dielectric and not at the period of the helical magnetic field. The synchronism condition and the gain of the new device are derived. The effects on the gain from dephasing and beam expansion due to elastic scattering of the electrons in the periodic medium are included in the gain calculation. Examples of the resonance transition radiation laser and klystron are given. Operation at photon energies between 2.5 and 3.5 keV with net gain up to 12 percent is feasible using high electron-beam energies of 3 and 5 GeV. Moderate (300-MeV) beam energy allows operation between 80 to 110 eV with up to 57 percent net gain using a klystron design. In both cases, rapid foil heating may limit operation to a single electron-beam pulse.

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

    NASA Astrophysics Data System (ADS)

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

    2000-05-01

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

  11. Comparison of four lasers (λ = 650, 808, 980, and 1075 nm) for noninvasive creation of deep subsurface lesions in tissue

    NASA Astrophysics Data System (ADS)

    Chang, Chun-Hung; Wilson, Christopher R.; Fried, Nathaniel M.

    2015-07-01

    Lasers have been used in combination with applied cooling methods to preserve superficial skin layers (100's μm's) during cosmetic surgery. Preservation of a thicker tissue surface layer (millimeters) may also allow development of other noninvasive laser procedures. We are exploring noninvasive therapeutic laser applications in urology (e.g. laser vasectomy and laser treatment of female stress urinary incontinence), which require surface tissue preservation on the millimeter scale. In this preliminary study, four lasers were compared for noninvasive creation of deep subsurface thermal lesions. Laser energy from three diode lasers (650, 808, and 980 nm) and a Ytterbium fiber laser (1075 nm) was delivered through a custom built, side-firing, laser probe with integrated cooling. An alcohol-based solution at -5 °C was circulated through a flow cell, cooling a sapphire window, which in turn cooled the tissue surface. The probe was placed in contact with porcine liver tissue, ex vivo, kept hydrated in saline and maintained at ~ 35 °C. Incident laser power was 4.2 W, spot diameter was 5.3 mm, and treatment time was 60 s. The optimal laser wavelength tested for creation of deep subsurface thermal lesions during contact cooling of tissues was 1075 nm, which preserved a surface layer of ~ 2 mm. The Ytterbium fiber laser provides a compact, low maintenance, and high power alternative laser source to the Neodymium:YAG laser for noninvasive thermal therapy.

  12. Lower Energy Endovenous Laser Ablation of the Great Saphenous Vein with 980 nm Diode Laser in Continuous Mode

    SciTech Connect

    Kim, Hyun S. Nwankwo, Ikechi J.; Hong, Kelvin; McElgunn, Patrick S.J.

    2006-02-15

    Purpose. To assess clinical outcomes, complication rates, and unit energy applied using 980 nm diode endovenous laser treatment at 11 watts for symptomatic great saphenous vein (GSV) incompetence and reflux disease. Methods. Thirty-four consecutive ablation therapies with a 980 nm diode endovenous laser at 11 watts were studied. The diagnosis of GSV incompetence with reflux was made by clinical evaluation and duplex Doppler examinations. The treated GSVs had a mean diameter of 1.19 cm (range 0.5-2.2 cm). The patients were followed with clinical evaluation and color flow duplex studies up to 18.5 months (mean 12.19 months {+-} 4.18). Results. Using 980 nm diode endovenous laser ablation in continuous mode, 100% technical success was noted. The mean length of GSVs treated was 33.82 cm (range 15-45 cm). The mean energy applied during the treatment was 1,155.81 joules (J) {+-} 239.50 (range 545.40-1620 J) for a mean treatment duration of 90.77 sec {+-} 21.77. The average laser fiber withdrawal speed was 0.35 cm/sec {+-} 0.054. The mean energy applied per length of GSV was 35.16 J/cm {+-} 8.43. Energy fluence, calculated separately for each patient, averaged 9.82 J/cm{sup 2} {+-} 4.97. At up to 18.5 months follow-up (mean 12.19 months), 0% recanalization was noted; 92% clinical improvement was achieved. There was no major complication. Minor complications included 1 patient with hematoma at the percutaneous venotomy site, 1 patient with thrombophlebitis on superficial tributary varices of the treated GSV, 24% ecchymoses, and 32% self-limiting hypersensitivity/tenderness/'pulling' sensation along the treatment area. One patient developed temporary paresthesia. Four endovenous laser ablation treatments (12%) were followed by adjunctive sclerotherapies for improved cosmetic results. Conclusion. Endovenous laser ablation treatment of GSV using a 980 nm diode laser at 11 watts in continuous mode appears safe and effective. Mean energy applied per treated GSV length of 35

  13. Comparative laser Doppler measurement on tooth pulp blood flow at 632 and 750 nm

    NASA Astrophysics Data System (ADS)

    Oberg, P. Ake; Pettersson, Hans; Rohman, Hakan

    1993-12-01

    Laser-Doppler flowmetry has been used for the assessment of pulp blood flow in health and disease. General purpose laser Doppler instruments working at the Helium-Neon (632,8 nm) as well as IR (750 - 810 nm) wavelengths have been used in this application. Specially designed handheld equipment has also been used to assess blood supply to the tooth. A considerable difference in the measurement results have been noticed when using different wavelengths and probe designs. In this study some of the problems related to the use of various wavelengths and probe designs are studied in human teeth and in a physical model of a tooth. Our results support the early observation that measurements at different wavelengths and with different probe designs cannot be directly compared.

  14. Experience in the 532-nm green laser treatment of cutaneous angiodysplasias using an automatic delivery system

    NASA Astrophysics Data System (ADS)

    Mordon, Serge R.; Suchet-Lopez, Marie A.; Rotteleur, Guy; Brunetaud, Jean Marc

    1992-06-01

    Cutaneous angiodysplasias are currently treated by Argon, CW-Dye or Pulsed Dye Lasers. Green light at 532 nm is highly specific for hemoglobin-laden vessels. Therefore, this wavelength was evaluated on different cutaneous angiodysplasias. One hundred thirty-five (135) patients with either port wine stains (94) or facial telangiectasia (41) were treated with a 532 nm laser coupled to an automatic delivery system. Treatments were performed using the minimal blanching technique. The average fluence was 17 J/cm-2 for port wine stains and 15 J/cm-2 for facial telangiectasia. Pathologic scars were not reported for any patient. Sixty percent (60%) of the patients with port wine stains achieved good or excellent results after a 12-month period of observations. Ninety percent (90%) of the patients with facial telangiectasia achieved good or excellent results after a 12-month period of observation.

  15. Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm.

    PubMed

    Bek, Roman; Baumgärtner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbäck, Thomas; Jetter, Michael; Michler, Peter

    2015-07-27

    We present a passively mode-locked semiconductor disk laser (SDL) emitting at 650nm with intra-cavity second harmonic generation to the ultraviolet (UV) spectral range. Both the gain and the absorber structure contain InP quantum dots (QDs) as active material. In a v-shaped cavity using the semiconductor samples as end mirrors, a beta barium borate (BBO) crystal is placed in front of the semiconductor saturable absorber mirror (SESAM) for pulsed UV laser emission in one of the two outcoupled beams. Autocorrelation (AC) measurements at the fundamental wavelength reveal a FWHM pulse duration of 1.22ps. With a repetition frequency of 836MHz, the average output power is 10mW per beam for the red emission and 0.5mW at 325nm. PMID:26367654

  16. Electron microscopic study on black pig skin irradiated with pulsed dye laser (504 nm)

    NASA Astrophysics Data System (ADS)

    Yasuda, Yukio; Tan, Oon T.; Kurban, Amal K.; Tsukada, Sadao

    1991-06-01

    Selective damage of epidermal pigment cells induced by 504 nm pulsed dye laser at different pulse durations and fluence on black pig skin was examined electron microscopically. Epidermal melanosomes were satisfactorily disrupted at shorter pulse duration (100 ns). Epidermal blister formation and necrosis were seen at 2 days postirradiation, and reepithelization was evident at 7 days postirradiation in all specimens. Repigmentation was evident 21 to 56 days after irradiation. Histological pigmentary incontinence was evident at 2 days and persisted until 56 days postirradiation. This phenomenon was observed more frequently in skin exposed to longer pulse duration and at low fluences. Optimal parameters required to induce epidermal melanosome disruption using the 504 nm pulsed dye laser will be discussed.

  17. Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

    SciTech Connect

    Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C.

    2013-04-22

    There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

  18. Highly efficient continuous-wave Nd:YAG ceramic lasers at 946 nm

    NASA Astrophysics Data System (ADS)

    Zhu, H. Y.; Xu, C. W.; Zhang, J.; Tang, D. Y.; Luo, D. W.; Duan, Y. M.

    2013-07-01

    Highly efficient CW operation of diode-end-pumped Nd:YAG ceramic lasers at 946 nm is experimentally demonstrated. When a 5 mm long in-house fabricated Nd:YAG ceramic was used as the gain medium, a maximum output power of 10.5 W was obtained under an incident pump power of 35 W, corresponding to an optical conversion efficiency of 30%, while, when a 3 mm long ceramic sample was used, a maximum output power of 8.7 W was generated with a slope efficiency of 65% with respect to the absorbed pump power. Both the optical conversion efficiency and slope efficiency are the highest results reported so far for the diode-pumped 946 nm lasers.

  19. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    NASA Astrophysics Data System (ADS)

    Leich, M.; Jäger, M.; Grimm, S.; Hoh, D.; Jetschke, S.; Becker, M.; Hartung, A.; Bartelt, H.

    2014-04-01

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power.

  20. Single Frequency, Pulsed Laser Diode Transmitter for Dial Water Vapor Measurements at 935nm

    NASA Technical Reports Server (NTRS)

    Switzer, Gregg W.; Cornwell, Donald M., Jr.; Krainak, Michael A.; Abshire, James B.; Rall, Johnathan A. R.

    1998-01-01

    We report a tunable, single frequency, narrow linewidth, pulsed laser diode transmitter at 935.68nm for remote sensing of atmospheric water vapor. The transmitter consists of a CW, tunable, external cavity diode laser whose output is amplified 2OdB using a tapered diode amplifier. The output is pulsed for range resolved DIAL lidar by pulsing the drive current to the diode amplifier at 4kHz with a .5% duty cycle. The output from the transmitter is 36OnJ/pulse and is single spatial mode. It maintains a linewidth of less than 25MHz as its wavelength is tuned across the water vapor absorption line at 935.68nm. The transmitter design and its use in a water vapor measurement will be discussed.

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

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

    1986-01-01

    Raman conversion efficiency and line broadening are reported for Stokes operation at 720 and 940 nm, with hydrogen and deuterium as the Raman source, and using an Nd:YAG pumped Quanta-Ray PDL-2 dye laser. The dye laser linewidth is 0.2/cm (FWHM) with the grating alone as an intracavity element, and the conversion efficiency at 400 psi was found to be 40 and 20 percent for outputs of 720 and 940 nm, respectively. Pressure broadening coefficients of (9.2 + or - 0.9) x 10 to the -5th per cm/psi for hydrogen, and 7.7 x 10 to the -5th per cm/psi for deuterium, were obtained in good agreement with previous results. The linewidth at the first Stokes wavelength was shown to be determined by pressure broadening in the Raman medium.

  2. Diode-pumped 1028 nm Ytterbium-doped fiber laser with near 90% slope efficiency

    NASA Astrophysics Data System (ADS)

    Harun, S. W.; Paul, M. C.; Moghaddam, M. R. A.; Das, S.; Sen, R.; Dhar, A.; Pal, M.; Bhadra, S. K.; Ahmad, H.

    2010-03-01

    Highly efficient laser action from an Ytterbium-doped fiber (YDF) is demonstrated using a fiber Bragg grating (FBG) in conjunction with a 4% Fresnel reflection at room temperature. The YDF used is drawn from Yb2O3-doped preform, fabricated through deposition of porous layer of composition SiO2-GeO2 by the MCVD process in conjunction with a solution doping technique. The fabricated YDF has a core composition of 0.2 wt % of Yb2O3, 1.8 wt % of Al2O3 and 23 wt % of GeO2 with a pump absorption of 9.0 dB/m. The fiber laser operates at wavelength of 1028 nm with a slope efficiency of 88% with respect to the launched 976 nm pump power using the YDF length of 7 m.

  3. Photobiomodulation with 660-nm and 780-nm laser on activated J774 macrophage-like cells: Effect on M1 inflammatory markers.

    PubMed

    Fernandes, Kristianne Porta Santos; Souza, Nadhia Helena Costa; Mesquita-Ferrari, Raquel Agnelli; Silva, Daniela de Fatima Teixeira da; Rocha, Lilia Alves; Alves, Agnelo Neves; Sousa, Kaline de Brito; Bussadori, Sandra Kalil; Hamblin, Michael R; Nunes, Fábio Daumas

    2015-12-01

    M1 profile macrophages exert a major influence on initial tissue repair process. Few days after the occurrence of injury, macrophages in the injured region exhibit a M2 profile, attenuate the effects of the M1 population, and stimulate the reconstruction of the damaged tissue. The different effects of macrophages in the healing process suggest that these cells could be the target of therapeutic interventions. Photobiomodulation has been used to accelerate tissue repair, but little is known regarding its effect on macrophages. In the present study, J774 macrophages were activated to simulate the M1 profile and irradiated with two different sets of laser parameters (780 nm, 70 mW, 2.6J/cm(2), 1.5s and 660 nm, 15 mW, 7.5 J/cm(2), 20s). IL-6, TNF-α, iNOS and COX-2 gene and protein expression were analyzed by RT-qPCR and ELISA. Both lasers were able to reduce TNF-α and iNOS expression, and TNF-α and COX-2 production, although the parameters used for 780 nm laser provided an additional decrease. 660 nm laser parameters resulted in an up-regulation of IL-6 expression and production. These findings imply a distinct, time-dependent modulation by the two different sets of laser parameters, suggesting that the best modulation may involve more than one combination of parameters. PMID:26519828

  4. [A Methane Detection System Using Distributed Feedback Laser at 1 654 nm].

    PubMed

    Li, Bin; Liu, Hui-fang; He, Qi-xin; Zhai, Bing; Pan, Jiao-qing; Zheng, Chuan-tao; Wang, Yi-ding

    2016-01-01

    A methane (CH4) detection system based on tunable diode laser absorption spectroscopy (TDLAS) technique was experimentally demonstrated. A distributed feedback (DFB) laser around 1 654 nm, an open reflective sensing probe and two InGaAs photodiodes were adopted in the system. The electrical part of the system mainly includes the laser temperature control & modulation module and the orthogonal lock-in amplifier module. Temperature and spectrum tests on the DFB laser indicate that, the laser temperature fluctuation can be limited to the range of -0.02-0.02 degrees C, the laser's emitting wavelength varies linearly with the temperature and injection current, and also good operation stability of the laser was observed through experiments. Under a constant working temperature, the center wavelength of the laser is varied linearly by adjusting the driving current. Meanwhile, a 5 kHz sine wave signal and a 10 Hz saw wave signal were provided by the driving circuit for the harmonic extraction purpose. The developed orthogonal lock-in amplifier can extract the If and 2f harmonic signals with the extraction error of 3.55% and 5% respectively. By using the open optical probe, the effective optical pass length was doubled to 40 cm. Gas detection experiment was performed to derive the relation between the harmonic amplitude and the gas concentration. As the concentration increases from 1% to 5%, the amplitudes of the 1f harmonic and the 2f harmonic signal were obtained, and good linear ration between the concentration and the amplitude ratio was observed, which proves the normal function of the developed detection system. This system is capable to detect other trace gases by using relevant DFB lasers. PMID:27228733

  5. Sub-MHz linewidth of 633 nm diode lasers with internal surface DBR gratings

    NASA Astrophysics Data System (ADS)

    Feise, D.; Blume, G.; Pohl, J.; Sumpf, B.; Thiem, H.; Reggentin, M.; Wiedmann, J.; Paschke, K.

    2013-03-01

    Red-emitting diode lasers having a large coherence length with a tunable wavelength and a narrow spectral linewidth with an emission power in the 10 mW range are sought for a variety of techniques in applications such as spectroscopy, interferometry and holography. Currently, helium-neon lasers or diode lasers with external wavelength stabilization are widely used for these applications. By integrating a wavelength selective element into the ridge waveguide (RW) of the diode laser chip itself a high degree of miniaturization and stability can be reached. To this end, we have developed RW lasers with deeply etched surface distributed Bragg reflector (DBR) gratings in order to achieve a high-yield, singleepitaxy manufacturing process. These DBR lasers consist of a 1.5 mm RW gain section and a 500 μm grating section, which has a reflectivity of about 60%. The facets of the lasers were coated to achieve a reflectivity of 30% at the front and smaller than 0.1% at the rear facet. The diode lasers achieve an optical output power of 20 mW at an injection current of 150 mA and a heat-sink temperature of 15°C at a wavelength of 633 nm. The DBR enables single longitudinal mode operation over a wide range of operation conditions. Self-delayed heterodyne measurements were performed to measure the emission linewidth of these lasers using a 1 km long fiber, which gives a spectral resolution of about 100 kHz. A linewidth of less than 1 MHz was obtained. In reliability tests at 14 mW a lifetime of more than 1,700 h could be demonstrated, dedicating these devices to the above mentioned applications.

  6. Experimental study on 785 nm femtosecond laser ablation of sapphire in air

    NASA Astrophysics Data System (ADS)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2015-06-01

    Changes in surface morphology and ablation rate induced on sapphire were investigated after interaction with femtosecond laser pulses in air at variable fluence (2 to 77 J cm-2) and repetition rate (10 to 1000 Hz). Multiple laser pulses at a wavelength of 785 nm and pulse width of 130 fs were fired at the surface of sapphire to produce craters whose depth, size and morphology were evaluated using optical and scanning electron microscopy. Ablation rate was found to depend on laser fluence, number of laser pulses and repetition rate. A rapid increase in ablation rate with fluence was observed for fluences lower than 5.9 J cm-2, followed by a slow increase up to fluence of 40.7 J cm-2. A drop in ablation rate occurred at fluence greater than 40.7 J cm-2. Craters produced at high repetition rate (1000 Hz) at fluence of 11.8 J cm-2 were deeper than those produced at low repetition rate (10 Hz) during the first 40 to 50 pulses. The situation was reversed for craters produced by greater than 50 laser pulses. The drop in ablation rate observed at high fluence and repetition rate can be attributed to attenuation of the laser energy due to plasma and particle shielding that result from interactions with the laser-generated particles that cannot be completely removed from the ablated crater. Defocusing effects associated with the non-equilibrium ionization of air which causes a divergence to the laser beam and consequently a reduction in the laser intensity at the sample surface can be another reason for the observed drop in the ablation rate at high fluence.

  7. Rayleigh rejection filters for 193-nm ArF laser Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.

    1993-01-01

    Selected organic absorbers and their solvents are evaluated as spectral filters for the rejection of 193-nm Rayleigh light associated with the use of an ArF excimer laser for Raman spectroscopy. A simply constructed filter cell filled with 0.5 percent acetone in water and an optical path of 7 mm is shown effectively to eliminate stray Rayleigh light underlying the Raman spectrum from air while transmitting 60 percent of the Raman light scattered by O2.

  8. 910nm femtosecond Nd-doped fiber laser for in vivo two-photon microscopic imaging.

    PubMed

    Chen, Bingying; Jiang, Tongxiao; Zong, Weijian; Chen, Liangyi; Zhang, Zhigang; Wang, Aimin

    2016-07-25

    Pre-chirp technique was used in an Nd-doped fiber amplifier to optimize high-quality 910 nm pulses with the pulses width of 114 fs and pulse energy of 4.4 nJ. The in vivo zebrafish imaging results from our totally home-made microscopy proves our femtosecond Nd fiber laser an ideal source in two-photon microscopic imaging. PMID:27464109

  9. Studies on 405nm blue-violet diode laser with external grating cavity

    NASA Astrophysics Data System (ADS)

    Li, Bin; Gao, Jun; Zhao, Jun; Yu, Anlan; Luo, Shiwen; Xiong, Dongsheng; Wang, Xinbing; Zuo, Duluo

    2016-03-01

    Spectroscopy applications of free-running laser diodes (LD) are greatly restricted as its broad band spectral emission. And the power of a single blue-violet LD is around several hundred milliwatts by far, it is of great importance to obtain stable and narrow line-width laser diodes with high efficiency. In this paper, a high efficiency external cavity diode laser (ECDL) with high output power and narrow band emission at 405 nm is presented. The ECDL is based on a commercially available LD with nominal output power of 110 mW at an injection current of 100 mA. The spectral width of the free-running LD is about 1 nm (FWHM). A reflective holographic grating which is installed on a home-made compact adjustable stage is utilized for optical feedback in Littrow configuration. In this configuration, narrow line-width operation is realized and the effects of grating groove density as well as the groove direction related to the beam polarization on the performances of the ECDL are experimentally investigated. In the case of grating with groove density of 3600 g/mm, the threshold is reduced from 21 mA to 18.3 mA or 15.6 mA and the tuning range is 3.95 nm or 6.01 nm respectively when the grating is orientated in TE or TM polarization. In addition, an output beam with a line-width of 30 pm and output power of 92.7 mW is achieved in TE polarization. With these narrow line-width and high efficiency, the ECDL is capable to serve as a light source for spectroscopy application such as Raman scattering and laser induced fluorescence.

  10. Development of high coherence, 200mW, 193nm solid-state laser at 6 kHz

    NASA Astrophysics Data System (ADS)

    Nakazato, T.; Tsuboi, M.; Onose, T.; Tanaka, Y.; Sarukura, N.; Ito, S.; Kakizaki, K.; Watanabe, S.

    2015-02-01

    The high coherent, high power 193-nm ArF lasers are useful for interference lithography and microprosessing applications. In order to achieve high coherence ArF lasers, we have been developing a high coherence 193 nm solid state laser for the seeding to a high power ArF laser. We used the sum frequency mixing of the fourth harmonic (FH) of a 904-nm Ti:sapphire laser with a Nd:YVO4 laser (1342 nm) to generate 193-nm light. The laser system consists of a single-mode Ti:sapphire oscillator seeded by a 904-nm external cavity laser diode, a Pockels cell, a 6-pass amplifier, a 4-pass amplifier, a 2-pass amplifier and a wavelength conversion stage. The required repetition rate of 6 kHz corresponding to the ArF laser, along with a low gain at 904 nm induces serious thermal lens effects; extremely short focal lengths of the order of cm and bi-foci in the vertical and horizontal directions. From the analysis of thermal lens depending on pump intensity, we successfully compensated the thermal lens by dividing a 527-nm pump power with 15, 25 and 28 W to 3-stage amplifiers with even passes, resulting in the output power above 10W with a nearly diffraction limited beam. This 904-nm output was converted to 3.8 W in the second harmonic by LBO, 0.5 W in FH by BBO sequentially. Finally the output power of 230 mW was obtained at 193 nm by mixing the FH with a 1342-nm light in CLBO.

  11. Preclinical Assessment of a 980-nm Diode Laser Ablation System in a Large Animal Tumor Model

    PubMed Central

    Ahrar, Kamran; Gowda, Ashok; Javadi, Sanaz; Borne, Agatha; Fox, Matthew; McNichols, Roger; Ahrar, Judy U.; Stephens, Clifton; Stafford, R. Jason

    2010-01-01

    Purpose To characterize the performance of a 980-nm diode laser ablation system in an in vivo tumor model. Materials and Methods This study was approved by the Institutional Animal Care and Use Committee. The ablation system consisted of a 15-W, 980-nm diode laser, flexible diffusing tipped fiber optic, and 17-gauge internally cooled catheter. Ten immunosuppressed dogs were inoculated subcutaneously with canine transmissible venereal tumor fragments in eight dorsal locations. Laser ablations were performed at 79 sites where inoculations were successful (99%) using powers of 10 W, 12.5 W, and 15 W, with exposure times between 60 and 180 seconds. In 20 cases, multiple overlapping ablations were performed. After the dogs were euthanized, the tumors were harvested, sectioned along the applicator track, measured and photographed. Measurements of ablation zone were performed on gross specimen. Histopathology and viability staining was performed using hematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide hydrogen (NADH) staining. Results Gross pathology confirmed well-circumscribed ablation zone with sharp boundaries between thermally ablated tumor in the center surrounded by viable tumor tissue. When a single applicator was used, the greatest ablation diameters ranged from 12 mm at the lowest dose (10 W, 60 sec) to 26 mm at the highest dose (15 W, 180 sec). Multiple applicators created ablation zones of up to 42 mm in greatest diameter (with the lasers operating at 15 W for 120 sec). Conclusions The new 980-nm diode laser and internally cooled applicator effectively creates large ellipsoid thermal ablations in less than 3 minutes. PMID:20346883

  12. Etching of fused silica and glass with excimer laser at 351 nm

    NASA Astrophysics Data System (ADS)

    Zimmer, K.; Braun, A.; Böhme, R.

    2003-03-01

    The etching of solid surfaces at the interface to liquids is a new promising method for micro-machining of transparent materials. To extend the method to additional materials the pulsed radiation of a XeF-excimer laser (351 nm) was used for etching different types of glass (Corning Inc.: Pyrex, 7059 and Schott Group: D263, AF45) and fused silica for comparison. The etch rates of the investigated materials increase almost linear at low laser fluences. Threshold fluences for glass as low as 0.5 J/cm 2 and etch rates from 6 to 10 nm per pulse at 1 J/cm 2 have been determined. The etch rate and the threshold fluence depend also on the used liquid, consisting of a solvent (acetone, toluene) and a certain concentration of dissolved pyrene, but only little on the glass type. Due to the low etch rate typically very smooth surfaces are achieved. The surface roughness measured by AFM on Corning 7059-glass at an etch depth of 3.7 μm is as low as 4 nm. Contrary to the other glasses the surface roughness of Pyrex is much higher and dominated by typical arbitrary etch pits with micron dimensions. Comparing the etching of fused silica at a wavelength of 248 and 351 nm the used solution influences both the etch threshold and the etch rate. In accordance to earlier investigations at 248 nm also XeF-laser etching at the interface to an absorbing liquid results in a good surface quality, well defined patterns and almost no debris deposition. Thus, this technique is a good candidate for precise micro-machining applications.

  13. Preliminary characterisation of new glass reference materials (GSA-1G, GSC-1G, GSD-1G and GSE-1G) by laser ablation-inductively coupled plasma-mass spectrometry using 193 nm, 213 nm and 266 nm wavelengths

    USGS Publications Warehouse

    Guillong, M.; Hametner, K.; Reusser, E.; Wilson, S.A.; Gunther, D.

    2005-01-01

    New glass reference materials GSA-1G, GSC-1G, GSD-1G and GSE-1G have been characterised using a prototype solid state laser ablation system capable of producing wavelengths of 193 nm, 213 nm and 266 nm. This system allowed comparison of the effects of different laser wavelengths under nearly identical ablation and ICP operating conditions. The wavelengths 213 nm and 266 nm were also used at higher energy densities to evaluate the influence of energy density on quantitative analysis. In addition, the glass reference materials were analysed using commercially available 266 nm Nd:YAG and 193 nm ArF excimer lasers. Laser ablation analysis was carried out using both single spot and scanning mode ablation. Using laser ablation ICP-MS, concentrations of fifty-eight elements were determined with external calibration to the NIST SRM 610 glass reference material. Instead of applying the more common internal standardisation procedure, the total concentration of all element oxide concentrations was normalised to 100%. Major element concentrations were compared with those determined by electron microprobe. In addition to NIST SRM 610 for external calibration, USGS BCR-2G was used as a more closely matrix-matched reference material in order to compare the effect of matrix-matched and non matrix-matched calibration on quantitative analysis. The results show that the various laser wavelengths and energy densities applied produced similar results, with the exception of scanning mode ablation at 266 nm without matrix-matched calibration where deviations up to 60% from the average were found. However, results acquired using a scanning mode with a matrix-matched calibration agreed with results obtained by spot analysis. The increased abundance of large particles produced when using a scanning ablation mode with NIST SRM 610, is responsible for elemental fractionation effects caused by incomplete vaporisation of large particles in the ICP.

  14. Performance comparison of nonlinear crystals for frequency doubling of an 894nm Cs vapor laser

    NASA Astrophysics Data System (ADS)

    Zhdanov, B. V.; Shaffer, M. K.; Lu, Y.; Naumann, B.; Genda, T.; Knize, R. J.

    2010-11-01

    An examination of the efficiencies of three commonly used nonlinear crystals (PPKTP, LBO, and BiBO) when generating second harmonic of a Cesium laser is presented. The experiment investigates both the intracavity and single pass second harmonic generation of 895 nm Cs laser light when operating in quasi-CW and in CW modes and pumped by several watts. A degradation of the conversion efficiencies for each crystal was observed when high fundamental powers or a high duty cycle of the pump were used. For a Cs laser operating at 894nm, PPKTP is found to be the optimal crystal for intracavity SHG in both pulsed and CW modes when operating at SHG powers of several watts. At higher powers, however, the increased absorption coefficient of PPKTP at 447nm, compared to that of BiBO or LBO, may become significant to where another crystal will be more appropriate for this application. Maximum blue light power obtained with PPKTP crystal was about 1.5W in CW mode and 2.5W in QCW.

  15. 980 nm diode lasers in oral and facial practice: current state of the science and art

    PubMed Central

    DESIATE, Apollonia; CANTORE, Stefania; TULLO, Domenica; PROFETA, Giovanni; GRASSI, Felice Roberto; BALLINI, Andrea

    2009-01-01

    Aim: To evaluate the safety and efficacy of a 980nm diode laser for the treatment of benign facial pigmented and vascular lesions, and in oral surgery. Materials and Methods: 20 patients were treated with a 980 nm diode laser. Oral surgery: 5 patients (5 upper and lower frenulectomy). Fluence levels were 5-15 J/cm2; pulse lengths were 20-60 ms; spot size was 1 mm. Vascular lesions: 10 patients (5 small angiomas, 5 telangiectases). Fluences were 6-10 J/cm2; pulse lengths were 10-50 ms; spot size was 2 mm. In all cases the areas surrounding the lesions were cooled. Pigmented lesions: 5 patients (5 keratoses). All the lesions were evaluated by dermatoscopy before the treatment. Fluence levels were 7-15 J/cm2; pulse lengths were 20-50 ms; spot size was 1 mm. All the patients were followed at 1, 4 and 8 weeks after the procedure. Results: Healing in oral surgery was within 10 days. The melanoses healed completely within four weeks. All the vascular lesions healed after 15 days without any residual scarring. Conclusions: The end results for the use of the 980 nm diode laser in oral and facial surgery appears to be justified on the grounds of efficacy and safety of the device, and good degree of acceptance by the patients, without compromising their health and function. PMID:19960121

  16. High power resonantly diode-pumped σ-configuration Er3+:YVO4 laser at 1593.5 nm

    NASA Astrophysics Data System (ADS)

    Ter-Gabrielyan, N.; Fromzel, V.; Lukasiewicz, T.; Ryba-Romanowski, W.; Dubinskii, M.

    2011-07-01

    Laser operation of an eyesafe 1593.5-nm laser based on Er3+-doped yttrium orthovanadate single crystal resonantly-pumped by a spectrally-narrowed InGaAsP/InP diode bar stack is demonstrated for the first time. Cryogenically-cooled Er3+:YVO4 laser pumped at 1534 nm performed with maximum slope efficiency of ~ 70% and maximum quasi-continuous-wave (Q-CW) power of 59.8 W.

  17. Laser-induced damage morphology in fused silica at 1064 nm in the nanosecond regime

    NASA Astrophysics Data System (ADS)

    Chambonneau, Maxime; Diaz, Romain; Duchateau, Guillaume; Grua, Pierre; Natoli, Jean-Yves; Rullier, Jean-Luc; Lamaignère, Laurent

    2014-10-01

    The morphology of laser-induced damage sites at the exit surface of fused silica is tightly correlated to the mode composition of the nanosecond laser pulses at 1064 nm. In the single longitudinal mode (SLM) configuration, a molten and fractured central zone is surrounded by a funnel-shaped surface modification. Ring patterns surround the damage sites when these are initiated by multiple longitudinal modes (MLM) laser pulses. In this last mode configuration, the pulses temporal profiles as well as the damage ring patterns differ from pulse to pulse. The appearance chronology of the rings is found to be closely related to the temporal shape of the laser pulses. This supports that the damage morphology originates from the coupling of a laser-supported detonation wave propagating in air with an ablation mechanism in silica. In our experiments, the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theory.

  18. Nitrogen laser irradiation (337 nm) causes temporary inactivation of clinical isolates of Mycobacterium tuberculosis.

    PubMed

    Dube, Alok; Jayasankar, K; Prabakaran, L; Kumar, V; Gupta, P K

    2004-01-01

    We have investigated the effect of nitrogen laser irradiation (337 nm) on viability of clinical isolates of Mycobacterium tuberculosis. Bacteria were exposed to a nitrogen laser (average power 2.0 mW) in vitro at power density of 70 +/- 0.7 W/m2 for 0-30 min, and the cell viability was determined by luciferase reporter phage (LRP) assay. Immediately after laser exposure, all the clinical isolates investigated showed a dose-dependent decrease in cell viability. However, when the laser-exposed isolates were incubated in broth medium for 3 days, most of these showed significant recovery from laser-induced damage. Addition of 5.0 microg/ml acriflavine (a DNA repair inhibitor) in the incubation medium had no significant effect on recovery. This suggests that DNA damage may not be involved in the cell inactivation. Electron paramagnetic resonance (EPR) studies using 5-doxyl strearic acid (5-DS) as a probe suggest alterations in lipid regions of the cell wall. Implications of these results for understanding therapeutic effect of nitrogen laser on drug-resistant tuberculosis are discussed. PMID:15278725

  19. Effect on isoflavone of soybean seedlings by 532nm laser irradiation

    NASA Astrophysics Data System (ADS)

    Tian, J.; Jin, L. H.; Li, J. M.; Shen, B. J.; Wang, C. Y.; Lu, X.; Zhao, X. L.

    2010-02-01

    We took soybeans as experimental substance to study how the 532nm laser with different power density and irradiation time affected the pullulation ratio of the soybeans, average height of seedlings and the isoflavone content of seedlings' cotyledon and laminae. The mechanism that laser pretreatment of soybean seeds could increase the isoflavone content of the seedlings was discussed in such both aspects as the efficiency of the photosynthesis and the activity of a phenylalanine ammonia-lyase (PAL) as an initial enzyme for synthesizing the isoflavone. The results showed that after the soybean seeds were pretreated by laser, the activity of the PAL and the resultants of the photosynthesis such as the sugar of dissolubility, the sucrose, and the amylum all increased with the soybean seeds irradiated by laser in which the effect on the soybean seeds pretreated by 15mW/mm2 laser for 5 min was the most obvious. As a result, the photosynthesis efficiency of the soybean seedlings increased after being pretreated by laser, which might offer the foundation for accumulating a large amount of isoflavone.

  20. Effect on isoflavone of soybean seedlings by 532nm laser irradiation

    NASA Astrophysics Data System (ADS)

    Tian, J.; Jin, L. H.; Li, J. M.; Shen, B. J.; Wang, C. Y.; Lu, X.; Zhao, X. L.

    2009-10-01

    We took soybeans as experimental substance to study how the 532nm laser with different power density and irradiation time affected the pullulation ratio of the soybeans, average height of seedlings and the isoflavone content of seedlings' cotyledon and laminae. The mechanism that laser pretreatment of soybean seeds could increase the isoflavone content of the seedlings was discussed in such both aspects as the efficiency of the photosynthesis and the activity of a phenylalanine ammonia-lyase (PAL) as an initial enzyme for synthesizing the isoflavone. The results showed that after the soybean seeds were pretreated by laser, the activity of the PAL and the resultants of the photosynthesis such as the sugar of dissolubility, the sucrose, and the amylum all increased with the soybean seeds irradiated by laser in which the effect on the soybean seeds pretreated by 15mW/mm2 laser for 5 min was the most obvious. As a result, the photosynthesis efficiency of the soybean seedlings increased after being pretreated by laser, which might offer the foundation for accumulating a large amount of isoflavone.

  1. Simultaneous tri-wavelength laser operation at 916, 1086, and 1089 nm of diode-pumped Nd:LuVO4 crystal

    NASA Astrophysics Data System (ADS)

    Shen, Bingjun; Jin, Lihong; Zhang, Jiajia; Tian, Jian

    2016-09-01

    We report a diode-pumped continuous-wave tri-wavelength Nd:LuVO4 laser operating at 916, 1086, and 1089 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous tri-wavelength laser operation. Using a T-shaped cavity, we realized efficient tri-wavelength operation at 4F3/2  →  4I9/2 and 4F3/2  →  4I11/2 transitions for Nd:LuVO4 crystal, simultaneously. The maximum output power was 2.8 W, which included 916, 1086, and 1089 nm, and the optical conversion efficiency was 15.1%. To our knowledge, this is the first work that realizes simultaneous tri-wavelength Nd:LuVO4 laser operation.

  2. Doppler-free spectroscopy of mercury at 253.7 nm using a high-power, frequency-quadrupled, optically pumped external-cavity semiconductor laser.

    PubMed

    Paul, Justin; Kaneda, Yushi; Wang, Tsuei-Lian; Lytle, Christian; Moloney, Jerome V; Jones, R Jason

    2011-01-01

    We have developed a stable, high-power, single-frequency optically pumped external-cavity semiconductor laser system and generate up to 125 mW of power at 253.7 nm using successive frequency doubling stages. We demonstrate precision scanning and control of the laser frequency in the UV to be used for cooling and trapping of mercury atoms. With active frequency stabilization, a linewidth of <60 kHz is measured in the IR. Doppler-free spectroscopy and stabilization to the 6(1)S(0)-6(3)P(1) mercury transition at 253.7 nm is demonstrated. To our knowledge, this is the first demonstration of Doppler-free spectroscopy in the deep UV based on a frequency-quadrupled, high-power (>1 W) optically pumped semiconductor laser system. The results demonstrate the utility of these devices for precision spectroscopy at deep-UV wavelengths. PMID:21209687

  3. Highly efficient TEM00 mode LD-pumping 1063nm Nd:GdVO4 laser with short cavity

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojuan; Fu, Shenggui; Ge, Xiaolu; Yuan, Changkun

    2011-11-01

    A highly efficient TEM00 mode 1063 nm Nd:GdVO4 laser is accomplished with a simple plano-plano resonator. The laser threshold pump power is 856 mW. The maximum laser power of 2.05W is achieved when the pump power is 3.76 W, corresponding to a slope-efficiency of 70% to absorbed pump power. The quality of the output beam is analyzed with a laser beam quality analyzer. The perfect laser beam quality is partially attributed to the short cavity length of 11 mm and the precise temperature control to the Nd:GdVO4 crystal. The output laser central wavelength is 1063.1 nm with a laser linewidth of 0.06 nm.

  4. Simulation-based formulation of a nonchemically amplified resist for 257-nm laser mask fabrication

    NASA Astrophysics Data System (ADS)

    Rathsack, Benjamen M.; Tabery, Cyrus E.; Stachowiak, Timothy B.; Albelo, Jeff A.; Willson, C. Grant

    2000-06-01

    The demand for smaller and more uniform features on photomasks has inspired consideration of a DUV (257 nm) resist process for optical pattern generation. Chemically amplified resists require storage and exposure in carbon filtered environments, and they require post-exposure bakes. Few mask facilities are set up to handle chemically amplified resists commonly used in deep UV wafer fabrication process. Hence, it is appropriate to explore the lithographic performance of non-chemically amplified resist materials for 257 nm laser photomask lithography. Resist characterization and lithography simulation were used to formulate a 257 nm resist from DNQ/novolak materials provided by a commercial resist supplier. Diazonaphthoquinone (DNQ)/novolak resists have not been used for DUV Integrated Circuit (IC) applications mainly due to the low sensitivity and the strong absorbance of the DNQ photoactive compound (PAC) at 248 nm. However, a 2,1,4 DNQ based resist has been characterized that bleaches at 257 nm and inhibits novolak. The photoproduct of the 2,1,4 DNQ PAC is much more transparent at 257 nm than 248 nm. Novolak resin also has an absorbance minimum in the DUV at 257 nm that provides transparency similar to poly (hydroxystyrene). Traditional photoresist formulation requires tedious, iterative, and expensive manufacturing trials. Resist characterization and lithography simulation can be used to relate lithographic performance (resolution, sidewall and process latitude) to resist formulation parameters (PAC concentration, developer concentration, etc.), thereby supporting the formulation optimization. An exposure system using a 257 nm frequency doubled argon laser system has been constructed to study the resist photokinetics. Dill exposure parameters (A, B and C) have been extracted for a 2,1,4 DNQ/novolak based resist. Dissolution rate measurements have been made with a development rate monitor developed at the University of Texas at Austin. Simulation using the

  5. Sturge-Weber syndrome type II treated with PDL 595 nm laser.

    PubMed

    Kowalska-Brocka, Joanna; Brocki, Maciej; Uczniak, Sebastian; Uczniak, Kamila; Kaszuba, Andrzej; Jurowski, Piotr

    2015-02-01

    Sturge-Weber syndrome (SWS) is rare congenital disorder presenting facial port-wine stains (PWS) eye abnormalities and cerebrovascular malformations. The frequency of SWS is estimated at 1 in 50 000. Cerebrovascular abnormalities can be responsible for seizures, hemiparesis, mental retardation and ophthalmologic abnormalities cause intraocular pressure, glaucoma. Etiopathogenesis of SWS remains elusive. We present a case of a 7-year-old girl with SWS type II. A port-wine stain involves the upper right part of half face and has been associated with glaucoma of both eyes. In the Department of Dermatology in 2009-2012 we performed 23 procedures within 2 months. We have been using PDL laser at wavelength 595 nm and very good cosmetic results were achieved. Given positive treatment effects, the laser therapy of port-wine stains is a method of selection. Port-wine stains in the course of SWS requires a large number of laser treatment. PMID:25821431

  6. Emission parameters and thermal management of single high-power 980-nm laser diodes

    SciTech Connect

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

    2014-02-28

    We report emission parameters of high-power cw 980-nm laser diodes (LDs) with a stripe contact width of 100 μm. On copper heat sinks of the C-mount type, a reliable output power of 10 W is obtained at a pump current of 10 A. Using a heat flow model derived from analysis of calculated and measured overall efficiencies at pump currents up to 20 A, we examine the possibility of raising the reliable power limit of a modified high-power LD mounted on heat sinks of the F-mount type using submounts with optimised geometric parameters and high thermal conductivity. The possibility of increasing the maximum reliable cw output power to 20 W with the use of similar laser crystals is discussed. (lasers)

  7. Saturated 13.2 nm high-repetition-rate laser in nickellike cadmium

    NASA Astrophysics Data System (ADS)

    Rocca, J. J.; Wang, Y.; Larotonda, M. A.; Luther, B. M.; Berrill, M.; Alessi, D.

    2005-10-01

    We report gain-saturated operation of a 13.2 nm tabletop laser in Ni-like Cd at a 5 Hz repetition rate. A gain-length product G×L=17.6 was obtained by heating a precreated plasma with 8 ps duration Ti:sapphire laser pulses with an energy of only 1 J impinging at a grazing angle of 23°. With an average power of ˜1 µW, this laser is an attractive coherent source for at-wavelength metrology of extreme UV lithography optics and other applications. [Note: Due to a production error in the print version abstract, the value "1 µW" is incorrectly stated as "1 mW." This value is stated correctly in the online PDF.

  8. Thermal lensing characterization of a high-radiance 946nm planar waveguide laser

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    We present the characterization of the in-plane thermal lens in a quasi-four-level Nd:YAG planar waveguide (PW) laser configured for high-radiance operation with an external stable-cavity. Our approach utilises the measurement of the laser's output irradiance distribution at the near- and far-field positions concurrently in order to obtain the "real time" beam propagation parameter and thus beam quality factor, M2. Coupled with the knowledge of the intra-cavity-thermal-lens- dependent beam sizes at an intra-cavity beam waist, the power dependent effective thermal lens focal length was characterized. A thermal lens focal length of >450 mm was obtained at all incident pump powers up to the maximum level of 87 W. This characterization enabled the build of a 29 W 946 nm PW laser with a record output radiance of 4.3 TWm-2sr-1.

  9. Clinical Application of 810nm Diode Laser to Remove Gingival Hyperplasic Lesion

    PubMed Central

    Asnaashari, Mohammad; Azari-Marhabi, Saranaz; Alirezaei, Somayeh; Asnaashari, Nikoo

    2013-01-01

    Introduction: Several treatment options have been introduced for removal of gingival hyperplasic lesions, but using diode lasers have many advantages such as less bleeding, time saving, better shaping, improved healing and less complication for the patients. Case: A 15-year-old girl with multiple fibroma-like lesions in the oral cavity, who had a medical history of tuberous sclerosis, was selected for gingivoplasty treatment with 810nm diode laser. Result: A perfect shaping was obtained after removal of the whole lesion in one session and no recurrence was observed in 6 months. Conclusion: Using laser in the treatment of oral lesions leads to excellent wound healing along with excellent functional results. PMID:25606315

  10. Compact second-harmonic generation laser module with 1 W optical output power at 490 nm.

    PubMed

    Fiebig, Christian; Sahm, Alexander; Uebernickel, Mirko; Blume, Gunnar; Eppich, Bernd; Paschke, Katrin; Erbert, Götz

    2009-12-01

    We demonstrate continues-wave 1 W at 490 nm on a 2.5 cm(3) micro-optical bench using single-path second-harmonic generation with a periodically poled MgO:LiNbO(3) bulk crystal. The pump laser is a distributed Bragg reflector tapered diode laser having a single-frequency spectrum and a pump power of 9.5 W. Based on that 1 W blue light could be achieved resulting in an optical conversion efficiency of 11%. Furthermore, the module has an output power stability of better than 2% and the blue laser beam shows an nearly diffraction limited beam quality of M(2)(sigma) = 1.2 in vertical and M(2)(sigma) = 2 in lateral direction. PMID:20052204

  11. Resonant photo-acoustic detection of carbon monoxide with UV Laser at 213 nm

    NASA Astrophysics Data System (ADS)

    Khalil, A. A. I.; Gondal, M. A.; Al-Suliman, N.

    2011-05-01

    A trace-gas sensor for carbon monoxide based on Pulsed Laser-Induced Photo-Acoustic Spectroscopy (PLIPAS) in conjunction with laser excitation wavelength of 213 nm was designed, fabricated and tested for the first time. PLIPAS-based sensor with different cell geometry was employed to enhance the sensitivity down to 58 ppbV level. The parametric dependence of the PLIPAS signals on CO gas concentration, buffer gas (Ar, O2 and He) concentration, laser pulse energy was studied and Ar proved to be better than O2 and He in terms of enhancing the sensitivity of the system. The signal-to-noise ratio and limit of detection have been quantified for different experimental conditions. This study proves that PLIPAS-based CO gas sensor is a reliable gas-leak detection system with high sensitivity and selectivity. Hence this sensor can be employed for pollution monitoring and detection of CO in a noisy environment.

  12. Effect of low-level pulsed laser 890-nm on lumbar spondylolisthesis: a case report

    NASA Astrophysics Data System (ADS)

    Mortazavi, Seyed M. J.; Afsharpad, Mitra; Djavid, Gholam-reza E.

    2002-10-01

    Objective: Evaluating the effectiveness of low-level laser therapy (LLLT) in alleviating the symptoms of lumbar spondylolisthesis. Materials and Methods: Laser was irradiated for 2 mm at six symmetric points along the lumbosacral spine and 5 points along the referred point ofpain, six times a week for 2 weeks (890 nm; 8 J/cm2; pulsed at 1500 Hz). Perception of benefit, level of function was assessed by the Oswestry disability index, lumbar mobility range of motion and low back pain intensity. Results and Discussion: Results showed a complete reduction in pain and improvement in function in the patient. This case report suggests that low-level laser therapy (LLLT) could play a role in conservative management of low-grade lumbar spondylolisthesis.

  13. Surface modification during Nd:YAG (1064 nm) pulsed laser cleaning of organic fibrous materials

    NASA Astrophysics Data System (ADS)

    Strlič, Matija; Kolar, Jana; Šelih, Vid-Simon; Marinček, Marko

    2003-02-01

    Formation of yellow chromophores on artificially soiled surfaces of cellulose sheets, rag paper, linen, cotton, wool and silk during Nd:YAG (1064 nm) pulsed laser cleaning was followed using Vis and FTIR diffuse reflectance spectrometry. Content of reducing carbonyl groups and changes in FTIR reflectance spectra of cellulose are indicative of surface chemical modifications typical of thermal degradation at elevated temperatures. Two types of soiling were used: well-characterised natural dust and carbon powder and no difference in laser-induced formation of chromophores on material surface was observed at low deposit densities. The influence of laser fluence and number of repetitions was studied and a single pulse of a higher fluence (1 J cm -1) is in general more advisable. No bleaching of the chromophores formed was noticed after repeated treatments.

  14. Optical measurement of temperature in biological cells under infrared laser light exposure (λ=800 nm)

    NASA Astrophysics Data System (ADS)

    Moreau, David; Lefort, Claire; Leveque, Philippe; O'Connor, Rod P.

    2015-07-01

    Interest in the interaction between laser light and biological samples has gained momentum in recent years, particularly in neurobiology, where there is significant potential to stimulate neurons with infrared laser light. Despite recent reports showing the application of infrared light for neurostimulation, the underlying mechanism is still unknown. The two main hypotheses are based on thermal or electrostatic mechanisms. Here, a novel optical method is presented to make temperature measurements in human neural cells under infrared laser excitation (λ=800nm) using the dye Rhodamine B (RhB). The measurement of temperature is based on the property of RhB, a fluorescent dye whose fluorescence intensity decreases linearly with increases in temperature. We present and detail the setup and measurement procedure that has temporal resolution of few milliseconds, based around a fluorescent live-cell imaging microscope used for cellular microfluorimetry experiments.

  15. Methods for Mitigating Growth of Laser-Initiated Surface Damage on DKDP Optics at 351nm

    SciTech Connect

    Hrubesh, L W; Brusasco, R B; Grundler, W; Norton, M A; Donohue, E E; Molander, W A; Thompson, S L; Strodtbeck, S R; Whitman, P K; Shirk, M D; Wegner, P J; Nostrand, M C; Burnham, A K

    2002-10-11

    We report an experimental investigation of mitigating surface damage growth at 351nm for machine-finished DKDP optics. The objective was to determine which methods could be applied to pre-initiated or retrieved-from-service optics, in order to stop further damage growth for large aperture DKDP optics used in high-peak-power laser applications. The test results, and the evaluation thereof, are presented for several mitigation methods applied to DKDP surface damage. The mitigation methods tested were CW-CO{sub 2} laser processing, aqueous wet-etching, short-pulse laser ablation, and micro-machining. We found that micro-machining, using a single crystal diamond tool to completely remove the damage pit, produces the most consistent results to halt the growth of surface damage on DKDP. We obtained the successful mitigation of laser-initiated surface damage sites as large as 0.14mm diameter, for up to 1000 shots at 351nm and fluences in the range of 2 to 13J/cm{sup 2}, {approx} 11ns pulse length. Data obtained to-date indicates that micro-machining is the preferred method to process large-aperture optics.

  16. Application of Laser Shock Processing System by Underwater Irradiation (1064 nm) in Metal Surface

    NASA Astrophysics Data System (ADS)

    Gomez-Rosas, G.; Rubio-González, C.; Ocaña, J. L.; Molpeceres, C.; Porro, J. A.; Morales, M.; Casillas, F. J.; Mora-Gonzalez, M.; Peña-Lecona, F. G.

    2008-04-01

    Laser shock processing (LSP) is a technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life, reduces fatigue crack growth rate and increases wear resistance of metals. We present a configuration and results in the LSP concept for metal surfaces treatments in underwater layer with constant thickness using laser irradiation at 1064 nm. A convergent lens is used to deliver 2, 5 J/cm2 in a 8 ns laser FWHM pulse produced by a Q-switch Nd:YAG Laser. Experimental results using a pulse density of 5 000 pulses/cm2 and spots of 0, 8 mm to 1, 5 mm in diameter on AISI 1040 steel surfaces, Ti6A14V surfaces, 304 Stainless Steel surface and 6061-T6 Aluminum surfaces are presented. A compressive residual stress distribution as a function of depth is assessed by the hole drilling method. High level compressive residual stresses are produced using a 1064 nm wavelength. This method can be applied for surface treatment of final metal products.

  17. Optimization of Laser-Damage Resistance of Evaporated Hafnia Films at 351 nm

    SciTech Connect

    Oliver, J.B.; Papernov, S.; Schmid, A.W.; Lambropoulos, J.C.

    2009-04-07

    A systematic study was undertaken to improve the laser-damage resistance of multilayer high-reflector coatings for use at 351 nm on the OMEGA EP Laser System. A series of hafnium dioxide monolayer films deposited by electron-beam evaporation with varying deposition rates and oxygen backfill pressures were studied using transmission electron microscopy (TEM), x-ray diffraction (XRD), and refractive index modeling. These exhibit microstructural changes for sufficiently slow deposition rates and high oxygen backfill pressures, resulting in an absence of crystalline inclusions and a lower refractive index. Hafnia monolayers exhibited laser-damage resistance as high as 12 J/cm^2 at 351 nm with a 0.5-ns pulse. This process was utilized in the fabrication of reduced electric-field-type multilayer high-reflector coatings. Measured laser-damage thresholds as high as 16.63 J/cm^2 were achieved under identical test conditions, an exceptional improvement relative to historical damage thresholds of the order of 3 to 5 J/cm^2.

  18. Safety of cornea and iris in ocular surgery with 355-nm lasers

    NASA Astrophysics Data System (ADS)

    Wang, Jenny; Chung, Jae Lim; Schuele, Georg; Vankov, Alexander; Dalal, Roopa; Wiltberger, Michael; Palanker, Daniel

    2015-09-01

    A recent study showed that 355-nm nanosecond lasers cut cornea with similar precision to infrared femtosecond lasers. However, use of ultraviolet wavelength requires precise assessment of ocular safety to determine the range of possible ophthalmic applications. In this study, the 355-nm nanosecond laser was evaluated for corneal and iris damage in rabbit, porcine, and human donor eyes as determined by minimum visible lesion (MVL) observation, live/dead staining of the endothelium, and apoptosis assay. Single-pulse damage to the iris was evaluated on porcine eyes using live/dead staining. In live rabbits, the cumulative median effective dose (ED50) for corneal damage was 231 J/cm2, as seen by lesion observation. Appearance of endothelial damage in live/dead staining or apoptosis occurred at higher radiant exposure of 287 J/cm2. On enucleated rabbit and porcine corneas, ED50 was 87 and 52 J/cm2, respectively, by MVL, and 241 and 160 J/cm2 for endothelial damage. In human eyes, ED50 for MVL was 110 J/cm2 and endothelial damage at 453 J/cm2. Single-pulse iris damage occurred at ED50 of 208 mJ/cm2. These values determine the energy permitted for surgical patterns and can guide development of ophthalmic laser systems. Lower damage threshold in corneas of enucleated eyes versus live rabbits is noted for future safety evaluation.

  19. High power 355 nm diode-pumped solid-state laser

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Cheng, Chee Yuen; Peng, Xiaoyuan; Yong, Saw Soon

    2015-07-01

    This paper reported a high-power diode-pumped solid-state laser for material processing applications with a target of more than 60 ns pulse width at 355 nm. As known, long pulse width IR laser (around 70-100 ns) is difficult to get high conversion efficiency to UV since the peak power is more than 2 times lower than 20-30 ns laser. However, the unique long pulse width characteristic makes the laser an ideal tool for flexible PCB drilling with 30-50 μm holes and for cutting portable devices. Up to 52.2% IR to UV conversion efficiency was obtained by our novel intra-cavity harmonic generation cavity design. A 9.3W UV output at 30 kHz was demonstrated with compact intra-cavity sum frequency design. Special conduction cooling-designed LD side-pumped module provided 17.8 W fundamental IR output power with AOM q-switching. The UV output pulse width is 76 ns at 30 kHz and 140 ns at 70 kHz. The type I and type II phase matching LBOs were used for intra-cavity harmonic generations of 355 nm. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated. The experimental results are in agreement with the theoretical modelling. This system will also be useful for many material processing applications such as PCB cutting and wafer scribing.

  20. Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

    NASA Astrophysics Data System (ADS)

    Bonse, J.; Höhm, S.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Rosenfeld, A.; Krüger, J.

    2016-06-01

    Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

  1. Preparation and disinfection of root canals by 308-nm excimer laser light

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim; Folwaczny, Matthias; Lehn, Norbert

    1994-09-01

    Conventional root canal treatments often fail due to insufficient removal of root canal contents and due to ineffective reduction of bacterial growth. In vitro investigations on the 308 nm excimer laser root canal preparation showed excellent results concerning the preparation quality. The aim of the present study was to investigate the influence of 308 nm excimer laserlight on the growth of bacteria. Bacterial suspensions of Staph. aureus, E. coli, and Enterococcus faec. were irradiated with various energy densities and different time duration. In order to exclude thermal side effects the temperature rise inside the suspensions was registered during irradiation. It was able to demonstrate that 308 nm excimer laserlight effects a log reduction of germ concentration at energy densities of 0.5 - 2.4 J/cm2. Laserlight effects germ reduction even without tissue removal. The effectiveness is dependent on the type of bacteria, the energy density, and the time of irradiation. The antimicrobial effect is independent from temperature.

  2. Continuous-wave dual-wavelength Nd:YAG laser operation at 1319 and 1338 nm

    NASA Astrophysics Data System (ADS)

    Sun, G. C.; Lee, Y. D.; Zao, Y. D.; Xu, L. J.; Wang, J. B.; Chen, G. B.; Lu, J.

    2013-04-01

    We report an efficient continuous-wave (CW) dual-wavelength operation of an Nd:YAG (YAG: yttrium aluminum garnet) laser at 1319 and 1338 nm. An output power of 2.47 W for the dual-wavelength operation was achieved at the incident pump power of 16.7 W. Intracavity sum-frequency mixing at 1319 and 1338 nm was then realized in an LBO (lithium triborate) crystal to reach the red range. A maximum output power of 879 mW in the red spectral range at 664 nm has been achieved. The red output stability is better than 3.4%. The red beam quality M2 values are about 1.21 and 1.35 in the horizontal and vertical directions respectively.

  3. 2.14 mW deep-ultraviolet laser at 165 nm by eighth-harmonic generation of a 1319 nm Nd:YAG laser in KBBF

    NASA Astrophysics Data System (ADS)

    Dai, Shi-Bo; Chen, Ming; Zhang, Shen-Jin; Wang, Zhi-Min; Zhang, Feng-Feng; Yang, Feng; Wang, Zhi-Chao; Zong, Nan; Liu, Li-Juan; Wang, Xiao-Yang; Zhang, Jing-Yuan; Bo, Yong; Cui, Da-Fu; Peng, Qin-Jun; Li, Ru-Kang; Chen, Chuang-Tian; Xu, Zu-Yan

    2016-03-01

    We report a nanosecond (ns) 165 nm deep-ultraviolet (DUV) laser with a maximum average power of 2.14 mW by eighth-harmonic generation (EHG) of a homemade ns 1319 nm Nd:YAG laser. The EHG was performed by cascaded second-harmonic generation (SHG) through successive stages of two LiB3O5 crystals and one KBe2BO3F2 crystal. The generated radiation at 165 nm is the shortest DUV wavelength ever generated through SHG method and the highest average power of all solid state lasers below 170 nm to our knowledge. Such a ns DUV laser at 165 nm is of great interest for photoemission spectroscopy and Raman spectroscopy.

  4. Initial clinical results of laser prostatectomy procedure for symptomatic BPH using a new 50-watt diode laser (wavelength 1000 nm)

    NASA Astrophysics Data System (ADS)

    Bhatta, Krishna M.

    1995-05-01

    Lasers have been used for symptomatic Benign Prostatic Hyperplasia (BPH) in both contact and non-contact modes with reported success rates equivalent to that of Transurethral Resection of Prostate (TURP). A new high power diode laser (Phototome), capable of delivering up to 50 watts of 1000 nm wavelength laser power via a 1 mm quartz fiber, was used to treat 15 patients with symptomatic BPH. Five patients had acute retention, 3 had long term catheter (7 - 48 months), and 8 had severe prostatism. Spinal anesthesia was used in 11 patients, and 4 patients had local anesthesia and intravenous sedation. Four quadrant coagulation with an angle firing probe delivering 50 watts of laser power for 60 seconds in one quadrant was used as the core of the treatment in 11 patients, contact vaporization of BPH tissue was performed in one patient using a 4.5 mm ball tip was used in one patient and three patients with bladder neck stenosis had bladder neck incision performed using a 1 mm quartz fiber delivering 30 watts of laser power. A foley catheter was left indwelling and removed after 5 - 7 days. All patients except one were catheter free after a mean of 8 days. One patient continued to have severe prostatism and had a TURP performed with good results after 3 months of his laser prostatectomy procedure. AUA symptom scores available in 11 patients was found to be 4 after 1 - 3 months of the initial procedure.

  5. The ASE noise of a Yb3+-doped phosphate fiber single-frequency laser at 1083 nm

    NASA Astrophysics Data System (ADS)

    Li, Can; Xu, Shanhui; Feng, Zhouming; Xiao, Yu; Mo, Shupei; Yang, Changsheng; Zhang, Weinan; Chen, Dongdan; Yang, Zhongmin

    2014-02-01

    A thorough investigation of the effect of amplified spontaneous emission (ASE) on the noise characteristics of a heavily Yb-doped phosphate fiber single-frequency laser at 1083 nm was made. Both the intensity noise and the frequency noise were measured and analyzed by introducing a band pass filter (BPF) into the fiber laser. For the intensity noise, it was found that the ASE noise is present at frequencies beyond the resonant relaxation oscillation (RRO) and until 6 MHz at low pump intensity, while it is diminished in the high power regime. Under a pump power of 42 mW, a maximum reduction of over 3 dB of the relative intensity noise (RIN) was observed with the help of the BPF. As for the frequency noise, a transition of the dominating noise sources from ASE noise in the low pump intensity condition to pump noise in the high pump intensity condition was observed. In the low power condition, more than 7 dB of the ASE noise was found to add to the frequency noise spectrum. It is believed that the obtained results will be helpful in understanding and optimizing the noise characteristics of this type of fiber laser.

  6. Cost-effective laser interference lithography using a 405 nm AlInGaN semiconductor laser

    NASA Astrophysics Data System (ADS)

    Byun, Ikjoo; Kim, Joonwon

    2010-05-01

    This paper presents a cost-effective interference lithography system that uses a 405 nm AlInGaN semiconductor laser. This method is cost-effective because the AlInGaN semiconductor laser has a long coherence length (~20 m) and low price (e.g. only 1/3 that of the HeCd laser). This system successfully fabricated uniform nano-periodic patterns (line, dot and hole) in a photoresist (PR) over a 2 × 2 cm sample area. The PR patterns agreed well with simulations. Tall silicon nano-structures were fabricated by deep reactive ion etching (DRIE) using a PR pattern as a direct etch mask layer. Aspect ratios of 25 with smooth and vertical sidewalls were achieved after 32 DRIE cycles.

  7. A green laser at 517 nm based on intracavity frequency doubling of the diode-pumped Yb:LO laser

    NASA Astrophysics Data System (ADS)

    Li, Yong-liang; Li, Xiu-fei; Hu, Hong-wei; Hai, Xiao-quan; Liu, Yang; Wang, Jin-nan

    2014-09-01

    We report for the first time, to our knowledge, the diode-pumped continuous-wave (CW) thin-disk Yb3+-doped Lu2O3 (Yb:LO) laser at 1 034 nm and the second-harmonic generation at 517 nm. With a 6.3% output coupler, the maximum output power is 1.17 W under a pump power of 18.5 W. Moreover, the intracavity second-harmonic generation (SHG) is also achieved with power of 193 mW at 517 nm by using an LiB3O5 (LBO) nonlinear crystal. The beam quality factor M 2 is about 1.28. The fluctuation of the output power is about 3% in 1 h.

  8. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    SciTech Connect

    Egorov, A. Yu. Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Nevedomskiy, V. N.; Bugrov, V. E.

    2015-11-15

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of In{sub x}Ga{sub 1–x}As with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer.

  9. The Effect of Q-Switched Nd:YAG 1064 nm/532 nm Laser in the Treatment of Onychomycosis In Vivo

    PubMed Central

    Kalokasidis, Kostas; Onder, Meltem; Trakatelli, Myrto-Georgia; Richert, Bertrand; Fritz, Klaus

    2013-01-01

    In this prospective clinical study, the Q-Switched Nd:YAG 1064 nm/532 nm laser (Light Age, Inc., Somerset, NJ, USA) was used on 131 onychomycosis subjects (94 females, 37 males; ages 18 to 68 years). Mycotic cultures were taken and fungus types were detected. The laser protocol included two sessions with a one-month interval. Treatment duration was approximately 15 minutes per session and patients were observed over a 3-month time period. Laser fluencies of 14 J/cm2 were applied at 9 billionths of a second pulse duration and at 5 Hz frequency. Follow-up was performed at 3 months with mycological cultures. Before and after digital photographs were taken. Adverse effects were recorded and all participants completed “self-evaluation questionnaires” rating their level of satisfaction. All subjects were well satisfied with the treatments, there were no noticeable side effects, and no significant differences were found treating men versus women. At the 3-month follow-up 95.42% of the patients were laboratory mycologically cured of fungal infection. This clinical study demonstrates that fungal nail infections can be effectively and safely treated with Q-Switched Nd:YAG 1064 nm/532 nm laser. It can also be combined with systemic oral antifungals providing more limited treatment time. PMID:24396343

  10. Progress in LA-ICP-MS Microanalysis Using a 200 nm-femtosecond Laser

    NASA Astrophysics Data System (ADS)

    Jochum, K. P.; Stoll, B.; Weis, U.; Jacob, D. E.; Mertz-Kraus, R.; Andreae, M. O.

    2013-12-01

    We have investigated the performance of LA-ICP-MS for the microanalysis of a variety of samples of different matrices using the 200 nm Ti-sapphire based fs-laser ablation system NWR Femto200 combined with the sector-field ICP-MS Thermo Element2. For comparison, we conducted similar experiments with three ns lasers: 193 nm Nd:YAG, 213 nm Nd:YAG, 193 nm ArF excimer. Measurements were performed with different spot sizes (10 - 65 μm), pulse repetition rates (5 - 250 Hz) and energy densities (0.5 - 0.7 Jcm-2) in spot and line scan analysis modes. We applied those settings to well-characterized and homogeneous synthetic silicate, geological, carbonate and phosphate microanalytical reference materials from NIST, USGS, MPI-DING and others. Our investigations show that in the case of UV-fs laser ablation line scan analysis is much more appropriate than spot analysis. In contrast to the ns lasers, fs laser spot analysis is characterized by a strong decrease of ion intensities, presumably caused by the generation of color centers by fs laser pulses [1]. On the other hand, line scan analyses yield uniform and relative high ion intensities so that detection limits for the various elements are similar to ns laser ablation. In LA-ICP-MS, the major limitations regarding measurement accuracy are matrix effects. The experiments demonstrate that in each case the fs data are more reproducible and less matrix-dependent with respect to fractionation factors [2] and mass-load induced matrix effects [3] than the results obtained using the ns lasers. The fractionation factors of refractory, volatile, lithophile and chalcophile elements are unity for the line scan mode and agree within an uncertainty of 1 %, whereas significantly lower, but matrix-independent, values for the volatile elements Pb (0.93 × 0.03) and Zn (0.88 × 0.04) were observed using the spot analysis mode. This implies that calibration can be performed reliably for quite different matrices using certified silicate

  11. Our perspective of the treatment of naevus of Ota with 1,064-, 755- and 532-nm wavelength lasers.

    PubMed

    Felton, S J; Al-Niaimi, F; Ferguson, J E; Madan, V

    2014-09-01

    Naevus of Ota (NO) is a disfiguring pigmentary disorder affecting the face. Q-switched neodymium-doped yttrium aluminium garnet (QS Nd:YAG)-1,064 nm is a standard laser treatment because it causes highly selective destruction of melanin within the aberrant dermal melanocytes. However, not all lesions respond. This study aims to evaluate the efficacy/safety of QS Nd:YAG-1,064 nm and the shorter wavelength QS Alexandrite-755 nm and QS Nd:YAG-532 nm lasers in treating NO. Data were evaluated from 21 patients treated in our laser centre from 2004 to 2012. Lesional skin was irradiated with QS-532 nm/QS-755 nm/QS-1,064 nm, with settings titrated according to responses. All received initial test patches to direct initial wavelength choice, with subsequent treatments at 3-monthly intervals until clearance/lack of further response. Laser modality was switched following repeated test patches if there was no or no sustained improvement. Two thirds of patients had ≥ 90% improvement compared to baseline photographs. In 20% of patients, QS-1,064 nm was most efficacious with 97% mean improvement. The mean improvement was 80% for those in whom QS-755 nm was superior, and 90% for QS-532 nm. Median number of overall laser treatments was 8 (range 4-13). Number of treatments required varied significantly according to lesional colour and site: grey lesions and those on the forehead/temple were most resistant. We confirm successful treatment of NO with QS Nd:YAG-1,064 nm and the shorter wavelength QS-755 nm/QS-532 nm lasers without serious or irreversible side effects. We recommend judicious test patch analysis before treatment and a modality switch if complete clearance is not obtained. PMID:23640036

  12. High performances of very long (13.5mm) tapered laser emitting at 975 nm

    NASA Astrophysics Data System (ADS)

    Resneau, P.; Garcia, M.; Lecomte, M.; Robert, Y.; Vinet, E.; Parillaud, O.; Krakowski, M.; Boiko, D. L.

    2016-03-01

    Mode-locked semiconductor laser technology is a promising technology candidate considered by European Space Agency (ESA) for optical metrology systems and other space applications in the context of high-precision optical metrology, in particular for High Accuracy Absolute Long Distance Measurement. For these applications, we have realised a multi-section monolithic-cavity tapered laser diode with a record cavity length of 13.5 mm. The laser operates at 975 nm wavelength. It is designed for the emission of ultra-short optical pulses (<1 ps) at a repetition rate of 3 GHz with an average optical power of 600 mW. It is based on a MOVPE grown laser structure with Aluminium free active region enabling high optical gain, low internal losses and low series resistance. The first results obtained under CW pumping of such centimetre-long laser at 20 °C heatsink temperature show the lasing threshold current as low as 1.27 A and the differential external efficiency as high as 0.55 W/A.

  13. Microsurgery of the retina with a needle-guided 193-nm excimer laser.

    PubMed

    Lewis, A; Palanker, D; Hemo, I; Pe'er, J; Zauberman, H

    1992-07-01

    This article presents a method used to guide the beam from an argon fluoride excimer laser to make it suitable for microsurgical purposes and confine it to areas that can be varied in dimension from 1 micron to tens or hundreds of microns. This approach guides the excimer laser beam with an articulated mechanical arm and confines it with variable-diameter tapered tubes, possibly allowing the use of this laser in in vitro retinal surgery with endolaser techniques. Currently, because of the lack of a delivery and focusing system for the 193-nm argon fluoride beam and its absorption by biologic liquids, this laser is used exclusively in ophthalmology for topical applications, such as corneal sculpting. This new method resolves these problems in a unique way with impressive results. Specifically, it was shown that, with this needle-guided excimer laser, it is possible to remove retinal tissue accurately without detectable damage to surrounding cells. Applications of this new technique in retinal surgery are discussed. PMID:1634334

  14. A trace gas sensor using near infrared distributed feedback laser at 1654 nm

    NASA Astrophysics Data System (ADS)

    Li, Bin; He, Qi-Xin; Liu, Hui-Fang; Wang, Yi-Ding

    2015-08-01

    A cost-effective compact instrument for high-stable and sensitive detection of methane (CH4) based on the tunable diode laser absorption spectroscopy technique was experimentally demonstrated. A distributed feedback laser modulated at 1654 nm and two InGaAs photodiodes were deployed in this instrument. The laser was driven by the self-developed temperature and current controller. Spectrum measurements show that the center wavelength of the laser is stable and linearly controlled. Meanwhile, a self-developed digital lock-in amplifier was developed for the extraction of harmonics (1f, 2f) of the gas absorption signal. Experiments of gas detection were carried out to investigate the sensor performance. Firstly, the relation between gas concentration and 1f and 2f harmonics was measured and the relation curve was plotted for calibration. Then, results of accuracy test in different concentrations show that the maximum relative detection error is less than 5.6% in the range 0%-100%. Keeping the other experimental parameters constant, gas samples of 5% concentration was detected during a period of 8 h. The maximum detection error is less than 2.8%, suggesting good detection stability. The sensor can also be applied to field measurement of other gases by adopting lasers at relative wavelength.

  15. Laser diode-pumped dual-cavity high-power fiber laser emitting at 1150  nm employing hybrid gain.

    PubMed

    Chen, Yizhu; Xiao, Hu; Xu, Jiangming; Leng, Jinyong; Zhou, Pu

    2016-05-10

    We demonstrate a laser diode-pumped dual-cavity high-power fiber laser emitting at 1150 nm. The laser employs Yb and Raman gains simultaneously. The fiber laser with a simple structure achieves high-efficiency operation while efficiently suppressing the amplified spontaneous emission and parasitic oscillation. The maximum output power at 1150 nm is 110.8 W, with an optical-to-optical efficiency of 57%. Further power scaling at 1150 nm is expected with the optimization of the system design. PMID:27168299

  16. Diode λ830nm laser associated with hydroxyapatite and biological membranes: bone repair in rats

    NASA Astrophysics Data System (ADS)

    Carneiro, Vanda S. M.; Limeira, Francisco d. A.; Gerbi, Marleny E. M.; Menezes, Rebeca F. d.; Santos-Neto, Alexandrino P. d.; Araújo, Natália C.

    2016-02-01

    The aim of the present study was to histologically assess the effect of laser therapy (AsGaAl, 830nm, 40mW, CW, φ ~0,6mm, 16J/cm2 per session, four points of 4J/cm2) on the repair of surgical defects created in the femur of Wistar rats. Background data: Several techniques have been proposed for the correction of bone defects, including the use of grafts and membranes. Despite the increase in the use of laser therapy for the biomodulation of bone repair, very few studies have assessed the associations between laser light and biomaterials. Method: The defects were filled with synthetic micro granular hydroxyapatite (HA) Gen-phos® implants and associated with bovine bone membranes (Gen-derm®). Surgical bone defects were created in 48 rats and divided into four groups: Group IA (control, n=12); Group IB (laser, n=12); Group IIA (HA + membrane, n=12); Group IIB (HA + membrane + laser, n=12). The irradiated groups received the first irradiation immediately after surgery. This radiation was then repeated seven times every 48h. The animals were sacrificed after 15, 21, and 30 days. Results: When comparing the groups irradiated with implants and membranes, it was found that the repair of the defects submitted to laser therapy occurred more quickly, starting 15 and 21 days after surgery. By the 30th day, the level of repair of the defects was similar in the irradiated and the non-irradiated groups. New bone formation was confirmed inside the cavity by the implant's osteoconduction. In the irradiated groups, there was an increment of this new bone formation. Conclusions: In conclusion, the use of laser therapy, particularly when associated with hydroxyapatite and biological membranes, produced a positive biomodulation effect on the healing process of bone defects on the femurs of rats.

  17. Laser ablation of ceramic Al2O3 at 193 nm and 248 nm: The importance of single-photon ionization processes

    NASA Astrophysics Data System (ADS)

    Peláez, R. J.; Afonso, C. N.; Bator, M.; Lippert, T.

    2013-06-01

    The aim of this work is to demonstrate that single-photon photoionization processes make a significant difference in the expansion and temperature of the plasma produced by laser ablation of ceramic Al2O3 in vacuum as well as to show their consequences in the kinetic energy distribution of the species that eventually will impact on the film properties produced by pulsed laser deposition. This work compares results obtained by mass spectrometry and optical spectroscopy on the composition and features of the plasma produced by laser ablation at 193 nm and 248 nm, i.e., photon energies that are, respectively, above and below the ionization potential of Al, and for fluences between threshold for visible plasma and up to ≈2 times higher. The results show that the ionic composition and excitation of the plasma as well as the ion kinetic energies are much higher at 193 nm than at 248 nm and, in the latter case, the population of excited ions is even negligible. The comparison of Maxwell-Boltzmann temperature, electron temperatures, and densities of the plasmas produced with the two laser wavelengths suggests that the expansion of the plasma produced at 248 nm is dominated by a single population. Instead, the one produced at 193 nm is consistent with the existence of two populations of cold and hot species, the latter associated to Al+ ions that travel at the forefront and produced by single photon ionization as well as Al neutrals and double ionized ions produced by electron-ion impact. The results also show that the most energetic Al neutrals in the plasma produced at the two studied wavelengths are in the ground state.

  18. Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm

    NASA Astrophysics Data System (ADS)

    Tulea, Cristian-Alexander; Caron, Jan; Gehlich, Nils; Lenenbach, Achim; Noll, Reinhard; Loosen, Peter

    2015-10-01

    Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water-air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2 mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue.

  19. Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm.

    PubMed

    Tulea, Cristian-Alexander; Caron, Jan; Gehlich, Nils; Lenenbach, Achim; Noll, Reinhard; Loosen, Peter

    2015-10-01

    Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water–air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2  mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue. PMID:26469563

  20. Estimating laser transit anemometry noise performance capabilities

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    A Monte Carlo based LTA (laser transit anemometry) simulation system has been used to perform a detailed evaluation of a set of processing algorithms proposed by Mayo and Smart (1984) for the extraction of two-dimensional flow parameters from LTA data sets collected in a plane normal to the optical axis of the system. The present evaluation includes data ensembles containing 0.0, 5.0, 10.0, and 20.0 percent background noise levels in the constituent correlograms. The results of these evaluations indicate that for turbulence levels of up to 10.0 percent the processing system is able to extract the necessary flow parameters accurately from the LTA data sets. Mean velocity magnitude and flow angle are measurable to within 2.0 percent for turbulence intensity levels of up to 14.0 percent. Standard deviations are measureable to within 10.0 percent over a turbulence range of 3.0-10.0 percent at the same noise levels. These results indicate that the algorithms described have applications in fluid flow surveys.