Sample records for q-switching

  1. Q-Switching in a Neodymium Laser (United States)

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis


    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  2. Graphene Q-switched Yb:KYW planar waveguide laser

    NARCIS (Netherlands)

    Kim, Jun Wan; Choi, Sun Young; Aravazhi, S.; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Bae, Sukang; Ahn, Kwang Jun; Yeom, Dong-Il; Rotermund, Fabian

    A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in

  3. Q-switched laser tattoo removal

    Directory of Open Access Journals (Sweden)

    Viljem H. topčič


    Full Text Available Background: Decorative tattooing gained popularity in many western countries throughout the 1990s. Some estimates show that approximately 10 % of men in the United States already have tattoos. However, tattoos often become a personal regret. As recent surveys suggest, 17 % of people that have obtained a tattoo and more than 50 % of adults over the age of 40 in the United States of America consider having them removed. The same trend can be observed in our country as well. Laser therapy is the gold standard for tattoo removal. In Slovenia, laser tattoo removal therapy is available and widely accessible. There is a wide range of facilities offering laser tattoo removal, ranging from different private clinics to beauty salons. Different facilities use different lasers, but not all lasers, however, are optimal for successful and complete tattoo removal, as inappropriate use can cause many unwanted side effects.Methods: Eleven (11 patients (2 men and 9 women requesting tattoo removal were treated in our department. When treating our patients, we used Fotona’s QX MAX quality-switched Nd:YAG laser which offers four different wavelengths in a single system; 1064 nm Nd:YAG was used to treat and remove dark pigments, 532 nm KTP for red, tan-colored, purple and orange tattoo inks, 650 nm dye for green tattoo inks and 585 nm dye for sky-blue colored inks.Results: Satisfactory tattoo removal was achieved in all patients treated. Patients were very satisfied with the success and the number of treatments needed for tattoo removal. There were mild unwanted side effects and the pain was moderate. The average number of treatments required for complete tattoo removal was less than 7, ranging from 3 to 21 treatments. Patients’ satisfaction with tattoo removal was estimated at 5.2 (on a scale from 1 to 6.Conclusions: Our study showed that Q-switched lasers successfully remove tattoo ink, however several treatments are required for satisfactory tattoo removal

  4. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG.......We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  5. Numerical modelling of passively Q-switched intracavity Raman lasers

    International Nuclear Information System (INIS)

    Ding Shuanghong; Zhang Xingyu; Wang Qingpu; Zhang Jun; Wang Shumei; Liu Yuru; Zhang Xuehui


    Assuming intracavity photon densities to be of Gaussian spatial distributions, the space-dependent rate equations of passively Q-switched intracavity Raman lasers are deduced for the first time for the pumping beams of Gaussian and top-head spatial distributions, respectively. The new rate equations are normalized and solved numerically to investigate the influences of the normalized initial population inversion density, normalized Raman gain coefficient, saturable absorber parameter, beam size ratio of pump to fundamental laser and loss ratio of the first Stokes to fundamental laser on the pulse parameters of the first Stokes. The results of the Gaussian and top-head pumpings show similar trends despite some discrepancies. The new theories and numerical results will help design passively Q-switched intracavity Raman lasers of high performance

  6. Narrow Q-switching pulse width and low mode-locking repetition rate Q-switched mode locking with a new coupled laser cavity

    International Nuclear Information System (INIS)

    Peng, J Y; Zheng, Y; Shen, J P; Shi, Y X


    An original diode-pumped Q-switched and mode-locked solid state Nd:GdVO 4 laser is demonstrated. The laser operates with double saturable absorbers and a new coupled laser cavity. The Q-switching envelope width is compressed to be about 15 ns and the mode-locking repetition rate is as low as 90 MHz. (paper)

  7. Tattoo removal by Q-switched yttrium aluminium garnet laser

    DEFF Research Database (Denmark)

    Hutton Carlsen, K; Esmann, J; Serup, J


    BACKGROUND: Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. OBJECTIVE: To determine clients' satisfaction with tattoo removal. METHODS: One hundred and fifty-four tattoo removal clients who had...... relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate...

  8. Removal of Tattoos by Q-Switched Nanosecond Lasers. (United States)

    Karsai, Syrus


    Tattoo removal by Q-switched nanosecond laser devices is generally a safe and effective method, albeit a time-consuming one. Despite the newest developments in laser treatment, it is still not possible to remove every tattoo completely and without complications. Incomplete removal remains one of the most common challenges. As a consequence, particular restraint should be exercised when treating multicoloured tattoos, and patients need to be thoroughly informed about remaining pigment. Other frequent adverse effects include hyper- and hypopigmentation as well as ink darkening; the latter is particularly frequent in permanent make-up. Scarring is also possible, although it is rare when treatment is performed correctly. It is becoming more widespread for laser operators to encounter allergic reactions and even malignant tumours in tattoos, and treating these conditions requires a nuanced approach. © 2017 S. Karger AG, Basel.

  9. Graphene Q-Switched Compact Yb:YAG Laser

    Czech Academy of Sciences Publication Activity Database

    Serres, J.M.; Jambunathan, Venkatesan; Mateos, X.; Loiko, P.; Lucianetti, Antonio; Mocek, Tomáš; Yumashev, K.; Petrov, V.; Griebner, U.; Aguilo, M.; Diaz, F.


    Roč. 7, č. 5 (2015), s. 1-8, č. článku 1503307. ISSN 1943-0655 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : graphene * saturable absorber * Q-switched laser Subject RIV: BH - Optics, Masers, Laser s OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 2.177, year: 2015

  10. Passive Fe2+ : ZnSe single-crystal Q switch for 3-mu m lasers

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Polushkin, VG; Frolov, MP

    Passive Q-switching of 3-mu m lasers with the help of a Fe2+ : ZnSe single crystal is demonstrated. The 6-mJ, 50-ns giant pulses are obtained from a 2.9364-mu m Er : YAG laser by using this passive Q switch.

  11. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal. (United States)

    Radmanesh, Mohammad; Rafiei, Zohreh


    The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

  12. Q-Switched High Power Single Frequency 2 Micron Fiber Laser, Phase I (United States)

    National Aeronautics and Space Administration — Accurate measurement of atmospheric parameters with high resolution needs advanced lasers. In this SBIR program we propose to develop innovative Q-switched high...

  13. Q-switched oscillation in thulium-doped fiber lasers using preloaded dynamic microbending technique (United States)

    Sakata, H.; Takahashi, N.; Ushiro, Y.


    We demonstrate Q-switched pulse generation in thulium-doped fiber lasers by introducing piezoelectric-driven microbend with preloaded stress. We employed a pair of corrugated chips each attached on piezoelectric actuators (PAs) to clamp the fiber in a ring laser resonator. The thulium-doped fiber is pumped by a laser diode emitting at 1.63 μm and generates the Q-switched laser pulses at around 1.9 μm by switching off the PAs. The laser pulse performance is improved by optimizing the preload and switch-off period for the PAs. The Q-switched pulses with a peak power of 2.8 W and a pulsewidth of 900 ns are observed for a launched pump power of 161 mW. We expect that the in-fiber Q-switching technique will provide efficient laser systems for environmental sensing and medical applications.

  14. Treatment of Large Bulla Formation after Tattoo Removal with a Q-Switched Laser (United States)

    Kartono, Francisca; Desai, Alpesh; Kaur, Ravneet R.; Desai, Tejas


    Widely considered the gold standard treatment option for tattoo removal, the use of Q-switched lasers may very rarely result in the formation of large bulla. While very disconcerting to patients, these lesions are easily managed and, with proper care, heal quickly with no long-term consequences. The authors present three cases of patients who had bullous reactions shortly after receiving Q-switched laser treatment of tattoo ink. Bullous formation in all three patients was treated successfully. PMID:20725537


    Directory of Open Access Journals (Sweden)



    Full Text Available This paper is the first of a four series treating, theoretically with experimental comparison, the issue of solid state laser passive optical Q-switching regime. In this first paper the technique of solid state lasers passive optical Q-switching is numerically investigated considering the case of longitudinally and transversally uniform photon, population inversion and absorption centres densities. The coupled differential equations defining photon, population inversion and absorption centres densities are numerically solved being the basis of passively optical Q-switched laser functional simulation. The numerical simulations are performed using the several software packages, mostly SCILAB programs. The developed SCILAB programs can be used for a large range of saturable absorption centre and active media parameters, mainly the initial (low signal optical transmittance of the passive optical Q-switch. The developed FORTRAN and SCILAB programs can be applied for passively Q-switched solid state lasers of several types emitting at several NIR wavelengths, in domain 1 ÷ 2 μm. For validating the numerical simulation results are compared with The results of the numerical simulation are compared with experimentally obtained ones, in the case of a LiF:F2- passively Q-switched Nd:YAG. A good agreement between the two kinds of results is observed.

  16. Tungsten disulphide based all fiber Q-switching cylindrical-vector beam generation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.; Yan, K.; Zhou, Y. [Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei 230026 (China); Xu, L. X., E-mail:; Gu, C. [Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei 230026 (China); Haixi Collaborative Innovation Center for New Display Devices and Systems Integration, Fuzhou University, Fuzhou 350002 (China); Zhan, Q. W. [Electro-Optics Program, University of Dayton, Dayton, Ohio 45469 (United States)


    We proposed and demonstrated an all fiber passively Q-switching laser to generate cylindrical-vector beam, a two dimensional material, tungsten disulphide (WS{sub 2}), was adopted as a saturable absorber inside the laser cavity, while a few-mode fiber Bragg grating was used as a transverse mode-selective output coupler. The repetition rate of the Q-switching output pulses can be varied from 80 kHz to 120 kHz with a shortest duration of 958 ns. Attributed to the high damage threshold and polarization insensitivity of the WS{sub 2} based saturable absorber, the radially polarized beam and azimuthally polarized beam can be easily generated in the Q-switching fiber laser.

  17. Nanosecond Q-switched operation of coupled Yb and Tm fibre lasers

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, Yuen H [Laser Photonics Research Group, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Qamar, Fadi [Laser Photonics Research Group, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); King, Terence A [Laser Photonics Research Group, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Ko, Do-Kyeong [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-Gu, Gwangju 500-712 (Korea, Republic of); Lee, Jongmin [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-Gu, Gwangju 500-712 (Korea, Republic of)


    A small scale coupled Yb-silica and Tm-silica fibre laser system is described with output at 1.9 {mu}m and with Q-switching using an acousto-optic modulator and also by mechanical optical modulation. The Yb-fibre laser pump source exhibited strong self-pulsation with high-intensity pulses due to stimulated Brillouin scattering. But regular Q-switched pulses were generated from the Tm-fibre laser with an energy of {approx}2.4 {mu}J and duration (FWHM) of {approx}280 ns for modulation frequencies of 1-20 kHz when using acousto-optic modulation. The main effects that limit the Q-switched pulse peak power are the onset of gain-switched pulsing during the low-Q state and strong pump excited state absorption.

  18. A Q-Switched Erbium-Doped Fiber Laser with a Carbon Nanotube Based Saturable Absorber

    International Nuclear Information System (INIS)

    Harun, S. W.; Ismail, M. A.; Ahmad, F.; Ismail, M. F.; Nor, R. M.; Zulkepely, N. R.; Ahmad, H.


    We demonstrate a simple, compact and low cost Q-switched erbium-doped fiber laser (EDFL) using single-wall carbon nanotubes (CNTs) as a saturable absorber for possible applications in metrology, sensing, and medical diagnostics. The EDFL operates at around 1560 nm with repetition rates of 16.1 kHz and 6.4 kHz with saturable absorbers SA1 and SA2 at a pump power of 120 mW. The absorbers are constructed by optically driven deposition and normal deposition techniques. It is observed that the optical deposition method produces a Q-switched EDFL with a lower threshold of 70 mW and better Q-switching performance compared to that of the normal deposition method. The EDFL also has pulse energy of 90.3 nJ and pulse width of 11.6 μs at 120 mW pump power

  19. Synchronisation of a femtosecond laser and a Q-switched laser to within 50 ps

    International Nuclear Information System (INIS)

    Katin, E V; Lozhkarev, V V; Palashov, O V; Khazanov, E A


    A Nd:YLF laser emitting 2-ns pulses synchronised with a femtosecond Cr:forsterite laser is built. The pulse duration and synchronisation are ensured by two Pockels cells, in which voltage pulses are synchronised with the femtosecond laser by fast emitter-coupled logic elements. One of the Pockels cells ensures Q-switching, while the other cuts a short pulse from a 15-ns Q-switched pulse. The experimental results show that the two-step scheme proposed for synchronisation of a Q-switched laser and a passively mode-locked laser provides quite simple and reliable synchronisation of these lasers with a jitter of a few tens of picoseconds. (control of laser radiation parameters)

  20. Metal impurity injection into DIVA plasmas with a Q-switched laser beam

    International Nuclear Information System (INIS)

    Yamauchi, Toshihiko; Nagami, Masayuki; Sengoku, Seio; Kumagai, Katsuaki


    Metal impurity injection into DIVA plasmas with a Q-switched ruby laser beam is described. Metal materials used are aluminium and gold. The Q-switched laser beam is incident onto a thin metal film thickness about 0.2 μm coated on pyrex glass plate surface. The metal film is vaporized by the laser beam and injected into DIVA plasma. The laser-beam injection method has advantages of sharp profile of vaporized metal, easy control of vaporized metal quantity and injection rate control of metal vapor. (author)

  1. Design of a high-power Nd:YAG Q-switched laser cavity (United States)

    Singh, Ikbal; Kumar, Avinash; Nijhawan, O. P.


    An electro-optically Q-switched Nd:YAG laser resonator that uses two end prisms placed orthogonally perpendicular to each other has been designed. This configuration improves the stability of the resonator and does not alter the characteristics of the electro-optical Q switch. The outcoupling ratio of the cavity is optimized by a change in the azimuthal angle of a phase-matched Porro prism placed at one end of the cavity. The prism placed at the other end of the cavity is designed so that it introduces a phase change of Pi , regardless of its orientation and index of refraction, resulting in a more efficient and stable cavity.

  2. Compact frequency-modulation Q-switched single-frequency fiber laser at 1083 nm

    International Nuclear Information System (INIS)

    Zhang, Yuanfei; Feng, Zhouming; Xu, Shanhui; Mo, Shupei; Yang, Changsheng; Li, Can; Gan, Jiulin; Chen, Dongdan; Yang, Zhongmin


    A compact frequency-modulation Q-switched single-frequency fiber laser is demonstrated at 1083 nm. The short linear resonant cavity consists of a 12 mm long homemade Yb 3+ -doped phosphate fiber and a pair of fiber Bragg gratings (FBGs) in which the Q-switching and the frequency excursion is achieved by a tensile-induced period modulation. Over 375 MHz frequency-tuning range is achieved with a modulation frequency varying from tens to hundreds of kilohertz. The highest peak power of the output pulse reaching 6.93 W at the repetition rate of 10 kHz is obtained. (paper)

  3. Compact self-Q-switched Tm:YLF laser at 1.91 μm (United States)

    Zhang, B.; Li, L.; He, C. J.; Tian, F. J.; Yang, X. T.; Cui, J. H.; Zhang, J. Z.; Sun, W. M.


    We report self-Q-switching operation in a diode-pumped Tm:YLF bulk laser by exploiting saturable re-absorption under the quasi-three-level regime. Robust self-Q-switched pulse output at 1.91 μm in fundamental mode is demonstrated experimentally with 1.5 at.% doped Tm:YLF crystal. At maximum absorbed pump power of 4.5 W, the average output power and pulse energy are obtained as high as 610 mW and 29 μJ, respectively, with the corresponding slope efficiency of 22%. Pulse repetition rate is tunable in the range of 3-21 kHz with changing the pump power. The dynamics of self-Q-switching of Tm:YLF laser are discussed with the help of a rate equation model showing good agreement with the experiment. The compact self-Q-switched laser near 2 μm has potential application in laser radar systems for accurate wind velocity measurements.

  4. Optimization of an intracavity Q-switched solid-state second order Raman laser (United States)

    Chen, Zhiqiong; Fu, Xihong; Peng, Hangyu; Zhang, Jun; Qin, Li; Ning, Yongqiang


    In this paper, the model of an intracavity Q-switched second order Raman laser is established, the characteristics of the output 2nd Stokes are simulated. The dynamic balance mechanism among intracavity conversion rates of stimulated emission, first order Raman and second order Raman is obtained. Finally, optimization solutions for increasing output 2nd Stokes pulse energy are proposed.

  5. Optimization of end-pumped, actively Q-switched quasi-III-level lasers. (United States)

    Jabczynski, Jan K; Gorajek, Lukasz; Kwiatkowski, Jacek; Kaskow, Mateusz; Zendzian, Waldemar


    The new model of end-pumped quasi-III-level laser considering transient pumping processes, ground-state-depletion and up-conversion effects was developed. The model consists of two parts: pumping stage and Q-switched part, which can be separated in a case of active Q-switching regime. For pumping stage the semi-analytical model was developed, enabling the calculations for final occupation of upper laser level for given pump power and duration, spatial profile of pump beam, length and dopant level of gain medium. For quasi-stationary inversion, the optimization procedure of Q-switching regime based on Lagrange multiplier technique was developed. The new approach for optimization of CW regime of quasi-three-level lasers was developed to optimize the Q-switched lasers operating with high repetition rates. Both methods of optimizations enable calculation of optimal absorbance of gain medium and output losses for given pump rate. © 2011 Optical Society of America

  6. Passive Q switching of a solar-pumped Nd:YAG laser. (United States)

    Lando, M; Shimony, Y; Noter, Y; Benmair, R M; Yogev, A


    Passive Q switching is a preferable choice for switching the Q factor of a solar-pumped laser because it requires neither a driver nor an electrical power supply. The superior thermal characteristics and durability of Cr(4+):YAG single crystals as passive Q switches for lamp and diode-pumped high-power lasers has been demonstrated. Here we report on an average power of 37 W and a switching efficiency of 80% obtained by use of a solar-pumped Nd:YAG laser Q switched by a Cr(4+):YAG saturable absorber. Concentration of the pumping solar energy on the laser crystal was obtained with a three-stage concentrator, composed of 12 heliostats, a three-dimensional compound parabolic concentrator (CPC) and a two-dimensional CPC. The water-cooled passive Q switch also served as the laser rear mirror. Repetition rates of as much as 50 kHz, at pulse durations between 190 and 310 ns (FWHM) were achieved. From the experimental results, the saturated single-pass power absorption of the Cr(4+):YAG device was estimated as 3 ? 1%.

  7. Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser

    NARCIS (Netherlands)

    Klein, M.E.; Adel, P.; Auerbach, M.; Fallnich, C.; Gross, P.; Boller, Klaus J.


    We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-ms-long pulses from an actively Q-switched

  8. High repetition rate, high energy, actively Q-switched all-in-fiber laser (United States)

    Lecourt, J. B.; Bertrand, A.; Guillemet, S.; Hernandez, Y.; Giannone, D.


    We report an actively Q-switched Ytterbium-doped all-in-fibre laser delivering 10ns pulses with high repetition rate (from 100kHz to 1MHz). The laser operation has been validated at three different wavelengths (1040, 1050 and 1064nm). The laser can deliver up to 20Watts average power with an high beam quality (M2 = 1).

  9. Diode array pumped, non-linear mirror Q-switched and mode-locked

    Indian Academy of Sciences (India)

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while ...

  10. Diode-pumped Alexandrite laser with passive SESAM Q-switching and wavelength tunability (United States)

    Parali, Ufuk; Sheng, Xin; Minassian, Ara; Tawy, Goronwy; Sathian, Juna; Thomas, Gabrielle M.; Damzen, Michael J.


    We report the first experimental demonstration of a wavelength tunable passively Q-switched red-diode-end pumped Alexandrite laser using a semiconductor saturable absorber mirror (SESAM). We present the results of the study of passive SESAM Q-switching and wavelength-tuning in continuous diode-pumped Alexandrite lasers in both linear cavity and X-cavity configurations. In the linear cavity configuration, pulsed operation up to 27 kHz repetition rate in fundamental TEM00 mode was achieved and maximum average power was 41 mW. The shortest pulse generated was 550 ns (FWHM) and the Q-switched wavelength tuning band spanned was between 740 nm and 755 nm. In the X-cavity configuration, a higher average power up to 73 mW, and obtained with higher pulse energy 6 . 5 μJ at 11.2 kHz repetition rate, in fundamental TEM00 mode with excellent spatial quality M2 < 1 . 1. The Q-switched wavelength tuning band spanned was between 775 nm and 781 nm.

  11. Q-switched Ho:YLF laser pumped by a Tm:GdVO4 laser.

    CSIR Research Space (South Africa)

    Esser, MJD


    Full Text Available The authors have, through careful analysis of spectroscopic data, designed and demonstrated a diode-end-pumped, quasicontinuous wave Tm:GdVO4 laser operating at 1892 nm in order to pump a Q-switched Ho:YLF laser. The Ho:YLF maximum output energy...

  12. Passive synchronized Q-switching between a quasi-three-level and a four-level laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Tidemand-Lichtenberg, Peter; Jensen, Ole Bjarlin


    Synchronized Q-switching between quasi-three-level and four-level lasers is interesting for sum-frequency generation into the blue and ultraviolet. We report, for the first time, stable synchronized Q-switching between a quasi-three-level laser at 946 nm and a four-level laser at 1064 nm in an all...

  13. High average power 1314 nm Nd:YLF laser, passively Q-switched with V:YAG

    CSIR Research Space (South Africa)

    Botha, RC


    Full Text Available A 1314 nm Nd:YLF laser was designed and operated both CW and passively Q-switched. Maximum CW output of 10.4 W resulted from 45.2 Wof incident pump power. Passive Q-switching was obtained by inserting a V:YAG saturable absorber in the cavity...

  14. Laser-tissue interaction in tattoo removal by q-switched lasers. (United States)

    Barua, Shyamanta


    Q-switched (QS) lasers are widely considered the gold standard for tattoo removal, with excellent clinical results, impressive predictability, and a good safety profile. The generation of giant pulses by the method of Q-switching is responsible for the unique laser-tissue interaction that is seen in tattoo removal by QS lasers. The QS lasers work by impaction and dissolution of the tattoo pigments. Mechanical fragmentation of the tattoo pigments encased in intracellular lamellated organelles followed by their phagocytosis by macrophages is thought to be the major event in the clearance of pigments by QS lasers. A few novel techniques have been tried in recent times to hasten the clearance of tattoo pigments.

  15. Black phosphorus saturable absorber for Q-switched Er:YAG laser at 1645 nm (United States)

    Guo, Lei; Li, Tao; Zhang, Shuaiyi; Wang, Mingjian; Yang, Kejian; Fan, Mingqi; Zhao, Shengzhi; Li, Ming


    A Q-switched Er:YAG solid-state laser at 1645 nm based on black phosphorus (BP) saturable absorbers (SAs) was demonstrated firstly to our knowledge. The BP-SA was fabricated by drop-casting BP nanoplatelets dispersion on a YAG substrate and corresponding saturable absorption properties were characterized at 1.6 μm. By employing as-prepared BP-SAs, stable Q-switched laser operations were achieved with a pulse width of 2.8 μs and a repetition rate of 34 kHz, corresponding to the average output power of 0.33 W. The results verify that BP-SAs have great potential for pulsed 1.6 μm lasers.

  16. Q-switched operation with Fox-Smith-Michelson laser cavity

    International Nuclear Information System (INIS)

    Huang, X; Huang, L; Gong, M


    A new kind of three-mirror composite cavity, Fox-Smith-Michelson cavity has been configured. This laser cavity is capable of high power output, owing to the low threshold of Michelson cavity. Also, thanks to the mode selection function of Fox-Smith cavity, stable pulses at high repetition rate can be generated. In our experiment, 15.54 W CW output at 1064 nm has been achieved, with an optic-to-optic conversion efficiency of 42.2%. At the Q-switching repetition rate of 100 kHz, the average output power is 11.92 W, with an optic-to-optic conversion efficiency of 38.2%. For Q-switching frequency from 30 kHz to 100 kHz, the pulse width variation is below 4.4% and the amplitude variation is below 4.8%

  17. Self-Q-switched ytterbium-doped cladding-pumped fibre laser

    International Nuclear Information System (INIS)

    Grukh, Dmitrii A; Kurkov, Andrei S; Razdobreev, I M; Fotiadi, A A


    A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied. (solitons and optical fibers)

  18. Q-switched pulse laser generation from double-cladding Nd:YAG ceramics waveguides. (United States)

    Tan, Yang; Luan, Qingfang; Liu, Fengqin; Chen, Feng; Vázquez de Aldana, Javier Rodríguez


    This work reports on the Q-switched pulsed laser generation from double-cladding Nd:YAG ceramic waveguides. Double-cladding waveguides with different combination of diameters were inscribed into a sample of Nd:YAG ceramic. With an additional semiconductor saturable absorber, stable pulsed laser emission at the wavelength of 1064 nm was achieved with pulses of 21 ns temporal duration and ~14 μJ pulse energy at a repetition rate of 3.65 MHz.

  19. Vibrating mirror system suitable for q-switching large-aperture lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beckwith, P.J.


    Resonant vibrating mirrors provide a convenient means of Q-switching a laser, but large-aperture versions require careful design if the drive power is not to become excessive. This report outlines the design principles involved in the optimisation of moving-iron galvanometer drivers, and describes a prototype device with an aperture of 40 mm x 80 mm which is capable of beam deflections of + or - 40 mrad at 800 Hz. Some suggestions are made concerning more refined designs.

  20. Stabilization of the quasi-periodic motion of a Q-switched Nd:YAG laser

    International Nuclear Information System (INIS)

    Kim, Chil-Min; Rim, Sunghwan; Kye, Won-Ho; Kim, Jeong-Moog; Lee, Kang-Soo


    We have developed a stabilization method of quasi-periodicity based on a return map. The method is explained in the forced Van der Pol oscillator, and applied experimentally to a quasi-periodic output of a Q-switched Nd:YAG laser. Even though the attractors have no unstable periodic orbit, we were able to stabilize them to an arbitrarily chosen orbit by targeting the trajectory into it

  1. High average power Q-switched 1314 nm two-crystal Nd:YLF laser

    CSIR Research Space (South Africa)

    Botha, RC


    Full Text Available . 40, No. 4 / OPTICS LETTERS High average power Q-switched 1314 nm two-crystal Nd:YLF laser R. C. Botha,1,2,* W. Koen,3 M. J. D. Esser,3,4 C. Bollig,3,5 W. L. Combrinck,1,6 H. M. von Bergmann,2 and H. J. Strauss3 1HartRAO, P.O. Box 443...

  2. Development of the RTP crystal applications for Q-switching operation and second harmonics generation

    International Nuclear Information System (INIS)

    Alnayli, R.Sh.


    Complete text of publication follows. A dialed theoretical studies on performances of the ideal RTP crystal for the electro optical applications as Q-switching laser operation and for nonlinear optics application as second harmonics generation are accomplished in this paper. Single or pair RTP crystal of excellent quality with dimensions 5 x 5 x 7.5 mm 3 have proposed as element model to combined Q-switching operation and frequency doublers for 1.06 μm wave length laser. In order to get and interpolate the optimum conditions to combined both of these operations by application this RTP model. The main am of this work was investigated the most influent parameters on the performance of the electro optical Q-switching laser operation such as, the voltage requirement, contrast and extinction ratios, the birefringence effective and withstand threshold on the other hand the influences of the ray walk off, thermal effective on the efficiency of the second harmonics generation as well are investigated. The results were satisfied for the goals of this paper.

  3. Efficient 2-μm Tm:YAP Q-switched and CW lasers (United States)

    Hays, A. D.; Cole, Brian; King, Vernon; Goldberg, Lew


    Highly efficient, diode pumped Tm:YAP lasers generating emission in the 1.85-1.94 μm range are demonstrated and characterized. Laser optical efficiencies of 51% and 45%, and electrical efficiencies of 31% and 25% are achieved under CW and Q-switched operation, respectively. Laser performance was characterized for maximum average powers up to 20W with various cavity configurations, all using an intra-cavity lens to compensate for thermal lensing in the Tm:YAP crystal. Q-switched lasers incorportating a Cr:ZnS saturable absorber (SA), resonant mechanical mirror scanner, or acousto-optic modulator were characterized. To enable higher average output powers, measurements of the thermal lens were conducted for the Tm:YAP crystal as a function of pump power and were compared to values predicted by a finiteelement- analysis (FEA) thermal-optical model of the Tm:YAP crystal. A resonator model is developed to incorporate this calculated thermal lens and its effect on laser performance. This paper will address approaches for improving the performance of Tm:YAP lasers, and means for achieving increased average output powers while maintaining high optical efficiency for both SA and mechanical Q-switching.

  4. Submicrosecond Q-Switching Er-Doped All-Fiber Ring Laser Based on Black Phosphorus

    Directory of Open Access Journals (Sweden)

    Yao Cai


    Full Text Available Black phosphorus (BP, a new two-dimensional (2D material, has been deeply developed for extensive applications in electronics and optoelectronics due to its similar physical structure to graphene and thickness dependent direct band gap. Here, we demonstrated a submicrosecond passive Q-switching Er-doped fiber laser with BP as saturable absorber (SA. The BP saturable absorber was fabricated by mechanical exfoliation method. By taking full advantage of the ultrafast relaxation time of BP-SA and careful design of compact ring cavity, we obtained stable Q-switching pulses output with a shortest duration as narrow as 742 ns. With increasing the pump power, the pulse repetition rate accreted gradually almost linearly from 9.78 to 61.25 kHz, and the pulse duration declined rapidly at lower pump power regime and retained approximate stationary at higher pump power regime from 3.05 to 0.742 μs. The experimental results indicate that BP-SA can be an effective SA for nanosecond Q-switching pulse generation.

  5. Depigmentation therapy with Q-switched Nd: YAG laser in universal vitiligo

    Directory of Open Access Journals (Sweden)

    Imran Majid


    Full Text Available Background: Any residual pigment left in patients of universal vitiligo is managed with topical treatments, cryotherapy, and lasers. Aim: The study aims to assess the efficacy and safety of Q-switched Nd: YAG laser in treating the residual pigmentation in patients with universal vitiligo. Materials and Methods: Fifteen patients of universal vitiligo with residual pigmentation on the face, hands, or feet, resistant to topical treatments, were treated with single or multiple sessions of Q-switched Nd: YAG laser treatment. Topical treatments were continued in between the laser sessions and the depigmentation achieved was monitored by clinical examination and repeat digital photographs. Response to the treatment was labelled as excellent if the residual pigment could be reduced by at least 90% while 50-90% resolution of pigmentation was labelled as a partial response. Adverse effects to the treatment offered were also monitored. Results: Thirteen of the 15 patients enrolled for the study showed an excellent response to the treatment offered. Two other patients showed a poor response with less than 50% resolution of pigmentation. The number of laser sessions needed at a particular site ranged from 1 to 3 and no patient was offered more than three sessions of laser treatment at any site. No significant adverse events were reported by any patient. Conclusions: Residual pigmentation in patients with universal vitiligo that does not respond to topical treatment options alone can be managed quite effectively with Q-switched Nd: YAG laser without any significant adverse effects.

  6. All-fibre Q-switching YDFL operation with bismuth-doped fibre as saturable absorber (United States)

    Muhammad, A. R.; Haris, H.; Arof, H.; Tan, S. J.; Ahmad, M. T.; Harun, S. W.


    We demonstrate the generation of a passively Q-switched ytterbium-doped fibre laser (YDFL) using a bismuth-doped fibre (BDF) as a solid-state fibre saturable absorber (FSA) in a ring cavity. The BDF used has a wide and low absorption band of 5 dB/m at the 1.0 μm region due to the ion transition of ? that occurs around the region. When introduced into a YDFL laser cavity, a stable Q-switched pulse operation was observed and the pulse repetition rate was proportional to the input pump power. It was limited to 72.99 kHz by the maximum power that the laser diode could supply. Meanwhile, the pulse width decreased from 12.22 to 4.85 μs as the pump power was increased from 215.6 to 475.6 mW. The finding suggests that BDF could be used as a potential SA for the development of robust, compact, efficient and low cost Q-switched fibre lasers operating at 1 micron region.

  7. Self-Q-switching behavior of erbium-doped tellurite microstructured fiber lasers

    International Nuclear Information System (INIS)

    Jia, Zhi-Xu; Yao, Chuan-Fei; Kang, Zhe; Qin, Guan-Shi; Qin, Wei-Ping; Ohishi, Yasutake


    We reported self-Q-switching behavior of erbium-doped tellurite microstructured fiber (EDTMF) lasers and further demonstrated a self-Q-switched EDTMF laser with a high repetition rate of more than 1 MHz. A 14 cm EDTMF was used as the gain medium. Upon a pump power of ∼705 mW at 1480 nm, output pulses with a lasing wavelength of ∼1558 nm, a repetition rate of ∼1.14 MHz, and a pulse width of ∼282 ns were generated from the fiber by employing a linear cavity. The maximum output power was ∼316 mW and the slope efficiency was about 72.6% before the saturation of the laser power. Moreover, the influence of the fiber length on laser performances was investigated. The results showed that self-Q-switching behavior in our experiments was caused by the re-absorption originated from the ineffectively pumped part of the active fiber.

  8. Efficient in-band diode-pumped Q-switched solid state laser for methane detection, Phase II (United States)

    National Aeronautics and Space Administration — We propose to develop an efficient, tunable Q-switched SSL operating at a wavelength of 1651 nm with pulse energy >1 mJ at 2000 Hz repetition rate with in-band...

  9. Nanosecond-pulsed Q-switched Nd:YAG laser at 1064 nm with a gold nanotriangle saturable absorber (United States)

    Chen, Xiaohan; Li, Ping; Dun, Yangyang; Song, Teng; Ma, Baomin


    Gold nanotriangles (GNTs) were successfully employed as a saturable absorber (SA) to achieve passively Q-switched lasers for the first time. The performance of the Q-switched Nd:YAG laser at 1064 nm has been systematically investigated. The corresponding shortest pulsewidth, the threshold pump power and the maximum Q-switched average output power were 275.5 ns, 1.37 W, and 171 mW, respectively. To our knowledge, this is the shortest pulsewidth and the lowest threshold in a passively Q-switched laser at approximately 1.1 µm based on a gold nanoparticle SA (GNPs-SA). Our experimental results proved that the GNTs-SA can be used as a promising saturable absorber for nanosecond-pulsed lasers.

  10. Efficient energy extraction from a diode-pumped Q-switched Tm,Ho:YLiF4 laser (United States)

    Mcguckin, B. T.; Menzies, R. T.; Hemmati, H.


    The operation of a diode-laser pumped thulium, holmium yttrium-lithium-fluoride laser (Tm,Ho:YLF) in Q-switched mode is reported. Output energies of 200 microjoules in pulses of 22 ns duration are recorded at Q-switch frequencies commensurate with an effective upper laser level lifetime of 6 ms. This lifetime is appreciably longer than that observed in other hosts permitting stored energy extraction of 64 percent, close to the projected maximum performance from these materials.

  11. Pigmented guinea pig skin irradiated with Q-switched ruby laser pulses. Morphologic and histologic findings

    Energy Technology Data Exchange (ETDEWEB)

    Dover, J.S.; Margolis, R.J.; Polla, L.L.; Watanabe, S.; Hruza, G.J.; Parrish, J.A.; Anderson, R.R.


    Q-switched ruby laser pulses cause selective damage to cutaneous pigmented cells. Repair of this selective damage has not been well described. Therefore, using epilated pigmented and albino guinea pig skin, we studied the acute injury and tissue repair caused by 40-ns, Q-switched ruby laser pulses. Gross observation and light and electron microscopy were performed. No specific changes were evident in the albino guinea pigs. In pigmented animals, with radiant exposures of 0.4 J/cm2 or greater, white spots confined to the 2.5-mm exposure sites developed immediately and faded over 20 minutes. Delayed depigmentation occurred at seven to ten days, followed by full repigmentation by four to eight weeks. Regrowing hairs in sites irradiated at and above 0.4 J/cm2 remained white for at least four months. Histologically, vacuolation of pigment-laden cells was seen immediately in the epidermis and the follicular epithelium at exposures of 0.3 J/cm2 and greater. Melanosomal disruption was seen immediately by electron microscopy at and above 0.3 J/cm2. Over the next seven days, epidermal necrosis was followed by regeneration of a depigmented epidermis. By four months, melanosomes and melanin pigmentation had returned; however, hair follicles remained depigmented and devoid of melanocytes. This study demonstrates that selective melanosomal disruption caused by Q-switched ruby laser pulses leads to transient cutaneous depigmentation and persistent follicular depigmentation. Potential exists for selective treatment of pigmented epidermal and dermal lesions with this modality.

  12. Experimental study of a Q-switched ytterbium-doped double-clad fiber laser

    International Nuclear Information System (INIS)

    Anzueto S, G.; Estudillo A, M.; Martinez R, A.; Torres G, I.; Selvas A, R.


    We report an experimental characterization of a Q-switched operation of an all-fiber laser using , 30 m of a double-clad ytterbium-doped fiber spliced to a piece of single-mode un-doped holey fiber. Loss modulation in the splicing point between the active and un-doped fiber due to a substantial coupling of light into lossy cladding modes stimulates pulsed operation of the fiber laser. Pulse energy of ∼2.5 μJ was estimated and the repetition rate was measured in the range of 4-16 KHz. (Author)

  13. Graphene Oxide-Based Q-Switched Erbium-Doped Fiber Laser

    International Nuclear Information System (INIS)

    Yap, Y. K.; Harun, S. W.; Ahmad, H.; Huang, N. M.


    We demonstrate a pulsed ring erbium-doped fiber laser based on graphene oxide (GO), employing a simplified Hummer's method to synthesize the GO via chemical oxidation of graphite flakes at room temperature. By dipping a fiber ferrule end face onto the GO suspension, GO is successfully coated onto the end face, making it a simple saturable absorption device. A stable Q-switched pulsed fiber laser is achieved with a low pump threshold of 9.5 mW at 980 nm. The pulse repetition rate ranges from 16.0 to 57.0 kHz. The pulse width and the pulse energy are studied and discussed

  14. A highly efficient graphene oxide absorber for Q-switched Nd:GdVO4 lasers

    International Nuclear Information System (INIS)

    Wang Yonggang; Wen Xiaoming; Tang Jau; Chen, Hou Ren; Hsieh, Wen Feng


    We demonstrated that graphene oxide material could be used as a highly efficient saturable absorber for the Q-switched Nd:GdVO 4 laser. A novel and low-cost graphene oxide (GO) absorber was fabricated by a vertical evaporation technique and high viscosity of polyvinyl alcohol (PVA) aqueous solution. A piece of GO/PVA absorber, a piece of round quartz, and an output coupler mirror were combined to be a sandwich structure passive component. Using such a structure, 104 ns pulses and 1.22 W average output power were obtained with the maximum pulse energy at 2 µJ and a slope efficiency of 17%.

  15. Development of laser marking system with electro-optic Q-switch

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon.


    We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs

  16. Development of laser marking system with electro-optic Q-switch

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon


    We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs.

  17. An injection seeded single frequency Nd:YAG Q-switched laser with precisely controllable laser pulse firing time (United States)

    Wu, Frank F.; Khizhnyak, Anatoliy; Markov, Vladimir


    We have realized a single frequency Q-switched Nd:YAG laser with precisely controllable lasing time and thus enabled synchronization of multi-laser systems. The use of injection seeding to the slave ring oscillator results in unidirectional Q-switched laser oscillation with suppression of bidirectional Q-switched oscillation that otherwise would be initiated from spontaneous emission if the seeding laser is not present. Under normal condition, the cavity is high in loss during the pumping period; then a Pockels cell opens the cavity to form the pulse build up, with a second Pockels cell to perform cavity dumping, generating the Q-switched pulse output with optimized characteristics. The two Pockels cells can be replaced by a single unit if an adjustable gated electrical pulse is applied to the Pockels cell in which the pulse front is used to open the cavity and the falling edge to dump the laser pulse. Proper selection of the pump parameters and Pockels-cell gating enables operation of the system in a mode in which the Q-switched pulse can be formed only under the seeding condition. The advantage of the realized regime is in stable laser operation with no need in adjustment of the seeded light wavelength and the mode of the cavity. It is found that the frequency of the Q-switched laser radiation matches well to the injected seeded laser mode. By using two-stage amplifiers, an output energy better than 300 mJ has been achieved in MOPA configuration without active control of the cavity length and with pulse width adjustability from several nanoseconds to 20 ns. The Q-switched oscillator operates not only at precisely controlled firing time but also can be tuned over wide range. This will enable multi-laser systems synchronization and frequency locking down each other if necessary.

  18. Pure antimony film as saturable absorber for Q-switched erbium-doped fiber laser (United States)

    Rahman, M. F. A.; Zhalilah, M. Z.; Latiff, A. A.; Rosol, A. H. A.; Lokman, M. Q.; Bushroa, A. R.; Dimyati, K.; Harun, S. W.


    This paper reports on the use of Antimony (Sb) polymer film to generate stable Q-switching pulses in Erbium-doped fiber laser (EDFL) cavity. The SA is fabricated by coating a thin layer of Sb on a polyvinyl alcohol (PVA) film through physical vapour deposition (PVD) process. A 1 × 1 mm area of the film SA is cut and integrated into between two fiber ferrules inside the laser cavity for intra-cavity loss modulation. Self-starting and stable Q-switched pulses are obtained within a pump power range from 60 to 142 mW. Within this range, the repetition rate increases from 70.82 to 98.04 kHz, while pulse width decreases from 7.42 to 5.36 μs. The fundamental frequency signal-to-noise ratio of the pulse signal is 74 dB, which indicates the excellent stability of the pulses. The maximum output power and pulse energy are 8.45 mW and 86.19 nJ, respectively. Our demonstration shows that Sb film SA capable of generating stable pulses train operating at 1.55-micron region.

  19. Experimental and Numerical Comparison Q-Switched Fiber Laser Generation using Graphene as Saturable Absorber

    Directory of Open Access Journals (Sweden)

    Awang Noor Azura


    Full Text Available We demonstrated the comparison experimentally and numerically a compact Q-switched erbium-doped fiber (EDF laser based on graphene as a saturable absorber (SA. By optically driven deposition of graphene on a fiber core, the SA is constructed and inserted into a diode-pumped EDF laser cavity. Lasing in CW region starts at 10 mW, whereas stable self-starting Q-switching with a central wavelength of 1530 nm begins at 18 mW. In this paper, at 35 mW, the maximum pulse energy reaches at 2 μJ with pulse repetition rate of 1 MHz and the narrowest pulse width is around 10 μs is obtained. The stability of the pulse is verified from the radio-frequency (RF spectrum with a measured signal-to-noise ratio (SNR of 48 dB. In this study, the design is compared with the simulation using the Optisystem software. The output power of the experimental study is also compared with the simulation to examine the performance.

  20. Q-switched ruby laser irradiation of normal human skin. Histologic and ultrastructural findings. (United States)

    Hruza, G J; Dover, J S; Flotte, T J; Goetschkes, M; Watanabe, S; Anderson, R R


    The Q-switched ruby laser is used for treatment of tatoos. The effects of Q-switched ruby laser pulses on sun-exposed and sun-protected human skin, as well as senile lentigines, were investigated with clinical observation, light microscopy, and transmission electron microscopy. A pinpricklike sensation occurred at radiant exposures as low as 0.2 J/cm2. Immediate erythema, delayed edema, and immediate whitening occurred with increasing radiant exposure. The threshold for immediate whitening varied inversely with skin pigmentation, ranging from a mean of 1.4 J/cm2 in lentigines to 3.1 J/cm2 in sun-protected skin. Transmission electron microscopy showed immediate alteration of mature melanosomes and nuclei within keratinocytes and melanocytes, but stage I and II melanosomes were unaffected. Histologically, immediate injury was confined to the epidermis. There was minimal inflammatory response 1 day after exposure. After 1 week, subthreshold exposures induced hyperpigmentation, with epidermal hyperplasia and increased melanin staining noted histologically. At higher radiant exposures, hypopigmentation occurred with desquamation of a pigmented scale/crust. All sites returned to normal skin color and texture without scarring within 3 to 6 months. These observations suggest that the human skin response to selective photothermolysis of pigmented cells is similar to that reported in animal models, including low radiant exposure stimulation of melanogenesis and high radiant exposure lethal injury to pigmented epidermal cells.

  1. Melanosomes are a primary target of Q-switched ruby laser irradiation in guinea pig skin

    Energy Technology Data Exchange (ETDEWEB)

    Polla, L.L.; Margolis, R.J.; Dover, J.S.; Whitaker, D.; Murphy, G.F.; Jacques, S.L.; Anderson, R.R.


    The specific targeting of melanosomes may allow for laser therapy of pigmented cutaneous lesions. The mechanism of selective destruction of pigmented cells by various lasers, however, has not been fully clarified. Black, brown, and albino guinea pigs were exposed to optical pulses at various radiant exposure doses from a Q-switched, 40 nsec, 694 nm ruby laser. Biopsies were analyzed by light and electron microscopy (EM). Albino animals failed to develop clinical or microscopic evidence of cutaneous injury after irradiation. In both black and brown animals, the clinical threshold for gross change was 0.4 J/cm2, which produced an ash-white spot. By light microscopy, alterations appeared at 0.3 J/cm2 and included separation at the dermoepidermal junction, and the formation of vacuolated epidermal cells with a peripheral cytoplasmic condensation of pigment. By EM, enlarged melanosomes with a central lucent zone were observed within affected epidermal cells at 0.3 J/cm2. At 0.8 and 1.2 J/cm2, individual melanosomes were more intensely damaged and disruption of melanosomes deep in the hair papillae was observed. Dermal-epidermal blisters were formed precisely at the lamina lucida, leaving basal cell membranes and hemidesmosomes intact. Possible mechanisms for melanosomal injury are discussed. These observations show that the effects of the Q-switched ruby laser are melanin-specific and melanin-dependent, and may be useful in the selective destruction of pigmented as well as superficial cutaneous lesions.

  2. Q-switched all-fiber laser with short pulse duration based on tungsten diselenide (United States)

    Li, Wenyi; OuYang, Yuyi; Ma, Guoli; Liu, Mengli; Liu, Wenjun


    Fiber lasers are widely used in industrial processing, sensing, medical and communications applications due to their simple structure, good stability and low cost. With the rapid development of fiber lasers and the sustained improvement of industrial laser quality requirements, researchers in ultrafast optics focus on how to get laser pulses with high output power and narrow pulse duration. Q-switched technology is one of the most effective techniques to generate ultrashort pulses. In this paper, a tungsten diselenide saturable absorber with 16.82% modulation depth is prepared by chemical vapor deposition. Experimental results show that when the pump power changes from 115.7 mW to 630 mW, the all-fiber laser can achieve a stable Q-switched pulse output. The repetition rate of the output pulse varies from 80.32 kHz to 204.2 kHz, the pulse duration is 581 ns, the maximum output power is 17.1 mW and the maximum pulse energy is 83.7 nJ. Results in this paper show that tungsten diselenide can be applied to ultrafast optics, which is a kind of saturable absorption material with excellent properties.

  3. A high-peak-power passively Q-switched composite variable-cut vanadate laser

    International Nuclear Information System (INIS)

    Sirotkin, A A


    We present laser sources based on a novel method of controlling spectral parameters in diode-pumped vanadate lasers. Angular dependences of the luminescence intensity of Stark transitions at the 4F3/2‒4I11/2 transition in vanadate crystals are investigated. The operation of diode-pumped passively Q-switched composite variable-cut (θ = var, φ = 0) YVO 4 –Nd 3+  : YVO 4 lasers with Cr 4+  : YAG saturable absorber is demonstrated (the narrowest pulse of 2 ns with the highest peak power of 24.3 kW). In the experiment, an efficient self-Raman laser was realized, based on the multifunctional variable-cut (θ = 25°, φ = 0) YVO 4 –Nd 3+  : YVO 4 laser crystal with the passive Q-switched. (letters)

  4. An Nd:YLF laser Q-switched by a monolayer-graphene saturable-absorber mirror

    International Nuclear Information System (INIS)

    Matía-Hernando, Paloma; Guerra, José Manuel; Weigand, Rosa


    We demonstrate Q-switched operation of a transversely diode-pumped Nd:YLF (yttrium lithium fluoride) laser using chemical vapour deposition-grown large-area monolayer graphene transferred to a dielectric saturable-absorber mirror (G-SAM). The resulting compact design operates at 1047 nm with 2.5 μs pulses in a 100% modulation Q-switch regime with an average and very stable output power of 0.5 W. Different cavity lengths have been employed and the results are compared against a theoretical model based on rate equations, evidencing the role of transverse pumping in the system. The model also reveals that monolayer graphene effectively leads to shorter and more powerful pulses compared to those with multilayer graphene. These results establish the potential of single-layer graphene for providing a reliable and efficient Q-switch mechanism in solid-state lasers. (paper)

  5. High power diode-pumped continuous wave and Q-switch operation of Tm,Ho:YVO4 laser

    International Nuclear Information System (INIS)

    Yao, B Q; Li, G; Meng, P B; Zhu, G L; Ju, Y L; Wang, Y Z


    High power diode-pumped continuous wave (CW) and Q-switch operation of Tm,Ho:YVO 4 laser is reported. Using two Tm,Ho:YVO 4 rods in a single cavity, up to 20.2 W of CW output lasing at 2054.7 nm was obtained under cryogenic temperature of 77 K with an optical to optical conversion efficiency of 32.9%. For Q-switch operation, up to 19.4 W of output was obtained under 15 kHz pulse repetition frequency (PRF) with a minimum pulse width of 24.2 ns. In addition, different pulse repetition frequencies of Q-switch operation with 10.0 kHz, 12.5 kHz and 15.0 kHz were investigated comparatively

  6. Structure of picosecond pulses of a Q-switched and mode-locked diode-pumped Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Donin, V I; Yakovin, D V; Gribanov, A V [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)


    The pulse duration of a diode-pumped Nd:YAG laser, in which Q-switching with mode-locking (QML regime) is achieved using a spherical mirror and a travelling-wave acousto-optic modulator, is directly measured with a streak camera. It is found that the picosecond pulses can have a non-single-pulse structure, which is explained by excitation of several competing transverse modes in the Q-switching regime with a pulse repetition rate of 1 kHz. In the case of cw mode-locking (without Q-switching), a new (auto-QML) regime is observed, in which the pulse train repetition rate is determined by the frequency of the relaxation oscillations of the laser field while the train contains single picosecond pulses. (control of laser radiation parameters)

  7. High-power continuous wave and passively Q-switched laser operations of a Nd:GGG crystal

    International Nuclear Information System (INIS)

    Qin, L J; Tang, D Y; Xie, G Q; Dong, C M; Jia, Z T; Tao, X T


    We report on the continuous wave (CW) and passive Q-switching performance of a high-power diode-pumped Nd:GGG laser. A CW output power of 7.20 W was obtained under an absorbed pump power of 14.97 W, which gives a slop efficiency of 52.7%. With a Cr 4+ doped yttrium aluminum garnet crystal as the saturable absorber, the shortest passively Q-switched pulse width, largest pulse energy, and highest peak power achieved were 7.7 ns, 126.25 μJ, and 15.5 kW, respectively

  8. Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm. (United States)

    Chang, N W H; Simakov, N; Hosken, D J; Munch, J; Ottaway, D J; Veitch, P J


    We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.

  9. Q-switching and mode-locking in a diode-pumped frequency-doubled Nd : YAG laser

    International Nuclear Information System (INIS)

    Donin, Valerii I; Yakovin, Dmitrii V; Gribanov, A V


    A new method for obtaining Q-switching simultaneously with mode-locking using one travelling-wave acousto-optic modulator in a frequency-doubled Nd : YAG laser cavity is described. Further shortening of output laser pulses (from 40 to 3.25 ps) is achieved by forming a Kerr lens in the frequency-doubling crystal. At an average power of ∼ 2 W and a Q-switching rate of 2 kHz, the peak power of the stably operating reached ∼ 50 MW.

  10. Nanosecond Tm:Y2O3 ceramic laser passively Q-switched by a Ho:LuAG ceramic (United States)

    Wang, Hui; Huang, Haitao; Wang, Shiqiang; Shen, Deyuan


    A passively Q-switched 2.05-μm Tm:Y2O3 ceramic laser, employing Ho:LuAG ceramic as a saturable absorber, was demonstrated for the first time. Under the absorbed pump power of 20.5 W, a maximum output power of 497 mW was obtained. Pulses with a minimum pulse width of 642 ns under the repetition rate of 33 kHz were achieved. Our works validate that Ho-doped materials have good potential for passive Q-switching of Tm-doped lasers at 2-μm wavelength region.

  11. Pulsed Q-switched ruby laser annealing of Bi implanted Si crystals investigated by channeling

    International Nuclear Information System (INIS)

    Deutch, B.I.; Shih-Chang, T.; Shang-Hwai, L.; Zu-Yao, Z.; Jia-Zeng, H.; Ren-Zhi, D.; Te-Chang, C.; De-Xin, C.


    Channeling was used to investigate pulsed, Q switched ruby-laser annealed and thermally annealed Si single crystals implanted with 40-keV Bi ions to a dose of 10 15 atoms/cm 2 . After thermal annealing, residual damage decreased with increasing annealing temperature to a minimum value of 30% at 900 0 C. The Bi atoms in substitutional sites reached a maximum value (50%) after annealing at 750 0 C but decreased with increasing annealing temperature. Out diffusion of Bi atoms occurred at temperatures higher than 625 0 C. For comparison, the residual damage disappeared almost completely after pulsed-laser annealing (30 ns pulse width, Energy, E = 3J/cm 2 ). The concentration of Bi in Si exceeded its solid solubility by an order of magnitude; 95% of Bi atoms were annealed to substitutional sites. Laser pulses of different energies were used to investigate the efficiency of annealing. (author)

  12. Intraoperative localized urticarial reaction during Q-switched Nd:YAG laser tattoo removal. (United States)

    Wilken, Reason; Ho, Derek; Petukhova, Tatyana; Jagdeo, Jared


    Q-switched lasers, such as the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, are the gold standard for tattoo removal. Allergy to tattoo pigment is well-documented, but adverse allergic reactions during or shortly after laser tattoo removal are rare with few reports in the medical literature. Here we describe an intraoperative, localized urticarial reaction that developed during treatment of a tattoo using a 1064-nm Nd:YAG laser. As laser tattoo removal becomes increasingly popular amongst our patients, it is important for dermatologists to be aware of urticarial allergic reactions as well as their management. We outline our recommendations for medical management of this condition and hope that these guidelines will facilitate patient care by dermatologists who encounter this immune skin reaction to laser tattoo removal

  13. Precise alignment of a longitudinal Pockels Cell for Q-switch operation Nd:YAG laser

    International Nuclear Information System (INIS)

    Nisperuza, D.; Botero, G.; Bastidas, A.


    The failure to accurately center optical components may, especially in the case of high gain of the Nd:YAG lasers, produce strong parasitic off-axis laser action capable of causing severe component damage typically to the Pockels cell. We report a precise longitudinal alignment of the Pockels cell by modulating the laser polarization using an experimental setup of circular dichroism. This procedure is based on the use of an analyzer at 0 o or 45 o of the Pockels cell axes, and it allows us to adjust the Q-switching delay for best pulse shape, maximum output energy and to reduce the lack of symmetry of the spot laser considerably. (Author)

  14. Diode pumped actively Q-switched Nd:YVO4 self-Raman laser

    International Nuclear Information System (INIS)

    Su Fufang; Zhang Xingyu; Wang Qingpu; Ding Shuanghong; Jia Peng; Li Shutao; Fan Shuzhen; Zhang Chen; Liu Bo


    By using Nd:YVO 4 as the gain medium and the Raman medium simultaneously, the actively Q-switched operation of the self-Raman Nd:YVO 4 laser at 1176 nm was realized. The output characteristics including the average power, pulse energy and pulse width versus the incident pump power and pulse repetition rate were investigated. At a pulse repetition rate of 20 kHz an average power up to 0.57 W was obtained with the incident pump power of 10.2 W, corresponding to a conversion efficiency of 5.6% with respect to the diode laser input power. Meanwhile, an analysis of the self-Raman Nd:YVO 4 laser was carried out by using the rate equations. The obtained theoretical results were in agreement with the experimental results on the whole

  15. Q-Switched Operation with Carbon-Based Saturable Absorbers in a Nd:YLF Laser

    Directory of Open Access Journals (Sweden)

    Rosa Weigand


    Full Text Available We have numerically studied the influence of the absorption modulation depth of carbon-based saturable absorbers (graphene and carbon nanotubes (CNTs on the Q-switched regime of a diode-pumped Nd:YLF laser. A short-length cavity was used with an end mirror on which CNTs or mono- or bi-layer graphene were deposited, forming a saturable absorber mirror (SAM. Using a standard model, the generated energy per pulse was calculated, as well as the pulse duration and repetition rate. The results show that absorbers with higher modulation depths, i.e., graphene, deliver higher energy pulses at lower repetition rates. However, the pulse duration did not have a monotonic behavior and reaches a minimum for a given low value of the modulation depth typical of CNTs.

  16. Q-switched laser removal of tattoos: a clinical and spectroscopic investigation of the mechanism (United States)

    Siomos, Konstadinos; Bailey, Raymond T.; Cruickshank, Frank R.; Murphy, Michael


    The liquid phase spectra of tatoo pigments are shown to be unreliable as a basis for mechanistic deductions. The reflectance spectra of the solids from 2000 nm to 500 nm (5000 to 20,000 cm-1) are shown to accurately assess the relative loss of laser light for different pigments and to be useful in examining these to check for similarities in the pigments. The absorbance differences between the pigments are shown to be largely irrelevant in assessing the ease of tatoo removal by laser radiation of a variety of wavelengths. A multiphoton absorption mechanism with its concomitant shock wave is proposed to be responsible for the reduction of pigment particles to small sizes which the lymph system can remove. The different behavior of blue and green tattoos, treated by Q-switched ruby and Nd:YAG lasers, is attributed to the particle aggregation size of the pigments in the tattoo.

  17. Actively Q-switched laser with novel Nd:YAG/YAG polygonal active-mirror (United States)

    Lang, Ye; Chen, Yanzhong; Ge, Wenqi; He, Jianguo; Zhang, Hongbo; Liao, Lifen; Xin, Jianguo; Zhang, Jian; Fan, Zhongwei


    In this work, we demonstrate an efficient actively Q-switched laser based on a novel crystal Nd:YAG/YAG polygonal active mirror. A passively cooled crystal Nd:YAG/YAG polygonal active mirror with an end pump scheme was used as the gain medium. For the overlap between the TEM00 laser mode and large gain profile, a cavity was carefully designed with a large fundamental mode volume. With a maximum absorbed power of 3.1 W, a 685 mW average output power with a pulse repetition of 5 kHz was attained, and the corresponding optical-optical and slope efficiency were 22.1% and 27.7%, respectively. The pulse width was 133.9 ns. The beam quality (M 2) was 1.561 in the horizontal direction and 1.261 in the vertical direction.

  18. High Power Q-Switched Dual-End-Pumped Ho:YAG Laser

    Energy Technology Data Exchange (ETDEWEB)

    Xiao-Ming, Duan; Ying-Jie, Shen; Tong-Yu, Dai; Bao-Quan, Yao; Wang Yue-Zhu, E-mail: [National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001 (China)


    We report the high power acousto-optically Q-switched operation of a dual-end-pumped Ho:YAG laser at room temperature. For the Q-swithched mode, a maximum pulse energy of 2.4 mJ and a minimum pulse width of 23 ns at the repetition rate of 10 kHz are achieved, resulting in a peak power of 104.3 kW. The beam quality factor of M{sup 2} {approx} 1.5, which is demonstrated by a knife-edge method. In addition, the Ho:YAG laser is employed as a pumping source of ZGP optical parametric oscillator, and its total average output power is 13.2 W at 3.9 {mu}m and 4.4 {mu}m with a slope efficiency of 68.4%.

  19. Effect of Q-switched Laser Surface Texturing of Titanium on Osteoblast Cell Response (United States)

    Voisey, K. T.; Scotchford, C. A.; Martin, L.; Gill, H. S.

    Titanium and its alloys are important biomedical materials. It is known that the surface texture of implanted medical devices affects cell response. Control of cell response has the potential to enhance fixation of implants into bone and, in other applications, to prevent undesired cell adhesion. The potential use of a 100W Q-switched YAG laser miller (DMG Lasertec 60 HSC) for texturing titanium is investigated. A series of regular features with dimensions of the order of tens of micrometers are generated in the surface of titanium samples and the cell response to these features is determined. Characterisation of the laser milled features reveals features with a lengthscale of a few microns superposed on the larger scale structures, this is attributed to resolidification of molten droplets generated and propelled over the surface by individual laser pulses. The laser textured samples are exposed to osteoblast cells and it is seen that cells do respond to the features in the laser textured surfaces.

  20. Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury. (United States)

    Krebs, Danny J; Novo-Gradac, Anne-Marie; Li, Steven X; Lindauer, Steven J; Afzal, Robert S; Yu, Anthony W


    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

  1. Tattoo removal by Q-switched yttrium aluminium garnet laser: client satisfaction. (United States)

    Hutton Carlsen, K; Esmann, J; Serup, J


    Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. To determine clients' satisfaction with tattoo removal. One hundred and fifty-four tattoo removal clients who had attended the private clinic 'Centre for Laser Surgery', Hellerup, Denmark, from 2001 to 2013 completed a questionnaire concerning outcome expectations, level of pain experiences and satisfaction with tattoo removal. The laser surgeon and his team were blinded from data handling. The study design included a minimum 2-year postlaser treatment observation period from 2013 to 2015. Overall, clients were satisfied with their laser treatment; 85% assessed their treatment and results to be acceptable to superb, while 15% assessed their treatment and results to be inferior to unacceptable. Effectiveness relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate to extreme pain during treatment. Twenty-eight (20%) developed minor scarring. There were many reasons for tattoo removal; e.g. stigmatisation (33%), conspicuousness (29%) and poor artistic quality (22%). One hundred and two clients had expected complete removal of tattoos without a blemish, expectations that were only partly fulfilled. During the treatment period, clients adjusted expectations and adapted more realistic views of outcomes. The majority of clients were satisfied with Q-switched YAG laser removal of tattoos despite high pretreatment expectations which were only partly met. The study supports YAG lasers for tattoo removal as acceptable therapy of today, with room for new approaches. © 2017 European Academy of Dermatology and Venereology.

  2. Fully integrated Q-switch for commercial high-power resonator with solitary XLMA-fiber (United States)

    Lange, R.; Bachert, C.; Rehmann, G.; Weber, H.; Luxen, R.; Enns, H.; Schenk, M.; Hosdorf, S.; Marfels, S.; Bay, M.; Kösters, A.; Krause, V.; Giesberts, M.; Fitzau, O.; Hoffmann, H.-D.


    In surface processing applications the correlation of laser power to processing speed demands a further enhancement of the performance of short-pulsed laser sources with respect to the investment costs. The frequently applied concept of master oscillator power amplifier relies on a complex structure, parts of which are highly sensitive to back reflected amplified radiation. Aiming for a simpler, robust source using only a single ytterbium doped XLMA fiber in a q-switched resonator appears as promising design approach eliminating the need for subsequent amplification. This concept requires a high power-tolerant resonator which is provided by the multikilowatt laser platform of Laserline including directly water-cooled active fiber thermal management. Laserline GmbH and Fraunhofer Institute for Laser Technology joined their forces1 to upgrade standard high power laser sources for short-pulsed operation exceeding 1 kW of average power. Therefor a compact, modular qswitch has been developed. In this paper the implementation of a polarization independent q-switch into an off-the-shelf multi-kilowatt diodepumped continuous wave fiber source is shown. In this early step of implementation we demonstrated more than 1000 W of average power at pulse lengths below 50 ns FWHM and 7.5 mJ pulse energy. The M2 corresponds to 9.5. Reliability of the system is demonstrated based on measurements including temperature and stability records. We investigated the variation possibilities concerning pulse parameters and shape as well as upcoming challenges in power up-scaling.

  3. Dynamics of a self-Q-switched fiber laser with a Rayleigh-stimulated Brillouin scattering ring mirror (United States)

    Fotiadi, Andrei A.; Mégret, Patrice; Blondel, Michel


    Backward light scattering can cause passive Q switching in fiber lasers. We propose a self-consistent description of the laser dynamics. Our model quantitatively reproduces the temporal structure of pulsation and is also attractive for analysis of laser stability and statistics. The validity of the model is directly verified in an experiment.

  4. Passive Q-switching in CW-CO2 laser with SF6 as an intracavity saturable absorber

    International Nuclear Information System (INIS)

    Al-Hawat, Sh.


    A passive Q-switching was applied to a tunable CW CO 2 laser with output power about 3.5 W using SF 6 as a saturable absorber inside the cavity. The Q-Switching phenomenon was studied ( pulse shape, pulse duration, repetition rate and conditions of its generation ) at the spectral lines of 10P(10), 10P(26), 10P(28) and 10P(30) from the branch of 10P of CO 2 laser. These lines had a weak absorption in relation to other lines of this branch, under SF 6 pressure till 0.5 mbar. To control the behaviour of such phenomenon, the gases He and Xe were added separately to SF 6 . It was observed that the Q-switching phenomenon was depended on the added gas pressure of Xe and He, through the repetitive rate of pulses , duration and energy of generated laser pulse. A computational program was written to calculate the Q-switching pulses parameters under similar conditions as those applied in the case of SF 6 +He mixture. A comparison was made with the experimental data , not so big discrepancies were observed between them. In addition to that, absorption coefficients of SF 6 were determined in two cases: the first one when the absorption cell was located outside the laser cavity, and the second one when the cell was located inside the cavity. On the basis of obtained coefficients the absorption cross sections of SF 6 were found and compared with NIST database.(author)

  5. Yb:KYW planar waveguide laser Q-switched by evanescent-field interaction with carbon nanotubes

    NARCIS (Netherlands)

    Kim, Jun Wan; Choi, Sun Young; Yeom, Dong-Il; Aravazhi, S.; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Rotermund, Fabian


    We report Q-switched operation of a planar waveguide laser by evanescent-field interaction with single-walled carbon nanotubes deposited on top of the waveguide. The saturable-absorber-integrated gain medium, which operates based on evanescent-field interaction, enables the realization of a

  6. Treatment of pigmented keratosis pilaris in Asian patients with a novel Q-switched Nd:YAG laser. (United States)

    Kim, Sangeun


    Treatment for most cases of keratosis pilaris requires simple reassurance and general skin care recommendations. Many Asian patients find lesions due to pigmented keratosis pilaris to be cosmetically unappealing. Treatment of post-inflammatory hyperpigmentation using a 1064-nm Q-switched Nd:YAG laser with low fluence is reported. To investigate the efficacy of a novel Q-switched Nd:YAG laser for the treatment of pigmented keratosis pilaris in Asian patients. Ten patients with pigmented keratosis pilaris underwent five weekly treatments using a Q-switched Nd:YAG laser (RevLite(®); HOYA ConBio(®), Freemont, CA, USA) at 1064 nm with a 6-mm spot size and a fluence of 5.9 J/cm(2). Photographic documentation was obtained at baseline and 2 months after the final treatment. Clinical improvement was achieved in all 10 patients with minimal adverse effects. For the treatment of keratosis pilaris, the use of a Q-switched Nd:YAG laser can be helpful for improving cosmetic appearance as it can improve pigmentation.

  7. Q-Switched Nd:YAG Laser Removal of Facial Amateur Tattoos in Patients With Fitzpatrick Type VI: Case Series. (United States)

    Haik, Josef; Kornhaber, Rachel; Harats, Moti; Israeli, Hadar; Orenstein, Arie


    Q-switched neodymium:YAG (Nd:YAG) lasers are reported to be gold standard for laser tattoo removal. In particular, the Q-switched Nd:YAG laser at 1064 nm is widely recognized for the removal of blue/black amateur tattoos. However, treatment modalities in Fitzpatrick Type VI skin carry a greater risk of complications including alterations in pigmentation compared to fairer skin (Fitzpatrick Type I-IV skin). Therefore, the aim of this case series was to describe with the use of the Q-Switched Nd:YAG laser, the removal of carbon-based amateur tattoos on patients with Fitzpatrick Type VI skin as an effective and safe method. Twenty- five patients with Fitzpatrick type VI skin, from Ethiopian origins, with facial tribal tattoos, were treated with the Q- Switched Nd:YAG laser at 1064 nm. Digital images were taken upon every treatment and the clearance rates of the tattoo was evalu- ated by imaging software. We observed an average tattoo clearance rate of 95% among the 45 facial tattoos in 25 patients presented in the case series with minimal pigmentary and textual changes evident. These positive aesthetic results have a signi cant psychosocial impact on the lives of those with Fitzpatrick Type VI skin, in particular the Ethiopian Jewish population. J Drugs Dermatol. 2016;15(11):1448-1452..

  8. Generation of Q-Switched Mode-Locked Erbium-Doped Fiber Laser Operating in Dark Regime

    International Nuclear Information System (INIS)

    Tiu, Zian Cheak; Zarei, Arman; Ahmad, Harith; Harun, Sulaiman Wadi


    We demonstrate a stable Q-switched mode-locked erbium-doped fiber laser (EDFL) operating in dark regime based on the nonlinear polarization rotation technique. The EDFL produces a pulse train where the Q-switching envelope is formed by multiple dark pulses. The repetition rate of the Q-switched envelope can be increased from 0.96 kHz to 3.26 kHz, whereas the pulse width reduces from 211 μs to 86 μs. The highest pulse of 479 nJ is obtained at the pump power of 55 mW. It is also observed that the dark pulses inside the Q-switching envelope consist of two parts: square and trailing dark pulses. The shortest pulse width of the dark square pulse is obtained at 40.5 μs when the pump power is fixed at 145 mW. The repetition rate of trailing dark pulses can be increased from 27.62 kHz to 50 kHz as the pump power increases from 55 mW to 145 mW. (paper)

  9. High resolution laser micro sintering / melting using q-switched and high brilliant laser radiation (United States)

    Exner, H.; Streek, A.


    Since the discovery of selective laser sintering/melting, numerous modifications have been made to upgrade or customize this technology for industrial purposes. Laser micro sintering (LMS) is one of those modifications: Powders with particles in the range of a few micrometers are used to obtain products with highly resolved structures. Pulses of a q-switched laser had been considered necessary in order to generate sinter layers from the micrometer scaled metal powders. LMS has been applied with powders from metals as well as from ceramic and cermet feedstock's to generate micro parts. Recent technological progress and the application of high brilliant continuous laser radiation have now allowed an efficient laser sintering/melting of micrometer scaled metal powders. Thereby it is remarkable that thin sinter layers are generated using high continuous laser power. The principles of the process, the state of the art in LMS concerning its advantages and limitations and furthermore the latest results of the recent development of this technology will be presented. Laser Micro Sintering / Laser Micro Melting (LMM) offer a vision for a new dimension of additive fabrication of miniature and precise parts also with application potential in all engineering fields.

  10. Simulation of medical Q-switch flash-pumped Er:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanlin; Huang Chuyun; Yao Yucheng; Zou Xiaolin, E-mail:, E-mail:, E-mail:, E-mail: [Physics school, Hubei University of Technology, Wuhan, China 430068 (China)


    Er: YAG laser, the wavelength is 2940nm, can be absorbed strongly by water. The absorption coefficient is as high as 13000 cm{sup -1}. As the water strong absorption, Erbium laser can bring shallow penetration depth and smaller surrounding tissue injury in most soft tissue and hard tissue. At the same time, the interaction between 2940nm radiation and biological tissue saturated with water is equivalent to instantaneous heating within limited volume, thus resulting in the phenomenon of micro-explosion to removal organization. Different parameters can be set up to cut enamel, dentin, caries and soft tissue. For the development and optimization of laser system, it is a practical choice to use laser modeling to predict the influence of various parameters for laser performance. Aim at the status of low Erbium laser output power, flash-pumped Er: YAG laser performance was simulated to obtain optical output in theory. the rate equation model was obtained and used to predict the change of population densities in various manifolds and use the technology of Q-switch the simulate laser output for different design parameters and results showed that Er: YAG laser output energy can achieve the maximum average output power of 9.8W under the given parameters. The model can be used to find the potential laser systems that meet application requirements.

  11. 183-W, M2 = 2.4 Yb:YAG Q -switched laser

    International Nuclear Information System (INIS)

    Honea, E.C.; Beach, R.J.; Mitchell, S.C.; Avizonis, P.V.


    We have fabricated a diode-array end-pumped Yb:YAG rod laser with output powers greater than 200thinspthinspW cw and 195thinspthinspW Q -switched at 5thinspthinspkHz. At an output power of 183thinspthinspW and a repetition rate of 5thinspthinspkHz, the beam quality was measured to be M 2 =2.4 . The laser design incorporates a hollow lens duct to concentrate the diode pump light for delivery to the end of the laser rod while maintaining access to the laser beam. This configuration provides increased flexibility for the resonator design and permits the use of birefringence compensation in the cavity to yield polarized output with increased efficiency. Using the recently described birefringence compensation method of Clarkson et al.thinspthinsp[in Conference on Lasers and Electro-Optics (Optical Society of America, Washington, D.C., 1998), paper CTuI3], we obtained 112thinspthinspW of cw power with a polarized beam of M 2 =3.2 . copyright 1999 Optical Society of America

  12. Water content contribution in calculus phantom ablation during Q-switched Tm:YAG laser lithotripsy. (United States)

    Zhang, Jian J; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Wang, Hui; Chia, Ray W J; Hasenberg, Tom; Kang, Hyun Wook


    Q-switched (QS) Tm:YAG laser ablation mechanisms on urinary calculi are still unclear to researchers. Here, dependence of water content in calculus phantom on calculus ablation performance was investigated. White gypsum cement was used as a calculus phantom model. The calculus phantoms were ablated by a total 3-J laser pulse exposure (20 mJ, 100 Hz, 1.5 s) and contact mode with N=15 sample size. Ablation volume was obtained on average 0.079, 0.122, and 0.391  mm3 in dry calculus in air, wet calculus in air, and wet calculus in-water groups, respectively. There were three proposed ablation mechanisms that could explain the effect of water content in calculus phantom on calculus ablation performance, including shock wave due to laser pulse injection and bubble collapse, spallation, and microexplosion. Increased absorption coefficient of wet calculus can cause stronger spallation process compared with that caused by dry calculus; as a result, higher calculus ablation was observed in both wet calculus in air and wet calculus in water. The test result also indicates that the shock waves generated by short laser pulse under the in-water condition have great impact on the ablation volume by Tm:YAG QS laser.

  13. Continuous-wave and passively Q-switched Nd:YVO4 laser at 1085 nm (United States)

    Lin, Hongyi; Liu, Hong; Huang, Xiaohua; Zhang, Jiyan


    An admirable and efficient Nd:YVO4 laser at 1085 nm is demonstrated with a compact 35 mm plano-plano cavity. A chosen narrow bandpass filter with high-transmittance (HT) coating at 1064 nm (T=96%) and optimized part-reflection (PR) coating at 1085 nm (T=15%) is used as the output coupler. In the continuous-wave (CW) regime, the maximum output power reaches 3110 mW at the pump power of 11.41 W. Based on a Cr:YAG crystal with initial-transmittance of 91%, the first passively Q-switched Nd:YVO4 laser at 1085 nm is achieved. When the pump power is changed from the threshold of 4.50 to 6.08 W, the dual-wavelength lines at 1064 and 1085 nm are generated simultaneously. However, at the pump power of above 6.08 W, the single-wavelength line at 1085 nm is achieved. The largest output power, the highest peak power, and the narrowest pulse width are 1615 mW, 878 W and 26.2 ns, respectively.

  14. SBS pulse compression applied to a commercial Q-switch Nd-YAG laser

    International Nuclear Information System (INIS)

    Aliaga-Rossel, R.; Bayley, J.; Mamin, A.; Nizienko, Y.


    In optical diagnosis of dense Z-pinches, sub-nanosecond laser pulses are required in order to freeze the movement of the plasma during the probing. Commercial lasers can provide such type of pulses but they are either very expensive, or they have a very low energy per pulse. A technique that uses Stimulated Brillouin Scattering (SBS) to compress a 8 ns pulse of a commercial Q-switched Nd-YAG laser is reported here. To carry out this passive compression technique, a frequency doubled laser pulse of 10 ns was focused into a single SBS gas cell, 2 m long, filled with a mixture of argon and sulphurhexafluoride (SF 6 ) at a total pressure of 40 bar. A shorter and high intensity pulse was reflected from the cell (created by SBS) and it travelled back along its original path until it was separated from its original direction by using a dichroic polariser. The pumping volume of the SBS cell, the convergence of the incident beam and the pressure of the gas cell, were optimised to maximise both temporal compression and the output energy. Pulses of 10 ns were compressed to less than 400 ps with a conversion efficiency of 80%. This SBS pulse compression system has been used to make most of the optical measurements of a dense fibre pinch plasma produced in the MAGPIE generator

  15. Light and electron microscopic analysis of tattoos treated by Q-switched ruby laser

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, C.R.; Anderson, R.R.; Gange, R.W.; Michaud, N.A.; Flotte, T.J. (Massachusetts General Hospital, Boston (USA))


    Short-pulse laser exposures can be used to alter pigmented structures in tissue by selective photothermolysis. Potential mechanisms of human tattoo pigment lightening with Q-switched ruby laser were explored by light and electron microscopy. Significant variation existed between and within tattoos. Electron microscopy of untreated tattoos revealed membrane-bound pigment granules, predominantly within fibroblasts and macrophages, and occasionally in mast cells. These granules contained pigment particles ranging from 2-in diameter. Immediately after exposure, dose-related injury was observed in cells containing pigment. Some pigment particles were smaller and lamellated. At fluences greater than or equal to 3 J/cm2, dermal vacuoles and homogenization of collagen bundles immediately adjacent to extracellular pigment were occasionally observed. A brisk neutrophilic infiltrate was apparent by 24 h. Eleven days later, the pigment was again intracellular. Half of the biopsies at 150 d revealed a mild persistent lymphocytic infiltrate. There was no fibrosis except for one case of clinical scarring. These findings confirm that short-pulse radiation can be used to selectively disrupt cells containing tattoo pigments. The physial alteration of pigment granules, redistribution, and elimination appear to account for clinical lightening of the tattoos.

  16. Multi-operational tuneable Q-switched mode-locking Er fibre laser (United States)

    Qamar, F. Z.


    A wavelength-spacing tuneable, Q-switched mode-locking (QML) erbium-doped fibre laser based on non-linear polarization rotation controlled by four waveplates and a cube polarizer is proposed. A mode-locked pulse train using two quarter-wave plates and a half-wave plate (HWP) is obtained first, and then an extra HWP is inserted into the cavity to produce different operation regimes. The evolutions of temporal and spectral dynamics with different orientation angles of the extra HWP are investigated. A fully modulated stable QML pulse train is observed experimentally. This is, to the author’s best knowledge, the first experimental work reporting QML operation without adding an extra saturable absorber inside the laser cavity. Multi-wavelength pulse laser operation, multi-pulse train continuous-wave mode-locking operation and pulse-splitting operations are also reported at certain HWP angles. The observed operational dynamics are interpreted as a mutual interaction of dispersion, non-linear effect and insertion loss. This work provides a new mechanism for fabricating cheap tuneable multi-wavelength lasers with QML pulses.

  17. High-damage-resistant tungsten disulfide saturable absorber mirror for passively Q-switched fiber laser. (United States)

    Chen, Hao; Chen, YuShan; Yin, Jinde; Zhang, Xuejun; Guo, Tuan; Yan, Peiguang


    In this paper, we demonstrate a high-damage-resistant tungsten disulfide saturable absorber mirror (WS2-SAM) fabricated by magnetron sputtering technique. The WS2-SAM has an all-fiber-integrated configuration and high-damage-resistant merit because the WS2 layer is protected by gold film so as to avoid being oxidized and destroyed at high pump power. Employing the WS2-SAM in an Erbium-doped fiber laser (EDFL) with linear cavity, the stable Q-switching operation is achieved at central wavelength of 1560 nm, with the repetition rates ranging from 29.5 kHz to 367.8 kHz and the pulse duration ranging from 1.269 μs to 154.9 ns. For the condition of the maximum pump power of 600 mW, the WS2-SAM still works stably with an output power of 25.2 mW, pulse energy of 68.5 nJ, and signal-noise-ratio of 42 dB. The proposed WS2-SAM configuration provides a promising solution for advanced pulsed fiber lasers with the characteristics of high damage resistance, high output energy, and wide tunable frequency.

  18. Double-Arched LD Array Stagger Pumped Electro-Optic Q-Switched Nd:YAG Laser without Water Cooling

    International Nuclear Information System (INIS)

    Xin-Yu, Chen; Guang-Yong, Jin; Yong-Ji, Yu; Chao, Wang; Da-Wei, Hao; Yi-Bo, Wang


    We report an experimental study on a double-arched LD array stagger pumped electro-optic Q-switched Nd:YAG laser without water cooling by using a convex-concave compensate resonator. Perfect matching of the gain field inside the rod and the fundamental mode of the cavity is made by this structure. When the repetition rate is 20 Hz, A maximum output energy at 1064 nm wavelength of 176 mJ (M 2 = 1.55) and 9.6 ns FWHM pulse width in fundamental mode Q-switch operation is obtained with LD injection current 120 A. The optical-optical conversion efficiency is 14.7%, the divergence angle of the output beam is about 1.8 mrad. (fundamental areas of phenomenology(including applications))

  19. Passively Q-switched microchip Er, Yb:YAl3(BO3)4 diode-pumped laser. (United States)

    Kisel, V E; Gorbachenya, K N; Yasukevich, A S; Ivashko, A M; Kuleshov, N V; Maltsev, V V; Leonyuk, N I


    We report, for the first time to our knowledge, a diode-pumped cw and passively Q-switched microchip Er, Yb:YAl(3)(BO(3))(4) laser. A maximal output power of 800 mW at 1602 nm in the cw regime was obtained at an absorbed pump power of 7.7 W. By using Co(2+):MgAl(2)O(4) as a saturable absorber, a TEM(00)-mode Q-switched average output power of 315 mW was demonstrated at 1522 nm, with pulse duration of 5 ns and pulse energy of 5.25 μJ at a repetition rate of 60 kHz.

  20. Q-switched Yb3+:YAG laser using plasmonic Cu2-xSe quantum dots as saturable absorbers (United States)

    Wang, Yimeng; Zhan, Yi; Lee, Sooho; Wang, Li; Zhang, Xinping


    Cu2-xSe quantum dots (QDs) were synthesized by organometallic synthesis methods. Due to heavy self-doping, the Cu2-xSe QDs exhibit particle plasmon resonance in the near-infrared. Transient absorption spectroscopic investigation revealed strong nonlinear optical absorption and bleaching performance of the QDs under femtosecond pulse excitation, which enabled the Cu2-xSe QDs to be excellent saturable absorbers and applied in Q-switched or mode-locked lasers. A passively Q-switched Yb3+:YAG solid-state laser at 1.03 μm was achieved by coating Cu2-xSe QDs as saturable absorbers onto one of the output coupler of the V-shaped linear cavity.

  1. Acousto-Optic Q-Switched Fiber Laser-Based Intra-Cavity Photoacoustic Spectroscopy for Trace Gas Detection

    Directory of Open Access Journals (Sweden)

    Qinduan Zhang


    Full Text Available We proposed a new method for gas detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser by merging a transmission PAS cell (resonant frequency f0 = 5.3 kHz inside the fiber laser cavity. The Q-switching was achieved by an acousto-optic modulator, achieving a peak pulse power of ~679 mW in the case of the acousto-optic modulation signal with an optimized duty ratio of 10%. We used a custom-made fiber Bragg grating with a central wavelength of 1530.37 nm (the absorption peak of C2H2 to select the laser wavelength. The system achieved a linear response (R2 = 0.9941 in a concentration range from 400 to 7000 ppmv, and the minimum detection limit compared to that of a conventional intensity modulation system was enhanced by 94.2 times.

  2. Acousto-Optic Q-Switched Fiber Laser-Based Intra-Cavity Photoacoustic Spectroscopy for Trace Gas Detection. (United States)

    Zhang, Qinduan; Chang, Jun; Wang, Qiang; Wang, Zongliang; Wang, Fupeng; Qin, Zengguang


    We proposed a new method for gas detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser by merging a transmission PAS cell (resonant frequency f ₀ = 5.3 kHz) inside the fiber laser cavity. The Q-switching was achieved by an acousto-optic modulator, achieving a peak pulse power of ~679 mW in the case of the acousto-optic modulation signal with an optimized duty ratio of 10%. We used a custom-made fiber Bragg grating with a central wavelength of 1530.37 nm (the absorption peak of C₂H₂) to select the laser wavelength. The system achieved a linear response (R² = 0.9941) in a concentration range from 400 to 7000 ppmv, and the minimum detection limit compared to that of a conventional intensity modulation system was enhanced by 94.2 times.

  3. Laboratory model for the study and treatment of traumatic tattoos with the Q-switched ruby laser (United States)

    Silverman, Richard T.; Lach, Elliot


    The outcome of laser tattoo removal is dependent on the type of laser and characteristics of the tattoo. A rabbit model was developed to study the Q-switched ruby laser in the treatment of traumatic tattooing. On the backs of white New Zealand rabbits, three 3 cm patches were dermabraded and dressed with carbon black and antibiotic ointment. After a healing period of eight weeks, pre-treatment biopsies were obtained, and the rabbits were treated with the Q- switched ruby laser at various fluence settings with a pulse width of 34 nsec. At set intervals, further biopsies were obtained and studied with light and electron microscopic analysis, and photodocumentation was performed. Grossly, clearance of the tattooed areas was noted in the laser treated specimens. More effective clearance was observed with higher fluence treatment. No infections occurred, and hair regrowth was noted in all cases, though the rate seemed to be altered by laser treatment.

  4. A study on the clinical characteristics of treating nevus of Ota by Q-switched Nd:YAG laser. (United States)

    Yan, Liu; Di, Li; Weihua, Wang; Feng, Liu; Ruilian, Li; Jun, Zhou; Hui, Su; Zhaoxia, Ying; Weihui, Zeng


    The purpose of this study was to retrospectively analyze the clinical characteristics of treating nevus of Ota by Q-switched Nd:YAG laser in Laser Cosmetology Center of Department of Dermatology, the Second Hospital, Xi'an Jiaotong University. The data of 1168 patients of nevus of Ota were analyzed retrospectively, which included the correlation among lesion color, treatment sessions, sex, age, lesion types, and effect. The Q-switched (QS) Nd:YAG laser system had a higher number of treatment sessions which were positively associated with a better response to treatment. Other variables, including gender, age, the categorization of the lesion according to Tanino's classification, and the color of the lesion, were not associated with the response to treatment. The treatment of nevus of Ota with QS Nd:YAG laser is safe and effective, with rare complications.

  5. Comprehensive study of electro-optic and passive Q-switching in solid state lasers for altimeter applications (United States)

    Bhardwaj, Atul; Agrawal, Lalita; Pal, Suranjan; Kumar, Anil


    Laser Science and Technology Center (LASTEC), Delhi, is developing a space qualified diode pumped Nd: YAG laser transmitter capable of generating 10 ns pulses of 30 mJ energy @ 10 pps. This paper presents the results of experiments for comparative studies between electro-optic and passively Q-switched Nd: YAG laser in a crossed porro prism based laser resonator. Experimental studies have been performed by developing an economical bench model of flash lamp pumped Nd: YAG laser (rod dimension, \

  6. Use of Q-switched alexandrite laser (755 nm, 100 nsec) for removal of traumatic tattoo of different origins. (United States)

    Moreno-Arias, G A; Casals-Andreu, M; Camps-Fresneda, A


    Q-switched laser systems have been used for removal of tattoo-related carbon, graphite, and other particles. We assessed elimination of traumatic tattoos of different origin with Q-switched alexandrite laser in nine patients. Fluence threshold was determined and a spot test was made. Q-switched alexandrite laser, with a fluence range 4.5-8.0 J/cm(2) (mean, 7.16 +/- 1.18), was used at 4-5-week intervals. Total treatment ranged from 3-12 sessions (mean, 6.1 +/- 3.6 sessions). Double-pulse technique was used in black/black-bluish areas, but single-shot was applied to slate-gray pigment. More than 95% lightening was achieved in five patients after 5.2 +/- 2.3 sessions, and >75% lightening in six subjects after 6.1 +/- 3.1 sessions of treatment. Blacktop, surgical pen, and gravel tattoos presented a better response than gunpowder/fireworks tattoos (>95% vs. 68.7 +/- 23.9% clearance), or tattoos of unknown origin (>95% vs. 62.5 +/- 53% clearance). Epidermal splattering and pinpoint bleeding were observed in one case. No pigmentary alteration or scarring was seen. The Q-switched alexandrite laser is a useful system for removal of traumatic tattoos of diverse origin. The best response (>95% clearance) was achieved in blacktop, surgical pen, and gravel tattoos, although an acceptable degree of lightening may be obtained in tattoos due to gunpowder or fireworks. Copyright 1999 Wiley-Liss, Inc.

  7. Effects of Q-switched and long-pulsed 1064 nm Nd:YAG laser on enlarged facial pores. (United States)

    Lee, Chang Nam; Kim, You Jeong; Lee, Hyun Seung; Kim, Hei Sung


    'Enlarged facial pore' is a subjective term, which is not clearly defined but often complained by many. A diverse range of treatments are used though evidence of efficacy remains largely anecdotal. We report a series of nine patients who underwent a split face trial with Q-switched 1064 nm Nd:YAG and long-pulsed 1064 nm Nd:YAG laser to treat enlarged facial pores.

  8. Laser annealing of ion implanted silicon by the aid of a Q-switched neodymium glass laser

    International Nuclear Information System (INIS)

    Exner, H.; Laemmel, B.; Zscherpe, G.


    Experimental results of laser annealing of arsenic implanted silicon are presented. Different depths of melting are obtained by varying the energy flux density of the Q-switched neodymium glass laser. The annealed samples are studied by the aid of optical microscopy, scanning electron microscopy, Rutherford backscattering spectrometry (RBS) combined with ion channeling, and of resistance measurements. Not any defect could be found by RBS and no surface structure could be determined by microscopy


    Directory of Open Access Journals (Sweden)

    I. N. Dubinkin


    Full Text Available The article deals with a method of numerical simulation of laser oscillation in the radially symmetric unstable resonator with an output variable reflectivity mirror (VRM. Research results of the VRM parameters influence on the spatial and energy properties of the laser radiation are obtained. Numerical simulation of laser oscillation in active and passive Q-switching and comparative analysis of the spatial and energy radiation characteristics is done for these modes.

  10. Microstructure and mechanical changes induced by Q-Switched pulse laser on human enamel with aim of caries prevention (United States)

    Apsari, R.; Pratomo, D. A.; Hikmawati, D.; Bidin, N.


    This study was conducted to determine the effect of Q-Switched Nd: YAG laser energy dose to human enamel caries. The specifications of Q-Switched Nd: YAG laser as followed: wavelength of 1064 nm and 6 ns pulse width. Caries enamel samples taken from human teeth molars of 17-35 ages and the type of media caries. Energy doses used in this study were 723.65 mJ/cm2, 767.72 mJ/cm2, and 1065.515 mJ/cm2; 5 Hz repetition rate, and 20 second exposure time. Samples characterized the surface morphology and the percentage of constituent elements, especially calcium/phosphorus (Ca/P) with FESEM-EDAX. The fraction volume and crystallinity percentage of hydroxyapatite (HA) with XRD and hardness value using Vickers Microhardness Test. The results indicated that exposure of Q-Switched Nd:YAG laser on enamel caries resulting cracks, holes, and melt due to plasma production effects in the surface. Plasma production effect also resulted in micro properties such as percentage of Ca/P was close to normal, the fraction volume and crystallinity percentage of HA went up but did not change the crystal structure (in terms of the lattice structure). The hardness value also rose as linear as exposure energy dose caused by phototermal effect. Based on the results, Q-Switched Nd:YAG laser can be used as contactless drill dental caries replacement candidate with the additional therapy effect such as localized caries in order to avoid the spread, the ratio of Ca/P approaching healthy teeth, the fraction volume and crystallinity percentage of HA rose and established stronger teeth with peak energy dose 1065.515 mJ/cm2.

  11. Optimized fiber delivery system for Q-switched, Nd:YAG lasers

    International Nuclear Information System (INIS)

    Setchell, R.E.


    Interest in the transmission of high intensities through optical fibers is being motivated by an increasing number of applications. Using different laser types and fiber materials, various studies are encountering transmission limitations due to laser-induced damage processes. For a number of years we have been investigating these limiting processes during the transmission of Q-switched, multimode, Nd:YAG laser pulses through step-index, multimode, fused-silica fiber. We have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. This breakdown can result in subtle surface modifications that leave the entrance face more resistant to further breakdown or damage events. Catastrophic fiber damage can also occur as a result of a variety of mechanisms, with damage appearing at fiber entrance and exit faces, within the initial entry segment of the fiber path, and at other internal sites due to fiber fixturing and routing effects. System attributes that will affect breakdown and damage thresholds include laser characteristics, the design and alignment of laser-to-fiber injection optics, and fiber end-face preparation. In the present work we have combined insights gained in past studies in order to establish what thresholds can be achieved if all system attributes can be optimized to some degree. Our multimode laser utilized past modifications that produced a relatively smooth, quasi-Gaussian profile. The laser-to-fiber injection system achieved a relatively low value for the ratio of peak-to-average fluences at the fiber entrance face, incorporated a mode scrambler to generate a broad mode power distribution within the initial segment of the fiber path, and had improved fixturing to insure that the fiber axis was collinear with the incident laser beam. Test fibers were from a particular production lot for which initial-strength characteristics were established and a high-stress proof test was performed

  12. Q-switching and mode-locking pulse generation with graphene oxide paper-based saturable absorber

    Directory of Open Access Journals (Sweden)

    Sulaiman Wadi Harun


    Full Text Available Q-switched and mode-locked erbium-doped fibre lasers (EDFLs are demonstrated by using non-conductive graphene oxide (GO paper as a saturable absorber (SA. A stable and self-starting Q-switched operation was achieved at 1534.4 nm by using a 0.8 m long erbium-doped fibre (EDF as a gain medium. The pulse repetition rate changed from 14.3 to 31.5 kHz, whereas the corresponding pulse width decreased from 32.8 to 13.8 µs as the pump power increased from 22 to 50.5 mW. A narrow spacing dual-wavelength Q-switched EDFL could also be realised by including a photonics crystal fibre and a tunable Bragg filter in the setup. It can operate at a maximum repetition rate of 31 kHz, with a pulse duration of 7.04 µs and pulse energy of 2.8 nJ. Another GOSA was used to realise mode-locked EDFL in a different cavity consisting of a 1.6 m long EDF in conjunction with 1480 nm pumping. The laser generated a soliton pulse train with a repetition rate of 15.62 MHz and pulse width of 870 fs. It is observed that the proposed fibre lasers have a low pulsing threshold pump power as well as a low damage threshold.

  13. Role of Q-switched ND:YAG laser in nevus of Ota: A study of 25 cases

    Directory of Open Access Journals (Sweden)

    Shivangi Sharma


    Full Text Available Background: Nevus of Ota is common condition in Indian patients. The condition is more common in females, with a male-female ratio of 1:4.8. Aim : To evaluate long-term efficacy safety and stability of Q-switched ND:YAG laser in treatment of Nevus of Ota. Design: 6 month follow-up of patients of Nevus of Ota, treated with Q-switched ND:YAG laser Materials and Methods : Twenty-five patients of Nevus of Ota were treated with Q-switched ND:YAG laser for a period of 1 year and 9 months; patient had fitzpatricks skin type 4 and 5; detailed history, clinical examination, ophthalmoscopy, and otoscopy was done in all cases; clinical photographs were taken before and after the completion of treatments. Six-month follow-up was done after the last session. Response to treatment was graded based on physician′s global assessment. Result : More than 70% improvement was seen in 15 patients (60%. Eight patients (32% had moderate and two patients (8% showed mild improvement.

  14. A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser

    Directory of Open Access Journals (Sweden)

    Tianxian Feng


    Full Text Available We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP nanosheets were prepared via a liquid exfoliation approach exploiting N-methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI, a piece of BP–PI film was obtained after evaporating the mixture in a petri dish. The BP–PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP–PI film can act as a promising nonlinear optical device for laser applications.

  15. Switchable Q-switched and modelocked operation in ytterbium doped fiber laser under all-normal-dispersion configuration

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Pranb K., E-mail:; Gupta, Pradeep K.; Singh, Chandra Pal; Singh, Amarjeet; Sharma, Sunil K.; Bindra, Kushvinder S.; Oak, Shrikant M. [Solid State Laser Division, Raja Ramanna Center for Advanced Technology, Indore, M.P. 452013 (India)


    We have constructed an Yb-doped fiber laser in all-normal-dispersion configuration which can be independently operated in Q-switched or modelocked configuration with the help of a simple fiber optic ring resonator (FORR). In the presence of FORR, the laser operates in Q-switched mode producing stable pulses in the range of 1 μs-200 ns with repetition rate in the range of 45 kHz-82 kHz. On the other hand, the laser can be easily switched to mode-locked operation by disjoining the FORR loop producing train of ultrashort pulses of ∼5 ps duration (compressible to ∼150 fs) at ∼38 MHz repetition rate. The transmission characteristics of FORR in combination with the nonlinear polarization rotation for passive Q-switching operation is numerically investigated and experimentally verified. The laser can serve as a versatile seed source for power amplifier which can be easily configured for application in the fields that require different pulsed fiber lasers.

  16. Theoretical and experimental study of a laser-diode-pumped actively Q-switched Yb:NaY(WO4)2 laser with acoustic-optic modulator (United States)

    Zhang, Haikun; Xia, Wei; Song, Peng; Wang, Jing; Li, Xin


    A laser-diode-pumped actively Q-switched Yb:NaY(WO4)2 laser operating at around 1040 nm is presented for the first time with acoustic-optic modulator. The dependence of pulse width on incident pump power for different pulse repetition rates is measured. By considering the Guassian spatial distribution of the intracavity photon density and the initial population-inversion density as well as the longitudinal distribution of the photon density along the cavity axis and the turn off time of the acoustic-optic Q-switch, the coupled equations of the actively Q-switched Yb:NaY(WO4)2 laser are given. The coupled rate equations are used to simulate the Q-switched process of laser, and the numerical solutions agree with the experimental results.

  17. Comparison of Small-Scale Actively and Passively Q-Switched Eye-Safe Intracavity Optical Parametric Oscillators at 1.57 μm

    International Nuclear Information System (INIS)

    Miao Jie-Guang; Pan Yu-Zhai; Qu Shi-Liang


    The first experimental comparison between the actively and passively Q-switched intracavity optical parametric oscillators (IOPOs) at 1.57 μm driven by a small-scale diode-pumped Nd:YVO 4 laser are thoroughly presented. It is found that the performances of the two types of IOPOs are complementary. The actively Q-switched IOPO features a shorter pulse duration, a higher peak power, and a superior power and pulse stability. However, in terms of compactness, operation threshold and conversion efficiency, passively Q-switched IOPOs are more attractive. It is further indicated that the passively Q-switched IOPO at 1.57μm is a promising and cost-effective eye-safe laser source, especially at the low and moderate output levels. In addition, instructional improvement measures for the two types of IOPOs are also summarized. (fundamental areas of phenomenology(including applications))

  18. Minocycline-induced hyperpigmentation: comparison of 3 Q-switched lasers to reverse its effects

    Directory of Open Access Journals (Sweden)

    Nisar MS


    Full Text Available Mahrukh S Nisar,1 Karthik Iyer,1 Robert T Brodell,2 Jenifer R Lloyd,3 Thuzar M Shin,3 Asad Ahmad4 1Northeast Ohio Medical University, Rootstown, OH, USA; 2Division of Dermatology, University of Mississippi Medical Center, Jackson, MS, USA; 3Case Western Reserve University School of Medicine, Cleveland, OH, USA; 4Northside Medical Center, Youngstown, OH, USA Abstract: Minocycline is a tetracycline derivative antibiotic commonly prescribed for acne, rosacea, and other inflammatory skin disorders. Minocycline turns black when oxidized, leading to discoloration of the skin, nails, bulbar conjunctiva, oral mucosa, teeth, bones, and thyroid gland. Hyperpigmentation has been reported after long-term minocycline therapy with at least 100 mg/day. Three types of minocycline-induced cutaneous hyperpigmentation can result. Type I is the most common, and is associated with blue-black discoloration in areas of previous inflammation and scarring. Type II most commonly affects the legs and is characterized by blue-gray pigmentation of previously normal skin. Type III is the least common and is characterized by diffuse muddy-brown discoloration predominantly on sun exposed skin. Minocycline-induced hyperpigmentation may be cosmetically disfiguring and prompt identification is essential. Without treatment, symptoms may take several months, to years to resolve, after discontinuation of the drug. However, the pigmentation may never completely disappear. In fact, there have been few reports of complete resolution associated with any therapeutic intervention. We report a case of a patient on long-term minocycline therapy utilized as an anti-inflammatory agent to control symptoms of rheumatoid arthritis, which led to minocycline-induced hyperpigmentation of the face. To remove the blue-gray cutaneous deposits, 3 Q-switched lasers (Neodymium: yttrium aluminum garnet (Nd:YAG 1064 nm, Alexandrite 755 nm, and Ruby 694 nm were used in test areas. The Alexandrite 755 nm

  19. Radially polarized and passively Q-switched Yb-doped fiber laser based on intracavity birefringent mode discrimination (United States)

    Sun, Xuehuan; Wu, Yongxiao; Chen, Sanbin; Li, Jianlang


    In this paper, we demonstrated a passive Q-switched ytterbium-doped fiber laser with radially polarized beam emission by using a c-cut YVO4 birefringent crystal as the intracavity polarization discriminator, and a Cr4+:YAG crystal as the saturable absorber and output coupler. The maximum averaged laser power reached 3.89 W with a high slope efficiency of 66.5%. The laser pulse had a peak power of 161 W, 160 ns duration, and 151 kHz repetition rate at the absorbed pump power of 6.48 W. Such a radially polarized pulse would facilitate numerous applications.

  20. Compact, Passively Q-Switched Nd:YAG Laser for the MESSENGER Mission to the Planet Mercury (United States)

    Krebs, Danny J.; Novo-Gradac, Anne-Marie; Li, Steven X.; Lindauer, Steven J.; Afzal, Robert S.; Yu, Antony


    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter (MLA) instrument which is an instrument on the MESSENGER mission to the planet Mercury. The laser achieves 5.4 percent efficiency with a near diffraction limited beam. It has passed all space flight environmental tests at system, instrument, and satellite integration. The laser design draws on a heritage of previous laser altimetry missions, specifically ISESAT and Mars Global Surveyor; but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

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

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Zhonglie [Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, California 92612 (United States); Zeng, Lvming; Chen, Zhongping, E-mail:, E-mail: [Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, California 92612 (United States); Kim, Chang-Seok, E-mail:, E-mail: [Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)


    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.

  2. Conductive graphene as passive saturable absorber with high instantaneous peak power and pulse energy in Q-switched regime (United States)

    Zuikafly, Siti Nur Fatin; Khalifa, Ali; Ahmad, Fauzan; Shafie, Suhaidi; Harun, SulaimanWadi


    The Q-switched pulse regime is demonstrated by integrating conductive graphene as passive saturable absorber producing relatively high instantaneous peak power and pulse energy. The fabricated conductive graphene is investigated using Raman spectroscopy. The single wavelength Q-switching operates at 1558.28 nm at maximum input pump power of 151.47 mW. As the pump power is increased from threshold power of 51.6 mW to 151.47 mW, the pulse train repetition rate increases proportionally from 47.94 kHz to 67.8 kHz while the pulse width is reduced from 9.58 μs to 6.02 μs. The generated stable pulse produced maximum peak power and pulse energy of 32 mW and 206 nJ, respectively. The first beat node of the measured signal-to-noise ratio is about 62 dB indicating high pulse stability.

  3. Watt-level passively Q-switched double-cladding fiber laser based on graphene oxide saturable absorber. (United States)

    Yu, Zhenhua; Song, Yanrong; Dong, Xinzheng; Li, Yanlin; Tian, Jinrong; Wang, Yonggang


    A watt-level passively Q-switched ytterbium-doped double-cladding fiber laser with a graphene oxide (GO) absorber was demonstrated. The structure of the GO saturable absorber mirror (GO-SAM) was of the sandwich type. A maximum output power of 1.8 W was obtained around a wavelength of 1044 nm. To the best of our knowledge, this is the highest output power in Q-switched fiber lasers based on a GO saturable absorber. The pure GO was protected from the oxygen in the air so that the damage threshold of the GO-SAM was effectively raised. The gain fiber was a D-shaped ytterbium-doped double-cladding fiber. The pulse repetition rates were tuned from 120 to 215 kHz with pump powers from 3.89 to 7.8 W. The maximum pulse energy was 8.37 μJ at a pulse width of 1.7 μs.

  4. Hollow fiber optics with improved durability for high-peak-power pulses of Q-switched Nd:YAG lasers. (United States)

    Matsuura, Yuji; Tsuchiuchi, Akio; Noguchi, Hiroshi; Miyagi, Mitsunobu


    To improve the damage threshold of hollow optical waveguides for transmitting Q-switched Nd:YAG laser pulses, we optimize the metallization processes for the inner coating of fibers. For silver-coated hollow fiber as the base, second, and third Nd:YAG lasers, drying silver films at a moderate temperature and with inert gas flow is found to be effective. By using this drying process, the resistance to high-peak-power optical pulse radiation is drastically improved for fibers fabricated with and without the sensitizing process. The maximum peak power transmitted in the fiber is greater than 20 MW. To improve the energy threshold of aluminum-coated hollow fibers for the fourth and fifth harmonics of Nd:YAG lasers, a thin silver film is added between the aluminum film and the glass substrate to increase adhesion of the aluminum coating. By using this primer layer, the power threshold improves to 3 MW for the fourth harmonics of a Q-switched Nd:YAG laser light.

  5. Bismuth telluride topological insulator nanosheet saturable absorbers for q-switched mode-locked Tm:ZBLAN waveguide lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiantao; Gross, Simon; Withford, Michael J.; Fuerbach, Alexander [Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) and MQ Photonics Research Centre, Dept. of Physics and Astronomy, Macquarie Univ., NSW (Australia); Zhang, Han; Guo, Zhinan [SZU-NUS Collaborative Innovation Centre for Optoelectronic Science and Technology, Key Lab. of Optoelectronic Devices and Systems of Ministry of Education, College of Optoelectronic Engineering, Shenzhen Univ. (China)


    Nanosheets of bismuth telluride (Bi{sub 2}Te{sub 3}), a topological insulator material that exhibits broadband saturable absorption due to its non-trivial Dirac-cone like energy structure, are utilized to generate short pulses from Tm:ZBLAN waveguide lasers. By depositing multiple layers of a carefully prepared Bi{sub 2}Te{sub 3} solution onto a glass substrate, the modulation depth and the saturation intensity of the fabricated devices can be controlled and optimized. This approach enables the realization of saturable absorbers that feature a modulation depth of 13% and a saturation intensity of 997 kW/cm{sup 2}. For the first time to our knowledge, Q-switched mode-locked operation of a linearly polarized mid-IR ZBLAN waveguide chip laser was realized in an extended cavity configuration using the topological insulator Bi{sub 2}Te{sub 3}. The maximum average output power of the laser is 16.3 mW and the Q-switched and mode-locked repetition rates are 44 kHz and 436 MHz, respectively. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Passively Q-switched mode-locked Nd3+:LuVO4 laser by LT-GaAs saturable absorber

    International Nuclear Information System (INIS)

    Li, M; Zhao, S; Li, Y; Yang, K; Li, G; Li, D; An, J; Li, T; Yu, Z


    By using LT-GaAs as saturable absorber, we have demonstrated the stable Q-switched and mode-locked (QML) Nd:LuVO 4 laser run in a Z-type folded cavity. Nearly 100% modulation depth of mode locking can be obtained as long as the pump power reaches the oscillation threshold. The repetition rate of the passively Q-switched pulse envelops ranges from 37.5 to 139 kHz as the pump power increased from 1.7 to 8.2 W. The mode-locked pulse inside the Q-switched envelop has an estimated pulse width of about 220 ps and a repetition rate of 111 MHz. Under an incident pump power of 8.2 W, the highest pulse energy of 6 μJ of each Q-switched envelope, and the highest peak power about 2.73 kW of Q-switched mode-locked pulses can be obtained

  7. Simultaneous Q-switching and mode-locking in an intracavity frequency doubled diode-pumped Nd:YVO4 / KTP green laser with Cr4+:YAG

    International Nuclear Information System (INIS)

    Mukhopadhyay, P. K.; Ranganathan, K.; George, J.; Nathan, T. P. S.; Alsous, M. B.


    We report intracavity second harmonic (at 532 nm) generation in passively Q-switched mode-locked Nd: YVO4 laser. The width of a typical Q-switched envelope of the mode locked pulses for the green laser was around 65 ± 5 ns and the repetition rate for the mode locked pulses was 400 MHz. The intracavity frequency doubling significantly improves the depth of modulation of the mode locked pulses. The peak power of a single mode locked green pulse near the center of the Q-switched envelope was estimated to be more than 2kw and the average green power was 6 times higher than the CW green power at an incident diode pump power of 6W. (author)

  8. High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues. (United States)

    Yang, Jingwei; Wang, Li; Wu, Xianyou; Cheng, Tingqing; Jiang, Haihe


    An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

  9. A stable dual-wavelength Q-switch using a compact passive device containing photonics crystal fiber embedded with carbon platinum (United States)

    Safaei, R.; Amiri, I. S.; Rezayi, M.; Ahmad, H.


    A compact fiber laser utilizing platinum nanoparticles doped on carbon (Pt/C) embedded in photonic crystal fiber capable of generating a stable Q-switch dual-wavelength is designed and verified. Stable Q-switch pulses, with a repetition rate of 73.6 kHz, pulse width of 1.45 µs and power of 3.8 nJ in two separated wavelengths of 1557.39 nm and 1558.86 nm at a pump power of 350 mW, have been obtained. This is a novel method for generating Q-switch dual-wavelength pulses using a well-protected component that introduces both a saturable absorber and Mach-Zehnder interferometer effects simultaneously in the laser cavity. Furthermore, to best of our knowledge, this is the first time that Pt/C nanoparticles have been used in a saturable absorber for optical pulse generation.

  10. Passively Q-switched self-frequency-doubled Nd3+:GdCa4O(BO3)3 laser

    International Nuclear Information System (INIS)

    Zhang, Xingyu; Zhao, Shengzhi; Wang, Qingpu; Zhang, Shujun; Sun, Lianke; Liu, Xunmin; Zhang, Shaojun; Chen, Huanchu


    The performance of a flash-lamp-pumped self-frequency-doubled Nd 3+ :GdCa 4 O(BO 3 ) 3 (Nd:GdCOB) laser that is passively Q switched with Cr 4+ :YAG saturable absorbers is demonstrated. The maximum 0.53-μm pulse energy obtained is 2.6 mJ, and the maximum peak intensity is 15 MW/cm2. The dependence of the pulse characteristics on the orientation of the saturable absorber and on the cavity length is measured. Meanwhile, the transversal distribution of the intracavity photon density is taken into account in the rate equations for an intracavity frequency-doubled passively Q-switched laser, and the solutions are used to account for the behavior of the passively Q-switched Nd:GdCOB laser. [copyright] 2001 Optical Society of America

  11. Q-switched all-solid-state lasers and application in processing of thin-film solar cell (United States)

    Liu, Liangqing; Wang, Feng


    Societal pressure to renewable clean energy is increasing which is expected to be used as part of an overall strategy to address global warming and oil crisis. Photovoltaic energy conversion devices are on a rapidly accelerating growth path driven by government, of which the costs and prices lower continuously. The next generation thin-film devices are considered to be more efficiency and greatly reduced silicon consumption, resulting in dramatically lower per unit fabrication costs. A key aspect of these devices is patterning large panels to create a monolithic array of series-interconnected cells to form a low current, high voltage module. This patterning is accomplished in three critical scribing processes called P1, P2, and P3. All-solid-state Q-switched lasers are the technology of choice for these processes, due to their advantages of compact configuration, high peak-value power, high repeat rate, excellent beam quality and stability, delivering the desired combination of high throughput and narrow, clean scribes. The end pumped all-solid-state lasers could achieve 1064nm IR resources with pulse width of nanoseconds adopting acoustic-optics Q-switch, shorter than 20ns. The repeat rate is up to 100kHz and the beam quality is close to diffraction limit. Based on this, 532nm green lasers, 355nm UV lasers and 266nm DUV lasers could be carried out through nonlinear frequency conversion. Different wave length lasers are chose to process selective materials. For example, 8-15 W IR lasers are used to scribe the TCO film (P1); 1-5 W green lasers are suitable for scribing the active semiconductor layers (P2) and the back contact layers (P3). Our company, Wuhan Lingyun Photo-electronic System Co. Ltd, has developed 20W IR and 5W green end-pumped Q-switched all-solid-state lasers for thin-film solar industry. Operating in high repeat rates, the speed of processing is up to 2.0 m/s.

  12. 36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations (United States)

    Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.


    A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

  13. Diode-pumped continuous-wave and passively Q-switched Nd:GdLuAG laser at 1443.9 nm (United States)

    Wu, Qianwen; Liu, Zhaojun; Zhang, Sasa; Cong, Zhenghua; Guan, Chen; Xue, Feng; Chen, Hui; Huang, Qingjie; Xu, Xiaodong; Xu, Jun; Qin, Zengguang


    We investigated the 1443.9 nm laser characteristics of Nd:GdLuAG crystal. Diode-end-pumping configuration was employed under both continuous-wave (CW) and passively Q-switched operations. For CW operation, the maximum average output power was 1.36 W with a slope efficiency of 15%. By using a V3+:YAG crystal as the saturable absorber, we obtained the maximum average output power of 164 mW under Q-switched operation. The corresponding pulse energy was 29.3 μJ and pulse duration was 59 ns.

  14. The simultaneous generation of soliton bunches and Q-switched-like pulses in a partially mode-locked fiber laser with a graphene saturable absorber (United States)

    Wang, Zhenhong; Wang, Zhi; Liu, Yan-ge; He, Ruijing; Wang, Guangdou; Yang, Guang; Han, Simeng


    We experimentally report the coexistence of soliton bunches and Q-switched-like pulses in a partially mode-locked fiber laser with a microfiber-based graphene saturable absorber. The soliton bunches, like isolated spikes with extreme amplitude and ultrashort duration, randomly generate in the background of the Q-switched-like pulses. The soliton bunches have some pulse envelopes in which pulses operate at a fundamental repetition rate in the temporal domain. Further investigation shows that the composite pulses are highly correlated with the noise-like pulses. Our work can make a further contribution to enrich the understanding of the nonlinear dynamics in fiber lasers.

  15. Diode-pumped passively Q-switched Nd:GdTaO4 laser based on tungsten disulfide nanosheets saturable absorber at 1066 nm (United States)

    Li, M. X.; Jin, G. Y.; Li, Y.


    In this paper, we investigated the passively Q-switched Nd:GdTaO4 laser based on tungsten disulfide (WS2) saturable absorber (SA). The preparation method of WS2 SA was to attach the WS2-alcohol dispersion onto the quartz substrates. The diode-pumped passively Q-switched Nd:GdTaO4 laser operated at a central wavelength of 1066 nm. The stable pulse output could be obtained at the single pulse width of 560 ns. In a word, WS2 seems to be a suitable saturable absorber for solid state lasers.

  16. 2 and 3 µm passively Q-switched bulk pulse laser based on a MoS2/graphene heterojunction (United States)

    Wang, Xihu; Xu, Jinlong; Sun, Yijian; Feng, Wendou; You, Zhenyu; Sun, Dunlu; Tu, Chaoyang


    We report for the first time that a MoS2/graphene heterojunction can behave as a saturable absorber to realize 2 and 3 µm passively Q-switched bulk lasers. This heterojunction is prepared through a facile hydrothermal method. For the 2 µm laser, a stable pulse is obtained with a pulse duration of 473 ns, output power of 553 mW, pulse energy of 5.267 µJ and repetition rate of 105 kHz. For the 3 µm laser, a pulse duration of 355 ns is observed with an average output power of 112 mW and pulse energy of 0.889 µJ. These results indicate the great potential of MoS2/graphene heterojunctions for realizing mid-infrared pulse lasers.

  17. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser. (United States)

    Goldman, Alberto; Wollina, Uwe


    Permanent makeup is a cosmetic tattoo that is used to enhance one's appearance, and which has become more popular among middle-aged and elderly women. A couple of benefits seem to be associated with permanent tattoos in the elderly: saving time (wake up with makeup); poor eyesight (difficult to apply makeup); and saving money. On the other hand, cosmetic tattoos bear the same risks as other tattoo procedures. We report on fading and unintended hyperpigmentation after tattooing on eyebrows and eyelids, and discuss the scientific and anatomical background behind the possible cause. Dermatochalasis may be a possible risk factor for excessive unwanted discolorations. Q-switched neodymium-doped yttrium aluminum garnet laser is an appropriate and safe therapeutic tool that can manage such adverse effects. Consumer protection warrants better information and education of the risks of cosmetic tattoos - in particular, for elderly women.

  18. Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas T.


    We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode...... with a Mode-Field-Diameter (MFD) of 59 mu m. We further demonstrate high pulse energy Second-Harmonic-Generation (SHG) and Third Harmonic Generation (THG) using a simple Q-switched single-stage rod fiber laser cavity architecture reaching pulse energies up to 1mJ at 515nm and 0.5mJ at 343nm. (C) 2011 Optical...

  19. Highly efficient actively Q-switched Yb:LGGG laser generating 3.26 mJ of pulse energy (United States)

    Li, Yanbin; Zhang, Jian; Zhao, Ruwei; Zhang, Baitao; He, Jingliang; Jia, Zhitai; Tao, Xutang


    An efficient acousto-optic Q-switched laser operation of Yb:(LuxGd1-x)3Ga5O12 (x = 0.062) (Yb:LGGG) crystal is demonstrated, producing stable pulses with repetition rate ranging from 1 to 20 kHz. Under the absorbed pump power of 8.75 W, the maximum average output power of 3.26 W is obtained at the pulse repletion rate of 1 kHz, corresponding to the slope efficiency as high as 52%. The pulse width of 14.5 ns is achieved with the pulse energy and peak power of 3.26 mJ and 225 kW, respectively. It indicates great potential of Yb:LGGG crystal for generating pulsed lasers.

  20. On the densification and hydration of CaCO3 particles by Q-switched laser pulses in water (United States)

    Lin, Peng-Wen; Wu, Chao-Hsien; Zheng, Yuyuan; Chen, Shuei-Yuan; Shen, Pouyan


    Calcite powders subjected to Q-switched laser pulses in water were characterized by X-ray/electron diffraction and optical spectroscopy to have a significant internal compressive stress (up to ca. 1.5 GPa) with accompanied transformation into defective calcite II and hydrates. The defective calcite II particles were (0 1 0), (0 0 1), (0 1¯ 1), (0 1 3) and (0 1¯ 3) faceted with 2×(0 2 0)II commensurate superstructure and tended to hydrate epitaxially as monohydrocalcite co-existing with ikaite (CaCO3·6H2O) with extensive cleavages and amorphous calcium carbonate with porous structure. The colloidal suspension containing the densified calcite polymorphs and hydrates showed two UV-visible absorptions corresponding to a minimum band gap of ca. 5 and 3 eV, respectively.

  1. Treatment of Laugier-Hunziker syndrome with the Q-switched alexandrite laser in 22 Chinese patients. (United States)

    Zuo, Ya-Gang; Ma, Dong-Lai; Jin, Hong-Zhong; Liu, Yue-Hua; Wang, Hong-Wei; Sun, Qiu-Ning


    Laugier-Hunziker syndrome (LHS), a rare, acquired pigmentary disorder of the lips, oral mucosa, and fingers, is known to be an entirely benign disease with no systemic manifestations. In the past, the pigmentation has been treated efficiently in a few patients with the Q-switched neodymium: yttrium-aluminum-garnet (Nd:YAG) laser and the Q-switched alexandrite laser (QSAL). In order to evaluate the efficacy and safety of QSAL on Chinese patients of LHS, we treated 22 patients with QSAL in the past 5 years. Treatments were delivered on a bimonthly or trimonthly basis until the abnormal pigmentation totally disappeared. Patients were evaluated at each visit for evidence of dyspigmentation, scarring, or other untoward effects from the laser treatment. Our 22 subjects consisted of 18 females and 4 males with a mean age of 42.4 years. After only one session of laser treatment, the clearing on the lips was as follow: 18 (81.8%) excellent, 2 (9.1%) good, 1 (4.5%) fair and 1 (4.5%) poor. Eighteen patients (81.8%) with LHS, who had achieved excellent clearing after only one session of laser treatment, did not receive further treatment. Among the left four patients, three patients (13.6%) achieved complete results after three laser treatments. Only one patient required six sessions to achieve complete clearance. No scarring was noted after any of the treatments. The appearance of pigmentation on mucous membranes in a middle-aged patient without a significant family history for skin disorders should prompt consideration for the possible diagnosis of LHS. Our study has also demonstrated QSAL to be highly effective and safe in the treatment of LHS.

  2. Dynamical modeling and experiment for an intra-cavity optical parametric oscillator pumped by a Q-switched self-mode-locking laser (United States)

    Wang, Jing; Liu, Nianqiao; Song, Peng; Zhang, Haikun


    The rate-equation-based model for the Q-switched mode-locking (QML) intra-cavity OPO (IOPO) is developed, which includes the behavior of the fundamental laser. The intensity fluctuation mechanism of the fundamental laser is first introduced into the dynamics of a mode-locking OPO. In the derived model, the OPO nonlinear conversion is considered as a loss for the fundamental laser and thus the QML signal profile originates from the QML fundamental laser. The rate equations are solved by a digital computer for the case of an IOPO pumped by an electro-optic (EO) Q-switched self-mode-locking fundamental laser. The simulated results for the temporal shape with 20 kHz EO repetition and 11.25 W pump power, the signal average power, the Q-switched pulsewidth and the Q-switched pulse energy are obtained from the rate equations. The signal trace and output power from an EO QML Nd3+: GdVO4/KTA IOPO are experimentally measured. The theoretical values from the rate equations agree with the experimental results well. The developed model explains the behavior, which is helpful to system optimization.

  3. All passive synchronized Q-switching of a quasi-three-level and a four-level Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Tidemand-Lichtenberg, Peter; Jensen, Ole Bjarlin


    Using an all passive approach, synchronized Q-switching of two Nd:YAG lasers, at 946 nm and 1064 nm, is reported. Two laser crystals are used to avoid gain competition, and stable operation is reported for the first time. The pulse trains are synchronized over a wide range of pump powers...

  4. Split-face comparison of intense pulsed light and nonablative 1,064-nm Q-switched laser in skin rejuvenation. (United States)

    Huo, Meng-Hua; Wang, Yong-Qian; Yang, Xin


    Multiple nonablative skin rejuvenation techniques have been used to improve facial aging. To compare rejuvenation efficiency of intense pulsed light (IPL) with nonablative 1,064-nm Q-switched laser in Asian patients. Twelve female subjects were enrolled and received five sessions of treatments at 2-week intervals. A split-face study was performed, with IPL applied to the left side of the face and nonablative 1,064-nm Q-switched laser to the right side. All assessments showed significant skin rejuvenation. For the improvement of skin texture, pore size, and sebum secretion, similar efficiency from laser and IPL was observed. For lightening of skin tone and macula, the IPL was more efficient than the laser after the first treatment, although no further clinical improvement resulted after three treatments. The laser gradually lightened the skin tone and macula and was ultimately more efficient than the IPL after five treatments. A series of IPL and nonablative 1,064-nm Q-switched laser treatments were performed with similar efficiency and safety for the improvement in skin texture, pore size, and sebum secretion. IPL was faster, but nonablative 1,064-nm Q-switched laser was more effective in improving skin tone and macula. © 2010 by the American Society for Dermatologic Surgery, Inc.

  5. The regeneration of thermal wound on mice skin (Mus Musculus) after Q-Switch Nd: YAG laser irradiation for cancer therapy candidate (United States)

    Apsari, R.; Nahdliyatun, E.; Winarni, D.


    The aims of this study are to investigate the regeneration of mice skin tissue (Mus Musculus) irradiated by Q-Switch Nd: YAG laser and morphological change due to Q-Switch Nd: YAG laser irradiation compared to conventional heating (hairdryer). The 2-3 month of twenty-seven mice were used for experimental animals. Mice were incised in the dorsum by the damage effect of laser energy dose (therapeutic dose) of 29.5 J/cm2 with 10 seconds of exposure time, 10 Hz of repetition rate, and 100 pulses of the given single pulse energy. The mice skin tissue was injuried by hairdryer to get burned effect. Mice were divided into three groups, Group I (control) were not treated by anything, Group II were treated by Q-Switch Nd: YAG laser irradiation and sacrificed on (0, 1, 3, 5) days, and Group III were treated by hairdryer then sacrificed on (0, 1, 3, 5) days. Pathology examination showed that the energy of 29,5 J/cm2 dose produced the hole effect (ablation) through the hypodermic layer caused by optical breakdown and collagen coagulation. Thus, the 60 °C temperature of burn showed coagulation necrosis because piknosis discovered in the injured area. The regeneration process showed that the mice skin tissue's ability to regenerate was irradiated by fast laser because of the focus of Q-Switch Nd: YAG laser. It was showed by the scab releases on third day and completely reepithelialization formation on the fifth day. The collagen fibers distribution was same as normal skin tissue on day 5 and so did angiogenesis. Therefore, Q-Switch Nd: YAG laser can be applied for problems of dermatology medical therapies, especially melasma, nevus of ota and tatto therapy. For skin cancer therapy application, energy dose of unregenerated skin tissue is chosen because the death expected effect is permanent.

  6. Biostimulative effects of Nd:YAG Q-switch dye on normal human fibroblast cultures: study of a new chemosensitizing agent for the Nd:YAG laser

    International Nuclear Information System (INIS)

    Castro, D.J.; Saxton, R.E.; Fetterman, H.R.; Castro, D.J.; Ward, P.H.


    Kodak Q-switch II is a new chemical with an absorption maxima at 1051 nm, designed to be used as an Nd:YAG dye laser. The potential for this dye as a new chemosensitizing agent in the treatment of connective tissue diseases and wound healing with low energy Nd:YAG laser was examined. Two normal fibroblast cell lines were tested for sensitivity to various levels of this dye in vitro. These cells were exposed to Q-switch II dye at concentrations of 0.01, 0.1, 1, 10, 50, and 100 micrograms/ml for 1 and 24 hours. Cell viability was assessed by the trypan blue exclusion test. Cell duplication and DNA synthesis were measured by the incorporation of [ 3 H]-thymidine at 6 and 24 hours postexposure to Q-switch II dye. At concentrations up to 10 micrograms/ml, both cell lines tested showed no changes in cell viability. However, at concentrations equal or higher than 50 micrograms/ml, more than 40% of the fibroblasts incorporated trypan blue after 24 hours of exposure to this dye, indicating significant cell destruction. The results indicate that Q-switch II dye is nontoxic to normal human fibroblast cultures and showed significant biostimulative effects on cell duplication at concentrations equal to or lower than 10 micrograms/ml. Further studies will be required to determine the usefulness of Q-switch II dye as a new photochemosensitizing agent for potential biostimulation of wound healing and/or treatment of connective tissue diseases with the Nd:YAG laser (near infrared, 1060 nm) at nonthermal levels of energies

  7. Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy (United States)

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


    Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

  8. A retrospective analysis of the influencing factors and complications of Q-switched lasers in tattoo removal in China. (United States)

    Zhang, Mengli; Gong, Xiangdong; Lin, Tong; Wu, Qiuju; Ge, Yiping; Huang, Yuqing; Ge, LiYu


    Q-switched (QS) lasers are the gold standard for tattoo removal. The purpose of the present study was to gain a more comprehensive understanding of the factors that influence the efficacy of QS lasers and their associated complications in the removal of tattoos in China. Clinical data of 266 patients were analyzed retrospectively. The tattoo clearance rate was evaluated using the 4-point scale. The Cox regression model was applied to analyze the factors that affected the efficacy of QS lasers in tattoo removal. In addition, treatment-related adverse reactions were analyzed. The results showed that several variables had a statistically significant effect (p tattoo removal treatment, including the patients' age, the tattoo's age, type, color, or ink density and the number of treatments. A variety of adverse responses occurred during the laser treatment. The overall incidence of adverse responses was approximately 24.06%, including pigmentation, hypopigmentation, bulla formation, allergic reactions, and skin texture changes or hypertrophic scarring. Some factors may influence the efficacy of QS lasers in the treatment of tattoos and certain adverse reactions may occur during this process.

  9. Photobiomodulation therapy on wound treatment subsequent to Q-switched Nd: YAG laser tattoo removal in rat model. (United States)

    Imrigha, Nada Abusalah Almabrouk; Bidin, Noriah; Lau, Pik Suan; Musa, Nurfatin; Zakaria, Nurlaily; Krishnan, Ganesan


    Q-switched Nd: YAG laser is the most effective laser for tattoo removal. Photobiomodulation (PBM) therapy is an alternative method applied to accelerate the wound healing. This paper investigated the effects of PBM therapy using 808 nm diode laser on tattooed skin after laser tattoo removal. Forty-five rats were selected and tattooed with black ink on their dorsal, and then distributed into three groups. G0 was received non-laser irradiation. G1 was treated by laser tattoo removal using 1064 nm with energy density of 3.4 J/cm 2 without PBM therapy, while G2 was treated daily with PBM therapy using 808 nm diode laser of 5 J/cm 2 after a single session of laser tattoo removal. The effects of tattoo removal and healing progress of the wound were analyzed using histological studies. Findings showed 808 nm laser promotes the healing process through enhancing epithelialization and collagen deposition. Moreover, PBM therapy stimulated immune cells to improve phagocytosis process for removing the tattoo ink fragments effectively. The PBM therapy treated group was capable of improving the healing process and increasing the quality of skin following the laser tattoo removal. It was also found that stimulation of cellular function by PBM therapy increased tattoo clearance efficiency. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Performance of continuous wave and acousto-optically Q-switched Tm, Ho: YAP laser pumped by diode laser (United States)

    Li, Guoxing; Xie, Wenqiang; Yang, Xining; Zhang, Ziqiu; Zhang, Hongda; Zhang, Liang


    A two-end-pumped a-cut Tm(0.5%), Ho(0.5%):YAP laser output at 2119nm is reported under cryogenic temperature. The maximum output power reached to 7.76W with the incident pump power of 24.2W in CW mode. With the acousto-optically Q-switch, an average power of 7.3W can be obtained, when the pulse repetition frequency was 7.5 kHz. The corresponding optical-to-optical conversion efficiency was 30.2% and the slope efficiency was 31.4%. Then, the laser output characteristics in the repetition frequency of 7.5 kHz and 10kHz were researched. The output power, the optical-to-optical conversion efficiency and slope efficiency were increased with the increase of the repetition frequency. In the same repetition frequency, the pulse duration was decreasing with the growth of the incident pump power.

  11. Nerve fiber layer (NFL) degeneration associated with acute q-switched laser exposure in the nonhuman primate (United States)

    Zwick, Harry; Zuclich, Joseph A.; Stuck, Bruce E.; Gagliano, Donald A.; Lund, David J.; Glickman, Randolph D.


    We have evaluated acute laser retinal exposure in non-human primates using a Rodenstock scanning laser ophthalmoscope (SLO) equipped with spectral imaging laser sources at 488, 514, 633, and 780 nm. Confocal spectral imaging at each laser wavelength allowed evaluation of the image plane from deep within the retinal vascular layer to the more superficial nerve fiber layer in the presence and absence of the short wavelength absorption of the macular pigment. SLO angiography included both fluorescein and indocyanine green procedures to assess the extent of damage to the sensory retina, the retinal pigment epithelium (RPE), and the choroidal vasculature. All laser exposures in this experiment were from a Q-switched Neodymium laser source at an exposure level sufficient to produce vitreous hemorrhage. Confocal imaging of the nerve fiber layer revealed discrete optic nerve sector defects between the lesion site and the macula (retrograde degeneration) as well as between the lesion site and the optic disk (Wallerian degeneration). In multiple hemorrhagic exposures, lesions placed progressively distant from the macula or overlapping the macula formed bridging scars visible at deep retinal levels. Angiography revealed blood flow disturbance at the retina as well as at the choroidal vascular level. These data suggest that acute parafoveal laser retinal injury can involve both direct full thickness damage to the sensory and non-sensory retina and remote nerve fiber degeneration. Such injury has serious functional implications for both central and peripheral visual function.

  12. Effects of adding metals to MoS2 in a ytterbium doped Q-switched fiber laser (United States)

    Khaleque, Abdul; Liu, Liming


    Molybdenum disulfide (MoS2) is widely used in lubricants, metallic alloys and in electronic and optical components. It is also used as saturable absorbers (SAs) in lasers (e.g. fiber lasers): a simple deposition of MoS2 on the fiber end can create a saturable absorber without the necessity of extensive alignment of the optical beam. In this article, we study the effects of adding different metals (Cr, Au, and Al) to MoS2 in a ytterbium (Yb)-doped Q-switched fiber laser. Experimental results show that the addition of a thin layer of gold and aluminium can reduce pulse durations to about 5.8 μs and 8.5 μs, respectively, compared with pure MoS2 with pulse duration of 12 μs. Experimental analysis of the combined metal and MoS2 based composite SAs can be useful in fiber laser applications where it may also find applications in medical, three dimensional (3D) active imaging and dental applications.

  13. High speed ink aggregates are ejected from tattoos during Q-switched Nd:YAG laser treatments. (United States)

    Murphy, Michael J


    Dark material has been observed embedded within glass slides following Q-switched Nd:YAG laser treatment of tattoos. It appears that these fragments are ejected at high speed from the skin during the treatment. Light microscopic analysis of the slides reveals aggregates of dark fragmented material, presumably tattoo ink, with evidence of fractured/melted glass. Photomicrographs reveal that the sizes of these aggregates are in the range 12 μm to 0.5 mm. Tattoo ink fragments were clearly observed on the surface and embedded within glass slides. Surface aggregates were observed as a fine dust and were easily washed off while deeper fragments remained in situ. The embedded fragments were not visible to the unaided eye. Some fragments appeared to have melted yielding an "insect-like" appearance. These were found to be located between approximately 0.2 and 1 mm deep in the glass. Given the particle masses and kinetic energies attained by some of these aggregates their velocities, when leaving the skin, may be hundreds to thousands of metres per second. However, the masses of the aggregates are minuscule meaning that laser operators may be subjected to these high-speed aggregates without their knowledge. These high-speed fragments of ink may pose a contamination risk to laser operators. Lasers Surg. Med. 9999:1-7, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  14. In vitro effect of Q-switched Nd:YAG laser exposure on morphology, hydroxyapatite composition and microhardness properties of human dentin

    Directory of Open Access Journals (Sweden)

    Retna Apsari


    Full Text Available Background: A Q-switched Nd:YAG laser was employed as a source of ablation. The fundamental wavelength of the laser is 1064 nm, with pulse duration of 8 nanosecond operates with uniphase mode of TEM00. In the following experiments, dentin samples (without caries and plaque are exposed to pulse laser with Q-switching effect at various energy dose. Purpose: The aim of this study was to investigate the effect of laser ablation on dentin samples using Q-switched Nd:YAG laser exposure. Methods: The laser was operated in repetitive mode with frequency of 10 Hz. The energy dose of the laser was ranging from 13.9 J/cm2, 21.2 J/cm2 and 41.7 J/cm2. The target material comprised of human dentin. The laser was exposed in one mode with Q-switched Nd:YAG laser. Energy delivered to the target through free beam technique. The exposed human dentin was examined by using x-ray diffraction (XRD and fluoresence scanning electron microscopy for energy dispersive (FESEM-EDAX. Microhardness of human dentin were examined by using microhardness vickers test (MVT. Results: The result obtained showed that the composition of hydroxyapatite of the dentin after exposed by Q-switched Nd:YAG laser are 75.02% to 78.21%, with microhardness of 38.7 kgf/mm2 to 86.6 kgf/mm2. This indicated that exposed pulsed Nd:YAG laser on the human dentin attributed to the phototermal effect. The power density created by the Q-switched Nd:YAG laser enables the heat to produce optical breakdown (melting and hole associated with plasma formation and shock wave propagation, from energy dose of 21.2 J/cm2. From XRD analysis showed that the exposure of Nd:YAG laser did not involve in changing the crystal structure of the dentin, but due to photoablation effect. Conclusion: In conclusion, the application of Q-switched Nd:YAG laser as contactless drills in dentistry should be regarded as an alternative to the classical mechanical technique to improve the quality of the dentin treatment.Latar belakang

  15. Comparison of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet laser for treatment of cosmetic tattoos containing titanium and iron in an animal model. (United States)

    Wang, Chia-Chen; Huang, Chuen-Lin; Yang, An-Hang; Chen, Chih-Kang; Lee, Shao-Chen; Leu, Fur-Jiang


    Cosmetic tattoos contain titanium and ferric oxide and darken through reduction after Q-switched laser irradiation. The optimal treatment for removing these pigments remains unknown. To compare the effects of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet (SP Er:YAG) laser to remove cosmetic tattoos in an animal model. Rats were tattooed using white, flesh-colored, and brown inks (4 bands of each color) on their backs. For each color, one band was left untreated, and one each was treated with a Q-switched neodymium-doped YAG laser, a Q-switched alexandrite laser, and a SP Er:YAG laser every 3 weeks until the pigments were clear. The two Q-switched lasers were equally effective; all three pigments darkened initially and then resolved gradually. Up to 20, 18, and 10 sessions were required to remove white, flesh-colored, and brown tattoos, respectively. Only six sessions were required with the SP Er:YAG laser. Minimal scarring was observed with all lasers. Skin biopsies confirmed pigment granule fragmentation after Q-switched laser treatment and a decrease in the amount of pigment after SP Er:YAG laser treatment. The SP Er:YAG laser was superior to the Q-switched lasers for removing cosmetic tattoos. © 2010 by the American Society for Dermatologic Surgery, Inc.

  16. Bindi tattoo on forehead: success with modified R-20 technique using low fluence q-switched nd yag laser: a case report. (United States)

    Zawar, Vijay; Sarda, Aarti; De, Abhishek


    Bindi tattoo on the forehead, is one of the cultural practice in Indian women from rural areas. Many patients are not pleased with the appearance of their tattoo and thus seek removal. The development of quality-switched lasers has revolutionized the removal of unwanted tattoos. However, despite multiple treatment sessions, the efficacy is often found to be limited. We herein report a case of green-blue bindi tattoo which failed to clear after 8 sessions of Q-switched Nd YAG laser. The tattoo significantly cleared with R-20 method using low fluence Q-switched Nd YAG Laser. R-20 technique seems to be an effective method of tattoo removal and might be a boon for patients who are reluctant to pursue laser treatment because of fear of expenditure, side effects and uncertainty of result. We report efficacy of R-20 technique for a bindi tattoo on forehead.

  17. Tunable Q-switched erbium doped fiber laser based on metal transition oxide saturable absorber and refractive index characteristic of multimode interference effects (United States)

    Mohammed, D. Z.; Khaleel, Wurood Abdulkhaleq; Al-Janabi, A. H.


    Ferro-oxide (Fe3O4) nanoparticles were used as a saturable absorber (SA) for a passively Q-switched erbium doped fiber laser (EDFL) with ring cavity. The Q-switching operation was achieved at a pump threshold of 80 mW. The proposed fiber laser produces stable pulses train of repetition rate ranging from 25 kHz to 80 kHz as the pump power increases from threshold to 342 mW. The minimum recorded pulse width was 2.7 μs at 342 mW. The C-band tunability operation was performed using single mode-multimode-single mode fiber (SM-MM-SM) structure. The laser exhibited a total tuning range of 7 nm, maximum sensitivity of 106.9 nm, optical signal to noise ratio (OSNR) of 38 dB and 3-dB linewidth of 0.06 nm.

  18. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media (United States)

    Woodruff, Steven D.; Mcintyre, Dustin L.


    A device for Laser based Analysis using a Passively Q-Switched Laser comprising an optical pumping source optically connected to a laser media. The laser media and a Q-switch are positioned between and optically connected to a high reflectivity mirror (HR) and an output coupler (OC) along an optical axis. The output coupler (OC) is optically connected to the output lens along the optical axis. A means for detecting atomic optical emission comprises a filter and a light detector. The optical filter is optically connected to the laser media and the optical detector. A control system is connected to the optical detector and the analysis electronics. The analysis electronics are optically connected to the output lens. The detection of the large scale laser output production triggers the control system to initiate the precise timing and data collection from the detector and analysis.

  19. Tunable continuous wave and passively Q-switched Nd:LuLiF4 laser with monolayer graphene as saturable absorber

    International Nuclear Information System (INIS)

    Wang, Feng; Luo, Jianjun; Li, Shixia; Li, Tao; Li, Ming


    Tunable continuous wave and passively Q-switched Nd:LuLiF 4 laser performances were demonstrated. Employing a 2 mm thick quartz plate as the birefringence filter, three continuous tuning ranges from 1045.2 to 1049.9 nm, 1051 to 1055.1 nm and 1072.1 to 1074.3 nm could be obtained. Q-switched laser operation was realized by using a monolayer graphene as a saturable absorber. At an incident pump power of 5.94 W, the maximum average output power was 669 mW with the pulse duration of 210 ns and the pulse repetition rate of 145 kHz at T = 10%. (paper)

  20. High-energy azimuthally polarized laser beam generation from an actively Q-switched Nd:YAG laser with c-cut YVO4 crystal (United States)

    Guo, Jing; Zhang, Baofu; Jiao, Zhongxing; He, Guangyuan; Wang, Biao


    A high-energy, azimuthally polarized (AP) and actively Q-switched Nd:YAG laser is demonstrated. The thermal bipolar lensing effect in the Nd:YAG laser rod is used as a polarization discriminator, and a c-cut YVO4 crystal is inserted into the laser cavity to increase the mode-selecting ability of the cavity for AP mode. The laser generated AP pulses with maximum pulse energy as high as 4.2 mJ. To the best of our knowledge, this is the highest pulse energy obtained from an actively Q-switched AP laser. The pulse energy remained higher than 1 mJ over a wide range of repetition rates from 5 kHz to 25 kHz.

  1. Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser (United States)

    Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi


    In this work, we fabricate the Mo0.5W0.5S2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo0.5W0.5S2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm‑2. The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo0.5W0.5S2 SAs.

  2. End-pumped Nd:YAG Q-switched laser with high energy and narrow pulse for glass carving (United States)

    Ling, Ming; Jin, Guang-yong; Tan, Xue-chun; Wu, Zhi-chao; Liang, Zhu


    In order to raise the accuracy of glass carving and improve deep cutting, a novel diode end-pumed solid-state laser is researched. Selecting proper volume of laser crytal, one continue wave laser diode which longitudinally pumped Nd:YAG crystal is performed and an applied optics coupling system is designed with self focusing.Computing with ray trace software and MATLAB software, the best parameter is obtained, so pumping beam is coupled efficiently to Nd:YAG.Used a Cr4+:YAG crystal with the singnal transmission of 82% and a line plane-concave cavity, nanosecond narrow pulse is gotten. After two thermal-electrical coolers kept the laser to work at constant temperature instead of water cooling, the volume of laser is markedly reduced. The method of thermal-electrical cooling could increase the system efficiency,achieve the effect of low mode output.Experimental results indicate that the maximum laser output energy in 1064 nm is 118mJ,pulse width is 5 ns, conversion efficiency from light to light is 15.7% under the condition of the incident power of 5 W and the diameter of the output laser spot is less than 1 mm. This end-pumped Nd:YAG Q-switched laser with the light output of high quality and long life, which has 0.01 mm accuracy after lens focusing can satisfy the glass carving with higher precision, rapid speed as well as easy control. It can be used in carving all kinds of glass and replace current CO2 laser.

  3. Fractional CO2 laser is as effective as Q-switched ruby laser for the initial treatment of a traumatic tattoo. (United States)

    Seitz, Anna-Theresa; Grunewald, Sonja; Wagner, Justinus A; Simon, Jan C; Paasch, Uwe


    Q-switched laser treatments are considered the standard method for removing both regular and traumatic tattoos. Recently, the removal of tattoo ink using ablative fractional lasers has been reported. Ablative fractional CO2 laser and q-switched ruby laser treatments were used in a split-face mode to compare the safety and efficacy of the two types of laser in removing a traumatic tattoo caused by the explosion of a firework. A male patient suffering from a traumatic tattoo due to explosive deposits in his entire face was subjected to therapy. A series of eleven treatments were performed. The right side of the face was always treated using an ablative fractional CO2 laser, whereas the left side was treated only using a q-switched ruby laser. After a series of eleven treatments, the patient demonstrated a significant lightening on both sides of his traumatic tattoo, with no clinical difference. After the first six treatments, the patient displayed greater lightening on the right side of his face, whereas after another five treatments, the left side of the patient's face appeared lighter. No side effects were reported. In the initial stage of removing the traumatic tattoo, the ablative fractional laser treatment appeared to be as effective as the standard ruby laser therapy. However, from the 6th treatment onward, the ruby laser therapy was more effective. Although ablative fractional CO2 lasers have the potential to remove traumatic tattoos, they remain a second-line treatment option.

  4. Dual-wavelength mid-infrared CW and Q-switched laser in diode end-pumped Tm,Ho:GdYTaO4 crystal (United States)

    Wang, Beibei; Gao, Congcong; Dou, Renqin; Nie, Hongkun; Sun, Guihua; Liu, Wenpeng; Yu, Haijuan; Wang, Guoju; Zhang, Qingli; Lin, Xuechun; He, Jingliang; Wang, Wenjun; Zhang, Bingyuan


    Dual-wavelength continuous-wave and Q-switched lasers are demonstrated in a Tm,Ho:GdYTaO4 crystal under 790 nm laser diode end pumping for the first time to the best of our knowledge. The laser operates with a dual wavelength at 1949.677 nm and 2070 nm for continuous-wave with a spacing of about 120 nm. The maximum output power is 0.332 W with a pump power of 3 W. By using graphene as the saturable absorber, a passively Q-switched operation is performed with a dual-wavelength at 1950.323 nm and 2068.064 nm with a wavelength interval of about 118 nm. The maximum average output power of the Q-switched laser goes up to 200 mW with a minimum pulse duration of 1.2 µs and a maximum repetition rate of 34.72 kHz.

  5. Passively Q-switched dual-wavelength thulium-doped fiber laser based on a multimode interference filter and a semiconductor saturable absorber (United States)

    Wang, M.; Huang, Y. J.; Ruan, S. C.


    In this paper, we have demonstrated a theta cavity passively Q-switched dual-wavelength fiber laser based on a multimode interference filter and a semiconductor saturable absorber. Relying on the properties of the fiber theta cavity, the laser can operate unidirectionally without an optical isolator. A semiconductor saturable absorber played the role of passive Q-switch while a section of single-mode-multimode-single-mode fiber structure served as an multimode interference filter and was used for selecting the lasing wavelengths. By suitably manipulating the polarization controller, stable dual-wavelength Q-switched operation was obtained at ~1946.8 nm and ~1983.8 nm with maximum output power and minimum pulse duration of ~47 mW and ~762.5 ns, respectively. The pulse repetition rate can be tuned from ~20.2 kHz to ~79.7 kHz by increasing the pump power from ~2.12 W to ~5.4 W.

  6. Sclerosis and the Nd:YAG, Q-switched laser with multiple frequency for treatment of telangiectases, reticular veins, and residual pigmentation. (United States)

    Cisneros, J L; Del Rio, R; Palou, J


    The combination of low concentrations of sclerosing solution and the Nd:YAG, Q-switched laser with multiple (quadruple) frequency provides good results in the treatment of telangiectases and reticular varicose veins of the lower extremities, as well as pigmentation that may appear during sclerotherapy. This paper is based on a series of patients with telangiectases and reticular veins who were treated with sclerotherapy and the Nd:YAG, Q-switched laser with quadruple frequency. Patients with telangiectases and reticular veins received two or three treatment sessions with polydocanol and the Nd:YAG, Q-switched laser with quadruple frequency. Then, they were assessed a clinical score corresponding to the level of improvement achieved. Residual hematic pigmentation lesions were also eliminated with the laser. Excellent improvement was evident in 90% of the patients with minimal residual lesions. The combined technique of sclerosing solution and the Nd:YAG laser with multiple frequency is a valid alternative for the elimination of telangiectases and reticular veins of the lower limbs. This technique has several advantages, such as the use of low concentrations of sclerosing solution, high patient acceptance levels due to minimal disturbances, and the fact that local anesthesia is unnecessary. Good results are obtained without complications and minimal residual pigmentation. These mild pigmentation can be treated with the Nd:YAG laser.

  7. Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials. (United States)

    Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R; Hao, Xiaotao; Chen, Feng


    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO 4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO 2 ). The unique feature of VO 2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO 4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO 2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS 2 ) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO 2 as low-cost saturable absorber for subnanosecond laser generation.

  8. Complete resolution of minocycline pigmentation following a single treatment with non-ablative 1550-nm fractional resurfacing in combination with the 755-nm Q-switched alexandrite laser. (United States)

    Vangipuram, Ramya K; DeLozier, Whitney L; Geddes, Elizabeth; Friedman, Paul M


    Pigmentation secondary to minocycline ingestion is an uncommon adverse event affecting 3.7-14.8% of treated individuals for which few effective therapies are available. Three patterns of minocycline pigmentation have a characteristic clinical and histological appearance. The pigment composition in each variety is different and occurs at varying skin depths. Accordingly, a tailored approach according to the type of minocycline pigmentation is crucial for treatment success. The purpose of this intervention was to evaluate the efficacy of non-ablative fractional photothermolysis in combination with the Q-switched alexandrite laser for the treatment of type I minocycline pigmentation on the face. A patient with type I minocycline pigmentation was treated with non-ablative 1550-nm fractional photothermolysis followed immediately by 755-nm Q-switched alexandrite laser and then observed clinically to determine the outcome of this modality. The patient was seen in clinic 1 month later following her single treatment session and 100% clearance of all blue facial pigment was observed. Non-ablative fractional photothermolysis in combination with the 755-nm Q-switched alexandrite laser should be considered for treatment of type I minocycline pigmentation. © 2015 Wiley Periodicals, Inc.

  9. Mid-infrared Fe2+:ZnSe semiconductor saturable absorber mirror for passively Q-switched Er3+-doped ZBLAN fiber laser

    Directory of Open Access Journals (Sweden)

    Shougui Ning


    Full Text Available A mid-infrared (mid-IR semiconductor saturable absorber mirror (SESAM based on Fe2+:ZnSe for passively Q-switched Er3+-doped ZBLAN fiber laser has been demonstrated. Fe2+:ZnSe SESAM was fabricated by electron beam evaporation method. Fe2+ was innovatively doped into the reflective Bragg stack, in which ZnSe layer served as both doped matrix and high refractive layer during the fabricating process. By using the Fe2+:ZnSe SESAM, stable passively Q-switched pulses with the minimum pulse width of 0.43 μs under a repetition rate of 160.82 kHz were obtained. The recorded maximum average output power of 873 mW with a peak power of 12.59 W and pulse energy of 5.43 μJ were achieved. The results demonstrated a new method for fabricating Fe2+:ZnSe SESAM, which can be used in compact mid-IR Q-switched fiber laser.

  10. A rapid tattoo removal technique using a combination of pulsed Er:YAG and Q-Switched Nd:YAG in a split lesion protocol. (United States)

    Sardana, Kabir; Ranjan, Rashmi; Kochhar, Atul M; Mahajan, Khushbu Goel; Garg, Vijay K


    Tattoo removal has evolved over the years and though Q-switched laser is the 'workhorse' laser, it invariably requires multiple sittings, which are dependent on numerous factors, including the skin colour, location of the tattoo, age of the tattoo, colour of pigment used, associated fibrosis and the kind of tattoo treated. Though ablative lasers, both pulsed CO2 and Er:YAG, have been used for recalcitrant tattoos, very few studies have been done comparing them with pigment-specific lasers. Our study was based on the premise that ablating the epidermis overlying the tattoo pigment with Er:YAG could help in gaining better access to the pigment which would enable the Q-switched laser to work effectively with less beam scattering. A study of rapid tattoo removal (RTR) technique using a combination of pulsed Er:YAG and Q-Switched Nd:YAG in a split lesion protocol. This prospective study was undertaken during 2010-13 at a laser Clinic in the Maulana Azad Medical College, New Delhi. A total of 10 patients were recruited, 5 of amateur tattoo and 5 of professional tattoo. After informed consent each tattoo was arbitrarily 'split' into two parts. One part was treated with QS Nd:YAG laser(1064 nm) and the other part with Er:YAG laser immediately followed by the QS Nd:YAG. The laser treatments were repeated at 6-week intervals until the tattoo pigment had cleared. On the combination side in subsequent sittings only the QS Nd:YAG was used, to minimize repetitive ablation. To ensure consistency in the intervention methods a trained dermatologist who was independent of the treatment delivery randomly rated 10% of the procedures. The mean improvement achieved by the Q-switched laser (2.93) was less than the combination laser (3.85) side (p = 0.001) and needed more sessions (3.8 vs. 1.6; p = 0.001). There was a statistically significant difference in the improvement on the combination side till the second session. On the combination side patients required a maximum of 2 sessions

  11. Effects of tattoo ink's absorption spectra and particle size on cosmetic tattoo treatment efficacy using Q-switched Nd:YAG laser. (United States)

    Leu, Fur-Jiang; Huang, Chuen-Lin; Sue, Yuh-Mou; Lee, Shao-Chen; Wang, Chia-Chen


    The mechanisms responsible for variable responses of cosmetic tattoos to Q-switched laser removal treatment remain unclear. We sought to investigate the properties of tattoo inks that may affect the efficacy of laser-assisted tattoo removal. The absorption of white, brown, and black inks before and after Q-switched neodymium-doped yttrium aluminum garnet laser irradiation were analyzed by a reflectance measurement system. Rats were tattooed using the three inks and treated with the same laser for two sessions. Skin biopsies were taken from the treated and untreated sites. Black ink showed strong absorption, reduced after laser irradiation, over the entire spectrum. White ink had low absorption over the visible light spectrum, and brown ink had strong absorption at 400-550 nm wavelengths. White and brown inks turned dark after laser exposure, and the absorption of laser-darkened inks were intermediate between their original color and black ink. White, brown, and black tattoos in rat skin achieved poor, fair to good, and excellent responses to laser treatment, respectively. Transmission electron microscopy showed that white tattoo particles were the largest, brown were intermediate, and black were the smallest before laser. After laser treatment, white and brown tattoo particles were mixtures of large and small particles, while black particles showed overall reduction in number and size. Black tattoo ink's excellent response to Q-switched lasers was associated with its strong absorption and small particle size. White tattoo ink's poor response was associated with its poor absorption, even after laser darkening, and large particle size.

  12. Diode-Pumped Quasi-Three-Level Passively Q-Switched Nd:GGG Laser with a Codoped Nd,Cr:YAG Saturable Absorber

    International Nuclear Information System (INIS)

    Kun-Na, He; Chun-Qing, Gao; Zhi-Yi, Wei; Qi-Nan, Li; Zhi-Guo, Zhang; Hai-He, Jiang; Shao-Tang, Yin; Qing-Li, Zhang


    We demonstrate the first quasi-three-level passively Q-switched Nd:GGG laser at 937 nm using a Nd,Cr:YAG crystal as the saturable absorber. The dependences of the average output power, the repetition rate and the pulse width on the incident pump power are obtained. A maximum average output power of 1.18 W with repetition rate of 35 kHz and pulse width of 45 ns is achieved at an incident pump power of 18.3 W. The corresponding optical-to-optical and slope efficiencies are 6% and 10%, respectively

  13. Solitary pulse-on-demand production by optical injection locking of passively Q-switched InGaN diode laser near lasing threshold

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, X., E-mail:, E-mail:; Stadelmann, T.; Grossmann, S.; Hoogerwerf, A. C.; Boïko, D. L., E-mail:, E-mail: [Centre Suisse d' Electronique et de Microtechnique SA (CSEM), CH-2002 Neuchâtel (Switzerland); Sulmoni, L.; Lamy, J.-M.; Grandjean, N. [Institute of Condensed Matter Physics (ICMP), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)


    In this letter, we investigate the behavior of a Q-switched InGaN multi-section laser diode (MSLD) under optical injection from a continuous wave external cavity diode laser. We obtain solitary optical pulse generation when the slave MSLD is driven near free running threshold, and the peak output power is significantly enhanced with respect to free running configuration. When the slave laser is driven well above threshold, optical injection reduces the peak power. Using standard semiconductor laser rate equation model, we find that both power enhancement and suppression effects are the result of partial bleaching of the saturable absorber by externally injected photons.

  14. Study of simultaneous q-switching and mode-locking in ND:YVO4 laser with Cr4+:YAG crystal

    International Nuclear Information System (INIS)

    Al-Sous, M. B.


    A numerical model of rate equations for a four-level solid-state laser with Cr 4+ :YAG saturable absorber including excited state absorption ESA is presented. The cavity is divided into a large number of disks and the model is solved for each disk and its local corresponding photon flux. The flux array is shifted for each recurrence simulating the movement of photons inside the cavity during the round trip. This simulator can describe the mode locking phenomenon and can be used to simulate the simultaneous mode locking and Q-switching with a saturable absorber. (author)

  15. Short-Pulse-Width Repetitively Q-Switched ~2.7-μm Er:Y2O3 Ceramic Laser

    Directory of Open Access Journals (Sweden)

    Xiaojing Ren


    Full Text Available A short-pulse-width repetitively Q-switched 2.7-μm Er:Y2O3 ceramic laser is demonstrated using a specially designed mechanical switch, a metal plate carved with slits of both slit-width and duty-cycle optimized. With a 20% transmission output coupler, stable pulse trains with durations (full-width at half-maximum, FWHM of 27–38 ns were generated with a repetition rate within the range of 0.26–4 kHz. The peak power at a 0.26 kHz repetition rate was ~3 kW.

  16. Study of simulations q-switching and mode-locking in Nd:YVO4 laser with Cr4+:YAG crystal

    International Nuclear Information System (INIS)

    Al-Sous, M. B.


    A numerical model of rate equations for a four-level solid-state laser with Cr 4+ :YAG saturable absorber including excited state absorption ESA is presented. The cavity is divided into a large number of disks and the model is solved for each disk and its local corresponding photon flux. The flux array is shifted for each recurrence simulating the movement of photons inside the cavity during the round trip. This simulator can describe the mode locking phenomenon and can be used to simulate the simultaneous mode locking and Q-switching with a saturable absorber.(author)

  17. Mid-infrared source with 0.2 J pulse energy based on nonlinear conversion of Q-switched pulses in ZnGeP2. (United States)

    Haakestad, Magnus W; Fonnum, Helge; Lippert, Espen


    Mid-infrared (3-5 μm) pulses with high energy are produced using nonlinear conversion in a ZnGeP(2)-based master oscillator-power amplifier, pumped by a Q-switched cryogenic Ho:YLF oscillator. The master oscillator is based on an optical parametric oscillator with a V-shaped 3-mirror ring resonator, and the power amplifier is based on optical parametric amplification in large-aperture ZnGeP(2) crystals. Pulses with up to 212 mJ energy at 1 Hz repetition rate are obtained, with FWHM duration 15 ns and beam quality M(2) = 3.

  18. Comparison of Q-switched Nd:YAG laser alone versus its combination with ultrapulse CO2 laser for the treatment of black tattoo. (United States)

    Vanarase, Mithila; Gautam, Ram Krishan; Arora, Pooja; Bajaj, Sonali; Meena, Neha; Khurana, Ananta


    Q-switched lasers are conventionally used for the treatment of black tattoo. However, they require multiple sittings, and the response may be slow due to competing epidermal pigment in dark skin. To compare the efficacy of Q-switched Nd:YAG laser alone with its combination with ultrapulse CO 2 for the removal of black tattoo. Sixty patients with black tattoo were randomized into two groups viz., group A and group B. Group A was treated with QS Nd:YAG laser (1064 nm) alone, and group B received combination of ablative ultrapulse CO 2 followed by fixed-dose QS Nd:YAG laser (1064 nm), at 6-week interval for a maximum of 6 sittings. After each sitting, 3 independent physicians noted percentage of improvement that was evaluated using visual analogue scale (VAS) and grading system for tattoo ink lightening (TIL). Combination laser (group B) showed statistically significant improvement in mean VAS score in the last 2 noted visits as compared to 1st session (p tattoos, combination of ultrapulse CO 2 laser and QS Nd:YAG laser is superior to QS Nd:YAG laser alone.

  19. Tattoo removal in micropigs with low-energy pulses from a Q-switched Nd:YAG laser at 1064 nm (United States)

    Hu, Xin-Hua; Wooden, W. A.; Cariveau, Mickael J.; Fang, Qiyin; Bradfield, J. F.; Kalmus, Gerhard W.; Vore, S. J.; Sun, Y.


    Treatment of pigmented lesions in skin with visible or near- infrared nanosecond (ns) laser pulses often causes significant collateral tissue damage because the current approach uses pulses with energy of 300 mJ or larger. Additionally, this requires large Q-switched laser systems. To overcome these disadvantages, we have investigated a different approach in delivering ns laser pulses for cutaneous lesion treatment. Tattoo removal in an animal model with a focused laser beam from a Q-switched Nd:YAG laser has been investigated in two Yucatan micropigs tattooed with blue, black, green and red pigments. The tattoos were treated with a focused beam of 12-ns pulses at 1064 nm, with different depth under the skin surface, while the micropig was translated to achieve an effect of single pulse per ablation site in the skin. With the pulse energy reduced to a range from 38 to 63 mJ, we found that nearly complete clearance was achieved for blue and black tattoos while clearance of red and green tattoos was incomplete. Analysis of the skin appearance suggested that the pulse energy can be decreased to below 20 mJ which may lead to further reduction of the collateral tissue damage and improve the clearance of red and green tattoos.

  20. Effect of spot size and fluence on Q-switched alexandrite laser treatment for pigmentation in Asians: a randomized, double-blinded, split-face comparative trial. (United States)

    Wang, Chia-Chen; Chen, Chih-Kang


    Q-switched laser treatment for pigment disorders commonly leads to postinflammatory hyperpigmentation (PIH) in Asians. To evaluate the effect of spot size and fluence on Q-switched alexandrite laser (QSAL) treatment for pigmentation in Asians. Ten patients with freckles, 18 with lentigines, and 8 with acquired bilateral nevus of Ota-like macules (ABNOM) received 1 session of QSAL treatment for a 3-mm spot on one cheek and a 4-mm spot on the other cheek. The lowest fluences to achieve a visible biologic effect were chosen. The patients with freckles experienced the highest improvement rate (83-84%), followed by those with lentigines (52%) and ABNOM (35%). Similar efficacy was observed for both cheeks (p > 0.05). PIH developed in 10% (1/10), 44% (8/18), and 75% (6/8) of the patients with freckles, lentigines, and ABNOM, respectively. The severity of PIH was lower in the 4-mm spot with a lower fluence than in the 3-mm spot with a higher fluence in patients with lentigines (p = 0.03), but not in those with freckles or ABNOM. Using a larger spot to achieve the same biologic effect at a lower fluence is associated with equal efficacy and less-severe PIH in patients with lentigines.

  1. Computational model of dual q-switching and lasing processes of the pulsed Cr4+:YAG laser pumped by Nd-glass laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.


    A mathematical model describing the absorption and oscillation processes of intracavity Cr 4+ : YAG crystal pumped by Nd-glass laser has been developed, in order to describe the temporal behavior of laser-absorber system. The model has been assumed that the Cr 4+ ions excited to a higher level by excited state absorption, followed by relaxation directly to the upper laser level through fast channel, and indirectly through slow proposed intermediate channel at different lifetimes. The model offers simple kinetic mechanisms for pulsed solid state lasers and also the influence of the variations of the laser input parameters (pumping rate, maximum amplification coefficient and loss coefficient) on the output pulse characteristics of the passive Q-switched Nd-glass and pulsed Cr 4+ : YAG lasers. The model estimates the temporal behavior of the population densities of different levels and laser beam densities as well as predicts the nanosecond output laser pulses of passive Q-switched Nd-glass laser and pulsed Cr 4+ : YAG laser. The calculated results are in good agreement with the available experimental and theoretical data in the literature. (author)

  2. A Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser (United States)

    Wang, Y. P.; Dai, T. Y.; Wu, J.; Ju, Y. L.; Yao, B. Q.


    We report the acousto-optically Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser. In the continuous-wave operation of Ho:YAG laser, the maximum s-polarized output power of 3.2 W at 2090.3 nm was obtained under the absorbed pump power of 12.9 W by rotating the fast axis of quarter-wave plate to change the output transmission of laser cavity. The corresponding optical-to-optical conversion efficiency was 24.8% and the slope efficiency was 55.7%. When one of the corner cubes was rotated to 11.8° around vertical direction or 6.7° around horizontal direction, the laser could still operate stably. For the Q-switched operation, the pulse energy of Ho:YAG laser was 9.9 mJ with a pulse width of 53 ns at the repetition rate of 100 Hz, resulting in a peak power of 186.8 kW. The beam quality factor M2 of Ho:YAG laser was 1.3.

  3. CW and AO Q-switched operation of a dual-crystal Tm, Ho:GdVO4 laser pumped by two diodes

    International Nuclear Information System (INIS)

    Li, L J; Bai, Y F; Liu, Y W; He, Z L; Wang, J; Yao, B Q; Zhou, S; Xing, M N


    Continuous wave (CW) mode and acousto-optic (AO) Q-switched mode operation of a dual-crystal Tm, Ho:GdVO 4 laser is reported. The dual-crystal Tm, Ho:GdVO 4 laser with output wavelength of 2.05 μm was pumped by two laser diodes (LDs). The Tm, Ho:GdVO 4 crystals were cooled by liquid nitrogen and pumped by two fiber-coupled LDs with a center output wavelength of 801.0 nm. A 20.5 W output power was obtained at a 255 mm physical cavity length in CW mode operation, and a 19.6 W average power was obtained at a pulse repetition frequency (PRF) of 10 kHz with a 19 ns pulse duration. Also, the efficiency loss of the laser is not more than 4.4% from CW mode to Q-switch mode, and the M 2 factor, which is measured by the traveling knife-edge method, does not exceed 1.2. (paper)

  4. Diode-pumped continuous-wave and passively Q-switched 1066 nm Nd:GYNbO4 laser (United States)

    Ma, Yufei; Peng, Zhenfang; He, Ying; Li, Xudong; Yan, Renpeng; Yu, Xin; Zhang, Qingli; Ding, Shoujun; Sun, Dunlu


    A diode-pumped passively Q-switched 1066 nm laser with a novel Nd:Gd0.69Y0.3NbO4 mixed crystal was demonstrated for the first time to the best of our knowledge. In the continuous-wave (CW) operation, optimization selection of output couplers was carried out, and a maximum output power of 2.13 W was obtained when the plane mirror with transmission of 25% was chosen and the absorbed pump power was 10.5 W. The Cr4+:YAG passively Q-switched Nd:Gd0.69Y0.3NbO4 laser performance was investigated. At an absorbed pump power of 10.5 W, using Cr4+:YAG with initial transmission of 80%, the obtained minimum pulse width was 7.2 ns with the pulse repetition rate of 19 kHz. The single pulse energy and peak power were estimated to be 26.7 µJ and 3.7 kW, respectively.

  5. An All-Fiber Gas Raman Light Source Based on a Hydrogen-Filled Hollow-Core Photonic Crystal Fiber Pumped with a Q-Switched Fiber Laser

    International Nuclear Information System (INIS)

    Chen Xiao-Dong; Mao Qing-He; Sun Qing; Zhao Jia-Sheng; Li Pan; Feng Su-Juan


    A gas Raman light source based on a H 2 -filled hollow-core photonic-crystal-fiber cell with a Q-switched fiber laser followed by a fiber amplifier as the Raman pump source is demonstrated. The Stokes frequency-shift lasing line is observed at 1135.7 nm with the Q-switched pump pulses at 1064.7 nm. Our experimental results show that the generated Stokes pulse is much narrower than the pump pulse, and the generated Stokes pulse duration is increased with the single pulse energy for the same duration pump pulses. For the 125 ns pump pulses with a repetition rate of 5 kHz, the Raman threshold pump energy and the conversion efficiency at the Raman threshold are 2.13 μJ and 9.82%. Moreover, by choosing narrower pump pulses, the Raman threshold pump energy may be reduced and the conversion efficiency may be improved. (fundamental areas of phenomenology(including applications))

  6. Passively Q-switched of EDFL employing multi-walled carbon nanotubes with diameter less than 8 nm as saturable absorber

    Directory of Open Access Journals (Sweden)

    Zuikafly Siti Nur Fatin


    Full Text Available The paper demonstrates passively Q-switched erbium-doped fiber laser implementing multiwalled carbon nanotubes (MWCNTs based saturable absorber. The paper is the first to report the use of the MWCNTs with diameter less than 8 nm as typically, the diameter used is 10 to 20 nm. The MWCNTs is incorporated with water soluble host polymer, polyvinyl alcohol (PVA to produce a MWCNTs polymer composite thin film which is then sandwiched between two fiber connectors. The fabricated SA is employed in the laser experimental setup in ring cavity. The Q-switching regime started at threshold pump power of 103 mW and increasable to 215 mW. The stable pulse train from 41.6 kHz to 76.92 kHz with maximum average output power and pulse energy of 0.17 mW and 3.39 nJ are produced. The shortest pulse width of 1.9 μs is obtained in the proposed experimental work, making it the lowest pulse width ever reported using MWCNTs-based saturable absorber.

  7. Spectral and power characteristics of a 5% Tm : KLu(WO4)2 Nm-cut minislab laser passively Q-switched by a Cr2+ : ZnSe crystal (United States)

    Vatnik, S. M.; Vedin, I. A.; Kurbatov, P. F.; Smolina, E. A.; Pavlyuk, A. A.; Korostelin, Yu. V.; Skasyrsky, Ya. K.


    Laser characteristics of a 5%Tm : KLu(WO4)2 Nm-cut minislab laser passively Q-switched by a Cr2+ : ZnSe saturable absorber are presented. At a pump power of 21 W, the average laser power at a wavelength of 1.91 μm was 3.2 W (pulse duration 35 ns, pulse energy 0.3 mJ). The maximum slope efficiency of the laser in the Q-switched regime was 31%; the loss in power with respect to the cw regime did not exceed 17%. At pump powers above 15 W, the dependence of the output power in the Q-switched regime on the pump power considerably differed from linear, which was explained by the formation of a thermal lens in the saturable absorber volume. The experimental energies and durations of laser pulses well agree with the values calculated from rate equations.

  8. Electro-optic control of a PPLN-unpoled LiNbO3 boundary for low-voltage Q switching of an intracavity frequency-doubled Nd3+:YVO4 laser. (United States)

    Torregrosa, A J; Maestre, H; Fernández-Pousa, C R; Pereda, J A; Capmany, J


    We present a simple technique to integrate an electro-optic Q switch in a periodically poled bulk lithium niobate crystal bounded by two unpoled (monodomain) regions. The technique exploits the high sensitivity to low applied electric fields of the total internal reflection condition in the periodic poled-unpoled boundary for the small grazing incidence angles associated with the diffraction of a focused Gaussian beam that propagates in the periodically poled region with its axis parallel to the boundary. When the arrangement is placed intracavity to a 1064 nm diode-pumped Nd(3+):YVO(4) laser, it performs simultaneously as a Q switch and as a second-harmonic generator, with Q switching starting at applied voltages as low as 1 V over a 500 microm thickness and with no additional optical elements.

  9. Successful treatment of tattoo-induced pseudolymphoma with sequential ablative fractional resurfacing followed by Q-switched Nd: Yag 532 nm laser

    Directory of Open Access Journals (Sweden)

    Tan Siyun Lucinda


    Full Text Available Decorative tattooing has been linked with a range of complications, with pseudolymphoma being unusual and challenging to manage. We report a case of tattoo-induced pseudolymphoma, who failed treatment with potent topical and intralesional steroids. She responded well to sequential treatment with ablative fractional resurfacing (AFR followed by Q-Switched (QS Nd:YAG 532 nm laser. Interestingly, we managed to document the clearance of her tattoo pigments after laser treatments on histology and would like to highlight the use of special stains such as the Grocott′s Methenamine Silver (GMS stain as a useful method to assess the presence of tattoo pigment in cases where dense inflammatory infiltrates are present.

  10. The study of 670.7 nm red light generated by intracavity frequency doubling of a Q-switched Nd : YAlO3 laser

    International Nuclear Information System (INIS)

    Zhu Haiyong; Zhang Ge; Huang Chenghui; Wei Yong; Huang Lingxiong; Huang Yidong


    High-power 670.7 nm red light was obtained by intracavity frequency doubling of a Q-switched Nd : YAlO 3 (Nd : YAP) laser with a critical phase matching (θ = 85.9 0 , φ = 0 0 ) cut LBO. Experimental configurations using V-cavity and Z-cavity have been adopted for comparison. The highest output power of 19.7 W was achieved in the Z-cavity with optical-optical efficiency of 4%. Compared with the laser using an Nd : YAG crystal, the adoption of Nd : YAP simplified the laser system in the absence of a solid etalon and the Brewster plate. The output power stability of the red laser was investigated and the fluctuation was lower than 3% at the output power of 18 W an hour.

  11. Black phosphorus saturable absorber for a diode-pumped passively Q-switched Er:CaF2 mid-infrared laser (United States)

    Li, Chun; Liu, Jie; Guo, Zhinan; Zhang, Han; Ma, Weiwei; Wang, Jingya; Xu, Xiaodong; Su, Liangbi


    A multilayer black phosphorus, as a novel two dimensional saturable absorber, has superb saturable absorption properties for a Er:CaF2 solid-state pulse laser. The pulse laser is realized at mid-infrared region with the passively Q-switched technology by a diode-pumping. The high-quality black phosphorus saturable absorber is fabricated by liquid phase exfoliation method. The pulse laser generates the pulses operation with the pulse duration of 954.8 ns, the repetition rate of 41.93 kHz, the pulse energy of 4.25 μJ and the peak power of 4.45 W. Our work demonstrates that black phosphorus could be used as a kind of efficient mid-infrared region optical absorber for ultrafast photonics.

  12. Cw and Q-switched Nd:NaLa(MoO4)2 laser noncritical to the temperature drift of the diode pump laser wavelength

    International Nuclear Information System (INIS)

    Ushakov, S N; Lis, Denis A; Subbotin, Kirill A; Romanyuk, V A; Shestakov, A V; Ryabochkina, P A; Shestakova, I A; Zharikov, Evgeny V


    Lasing in Nd:NaLa(MoO 4 ) 2 crystals is obtained without stabilisation of the diode pump wavelength. A dependence of the cw laser power (at a wavelength of 1059 nm) on the pump diode temperature is found within a range of 10-458C. It is shown that the variations in the diode temperature within this region change the lasing efficiency no more than by 30%. In the passive Q-switching regime, the experiments were performed under both pulsed and cw pumping. Upon pulsed pumping, the laser energy was 16 μJ at the output pulse duration of 11 ns. The laser wavelength was 1059 nm, as well as in the case of cw operation. Upon cw pumping with a power of 1.5 W, laser pulses were obtained with an energy of 15 μJ. (lasers)

  13. Continuous-wave and acousto-optically Q-switched 1066 nm laser performance of a novel Nd:GdTaO4 crystal (United States)

    Ma, Yufei; He, Ying; Peng, Zhenfang; Sun, Haiyue; Peng, Fang; Yan, Renpeng; Li, Xudong; Yu, Xin; Zhang, Qingli; Ding, Shoujun


    A diode-pumped acousto-optically (AO) Q-switched 1066 nm laser with a novel Nd:GdTaO4 crystal was demonstrated for the first time to the best of our knowledge. The optimization selection of output coupler was carried out in the continuous-wave (CW) operation. After that the pulsed Nd:GdTaO4 laser performances using different modulation repetition rates of 10 kHz and 20 kHz were investigated. At an absorbed pump power of 10 W and repetition rates of 10 kHz, the obtained minimum pulse width was 28 ns and the maximum peak power was 5.4 kW.

  14. Generation of nanosecond laser pulses at a 2.2-MHz repetition rate by a cw diode-pumped passively Q-switched Nd3+:YVO4 laser

    International Nuclear Information System (INIS)

    Nghia, Nguyen T; Hao, Nguyen V; Orlovich, Valentin A; Hung, Nguyen D


    We report a new configuration of a high-repetition rate nanosecond laser based on a semiconductor saturable absorber mirror (SESAM). The SESAM is conventional technical solution for passive mode-locking at 1064 nm and simultaneously used as a highly reflecting mirror and a saturable absorber in a high-Q and short cavity of a cw diode-end-pumped a-cut Nd 3+ :YVO 4 laser. Two laser beams are coupled out from the cavity using an intracavity low-reflection thin splitter. The laser characteristics are investigated as functions of pump and resonator parameters. Using a 1.8-W cw pump laser diode at 808 nm, the passively Q-switched SESAMbased laser generates 22-ns pulses with an average power of 275 mW at a pulse repetition rate of 2250 kHz.

  15. Successful Treatment of Tattoo-Induced Pseudolymphoma with Sequential Ablative Fractional Resurfacing Followed by Q-Switched Nd: YAG 532 nm Laser (United States)

    Lucinda, Tan Siyun; Hazel, Oon Hwee Boon; Joyce, Lee Siong Siong; Hon, Chua Sze


    Decorative tattooing has been linked with a range of complications, with pseudolymphoma being unusual and challenging to manage. We report a case of tattoo-induced pseudolymphoma, who failed treatment with potent topical and intralesional steroids. She responded well to sequential treatment with ablative fractional resurfacing (AFR) followed by Q-Switched (QS) Nd:YAG 532 nm laser. Interestingly, we managed to document the clearance of her tattoo pigments after laser treatments on histology and would like to highlight the use of special stains such as the Grocott's Methenamine Silver (GMS) stain as a useful method to assess the presence of tattoo pigment in cases where dense inflammatory infiltrates are present. PMID:24470721

  16. Mass removal modes in the laser ablation of silicon by a Q-switched diode-pumped solid-state laser (DPSSL)

    International Nuclear Information System (INIS)

    Lim, Daniel J; Ki, Hyungson; Mazumder, Jyoti


    A fundamental study on the Q-switched diode-pumped solid-state laser interaction with silicon was performed both experimentally and numerically. Single pulse drilling experiments were conducted on N-type silicon wafers by varying the laser intensity from 10 8 -10 9 W cm -2 to investigate how the mass removal mechanism changes depending on the laser intensity. Hole width and depth were measured and surface morphology was studied using scanning electron microscopy. For the numerical model study, Ki et al's self-consistent continuous-wave laser drilling model (2001 J. Phys. D: Appl. Phys. 34 364-72) was modified to treat the solidification phenomenon between successive laser pulses. The model has the capabilities of simulating major interaction physics, such as melt flow, heat transfer, evaporation, homogeneous boiling, multiple reflections and surface evolution. This study presents some interesting results on how the mass removal mode changes as the laser intensity increases

  17. Observation of Q-switching and mode-locking in two-section InAs/InP (100) quantum dot lasers around 1.55 mum. (United States)

    Heck, Martijn J R; Bente, Erwin A J M; Smalbrugge, Barry; Oei, Yok-Siang; Smit, Meint K; Anantathanasarn, Sanguan; Nötzel, Richard


    First observation of passive mode-locking in two-section quantum-dot lasers operating at wavelengths around 1.55 mum is reported. Pulse generation at 4.6 GHz from a 9 mm long device is verified by background-free autocorrelation, RF-spectra and real-time oscilloscope traces. The output pulses are stretched in time and heavily up-chirped with a value of 20 ps/nm, contrary to what is normally observed in passively mode-locked semiconductor lasers. The complete output spectrum is shown to be coherent over 10 nm. From a 7 mm long device Q-switching is observed over a large operating regime. The lasers have been realized using a fabrication technology that is compatible with further photonic integration. This makes the laser a promising candidate for e.g. a mode-comb generator in a complex photonic chip.

  18. MoTe2 saturable absorber for passively Q-switched Ho,Pr:LiLuF4 laser at ∼3 μm (United States)

    Yan, Zhengyu; Li, Tao; Zhao, Shengzhi; Yang, Kejian; Li, Dechun; Li, Guiqiu; Zhang, Shuaiyi; Gao, Zijing


    Multilayer molybdenum ditelluride (MoTe2) nanosheets were prepared by liquid-phase exfoliation (LPE) method. A YAG-based MoTe2 saturable absorption (SA) was consequently fabricated. The MoTe2-SA was employed in a passively Q-switched Ho,Pr:LiLuF4 laser at 2.95 μm. Under the absorbed pump power of 3.8 W, an average output power of 90 mW was achieved. The shortest pulse duration of 670 ns was generated with an output power of 73 mW and a repetition rate of 76.46 kHz, corresponding to a pulse energy of 0.95 μJ.

  19. Passive Q-switching of femtosecond-laser-written Tm:KLu(WO4)2 waveguide lasers by graphene and MoS2 saturable absorbers (United States)

    Kifle, Esrom; Mateos, Xavier; Vázquez de Aldana, Javier Rodríguez; Ródenas, Airan; Loiko, Pavel; Zakharov, Viktor; Veniaminov, Andrey; Yu, Haohai; Zhang, Huaijin; Chen, Yanxue; Aguiló, Magdalena; Díaz, Francesc; Griebner, Uwe; Petrov, Valentin


    A buried depressed-index channel waveguide with a circular cladding and a core diameter of 40 μm is fabricated in a bulk monoclinic 3 at.% Tm:KLu(WO4)2 crystal by femtosecond direct laser writing. In the continuous-wave regime, the Tm waveguide laser generates 210 mW at 1849.6 nm with a slope efficiency η of 40.8%. Passively Q-switched operation is achieved by inserting transmission-type 2D saturable absorbers (SAs) based on few-layer graphene and MoS2. Using the graphene-SA, a maximum average output power of 25 mW is generated at 1844.8 nm. The pulse characteristics (duration/energy) are 88 ns/18 nJ at a repetition rate of 1.39 MHz.

  20. Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo; Chen, Rongzhang; Nelsen, Bryan; Chen, Kevin, E-mail: [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Liu, Lei; Huang, Xi; Lu, Yongfeng [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)


    This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications.

  1. Low-threshold, nanosecond, high-repetition-rate vortex pulses with controllable helicity generated in Cr,Nd:YAG self-Q-switched microchip laser (United States)

    He, Hong-Sen; Chen, Zhen; Li, Hong-Bin; Dong, Jun


    A high repetition rate, nanosecond, pulsed optical vortex beam has been generated in a Cr,Nd:YAG self-Q-switched microchip laser pumped by the annular-beam formed with a hollow focus lens. The lasing threshold for vortex pulses is 0.9 W. A pulse width of 6.5 ns and a repetition rate of over 330 kHz have been achieved. The average output power of 1 W and the slope efficiency of 46.6% have been obtained. The helicity of the optical vortices has been controlled by adjusting the tilted angle between Cr,Nd:YAG crystal and output coupler. The work provides a new method for developing pulsed optical vortices for potential applications on quantum communication and optical trapping.

  2. Broadband generation by multiple four-wave mixing process due to ASE Q-switching in high-power double-clad ytterbium-doped fiber amplifier (United States)

    Chowdhury, Sourav D.; Shekhar, Nishant; Saha, Maitreyee; Sen, Ranjan; Pal, Mrinmay


    Broadband output from 1060nm to 1700nm and cascaded four-wave mixing generated red light pulsing is observed in a fiber amplifier set up consisting of a 5.5m double clad, double D shaped Ytterbium doped fiber, a single clad passive fiber for excess pump absorption and a splitter, both with and without a CW seed. Self-pulsing occurs from ASE due to passive Q-switching by saturable absorption effect of the active fiber and also depends on splice loss. The pulses generate broadband output by multiple four-wave mixing process with maximum broadening efficiency near 1300nm which is the zero dispersion wavelength for silica fiber. Pulses traveling both in forward and backward direction have enough peak power and energy to damage splice points and fiber components. When seeded the self-pulsing and broadband generation is often suppressed but again generate at increased pump powers.

  3. Characterisation of the light pulses of a cavity dumped dye laser pumped by a cw mode-locked and q-switched Nd:YAG laser

    International Nuclear Information System (INIS)

    Geist, P.; Heisel, F.; Martz, A.; Miehe, J.A.; Miller, R.J.D.


    The frequency doubled pulses (of 532 nm) obtained, with the help of a KTP crystal, from those delivered by either a continuous wave mode-locked (100 MHz) or mode-locked Q-switched (0-1 KHz) Nd: YAG laser, are analyzed by means of a streak camera, operating in synchroscan or triggered mode. In the step-by-step measurements the pulse stability, concerning form and amplitude, is shown. In addition, measurements effectuated with synchronously pumped and cavity dumped dye laser (Rhodamine 6G), controlled by a Pockels cell, allows the obtention of stable and reproducible single pulses of 30 ps duration, 10 μJ energy and 500Hz frequency [fr

  4. Potential role of S100A8 in skin rejuvenation with the 1064-nm Q-switched Nd:YAG laser. (United States)

    Qin, Yan; Qin, Xiaofeng; Xu, Peng; Zhi, Yuanting; Xia, Weili; Dang, Yongyan; Gu, Jun; Ye, Xiyun


    The 1064-nm Q-switched Nd:YAG laser is demonstrated to be effective for non-ablative skin rejuvenation, but the molecular mechanism by which dermis responses to laser-induced damage and initiates skin remodeling is still unclear. HaCaT cells and 3T3 skin fibroblasts were irradiated with the 1064-nm Q-switched Nd:YAG laser at the different doses. Then, cells were collected and lysed for PCR and Western blot analysis. Cell viability was detected by Cell Counting Kit-8 (CCK-8) before and after laser irradiation. The expressions of S100A8, advanced glycosylation end product-specific receptor (RAGE) and inflammatory cytokines in two cell lines were markedly upregulated after laser treatments. The PCR, Western blot, and ELISA analysis showed the significant increase of type I and III procollagen in the 3T3 cells treated with the 1064-nm laser. Interestingly, si S100A8 effectively inhibited the expression of cytokines and collagen, while S100A8 treatments significantly increased them. P-p38 and p-p65 levels were also elevated after the 1064-nm laser irradiation, which is positively related with S100A8. Cell viability and reactive oxygen species (ROS) levels were not changed, while the content of superoxidase dismutase (SOD) in two cells was increased after laser irradiation. Our results demonstrated that the overexpression of S100A8 induced by the 1064-nm laser irradiation triggered inflammatory reactions in skin cells. The inflammatory microenvironment and improvement of skin antioxidant capacity contribute to new collagen synthesis in the skin cells. Thus, S100A8 was required for laser-induced new collagen synthesis in skin cells. p38/MAPK and NF-κB signal pathways were involved in S100A8-mediated inflammatory reactions in response to laser irradiation.

  5. Combined therapy using Q-switched ruby laser and bleaching treatment with tretinoin and hydroquinone for periorbital skin hyperpigmentation in Asians. (United States)

    Momosawa, Akira; Kurita, Masakazu; Ozaki, Mine; Miyamoto, Shinpei; Kobayashi, Yo; Ban, Izumi; Harii, Kiyonori


    Periorbital skin hyperpigmentation, so-called dark circles, is of major concern for many people. However, only a few reports refer to the morbidity and treatment, and as far as the authors know, there are no reports of the condition in Asians. A total of 18 Japanese patients underwent combined therapy using Q-switched ruby laser to eliminate dermal pigmentation following topical bleaching treatment with tretinoin aqueous gel and hydroquinone ointment performed initially (6 weeks) to reduce epidermal melanin. Both steps were repeated two to four times until physical clearance of the pigmentation was confirmed and patient satisfaction was achieved. Skin biopsy was performed at baseline in each patient and at the end of treatment in three patients, all with informed consent. Clinical and histologic appearances of periorbital hyperpigmentation were evaluated and rated as excellent, good, fair, poor, or default. Seven of 18 patients (38.9 percent) showed excellent clearing after treatment and eight (44.4 percent) were rated good. Only one (5.6 percent) was rated fair and none was rated poor. Postinflammatory hyperpigmentation was observed in only two patients (11.1 percent). Histologic examination showed obvious epidermal hyperpigmentation in 10 specimens. Dermal pigmentation was observed in all specimens but was not considered to be melanocytosis. Remarkable reduction of dermal pigmentation was observed in the biopsy specimens of three patients after treatment. The new treatment protocol combining Q-switched ruby laser and topical bleaching treatment using tretinoin and hydroquinone is considered effective for improvement of periorbital skin hyperpigmentation, with a low incidence of postinflammatory hyperpigmentation.

  6. Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos. (United States)

    Lakshmi, Chembolli; Krishnaswamy, Gayathri


    Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm(2). The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals.

  7. Rapid, high-fluence multi-pass q-switched laser treatment of tattoos with a transparent perfluorodecalin-infused patch: A pilot study. (United States)

    Biesman, Brian S; O'Neil, Michael P; Costner, Cara


    Perfluorodecalin (PFD) has previously been shown to rapidly dissipate the opaque, white micro-bubble layer formed after exposure of tattoos to Q-switched lasers [1]. The current pilot study was conducted to qualitatively determine if the use of a transparent PFD-infused silicone patch would result in more rapid clearance of tattoos than conventional through-air techniques. Black or dark blue tattoos were divided into two halves in a single-site IRB-approved study with 17 subjects with Fitzpatrick skin types I-III. One half of each tattoo served as its own control and was treated with one pass of a standard Q-switched Alexandrite laser (755 nm). The other half of the tattoo was treated directly through a transparent perfluorodecalin (PFD) infused patch (ON Light Sciences, Dublin, CA). The rapid whitening reduction effect of the Patch routinely allowed three to four laser passes in a total of approximately 5 minutes. Both sides were treated at highest tolerated fluence, but the optical clearing, index-matching, and epidermal protection properties of the PFD Patch allowed significantly higher fluence compared to the control side. Standard photographs were taken at baseline, immediately prior to treatment with the PFD Patch in place, and finally before and after each treatment session. Treatments were administered at 4- to 6-week intervals. In a majority of subjects (11 of 17), tattoos treated through a transparent PFD-infused patch showed more rapid tattoo clearance with higher patient and clinician satisfaction than conventional treatment. In no case did the control side fade faster than the PFD Patch side. No unanticipated adverse events were observed. Rapid multi-pass treatment of tattoos with highest tolerated fluence facilitated by a transparent PFD-infused patch clears tattoos more rapidly than conventional methods. © 2015 Wiley Periodicals, Inc.

  8. Enlarged pores treated with a combination of Q-switched and micropulsed 1064 nm Nd:YAG laser with and without topical carbon suspension: A simultaneous split-face trial


    Chung, HJ; Goo, BC; Lee, HJ; Roh, MR; Chung, KY


    Background and aims: Enlarged facial pores remain one of the major cosmetic concerns among Asian females. This study attempted to assess and compare the efficacy of a combination of the Q-switched and quasi long-pulsed (micropulsed) Nd:YAG laser to reduce the size of the enlarged pores with and without an exogenous photoenhancer.

  9. Effect of laser beam conditioning on fabrication of clean micro-channel on stainless steel 316L using second harmonic of Q-switched Nd:YAG laser (United States)

    Singh, Sanasam Sunderlal; Baruah, Prahlad Kr; Khare, Alika; Joshi, Shrikrishna N.


    Laser micromachining of metals for fabrication of micro-channels generate ridge formation along the edges accompanied by ripples along the channel bed. The ridge formation is due to the formation of interference pattern formed by back reflections from the beam splitter and other optical components involved before focusing on the work piece. This problem can be curtailed by using a suitable aperture or Iris diaphragm so as to cut the unwanted portion of the laser beam before illuminating the sample. This paper reports an experimental investigation on minimizing this problem by conditioning the laser beam using an Iris diaphragm and using optimum process parameters. In this work, systematic experiments have been carried out using the second harmonic of a Q-switched Nd:YAG laser to fabricate micro-channels. Initial experiments revealed that formation of ridges along the sides of micro-channel can easily be minimized with the help of Iris diaphragm. Further it is noted that a clean micro-channel of depth 43.39 μm, width up to 64.49 μm and of good surface quality with average surface roughness (Ra) value of 370 nm can be machined on stainless steel (SS) 316L by employing optimum process condition: laser beam energy of 30 mJ/pulse, 11 number of laser scans and scan speed of 169.54 μm/s with an opening of 4 mm diameter of Iris diaphragm in the path of the laser beam.

  10. Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers. (United States)

    Ahn, K J; Kim, B J; Cho, S B


    Laser therapy is the treatment of choice in tattoo removal. However, the precise mechanisms of laser-tattoo pigment interactions remain to be evaluated. We evaluated the geometric patterns of laser-tattoo pigment particle interactions using a tattoo pigment-embedded tissue-mimicking (TM) phantom. A Q-switched (QS) neodymium-doped yttrium aluminum garnet laser was used at settings of 532-, 660-, and 1064-nm wavelengths, single-pulse and quick pulse-to-pulse treatment modes, and spot sizes of 4 and 7 mm. Most of the laser-tattoo interactions in the experimental conditions formed cocoon-shaped or oval photothermal and photoacoustic injury zones, which contained fragmented tattoo particles in various sizes depending on the conditions. In addition, a long-pulsed 755-nm alexandrite laser was used at a spot size of 6 mm and pulse widths of 3, 5, and 10 ms. The finer granular pattern of tattoo destruction was observed in TM phantoms treated with 3- and 5-ms pulse durations compared to those treated with a 10-ms pulse. We outlined various patterns of laser-tattoo pigment interactions in a tattoo-embedded TM phantom to predict macroscopic tattoo and surrounding tissue reactions after laser treatment for tattoo removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Continuous wave and AO Q-switch operation Tm,Ho:YAP laser pumped by a laser diode of 798 nm

    International Nuclear Information System (INIS)

    Li, L J; Yao, B Q; Song, C W; Wang, Y Z; Wang, Z G


    Continuous wave (CW) and acousto-optical (AO) Q-switch operation of Tm (5 at.%), Ho (0.3 at.%):YAP laser at 2.13 μm wavelength were reported in this paper. The Tm,Ho:YAP crystal was cooled by liquid nitrogen and double-end-pumped by a 14.2 W fiber-coupled laser diode at 798 nm. Different resonator lengths and output couplers for the pump power were tried. A maximum conversion efficiency of 31.3% and a maximum slope efficiency of 35.2% were acquired with CW output power of 4.45 W. Average power of 4.21 W was obtained at pulse repetition frequency (PRF) of 15 kHz, corresponding to an optical-to-optical conversion efficiency of 29.6% and a slope efficiency of 32.4%. The energy per pulse of 2.3 mJ in 64 ns was achieved at 1.5 kHz with the peak power of 35.8 kW

  12. Sub-nanosecond periodically poled lithium niobate optical parametric generator and amplifier pumped by an actively Q-switched diode-pumped Nd:YAG microlaser (United States)

    Liu, L.; Wang, H. Y.; Ning, Y.; Shen, C.; Si, L.; Yang, Y.; Bao, Q. L.; Ren, G.


    A sub-nanosecond seeded optical parametric generator (OPG) based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal is presented. Pumped by an actively Q-switched diode-pumped 1 kHz, 1064 nm, Nd:YAG microlaser and seeded with a low power distributed feedback (DFB) diode continuous-wave (CW) laser, the OPG generated an output energy of 41.4 µJ and 681 ps pulse duration for the signal at 1652.4 nm, achieving a quantum conversion efficiency of 61.2% and a slope efficiency of 41.8%. Signal tuning was achieved from 1651.0 to 1652.4 nm by tuning the seed-laser current. The FWHM of the signal spectrum was approximately from 35 nm to 0.5 nm by injection seed laser. The SHG doubled the frequency of OPG signal to produce a output energy of 12 µJ with the energy conversion efficiency of 29.0% and tunanble wavelength near 826 nm.

  13. The influence of the Q-switched and free-running Er:YAG laser beam characteristics on the ablation of root canal dentine

    International Nuclear Information System (INIS)

    Papagiakoumou, Eirini; Papadopoulos, Dimitrios N.; Khabbaz, Marouan G.; Makropoulou, Mersini I.; Serafetinides, Alexander A.


    Laser based dental treatment is attractive to many researchers. Lasers in the 3 μm region, as the Er:YAG, are suitable especially for endodontic applications. In this study a pulsed free-running and Q-switched laser was used for the ablation experiments of root canal dentine. The laser beam was either directly focused on the dental tissue or delivered to it through an infrared fiber. For different spatial beam distributions, energies, number of pulses and both laser operations the quality characteristics (crater's shape formation, ablation efficiency and surface characteristics modification) were evaluated using scanning electron microscopy (SEM). The craters produced, generally, reflect the relevant beam profile. Inhomogeneous spatial beam profiles and short pulse duration result in cracks formation and lower tissue removal efficiency, while longer pulse durations cause hard dentine fusion. Any beam profile modification, due to laser characteristics variations and the specific delivering system properties, is directly reflected in the ablation crater shape and the tissue removal efficiency. Therefore, the laser parameters, as fluence, pulse repetition rate and number of pulses, have to be carefully adjusted in relation to the desirable result

  14. Efficient continuous-wave, broadly tunable and passive Q-switching lasers based on a Tm3+:CaF2 crystal (United States)

    Liu, Jingjing; Zhang, Cheng; Zu, Yuqian; Fan, Xiuwei; Liu, Jie; Guo, Xinsheng; Qian, Xiaobo; Su, Liangbi


    Laser operations in the continuous-wave as well as in the pulsed regime of a 4 at.% Tm3+:CaF2 crystal are reported. For the continuous-wave operation, a maximum average output power of 1.15 W was achieved, and the corresponding slope efficiency was more than 64%. A continuous tuning range of about 160 nm from 1877-2036 nm was achieved using a birefringent filter. Using Argentum nanorods as a saturable absorber, the significant pulsed operation of a passively Q-switched Tm3+:CaF2 laser was observed at 1935.4 nm for the first time, to the best of our knowledge. A maximum output power of 385 mW with 41.4 µJ pulse energy was obtained under an absorbed pump power of 2.04 W. The present results indicate that the Tm3+:CaF2 lasers could be promising laser sources to operate in the eye-safe spectral region.

  15. Graphene-PVA saturable absorber for generation of a wavelength-tunable passively Q-switched thulium-doped fiber laser in 2.0 µm (United States)

    Ahmad, H.; Samion, M. Z.; Sharbirin, A. S.; Norizan, S. F.; Aidit, S. N.; Ismail, M. F.


    Graphene, a 2D material, has been used for generation of pulse lasers due to the presence of its various fascinating optical properties compared to other materials. Hence in this paper, we report the first demonstration of a thulium doped fiber laser with a wavelength-tunable, passive Q-switched output using a graphene-polyvinyl-alcohol composite film for operation in the 2.0 µm region. The proposed laser has a wavelength-tunable output spanning from 1932.0 nm to 1946.0 nm, giving a total tuning range of 14.0 nm. The generated pulse has a maximum repetition rate and average output power of 36.29 kHz and 0.394 mW at the maximum pump power of 130.87 mW, as well as a pulse width of 6.8 µs at this pump power. The generated pulses have a stable output, having a signal-to-noise ratio of 31.75 dB, and the laser output is stable when tested over a period of 60 min. The proposed laser would have multiple applications for operation near the 2.0 micron region, especially for bio-medical applications and range-finding.

  16. LD-pumped actively Q-switched c-cut Nd:GdVO4 self-Raman laser operating at 1166 and 1176 nm (United States)

    Sun, Xinzhi; Zhang, Xihe; Li, Shutao; Dong, Yuan


    A laser diode pumped actively Q-switched c-cut Nd:GdVO4 self-Raman laser is experimentally investigated. Simultaneous pulse outputs at 1166 nm and 1176 nm corresponding to the Raman shifts of 807 and 882 cm-1 are acquired. At the pulse repetition frequency (PRF) of 20 kHz, the maximum output power is 103 mW at 1166 nm with the incident pump power of 2.31 W, while 1176 nm output power reaches 530 mW with the incident pump power of 4.11 W. The maximum output power of Raman laser is 570 mW with the incident pump power of 4.11 W and the PRF of 30 kHz. With the incident pump power of 3.67 W and the PRF of 30 kHz, the highest diode-to-Stokes optical conversion efficiency of 14.9% is obtained with the corresponding average output power of 547 mW.

  17. A Q-switched Ho:YAG laser assisted nanosecond time-resolved T-jump transient mid-IR absorbance spectroscopy with high sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Deyong; Li, Yunliang; Li, Hao; Weng, Yuxiang, E-mail: [Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Xianyou [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, Qingxu [School of Physics and Optoelectronic Technology, Dalian University of Technology, No. 2, Linggong Road, Dalian 116023 (China)


    Knowledge of dynamical structure of protein is an important clue to understand its biological function in vivo. Temperature-jump (T-jump) time-resolved transient mid-IR absorbance spectroscopy is a powerful tool in elucidating the protein dynamical structures and the folding/unfolding kinetics of proteins in solution. A home-built setup of T-jump time-resolved transient mid-IR absorbance spectroscopy with high sensitivity is developed, which is composed of a Q-switched Cr, Tm, Ho:YAG laser with an output wavelength at 2.09 μm as the T-jump heating source, and a continuous working CO laser tunable from 1580 to 1980 cm{sup −1} as the IR probe. The results demonstrate that this system has a sensitivity of 1 × 10{sup −4} ΔOD for a single wavelength detection, and 2 × 10{sup −4} ΔOD for spectral detection in amide I′ region, as well as a temporal resolution of 20 ns. Moreover, the data quality coming from the CO laser is comparable to the one using the commercial quantum cascade laser.

  18. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince–Gaussian modes for optical trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jun Dong; Yu He; Xiao Zhou; Shengchuang Bai [Department of Electronics Engineering, School of Information Science and Engineering, Xiamen, 361005 (China)


    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping. (control of laser radiation parameters)

  19. Switching between the mode-locking and Q-switching modes in two-section QW lasers upon a change in the absorber properties due to the Stark effect

    Energy Technology Data Exchange (ETDEWEB)

    Gadzhiyev, I. M., E-mail:; Buyalo, M. S. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Gubenko, A. E. [Innolume GmbH (Germany); Egorov, A. Yu.; Usikova, A. A.; Il’inskaya, N. D.; Lyutetskiy, A. V.; Zadiranov, Yu. M.; Portnoi, E. L. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)


    The passive Q-switching and mode-locking modes are implemented in two-section lasers with three quantum wells. It is demonstrated that raising the reverse bias on the absorbing section changes its spectral and dynamic properties and, accordingly, leads to a change from the Q-switching mode to mode-locking. The pulse-repetition frequency in the mode-locking mode is 75 GHz, with the product of the pulse duration by the spectrum bandwidth being 0.49, which is close to the theoretical limit. It is shown that, in structures with three quantum wells, strong absorption at the lasing wavelength gives rise to a photocurrent across a section of the saturable absorber, which is sufficient for compensation of the applied bias.

  20. Switching between the mode-locking and Q-switching modes in two-section QW lasers upon a change in the absorber properties due to the Stark effect

    International Nuclear Information System (INIS)

    Gadzhiyev, I. M.; Buyalo, M. S.; Gubenko, A. E.; Egorov, A. Yu.; Usikova, A. A.; Il’inskaya, N. D.; Lyutetskiy, A. V.; Zadiranov, Yu. M.; Portnoi, E. L.


    The passive Q-switching and mode-locking modes are implemented in two-section lasers with three quantum wells. It is demonstrated that raising the reverse bias on the absorbing section changes its spectral and dynamic properties and, accordingly, leads to a change from the Q-switching mode to mode-locking. The pulse-repetition frequency in the mode-locking mode is 75 GHz, with the product of the pulse duration by the spectrum bandwidth being 0.49, which is close to the theoretical limit. It is shown that, in structures with three quantum wells, strong absorption at the lasing wavelength gives rise to a photocurrent across a section of the saturable absorber, which is sufficient for compensation of the applied bias.

  1. Treatment of melasma with low fluence, large spot size, 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the treatment of melasma in Fitzpatrick skin types II-IV. (United States)

    Brown, Alia S; Hussain, Mussarat; Goldberg, David J


    Melasma is a common condition affecting over six million American women. Treatment of dermal or combined melasma is difficult and does not respond well to conventional topical therapies. Various light sources have been used recently in the treatment of melasma including fractionated ablative and non-ablative lasers as well as intense pulse light. We report the use of low fluence, large spot size Q-switched, Nd:Yag laser for the treatment of melasma in skin types II-IV.

  2. Study on the pathogenesis of transient intraocular pressure after laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser

    Directory of Open Access Journals (Sweden)

    Zhi-Juan Pei


    Full Text Available AIM: To study the pathogenesis of transient intraocular pressure(IOPafter laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser. METHODS: Totally 42 healthy rabbits(84 eyesprovided by the Animal Experimental Center of our hospital were selected, including 18 female rabbits, 24 male rabbits, average weight 2.24±0.31kg, and they were randomly divided into 6 groups, 7 rats in each group(14 eyes. We observed the change of intraocular pressure after laser iridectomy surgery at 20min, 2, 6, 18, 24h and the nitric oxide(NO, malondialdehyde(MDA, superoxide dismutase(SOD, 6-keto-prostaglandin(6-keto-PGF1αand nitric oxide synthase(NOScontent in aqueous. RESULTS: There was no significant difference in intraocular pressure, NO, NOS, SOD, MAD and 6-keto- PGF1α before operation(P>0.05. The intraocular pressure increased after operation, and the difference was statistically significant(PP>0.05. The levels of NO, NOS and SOD in the aqueous humor of the two groups decreased 20min, 2 and 6h after the operation(PP>0.05. The levels of MDA and 6-keto-prostaglandin in the aqueous humor increased after the operation, and the difference was statistically significant at 20min, 2 and 6h after operation(PP>0.05.CONCLUSION: The increase of transient intraocular pressure after laser iridectomy may relate to the increase of malondialdehyde, 6-keto-prostaglandin content and the decrease of superoxide dismutase and nitric oxide in the aqueous humor after operation.

  3. Long-term evaluation of ink clearance in tattoos with different color intensity using the 1064-nm Q-switched Nd:YAG laser. (United States)

    Mankowska, Agata; Kasprzak, Wojciech; Adamski, Zygmunt


    The aim of the study was to evaluate the efficacy of tattoo removal treatments using the 1064-nm Q-switched (QS) Nd:YAG laser. Today, QS lasers appear to be the most common, effective, and safest methods to treat unwanted markings. A total of 64 patients with 75 unwanted tattoos were enrolled in the study. Tattoo clearance was evaluated according to the color intensity - concentration of pigment: group I (34) - black; group II (41) - gray. Consideration included methods of tattooing and tattoo techniques. In group I, after the first treatment session the median of clearance was 30% (10-50%), while in group II, the median was 50% (40-70%). After the second treatment session, median in group I increased to 40% (30-50%). Median of group II increased to 70% (50-80%). The highest number of treatment in group I was 7. After that, the median grew to 75%, while the highest amount of treatment in group II was 5 and a median of 90% was achieved. Effects were dependent upon the amount of ink deposited in the tissue. Old amateur tattoos and tattoos containing small quantities of ink (technique: shading and lines) demonstrated the quickest and the most efficacious results. Tattoos with large quantities of ink, obtained by filling, required the greatest number of treatment sessions. The final outcome in tattoo clearing can only be assessed following treatment completion, which may in some cases take 2-3 years. Presumably, in some cases, complete clearance is impossible. © 2015 Wiley Periodicals, Inc.

  4. Enlarged pores treated with a combination of Q-switched and micropulsed 1064 nm Nd:YAG laser with and without topical carbon suspension: A simultaneous split-face trial. (United States)

    Chung, Hj; Goo, Bc; Lee, Hj; Roh, Mr; Chung, Ky


    Enlarged facial pores remain one of the major cosmetic concerns among Asian females. This study attempted to assess and compare the efficacy of a combination of the Q-switched and quasi long-pulsed (micropulsed) Nd:YAG laser to reduce the size of the enlarged pores with and without an exogenous photoenhancer. In twenty five female subjects mean age 34.04 yr and skin type II-IV, a carbon lotion as a photoenhancer was applied on one side of the face (Method 1) and the other side was used as the control (Method 2). The entire face was then treated with a single pass of the 1064 nm Nd:YAG laser in the micropulsed mode, pulse fluence and width of 2.3 J/cm(2) and 300 µsec, respectively. Multiple passes were then delivered in the Q-switched mode (2.5 J/cm(2) and 5 nsec). Three weeks after the final treatment, 75% of the subjects showed improvement with method 1 whereas 67% showed improvement with method 2. No adverse side effects were reported with either method. Although histological confirmation was not performed, we were able to prove both subjectively and objectively that the use of the combination of the micropulsed and Q-switched modes of the Nd:YAG laser was useful in reducing pore size, and that the photoenhancer improved the efficacy.

  5. Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.


    The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

  6. Treatment of resistant tattoos using a new generation Q-switched Nd:YAG laser: influence of beam profile and spot size on clearance success. (United States)

    Karsai, Syrus; Pfirrmann, Gudrun; Hammes, Stefan; Raulin, Christian


    Multiple treatments of resistant tattoos often result in fibrosis and visible textural changes that lessen response to subsequent treatments. The aim of this study is to evaluate the influence of beam profile and spot size on clearance rates and side effects in the setting of resistant tattoos. Thirty-six professional, black tattoos (32 patients) were treated unsuccessfully with a Q-switched Nd:YAG laser (MedLite C3, HoyaConBio Inc., Fremont, CA). Because of therapy resistance all tattoos were re-treated using a new generation Nd:YAG laser (MedLite C6, HoyaConBio Inc.). Maximum energy fluence (E (max)), mean energy fluence, mean spot size, level of clearance, side effects and beam profile (irradiance distribution) of both laser systems were assessed and evaluated in a retrospective study. All tattoos were previously treated with the C3 laser at 1,064 nm using a mean E(max) of 5.8+/-0.8 J/cm(2) (range 3.8-7.5 J/cm(2)) as compared with a mean E(max) of 6.4+/-1.6 J/cm(2) (range 3.2-9.0 J/cm(2)) during the C6 treatment course. Corresponding spot sizes were larger during C6 treatments as compared with C3 (5.0+/-0.9 and 3.6+/-0.2 mm, respectively). The C6 laser had a "flat top" and homogenous profile regardless of the spot size. For the C3 laser the beam shape was "Gaussian," and the homogeneity was reduced by numerous micro-spikes and micro-nadirs. After the C6 treatment course 33.3% of the tattoos showed clearance of grade 1 (0-25%), 16.7% of grade 2 (26-50%), 16.7% of grade 3 (51-75%), 30.5% of grade 4 (76-95%), 2.8% of grade 5 (96-100%). The total rate of side effects due to C6 treatment was 8.3% in all tattoos (hyperpigmentation 5.6%, hypopigmentation 2.7%, textural changes/scars 0%). This clinical study documents for the first time the impact of a 1,064-nm Nd:YAG laser with a more homogenous beam profile and a larger spot size on the management of resistant tattoos. Only a few treatment sessions were necessary to achieve an additional clearance with a low rate of

  7. Q-switched Nd: YAG laser alone or with modified Jessner chemical peeling for treatment of mixed melasma in dark skin types: A comparative clinical, histopathological, and immunohistochemical study. (United States)

    Saleh, Fatma; Moftah, Noha H; Abdel-Azim, Eman; Gharieb, Marwa G


    Treatment of mixed melasma remains challenging. Promising results have been achieved with low-fluence 1064-nm Q-switched Nd-YAG laser; however, multiple sessions are necessary with occurrence of complications especially in dark skin types. So, combination methods may be recommended. To compare efficacy of Q-switched Nd-YAG laser alone or with modified Jessner's peel in mixed melasma in dark skin. Nineteen patients with mixed melasma received 6 sessions of laser on left side of face and alternating laser and modified Jessner on right side. Evaluation was carried out clinically through modified melasma area and severity index at 1 month after last session. Using histopathological, immunohistochemical, and computerized morphometric analysis, objective evaluation of melanin particle surface area and MART-1-positive cells was performed for pre- and post-treated skin biopsies. There was significant clinical improvement on both sides of face (P  .05). At the sixth laser session on left side of face, ill-defined mottled hypopigmentation was observed in 21.05% of patients. Histopathologically, melanin particle surface area and number of MART-1-positive cells (total, epidermal, and dermal) were significantly decreased after two treatment modalities (P  .05). Low-fluence Q-switched Nd-YAG laser alone and with modified Jessner's peel are equally effective regimens for mixed melasma clinically, histopathologically, and immunohistochemically. However, combined method is preferred, especially in dark skin, for obtaining better cosmetic result with fewer side effects of multiple laser sessions and decreasing cost rate of laser. © 2017 Wiley Periodicals, Inc.

  8. Combination of Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, non-ablative 1450-nm diode laser, and ablative 10 600-nm carbon dioxide fractional laser for enlarged pores. (United States)

    Cho, Sung Bin; Noh, Seongmin; Lee, Sang Ju; Kang, Jin Moon; Kim, Young Koo; Lee, Ju Hee


    Currently, there is no gold standard for the treatment of enlarged facial pores. In this report, we describe a patient with enlarged nasal pores which were treated with a combination of a non-ablative 1450-nm diode laser, a Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, and an ablative 10 600-nm carbon dioxide fractional laser system. Four months after the final treatment, the condition of the patient's pores had markedly improved, and the patient was satisfied with the results.

  9. Diode laser in-band pumped, efficient 1645 nm continuous-wave and Q-switched Er:YLuAG lasers with near-diffraction-limited beam quality

    International Nuclear Information System (INIS)

    Li, Jing; Yang, SuHui; He, Tao


    Fiber-like Er:YLuAG laser rods were tested for continuous-wave (CW) and Q-switched operation. Two narrow-band laser diodes emitting at 1532 nm were used as pump sources. The pump power was confined in the laser rods via total internal reflection. In CW mode, a maximum output power of 7.2 W was measured from a 30 mm long Er:YLuAG laser rod, corresponding to an optical–optical efficiency of 26% and a slope efficiency of 78%. Er:YLuAG and Er:YAG lasers were compared experimentally and exhibited comparable performance, while the measured central wavelength of the Er:YLuAG laser was 1644.75 nm, slightly longer than the central wavelength of the Er:YAG laser in the same experimental circumstances. In Q-switched mode, an output energy of 3.5 mJ was obtained from a 25 mm Er:YLuAG laser rod with a pulse duration of 100 ns and a pulse repetition frequency of 100 Hz. The pulsed output had near-diffraction-limited beam quality with M 2 values of 1.13 and 1.11 in the x and y directions, respectively. (letter)

  10. Treatment of tattoos with a 755-nm Q-switched alexandrite laser and novel 1064 nm and 532 nm Nd:YAG laser handpieces pumped by the alexandrite treatment beam. (United States)

    Bernstein, Eric F; Bhawalkar, Jay; Clifford, Joan; Hsia, James


    Multi-colored and even black tattoos often require more than one wavelength to remove the target pigment. The authors report here a novel alexandrite laser with two Nd:YAG laser handpieces pumped by the alexandrite treatment beam enabling the delivery of three wavelengths from a single device. To describe and evaluate the effectiveness of a novel Q-switched laser-pumped laser for treating tattoos. Twenty tattoos in 14 subjects were treated at four-week intervals using a combination of available wavelengths (532, 755 and 1064 nm) as determined by the treating physician. Digital cross-polarized photographs were taken before treatment and two months following the fourth and final treatment. Photographs were evaluated by three physician observers blinded as to the treatment condition and rated for clearance by the following scale: 1 = > 95 percent, 2 = 76-95 percent, 3 = 51-75 percent, 4 = 26-50 percent and 5 = 0-25 percent clearance. The average clearance score was 3.1, in the 51-75 percent range, two months following four treatments. No scarring, hyper- or hypopigmentation was noted on post-treatment photographs or by the treating physician. The alexandrite and alexandrite-pumped 532 nm and 1064 nm Q-switched lasers are effective for removing decorative tattoos, and represents the first commercial laser with laser-pumped, laser handpieces.

  11. Passively Q-switched 1.6 µm Er:YAG laser with a γ-Ga2O3:Co-based glass-ceramics as a saturable absorber (United States)

    Shi, Yang; Gao, Chunqing; Ye, Qing; Wang, Shuo; Wang, Qing; Gao, Mingwei; Loiko, Pavel; Skoptsov, Nikolai; Dymshits, Olga; Zhilin, Alexander; Zapalova, Svetlana; Tsenter, Marina; Vitkin, Vladimir; Mateos, Xavier; Yumashev, Konstantin


    A resonantly pumped passively Q-switched Er:YAG laser operating at 1.617 and 1.645 µm is reported with γ-Ga2O3:Co2+-based glass-ceramics (GCs) as a saturable absorber. The maximum average output power achieved from this laser was 273 mW; the highest pulse energy was 5.9 µJ, corresponding to a pulse duration of 3.0 µs at a repetition frequency of 31 kHz. To the best of our knowledge, this is the first time to use the γ-Ga2O3:Co2+-based GC as a passive Q-switcher for Er:YAG lasers and this is also the first time to obtain 1.617 µm and 1.645 µm pulses with a GC-based saturable absorber.

  12. High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser. (United States)

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


    In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

  13. Novel treatment of Hori′s nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser

    Directory of Open Access Journals (Sweden)

    Brian Wei Cheng Anthony Tian


    Full Text Available Objective: To demonstrate a combination laser therapy to treat Hori′s nevus. Design: A prospective study. Setting: A Singapore-based clinic. Participants: Five female patients, aged 30-46 years, with bilateral malar Hori′s nevus. Measurements: Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. Materials and Methods: The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm 2, spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori′s nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS Nd:YAG at a fluence of 2.0 J/cm 2 , frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori′s nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. Results: All five patients had above 80% improvement in their pigmentation and two (skin type III achieved complete 100% clearance. Based on the patients′ subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. Conclusion: The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori′s nevus.

  14. Novel treatment of Hori's nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser. (United States)

    Tian, Brian Wei Cheng Anthony


    To demonstrate a combination laser therapy to treat Hori's nevus. A prospective study. A Singapore-based clinic. Five female patients, aged 30-46 years, with bilateral malar Hori's nevus. Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm(2), spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori's nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS) Nd:YAG at a fluence of 2.0 J/cm(2), frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori's nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. All five patients had above 80% improvement in their pigmentation and two (skin type III) achieved complete 100% clearance. Based on the patients' subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori's nevus.

  15. Evaluation of frequency-doubled Q-switched Nd: YAG laser in the treatment of freckle%倍频Q开关掺钕钇铝石榴石激光治疗雀斑疗效观察

    Institute of Scientific and Technical Information of China (English)

    罗迪青; 张武军; 刘隽华; 张海燕; 何定阳


    目的 评估倍频Q开关掺钕钇铝石榴石激光治疗雀斑的疗效.方法 总结2004年10月至2007年8月间治疗的47例雀斑患者的资料及治疗后外涂丁卡因凝胶的效果.结果 治疗后6个月,47例患者中,治愈38例(80.9%),显效8例(17.0%),有效1例(2.1%),总有效率100%.1年后治愈率为100%.治疗后3个月时有15例(31.9%)出现色素沉着,但于9个月内全部消退.治疗后外涂丁卡因凝胶的起效时间为20~70 8,达到最大镇痛效果的时间为2~5 min,可以减轻疼痛70%~100%.结论 倍频Q开关Nd:YAG激光治疗雀斑有疗效好、不良反应少的优点.但可出现可逆性炎症后色素沉着.治疗后使用丁卡因凝胶,有较好的止痛效果.%Objective To evaluate the effects of Q-switched Nd: YAG laser in the treatment of freckle. Methods Fourty-seven cases treated by Q-switched Nd: YAG laser between October 2004 to August. 2007 were analyzed. The effects of post-laser treatment of tetracaine gel were evaluated. Results Of 47 cases, 38 were cured (80.9%), 8 were notablely improved (17.0%) and 1 was improved 6 months after treatment. The total efficient rate was 100%. All of them were cured 1 year after treatment. 15 cases had a postinflammatory hyperpigmentation 3 months after the laser treatment which disappeared in 9 months. Furthermore, when the tetracaine gel was used after the laser treatment, the onset time was 20 to 70 seconds, the time of the maxial decreased-pain was 2 to 5 minutes and the maximal decreased-pain was 70%~100%. Conclusions Frequency-doubled Q-switched Nd: YAG laser is an effective tool to treat freckles without any adverse effects. But some of the patients will have a reversible postin-flammatory hyperpigmentation. Tetracaine gel has a rapid and good effects on laser-induced pain when used immedi-ately after laser procedure.

  16. A promising split-lesion technique for rapid tattoo removal using a novel sequential approach of a single sitting of pulsed CO(2) followed by Q-switched Nd: YAG laser (1064 nm). (United States)

    Sardana, Kabir; Garg, Vijay K; Bansal, Shivani; Goel, Khushbu


    Laser tattoo removal conventionally uses Q-switched (QS) lasers, but they require multiple sittings, and the end results depend largely on the type of tattoo treated. In pigmented skin, due to the competing epidermal pigment results, laser results in tattoo are slow and inadequate. To evaluate the efficacy of a combined use of ultrapulse CO2 and QS Nd:YAG (1064 nm) laser in the treatment of tattoos in Indian skin. A split-lesion trial was carried out in five patients, with the left side of tattoos receiving the QS Nd:YAG (1064 nm) and the right side, a sequential combination of Up CO2 and QS Nd: YAG at 6 weeks interval with a maximum of six sittings. Outcome assessment was carried out by a blinded assessor using standardized photography. An assessment of physician improvement score, side-effects score, and patient satisfaction score was taken during and at the end of the study. There was a statistically significant improvement on the combination side(physician improvement score -3.7 vs. 1.87: P = 0.0019) which occurred earlier with fewer sittings (1.7 vs. 6). There was no statistically significant difference in the side effects. A combination of an Up CO2 laser with QS Nd: YAG laser is a promising tool for rapid and effective removal of blue-black/blue amateur tattoo in pigmented skin. © 2013 Wiley Periodicals, Inc.

  17. Efficient, space-based, PM 100W thulium fiber laser for pumping Q-switched 2μm Ho:YLF for global winds and carbon dioxide lidar (United States)

    Engin, Doruk; Mathason, Brian; Storm, Mark


    Global wind measurements are critically needed to improve and extend NOAA weather forecasting that impacts U.S. economic activity such as agriculture crop production, as well as hurricane forecasting, flooding, and FEMA disaster planning.1 NASA and the 2007 National Research Council (NRC) Earth Science Decadal Study have also identified global wind measurements as critical for global change research. NASA has conducted aircraft-based wind lidar measurements using 2 um Ho:YLF lasers, which has shown that robust wind measurements can be made. Fibertek designed and demonstrated a high-efficiency, 100 W average power continuous wave (CW) 1940 nm thulium (Tm)- doped fiber laser bread-board system meeting all requirements for a NASA Earth Science spaceflight 2 μm Ho:YLF pump laser. Our preliminary design shows that it is possible to package the laser for high-reliability spaceflight operation in an ultra-compact 2″x8″x14″ size and weight <8.5 lbs. A spaceflight 100 W polarization maintaining (PM) Tm laser provides a path to space for a pulsed, Q-switched 2 μm Ho:YLF laser with 30-80 mJ/pulse range at 100-200 Hz repletion rates.

  18. Compact intra-cavity pumped low-threshold passively Q-switched Ho:Sc2SiO5 laser by a LD-pumped Tm:YAP laser at room temperature (United States)

    Yang, Xiao-tao; Xie, Wen-qiang; Liu, Long; Li, Lin-jun


    A compact intra-cavity pumped low-threshold passively Q-switched (PQS) Ho:Sc2SiO5 (Ho:SSO) laser is reported for the first time. The Tm:YAlO3 (Tm:YAP) crystal and the Ho:SSO crystal are placed in the same laser cavity. A laser diode with a central wavelength of 793 nm is used to realize the output of the Ho:SSO laser. Both the continuous wave (CW) and PQS operation are investigated. A Cr2+:ZnSe is used as the saturable absorber in the PQS Ho:SSO laser. For the CW mode, the laser threshold is only 750 mW, which is 980 mW in the PQS mode. A maximum pulse energy of 699 µJ is primarily obtained, corresponding to the pulse width of 96 ns. The maximum repetition frequency is 1.46 kHz. The maximum pulse peak power can be calculated to be 7.28 kW. The beam quality factor M 2 is calculated to be 1.4 with the maximum output power.

  19. Over 8 W high peak power UV laser with a high power Q-switched Nd:YVO4 oscillator and the compact extra-cavity sum-frequency mixing

    International Nuclear Information System (INIS)

    Yan, X P; Liu, Q; Gong, M; Wang, D S; Fu, X


    A 8.2 W UV laser was reported with the compact extra-cavity sum-frequency mixing. The IR fundamental frequency source was a high power and high beam quality Q-switched Nd:YVO 4 oscillator. 38 W fundamental frequency laser at 1064 nm was obtained at the pulse repetition rate of 450 kHz with the beam quality factors of M 2 x = 1.27, M 2 y = 1.21. The type I and type II phase-matched LBO crystals were used as the extra-cavity frequency doubling and mixing crystals respectively. At 38 kHz, 8.2 W UV laser at 355 nm was achieved with the pulse duration of 8 ns corresponding to the pulse peak power as high as 27 kW, and the optical-optical conversion efficiency from IR to UV was 25.6%. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated detailedly

  20. Efficient continuous-wave and passively Q-switched pulse laser operations in a diffusion-bonded sapphire/Er:Yb:YAl3(BO3)4/sapphire composite crystal around 1.55 μm. (United States)

    Chen, Yujin; Lin, Yanfu; Huang, Jianhua; Gong, Xinghong; Luo, Zundu; Huang, Yidong


    A composite crystal consisting of a 1.5-mm-thick Er:Yb:YAl 3 (BO 3 ) 4 crystal between two 1.2-mm-thick sapphire crystals was fabricated by the thermal diffusion bonding technique. Compared with a lone Er:Yb:YAl 3 (BO 3 ) 4 crystal measured under the identical experimental conditions, higher laser performances were demonstrated in the sapphire/Er:Yb:YAl 3 (BO 3 ) 4 /sapphire composite crystal due to the reduction of the thermal effects. End-pumped by a 976 nm laser diode in a hemispherical cavity, a 1.55 μm continuous-wave laser with a maximum output power of 1.75 W and a slope efficiency of 36% was obtained in the composite crystal when the incident pump power was 6.54 W. Passively Q-switched by a Co 2+ :MgAl 2 O 4 crystal, a 1.52 μm pulse laser with energy of 10 μJ and repetition frequency of 105 kHz was also realized in the composite crystal. Pulse width was 315 ns. The results show that the sapphire/Er:Yb:YAl 3 (BO 3 ) 4 /sapphire composite crystal is an excellent active element for 1.55 μm laser.

  1. Split-face comparison of long-pulse-duration neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser alone and combination long-pulse and Q-switched Nd:YAG 1,064-nm laser with carbon photoenhancer lotion for the treatment of enlarged pores in Asian women. (United States)

    Wattanakrai, Penpun; Rojhirunsakool, Salinee; Pootongkam, Suwimon


    Long-pulse and Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser used for facial rejuvenation can improve pore size. Topical carbon has been used to enhance efficacy. To compare the efficacy and safety of a 1,064-nm long-pulse Nd:YAG laser alone with that of a combination Q-switched Nd:YAG laser with topical carbon lotion followed by long-pulse Nd:YAG to improve enlarged pores. Twenty Thai women randomly received five treatments with a long-pulse Nd:YAG laser on one facial half (LP side) and long-pulse Nd:YAG after carbon-assisted Q-switched Nd:YAG laser on the contralateral side (carbon QS+LP side) at 2-week intervals. Participants were evaluated using digital photography, complexion analysis, and a chromometer. There was significant decrease in pore counts of 35.5% and 33% from baseline on the carbon QS+LP and LP sides, respectively. Physician-evaluated pore size improvement was 67% on the carbon QS+LP sides and 60% on the LP sides. Chromometer measurement showed an increase in skin lightness index. There was no significant difference between the two treatments, although there were more adverse effects on the carbon QS+LP side. Long-pulse Nd:YAG 1,064-nm laser improves the appearance of facial pores and skin color. Adding carbon-assisted Q-switched Nd:YAG did not enhance the results but produced more side effects. © 2010 by the American Society for Dermatologic Surgery, Inc.

  2. Q-switched nanosecond Nd3+:Ca(NbO3)2 crystalline self-Raman laser with single-step cascade SE (λSE = 1.0615 μm of 4F3/2 → 4I11/2 channel) → SRS (λSt1 = 1.1741 μm of ωSRS ≈ 904 cm-1 promotion vibration mode) wavelength conversion

    International Nuclear Information System (INIS)

    Kaminskii, A A; Dong, J; Ueda, K; Bettinelli, M; Grinberg, M; Jaque, D


    A passively Q-switched nanosecond Nd 3+ :Ca(NbO 3 ) 2 self-Raman laser with 0.808-μm laser-diode pumping has been demonstrated, operating by nonlinear cascaded scheme at converted wavelength of Nd 3+ one-micron stimulated emission

  3. 蛋白胶-罂粟碱复合体促进调Q Nd:YAG激光治疗后创面愈合的观察%Using Fibrin Glue Papaverine Complex to Promote Wounds Healing after Q-Switched Laser

    Institute of Scientific and Technical Information of China (English)

    朱玉; 李栋梁; 陈志勇; 谭强; 周业松


    目的 观察蛋白胶-罂粟碱复合体对调Q Nd:YAG激光治疗后创面愈合的促进作用.方法 太田痣患者50例,随机分为研究组和对照组,每组25例.以调Q Nd:YAG激光治疗后,分别应用蛋白胶-罂粟碱复合体或凡士林纱布覆盖创面,对比观察两组患者创面疼痛评分、止血时间及愈合时间.结果 研究组在创面疼痛评分、止血时间、创面愈合时间均优于对照组.结论 蛋白胶-罂粟碱复合体对调Q Nd:YAG激光治疗后的创面具有明显的减轻疼痛,促进愈合的作用.%Objective To observe the effects of using fibrin glue papaverine complex to promote wound healing after Q-switched laser therapy.Methods Fifty patients with nevus of Ota were randomly and equally assigned to two groupa: the study group applied fibrin glue papaverine complex and the control group applied vaseline gauze,and their wounds pain, hemostatic lime and healing time were compared.Results Covering wounds with glue papaverine complex after Q-switched laser was superior to the other therapy from aspects of pain alleviation, hemostatic time and healing time.Conclusions Covering wounds with glue papaverine complex after the treatment of Q-switched laser can alleviate the pain and accelerate the wound healing.

  4. Ocular hazards of Q-switched near-infrared lasers (United States)

    Lund, David J.; Edsall, Peter R.; Stuck, Bruce E.


    The threshold for laser-induced retinal damage in the rhesus eye was determined for wavelengths between 900 nm and 1300 nm. The laser source was a tunable Optical Parametric Oscillator (OPO) pumped by the 3rd harmonic of a Nd:YAG laser. The laser pulse duration was 3.5 ns. The wavelength dependence of the injury threshold is consistent with the prediction of a model based on the transmission of the preretinal ocular media, absorption in the retinal pigment epithelium, and variation of irradiance diameter resulting from chromatic aberration of the eye optics for wavelengths shorter than 1150 nm but was less consistent for longer wavelengths. The threshold for 24-hour observation was slightly lower than the threshold for 1-hour observation. These data form a basis for reexamination of the currently defined MPEs for wavelengths longer than 1100 nm.

  5. Linearly polarized intracavity passive Q-switched Yb-doped ...

    Indian Academy of Sciences (India)


    Feb 14, 2014 ... ytterbium-doped photonic crystal fibre laser with a Cr4+:YAG crystal ... average output power of 9.4 W with pulse duration of 64 ns and ... applications of nonlinear frequency shifting like frequency doubling and optical paramet-.

  6. Mathematical modeling of a passively Q-switched diode laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.


    A mathematical model describing the dynamic emission of the intracavity frequency doubling (IFD) of a gain-switched InGaAs/GaAs/KTP and a gain-switched mode-locked two-sections tapered ridge-waveguide InGaAs/GaAs diode laser has been presented. The IFD of a gain-switched and a gain-switched mode-locked two-sections diode laser is modeled where one section is electrically pumped to proved gain while the second section is unpumped (reverse biased) to provide a saturable absorber. (author)

  7. Q-switch Nd:YAG laser welding of AISI 304 stainless steel foils

    Energy Technology Data Exchange (ETDEWEB)

    P' ng, Danny [Laboratory for Lasers, MEMS and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States); Molian, Pal [Laboratory for Lasers, MEMS and Nanotechnology, Department of Mechanical Engineering, Iowa State University, Ames, IA 50011-2161 (United States)], E-mail:


    Conventional fusion welding of stainless steel foils (<100 {mu}m thickness) used in computer disk, precision machinery and medical device applications suffer from excessive distortion, formation of discontinuities (pore, void and hot crack), uncontrolled melting (melt-drop through) and poor aesthetics. In this work, a 15 ns pulsed, 400 mJ Nd:YAG laser beam was utilized to overcome these barriers in seam welding of 60 {mu}m thin foil of AISI 304 stainless steel. Transmission electron microscopy was used to characterize the microstructures while hardness and tensile-shear tests were used to evaluate the strengths. Surface roughness was measured using a DekTak profilometer while porosity content was estimated using the light microscope. Results were compared against the data obtained from resistance seam welding. Laser welding, compared to resistance seam welding, required nearly three times less heat input and produced welds having 50% narrower seam, 15% less porosity, 25% stronger and improved surface aesthetics. In addition, there was no evidence of {delta}-ferrite in laser welds, supporting the absence of hot cracking unlike resistance welding.

  8. An in-vitro morphological study of Q-switched neodymium/YAG laser trabeculotomy. (United States)

    Venkatesh, S; Lee, W R; Guthrie, S; Cruickshank, F R; Foulds, W S; Quigley, R J; Bailey, R T


    Laser trabeculotomies produced by directing a pulsed neodymium/YAG laser beam at specimens of human anterior chamber angle obtained post mortem or after enucleation were studied by light microscopy and by scanning and transmission electron microscopy to assess the dimensions of the openings created in the trabecular meshwork, their penetrance to the canal of Schlemm, and the extent or absence of laser induced cellular damage in immediately adjacent tissue. A pulse duration of 40-50 ns at energy levels of around 30 mJ was used and the laser cavity carefully tuned to give a Gaussian spatial mode pattern. Openings in the trabecular meshwork typically of 100 microns in diameter and penetrating through to the canal of Schlemm could be regularly created with only minimal damage to adjacent tissue as judged by transmission electron microscopy. The information so gained may be useful in determining the parameters required for successful laser trabeculotomy as a treatment for primary open-angle glaucoma.

  9. Ultra-Stable, New Generation Q-Switched Monolithic Laser Cleaners for Fine Art Conservation (United States)

    Brioschi, F.; Salvadeo, P.

    The increasing use of laser cleaners in fine art conservation boosts the demand on improvements of the laser performances. More power and more wavelengths are required by the current applications, while laser should be more reliable, rugged and compact. The characteristics and performances of a new generation of laser cleaners are presented as a result of a dedicated research and development program.

  10. Resonant photoacoustic detection of NO2 traces with a Q-switched green laser (United States)

    Slezak, Verónica; Codnia, Jorge; Peuriot, Alejandro L.; Santiago, Guillermo


    Resonant photoacoustic detection of NO2 traces by means of a high repetition pulsed green laser is presented. The resonator is a cylindrical Pyrex glass cell with a measured Q factor 380 for the first radial mode in air at atmospheric pressure. The system is calibrated with known mixtures in dry air and a minimum detectable volume concentration of 50 parts in 109 is obtained (S/N=1). Its sensitivity allows one to detect and quantify NO2 traces in the exhaust gases of cars. Previously, the analysis of gas adsorption and desorption on the walls and of changes in the sample composition is carried out in order to minimize errors in the determination of NO2 content upon application of the extractive method. The efficiency of catalytic converters of several models of automobiles is studied and the NO2 concentration in samples from exhausts of different types of engine (gasoline, diesel, and methane gas) at idling operation are measured.

  11. High-Power Dual-End-Pumped Actively Q-Switched Ho:YAG Ceramic Laser (United States)

    Duan, Xiao-Ming; Yuan, Jin-He; Yao, Bao-Quan; Dai, Tong-Yu; Li, Jiang; Pan, Yu-Bai


    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 61308009, 61405047 and 50990301, the China Postdoctoral Science Foundation Funded Project under Grant No 2015T80339, the Fundamental Research Funds for the Central Universities under Grant No HIT.NSRIF.2015042, and the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310.

  12. Passively Q-switched ytterbium- and chromium-doped all-fiber laser

    Czech Academy of Sciences Publication Activity Database

    Dussardier, B.; Maria, J.; Peterka, Pavel


    Roč. 50, č. 25 (2011), E20-E23 ISSN 0003-6935 R&D Projects: GA MŠk(CZ) ME10119 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical fiber * fiber lasers * fiber amplifiers Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.703, year: 2010

  13. Retinal hemorrhage thresholds for Q-switched neodymium-Yag laser exposures

    Energy Technology Data Exchange (ETDEWEB)

    Blankenstein, M.F.; Zuclich, J.; Allen, R.G.; Davis, H.; Thomas, S.J.; Harrison, R.F.


    Thresholds for retinal vitreal and contained hemorrhages were determined for 1064 nm laser light at 30-nsec and 4-nsec pulsewidths. Rhesus monkeys received graded exposures from a neodymium-yag laser onto either the macular or extramacular region of the retina. Contained hemorrhages appeared as concentric ring structures with white punctate centers. The vitreal hemorrhage was characterized by the presence of choroidal blood in the vitreal chamber at the exposure site. The 30-nsec contained hemorrhage threshold (ED50) was 1.7 mJ on the macula and 2.1 mJ for an extramacular exposure. The 30-nsec vitreal hemorrhage macular threshold was 2.3 mJ, and the extramacular threshold was 6.6 mJ. The threshold for the 4-nsec pulsewidths to produce a hemorrhage (vitreal or contained) on the retina (macula or extramacular) was 340 microJ.

  14. Retinal-hemorrhage thresholds for Q-switched neodymium-YAG laser exposures

    Energy Technology Data Exchange (ETDEWEB)

    Blankenstein, M.F.; Zuclich; Allen, R.G.; Davis; Thomas, S.J.


    Thresholds for retinal vitreal and contained hemorrhages were determined for 1064-nm laser light at 30-ns and 4-ns pulsewidths. Rhesus monkeys received graded exposures from a neodymium-YAG laser onto either the macular or extramacular region of the retina. Contained hemorrhages appeared as concentric-ring structures with white punctuate centers. The vitreal hemorrhage was characterized by the presence of choroidal blood in the vitreal chamber at the exposure site. The 30-ns contained-hemorrhage threshold (ED50) was 1.7 mJ on the macula and 2.1 mJ for an extramacular exposure. The 30-ns vitreal-hemorrhage macular threshold was 2.3 mJ, and the extramacular threshold was 6.6 Mj. The threshold for the 4-ns pulse widths to produce a hemorrhage (vitreal or contained) on the retina (macula or extramacular) was 340 uJ.

  15. Clinical and histological responses of congenital melanocytic nevi after single treatment with Q-switched lasers

    NARCIS (Netherlands)

    Grevelink, JM; vanLeeuwen, RL; Anderson, RR; Byers, HR

    Background: Laser irradiation of congenital melanocytic nevi is a controversial treatment. Recurrence of lesions after laser treatment appears to be the rule, and the effects of laser irradiation on cellular biological behavior and the possible mutagenic responses of nevomelanocytes that have

  16. Diode array pumped, non-linear mirror Q-switched and mode-locked ...

    Indian Academy of Sciences (India)

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic ... effects such as all-optical switching [7,8], nearly degenerate four-wave mixing [9,10], .... is driven by a radio frequency signal of 27.2MHz with a modulation available in.

  17. Q-switched YAG laser vs. punch biopsy excision for iatrogenic radiation tattoo markers--a randomized controlled trial

    DEFF Research Database (Denmark)

    Bregnhøj, A; Haedersdal, M


    Ink markers are tattooed as landmarks before radiotherapy of breast cancer with the purpose of obtaining a precise radiation field. The black tattoo spots may cause potential psychological distress for the affected women.......Ink markers are tattooed as landmarks before radiotherapy of breast cancer with the purpose of obtaining a precise radiation field. The black tattoo spots may cause potential psychological distress for the affected women....

  18. Stable narrow spacing dual-wavelength Q-switched graphene oxide embedded in a photonic crystal fiber

    International Nuclear Information System (INIS)

    Ahmad, H; Soltanian, M R K; Alimadad, M; Harun, S W


    An ultra-stable dual-wavelength saturable absorber based on a cladding-embedded commercial graphene oxide (GO) solution by capillary action in a solid core photonic crystal fiber (PCF) is demonstrated for the first time. The saturation absorption property is achieved through evanescent coupling between the guided light and the cladding-filled graphene layers. Stable spacing dual-wavelength fiber lasing is attained by controlling the polarization state of a simple 0.9 m long ring of highly doped Leikki Er80-8/125 erbium-doped fiber as the primary gain medium with PCF, polarization controller and tunable bandpass filter. Embedded GO is used to generate the desired pulsed output, and the laser is capable of generating pulses having a repetition rate of 24 kHz with an average output power and pulse energy of 0.167 mW and 8.98 nJ, respectively, at the maximum pump power of 220 mW. (paper)

  19. Quasi-CW diode-pumped self-starting adaptive laser with self-Q-switched output. (United States)

    Smith, G; Damzen, M J


    An investigation is made into a quasi-CW (QCW) diode-pumped holographic adaptive laser utilising an ultra high gain (approximately 10(4)) Nd:YVO(4) bounce amplifier. The laser produces pulses at 1064 nm with energy approximately 0.6 mJ, duration laser configuration, the output was amplified to obtain pulses of approximately 5.6 mJ energy, approximately 7 ns duration and approximately 1 MW peak power. The output spatial quality is also M(2)diode-pumped self-adaptive holographic lasers can provide a useful source of high peak power, short duration pulses with excellent spatial quality and narrow linewidth spectrum.

  20. Diode-Pumped, 2-Micron, Q-Switched Thulium: Y3Al5O12 (Tm:Yag) Microchip Laser (United States)


    Estimating Beam Quality The beam parameter product ( BPP ), which is defined as the product of a beam’s divergence half-angle and its radius at the a figure of merit describing how well the beam can be focused to a small spot. The BPP of an ideal Gaussian beam is given by λ/π, where λ is the...beam’s wavelength. A second quantity, M2, also called the Gaussian beam parameter, is defined as the ratio of a measured BPP to an ideal BPP at

  1. A Mid-IR Optical Parametric Oscillator Pumped by an Actively Q-Switched Ho:YAG Ceramic Laser (United States)

    Yuan, Jin-He; Duan, Xiao-Ming; Yao, Bao-Quan; Li, Jiang; Shen, Ying-Jie; Cui, Zheng; Dai, Tong-Yu; Pan, Yu-Bai


    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 61308009, 61405047 and 50990301, the Fundamental Research Funds for the Central Universities under Grant Nos HIT.NSRIF.2014044 and HIT.NSRIF.2015042, and the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310.

  2. Efficient diode-end-pumped actively Q-switched Nd:YAG/SrWO4/KTP yellow laser. (United States)

    Cong, Zhenhua; Zhang, Xingyu; Wang, Qingpu; Liu, Zhaojun; Li, Shutao; Chen, Xiaohan; Zhang, Xiaolei; Fan, Shuzhen; Zhang, Huaijin; Tao, Xutang


    An efficient intracavity frequency-doubled Raman laser was obtained by using an SrWO(4) Raman medium, an Nd:YAG ceramic gain medium, and a KTP frequency-doubling medium. Three laser cavities, including a two-mirror cavity, a three-mirror coupled cavity, and a folded cavity, were investigated. With the coupled cavity, a 2.93 W, 590 nm laser was obtained at an incident pump power of 16.2 W and a pulse repetition frequency of 20 kHz; the corresponding conversion efficiency was 18.1%. The highest conversion efficiency of 19.2% was obtained at an incident pump power of 14.1 W and a pulse repetition frequency of 15 kHz. The obtained maximum output power and conversion efficiency were much higher than the results previously obtained with intracavity frequency-doubled solid-state Raman lasers.

  3. Stable polarization short pulse passively Q-switched monolithic microchip laser with [110] cut Cr4+:YAG

    International Nuclear Information System (INIS)

    Wang, Y; Gong, M; Yan, P; Huang, L; Li, D


    A monolithic Nd:YAG microchip laser with [110] cut Cr 4+ :YAG is presented. The output beam is linearly polarized with polarization ratio higher than 100:1. The polarization direction is stable, independent of pump power, crystal temperature, LD temperature. In single longitudinal mode operation, stable 259 ps pulses at 2.5 kHz with 82 kW peak power and diffraction limited beam mode are output. With a simple and compact one-pass Nd:YVO 4 amplifier, 144 kW peak power is achieved. Single longitudinal and fundamental transverse mode is kept after passing through the amplifier stage. The microchip laser can be operated in two longitudinal modes with two sets of output pulses by increasing the pump power

  4. A 9.61-W, b-cut Tm,Ho:YAP laser in Q-switched mode operation (United States)

    Li, Guoxing; Yang, Xining; Zhang, Ziqiu; Zhang, Hongda; Zhang, Liang


    A high energy of b-cut Tm, Ho:YAlO3 laser is reported in the paper. The laser operated in acousto-optical Qswitched mode at 2.12 μm. The output average power of 9.61 W was achieved at the pulse repetition frequency of 10 kHz ,and the power of 11.6 W was acquired in continuous wave mode. Moreover, the energy per pulse of 0.961 mJ in 64.4 ns was acquired at 10 kHz with a 14.92-kW peak power.

  5. Quantum gate for Q switching in monolithic photonic-band-gap cavities containing two-level atoms

    International Nuclear Information System (INIS)

    Greentree, Andrew D.; Prawer, Steven; Hollenberg, Lloyd C. L.; Salzman, J.


    Photonic-band-gap cavities are prime solid-state systems to investigate light-matter interactions in the strong coupling regime. However, as the cavity is defined by the geometry of the periodic dielectric pattern, cavity control in a monolithic structure can be problematic. Thus, either the state coherence is limited by the read-out channel, or in a high-Q cavity, it is nearly decoupled from the external world, making measurement of the state extremely challenging. We present here a method for ameliorating these difficulties by using a coupled cavity arrangement, where one cavity acts as a switch for the other cavity, tuned by control of the atomic transition

  6. XPS and SIMS study of aluminium native oxide modifications induced by Q-switched Nd :YAG laser treatment

    CSIR Research Space (South Africa)

    Barnier, V


    Full Text Available with fluences between 0.7 and 1.7 J/cm2, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) revealed thermal oxidation with an increase of the oxide-layer thickness for 0.7–1.3 J/cm2. Above a threshold at about 1.3 J/cm2 the oxide...

  7. Ablation of Porcine Ligamentum Flavum with Ho:YAG, Q-Switched Ho:YAG, and Quadrupled Nd:YAG Lasers (United States)


    majority of LSS patients is the  thickening of the collagenous connective tissue  bridging  the interlaminar spaces of the dorsal spinal  canal called the...dorsal surface of  the spinal canal and the associated LF segments  bridging  each vertebral level. LF was subsequently  excised from its superior and...secured to a  moveable  optical stage, allowing for very fine mechanical control of the laser‐fiber  relative to the LF. The optical stage was used to

  8. 16.7 W 885 nm diode-side-pumped actively Q -switched Nd:YAG/YVO4 intracavity Raman laser at 1176 nm

    International Nuclear Information System (INIS)

    Jiang, Pengbo; Zhang, Guizhong; Liu, Jian; Ding, Xin; Sheng, Quan; Sun, Bing; Shi, Rui; Wu, Liang; Yao, Jianquan; Yu, Xuanyi; Wang, Rui


    We proposed and experimentally demonstrated the generation of high-power 1176 nm Stokes wave by frequency shifting of a 885 nm diode-side-pumped Nd:YAG laser using a YVO 4 crystal in a Z -shaped cavity configuration. Employing the 885 nm diode-side-pumped scheme and the Z -shaped cavity, for the first time to our knowledge, we realized the thermal management effectively, achieving excellent 1176 nm Stokes wave consequently. With an incident pump power of ∼190.0 W, a maximum average output power of 16.7 W was obtained at the pulse repetition frequency of 10 kHz. The pulse duration and spectrum linewidth of the Stokes wave at the maximum output power were 20.3 ns and ∼0.08 nm, respectively. (paper)

  9. Continuous-wave and passively Q-switched cryogenic Yb: KLu(WO.sub.4./sub.).sub.2./sub. laser

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Petr; Jambunathan, Venkatesan; Paul David, Samuel; Yue, Fangxin; Serres, J.M.; Mateos, X.; Aguilo, M.; Diaz, F.; Griebner, U.; Petrov, V.; Lucianetti, Antonio; Mocek, Tomáš


    Roč. 25, č. 21 (2017), s. 25886-25893 ISSN 1094-4087 R&D Projects: GA MŠk LO1602; GA MŠk LM2015086 EU Projects: European Commission(XE) 739573 - HiLASE CoE Grant - others:OP VVV - HiLASE-CoE(XE) CZ.02.1.01/0.0/0.0/15_006/0000674 Institutional support: RVO:68378271 Keywords : diode-pumped lasers * laser materials Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 3.307, year: 2016

  10. Low-Cost Real-Time Gas Monitoring Using a Laser Plasma Induced by a Third Harmonic Q-Switched Nd-YAG Laser

    Directory of Open Access Journals (Sweden)

    Syahrun Nur Abdulmadjid


    Full Text Available A gas plasma induced by a third harmonic Nd-YAG laser with relatively low pulsed energy (about 10 mJ has favorable characteristics for gas analysis due to its low background characteristics, nevertheless a high power fundamental Nd-YAG laser (100-200 mJ is widely used for laser gas breakdown spectroscopy. The air plasma can be used as a low-cost real-time gas monitoring system such that it can be used to detect the local absolute humidity, while a helium plasma can be used for gas analysis with a high level of sensitivity. A new technique using a helium plasma to improve laser ablation emission spectroscopy is proposed. Namely, the third harmonic Nd-YAG laser is focused at a point located some distance from the target in the 1-atm helium surrounding gas. By using this method, the ablated vapor from the target is excited through helium atoms in a metastable state in the helium plasma.

  11. New advances in 2-μm high-power dual-frequency single-mode Q-switched Ho:YLF laser for dial and IPDA application (United States)

    Gibert, F.; Edouart, D.; Cénac, C.; Le Mounier, F.; Dumas, A.


    In the absence of climate change policies, the fossil fuel emissions are projected to increase in the next decades. Depending on how the current carbon sinks change in the future, the atmospheric CO2 concentration is predicted to be between 700-1000 ppmv by 2100, and global mean surface temperature between 1.1-6.4°C, with related changes in sea-level, extreme events and ecosystem drifts. Keeping the atmospheric CO2 concentration at a level that prevents dangerous interference with the climate system poses an unprecedent but necessary challenge to humanity. Beyond this point, global climate change would be very difficult and costly to deal with. There are two main approaches that are currently analysed: (1) to reduce emissions; (2) to capture CO2 and store it, i.e. sequestration. For these two ways, some monitoring at different scales ultimately from space would be needed. Lidar remote sensing is a powerful technique that enables measurements at various space and time resolution.

  12. Grado de aclaramiento de tatuajes y eventos adversos, posterior a una sesión con láser q-switch


    Garcia Serrano, Sylvia Juliana


    Introducción: Los resultados de la remoción de tatuajes con láser de sesión a sesión según los parámetros utilizados son limitados en la literatura. Objetivo: Evaluar los cambios en el aclaramiento de tatuajes y factores asociados posterior a una sesión con láser y los efectos adversos. Materiales y Métodos: Estudio longitudinal retrospectivo de antes y después de 1 sesión de con láser para remoción de tatuajes, donde se determinaron parámetros del tratamiento, aclaramiento y efectos adversos...

  13. High-power repetitively pulsed CO{sub 2} laser with mechanical Q-switching and its application to studies in aerodynamic installations

    Energy Technology Data Exchange (ETDEWEB)

    Malov, Aleksei N; Orishich, Anatolii M; Shulyat' ev, Viktor B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)


    A new method for organising the repetitively pulsed regime of CO{sub 2} laser oscillation at the expense of a self-filtering resonator and two concave cylindrical mirrors with equal curvature in the intracavity modulator is considered. The studies of the energy and temporal characteristics of the laser radiation show that the constructed laser has high efficiency close to that of a cw laser. The mean and pulse power of 4.5 and 200 kW, respectively, are obtained. For a wide range of gas-dynamic characteristics the possibility of the optical breakdown in the supersonic wide-aperture air flow is demonstrated. The coefficient of absorption of laser radiation in optical breakdown plasma in a supersonic air flow is investigated and its value amounting to 60% is obtained. For the first time it is found that the threshold density of air, corresponding to the efficiency jump, is equal to 1.8 - 2 kg m{sup -3} and independent of the Mach number M = 1.7 - 3.7. (lasers)

  14. SPECIAL ISSUE DEVOTED TO THE 25th ANNIVERSARY OF THE A.M. PROKHOROV GENERAL PHYSICS INSTITUTE: High-speed ablation of ultradeep channels by a phase-conjugate dynamically controlled passively Q-switched Nd:YAG laser (United States)

    Basiev, T. T.; Garnov, S. V.; Klimentov, S. M.; Pivovarov, P. A.; Gavrilov, A. V.; Smetanin, S. N.; Solokhin, S. A.; Fedin, A. V.


    Parameters of high-speed ablation of ultradeep channels by controlled pulse trains from a single-mode phase-conjugate dynamic cavity Nd:YAG laser emitting 20-200-ns, 70-250-mJ pulses at a pulse repetition rate in a train of 40-250 kHz are studied. The optimal parameters of ablation are found, for which a long-lived region of a hot rarefied gas was maintained in the ultradeep channel, which suppressed the shielding action of the surface plasma. The control of the lasing process during ablation optimises not only the heating and plasma formation, but also the removal of the processed material in the pause between laser pulses. Adaptive regulation of lasing parameters during ablation made it possible to obtain ultradeep channels of length 8-27 mm and diameters 80-300 μm of the input and output holes in metals (aluminium, steel and Inconel 718 nickel superalloy) and ultrahard ceramics (Al2O3, AlN, SiC).

  15. Impact of the phase-mismatch in the SHG crystal and consequential self-action of the fundamental wave by cascaded second-order effects on the THG efficiency of a Q-switched 1342 nm Nd:YVO₄ laser. (United States)

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


    We report on the influence of self-focusing and self-defocusing in the phase-mismatched frequency doubling crystal on the third harmonic generation (THG) efficiency in a two crystal frequency tripling scheme. By detuning the temperature of the doubling crystal, the impact of a phase-mismatch in second harmonic generation (SHG) on the subsequent sum frequency mixing process was investigated. It was found that adjusting the temperature not only affected the power ratio of the second harmonic to the fundamental but also the beam diameter of the fundamental beam in the THG crystal, which was caused by self-focusing and self-defocusing of the fundamental beam, respectively. This self-action was induced by a cascaded χ(2) : χ(2) process in the phase-mismatched SHG crystal. Self-defocusing was observable for positive detuning and self-focusing for negative detuning of the phase-matching temperature. Hence, the THG efficiency was not symmetric with respect to the point of optimum phase-matching. Optimum THG was obtained for positive detuning and the resulting self-defocusing in combination with the focusing lens in front of the THG stage was also beneficial for the beam quality of the third harmonic.

  16. Suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding. (United States)

    Huss, Rafael; Wilhelm, Ralf; Kolleck, Christian; Neumann, Jörg; Kracht, Dietmar


    The onset of parasitic oscillations limits the extraction efficiency and therefore energy scaling of Q-switched lasers. A solid-state laser was end pumped with a fiber-coupled diode laser and operated in q-cw as well as in passively Q-switched operation. For Q-switched operation, we demonstrate the suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding.

  17. Design and Development of Intracavity Optical Parametric Oscillator-based Eye Safe Laser Operating at 20 Hz without Forced Air Cooling


    Atul Bhardwaj; Lalita Agrawal; A. K. Maini


    In this paper we report the design and development of an electro-optically Q-switched diode pumped Nd:YAG laser with intracavity optical parametric oscillator, generating ~ 5 ns laser pulses of ~8 mJ energy at eye safe wavelength of 1534 nm. A Z-shaped laser resonator has been designed with porro prism end reflector in Q-switch arm containing RTP Q-Switch and a suitably oriented waveplate. The gain arm consists of a Ø3 x 72 mm Nd: YAG laser rod, pumped from one side by 3 x 5 bar laser diode a...

  18. Effect of temperature on the characteristics of ZnO nanoparticles ...

    Indian Academy of Sciences (India)


    Jan 9, 2016 ... The fundamental wavelength of a Q-switched Nd:YAG laser ... The produced NPs were diagnosed by UV–vis–NIR spectroscopy, X-ray diffraction method, transmission electron ... passing pure oxygen gas simultaneously.

  19. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Dual wavelength operation in diode-end-pumped hybrid vanadate laser ... Efficient and high-power green beam generation by frequency doubling of .... Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser.

  20. Nd:YAG Lasers Treating of Carious Lesion and Root Canal In Vitro

    Directory of Open Access Journals (Sweden)

    Danqing Xia


    Full Text Available Dental caries is a transmissible bacterial disease process, with cavities at the end, and caused by acids from bacterial metabolism. The essence of dental treatment is to clean and disinfect bacterial contamination from the tooth. In this work, we tried to demonstrate the cleaning and disinfecting effects of Nd:YAG laser irradiation on dental carious lesion and root canal in vitro. Acousto-optic Q-switched quasicontinuous and Cr3+:YAG crystal Q-switched pulse Nd:YAG lasers were employed to treat caries lesion and the root canal, respectively. Results showed that acousto-optic Q-switched quasicontinuous Nd:YAG laser irradiation and Cr3+:YAG crystal Q-switched pulse Nd:YAG laser irradiation could rapidly clean decayed material and bacterial contamination from dental carious lesion and the narrow tail end of root canal with minimally invasive in vitro, respectively. It was concluded that acousto-optic Q-switched quasicontinuous laser irradiation may be a rapid and effective alternative caries treatment, and Cr3+:YAG crystal Q-switched pulse Nd:YAG laser irradiation may be an effective method for canal cleaning and disinfecting during root canal therapy.

  1. Characteristic analysis of a polarization output coupling Porro prism resonator (United States)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao


    An Electro-optical Q-switched Nd:YAG slab laser with a crossed misalignment Porro prism resonator for space applications has been theoretically and experimentally investigated. The phase shift induced by the combination of different wave plates and Porro prism azimuth angles have been studied for creating high loss condition prior to Q-switching. The relationship of the effective output coupling reflectivity and the employed Q-switch driving voltage is explored by using Jones matrix optics. In the experiment, the maximum output pulse energy of 93 mJ with 14-ns pulse duration is obtained at the repetition rate of 20 Hz and the optical-to-optical conversion efficiency is 16.8%. The beam quality factors are M 2 x = 2.5 and M 2y = 2.2, respectively.

  2. A widespread allergic reaction to black tattoo ink caused by laser treatment. (United States)

    Bernstein, Eric F


    This is the first reported case of a local and widespread reaction in a 39 year old woman, to black tattoo ink, induced by Q-switched laser treatment. A 39 year old woman was treated with the Q-switched Nd:YAG laser for removal of a decorative tattoo of her lower back. Subsequent to laser treatment, a severe, widespread allergic reaction developed within and surrounding the treated tattoo. Tattoo reactions subsequent to laser treatment should be considered in addition to reactions to topical antibiotics or wound dressings, following laser treatment of tattoos. © 2015 Wiley Periodicals, Inc.

  3. CW and pulsed operation of a diode-end-pumped Tm:GdVO4 laser at room temperature

    International Nuclear Information System (INIS)

    Wang, Z G; Song, C W; Li, Y F; Ju, Y L; Wang, Y Z


    A room-temperature diode-end-pumped acousto-optical (AO) Q-switched Tm:GdVO 4 laser was firstly reported. The minimum AO Q-switch pulse width was measured to be about 48 ns with output power of 2 W and repetition rate of 5 kHz. Continuous-wave output power of 2.8 W at 1912 nm was obtained under the absorbed pump power of 15 W. In addition, laser pulse widths and the ratio of QCW power/CW power at different repetition rates were discussed

  4. Experimental demonstration of an Er-doped fiber ring laser mode-locked with a Tm–Ho co-doped fiber saturable absorber

    International Nuclear Information System (INIS)

    Tao, Mengmeng; Wu, Junjie; Wu, Yong; Yang, Pengling; Ye, Xisheng; Peng, Junsong


    Mode-locking operation of an Er-doped fiber laser with a Tm–Ho co-doped fiber saturable absorber is demonstrated for the first time. Q-switching, Q-switched mode-locking and CW mode-locking operation modes are observed sequentially with increase of the pump power. In the mode-locking operation mode, a repetition rate at the fundamental cavity frequency of 9.05 MHz is obtained with a pulse duration of 46.3 ns. By rotating the polarization controller, a repetition rate up to 887 MHz is achieved, and the pulse duration is shortened to 0.548 ns. (paper)

  5. Laugier-hunziker syndrome: A rare cause of oral and acral pigmentation

    Directory of Open Access Journals (Sweden)

    Silonie Sachdeva


    Full Text Available Laugier-Hunziker syndrome (LHS is an acquired, benign pigmentary skin condition involving oral cavity including lower lip in the form of brown black macules 1-5 mm in size, frequently associated with longitudinal melanonychia. There is no underlying systemic abnormality or malignant predisposition associated with LHS, and therefore the prognosis is good. Important differential diagnoses include Peutz Jeghers syndrome and Addison′s disease among other causes of oral and acral pigmentation. Treatment is sought mainly for cosmetic reasons and Q-switched Nd-Yag laser/ Q-switched alexandrite therapy and cryosurgery have been tried with varying success.


    Directory of Open Access Journals (Sweden)

    K. N. Gorbachenya


    Full Text Available Diode-pumped passively Q-switched microchip Er,Yb:YAl3(BO34 laser for range-finding has been demonstrated. By using a Co2+:MgAl2O4 as a saturable absorber TEM00–mode Q-switched average output power of 315 mW was demonstrated at 1522 nm with pulse duration of 5 ns and pulse energy of 5,25 μJ at a repetition rate of 60 kHz.

  7. Improvements of the ruby laser oscillator system for laser scattering

    International Nuclear Information System (INIS)

    Yamauchi, Toshihiko; Kumagai, Katsuaki; Kawakami, Tomohide; Matoba, Tohru; Funahashi, Akimasa


    A ruby laser oscillator system is used to measure electron temperatures of the Tokamak plasmas(JFT-2 and JFT-2a). Improvements have been made of the laser oscillator to obtain the correct values. Described are the improvements and the damages of a ruby rod and a KD*P crystal for Q-switching by laser beam. Improvement are the linear Xe lamp replaced by a helical Xe lamp and in the electrical circuit for Q-switching. The damage of an optical component by a laser beam should be clarified from the damage data; the cause is not found yet. (author)

  8. Laser tattoo removal with preceding ablative fractional treatment (United States)

    Cencič, Boris; Možina, Janez; Jezeršek, Matija


    A combined laser tattoo removal treatment, first the ablative fractional resurfacing (AFR) with an Er:YAG laser and then the q-switched (QSW) Nd:YAG laser treatment, was studied. Experiments show that significantly higher fluences can be used for the same tissue damage levels.

  9. Effect of Nd 3+ concentration on CW and pulsed performance of ...

    Indian Academy of Sciences (India)

    Q-switching was done with the help of an acousto-optic modulator and we have compared the pulses obtained from Nd : YVO4 laser with different doping concentration. It was found that the 1 at. ... S K Sharma1 T P S Nathan1. Diode Pumped Solid State Laser Group, Center for Advanced Technology, Indore 452 013, India ...


    Indian Academy of Sciences (India)

    microscopic techniques for imaging cell ... Q-switched Yb-doped photonic crystal fibre laser ... Classical simulations of heavy-ion fusion .... functionalized graphene ... Li Hui-Jia see Hu Ke. 571. Lin Huini. Finite-time synchronization of a class of.

  11. Measurement of Minority-Carrier Lifetime in Silicon Solar Cells by ...

    African Journals Online (AJOL)

    This manuscript describes the measurement of minority - carrier lifetime of silicon solar cells, at room temperature, by photoconductive decay method. The Holobeam, Model 655 Double-Pulsed Holographic system, is used as the light source. This consists of a Q-switched, pulsed ruby laser oscillator with two ruby laser ...

  12. Macroparticle acceleration by laser induced ablation pressure

    International Nuclear Information System (INIS)

    Burgess, M.D.J.; Motz, H.; Rumsby, P.T.


    In this paper it is shown that the theoretical scaling of plasma pressure is very closely obeyed using ordinary Q-switched laser pulses, resulting in velocities of over 2 x 10 4 cm s -1 . The problems associated with increasing this velocity whilst still not rupturing the pellet have also been examined and an experiment to determine the results described. (orig.) [de

  13. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Operational characteristics of dual gain single cavity Nd:YVO4 laser · Pranab K Mukhopadhyay Jogy George S K .... Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity · S K Sharma A J Singh P K Mukhopadhyay S M ...

  14. Evaluation of laser cleaning for the restoration of tarnished silver artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Palomar, T., E-mail: [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Depto. de Conservação e Restauro and Research Unit VICARTE-Vidro e Cerâmica para as Artes, Campus de Caparica, FCT-UNL, Quinta da Torre, 2829-516 Caparica (Portugal); Oujja, M. [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid (Spain); Llorente, I.; Ramírez Barat, B. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Cañamares, M.V. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid (Spain); Cano, E. [Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Castillejo, M. [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid (Spain)


    Highlights: • Cyclic application of Q-switched Nd:YAG laser cleaning induces irreversible changes on pure silver. • Laser cleaning using Q-switched Nd:YAG laser at 1064 nm induces loss of material and color changes. • Laser cleaning using Q-switched Nd:YAG laser at 532 nm seems the most appropriate for cleaning sterling silver objects. - Abstract: In this study we evaluate the laser cleaning of tarnished pure and sterling silver substrates using a nanosecond Q-switched Nd:YAG laser at 1064, 532 and 266 nm. To assess the effects associated with cyclic laser cleaning treatments, several cycles of tarnishing followed by laser cleaning were applied on silver coupons that were characterized by gravimetry, colorimetry, scanning electron microscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. According to the obtained results, none of the three wavelengths is recommended for laser cleaning of pure silver objects, while for sterling silver artifacts, the visible laser wavelength of 532 nm seems the most appropriate.

  15. Ultra-broadband nonlinear saturable absorption of high-yield MoS2 nanosheets (United States)

    Wei, Rongfei; Zhang, Hang; Hu, Zhongliang; Qiao, Tian; He, Xin; Guo, Qiangbing; Tian, Xiangling; Chen, Zhi; Qiu, Jianrong


    High-yield MoS2 nanosheets with strong nonlinear optical (NLO) responses in a broad near-infrared range were synthesized by a facile hydrothermal method. The observation of saturable absorption, which was excited by the light with photon energy smaller than the gap energy of MoS2, can be attributed to the enhancement of the hybridization between the Mo d-orbital and S p-orbital by the oxygen incorporation into MoS2. High-yield MoS2 nanosheets with high modulation depth and large saturable intensity generated a stable, passively Q-switched fiber laser pulse at 1.56 μm. The high output power of 1.08 mW can be attained under a very low pump power of 30.87 mW. Compared to recently reported passively Q-switched fiber lasers utilizing exfoliated MoS2 nanosheets, the efficiency of the laser for our passive Q-switching operation is larger and reaches 3.50%. This research may extend the understanding on the NLO properties of MoS2 and indicate the feasibility of the high-yield MoS2 nanosheets to passively Q-switched fiber laser effectively at low pump strengths.

  16. Laser induced breakdown spectroscopy in water | Boudjemai ...

    African Journals Online (AJOL)

    Sparks were generated in water by the focused beam of a Q-switched Nd:YAG laser Na and Cu aqueous solutions exhibited fluorescence signal on the decaying edge of plasma emission at their respective characteristic resonance lines. Potential of the laser plasma spectroscopy for in-situ pollution monitoring in natural ...

  17. Ultrafast pulse generation in integrated arrays of anapole nanolasers

    KAUST Repository

    Gongora, J. S. Totero; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Fratalocchi, Andrea


    via external active components, such as, e.g., Q-switch or saturable absorbers. Consequently, the required optical setups are complex and difficult to integrate on-chip. To address these difficulties, we propose a novel type of integrated source based

  18. Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications (United States)

    Bai, Yingxin; Yu, Jirong; Wong, Teh-Hwa; Chen, Songsheng; Petros, Mulugeta; Singh, Upendra N.


    A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW.

  19. Photoacoustic mammography laboratory prototype: imaging of breast tissue phantoms

    NARCIS (Netherlands)

    Manohar, Srirang; Kharine, Alexei; van Hespen, Johan C. G.; Steenbergen, Wiendelt; van Leeuwen, Ton G.


    We present a laboratory version of a photoacoustic mammoscope, based on a parallel plate geometry. The instrument is built around a flat high-density ultrasound detector matrix. The light source is a Q-switched Nd:YAG laser with a pulse duration of 5 ns. To test the instrument, a novel photoacoustic

  20. Towards the Fourier limit on the super-ACO Storage Ring FEL

    International Nuclear Information System (INIS)

    Couprie, M.E.; De Ninno, G.; Moneron, G.; Nutarelli, D.; Hirsch, M.; Garzella, D.; Renault, E.; Roux, R.; Thomas, C.


    Systematic studies on the Free Electron Laser (FEL) line and micropulse have been performed on the Super-ACO storage ring FEL with a monochromator and a double-sweep streak camera under various conditions of operation (detuning, 'CW' and Q-switched mode). From these data, it appears that the FEL is usually operated very close to the Fourier limit

  1. Towards the Fourier limit on the super-ACO Storage Ring FEL

    CERN Document Server

    Couprie, Marie Emmanuelle; Garzella, D; Hirsch, M; Moneron, G; Nutarelli, D; Renault, E; Roux, R; Thomas, C


    Systematic studies on the Free Electron Laser (FEL) line and micropulse have been performed on the Super-ACO storage ring FEL with a monochromator and a double-sweep streak camera under various conditions of operation (detuning, 'CW' and Q-switched mode). From these data, it appears that the FEL is usually operated very close to the Fourier limit.

  2. Refresher Course on Lasers and Applications in Chemical Processes

    Indian Academy of Sciences (India)

    lasers, modes of laser, mode locking, Q-switching, nonlinear optical materials, electro- optic and magneto-optic materials. It will also include laboratory demonstration experi- ments in selected areas of fluorescence and pump-probe methods. Teachers who wish to participate in the Refresher Course should submit their brief.

  3. Laser Surgeon, Client Education, and Satisfaction with Tattoo Removal

    DEFF Research Database (Denmark)

    Hutton Carlsen, Katrina; Esmann, Jørgen; Serup, Jørgen


    Studies of satisfaction with tattoo removal outcomes by laser, rated by clients themselves, including qualitative aspects, are sparse. We studied long-term results and client satisfaction with tattoo removal by Q-switched YAG laser. Client satisfaction is influenced by numerous factors: pretreatm...

  4. Reflectivity of transient Bragg reflection gratings in fiber laser with laser-wavelength selfsweeping

    Czech Academy of Sciences Publication Activity Database

    Peterka, Pavel; Honzátko, Pavel; Koška, Pavel; Todorov, Filip; Aubrecht, Jan; Podrazký, Ondřej; Kašík, Ivan


    Roč. 22, č. 24 (2014), s. 30024-30031 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GAP205/11/1840 Institutional support: RVO:67985882 Keywords : Ytterbium-doped fiber * Laser optics * Q switched lasers Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.488, year: 2014

  5. Reflectivity of transient Bragg reflection gratings in fiber laser with laser-wavelength self-sweeping: erratum

    Czech Academy of Sciences Publication Activity Database

    Peterka, Pavel; Honzátko, Pavel; Koška, Pavel; Todorov, Filip; Aubrecht, Jan; Podrazký, Ondřej; Kašík, Ivan


    Roč. 24, č. 14 (2016), s. 16222-16223 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GA16-13306S Institutional support: RVO:67985882 Keywords : Ytterbium-doped fiber * Laser optics * Q switched lasers Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.307, year: 2016

  6. New applications of surface plasmon resonance technology

    International Nuclear Information System (INIS)

    Zhang Tianhao; Yin Meirong; Fang Zheyu; Yang Haidong; Yang Jia; Yang Huizhan; Kang Huizhen; Yang Dapeng; Lu Yanzhen


    Surface plasmon resonance technology is reviewed and its new applications in various fields are described. These fields include surface plasmon resonance sensors, near-field scanning optical microscopy, thin film optics and thickness measurement, holography, precise measurement of angles, and Q switching. (authors)

  7. Power and energy scaling of a diode-end-pumped Nd:YLF laser through gain optimization

    CSIR Research Space (South Africa)

    Bollig, C


    Full Text Available An end-pumped Nd:YLF laser was demonstrated, which delivered 60.3 W continuous-wave and more than 52 W Q-switched average power for all repetition rates from 5 to 30 kHz. To achieve this, an analytical solution to estimate and optimize...

  8. Ruby laser for treatment of tattoos: technical considerations affecting clinical use (United States)

    Grove, Robert E.


    Recent clinical research on the use of ruby lasers for the treatment of tattoos and FIlk approval of a commercial system have renewed interest in this device. In this paper the principles of Q-switched ruby laser operation are reviewed, and potential sources of error in the estimation of delivered fluence are discussed.

  9. Laser induced damage threshold on metallic surfaces during laser cleaning

    CSIR Research Space (South Africa)

    Labuschagne, K


    Full Text Available laser paint removal. Laser induced damage on 316L stainless steel was studied, with the target subjected to single and multiple pulse irradiations using a Q-switched Nd:YAG, with fluences between 0.15 and 11.8 J/cm2. Several different damage morphologies...

  10. Millijoule Pulse Energy Second Harmonic Generation With Single-Stage Photonic Bandgap Rod Fiber Laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas Tanggaard


    In this paper, we demonstrate, for the first time, a single-stage Q-switched single-mode (SM) ytterbium-doped rod fiber laser delivering record breaking pulse energies at visible and UV light. We use a photonic bandgap rod fiber with a mode field diameter of 59μm based on a new distributed...

  11. RF Energy Compressor

    International Nuclear Information System (INIS)

    Farkas, Z.D.


    The RF Energy Compressor, REC described here, transforms cw rf into periodic pulses using an energy storage cavity, ESC, whose charging is controlled by 180 0 bi-phase modulation, PSK, and external Q switching, βs. Compression efficiency, C/sub e/, of 100% can be approached at any compression factor C/sub f/

  12. Generation of 13.9 µm radiation from CO2 by cascade lasing or ...

    Indian Academy of Sciences (India)

    the 1000 level is fast, and such lasers operate at low power and energies. ... CO2 laser; Q-switching; generation of 14 µm radiation from CO2; cascade lasing ... of 5% hole coupling output mirror, and a high reflectivity rotating mirror. This.

  13. Highly efficient deep ultraviolet generation by sum-frequency mixing ...

    Indian Academy of Sciences (India)

    Generation of deep ultraviolet radiation at 210 nm by Type-I third harmonic generation is achieved in a pair of BBO crystals with conversion efficiency as high as 36%. The fundamental source is the dye laser radiation pumped by the second harmonic of a Q-switched Nd : YAG laser. A walk-off compensated configuration ...

  14. Quasi-continuously pumped operation of 2.4% doped crystalline Nd:YAG in a bounce geometry (United States)

    Kubeček, Václav; Jelínek, Michal; Čech, Miroslav; Hiršl, Petr


    We report on efficient operation of highly doped 2.4 at. % crystalline Czochralski grown Nd:YAG at 1.06μm, 1.3μm and 1.4μm in a diode pumped bounce amplifier configuration under quasi-continuous pumping. At wavelength of 1064nm the linearly polarized pulses with energy of 16.8 mJ in free running regime with repetition rate of 10 Hz (optical to optical efficiency of 44.6 % and slope efficiency of 50%) and 1 mJ in passively Q-switched regime with pulse duration of 6.4 ns were generated.The passively Q switched operation at 1.3μm was also demonstrated.

  15. New and Advanced Picosecond Lasers for Tattoo Removal. (United States)

    Adatto, Maurice A; Amir, Ruthie; Bhawalkar, Jayant; Sierra, Rafael; Bankowski, Richard; Rozen, Doran; Dierickx, Christine; Lapidoth, Moshe


    Early methods of tattoo removal ultimately resulted in unacceptable cosmetic outcomes. While the introduction of laser technology was an improvement over the existing chemical, mechanical, and surgical procedures, the use of nonselective tattoo removal with carbon dioxide and argon lasers led to scarring. Q-switched lasers with nanosecond (10-9) pulse domains were considered to have revolutionized tattoo treatment, by selectively heating the tattoo particles, while reducing the adverse sequelae to adjacent normal skin. Theoretical considerations of restricting pulse duration, to heat tattoo particles to higher temperatures, proposed the use of sub-nanosecond pulses to target particles with thermal relaxation times lower than the nanosecond pulses in Q-switched lasers. Initial studies demonstrated that picosecond (10-12) pulses were more effective than nanosecond pulses in clearing black tattoos. Advances in picosecond technology led to the development of commercially available lasers, incorporating several different wavelengths, to further refine pigment targeting. © 2017 S. Karger AG, Basel.

  16. High-slope-efficiency 2.06 μm Ho: YLF laser in-band pumped by a fiber-coupled broadband diode. (United States)

    Ji, Encai; Liu, Qiang; Nie, Mingming; Cao, Xuezhe; Fu, Xing; Gong, Mali


    We first demonstrate the laser performance of a compact 2.06 μm Ho: YLF laser resonantly pumped by a broadband fiber-coupled diode. In continuous-wave (CW) operation, maximum output power of 1.63 W, corresponding to a slope efficiency of 89.2%, was obtained with a near diffraction-limited beam quality. In actively Q-switched operation, maximum pulse energy of 1.1 mJ was achieved at the repetition frequency of 100 Hz. The minimum pulse duration was 43 ns. The performance in both the CW and Q-switched regimes indicates that the current fiber-coupled diode in-band pumped Ho: YLF laser has great potential in certain conditions that require several watts of output power or several millijoules of short pulse energy.

  17. Photo-switch of pulsed Nd:YAG laser

    International Nuclear Information System (INIS)

    Ketta, W.W.J.


    In this work passive Q-switching and its effect on the output laser beam from a pulsed Nd:YAG laser was studied. This was achieved using the photochemically stable (BDNI) dye after dissolving it in dichloroethane. The absorption spectra of the dye solution and how suitable to use with Nd:YAG laser was also dealt with. Cooling unit for the laser system, a detector to detect the output pulse, and an electronic counter to measure the pulse duration were constructed. In the free-running regime, the divergence angle was measured. The form of the output, its energy, and how it is affected by the pumping energy were also studied. In the Q-switching regime, the relation between output and pumping energies was studied and compared to the same relation under the free-running regime. 5 tabs.; 33 figs.; 57 refs

  18. Laser drilling of superdeep micron holes in various materials with a programmable control of laser radiation parameters

    International Nuclear Information System (INIS)

    Basiev, Tasoltan T; Osiko, Vyacheslav V; Gavrilov, A V; Smetanin, S N; Fedin, A V


    The possibilities of enhancing the efficiency of laser drilling of micron holes, increasing their depth, and eliminating their conic shape are studied by using a single-mode loop Nd:YAG laser with self-phase conjugation on the gain gratings and passive Q-switching by a scanned gradiently coloured F 2 - :LiF crystal. Holes of diameters 15-150 μm and depth up to 20 mm with the aspect ratio (ratio of the hole depth to its diameter) of 50-155 are drilled in various metals and alloys. It is shown that passive Q-switch scanning during drilling provides the increase in the depth and speed of the laser drilling of superdeep holes by a factor of 1.5-2. (laser technologies)

  19. Theoretical and experimental study on the Nd:YAG/BaWO4/KTP yellow laser generating 8.3 W output power. (United States)

    Cong, Zhenhua; Zhang, Xingyu; Wang, Qingpu; Liu, Zhaojun; Chen, Xiaohan; Fan, Shuzhen; Zhang, Xiaolei; Zhang, Huaijin; Tao, Xutang; Li, Shutao


    A diode-side-pumped actively Q-switched intracavity frequency-doubled Nd:YAG/BaWO(4)/KTP Raman laser is studied experimentally and theoretically. Rate equations are used to analyze the Q-switched yellow laser by considering the transversal distributions of the intracavity photon density and the inversion population density. An 8.3 W 590 nm laser is obtained with a 125.8 W 808 nm pump power and a 15 kHz pulse repetition frequency. The corresponding optical conversion efficiency from diode laser to yellow laser is 6.57%, much higher than that of the former reported side-pumped yellow laser. The output powers with respect to the incident pump power are in agreement with the theoretical results on the whole.

  20. Self-transparency effects in heterogeneous nonlinear scattering media and their possible use in lasers

    International Nuclear Information System (INIS)

    Al'tshuler, G.B.; Ermolaev, V.S.; Krylov, K.I.; Manenkov, A.A.; Prokhorov, A.M.


    Transmission of intense laser beams through heterogeneous scattering media is considered. Effects of intensity limitation, self-recovery of the wave front of a transmitted beam, and bistable reflection associated with the laser-induced self-transparency (suppression of scattering) of such media are predicted because of the compensation of the linear refractive-index difference Δn/sub L/ of the heterocomponents of a medium by nonlinear change Δn/sub N//sub L/ for different mechanisms of nonlinearity. Applications of these effects in lasers for Q switching and mode locking are discussed. The observation of self-transparency effects in several heterogeneous media (glass particles in toluene and nitrobenzene, and lead molybdenite powder) for cw Ar- and pulsed Nd- and CO 2 -laser radiation is reported. Q switching and mode locking have also been demonstrated with a YAG:Nd laser using nonlinear scattering in a heterogeneous cell as a control element in a laser resonator

  1. Research on human skin laser damage thresholds. Final report, Nov 1971--Jun 1974

    Energy Technology Data Exchange (ETDEWEB)

    Rockwell, R.J. Jr.; Goldman, L.


    The report gives the results of a two-year study to determine the lowest radiant exposure levels at which the first observable reactions occur on human skin exposed to electromagnetic radiations emitted by normal mode and Q-switched ruby, Q-switched neodymium-glass, carbon dioxide, argon and neodymium-YAG laser devices. The principal goal of the study was to establish the 50 percent probability dose for such minimal reactions observed one-hour post-exposure. Such minimal radiant exposure levels are defined, for the purpose of this report, as the fifty percent probability dose for minimal reactions, and are designated as MRD50 (Minimal Reaction Dose, 50% probability). (GRA)

  2. NONLINEAR OPTICAL PHENOMENA Intracavity SRS conversion in diode-pumpedmultifunctional Nd3+:SrMoO4 laser crystal (United States)

    Basiev, Tasoltan T.; Smetanin, Sergei N.; Fedin, Aleksandr V.; Shurygin, Anton S.


    Lasing of a miniature all-solid-state SRS laser based on a Nd3+:SrMoO4 crystal with a LiF:F2--passive Q-switch is studied. The dependences of the laser and SRS self-conversion parameters on the initial transmission of the passive Q-switch are studied experimentally and theoretically. Simulation of the lasing kinetics has shown the possibility of nonlinear cavity dumping upon highly efficient SRS self-conversion of laser radiation. An increase in the active medium length from 1 to 3mm resulted in an increase in the energy of the output 1.17-μm SRS radiation from 20 μJ to record-high 60 μJ at the absorbed multimode diode pump energy of 3.7 mJ.

  3. Fabrication of Polycrystalline Transparent Co+2: MgAl2O4 by a Combination of Spark Plasma Sintering (SPS and Hot Isostatic Pressing (HIP Processes

    Directory of Open Access Journals (Sweden)

    Sokol Maxim


    Full Text Available Transparent Co2+ doped MgAl2Ob4 spinel was fabricated by SPS consolidation followed by and HIP treatment. It was established that HIP treatment significantly improved transparency of the ceramic in a wide range of wavelengths, especially, in a range, which is relevant for Q-switching. Nonlinear absorption was demonstrated and the ground and excited state absorption cross sections were estimated. The positive effect of the HIP treatment on the optical properties is related to an elimination of extremely fine porosity and to the location of Co ions at Mg2+sites in the spinel ionic structure. The experimental results indicate that the fabricated specimens can be used as a passive laser Q-switching material.

  4. Studies on Ytterbium-doped Fibre Laser Operating in Different Regimes

    International Nuclear Information System (INIS)

    Gan, Y; Xiang, W H; Zhang, G Z


    An ytterbium-doped fibre laser with a unidirectional ring cavity containing a polarizer placed between two in-line polarization controllers is presented. Depending on an equivalent saturable absorber, this laser operates in continuous, Q-switched mode-locked or CW mode-locked regimes. The passive method described here allowed us to choose the operating regime of the fibre laser by rotating the two polarization controllers and adjusting the pump power. Results of numerical simulations of pulse propagation in such a mode-locked fibre ring laser are presented, which reveals that the Q-switched mode-locked or CW modelocked regimes can be achieved by aligning the polarizer near the slow or the fast axes of the fibre

  5. Status of 2 micron laser technology program (United States)

    Storm, Mark


    The status of 2 micron lasers for windshear detection is described in viewgraph form Theoretical atmospheric and instrument system studies have demonstrated that the 2.1 micron Ho:YAG lasers can effectively measure wind speeds in both wet and dry conditions with accuracies of 1 m/sec. Two micron laser technology looks very promising in the near future, but several technical questions remain. The Ho:YAG laser would be small, compact, and efficient, requiring little or no maintenance. Since the Ho:YAG laser is laser diode pumped and has no moving part, the lifetime of this laser would be directly related to the diode laser lifetimes which can perform in excess of 10,000 hours. Efficiencies of 3 to 12 percent are expected, but laser demonstrations confirming the ability to Q-switch this laser are required. Coherent laser operation has been demonstrated for both the CW and Q-switched lasers.

  6. The use of laser beams for plasma diagnostics

    International Nuclear Information System (INIS)

    Gex, J.P.; Jolas, A.; Launspach, J.; Schirmann, D.


    The optical properties of lasers allow them to be a promising source for plasma diagnosis. The Q-switched lasers provide the opportunity to make observations in a very short time interval down to a few picoseconds. The laser space and time coherence properties allow interferometric measurements of plasma electron densities. Thus in the experiments of laser-matter interactions, the radiation obtained by frequency conversion of the Nd: glass laser emission is used for density measurements (up to 10 20 cm -3 ) in small scale plasmas (approximately equal to 1mm). Owing to the monochromaticity and high intensity of the Q-switched laser radiation, density fluctuations and microscopic instabilities of the plasma can be studied by Thompson scattering measurements. Finally, some statistically isotropic media become birefringent under the action of the strong electrical field of the laser beam radiation. This effect can be used for laser pulse duration measurements in a range not exceeding a few picoseconds [fr

  7. Random laser action in bovine semen (United States)

    Smuk, Andrei; Lazaro, Edgar; Olson, Leif P.; Lawandy, N. M.


    Experiments using bovine semen reveal that the addition of a high-gain water soluble dye results in random laser action when excited by a Q-switched, frequency doubled, Nd:Yag laser. The data shows that the linewidth collapse of the emission is correlated to the sperm count of the individual samples, potentially making this a rapid, low sample volume approach to count determination.

  8. Crystal growth, spectroscopic characterization and laser operation of Tm3+ and Ho3+ codoped LiLuF4 crystal (United States)

    Zhao, C. C.; Hang, Y.; Zhang, L. H.; He, X. M.; Yin, J. G.; Gong, J.; Yu, T.; Chen, W. B.


    Laser crystal Tm3+ and Ho3+ codoped LiLuF4 with high optical quality was grown by Czochralski technique. Its absorption and fluorescence spectra were investigated. A continuous wave output power of 1.12 W at 2066 nm was obtained with a slope efficiency of 24% by use of diode pumping. In the Q-switched mode, a slope efficiency of 18.9% and a maximum average power of 0.65 W were obtained.

  9. High accuracy 3-D laser radar

    DEFF Research Database (Denmark)

    Busck, Jens; Heiselberg, Henning


    We have developed a mono-static staring 3-D laser radar based on gated viewing with range accuracy below 1 m at 10 m and 1 cm at 100. We use a high sensitivity, fast, intensified CCD camera, and a Nd:Yag passively Q-switched 32.4 kHz pulsed green laser at 532 nm. The CCD has 752x582 pixels. Camera...

  10. Newer Trends in Laser Tattoo Removal (United States)

    Shah, Swapnil D; Aurangabadkar, Sanjeev J


    Q switched lasers are the current gold standard for laser tattoo removal. Though these systems are generally quite effective in clearing tattoos & have an established safety record, certain limitations exist while following the standard protocol. To overcome these limitation newer techniques such as multipass method, combination treatments with chemical agent and other laser have been introduced. These methods help in faster, less painful and complication free tattoo removal. PMID:25949019

  11. Investigation of micro-plasma in physiological saline produced by a high-power YAG laser

    International Nuclear Information System (INIS)

    Lu Jian; Ni Xiaowu; He Anzhi


    Micro-plasma and shock waves in the physiological saline produced by a Q-switched pulse YAG laser with nearby optical breakdown threshold energy are investigated by using optical shadowing exploring method, and a series of optical shadow graphs of micro-plasma and shock waves versus the incident laser energy and the delay time are obtained. Influence of mechanical action of shock waves for the high-power pulse laser on the ophthalmic treatment is discussed

  12. Diode-pumped Tm:YAP/YVO4 intracavity Raman laser

    International Nuclear Information System (INIS)

    Zhao, Jiaqun; Zhou, Xiaofeng; Wang, Guodong; Cheng, Ping; Xu, Feng


    The laser performance based on YVO 4 Raman conversion in a diode-pumped actively Q-switched Tm:YAP laser is demonstrated for the first time. With an incident diode power of 10.9 W and a pulse repetition rate of 1 kHz, the average output powers for the first Stokes laser at 2.4 μm is about 270 mW. (paper)

  13. The Geometric Theory of Roof Reflector Resonators (United States)


    reflector, if properly oriented, (The terms "roof-top prism ," "right-angle prism ," and - incorrectly - " Porro prism " are encountered in .the literature...Q-switch prisms ) in laser resonators have been infrequent compared to the attention given spherical mirrors. This chapter summarizes the relevant...designator (Refs 42 and 43). In one experiment, a 900 roof prism was tested in a resonator with a 70% reflecting filat mirror. Thus, in Fig. 2, the right roof

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

    International Nuclear Information System (INIS)

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


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

  15. Efficient diode-side-pumped Nd:YVO4 slab laser in different generation regimes

    International Nuclear Information System (INIS)

    Zinov'ev, A P; Antipov, Oleg L; Novikov, A A


    A diode-side-pumped Nd:YVO 4 slab laser with the grazing-incidence bounce geometry of the cavity is studied experimentally. Upon continuous pumping different lasing regimes are realised, namely, cw, passive and active Q-switching and passive mode-locking. The resonator parameters are optimised to achieve the maximum cw output power (∼17 W) and high-quality beam (M 2 ∼ 1.3). (lasers)

  16. Passive mode locking of 2.09 microm Cr,Tm,Ho:Y3Sc2Al3O12 laser using PbS quantum-dot-doped glass. (United States)

    Denisov, Igor A; Skoptsov, Nikolai A; Gaponenko, Maxim S; Malyarevich, Alexander M; Yumashev, Konstantin V; Lipovskii, Andrei A


    Passive Q-switched mode locking of a 2.09 microm flashlamp-pumped Cr(3+),Tm(3+),Ho(3+):Y(3)Sc(2)Al(3)O(12) laser by use of a phosphate glass doped with PbS quantum dots of 5 nm in radius was demonstrated. Mode-locked pulses of 290 ps in duration and up to 0.5 mJ in energy were registered.

  17. Control of ring lasers by means of coupled cavities

    DEFF Research Database (Denmark)

    Buchhave, Preben; Abitan, Haim; Tidemand-Lichtenberg, Peter


    Variable phase coupling to an external ring is used to control a unidirectional ring laser. The observed behavior of the coupled rings is explained theoretically. We have found experimentally that by quickly changing the phase of the feedback from the external ring it is possible to Q......-switch the ring laser. Also, at certain values of the phase of the feedback in the external ring, instabilities in the total system occur and oscillations arise in the ring laser....

  18. Dual wavelength operation in diode-end-pumped hybrid vanadate ...

    Indian Academy of Sciences (India)

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition ...

  19. Portable LIBS system for determining the composition of multilayer structures on objects of cultural value

    International Nuclear Information System (INIS)

    Moreira Osorio, Lesther; Ponce Cabrera, Luis V; Arronte Garcia, Miguel A; Flores Reyes, Teresa; Ravelo, Ivette


    This study presents the use of a portable Laser Induced Breakdown Spectroscopy (LIBS) prototype for determining the elemental composition of a metal jug. The system includes emission from a multiuse Q-switched Nd:YAG laser. By sampling at different points, the surface composition is determined. Furthermore, the presence of two layers of Pb and Cu and their thicknesses are determined through in-depth analysis.

  20. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)


    Feb 14, 2014 ... In this paper we report linearly polarized high average power passive Q-switched ytterbium-doped photonic crystal fibre laser with a Cr4+:YAG crystal as a saturable absorber. An average output power of 9.4 W with pulse duration of 64 ns and pulse repetition rate of 57.4 kHz with a slope efficiency of 52% ...

  1. Numerical calculations of the absorption and oscillation processes in the nonlinear polarized crystal Cr4+:YAG pumped by Nd-glass laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.


    A mathematical model describing the dynamic emission of intracavity isotropic Cr 4+ : YAG polarized solid-state saturable absorber as a tool of dual Q-switching and lasing processes 1.06 μm and 1.4 μm by double pumping pulse has been developed. This model describes the time evolution of interaction between the pumping laser pulse with a changed polarization state and the polarized absorber. (author)

  2. Successful treatment of laser induced hypopigmentation with narrowband ultraviolet B targeted phototherapy

    Directory of Open Access Journals (Sweden)

    Venkataram Mysore


    Full Text Available Q-switched 1064 nm neodymium-doped yttrium aluminium garnet (Qs 1064 nm Nd: YAG laser plays an important role in the treatment of pigmentary skin disorders, including tattoos. Although it has high efficacy and safety, adverse effect like hypopigmentation may occur causing anxiety to patients. We present a case report of Qs 1064 nm Nd: YAG laser induced hypopigmentation which was successfully treated with ultraviolet B targeted phototherapy, with rapid and satisfactory re-pigmentation.

  3. Newer trends in laser tattoo removal

    Directory of Open Access Journals (Sweden)

    Swapnil D Shah


    Full Text Available Q switched lasers are the current gold standard for laser tattoo removal. Though these systems are generally quite effective in clearing tattoos & have an established safety record, certain limitations exist while following the standard protocol. To overcome these limitation newer techniques such as multipass method, combination treatments with chemical agent and other laser have been introduced. These methods help in faster, less painful and complication free tattoo removal.

  4. Dither Cavity Length Controller with Iodine Locking

    Directory of Open Access Journals (Sweden)

    Lawson Marty


    Full Text Available A cavity length controller for a seeded Q-switched frequency doubled Nd:YAG laser is constructed. The cavity length controller uses a piezo-mirror dither voltage to find the optimum length for the seeded cavity. The piezo-mirror dither also dithers the optical frequency of the output pulse. [1]. This dither in optical frequency is then used to lock to an Iodine absorption line.

  5. Laser Trabeculoplasty Induces Changes in the Trabecular Meshwork Glycoproteome: A pilot study


    Amelinckx, Adriana; Castello, Maria; Arrieta-Quintero, Esdras; Lee, Tinthu; Salas, Nelson; Hernandez, Eleut; Lee, Richard K.; Bhattacharya, Sanjoy K.; Parel, Jean-Marie A


    Laser trabeculoplasty (LT) is a commonly used modality of treatment for glaucoma. The mechanism by which LT lowers the intraocular pressure (IOP) is unknown. Using cat eyes, selective laser trabeculoplasty (SLT) with a Q-switched frequency doubled Nd:YAG laser was used to treat the trabecular meshwork (TM). Laser treated TM was then subjected to proteomic analysis for detection of molecular changes and histological analysis for the detection of structural and protein expression patterns. In a...

  6. Jones matrix formulation of a Porro prism laser resonator with waveplates: theoretical and experimental analysis (United States)

    Agrawal, L.; Bhardwaj, A.; Pal, S.; Kumar, A.


    This article presents the results of a detailed theoretical and experimental analysis carried out on a folded Z-shaped polarization coupled, electro-optically Q-switched laser resonator with Porro prisms and waveplates. The advantages of adding waveplates in a Porro prism resonator have been explored for creating high loss condition prior to Q-switching and obtaining variable reflectivity with fixed orientation of Porro prism. Generalized expressions have been derived in terms of azimuth angles and phase shifts introduced by the polarizing elements. These expressions corroborate with known reported results under appropriate substitutions. A specific case of a crossed Porro prism diode-pumped Nd:YAG laser has been theoretically and experimentally investigated. In the feedback arm, a 0.57λ waveplate oriented at 135° completely compensates the phase shift of a fused silica Porro prism and provides better tolerances than a BK-7 prism/0.60λ waveplate combination to stop prelasing. The fused silica prism/0.57λ combination with waveplate at 112° acts like a 100% mirror and was utilized for optimization of free running performance. The effective reflectivity was determined for various orientations of the quarter waveplate in the gain arm to numerically estimate the Q-switched laser pulse parameters through rate equation analysis. Experimental results match well with the theoretical analysis.

  7. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

    CERN Document Server

    Yi, J H; Moon, H J; Rho, S P; Han, J M; Rhee, Y J; Lee, J M


    The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drast...

  8. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

    International Nuclear Information System (INIS)

    Yi, Jong Hoon; Kim, Jin Tae; Moon, Hee Jong; Rho, Si Pyo; Han, Jae Min; Rhee, Yong Joo; Lee, Jong Min


    The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drastically reduced pulse width

  9. Effects of various parameters of the 1064 nm Nd:YAG laser for the treatment of enlarged facial pores. (United States)

    Roh, Mi Ryung; Chung, Hye Jin; Chung, Kee Yang


    A variety of treatment modalities have been used to reduce the size of enlarged facial pores without obvious success. To assess and compare the effects of various parameters of a 1064 nm Nd:YAG laser in the treatment of enlarged facial pores. This was a prospective intra-individual left-right comparative study. A total of 40 individuals with enlarged facial pores were recruited for this study. Ten individuals were respectively treated on one half of the face with a quasi long-pulsed 1064 nm Nd:YAG laser (method 1), a Q-switched 1064 nm Nd:YAG laser (method 2), both quasi long-pulsed and Q-switched 1064 nm Nd:YAG lasers without carbon-suspended lotion (method 3), and both quasi long-pulsed and Q-switched 1064 nm Nd:YAG lasers with carbon-suspended lotion (method 4). The other half of the face was left untreated as a control. Five laser sessions were performed with a 3-week interval. The pore sizes were measured using an image analysis program and the sebum level was measured with a Sebumeter before and after the treatments. The pore size and sebum level decreased in all four methods on the treated side compared to the control (p pore size and sebum level.

  10. Hybrid Pulsed Nd:YAG Laser (United States)

    Miller, Sawyer; Trujillo, Skyler; Fort Lewis College Laser Group Team

    This work concerns the novel design of an inexpensive pulsed Nd:YAG laser, consisting of a hybrid Kerr Mode Lock (KLM) and Q-switch pulse. The two pulse generation systems work independently, non simultaneously of each other, thus generating the ability for the user to easily switch between ultra-short pulse widths or large energy density pulses. Traditionally, SF57 glass has been used as the Kerr medium. In this work, novel Kerr mode-locking mediums are being investigated including: tellurite compound glass (TeO2), carbon disulfide (CS2), and chalcogenide glass. These materials have a nonlinear index of refraction orders of magnitude,(n2), larger than SF57 glass. The Q-switched pulse will utilize a Pockels cell. As the two pulse generation systems cannot be operated simultaneously, the Pockels cell and Kerr medium are attached to kinematic mounts, allowing for quick interchange between systems. Pulse widths and repetition rates will vary between the two systems. A goal of 100 picosecond pulse widths are desired for the mode-locked system. A goal of 10 nanosecond pulse widths are desired for the Q-switch system, with a desired repetition rate of 50 Hz. As designed, the laser will be useful in imaging applications.

  11. Laser treatment of amateur tattoos in Arabs in Kuwait: effectiveness and safety. (United States)

    Qasem, Kholoud Darwish; Alotaibi, Mohammad Fehan


    Laser treatment of amateur tattoos on Fitzpatrick type V skin produces a considerable risk of complications because of the increased incidence of adverse pigmentary changes. The principle of selective photothermolysis predicts that the Q-switched alexandrite laser should be effective in removing tattoo ink with minimal side effects in patients with skin phototype V. To study the effectiveness of the Q-switched alexandrite (755 nm, 50 ns) laser in the treatment of amateur tattoos in Arabs in Kuwait. One hundred patients, each with multiple tattoos, were treated until total clearance. Fluences used ranged from 5 to 7 J/cm(2) with a spot size of 3 mm. Clinical evaluation was performed at baseline and at each follow-up visit until dyspigmentation resolved. Total clearing was observed in all tattoos after an average of six sessions. Both tattoo clearing and post-laser hypopigmentation (29%) and hyperpigmentation (38%) increased with higher fluences. In this prospective study, our findings suggest that the Q-switched alexandrite laser is an effective laser in removing amateur tattoos in patients with skin phototype V, but with a high incidence of pigmentary changes.

  12. Solid state pump lasers with high power and high repetition rate

    International Nuclear Information System (INIS)

    Oba, Masaki; Kato, Masaaki; Arisawa, Takashi


    We built a laser diode pumped solid state green laser (LDPSSGL) rated at high repetition rate. Two laser heads are placed in one cavity with a rotator in between to design to avoid thermal lensing and thermal birefringence effect. Although average green laser power higher than 10 W was obtained at 1 kHz repetition rate with pulse width of 20-30 nsec, the beam quality was so much deteriorated that energy efficiency was as low as 2 %. Learning from this experience that high power oscillator causes a lot of thermal distortion not only in the laser rod but also in the Q-switch device, we proceeded to built a oscillator/amplifier system. A low power oscillator has a slab type crystal in the cavity. As a result spatial distribution of laser power was extremely improved. As we expect that the high repetition rate solid state laser should be CW operated Q-switch type laser from the view point of lifetime of diode lasers, a conventional arc lamp pumped CW Q-switch green YAG laser of which the repetition rate is changeable from 1 kHz to 5 kHz and the pulse width is 250-570 nsec was also tested to obtain pumping characteristics of a dye laser as a function of power, pulse width etc., and dye laser pulse width of 100-130 nsec were obtained. (author)

  13. Sub-nanosecond lasers for cosmetics and dermatology (United States)

    Tarasov, Aleksandr A.; Chu, Hong


    We report about the development of two new subnanosecond solid-state laser models for application in dermatology and cosmetics. One model uses subnanosecond Nd: YAG microchip laser as a master oscillator and includes Nd: YAG double- and single-pass amplifiers. At 10 Hz this laser produces more than 600 mJ pulse energy with duration 500 +/- 5 ps. Another model (under development) is gain-switched Ti: Sapphire laser with short cavity. This laser produces 200 mJ, 560 ps pulses at 790 nm and uses standard Q-Switched Nd: YAG laser with nanosecond pulse duration as a pumping sourse.

  14. Development of a Low-Emission Spray Combustor for Emulsified Crude Oil (United States)


    ultraviolet (OH) and infrared (H2O) light wavelengths, but not in the visible. In simpler terms, it is invisible when it burns. UV or infrared imaging... lamp and Q-switch triggers as well as the Andor iStar CCD camera. 28 The synchronization of the lasers and camera was such that the pulse of each beam...combustion experiment and the associated electronic fuel control and safety systems. Dr. Tuttle mentored undergraduates and led the team of MS and PhD

  15. High-power planar dielectric waveguide lasers

    International Nuclear Information System (INIS)

    Shepherd, D.P.; Hettrick, S.J.; Li, C.; Mackenzie, J.I.; Beach, R.J.; Mitchell, S.C.; Meissner, H.E.


    The advantages and potential hazards of using a planar waveguide as the host in a high-power diode-pumped laser system are described. The techniques discussed include the use of proximity-coupled diodes, double-clad waveguides, unstable resonators, tapers, and integrated passive Q switches. Laser devices are described based on Yb 3+ -, Nd 3+ -, and Tm 3+ -doped YAG, and monolithic and highly compact waveguide lasers with outputs greater than 10 W are demonstrated. The prospects for scaling to the 100 W level and for further integration of devices for added functionality in a monolithic laser system are discussed. (author)

  16. Tungsten ditelluride for a nanosecond Ho,Pr:LiLuF4 laser at 2.95 µm (United States)

    Yan, Zhengyu; Li, Tao; Zhao, Jia; Zhao, Shengzhi; Yang, Kejian; Li, Guiqiu; Li, Dechun; Zhang, Shuaiyi; Li, Jian


    The linear and nonlinear absorption characteristics of a home-built multilayer tungsten ditelluride (WTe2) saturable absorber at ~3 µm were demonstrated for the first time. A passively Q-switched Ho,Pr:LiLuF4 laser was realized by inserting the WTe2-saturable absorber into a plane-concave laser cavity. A maximum average output power of 128 mW, with a pulse duration of 366 ns at a repetition rate of 92 kHz was obtained under an absorbed pump power of 3.67 W, corresponding to a pulse energy of 1.4 µJ.

  17. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments. (United States)

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok


    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG.

  18. Diode-pumped, single frequency Nd:YLF laser for 60-beam OMEGA laser pulse-shaping system

    International Nuclear Information System (INIS)

    Okishev, A.V.; Seka, W.


    The operational conditions of the OMEGA pulse-shaping system require an extremely reliable and low-maintenance master oscillator. The authors have developed a diode-pumped, single-frequency, pulsed Nd:YLF laser for this application. The laser generates Q-switched pulses of ∼160-ns duration and ∼10-microJ energy content at the 1,053-nm wavelength with low amplitude fluctuations (<0.6% rms) and low temporal jitter (<7 ns rms). Amplitude and frequency feedback stabilization systems have been used for high long-term amplitude and frequency stability

  19. Polishing Sapphire Substrates by 355 nm Ultraviolet Laser

    Directory of Open Access Journals (Sweden)

    X. Wei


    Full Text Available This paper tries to investigate a novel polishing technology with high efficiency and nice surface quality for sapphire crystal that has high hardness, wear resistance, and chemical stability. A Q-switched 355 nm ultraviolet laser with nanosecond pulses was set up and used to polish sapphire substrate in different conditions in this paper. Surface roughness Ra of polished sapphire was measured with surface profiler, and the surface topography was observed with scanning electronic microscope. The effects of processing parameters as laser energy, pulse repetition rate, scanning speed, incident angle, scanning patterns, and initial surface conditions on surface roughness were analyzed.

  20. A comparative study of the laser induce breakdown spectroscopy in single- and double-pulse laser geometry

    International Nuclear Information System (INIS)

    Sun Duixiong; Su Maogen; Dong Chenzhong; Wen Guanhong; Cao Xiangnian


    A time resolved laser induced breakdown spectroscopy technique (LIBS) was used for the investigation of emission signal enhancement on double-pulse LIBS. Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to generate laser-induced plasma on aluminium-based alloys. The plasma emission signals were recorded by spectrometer with ICCD detector. Spectral response calibration was performed by using deuterium and tungsten halogen lamps. Time evolution of the plasma temperature and electron density was investigated in SP and DP experiments. Based on the investigation of plasma parameters, the enhancements of emission line intensities were investigated, and the mechanisms of it were discussed. (author)

  1. Optimum output coupling for a mid-infrared KTiOAsO4 optical parametric oscillator

    International Nuclear Information System (INIS)

    Li, Guochao; Gao, Yesheng; Zheng, Guangjin; Zhao, Yao; Chen, Kunfeng; Wang, Qingpu; Bai, Fen


    Taking into account the turn off time of the Q-switch, the coupled equations for a mid-infrared KTiOAsO 4 optical parametric oscillator (OPO) are given. These rate equations are solved numerically and some key parameters for designing the laser system are determined. The key parameters include the optimal coupling and nonlinear crystal length which maximize the output power and OPO conversion efficiency. We found that a low-loss singly resonant OPO cavity not only enhances the mid-infrared output but also decreases the optimal OPO crystal length. (paper)

  2. Efficient high-peak-power and high-repetition-rate eye-safe laser using an intracavity KTP OPO

    International Nuclear Information System (INIS)

    Guo, J; Jiao, Z X; Wang, B; He, G Y


    An efficient high-peak-power and high-repetition-rate intracavity KTP optical parametric oscillator pumped by a Q-switched Nd:YVO 4 laser is demonstrated. We achieved 1.5 W output power of 1.5 μm at 10 kHz repetition rate with the pulse duration of 6 ns. The maximum peak power of 25 kW and the maximum pulse energy of 150 μJ have been obtained. The maximum conversion efficiency of 9.5% is achieved with respect to a laser diode power of 10.5 W. (paper)

  3. Advanced solar energy conversion. [solar pumped gas lasers (United States)

    Lee, J. H.


    An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.

  4. An improved prism for use in laser resonators (United States)

    Richards, J.


    The use of compound total internal reflection prisms rather than Porro prisms in polarisation coupled lasers is proposed. Performance advantages resulting from the use of these prisms include higher output without the need to bias the Pockels cell, ability to give a larger range of output coupling and independence of performance on the refractive index of the prism. In conventional Q-switched lasers the use of the prism at the Pockels cell end of the resonator instead of the usual 100% reflecting mirror also leads to some advantages including better hold-off, elimination of the need to bias the Pockels cell and insensitivity in one plane to angular misalignment.

  5. Advanced Solid-State Lasers/Compact Blue-Green Lasers. 1993 Technical Digest Series. Volume 2. Organization of the 1993 Photonics Science Topical Meetings held in New Orleans, Louisiana on 1 - 4 February 1993 (United States)


    in the Q-switch arm Porro prism . The waveplate prism pair rotate the polarization 90" in a double pass creating a low Q resonator . 1/4 X voltage...of the head was enough to distort the mode. The beam quality was regained above 70 Hz when the birefringence was compensated with a porro prism (Figure...lA.); in this configuration, the laser could be run up to the 100 Hz limit of the diodes. In this porro prism cavity, output was 53 mJ and was

  6. The Construction and Calibration of a LADAR (Laser Detection and Ranging) Cross-Section Measurement Range (United States)


    resonator optics consist of two porro prisms which are oriented 900 from one another about the cavity’s optical axis. In other words, the roof edges of each... prism are perpendicular to one another. The Nd:YAG laser rod measures 5 mm in diameter by 75 mm long and is optically pumped by a Xenon flashlamp. Q...Switching of the laser is performed by a Pockels Cell. A dielectric polarizer is sealed between two right angle prisms which are joined symetrically

  7. Analytical capabilities of laser-probe mass spectrometry

    International Nuclear Information System (INIS)

    Kovalev, I.D.; Madsimov, G.A.; Suchkov, A.I.; Larin, N.V.


    The physical bases and quantitative analytical procedures of laser-probe mass spectrometry are considered in this review. A comparison is made of the capabilities of static and dynamic mass spectrometers. Techniques are studied for improving the analytical characteristics of laser-probe mass spectrometers. The advantages, for quantitative analysis, of the Q-switched mode over the normal pulse mode for lasers are: (a) the possibility of analysing metals, semiconductors and insulators without the use of standards; and (b) the possibility of layer-by-layer and local analysis. (Auth.)

  8. Self-stabilization of a mode-locked femtosecond fiber laser using a photonic bandgap fiber

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry


    We demonstrate a self-stabilization mechanism of a semiconductor saturable absorber mode-locked linearcavity Yb-doped fiber laser using an intracavity photonic bandgap fiber. This mechanism relies on the spectral shift of the laser pulses to a spectral range of higher anomalous dispersion...... and higher loss of the photonic bandgap fiber, as a reaction to the intracavity power buildup. This, in particular, results in a smaller cavity loss for the stably mode-locked laser, as opposed to the Q-switched mode-locking scenario. The laser provides stable 39–49 pJ pulses of around 230 fs duration at 29...

  9. Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper


    . The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse......We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror...

  10. Development of frequency tunable Ti:sapphire laser and dye laser pumped by a pulsed Nd:YAG laser

    International Nuclear Information System (INIS)

    Yi, Jong Hoon; Horn, Roland; Wendt, K.


    We investigated lasing characteristics of two kinds of tunable laser, liquid dye laser and solid Ti:sapphire crystal laser, pumped by high pulse repetition rate Nd:YAG laser. Dye laser showed drastically reduced pulsewidth compared with that of pump laser and it also contained large amount of amplified spontaneous emission. Ti:sapphire laser showed also reduced pulsewidth. But, the laser conversion pump laser and Ti:sapphire laser pulse, we used a Brewster-cut Pockel's cell for Q-switching. The laser was frequency doubled by a type I BBO crystal outside of the cavity.

  11. Quantum Nonlinear Optics

    CERN Document Server

    Hanamura, Eiichi; Yamanaka, Akio


    This graduate-level textbook gives an introductory overview of the fundamentals of quantum nonlinear optics. Based on the quantum theory of radiation, Quantum Nonlinear Optics incorporates the exciting developments in novel nonlinear responses of materials (plus laser oscillation and superradiance) developed over the past decade. It deals with the organization of radiation field, interaction between electronic system and radiation field, statistics of light, mutual manipulation of light and matter, laser oscillation, dynamics of light, nonlinear optical response, and nonlinear spectroscopy, as well as ultrashort and ultrastrong laser pulse. Also considered are Q-switching, mode locking and pulse compression. Experimental and theoretical aspects are intertwined throughout.

  12. Laser inactivation of periodontal bacteria using photosensitizing dyes (United States)

    Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.


    We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

  13. Laser Processing on the Surface of Niobium Superconducting Radio-Frequency Accelerator Cavities (United States)

    Singaravelu, Senthilraja; Klopf, Michael; Krafft, Geoffrey; Kelley, Michael


    Superconducting Radio frequency (SRF) niobium cavities are at the heart of an increasing number of particle accelerators.~ Their performance is dominated by a several nm thick layer at the interior surface. ~Maximizing its smoothness is found to be critical and aggressive chemical treatments are employed to this end.~ We describe laser-induced surface melting as an alternative ``greener'' approach.~ Modeling guided selection of parameters for irradiation with a Q-switched Nd:YAG laser.~ The resulting topography was examined by SEM, AFM and Stylus Profilometry.

  14. Raman spectroscopy measurement of CH4 gas and CH4 dissolved in water for laser remote sensing in water (United States)

    Somekawa, Toshihiro; Fujita, Masayuki


    We examined the applicability of Raman spectroscopy as a laser remote sensing tool for monitoring CH4 in water. The Raman technique has already been used successfully for measurements of CO2 gas in water. In this paper, considering the spectral transmittance of water, third harmonics of Q-switched Nd:YAG laser at 355 nm (UV region) was used for detection of CH4 Raman signals. The Raman signal at 2892 cm-1 from CH4 dissolved in water was detected at a tail of water Raman signal.

  15. Investigation of local thermodynamic equilibrium of laser induced Al2O3–TiC plasma in argon by spatially resolved optical emission spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Alnama


    Full Text Available Plasma plume of Al2O3–TiC is generated by third harmonic Q-switched Nd:YAG nanosecond laser. It is characterized using Optical Emission Spectroscopy (OES at different argon background gas pressures 10, 102, 103, 104 and 105 Pa. Spatial evolution of excitation and ionic temperatures is deduced from spectral data analysis. Temporal evolution of Ti I emission originated from different energy states is probed. The correlation between the temporal behavior and the spatial temperature evolution are investigated under LTE condition for the possibility to use the temporal profile of Ti I emission as an indicator for LTE validity in the plasma.

  16. A SESAM passively mode-locked fiber laser with a long cavity including a band pass filter

    International Nuclear Information System (INIS)

    Song, Rui; Chen, Hong-Wei; Chen, Sheng-Ping; Hou, Jing; Lu, Qi-Sheng


    A semiconductor saturable absorber mirror (SESAM) passively mode-locked fiber laser with a long cavity length over 700 m is demonstrated. A band pass filter is inserted into the laser cavity to stabilize the lasing wavelength. Some interesting phenomena are observed and discussed. The central wavelength, repetition rate, average power and single pulse energy of the laser are 1064 nm, 281.5 kHz, 11 mW and 39 nJ, respectively. The laser operates stably without Q-switching instabilities, which greatly reduces the damage opportunities of the SESAM

  17. Optical Production and Detection of Ultrasonic Waves in Metals for Nondestructive Testing (United States)

    Morrison, R. A.


    Ultrasonic waves were produced by striking the surface of a metal with the focused one-joule pulse of a Q-switched ruby laser. Rayleigh (surface) waves and longitudinal waves were detected with conventional transducers. Optical methods of detection were tested and developed. Rayleigh waves were produced with an oscillator and transducer. They were optically detected on curved polished surfaces, and on unpolished surfaces. The technique uses a knife edge to detect small angle changes of the surface as the wave pulse passes the illuminated spot. Optical flaw detection using pulse echo and attenuation is demonstrated.

  18. Efficient 1.9-μm Raman generation in a hydrogen-filled hollow-core fibre

    Energy Technology Data Exchange (ETDEWEB)

    Gladyshev, A V; Kolyadin, A N; Kosolapov, A F; Yatsenko, Yu P; Pryamikov, A D; Biryukov, A S; Bufetov, I A; Dianov, E M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)


    Efficient Raman generation in a molecular hydrogenfilled hollow-core fibre having a cladding in the form of a single ring of capillaries has been demonstrated for the first time. The pump source used was a Q-switched Nd:YAG laser with a pulse duration of 125 ns, and a single-pass (cavity-free) configuration was employed. The maximum average output power at 1.9 μm was 300 mW, and the differential quantum efficiency was 87%, a record level for such experiments. (lasers)

  19. Phase-matched light amplification by three-wave mixing process in a birefringent fiber due to externally applied stress

    International Nuclear Information System (INIS)

    Ohashi, M.; Kitayama, K.; Ishida, Y.; Uchida, N.


    A novel method to achieve phase-matched light amplification in a birefringent fiber via the three-wave mixing is proposed by using frequency shift change due to the stress applied to the fiber. It is confirmed that the signal power from a cw laser diode at lambda = 1.292 μm is amplified by 6.1 x 10 3 times in the birefringent fiber pumped with a Q-switched Nd: yttrium aluminum garnet laser at lambda = 1.064 μm. This will provide a new fiber-optic light signal amplifier having a good tolerance for variation of signal wavelengths

  20. Viability study of using the Laser-Induced Breakdown Spectroscopy technique for radioactive waste detection at IPEN-CNEN/SP, Brazil

    International Nuclear Information System (INIS)

    Tunes, Matheus A.; Schon, Claudio G.


    this work a viability study to apply the Laser-Induced Breakdown Spectroscopy (LIBS) technique for radioactive waste characterization was developed using a high power q-switched Nd:YAG rod-Laser, operating at 1064 nm with 9 ns of pulse-width and pulse-to-pulse energy around 10 to 20 mJ. When applied in a non-radioactive deionized water sample, our methodology exhibits a good potential to spectroscopy detection of Hydrogen species with resolution around 0.035 nm at full width at half maximum (FWHM). (author)

  1. Model and experimental investigation of frequency conversion in AgGaGexS2(1+x) (x = 0, 1) crystals

    International Nuclear Information System (INIS)

    Wang Tiejun; Kang Zhihui; Zhang Hongzhi; Feng Zhishu; Jiang Yun; Gao Jinyue; Andreev, Yury M; Lanskii, Gregory V; Shaiduko, Anna V


    Analysis of available and developed data on phase matching in AgGaGe x S 2(1+x) (x = 0, 1) crystals is carried out. Nanosecond AgGaS 2 type I optical parametric oscillator with a continuously tunable range 2.65-5.29 μm is demonstrated pumped by a Q-switched Nd : YAG laser. An output pulse energy of up to 0.56 mJ at 4 μm is recorded. Phase matching of second harmonic generation in both crystals is represented. Best sets of Sellmeier equations for two crystals are determined

  2. Spectroscopic analysis of coal plasma emission produced by laser ablation


    Vera-Londoño, Liliana Patricia; Pérez-Taborda, Jaime Andrés; Riascos-Landázuri, Henry


    An analysis of plasma produced by laser ablation using 1,064 nm of laser radiation from a Q-switched Nd:YAG on coal mineral samples under air ambient, was performed. The emission of molecular band systems such as C2 Swan System , the First Negative System N2 (Band head at 501.53 nm) and different emission lines were investigated using the optical emission spectroscopy technique. The C2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0.62 eV). The density and ...

  3. Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji


    A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

  4. Laser-prearc railgun: Development for the application to a fuel pellet injector of a nuclear fusion reactor (United States)

    Tamura, H.; Sawaoka, A. B.; Oda, Y.; Onozuka, M.; Kuribayashi, S.; Shimizu, K.


    The laser-prearc railgun, that utilizes the phenomenon of laser-induced arc formation, was constructed and tested with plastic pellet projectiles. We envision our railgun as especially well suited as a solid hydrogen pellet injector for magnetic confinement fusion. The system consisted of a gas gun for preacceleration of a pellet and a railgun for its primary acceleration. A Q-switched ruby laser was used to induce electrical breakdown of propellant helium gas behind a dielectric pellet in the railgun. The present railgun was shown to accelerate a plastic pellet up to a velocity of 2.4 km/s.

  5. Fiber-based broadband black-light source


    Sylvestre , Thibaut; Lee , Min Won; Ragueh , A. R.; Stiller , Birgit; Fanjoux , Gil; Barviau , B.; Mussot , A.; Kudlinski , A.


    International audience; Black-Light or Wood's lamp refers to sources that emit long-wavelength ultraviolet radiation (UV-A) from 315 nm and little visible light till 410 nm (blue). In this paper, we present a new fibre-based source of "black light", a source that emits broadband ultraviolet radiation but only small amounts of visible light and no infrared light. We made this source by pumping a specially designed silica photonic crystal fibre (PCF) with 355 nm light pulses from a Q-switched f...

  6. Four-wave-mixing and nonlinear cavity dumping of 280 picosecond 2nd Stokes pulse at 1.3 μm from Nd:SrMoO4 self-Raman laser

    International Nuclear Information System (INIS)

    Smetanin, S N; Ivleva, L I; Jelínek, M Jr; Kubeček, V; Jelínková, H; Shurygin, A S


    The 280 picosecond 2nd Stokes Raman pulses at 1.3 μm were generated directly from the miniature diode-pumped Nd:SrMoO 4 self-Raman laser. Using the 90° phase matching insensitive to the angular mismatch, the self-Raman laser allowed for the achievement of the four-wave-mixing generation of the 2nd Stokes Raman pulse directly in the active Nd:SrMoO 4 crystal at stimulated Raman scattering (SRS) self-conversion of the laser radiation. The passive Cr:YAG Q-switching and nonlinear cavity dumping was used without any phase locking device. (letter)

  7. LD end pumped mode locked and cavity dumped Nd:YAP laser at 1.34 μm (United States)

    Wang, X.; Wang, S.; Rhee, H.; Eichler, H. J.; Meister, S.


    We report a LD end pumped actively mode locked, passively Q switched and cavity dumped Nd:YAP laser at 1.34 μm. The dumped output pulse energy of 160 μJ is obtained at a repetition rate of 10 Hz. Passing through a LD end pumped, double-passed Nd:YAP amplifier the pulse energy is amplified to 1.44 mJ. The corresponding amplification factor is 9. Stimulated Raman scattering experiment is taken with a 9 mm long PbWO4 Raman crystal. Maximum of 20% Raman conversion is reached.

  8. All-fiber polarization switch (United States)

    Knape, Harald; Margulis, Walter


    We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

  9. Developing Topological Insulator Fiber Based Photon Pairs Source for Ultrafast Optoelectronic Applications (United States)


    of a thin layer of topological insulator Bi2Se3 with the transmission of T = 50%. We apply magnetic field B=3 tesla normal to the sample and parallel...nonlinear induced by magnetic field in the Topological Insulator Bi2Se3 and Molybdenum Disulfide MoS2. The nonlinear effect is pulse broadening...Topological Insulator Q- Switched Erbium-Doped Fiber Laser”, IEEE J. Sel. Top. Quant. Electron., 20, 0900508 (2014). [2]. Shuqing Chen et al, “Stable Q

  10. Le laser comme moyen de dégagement de produits de corrosion sur un objet archéologique : le cas de la dorure sur alliage cuivreux.

    Directory of Open Access Journals (Sweden)

    Valentine Brodard


    Full Text Available Le dégagement des produits de corrosion présents sur les objets archéologiques en alliage cuivreux dorés comporte d’importants risques d’altération. Lors d’un dégagement mécanique se pose le problème de la rayure de la surface dorée. Lors d’un traitement chimique, une accélération des processus de corrosion des alliages en présence risque de se produire.Dans ce travail, nous avons testé l’utilisation du laser comme méthode alternative de dégagement des produits de corrosion sur ce type d’objets. Trois lasers Nd:YAG ont été utilisés lors de cette étude : un laser Short free running, un laser long Q-switch et un laser Q-switch. Les tests ont été effectués sur des coupons en cuivre dorés fabriqués d’après deux masques précolombiens. Nos résultats montrent que ces lasers ne permettent pas un dégagement des produits de corrosion sans altérer la surface dorée. Par contre, il existe la possibilité de tester des lasers offrant une vitesse d’impulsion plus rapide comme le laser femtoseconde.The removal of corrosion products from archaeological gilded copper alloys lead to high risks of damage. A mechanical cleaning may induce abrasions of the gilding when a chemical cleaning might increase the corrosion processes.In this thesis, we have tested the use of laser as an alternative for the removal of corrosion products on gilded copper alloy. Three lasers Nd:YAG  were used during our tests : a laser Short free running, a laser Long Q-switch and a laser Q-switch. The tests have been done on gilded copper samples prepared after two pre-Columbian masks. The results prove that lasers don’t permit the removal of corrosion products without damage on the gilded surface. However a laser with a faster pulse like a femtosecond laser may allow the cleaning of gilded copper without any damage

  11. Bullet Design and Fabrication of Dual Mode Pyroelectric Sensor: High Sensitive Energymeter for Nd: YAG Laser and Detector for Chopped He-Ne Laser

    Directory of Open Access Journals (Sweden)



    Full Text Available Pyroelectric sensor using TGS has been designed and fabricated which can be operated in laser energy meter mode as well as pyroelectric detector mode. The amplifying circuit configuration has very good signal to noise ratio, very high input impedance and low drift. The pyroelectric sensor has been tested using Q-switched Nd: YAG laser and chopped He-Ne laser. The sensitivity of pyroelectric sensor in energymeter mode is 421.7V/J and the voltage responsivity of the pyroelectric sensor is 3.27 V/W in detector mode.

  12. Laboratory for Laser Energetics annual report, 1 October 1984-30 September 1985

    International Nuclear Information System (INIS)


    Overviews of the GDL and OMEGA facilities are given. The retrofit of the GDL with liquid crystal polarizers is described. Synchronization of the actively mode-locked and actively Q-switched oscillators is described. Progress in laser fusion includes a theory of electron heat transport, sputter-coating of laser targets, absorption line measurement of the tamper, x-ray conversion for high-Z targets, mass ablation in uv-irradiated targets, uv target designs, stimulated Raman scattering in a collisional homogeneous plasma, and absorption spectroscopy as a diagnostic. 267 refs., 134 figs., 113 tabs

  13. MLRS - A lunar/artificial satellite laser ranging facility at the McDonald Observatory (United States)

    Shelus, P. J.


    Experience from lunar and satellite laser ranging experiments carried out at McDonald Observatory has been used to design the McDonald Laser Ranging Station (MLRS). The MLRS is a dual-purpose installation designed to obtain observations from the LAGEOS satellite and lunar targets. The instruments used at the station include a telescope assembly 0.76 meters in diameter; a Q-switched doubled neodymium YAG laser with a pulse rate of three nanoseconds; and a GaAs photodetector with Fabry-Perot interferometric filter. A functional diagram of the system is provided. The operating parameters of the instruments are summarized in a table.

  14. Laser-fabricated castor oil-capped silver nanoparticles. (United States)

    Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir


    Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.

  15. Synthesis and Properties of Platinum Nanoparticles by Pulsed Laser Ablation in Liquid

    Directory of Open Access Journals (Sweden)

    Maria Isabel Mendivil Palma


    Full Text Available Platinum (Pt nanoparticles were synthesized by pulsed laser ablation in liquid (PLAL technique in different liquids (acetone, ethanol, and methanol. Ablation was performed using a Q-switched Nd:YAG laser with output energy of 230 mJ/pulse for 532 nm wavelength. Ablation time and laser energy fluence were varied for all the liquids. Effects of laser energy fluence, ablation time, and nature of the liquid were reported. The mean size, size distributions, shape, elemental composition, and optical properties of Pt nanoparticles synthesized by PLAL were examined by transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and UV-Visible absorption spectroscopy.

  16. Utilizing Laser-Induced Breakdown Spectroscopy Method to recognize chemical composition of low-carbon steel in NH3(NO)4 material (United States)

    Saud Oraibi, Nissan


    A standoff laser Induced Break down Spectroscopy (L.I.B.S) technique has been used to characterization the organic material such as NH3(NO)4, a Q-switched Nd:YAG laser (1064 nm wavelength, 9 ns pulse width and 1 Hz repetition rate, 300 mJ is focused to the targets to generate plasma. HR 4000 CG-UV-NIR spectrum analyzer was used to collect the generated plasma emissions, specific signature of each targets material can be obtained by analysis the plasma emission spectrum Peak ratio analysis technique is used for the identification of energetic materials.

  17. BN-based nano-composites obtained by pulsed laser deposition

    International Nuclear Information System (INIS)

    Major, B.; Kosydar, R.; Major, L; Mroz, W.; Burdynska, S.; Jelinek, M.; Kot, M.; Kustosz, R.


    Boron nitride thin layers were produced by means of the pulsed laser deposition technique from hexagonal boron nitride target. Two types of laser i.e. Nd: YAG with Q-switch as well as KrF coupled with RF generator were used. Influence of deposition parameters on surface morphology, phase composition as well as mechanical properties is discussed. Results obtained using Fourier Transformed Infrared Spectroscopy, Transmission and Scanning Electron Microscopy, Atomic Force Microscopy are presented. Micromechanical properties measured during micro indentation, scratch and wear tests are also shown. (authors)

  18. Laser technology for high precision satellite tracking (United States)

    Plotkin, H. H.


    Fixed and mobile laser ranging stations have been developed to track satellites equipped with retro-reflector arrays. These have operated consistently at data rates of once per second with range precision better than 50 cm, using Q-switched ruby lasers with pulse durations of 20 to 40 nanoseconds. Improvements are being incorporated to improve the precision to 10 cm, and to permit ranging to more distant satellites. These include improved reflector array designs, processing and analysis of the received reflection pulses, and use of sub-nanosecond pulse duration lasers.

  19. Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

    Directory of Open Access Journals (Sweden)

    Schwemmer G.


    Full Text Available We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

  20. Energy-beam processing studies on Ta/U and Ir/Ta systems

    International Nuclear Information System (INIS)

    Kaufmann, E.N.; Peercy, P.S.; Jacobson, D.C.; Draper, C.W.; Huegel, F.J.; Echer, C.J.; Makowiecki, D.M.; Balser, J.D.


    Films of Ta metal on uranium and of Ir metal on tantalum have been irradiated and melted by pulses from Q-switched Ruby and frequency-doubled Nd:YAG lasers to investigate the nature of the resulting mixtures in light of the very different binary-phase diagrams of the two systems. In addition, a two-phase Ir-Ta alloy has been surface-processed with CW CO 2 -laser radiation and with an electron beam in order to study microstructure refinement and test the advantage of using alloys as opposed to film-on-substrate combinations for the development of claddings

  1. Cavity enhanced rephased amplified spontaneous emission

    International Nuclear Information System (INIS)

    A Williamson, Lewis; J Longdell, Jevon


    Amplified spontaneous emission is usually treated as an incoherent noise process. Recent theoretical and experimental work using rephasing optical pulses has shown that rephased amplified spontaneous emission (RASE) is a potential source of wide bandwidth time-delayed entanglement. Due to poor echo efficiency the plain RASE protocol does not in theory achieve perfect entanglement. Experiments done to date show a very small amount of entanglement at best. Here we show that RASE can, in principle, produce perfect multimode time-delayed two mode squeezing when the active medium is placed inside a Q-switched cavity. (paper)

  2. Upconversion Properties of the Er-Doped Y2O3, Bi2O3 and Sb2O3 Nanoparticles Fabricated by Pulsed Laser Ablation in Liquid Media

    International Nuclear Information System (INIS)

    Zamiri Reza; Bahari-Poor Hamid-Reza; Zakaria Azmi; Jorfi Raheleh; Zamiri Golnoush; Rebelo Avito; Omar Akrajas Ali


    Er-doped Y 2 O 3 , Bi 2 O 3 and Sb 2 O 3 nanoparticles are synthesized using pulsed laser ablation in a liquid. Ceramic targets of Y 2 O 3 :Er 3+ , Bi 2 O 3 :Er 3+ and Sb 2 O 3 :Er 3+ for ablation process are prepared by standard solid-state reaction technique and ablation is carried out in 5-ml distilled water using nanosecond Q-switched Nd:YAG laser. The morphology and size of the fabricated nanoparticles are evaluated by transmission electron microscopy and the luminescence emission properties of the prepared samples are investigated under different excitation wavelengths

  3. Ion acceleration with a narrow energy spectrum by nanosecond laser-irradiation of solid target

    Energy Technology Data Exchange (ETDEWEB)

    Altana, C., E-mail: [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lanzalone, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore,” Via delle Olimpiadi, 94100 Enna (Italy); Mascali, D.; Cirrone, G. A. P.; Schillaci, F.; Tudisco, S. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Muoio, A. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F. D’Alcontres 31, 98166 Messina (Italy)


    In laser-driven plasma, ion acceleration of aluminum with the production of a quasi-monoenergetic beam has occurred. A useful device to analyze the ions is the Thomson parabolas spectrometer, a well-known diagnostic that is able to obtain information on charge-to-mass ratio and energy distribution of the charged particles. At the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS in Catania, experimental measures were carried out; the features of LENS are: Q-switched Nd:YAG laser with 2 J laser energy, 1064 nm fundamental wavelengths, and 6 ns pulse duration.

  4. Laser Decontamination of Surfaces Contaminated with Cs+ Ion

    International Nuclear Information System (INIS)

    Baigalmaaa, B.; Won, H. J.; Moon, J. K.; Jung, C. H.; Lee, K. W.; Hyun, J. H.


    Laser decontamination technology has been proven to be an efficient method for a surface modification of metals and concretes contaminated with radioactive isotopes. Furthermore, the generation of a secondary waste is negligible. The radioactivity of hot cells in the DFDF (Dupic Fuel Development Facility) is presumed to be very high and the predominant radionuclide is Cs-137. A series of laser decontamination studies by a fabricated Q-switched Nd:YAG laser system were performed on stainless steel specimens artificially contaminated with Cs+ ion. Decontamination characteristics of the stainless steel were analyzed by SEM and EPMA

  5. Laser ignition of traumatically embedded firework debris. (United States)

    Taylor, C R


    The Q-switched ruby laser (QSRL) has a good track record for traumatic tattoo removal. An unusual case of QSRL-treatment of a traumatic tattoo composed of firework debris is presented. A young man's traumatic tattoo, composed of firework debris, underwent QSRL ablation at 4-7 J/cm2 (pulse width 5 mm; duration 20 ns). Each test pulse produced visible sparks and focal projectile ejection of skin with pox-like scar formation. Caution is advised when using the QSRL for the treatment of traumatic tattoos composed of potentially combustible debris.

  6. Eye safe laser range finders

    International Nuclear Information System (INIS)

    Snir, M.; Margaliot, M.; Amitzi, A.


    During the 1970's, Ruby (Q switched) laser based range finders with a wavelength of 694nm were first used. These lasers operated in a pulse mode within the visible light range and produced a risk for the eye retina. The laser beam striking the macula could damage the eye and might cause blindness. Over the years, Nd:YAG (Q switched) lasers were developed (operating at 1064nm) for range finding and designation uses. The wavelength of these lasers, operating in the near Infra-Red range (invisible), is also focused tightly on the retina. The human eye does not respond to the invisible light so there is no natural protection (eye blink reflex) as in the visible light. The operation of these lasers worldwide, especially when the laser beam is exposed, causes occasional eye accidents. Another risk is stemming from the use of observation systems with a high optical gain, in the laser operation areas, which enlarge the range of risk quite significantly. Therefore, research and development efforts were invested in order to introduce eye safe lasers. One of the solutions for this problem is presented in following document

  7. Thermal lens measurements in the cornea. (United States)

    Venkatesh, S; Guthrie, S; Cruickshank, F R; Bailey, R T; Foulds, W S; Lee, W R


    Q-switched pulses from a neodymium/YAG (yttrium-aluminium-garnet) laser were passed through corneal discs taken from the enucleated eyes of three baboons and four rabbits. The time course of heat dissipation following absorption of laser energy by the tissue was studied with the use of a second continuous wave laser beam acting as a probe. It was found that the absorption of each neodymium/YAG pulse created a transient divergent lens within the cornea as theoretical considerations predicted. The relaxation time that characterised the decay of this thermal lens for a 1/e laser beam diameter of 2.0 mm was found to be 2.3 +/- 0.1 s (mean +/- standard error for 12 separate groups of measurements). Our results show that Q-switched laser pulses passing through apparently unaffected transparent tissues can induce thermal lens effects which persist for several seconds. The optical transfer of each pulse in a stream will be identical only if enough time is left between pulses for the tissues to return to their initial state. Therefore, when such laser pulses sharply focused to perform high precision intraocular surgery are used, thermal lensing in the transparent ocular media must limit the rate at which pulses can be usefully delivered.

  8. Diode-pumped efficient laser operation and spectroscopy of Tm,Ho:YVO 4 (United States)

    Li, G.; Yao, B. Q.; Meng, P. B.; Duan, X. M.; Ju, Y. L.; Wang, Y. Z.


    Spectroscopic characterization of co-doped Tm,Ho:YVO 4 crystal grown by the Czochralski method has been performed including absorption spectrum, emitting spectrum and luminescence decay lifetime. The polarization emitting spectrum around 2 μm is accomplished by exciting a singly Ho 3+ doped YVO 4 crystal to exclude the influence of Tm 3+3F 4- 3H 6 transition and the emission cross section is deduced from both Fuchtbauer-Ladenburg (F-L) equation and reciprocity method (RM). In addition, we report up to 10.4 W continuous wave (CW) output with a conversion efficiency of 40% and 10.3 W Q-Switch output with 12.5 kHz pulse repetition rate of diode-pumped cryogenic Tm,Ho:YVO 4 laser. For Q-Switch operation, the minimum pulse width of 28.2 ns is obtained, all of which demonstrate that the Tm,Ho:YVO 4 is excellent laser material for 2 μm radiation.

  9. All-fiber radially/azimuthally polarized lasers based on mode coupling of tapered fibers. (United States)

    Mao, Dong; He, Zhiwen; Lu, Hua; Li, Mingkun; Zhang, Wending; Cui, Xiaoqi; Jiang, Biqiang; Zhao, Jianlin


    We demonstrate a mode converter with an insertion loss of 0.36 dB based on mode coupling of tapered single-mode and two-mode fibers, and realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution of a tangential electric field at taper boundaries, the laser is switchable between the radially and azimuthally polarized states by adjusting the input polarization. In the temporal domain, the operation is controllable among continuous-wave, Q-switched, and mode-locked statuses by changing the saturable absorber or pump strength. The duration of Q-switched radially/azimuthally polarized laser spans from 10.4/10.8 to 6/6.4 μs at the pump range of 38 to 58 mW, while that of the mode-locked pulse varies from 39.2/31.9 to 5.6/5.2 ps by controlling the laser bandwidth. The proposed laser combines the features of a cylindrical vector beam, a fiber laser, and an ultrafast pulse, providing a special and cost-effective source for practical applications.

  10. Identification of an early damage of the retina by laser radiation

    International Nuclear Information System (INIS)

    Walther, G.; Hochgesand, P.; Stockhausen, M.; Valeske, W.


    The purpose of this investigation has been to find out the retinal threshold energy for a Q-switched Ruby-Laser with an impulse duration of 50 ns. A commercial Laser-Type (Fa. Eltrughs, Heidelberg, West Germany, Type CE 602) was used. For the test rabbits were used general anesthesia: the threshold energy was first determined ophthalmoscopically-enzyme-histochemically. In the first series the coagulation energy accounted between 7 x 10 -4 J and 9 x 10 -7 J, in the second between 10 -6 J and 1.5 x 10 -5 J. Clinically the threshold energy was found at a level of 3 - 5 x 10 -6 J, clinical-enzyme-histochemically at 1 - 2 x 10 -6 J. A theoretical and physical calculation leaded to 0.3 - 3 x 10 -6 J. Since the energy measurement varies and due to the different resorption qualities of the human and the rabbit's retina the threshold energy accounts 10 -7 J. Labour safety protection should prescribe a threshold energy less than 10 -8 J for a Q-switched Ruby-Laser of an impulse duration of 50 ns. (orig.) [de

  11. Generation of programmable temporal pulse shape and applications in micromachining (United States)

    Peng, X.; Jordens, B.; Hooper, A.; Baird, B. W.; Ren, W.; Xu, L.; Sun, L.


    In this paper we presented a pulse shaping technique on regular solid-state lasers and the application in semiconductor micromachining. With a conventional Q-switched laser, all of the parameters can be adjusted over only limited ranges, especially the pulse width and pulse shape. However, some laser link processes using traditional laser pulses with pulse widths of a few nanoseconds to a few tens of nanoseconds tend to over-crater in thicker overlying passivation layers and thereby cause IC reliability problems. Use of a laser pulse with a special shape and a fast leading edge, such as tailored pulse, is one technique for controlling link processing. The pulse shaping technique is based on light-loop controlled optical modulation to shape conventional Q-switched solid-state lasers. One advantage of the pulse shaping technique is to provide a tailored pulse shape that can be programmed to have more than one amplitude value. Moreover, it has the capability of providing programmable tailored pulse shapes with discrete amplitude and time duration components. In addition, it provides fast rising and fall time of each pulse at fairly high repetition rate at 355nm with good beam quality. The regular-to-shaped efficiency is up to 50%. We conclude with a discussion of current results for laser processing of semiconductor memory link structures using programmable temporal pulse shapes. The processing experiments showed promising results with shaped pulse.

  12. A highly efficient Ho:YAG laser in-band pumped by a linewidth-narrowed Tm:YLF laser

    International Nuclear Information System (INIS)

    Duan, X M; Yang, C H; Yao, B Q; Wang, Y Z; Zhang, W S


    A highly efficient Tm:YLF-Ho:YAG laser system is presented in this paper. To obtain the narrow linewidth 1908 nm laser output, a volume Bragg grating combined with a Fabry–Perot (FP) etalon were used as wavelength selection devices. The maximum output power of 28.7 W was obtained with a slope efficiency of 42.3% in the Tm:YLF laser. An output wavelength of 1908.1 nm and FWHM linewidth of 60 pm were achieved at the maximum output level. Using this Tm:YLF laser as the pump source, high efficiency continuous wave and Q-switched operation of a Ho:YAG laser was demonstrated. Operating at continuous wave mode, up to 73.3% slope efficiency and 67.4% optical conversion efficiency were obtained in the Ho:YAG laser, corresponding to a diode-to-Ho optical conversion efficiency of 23.7%. For the Q-switched mode, when the incident Tm power was 27.3 W, the maximum single pulse energy of 3.4 mJ, pulse width of 15 ns and peak power of 229.3 kW were achieved at the pulse repetition rate of 5 kHz. The maximum average power of 18.3 W, pulse width of 18 ns and peak power of 103.6 kW were obtained at the pulse repetition rate of 10 kHz. (paper)

  13. Resonator design and performance estimation for a space-based laser transmitter (United States)

    Agrawal, Lalita; Bhardwaj, Atul; Pal, Suranjan; Kamalakar, J. A.


    Development of a laser transmitter for space applications is a highly challenging task. The laser must be rugged, reliable, lightweight, compact and energy efficient. Most of these features are inherently achieved by diode pumping of solid state lasers. Overall system reliability can further be improved by appropriate optical design of the laser resonator besides selection of suitable electro-optical and opto-mechanical components. This paper presents the design details and the theoretically estimated performance of a crossed-porro prism based, folded Z-shaped laser resonator. A symmetrically pumped Nd: YAG laser rod of 3 mm diameter and 60 mm length is placed in the gain arm with total input peak power of 1800 W from laser diode arrays. Electro-optical Q-switching is achieved through a combination of a polarizer, a fractional waveplate and LiNbO 3 Q-switch crystal (9 x 9 x 25 mm) placed in the feedback arm. Polarization coupled output is obtained by optimizing azimuth angle of quarter wave plate placed in the gain arm. Theoretical estimation of laser output energy and pulse width has been carried out by varying input power levels and resonator length to analyse the performance tolerances. The designed system is capable of meeting the objective of generating laser pulses of 10 ns duration and 30 mJ energy @ 10 Hz.

  14. A diode-pumped Tm:CaYAlO4 laser at 1851 nm (United States)

    Lan, Jinglong; Guan, Xiaofeng; Xu, Bin; Moncorgé, Richard; Xu, Huiying; Cai, Zhiping


    Laser emission at ~1850 nm is of great interest for neural stimulation applications. In this letter, we report on the diode-pumped continuous-wave (CW) and Q-switched (QS) laser operation of Tm:CaYAlO4 at 1851 nm, for the first time to our knowledge. In the CW regime, a maximum output power up to 0.62 W is obtained with a laser slope efficiency of about 18.0%. Using a Cr:ZnSe saturable absorber, QS laser operation is achieved with a maximum average output power of 0.25 W, the narrowest pulse width of 107 ns and the highest repetition rate of 5.85 kHz. The corresponding pulse peak power and pulse energy are about 388 W and 42.8 µJ, respectively. In this Q-switched mode, wavelength tuning is also realized over about 3 nm by slightly tilting the saturable absorber.

  15. Laser at 532 nm by intracavity frequency-doubling in BBO (United States)

    Yuan, Xiandan; Wang, Jinsong; Chen, Yongqi; Wu, Yulong; Qi, Yunfei; Sun, Meijiao; Wang, Qi


    A simple and compact linear resonator green laser at 532 nm is generated by intracavity frequency-doubling of a diode-side-pumped acousto-optically (AO) Q-switched Nd:YAG laser at 1064 nm. Two acousto-optic Q-switches were placed orthogonally with each other to improve the hold-off capacity. As high as 214 W of continuous-wave (CW) and 154 W of quasi-continuous-wave (QCW) output power at 1064 nm were obtained when the pumping power was 1598 W. The type I phase-matched BBO crystal was used as the nonlinear medium in the second harmonic generation. A green laser with an average output power of 37 W was obtained at a repetition rate of 20 kHz and a pulse width of 54 ns, which corresponds to pulse energy of 1.85 mJ per pulse and a peak power 34.26 kW, respectively. Project supported by the Beijing Engineering Technology Research Center of All-Solid-State Lasers Advanced Manufacturing, the National High Technology Research and Development Program of China (No. 2014AA032607), and the National Natural Science Foundation of China (Nos. 61404135, 61405186, 61308032, 61308033).

  16. Resonance ionization spectroscopy using ultraviolet laser

    CERN Document Server

    Han, J M; Ko, D K; Park, H M; Rhee, Y J


    In this study, Ti:sapphire laser which is pumped by the enhanced Nd:YAG laser using laser diode, was designed and manufactured. The AO Q-switched CW Nd:YAG laser was converted into a high repetition plus-type laser using the AO Q-switch, and two heads were installed inside the cavity in order to improve the laser beam quality. The Nd:YAG laser enhancement was completed by optimization using a simulation for the cavity length, structure and thermal lens effect that greatly effected the laser beam output and quality. As the result of the enhancement, a 30W laser at 532nm and at 5k-Hz was successfully made. Also, the Ti:sapphire laser that will be used for atomic spectroscopy which is pumped by the Nd:YAG laser, was completely designed. As a basic experiment for laser oscillation. We measured the tunability of the laser, and it turned out that the wave tunability range was 730 850 nm. A self-seeding type tunable laser using grating for narrow line width, is planned to be designed due to the fact that the Ti:sapp...

  17. Comparative study of diode-pumping self-injection and injection-locking Tm:YAG lasers

    International Nuclear Information System (INIS)

    Wu, C T; Chen, F; Ju, Y L; Wang, Y Z


    A comparative study of the laser characteristics of self-injection and injection-locking Tm:YAG lasers is given in this paper. At a pump energy of 145 mJ and Q-switched repetition rate of 100 Hz, an output energy of 2.39 mJ was obtained for an injection-locking Tm:YAG laser, with a pulse width of 403.2 ns and a pulse building-up time of 2.12 μs. Under the same conditions, the output energy, pulse width and pulse build-up time for a self-injection Tm:YAG laser were 2.21 mJ, 407.0 ns and 3.95 μs, respectively. The threshold of the Q-switched injection-locking Tm:YAG laser was much lower than that of the self-injection laser, and the pulse width was narrower and the pulse build-up time shorter. Additionally, the output spectrum was much purer for the injection-locking laser. (paper)

  18. Compact erbium lasers in the IR photorefractive keratectomy (PRK) (United States)

    Liu, Baining; Eichler, Hans J.; Sperlich, O.; Holschbach, A.; Kayser, M.


    Erbium lasers deliver laser radiation near 3 micrometers and are a promising alternative to excimer laser photorefractive keratectomy (UV-PRK). In addition to easier handling due to all solid state technology, especially when operated in the fundamental mode, IR-PRK eliminates the potential of mutagenic side effects associated with UV-PRK. However, a successful IR-PRK for the clinic treatment in the near future demands both technological development of erbium lasers in different operation modes and clinical investigation of interaction between 3 micrometers radiation and human corneas. The excellent cooperation between university, company and hospital makes this possible. Uncoated thin plates made from infrared materials were found to be effective etalon reflectors with high damage threshold as high as 1 GW/cm2 for erbium lasers. Four kinds of such reflectors were successfully tested in Q-switched Er:YAG-laser at 2.94 micrometers and Er:Cr:YSGG-laser at 2.80 micrometers. Very stable operation of our erbium lasers with high output energy both in free-running and Q-switched modes is realized. First infrared photorefractive keratectomy (IR-PRK) for myopic correction in human corneas by a free-running erbium laser based on our new construction concepts was achieved.

  19. Fabrication and spectroscopic properties of Co:MgAl2O4 transparent ceramics by the HIP post-treatment (United States)

    Luo, Wei; Ma, Peng; Xie, Tengfei; Dai, Jiawei; Pan, Yubai; Kou, Huamin; Li, Jiang


    Cobalt-doped magnesium aluminate spinel (Co:MgAl2O4) is one of the most important saturable absorbers for the passive Q-switching of solid-state lasers operating at eye-safe wavelength of 1.5 μm. In this work, highly transparent Co:MgAl2O4 ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) post-treatment, using the mixture of the commercial spinel and the lab-made Co:MgAl2O4 powder as the raw materials. The densification mechanism of Co:MgAl2O4 transparent ceramics was discussed. The microstructure and optical properties of the samples were investigated. The ground state absorption cross section (σGSA) was calculated from the fitted curve of the absorption coefficient spectrum. The results show that Co:MgAl2O4 ceramics fabricated by vacuum sintering at 1500 °C for 5 h and then HIP post-treatment at 1650 °C for 3 h perform good transparency, whose in-line transmittance exceeds 80% at 2500 nm. Moreover, the ground state absorption cross section of 0.02 at.% Co:MgAl2O4 ceramics is calculated to be 3.35 × 10-19 cm2 at the wavelength of 1540 nm, which is promising for the application to the passive Q-switching of solid-state laser operating in the near infrared region (NIR).

  20. ZnO thin films on single carbon fibres fabricated by Pulsed Laser Deposition (PLD)

    Energy Technology Data Exchange (ETDEWEB)

    Krämer, André; Engel, Sebastian [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Sangiorgi, Nicola [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Department of Chemical Science and Technologies, University of Rome Tor Vergata, via della Ricerca Scientifica, 00133 Rome (Italy); Sanson, Alessandra [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Bartolomé, Jose F. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), C/Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Gräf, Stephan, E-mail: [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Müller, Frank A. [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena (Germany)


    Highlights: • Carbon fibres were entirely coated with thin films consisting of aligned ZnO crystals. • A Q-switched CO2 laser was utilised as radiation source. • Suitability of ZnO thin films on carbon fibres as photo anodes for DSSC was studied. - Abstract: Single carbon fibres were 360° coated with zinc oxide (ZnO) thin films by pulsed laser deposition using a Q-switched CO{sub 2} laser with a pulse duration τ ≈ 300 ns, a wavelength λ = 10.59 μm, a repetition frequency f{sub rep} = 800 Hz and a peak power P{sub peak} = 15 kW in combination with a 3-step-deposition technique. In a first set of experiments, the deposition process was optimised by investigating the crystallinity of ZnO films on silicon and polished stainless steel substrates. Here, the influence of the substrate temperature and of the oxygen partial pressure of the background gas were characterised by scanning electron microscopy and X-ray diffraction analyses. ZnO coated carbon fibres and conductive glass sheets were used to prepare photo anodes for dye-sensitised solar cells in order to investigate their suitability for energy conversion devices. To obtain a deeper insight of the electronic behaviour at the interface between ZnO and substrate I–V measurements were performed.

  1. Improved solid-state laser sources. Final technical report, 2 June 1981-1 June 1982

    International Nuclear Information System (INIS)

    Byer, R.L.


    During the first program year we have demonstrated diffraction limited output of 600 mJ from an unstable resonator Nd:Glass slab geometry oscillator. We have investigated, in detail, slab geometry lasers and have verified by careful experiments all important predictions of the slab theory. To date we have generated 10 J of output energy at 2.5 Hz from a single multimode, non-Q-switched, slab oscillator at 3.5% storage efficiency, 2% slope efficiency and 1.6% extraction efficiency. We have doubled and Raman shifted the Q-switched 600 mJ slab glass oscillator. We have extended the slab concept to Nd:YAG. Preliminary measurements show that the slab geometry eliminates thermal focusing and stress induced birefringence in Nd:YAG. We have demonstrated the advantages of the miniature pedestal growth technology by growing Eu:Y 2 O 3 single crystal fibers in addition to Nd:YAG and sapphire single crystal fibers

  2. Bio-effects of repetitively pulsed ultra-fast distributed feedback dye lasers

    International Nuclear Information System (INIS)

    Khan, N.; Ahmad, M.I.; Sheikh, A.


    Results of experimental study showing an unexpected rise in pulses of distributed feedback dye laser (DFDL) output due to temperature accumulation in dye cell during passively Q-Switched, a Mode-locked operation is reported. This unintended increase in number of pulse duration, per pulse energy may cause side-effects when used for selective photo thermolysis. To probe this phenomenon most commonly dye was excited with 10 to 20 pulses of second harmonic of a passively Q-Switched and Mode-locked Nd-YaG laser. The outputs of DFDL and Nd:YaG laser were recorded by Imacon 675-streak camera. The peak of DFDL output pulses was found delayed proportionally from the peak of the NYAG pulses by more than one inter-pulse period of excitation laser. A computer program was used to simulate the experimentally measured delay to estimate thermal decay constants and energy retained by the medium to determine the amount of incremental fluctuations in output. The delay between peaks of Nd:YAG (input) and DFDL(output) pulses was found to vary from 10 to 14 nanoseconds for various cavity lengths. It was found that for smaller inter-pulse periods the effect of gradual build-up satisfies the threshold conditions for some of the pulses that otherwise can not. This may lead to unintended increase in energy fluence causing overexposure-induced side-effects. (author)

  3. 3.5. Apparatus for plasma electron temperature measurement by Thomson scattering

    International Nuclear Information System (INIS)

    Kolacek, K.; Babicky, V.


    Equipment was developed and tested for measuring time-resolved local electron plasma temperature and density by the Thomson scattering of ruby laser light. The laser consists of a Q-switched generator (ruby 12 mm in diameter by 150 mm long) followed by one amplifier (ruby 16 mm indi long) followed by one amplifier (ruby 16 mm in diameter by 250 mm long). For Q-switching a Pockels cell with a z-cut ADP crystal was used. The laser is capable of delivering 4 J of energy in a pulse of 50 ns in duration. The spectrum of the laser light scattered at an angle of 9a degrees is analyzed by a six-channel polychromator. Fibre optics and photomultipliers with gated amplifiers are used. Output signals are transmitted via a parallel-to-series converter to a single-trace oscilloscope. The whole Thomson scattering apparatus was successfully tested by the Rayleigh scattering in the air at atmospheric pressure. (J.U.)

  4. A Laser Spark Plug Ignition System for a Stationary Lean-Burn Natural Gas Reciprocating Engine

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, D. L. [West Virginia Univ., Morgantown, WV (United States)


    To meet the ignition system needs of large bore, high pressure, lean burn, natural gas engines a side pumped, passively Q-switched, Nd:YAG laser was developed and tested. The laser was designed to produce the optical intensities needed to initiate ignition in a lean burn, high compression engine. The laser and associated optics were designed with a passive Q-switch to eliminate the need for high voltage signaling and associated equipment. The laser was diode pumped to eliminate the need for high voltage flash lamps which have poor pumping efficiency. The independent and dependent parameters of the laser were identified and explored in specific combinations that produced consistent robust sparks in laboratory air. Prior research has shown that increasing gas pressure lowers the breakdown threshold for laser initiated ignition. The laser has an overall geometry of 57x57x152 mm with an output beam diameter of approximately 3 mm. The experimentation used a wide range of optical and electrical input parameters that when combined produced ignition in laboratory air. The results show a strong dependence of the output parameters on the output coupler reflectivity, Q-switch initial transmission, and gain media dopant concentration. As these three parameters were lowered the output performance of the laser increased leading to larger more brilliant sparks. The results show peak power levels of up to 3MW and peak focal intensities of up to 560 GW/cm2. Engine testing was performed on a Ricardo Proteus single cylinder research engine. The goal of the engine testing was to show that the test laser performs identically to the commercially available flashlamp pumped actively Q-switched laser used in previous laser ignition testing. The engine testing consisted of a comparison of the in-cylinder, and emissions behavior of the engine using each of the lasers as an ignition system. All engine parameters were kept as constant as possilbe while the equivalence ratio (fueling

  5. Underwater Shock Wave Research Applied to Therapeutic Device Developments (United States)

    Takayama, K.; Yamamoto, H.; Shimokawa, H.


    The chronological development of underwater shock wave research performed at the Shock Wave Research Center of the Institute of Fluid Science at the Tohoku University is presented. Firstly, the generation of planar underwater shock waves in shock tubes and their visualization by using the conventional shadowgraph and schlieren methods are described. Secondly, the generation of spherical underwater shock waves by exploding lead azide pellets weighing from several tens of micrograms to 100 mg, that were ignited by irradiating with a Q-switched laser beam, and their visualization by using double exposure holographic interferometry are presented. The initiation, propagation, reflection, focusing of underwater shock waves, and their interaction with various interfaces, in particular, with air bubbles, are visualized quantitatively. Based on such a fundamental underwater shock wave research, collaboration with the School of Medicine at the Tohoku University was started for developing a shock wave assisted therapeutic device, which was named an extracorporeal shock wave lithotripter (ESWL). Miniature shock waves created by irradiation with Q-switched HO:YAG laser beams are studied, as applied to damaged dysfunctional nerve cells in the myocardium in a precisely controlled manner, and are effectively used to design a catheter for treating arrhythmia.

  6. Novel laterally pumped by prism laser configuration for compact solid-state lasers

    International Nuclear Information System (INIS)

    Dascalu, T; Salamu, G; Sandu, O; Voicu, F; Pavel, N


    We propose a new laser configuration in which the pump radiation is coupled into the laser crystal through a prism. The laser medium is square shaped and the prism is attached on one of its lateral sides, near one of the crystal extremities. The diode-laser fiber end is placed close to the prism hypotenuse, the pump radiation is coupled into the laser crystal through the opposite surface of the prism and propagates into the crystal through total internal reflections. This laser geometry is simple to align and permits the realization of compact diode-pumped laser systems, as well as power scaling. A diode-pumped Nd:YAG laser yielding pulses of 2.1 mJ energy under a pump with pulses of 9.9 mJ is demonstrated. The laser slope efficiency is 0.22. Furthermore, this geometry enables one to obtain passively Q-switched lasers with the saturable absorber crystal placed between the resonator high-reflectivity mirror and the laser crystal. A Nd:YAG laser, passively Q-switched by a Cr 4+ :YAG crystal with initial transmission T 0 = 0.90, delivering laser output with a pulsed energy of 93 μJ, a duration of 26 ns and a pump threshold of 1.9 mJ, is realized in order to prove the concept. (letter)

  7. 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement (United States)

    Singh, Upendra N.; Bai, Yingxin; Yu, Jirong


    Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam

  8. Experimental investigation of the vibrational and thermal response of a laser spark plug (United States)

    Yoder, Gregory S.

    A study was conducted in order to evaluate the external thermal and vibrational effects on the operation of a laser ignition system for internal combustion (IC) engine applications. West Virginia University (WVU) in conjunction with the National Energy Technology Laboratory (NETL) have constructed a prototype laser spark plug which has been designed to mount directly onto the head of a natural gas engine for the purpose of igniting an air/fuel (A/F) mixture in the engine's combustion chamber. To be considered as a viable replacement for the conventional electrode-based ignition system, integrity, durability and reliability must be justified. Thermal and oscillatory perturbations induced upon the ignition system are major influences that affect laser spark plug (LSP) operation and, therefore, quantifying these effects is necessary to further the advancement and development of this technology. The passively q-switched Nd:YAG laser was mounted on Bruel & Kjaer (B&K) Vibration Exciter Type 4808 Shaker in conjunction with at B&K Power Amplifier Type 2719, which was oscillated in 10 Hz intervals from 0 to 60 Hz using a sine wave to mimic natural gas engine operation. The input signal simulated the rotational velocity of the engine operating from 0 to 3600 RPM with the laser mounted in three different axial orientations. The laser assembly was wrapped with medium-temperature heat tape, outfitted with thermocouples and heated from room temperature to 140 ºF to simulate the temperatures that the LSP may experience when installed on an engine. The acceleration of the payload was varied between 50% and 100% of the oscillator's maximum allowable acceleration in each mounting orientation resulting in a total of 294 total setpoints. For each setpoint, pulse width, pulse width variation, q-switch delay, jitter and output energy were measured and recorded. Each of these dependent variables plays a critical role in multi photon ionization and precise control is necessary to limit

  9. In vitro studies with a pulsed neodymium/YAG laser. (United States)

    Venkatesh, S; Guthrie, S; Foulds, W S; Lee, W R; Cruickshank, F R; Bailey, R T


    The relationships between the destructive effects of Q-switched Nd/YAG laser pulses and a number of experimental parameters were studied for various target materials including in particular excised, fixed samples of human trabecular meshwork. The laser parameters altered were the pulse energy, the convergence angle of the focused beam, and the position of the focus of the beam relative to the target's axial position. The main finding was that it was possible to make deep holes, of a diameter less than 100 micron, in virtually transparent samples of trabecular meshwork with a laser delivery system of 6 degrees convergence and pulse energies of 14 mJ or more. The relevance of this and the other experimental results to the development of a reliable system for performing internal trabeculotomies for the treatment of open-angle glaucoma is presented.

  10. The application of μPIV technique in the study of magnetic flows in a micro-channel

    International Nuclear Information System (INIS)

    Nguyen, N.T.; Wu, Z.G.; Huang, X.Y.; Wen, C.-Y..


    In this preliminary experimental study, micro-scale particle image velocimetry (μPIV) was adopted for the first time to get the quantitative information of magnetic flows in a micro-channel. The μPIV consists of an inverted florescent microscope, a Q-switch Nd:YAG laser and a CCD camera. The florescent liquid with particles of 3 μm diameter was blended homogeneously with the prepared magnetic fluid. A permanent magnet approached and left one end of the micro-channel. The response of the magnetic fluid was recorded with the μPIV simultaneously. The flow features validate the feasibility of using μPIV technique in the study of magnetic flows in a micro-channel. μPIV provides a promising experimental tool for visualization and quantitative measurement of magnetic micro-flows

  11. Saturable Absorption and Modulation Characteristics of Laser with Graphene Oxide Spin Coated on ITO Substrate

    Directory of Open Access Journals (Sweden)

    Xin Li


    Full Text Available The graphene oxide (GO thin film has been obtained by mixture of GO spin coated on substrate of indium tin oxide (ITO. The experiment has shown that continuous-wave laser is modulated when the graphene oxide saturable absorber (GO-SA is employed in the 1064 nm laser cavity. The shortest pulse width is 108 ns at the pump power of 5.04 W. Other output laser characteristics, such as the threshold pump power, the repetition rate, and the peak power, have also been measured. The results have demonstrated that graphene oxide is an available saturable absorber for 1064 nm passive Q-switching laser.

  12. Morphological and optical properties of silicon thin films by PLD

    International Nuclear Information System (INIS)

    Ayouchi, R.; Schwarz, R.; Melo, L.V.; Ramalho, R.; Alves, E.; Marques, C.P.; Santos, L.; Almeida, R.; Conde, O.


    Silicon thin films have been prepared on sapphire substrates by pulsed laser deposition (PLD) technique. The films were deposited in vacuum from a silicon target at a base pressure of 10 -6 mbar in the temperature range from 400 to 800 deg. C. A Q-switched Nd:YAG laser (1064 nm, 5 ns duration, 10 Hz) at a constant energy density of 2 J x cm -2 has been used. The influence of the substrate temperature on the structural, morphological and optical properties of the Si thin films was investigated. Spectral ellipsometry and atomic force microscopy (AFM) were used to study the thickness and the surface roughness of the deposited films. Surface roughness values measured by AFM and ellipsometry show the same tendency of increasing roughness with increased deposition temperature

  13. Compact sources for eyesafe illumination (United States)

    Baranova, Nadia; Pu, Rui; Stebbins, Kenneth; Bystryak, Ilya; Rayno, Michael; Ezzo, Kevin; DePriest, Christopher


    Q-peak has demonstrated a compact, pulsed eyesafe laser architecture operating with >10 mJ pulse energies at repetition rates as high as 160 Hz. The design leverages an end-pumped solid-state laser geometry to produce adequate eyesafe beam quality (M2˜4), while also providing a path toward higher-density laser architectures for pulsed eyesafe applications. The baseline discussed in this paper has shown a unique capability for high-pulse repetition rates in a compact package, and offers additional potential for power scaling based on birefringence compensation. The laser consists of an actively Q-switched oscillator cavity producing pulse widths designed to fit within a volume of 3760 cm3. We will discuss details of the optical system design, modeled thermal effects and stress-induced birefringence, as well as experimental advantages of the end-pumped laser geometry, along with proposed paths to higher eyesafe pulse energies.

  14. Development of Cr,Nd:GSGG laser as a pumping source of Ti:sapphire laser

    International Nuclear Information System (INIS)

    Tamura, Koji; Arisawa, Takashi


    Since efficiency of Cr,Nd doped gadolinium scandium gallium garnet (GSGG) laser is in principle higher than that of Nd:YAG laser, it can be a highly efficient pumping source for Ti:sapphire laser. We have made GSGG laser, and measured its oscillation properties. It was two times more efficient than Nd:YAG laser at free running mode operation. At Q-switched mode operation, fundamental output of 50 mJ and second harmonics output of 8 mJ were obtained. The developed laser had appropriate spatial profile, temporal duration, long time stability for solid laser pumping. Ti:sapphire laser oscillation was achieved by the second harmonics of GSGG laser. (author)

  15. Apraclonidine effects on ocular responses to YAG laser irradiation to the rabbit iris

    International Nuclear Information System (INIS)

    Sugiyama, K.; Kitazawa, Y.; Kawai, K.


    Apraclonidine (p-aminoclonidine) ophthalmic solution effectively reduces the rise in intraocular pressure (IOP) following anterior segment laser surgery. We tested the effect of topical 0.5% apraclonidine on intraocular pressure and on protein and prostaglandin (PG) E2 concentrations in aqueous humor following Q-switched Nd:YAG laser irradiation to the iris of albino rabbits, at an energy level of 2 to 200 mJ. IOP was measured prior to and for 24 hr after irradiation. Aqueous humor was withdrawn before and 1 hr after laser irradiation for determining protein (Lowry method) and PGE2 (radioimmunoassay). Four to seven rabbits were used for each experiment. The increase in IOP and protein concentration following laser irradiation was demonstrated to be dependent on the amount of laser energy. Apraclonidine completely abolished the IOP rise, and significantly reduced the elevation of protein content. Apraclonidine failed to affect the increase in PGE2

  16. Growth, thermal properties and laser operation of a novel disordered Yb:Ca3La2(BO3)4 laser crystal (United States)

    Pan, Zhongben; Cai, Huaqiang; Huang, Hui; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang


    A high quality disordered Yb:Ca3La2(BO3)4 laser crystal has been successfully grown by the Czochralski method. The complete set of anisotropic thermal properties were systematically measured for the first time. In addition, continuous-wave laser along the three crystallographic axis were obtained. Passively Q-switched by a Cr4+:YAG saturable absorber, the laser yielded an average output power of 0.47 W with a slope efficiency of 7.6% for the first time. The generated pulse energy, duration, and peak power were 94 μJ, 33 ns, and 2.85 KW, respectively. We believe that the reliability and stability of these lasers makes the disordered Yb:Ca3La2(BO3)4 crystal of considerable interest for future applications.

  17. Diode-pumped laser with Yb:YAG single-crystal fiber grown by the micro-pulling down technique (United States)

    Sangla, D.; Aubry, N.; Didierjean, J.; Perrodin, D.; Balembois, F.; Lebbou, K.; Brenier, A.; Georges, P.; Tillement, O.; Fourmigué, J.-M.


    Laser emission obtained from an Yb:YAG single-crystal fiber directly grown by the micro-pulling down technique is demonstrated for the first time. We achieved 11.2 W of continuous wave (CW) output power at 1031 nm for 55 W of incident pump power at 940 nm. In the Q-switched regime, we obtained pulses as short as 17 ns, for an average power of 2.3 W at 2 kHz corresponding to an energy of 1.15 mJ. In both cases, the M 2 factor was 2.5. This single-crystal fiber showed performance similar to a standard rod elaborated by the Czochralski method. The potential of Yb3+-doped single-crystal fibers is presented for scalable high-average and high-peak-power laser systems.

  18. Cleaning of the first mirrors and diagnostic windows by YAG laser on HL-2A

    International Nuclear Information System (INIS)

    Zhou, Y; Zheng, L; Li, Y G; Li, L C; Jiao, Y M; Gao, H; Zhao, G


    A laser cleaning system for HL-2A tokamak first mirrors and diagnostic windows has been developed recently. A detailed description of the laser cleaning procedure is presented. The optical transmission performance measured before and after the laser cleaning of the impurity film deposited on the optical elements is investigated. HL-2A deposited layers on metal mirrors and glass windows with thicknesses of about 1 and 4 μm, respectively, are clearly removed by irradiation with a single pulse of a Q-switched Nd:YAG laser with energy density of 0.4 and 2.8 J cm -2 , respectively. The feasibility of cleaning ECE windows is demonstrated. A cleaning time of about 5 min is suitable for application in fusion devices. The comparison of results obtained at different laser wavelengths shows that there is a greater probability of damage to the metallic mirror surface with a short laser wavelength than with longer wavelength.

  19. Laser-generated acoustic wave studies on tattoo pigment (United States)

    Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.


    A Q-switched alexandrite laser (180 ns at 755 nm) was used to irradiate samples of agar embedded with red, black and green tattoo dyes. The acoustic waves generated in the samples were detected using a PVDF membrane hydrophone and compared to theoretical expectations. The laser pulses were found to generate acoustic waves in the black and green samples but not in the red pigment. Pressures of up to 1.4 MPa were produced with irradiances of up to 96 MWcm-2 which is comparable to the irradiances used to clear pigment embedded in skin. The pressure gradient generated across pigment particles was approximately 1.09 X 1010 Pam-1 giving a pressure difference of 1.09 +/- 0.17 MPa over a particle with mean diameter 100 micrometers . This is not sufficient to permanently damage skin which has a tensile strength of 7.4 MPa.

  20. Investigations on the nucleation kinetics of γ-glycine single crystal

    International Nuclear Information System (INIS)

    Yogambal, C.; Rajan Babu, D.; Ezhil Vizhi, R.


    Single crystals of γ-glycine were grown by slow evaporation technique. The crystalline system was confirmed by single crystal X-ray diffraction analysis. The optical absorption study has shown that the grown crystal possesses lower cut-off wavelength. Solubility and metastable zone width were estimated for different temperatures. The induction period of title compound was determined by varying the temperature and concentration. Nucleation parameters such as Gibbs volume free energy change (ΔG v ), interfacial tension (γ), critical free energy change of the nucleus (ΔG ⁎ ), nucleation rate (J), number of molecules in the critical nucleus (i ⁎ ) have been calculated for the aqueous solution grown γ-glycine single crystals. The second harmonic generation (SHG) of γ-glycine was confirmed by Q-switched Nd:YAG laser technique

  1. Damage threshold from large retinal spot size repetitive-pulse laser exposures. (United States)

    Lund, Brian J; Lund, David J; Edsall, Peter R


    The retinal damage thresholds for large spot size, multiple-pulse exposures to a Q-switched, frequency doubled Nd:YAG laser (532 nm wavelength, 7 ns pulses) have been measured for 100 μm and 500 μm retinal irradiance diameters. The ED50, expressed as energy per pulse, varies only weakly with the number of pulses, n, for these extended spot sizes. The previously reported threshold for a multiple-pulse exposure for a 900 μm retinal spot size also shows the same weak dependence on the number of pulses. The multiple-pulse ED50 for an extended spot-size exposure does not follow the n dependence exhibited by small spot size exposures produced by a collimated beam. Curves derived by using probability-summation models provide a better fit to the data.

  2. Measurements of three dimensional residual stress distribution on laser irradiated spot

    International Nuclear Information System (INIS)

    Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki


    Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

  3. Active beam position stabilization of pulsed lasers for long-distance ion profile diagnostics at the Spallation Neutron Source (SNS). (United States)

    Hardin, Robert A; Liu, Yun; Long, Cary; Aleksandrov, Alexander; Blokland, Willem


    A high peak-power Q-switched laser has been used to monitor the ion beam profiles in the superconducting linac at the Spallation Neutron Source (SNS). The laser beam suffers from position drift due to movement, vibration, or thermal effects on the optical components in the 250-meter long laser beam transport line. We have designed, bench-tested, and implemented a beam position stabilization system by using an Ethernet CMOS camera, computer image processing and analysis, and a piezo-driven mirror platform. The system can respond at frequencies up to 30 Hz with a high position detection accuracy. With the beam stabilization system, we have achieved a laser beam pointing stability within a range of 2 μrad (horizontal) to 4 μrad (vertical), corresponding to beam drifts of only 0.5 mm × 1 mm at the furthest measurement station located 250 meters away from the light source.

  4. Materials testing using laser energy deposition

    International Nuclear Information System (INIS)

    Wilcox, W.W.; Calder, C.A.


    A convenient method for determining the elastic constants of materials has been devised using the energy from a Q-switched neodymium-glass laser. Stress waves are induced in materials having circular rod or rectangular bar geometries by the absorption of energy from the laser. The wave transit times through the material are recorded with a piezoelectric transducer. Both dilatation and shear wave velocities are determined in a single test using an ultrasonic technique and these velocities are used to calculate the elastic constants of the material. A comparison of the constants determined for ten common engineering materials using this method is made with constants derived using the conventional ultrasonic pulse technique and agreement is shown to be about one percent in most cases. Effects of material geometry are discussed and surface damage to the material caused by laser energy absorption is shown

  5. One-step synthesis of Zn/ZnO hollow nanoparticles by the laser ablation in liquid technique

    International Nuclear Information System (INIS)

    Desarkar, H S; Kumbhakar, P; Mitra, A K


    Here, one-step synthesis of Zn/ZnO hollow nanoparticles along with solid nanoparticles is reported using the laser ablation in liquid (LAL) technique. Laser radiation of the 1064 nm wavelength is emitted from a Q-switched Nd:YAG laser and is incident on a solid zinc target kept in a water medium. The as-obtained hollow and solid particles are characterized by transmission electron microscopy (TEM) and UV–visible absorption spectroscopy. Hollow nanoparticles are produced by the laser generated bubbles produced in water. The surface of a hollow nanoparticle is assembled from smaller solid nanoparticles. A strong laser–particle interaction is also observed when laser ablation is carried out for a longer time duration. Photoluminescence (PL) emission measurements at room temperature show that all samples exhibit PL emission in the UV–visible region. A reduction in size and an increase in concentration of the synthesized nanoparticles is observed with increasing laser ablation time. (letter)

  6. Optical fiber array for the delivery of high peak-power laser pulses for fluid flow measurements

    International Nuclear Information System (INIS)

    Parry, Jonathan P.; Shephard, Jonathan D.; Thomson, Martin J.; Taghizadeh, Mohammad R.; Jones, Julian D. C.; Hand, Duncan P.


    Fiber delivery of 64.7 mJ laser pulses (∼6 ns duration) from a Q-switched Nd:YAG laseroperating at532 nm is demonstrated. A custom diffractive optical element was used toshape the laser beam and facilitate coupling into a linear fiber array. This launcharrangement achieves an improvement in launch efficiency compared with a circular fiberbundle evaluated in previous work and the delivery of higher pulse energies isdemonstrated. The bundle is capable of delivering light of sufficient pulse energy and,importantly, with suitable focusability, to generate a thin light sheet for the fluid flowmeasurement technique of particle image velocimetry (PIV). Fiber delivery offers anadvantage, in terms of optical access, for the application of PIV to enclosed measurementvolumes, such as the cylinder of a combustion engine

  7. Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression (United States)

    Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki


    We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

  8. A photoacoustic tomography system for imaging of biological tissues

    International Nuclear Information System (INIS)

    Su Yixiong; Zhang Fan; Xu Kexin; Yao Jianquan; Wang, Ruikang K


    Non-invasive laser-induced photoacoustic tomography (PAT) is a promising imaging modality in the biomedical optical imaging field. This technology, based on the intrinsic optical properties of tissue and ultrasonic detection, overcomes the resolution disadvantage of pure-optical imaging caused by strong light scattering and the contrast and speckle disadvantages of pure ultrasonic imaging. Here, we report a PAT experimental system constructed in our laboratory. In our system, a Q-switched Nd : YAG pulse laser operated at 532 nm with a 8 ns pulse width is used to generate a photoacoustic signal. By using this system, the two-dimensional distribution of optical absorption in the tissue-mimicking phantom is reconstructed and has an excellent agreement with the original ones. The spatial resolution of the imaging system approaches 100 μm through about 4 cm of highly scattering medium

  9. Comparison of three different laser systems for application in dentistry (United States)

    Mindermann, Anja; Niemz, M. H.; Eisenmann, L.; Loesel, Frieder H.; Bille, Josef F.


    Three different laser systems have been investigated according to their possible application in dentistry: a free running and a Q-switched microsecond Ho:YAG laser, a free running microsecond Er:YAG laser and picosecond Nd:YLF laser system consisting of an actively mode locked oscillator and a regenerative amplifier. The experiments focused on the question if lasers can support or maybe replace ordinary drilling machines. For this purpose several cavities were generated with the lasers mentioned above. Their depth and quality were judged by light and electron microscopy. The results of the experiments showed that the picosecond Nd:YLF laser system has advantages compared to other lasers regarding their application in dentistry.

  10. Study on the drive laser system of the photocathode-injector used in high gain FEL

    CERN Document Server

    Lu Xiang Yang; Zhao Kui; Wang Li; Quan Sheng Wen; Hao Jian Kui; Zhang Bao Cheng; Chen J


    High gain FEL requires high quality electron beam which can be provided only by the RF photocathode gun. The drive laser for electron source plays the key role. In Institute of Heavy Ion Physics of Beijing University, the laser system is required to deliver a 500 mu J, 6-8 ps pulse of UV photons (260 nm) to the cathode. This system mainly consists of a CW, frequency-doubled, diode-pumped Nd:YAG laser, which provides energy to pump a CW mode-locked Ti:sapphire oscillator, Q-switched Nd:YaG pump lasers, a regenerative amplifier and harmonics crystals. To meet the low jitters of pulses (1.0 ps), cavity length of the oscillator should be adjustable to lock the pulse frequency with external RF reference, and a phase stability feedback system is also used

  11. A high-energy, low-threshold tunable intracavity terahertz-wave parametric oscillator with surface-emitted configuration

    International Nuclear Information System (INIS)

    Wang, Y Y; Xu, D G; Jiang, H; Zhong, K; Yao, J Q


    A high-energy, low-threshold THz-wave output has been experimentally demonstrated with an intracavity terahertz-wave parametric oscillator based on a surface-emitted configuration, which was pumped by a diode-side-pumped Q-switched Nd:YAG laser. Different beam sizes and repetition rates of the pump light have been investigated for high-energy and high-efficiency THz-wave generation. The maximum THz-wave output energy of 283 nJ/pulse was obtained at 1.54 THz under an intracavity 1064 nm pump energy of 59 mJ. The conversion efficiency was 4.8 × 10 −6 , corresponding to a photon conversion efficiency of 0.088%. The pump threshold was 12.9 mJ/pulse. A continuously tunable range from 0.75 to 2.75 THz was realized. (paper)

  12. Estimation of Soil Nitrate (NO3) Level Using Laser-Induced Breakdown Spectroscopy (LIBS) (United States)

    Angkat, A. R.; Seminar, K. B.; Rahmat, M.; Sutandi, A.


    Laser-Induced Breakdown Spectroscopy (LIBS) is a method for measuring level of nitrogen (N) in the soil in the form of N-nitrate (NO3) rapidly without going through the process of sieving and drying. The sample soil in the form of pellets subjected to laser pulses using a wavelength of 532 nm, pulse duration 5.5 ns, repetition rate of 10 Hz, and Q-switch delay of 150 μs. Emissions are captured by the spectrometer with the wavelength range of 190-1130 nm. Spectrum characterization was processed through the second derivative in order to obtain a wavelength identity that could be rapidly used to estimate the nitrate content of the soil with a determination coefficient of (R2) 0.9254 and a coefficient of variation (CV) of 8.41%. The results of this study are very potential to be applied for rapid measurement of soil nitrate.

  13. Laser Resonators and Beam Propagation Fundamentals, Advanced Concepts and Applications

    CERN Document Server

    Hodgson, Norman


    Optical Resonators provides a detailed discussion of the properties of optical resonators for lasers from basic theory to recent research. In addition to describing the fundamental theories of resonators such as geometrical optics, diffraction, and polarisation the characteristics of all important resonator schemes and their calculation are presented. Experimental examples, practical problems and a collection of measurement techniques support the comprehensive treatment of the subject. Optical Resonators is the only book currently available that provides a comprehensive overview of the the subject. Combined with the structure of the text and the autonomous nature of the chapters this work will be as suitable for those new to the field as it will be invaluable to specialists conducting research. This second edition has been enlarged by new sections on Q-switching and resonators with internal phase/amplitude control. In addition, the whole book has been brought up-to-date.

  14. Analysis of organic vapors with laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh


    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor

  15. submitter Triggering of a pressurized spark gap by a laser beam

    CERN Document Server

    Deutsch, F


    A delay line was discharged into a terminating resistor by a spark gap of coaxial design. The spark gap was triggered by a focused laser beam, introduced along the axis; a Q-switched ruby laser giving pulses of 20 ns duration and up to 50 MW power was used. The range of operation of the gap, formative time of the breakdown and jitter were investigated for different gases at pressures above atmospheric, gap widths of 4-10 mm and voltages of up to 120 kv. Mixtures of argon and nitrogen were found to have certain advantages, such as a low threshold for ionization by the laser beam, sufficient dielectric strength, low values of the formative-time jitter and chemical inertness. Formative times of down to about 1 ns and jitters below 1 ns were found. The laser power can be relatively low (0centerdot5-5 MW). An explanation for the breakdown mechanism is proposed.

  16. Numerical simulation of a battlefield Nd:YAG laser (United States)

    Henriksson, Markus; Sjoqvist, Lars; Uhrwing, Thomas


    A numeric model has been developed to identify the critical components and parameters in improving the output beam quality of a flashlamp pumped Q-switched Nd:YAG laser with a folded Porro-prism resonator and polarization output coupling. The heating of the laser material and accompanying thermo-optical effects are calculated using the finite element partial differential equations package FEMLAB allowing arbitrary geometries and time distributions. The laser gain and the cavity are modeled with the physical optics simulation code GLAD including effects such as gain profile, thermal lensing and stress-induced birefringence, the Pockels cell rise-time and component aberrations. The model is intended to optimize the pumping process of an OPO providing radiation to be used for ranging, imaging or optical countermeasures.

  17. 2.07-micron CW diode-laser-pumped Tm,Ho:YLiF4 room-temperature (United States)

    Hemmati, Hamid


    Continuous-wave action is obtained at 2.07 microns from a 2-mm-long Tm-sensitized Ho:YLiF4 crystal at room temperature when longitudinally pumped by a pair of diode-laser arrays. Laser output power at 300 K is 26 mW, with a 30-percent slope efficiency and a lasing threshold of 108 mW. A maximum output power of 187 mW is obtained from a 4-mm-long crystal at 77 K, with a 67 percent slope efficiency. A preliminary demonstration of cavity Q switching produced 165 microJ of pulse energy at a repetition rate of 100 Hz.

  18. Laser amplification of optical images using a CW Nd:YAG amplifier

    International Nuclear Information System (INIS)

    Aman, H


    In this paper a scheme for the amplification of optical images is described, using a continuous wave (CW) diode-pumped Nd:YAG (yttrium aluminum garnet) laser module. A passively q-switched end-pumped Nd:YAG laser is used as a pump source, which carries the optical image distribution as an input which is transmitted towards the amplifier at a distance of about ten feet. For amplification, a three-side-pumped CW Nd:YAG laser module is utilized without the cavity mirrors. In this way, optical images are amplified by a factor of 3.2 and imaged at a distance of ten feet with a spatial resolution of 500 μm. (paper)

  19. Resonantly diode pumped Er:YAG laser systems emitting at 1645 nm for methane detection

    International Nuclear Information System (INIS)

    Fritsche, H; Lux, O; Wang, X; Zhao, Z; Eichler, H J


    We report on the development of compact and frequency-stable Er:YAG laser systems emitting in the eye-safe spectral region. Resonant cw diode pumping provides 4.5 W output power in cw operation and 2.2 mJ in Q-switched operation with pulse duration of about 140 ns. The application of intra-cavity etalons allows for wavelength tuning from 1645.22 to 1646.33 nm while the frequency stability accounts for less than 50 MHz. The potential of the erbium laser sources in terms of methane detection was evaluated under laboratory conditions by absorption measurements employing a multi-pass absorption cell. The experimental investigations were accompanied by theoretical studies on the influence of pressure broadening on the absorption behavior of methane. (letter)

  20. Self-trapped excitonic green emission from layered semiconductors

    International Nuclear Information System (INIS)

    Miah, M. Idrish


    Crystals of layered semiconductor are grown by Bridgman technique and are studied them under two-photon excitation by a Q-switched 20-ns pulse laser. The photoluminescence (PL) emission spectra of the crystals are measured at various pumping powers and temperatures. The PL spectra appear broad and structureless emissions with their peaks in the green spectral region. The characteristic emissions are from self-trapped excitons of the crystals. An analysis of the spectra measured at various pumping powers shows a quadratic dependence of the PL peak intensity on the power, confirming a biphotonic process of the two-photon pumping. The temperature dependence shows an enhancement of the nonlinear response at low temperatures. The activation energy is estimated and found to be 2.4 meV. The roles of the bound excitons in the observed PL are discussed briefly.

  1. Self-trapped excitonic green emission from layered semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)


    Crystals of layered semiconductor are grown by Bridgman technique and are studied them under two-photon excitation by a Q-switched 20-ns pulse laser. The photoluminescence (PL) emission spectra of the crystals are measured at various pumping powers and temperatures. The PL spectra appear broad and structureless emissions with their peaks in the green spectral region. The characteristic emissions are from self-trapped excitons of the crystals. An analysis of the spectra measured at various pumping powers shows a quadratic dependence of the PL peak intensity on the power, confirming a biphotonic process of the two-photon pumping. The temperature dependence shows an enhancement of the nonlinear response at low temperatures. The activation energy is estimated and found to be 2.4 meV. The roles of the bound excitons in the observed PL are discussed briefly.

  2. Digital Communication System Based on Polarization Self-Modulation in Lasers (United States)

    Tabarin, V. A.; Ikonnikov, V. P.; Shatalov, A. N.


    Polarization self-modulation in lasers can be used to create instruments for generating optical pulses at very high repetition rates without using high-speed electronics. Self-oscillation is observed when part of the output of a laser is returned to the laser after a 90° polarization change. A practical scheme based on polarization self-modulation in a 3.39-μm helium-neon laser is proposed for pulsed code data transmission with an yttrium-iron garnet magnetooptical Q-switch. Highly efficient transmission of digital signals is implemented with a repetition rate of 75 MHz, equivalent to half the free spectral range of the laser.

  3. Highly-stable monolithic femtosecond Yb-fiber laser system based on photonic crystal fibers

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry


    in the oscillator cavity for dispersion balancing and nonlinear optical limiting, and another one is used for low nonlinearity final pulse recompression. The chirped-pulse amplification and recompression of the 232-fs, 45-pJ/pulse oscillator output yields a final direct fiber-end delivery of 7.3-nJ energy pulses......A self-starting, passively stabilized, monolithic all polarizationmaintaining femtosecond Yb-fiber master oscillator / power amplifier with very high operational and environmental stability is demonstrated. The system is based on the use of two different photonic crystal fibers. One is used...... of around 297 fs duration. Our laser shows exceptional stability. No Q-switched modelocking events were detected during 4-days long observation. An average fluctuation of only 7.85 · 10−4 over the mean output power was determined as a result of more than 6-hours long measurement. The laser is stable towards...

  4. Femtosecond all-polarization-maintaining fiber laser operating at 1028 nm

    DEFF Research Database (Denmark)

    Olsson, R.K.; Andersen, T.V.; Leick, Lasse


    We present an effective solution for an all-polarization-maintaining modelocked femtosecond fiber laser operating at the central wavelength of 1028 nm. The laser is based on an Yb-doped active fiber. Modelocking is enabled by a semiconductor saturable absorber mirror, and the central wavelength i...... is enforced by a fiber Bragg grating. The laser is self-starting and demonstrates excellent stability gainst Q-switching. Pulse energies reach 13 nJ at 34 MHz repetition rate. External compression leads to near transform-limited pulses of 140 fs.......We present an effective solution for an all-polarization-maintaining modelocked femtosecond fiber laser operating at the central wavelength of 1028 nm. The laser is based on an Yb-doped active fiber. Modelocking is enabled by a semiconductor saturable absorber mirror, and the central wavelength...

  5. Generation of short optical pulses for laser fusion. M.L. report No. 2451

    International Nuclear Information System (INIS)

    Kuizenga, D.J.


    This report considers some of the problems involved in generating the required short pulses for the laser-fusion program. Short pulses are required to produce the laser fusion, and pulses produced synchronously with this primary pulse are required for plasma diagnostics. The requirements of these pulses are first described. Several methods are considered in order to generate pulses at 1.064 μ to drive the Nd:Glass amplifiers to produce laser fusion. Conditions for optimum energy extraction per short pulse for Nd:YAG and Nd:Glass lasers are given. Four methods are then considered to produce these pulses: (1) using a fast switch to chop the required pulse out of a much longer Q-switched pulse; (2) active mode locking; (3) passive mode locking; and (4) a combination of active and passive mode locking. The use of cavity dumping is also considered to increase the energy per short pulse

  6. Laser cleaner development for decontamination of the primary water cooling system at nuclear power plants

    International Nuclear Information System (INIS)

    Minehara, Eisuke


    We recently have performed the feasibility studies to develop laser cleaners utilizing several laser oscillator and amplifier systems like femto-second free-electron lasers, water-jet guided lasers, Q-switched YAG lasers, fiber lasers. Whenever we used to clean the RI-contaminated surface using the lasers, we should focus enough laser power in the surface to evaporate instantly without melting. Therefore, as the contaminated being deeply located into the surface could be removed using any one set of the lasers, we found that every trial of laser cleaning could remove very well the RI contamination being located deeply. Our cold decontamination test using a model sample being Cobalt plated successfully has been performed to show a very high decontamination factor. In order to develop an usable laser cleaner, we plan to develop the prototype laser cleaner next year. (author)

  7. Detection and Investigation of Carbon Ions Induced by Nd:YAG laser using SSNTDs

    International Nuclear Information System (INIS)

    Qindeel, Rabia; Ali, Jalil Bin; Chaudhary, K. T.; Hussain, M. S.


    A Q-Switched Nd:YAG laser pulse of pulsed width of 9∼14 ns, wavelength of 1064 nm, repetition rate of 0.5 Hz, power of 1.1 MW and energy of 10 mJ has been used to ablate the 4N pure graphite target through IR lens. Solid state nuclear track detector (SSNTD) CR-39 has been used to calculate the energy of carbon ions produced as a result of laser ablation and the whole experiment has been performed under pressure ∼10 -3 Torr in stainless steel vacuum chamber. The minimum and maximum energy of carbon ions observed are 0.2 KeV to 250 KeV respectively.

  8. Diode-pumped passively mode-locked Nd:LuVO4 laser with LT-In0.25Ga0.75As saturable absorber

    International Nuclear Information System (INIS)

    Li, T; Zhao, S; Li, Y; Zhuo, Z; Yang, K; Li, G; Li, D; Yu, Z


    A diode pumped passively mode-locked Nd:LuVO 4 laser with a low temperature (LT) In 0.25 Ga 0.75 As absorber is realized in this paper. An In 0.25 Ga 0.75 As single-quantum-well absorber, which is grown by use of the metal-organic chemical-vapor deposition technique, acts as nonlinear absorber and output coupler simultaneously. A special cavity is designed to keep the power density on In 0.25 Ga 0.75 As under its damage threshold. Both the Q-switched and continuous-wave (cw) mode locking operation are experimentally realized. An average output power of 5.9 W with pulse width of 4.9 ps is achieved at the pump power of 22 W, corresponding to an optical conversion efficiency of 26.8%

  9. Experimental investigation of different regimes of mode-locking in a high repetition rate passively mode-locked semiconductor quantum-dot laser. (United States)

    Kéfélian, Fabien; O'Donoghue, Shane; Todaro, Maria Teresa; McInerney, John; Huyet, Guillaume


    We report experimental investigations on a two-section 16-GHz repetition rate InAs/GaAs quantum dot passively mode-locked laser. Near the threshold current, pseudo-periodic Q-switching with complex dynamics is exhibited. Mode-locking operation regimes characterized by different repetition rates and timing jitter levels are encountered up to twice the threshold current. Evolution of the RF spectrum and optical spectrum with current is compared. The different mode-locked regimes are shown to be associated with different spectral and temporal shapes, ranging from 1.3 to 6 ps. This point is discussed by introducing the existence of two different supermodes. Repetition rate evolution and timing jitter increase is attributed to the coupling between the dominant and the secondary supermodes.

  10. High-efficency stable 213-nm generation for LASIK application (United States)

    Wang, Zhenglin; Alameh, Kamal; Zheng, Rong


    213nm Solid-state laser technology provides an alternative method to replace toxic excimer laser in LASIK system. In this paper, we report a compact fifth harmonic generation system to generate high pulse energy 213nm laser from Q-switched Nd:YAG laser for LASIK application based on three stages harmonic generation procedures. A novel crystal housing was specifically designed to hold the three crystals with each crystal has independent, precise angular adjustment structure and automatic tuning control. The crystal temperature is well maintained at ~130°C to improve harmonic generation stability and crystal operation lifetime. An output pulse energy 35mJ is obtained at 213nm, corresponding to total conversion efficiency ~10% from 1064nm pump laser. In system verification tests, the 213nm output power drops less than 5% after 5 millions pulse shots and no significant damage appears in the crystals.

  11. Spectroscopic study of emission coal mineral plasma produced by laser ablation

    International Nuclear Information System (INIS)

    Vera, L P; Pérez, J A; Riascos, H


    Spectroscopic analysis of plasma produced by laser ablation of coal samples using 1064 nm radiation pulses from a Q-switched Nd:YAG on different target under air ambient, was performed. The emission of molecular band systems such as C 2 Swan System (d 3 Π g →a 3 Π u ), the First Negative System N 2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C 2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0,62 eV); the density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines N II, the found values of 1,2 eV and 2,2 x10 18 cm −3 respectively.

  12. Shock waves and cavitation bubbles in water and isooctane generated by Nd:YAG laser: experimental and theoretical results (United States)

    Muller, Milos; Garen, Walter; Koch, Sandra; Marsik, Frantisek; Neu, Walter; Saburov, Eduado


    Temporal evolution of laser generated cavitation bubbles and shock waves were studied. Q-switched Nd-Yag laser pulses at 1064 nm are focused into the liquid. An Imager 3 CCD camera with multi exposure mode allows recording of 10 images with minimal exposure delay of 100 ns and minimal exposure time of 100 ns. Illumination is provided by xenon flash lamp for single exposure (shock wave recording) and by halogen lamp for multi exposure mode (bubble recording). Distilled water and a retrograde fluid, isooctane, have been under investigation to identify the differences in the cavitation process and shock wave propagation. The calculation of the shock wave velocities in water and isooctane are based on image recording at constant exposure time of 100 ns and using laser differential interferometry. Strong differences of bubble oscillation were observed in water and isooctane. Gilmore's model is used for numerical simulation of bubble dynamics.

  13. Investigations on laser induced nickel and titanium plasmas

    International Nuclear Information System (INIS)

    Rahman, M.K.U.; Latif, A.; Bhatti, K.A.; Rafique, M.S.; Yousaf, M.K.


    Experiments were performed to find out plasma parameters for Nickel and Titanium metals which were irradiated in air (1 atm) to produce plasma plume using Q switched Nd: YAG pulsed laser of 1.1 MW, 10 m J, 1064 nm and 9-14 ns. Langmuir probe was used as a diagnostic tool. The signals at different probe voltages were recorded on digital storage oscilloscope. The information carried by the signals was utilized to calculate electron density, electron temperature, Debye's length and number of particles in Debye's sphere. The study shows that the calculated values of these parameters for Nickel and Titanium are different except Debye's length. Plasma parameters strongly depend on probe potentials, material used and ambient conditions. (author)

  14. Diode-side-pumped intracavity frequency-doubled Nd:YAG/BaWO4 Raman laser generating average output power of 3.14 W at 590 nm. (United States)

    Li, Shutao; Zhang, Xingyu; Wang, Qingpu; Zhang, Xiaolei; Cong, Zhenhua; Zhang, Huaijin; Wang, Jiyang


    We report a linear-cavity high-power all-solid-state Q-switched yellow laser. The laser source comprises a diode-side-pumped Nd:YAG module that produces 1064 nm fundamental radiation, an intracavity BaWO(4) Raman crystal that generates a first-Stokes laser at 1180 nm, and a KTP crystal that frequency doubles the first-Stokes laser to 590 nm. A convex-plane cavity is employed in this configuration to counteract some of the thermal effect caused by high pump power. An average output power of 3.14 W at 590 nm is obtained at a pulse repetition frequency of 10 kHz.

  15. Efficient laser emission from cladding waveguide inscribed in Nd:GdVO(4) crystal by direct femtosecond laser writing. (United States)

    Liu, Hongliang; Tan, Yang; Vázquez de Aldana, Javier R; Chen, Feng


    We report on the fabrication of depressed cladding waveguides in Nd:GdVO(4) laser crystal by using femtosecond laser inscription. The cross section of the structure is a circular shape with a diameter of 150 μm. Under the optical pump at 808 nm, the continuous wave (cw) as well as pulsed (Q-switched by graphene saturable absorber) waveguide lasing at 1064 nm has been realized, supporting guidance of both TE and TM polarizations. The maximum output power of 0.57 W was obtained in the cw regime, while the maximum pulse energy of the pulsed laser emissions was up to 19 nJ (corresponding to a maximum average output power of 0.33 W, at a resonant frequency of 18 MHz). The slope efficiencies achieved for the cw and pulsed Nd:GdVO(4) waveguide lasers were as high as 68% and 52%, respectively.

  16. Diode-pumped two-frequency lasers based on c-cut vanadate crystals

    International Nuclear Information System (INIS)

    Sirotkin, A A; Garnov, Sergei V; Zagumennyi, A I; Zavartsev, Yu D; Kutovoi, S A; Vlasov, V I; Shcherbakov, Ivan A


    The luminescent and lasing properties of the neo-dymium ion at the 4 F 3/2 - 4 I 11/2 transition in c-cut vanadate crystals (Nd:YVO 4 , Nd:GdVO 4 , and Nd:Gd 1-x Y x VO 4 ) are studied. Tuning of the laser radiation wavelength (Δλ = 5.4 nm) is demonstrated. Two-frequency laser schemes with the use of a Lyot filter, a Fabry-Perot etalon, and a Brewster prism as spectral selection elements are proposed and experimentally realised. Stable two-frequency lasing of a laser based on the c-cut Nd:GdVO 4 crystal was obtained in the cw, Q-switched (nanosecond pulses), and active acousto-optic mode-locked (picosecond pulses) regimes. (lasers)

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

    Energy Technology Data Exchange (ETDEWEB)

    Colson, J. [University of Vienna, Department of Physical Chemistry, A-1090 Vienna (Austria); Nimmrichter, J. [Austrian Federal Office for the Care of Monuments, Department for Conservation and Restoration, Arsenal, Objekt 15, Tor 4, A-1030 Vienna (Austria); Kautek, W., E-mail: [University of Vienna, Department of Physical Chemistry, A-1090 Vienna (Austria)


    Multilayer polychrome coatings on medieval and Renaissance stone artefacts represent substantial challenges in laser cleaning. Therefore, polychromic models with classical pigments, minium (Pb{sub 2}{sup 2+}Pb{sup 4+}O{sub 4}), zinc white (ZnO), and lead white ((PbCO{sub 3}){sub 2}·Pb(OH){sub 2}) in an acrylic binder, were irradiated with a Q-switched Nd:YAG laser emitting at 532 nm. The studied medieval pigments exhibit strongly varying incubation behaviours directly correlated to their band gap energies. Higher band gaps beyond the laser photon energy of 2.3 eV require more incubative generation of defects for resonant transitions. A matching of the modification thresholds after more than four laser pulses was observed. Laser cleaning with multiple pulsing should not exceed ca. 0.05 J/cm{sup 2} when these pigments coexist in close spatial proximity.

  18. A Study on non-contact measurements of laser-generated lamb waves

    International Nuclear Information System (INIS)

    Jang, Tae Seong; Lee, Jung Ju; Lee, Seung Seok


    Generation and detection of Lamb waves offer an effective non-destructive testing technique that will detect defects quickly and reliably. Lamb waves are generated in a thin plate by Q-switched Nd:YAG pulsed laser. Symmetric and antisymmetric Lamb modes in low-frequency-thickness regime are excited by illuminating a thin plate with an array of laser-generated line sources. The propagation of laser-generated Lamb waves is detected by measuring the out-of-plane displacements in a non-contact manner using the fiber optic Sagnac interferometer and all commercial adaptive reference-beam interferometer. The characteristics of laser-generated Lamb wave due to its frequency are investigated. Fundamental understanding of laser-generated Lamb modes is presented.

  19. A Study of Laser-generated Ultrasound for Evaluation of Thickness Reduction in Piping System

    International Nuclear Information System (INIS)

    Seo, Kyung Chul; Choi, Sang Woo; Lee, Jun Hyun; Kang, Seung Hyun


    In carbon steel pipes of nuclear power plants, local wall thinning may result from erosion-corrosion or FAC(Flow Accelerated Corrosion) damage. Local wall thinning is one of the major causes for the structural fracture of these pipes. Therefore, assessment of local wall thinning due to corrosion is an important issue in nondestructive evaluation for the integrity of nuclear power plants. In this study, laser-generated ultrasound technique was employed to evaluate local wall thinning due to corrosion. Guided waves were generated in the thermoelastic regime using a Q-switched pulsed Nd:YAG laser with an linear array slit. Time-frequency analysis of ultrasonic waveforms using wavelet transform and FRT(Fast Fourier Transform) allowed the identification of generated guided wave modes by comparison with the theoretical dispersion curves. This study shows some experimental results about optimization of generating laser ultrasound using various linear array slits.

  20. Monolithic solid-state lasers for spaceflight (United States)

    Krainak, Michael A.; Yu, Anthony W.; Stephen, Mark A.; Merritt, Scott; Glebov, Leonid; Glebova, Larissa; Ryasnyanskiy, Aleksandr; Smirnov, Vadim; Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth


    A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state lasers.

  1. Emission characteristics of electrically- and optically-pumped single ZnO micro-spherical crystal (United States)

    Nakamura, D.; Shimogaki, T.; Tetsuyama, N.; Fusazaki, K.; Mizokami, Y.; Higashihata, M.; Ikenoue, H.; Okada, T.


    Zinc oxide (ZnO) nano/microstructures have been attractive as the building blocks for the efficient opto-electronic devices in the ultraviolet (UV) region. We have succeeded in growing the ZnO micro/nanosphere by a simple laser ablation in the air, and therefore we have obtained UV lasing from the sphere under optical pumping. Recently, large size of several 10 micrometer ZnO microspheres were grown using Nd:YAG laser without Q-switching, and ZnO microsphere/p-GaN heterojunction were fabricated to obtain the electroluminescence (EL) from the microsphere by electrical pumping. Room-temperature EL in near-UV region with peak wavelength of 400 nm is observed under forward bias.

  2. Chemical Etching, AFM, Laser Damage Threshold, and Nonlinear Optical Studies of Potential Nonlinear Optical Crystal: Bis (L-Glutamine Potassium Nitrate

    Directory of Open Access Journals (Sweden)

    Redrothu Hanumantharao


    Full Text Available A novel semiorganic nonlinear optical crystal bis (L-glutamine potassium nitrate (BGPN grown by slow evaporation technique at ambient temperature. The grown crystal surface has been analyzed by chemical etching and atomic force microscopy (AFM studies. Amplitude parameters like area roughness, roughness average, valley height, valley depth, peak height, and peak valley height were measured successfully from AFM studies. Etching studies were carried out by various solvents like water, methanol and ethanol. The etching study indicates the occurrence of different types of etch pit patterns like striations and steplike pattern. The laser damage threshold energy has been measured by irradiating laser beam using a Q-switched Nd: YAG laser (1064 nm. Second harmonic generation (SHG studies have been performed by famous Kurtz powder technique with reference to standard potassium dihydrogen phosphate single crystals (KDP. It is found from this technique that SHG efficiency of BGPN is in comparison to that of standard KDP crystals.

  3. Experimental study of the effect of Nd:YAG laser on dental hard tissues: comparison between multi-pulse and free-generation emission code

    International Nuclear Information System (INIS)

    Carballosa Amor, A.; Tellez Jimenez, H.; Ponce Flores, E.; Flores Reyes, T.


    The aim of this study is to compare and contrast the morphological changes on dental hard tissue when irradiated with a Nd: YAG laser both on multi-pulse mode, with a Q: Switch of Cr: YAG passive, and on free generation mode. The experimental sample consisted of 6 healthy third molars which were divided equally and randomly between the two emission methods. The depths of each perforation were measured by optical coherence tomography (OCT). It was noted that, despite being less energy in the multi-pulse mode, the first three shots in this achieved deeper cavities than the ones on the free generation mode. Also, less damage to surrounding tissue were obtained on multi-pulse mode. (Author)

  4. Interaction of a pulsed alexandrite laser with hard and soft biological tissue (United States)

    Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.; Watts, David C.


    An alexandrite laser has been used in the fixed-Q and Q-switched modes, at the fundamental and frequency doubled wavelengths on a selection of hard and soft tissue. In an investigation into the potential use of the laser for the removal of deep lying lesions such as cutaneous vascular lesions and tatoos, studies have been carried out to characterize the depth and extent of the laser/tissue interaction in samples of tissue which greatly absorb the 750 nm radiation. The interaction of the laser radiation with extracted teeth was investigated looking at healthy enamel and dentine, and caries. Surface profile measurements of the enamel and dentine before and after irradiation show little physical effect of the laser irradiation, whereas caries appear to be ablated.

  5. Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

    International Nuclear Information System (INIS)

    Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.


    We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films

  6. Dissemination of optical-comb-based ultra-broadband frequency reference through a fiber network. (United States)

    Nagano, Shigeo; Kumagai, Motohiro; Li, Ying; Ido, Tetsuya; Ishii, Shoken; Mizutani, Kohei; Aoki, Makoto; Otsuka, Ryohei; Hanado, Yuko


    We disseminated an ultra-broadband optical frequency reference based on a femtosecond (fs)-laser optical comb through a kilometer-scale fiber link. Its spectrum ranged from 1160 nm to 2180 nm without additional fs-laser combs at the end of the link. By employing a fiber-induced phase noise cancellation technique, the linewidth and fractional frequency instability attained for all disseminated comb modes were of order 1 Hz and 10-18 in a 5000 s averaging time. The ultra-broad optical frequency reference, for which absolute frequency is traceable to Japan Standard Time, was applied in the frequency stabilization of an injection-seeded Q-switched 2051 nm pulse laser for a coherent light detection and ranging LIDAR system.

  7. Development of high time-resolution laser flash equipment for thermal diffusivity measurements using miniature-size specimens

    International Nuclear Information System (INIS)

    Shikama, Tatsuo; Namba, Chusei; Kosuda, Michinori; Maeda, Yukio.


    For measurements of thermal diffusivity of miniature-size specimens heavily irradiated by neutrons, a new Q-switched laser-flash instrument was developed. In the present instrument the time-resolution was improved to 0.1 ms by using a laser-pulse width of 25 ns. The realization of high time-resolution made it possible to measure the thermal diffusivity of thin specimens. It is expected that copper of 0.7 mm thick, and SUS 304 of 0.1 mm could be used for the measurements. In case of ATJ graphite, 0.5 mm thick specimen could be used for the reliable measurement in the temperature range of 300-1300 K. (author)

  8. Determination of pulse energy dependence for skin denaturation from 585nm fibre laser (United States)

    Mujica-Ascencio, S.; Velazquez-Gonzalez, J. S.; Mujica-Ascencio, C.; Alvarez-Chavez, J. A.


    In this paper, simulation and mathematical analysis for the determination of pulse energy from a Q-switched Yb3+-doped fibre laser is required in Port Wine Stain (PWS) treatment. The pulse energy depends on average power, gain, volume, repetition rate and pulse duration. In some treatments such as Selective Photothermolysis (SP), the peak power at the end of the optical fibre and pulse duration can be obtained and modified via a cavity design. For that purpose, a 585nm optical fibre laser full design which considers all of the above besides the average losses through the optical devices proposed for the design and the Ytterbium optical fibre overall gain will be presented.

  9. Analysis of organic vapors with laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nozari, Hadi; Tavassoli, Seyed Hassan [Laser and Plasma Research Institute, Shahid Beheshti University, G. C, 1983963113 Evin, Tehran (Iran, Islamic Republic of); Rezaei, Fatemeh, E-mail: [Department of Physics, K. N. Toosi University of Technology, 15875-4416 Shariati, Tehran (Iran, Islamic Republic of)


    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  10. Cascaded a-cut Nd:YVO4 self-Raman with second-Stokes laser at 1313 nm (United States)

    Xie, Zhi; Duan, Yanmin; Guo, Junhong; Huang, Xiaohong; Yan, Lifen; Zhu, Haiyong


    A diode-end-pumped, acousto-optic Q-switched second-Stokes self-Raman laser at 1313 nm was demonstrated in a common a-cut Nd:YVO4 crystal, with the primary Raman shift of 890 cm-1. At the incident pump power of 17.1 W, the maximum average output power up to 2.51 W and pulse width of 5 ns for second-Stokes were obtained with the pulse repetition frequency of 50 kHz. The slope efficiency and conversion efficiency with respect to the incident pump power are about 23.7% and 14.7%. The efficient output should be attributed to suitable transmittance of the output coupler used.

  11. Tatuajes y su eliminación por láser

    Directory of Open Access Journals (Sweden)

    T. Castro

    Full Text Available La eliminación de los tatuajes con buen resultado cosmético ha sido una inquietud mantenida durante siglos. La introducción del tratamiento láser ha supuesto un avance importante de cara a obtener buenos resultados con mínimos efectos secundarios. En este trabajo se exponen los diferentes tipos de tatuajes con sus características de pigmento, origen, tipos de tratamientos para su eliminación, y entre ellos, la utilización de la tecnología láser, más concretamente de los láseres de emisión en Q-Switch con sus ventajas y limitaciones. Presentamos también los avances y el futuro de la aplicación del láser en el tratamiento de los tatuajes.

  12. The use of holographic techniques for recording high-speed events

    International Nuclear Information System (INIS)

    Stepanov, B.M.; Filenko, Yu.I.

    The metods resulting from studies carried out using the commercial holographic device UIG-I are described. The device is intended for recording and investigating moving scenes and high-speed events by a holographic method. It consists of a quantum generator with a two-stage amplifier whose radiation energy in a single-mode operation is 0.7 J, and pulse width for passive Q-switching is 40nsec. Hologram portrait making was one of the experiments which illustrate the possible applications of the device. Hologram portraits such as group portraits and those that can be reconstructed in white light, were obtained on Micrat BP-2 and Agfa Gevaert plates

  13. Laser micromachining of indium tin oxide films on polymer substrates by laser-induced delamination

    International Nuclear Information System (INIS)

    Willis, David A; Dreier, Adam L


    A Q-switched neodymium : yttrium-aluminium-garnet (Nd : YAG) laser was used to ablate indium tin oxide (ITO) thin films from polyethylene terephthalate substrates. Film damage and partial removal with no evidence of a melt zone was observed above 1.7 J cm -2 . Above the film removal threshold (3.3 J cm -2 ) the entire film thickness was removed without substrate damage, suggesting that ablation was a result of delamination of the film in the solid phase. Measurements of ablated fragment velocities near the ablation threshold were consistent with calculations of velocities caused by stress-induced delamination of the ITO film, except for a high velocity component at higher fluences. Nanosecond time-resolved shadowgraph photography revealed that the high velocity component was a shock wave induced by the rapid compression of ambient air when the film delaminated.

  14. Growth and characterization of 2-Methylimidazolium D-tartrate single crystal (United States)

    Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.


    Single crystal of 2-Methylimidazolium D-tartrate (2MImdT; C8N2O6H12) has been grown by slow evaporation solution growth technique at room temperature using mixed solvents of ethanol and deionized water. Single crystal X-ray diffraction study confirms that 2-Methylimidazolium D-tartrate belongs to monoclinic crystal system with non-centrosymmetric space group P21. The Fourier transform infrared spectrum of 2-Methylimidazolium D-tartrate reveals the presence of methyl and carboxyl functional groups in the compound. The mechanical properties of 2MImdT crystal were studied. The theoretical factor group analysis predicts 168 optical modes in the title compound. The dielectric behavior of 2MImdT crystals was studied at different frequencies and temperatures. Decomposition and melting point of 2MImdT were found using thermal measurements. SHG behavior of the title compound was demonstrated using Q-switched Nd:YAG laser.


    Directory of Open Access Journals (Sweden)

    Abdulhadi K. Judran


    Full Text Available Using laser in modifying the surfaces of various materials is an important topic in the present time. The type of alloy used in this investigation was 6009Al alloy. Laser has been used as inhibitor to reduce the corrosion rate by using Q-switching Nd: YAG Laser (with changing energy of laser and fixing other parameters under laser shock peening (LSP technique for 6009 AA in hydrochloric acid with concentration of 1 M and the immersion time of 30 minutes at room temperature. The corrosion rate was calculated by using the polarization method. The corrosion rate decreased from (0.366 to 0.016 mm/yr before and after using LSP, respectively. Therefore, this study aims to reduce the corrosion rate that occurs in 6009 Al alloy.

  16. Self-seeded single-frequency laser peening method (United States)

    DAne, C Brent; Hackey, Lloyd A; Harris, Fritz B


    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  17. Self-seeded single-frequency solid-state ring laser and system using same (United States)

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.


    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  18. Frequency mixing in boron carbide laser ablation plasmas (United States)

    Oujja, M.; Benítez-Cañete, A.; Sanz, M.; Lopez-Quintas, I.; Martín, M.; de Nalda, R.; Castillejo, M.


    Nonlinear frequency mixing induced by a bichromatic field (1064 nm + 532 nm obtained from a Q-switched Nd:YAG laser) in a boron carbide (B4C) plasma generated through laser ablation under vacuum is explored. A UV beam at the frequency of the fourth harmonic of the fundamental frequency (266 nm) was generated. The dependence of the efficiency of the process as function of the intensities of the driving lasers differs from the expected behavior for four-wave mixing, and point toward a six-wave mixing process. The frequency mixing process was strongly favored for parallel polarizations of the two driving beams. Through spatiotemporal mapping, the conditions for maximum efficiency were found for a significant delay from the ablation event (200 ns), when the medium is expected to be a low-ionized plasma. No late components of the harmonic signal were detected, indicating a largely atomized medium.

  19. In-vivo remission spectroscopy on tattoos and topically applied photosensitizers in man (United States)

    Koenig, Karsten; Beck, Gerd C.; Boehncke, Wolf-Henning; Kaufmann, Roland; Hibst, Raimund


    In-vivo remission spectra of the human skin in the spectral region of 400 nm to 800 nm were recorded using a xenon lamp as an excitation source, a fiberoptical sensor combined with a polychromator, and a multichannel analyzer. The remission of amateur tattoos before and after laser treatment (Q-switched Nd:YAG) was measured and the degree of blanching determined. It was found that the process of blanching proceeds partly reversible. In another study, the time-dependent remission of human skin after topical administration of the photosensitizer Methylene Blue was studied. The additional application of the ceratolytic agent urea promotes the penetration of the thiazine dye. The experimental data were analyzed by the Kubelka Munk theory.

  20. Control of giant pulse duration in neodymium mini lasers with controllable cavity length and pulsed pumping

    International Nuclear Information System (INIS)

    Berenberg, Vladimir A.; Cervantes, Miguel A.; Terpugov, Vladimir S.


    In a solid-state laser incident on aLiNdP4O12 crystal, pumped by a short light pulse, giant pulse oscillation without the use of resonator Q switching is realized. Tuning of the oscillation pulse duration from 2 up to 20 ns is achieved by changing the cavity length from 24 to 3 mm, respectively. Our analysis of this mode of laser radiation is made on the basis of the rate equations. The factors influencing oscillation pulse duration a reinvestigated. It is shown that in a limiting case the minimal value of the pulse duration is limited by only the rate of excitation transfer from the pumping band to the metastable level