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Sample records for repetitively q-switched high-power

  1. High-power passively Q-switched Nd:KGW laser pumped at 877 nm

    Science.gov (United States)

    Huang, K.; Ge, W. Q.; Zhao, T. Z.; Feng, C. Y.; Yu, J.; He, J. G.; Xiao, H.; Fan, Z. W.

    2016-06-01

    In this work, we demonstrate, for the first time, a high-power passively Q-switched Ng-cut Nd3+:KGd(WO4)2/Cr4+:YAG laser pumped at 877 nm. The maximum average output power of ~1.6 W is obtained at the pump power of 5.22 W, when a saturable absorber with 98 % of initial transmission is used. The corresponding pulse energy is up to 16 µJ. The maximum pulse energy of 25.3 µJ is achieved at a repetition rate of 59 kHz, by employing a saturable absorber with 95 % of initial transmission. The corresponding pulse width and average output power are 89.0 ns and 1.5 W, respectively. A careful cavity design and a good thermal management ensure nearly TEM00 output with M 2 ≤ 1.22 within the whole range of operation in both N p and N m directions at 877 nm pump.

  2. High-power Q-switched erbium-ytterbium codoped fiber laser using multiwalled carbon nanotubes saturable absorber

    Science.gov (United States)

    Ab Razak, Mohd Zulhakimi; Saleh, Zatul Saliza; Ahmad, Fauzan; Anyi, Carol Livan; Harun, Sulaiman W.; Arof, Hamzah

    2016-10-01

    Due to an enormous potential of pulsed lasers in applications such as manufacturing, metrology, environmental sensing, and biomedical diagnostics, a high-power and stable Q-switched erbium-ytterbium codoped double-clad fiber laser (EYDFL) incorporating of multiwall carbon nanotubes (MWCNTs) saturable absorber (SA) made based on polyvinyl alcohol (PVA) with a 3∶2 ratio is demonstrated. The SA was fabricated by mixing a dilute PVA solution with an MWCNTs homogeneous solution. Subsequently, the mixture was sonicated and centrifuged to produce a homogeneous suspension that was left to dry at room temperature to form the MWCNTs-PVA film. The SA was formed by inserting the film between a pair of FC/PC fiber connectors. Then, it was integrated into the EYDFL's ring cavity, which uses a 5-m-long erbium-ytterbium codoped fiber (EYDF). The lasing threshold for the Q-switched EYDFL was at 330 mW. At the maximum available pump power of 900 mW, the proposed EYDFL produced Q-switched pulses with a repetition rate of 74.85 kHz, pulsewidth of ˜3.6 μs, and an average output power of about 5 mW. The maximum energy per pulse of ˜85 nJ was obtained at pump power of ˜700 mW with peak power of 21 mW.

  3. High power CW and Q-switched operation of a diode-side-pumped Nd: YAG 1319-nm laser

    Institute of Scientific and Technical Information of China (English)

    Yunfang Wan; Kezhen Han; Yun Wang; Jingliang He

    2008-01-01

    We demonstrated the highly efficient continuous wave(CW)and Q-switched infrared laser from a diodeside-pumped Nd:YAG crystal.A CW output as high as 66 W at 1319 nm was achieved under the pump power of 460 W,corresponding to a coversion efficiency of 14.3%.A maximum average power of 8.9 W of TEM00 mode was obtained in Q-switched operation at the repetition rate of 8 kHz.The performance of the laser considering the thermal lens effect induced by pump power Was also analyzed.

  4. Q-Switched High Power Single Frequency 2 Micron Fiber Laser Project

    Data.gov (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...

  5. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    Science.gov (United States)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  6. High repetition rate Q-switched radially polarized laser with a graphene-based output coupler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lifei; Jin, Chenjie; Qi, Mei; Chen, Xiaoming; Ren, Zhaoyu, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Zheng, Xinliang, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [Department of Physics, Northwest University, Xi' an 710069 (China); Bai, Jintao [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Department of Physics, Northwest University, Xi' an 710069 (China); Sun, Zhipei [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland)

    2014-12-01

    We demonstrate a Q-switched radially polarized all-solid-state laser by transferring a graphene film directly onto an output coupler. The laser generates Q-switched radially polarized beam (QRPB) with a pulse width of 192 ns and 2.7 W average output power. The corresponding single pulse energy is up to 16.2 μJ with a high repetition rate of 167 kHz. The M{sup 2} factor and the polarization purity are ∼2.1 and 96%, respectively. Our QRPB source is a simple and low-cost source for a variety of applications, such as industrial material processing, optical trapping, and microscopy.

  7. High repetition rate passively Q-switched fiber and microchip lasers for optical resolution photoacoustic imaging

    Science.gov (United States)

    Shi, Wei; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Kerr, Shaun; Zemp, Roger J.; Fedosejevs, Robert

    2010-02-01

    Optical-resolution photoacoustic microscopy is a novel imaging technology for visualizing optically-absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, the imaging speed is limited by the scanning speed and the laser pulse repetition rate. Unfortunately, lasers with high-repetition rate and suitable pulse durations and energies are difficult to find. We are developing compact laser sources for this application. Passively Q-switched fiber and microchip lasers with pulse repetition rates up to 300 kHz are demonstrated. Using a diode-pumped microchip laser fiber-coupled to a large mode-area Yb-doped fiber amplifier we obtained 60μJ 1-ns pulses at the frequency-doubled 532-nm wavelength. The pulse-repetition rate was determined by the power of the microchip laser pump source at 808nm and may exceed 10 kHz. Additionally, a passively Q-switched fiber laser utilizing a Yb-doped double-cladding fiber and an external saturable absorber has shown to produce 250ns pulses at repetition rates of 100-300 KHz. A photoacoustic probe enabling flexible scanning of the focused output of these lasers consisted of a 45-degree glass prism in an optical index-matching fluid. Photoacoustic signals exiting the sample are deflected by the prism to an ultrasound transducer. Phantom studies with a 7.5-micron carbon fiber demonstrate the ability to image with optical rather than acoustic resolution. We believe that the high pulse-repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where realtime imaging performance is essential.

  8. LD side-pumped intracavity frequency-doubled high power Nd:YAG green laser based on acousto-optic Q-switch

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng-chuan; FAN Xiu-wei; XUE Lin; CHAI Hong-liang; HE Jing-liang

    2006-01-01

    A highly efficient and high power green laser generated by intracavity frequency doubling of a diode-side pumped Q-switched Nd:YAG laser has been demonstrated. In the simple L-shaped cavity geometry,the maximum green output power of 28.5 W was obtained with a pulse width of 95 ns at a pulse repetition rate of 10 kHz by using a LBO crystal for frequency doubling,corresponding to a conversion efficiency of 11% from diode pump power to pulse green power. At a pulse repetition rate of 1 kHz,6.9 mJ of pulse energy,25 ns of pulse duration and 276 kW of peak power were obtained.

  9. A high repetition rate passively Q-switched microchip laser for controllable transverse laser modes

    Science.gov (United States)

    Dong, Jun; Bai, Sheng-Chuang; Liu, Sheng-Hui; Ueda, Ken-Ichi; Kaminskii, Alexander A.

    2016-05-01

    A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for versatile controllable transverse laser modes has been demonstrated by adjusting the position of the Nd:YVO4 crystal along the tilted pump beam direction. The pump beam diameter-dependent asymmetric saturated inversion population inside the Nd:YVO4 crystal governs the oscillation of various Laguerre-Gaussian, Ince-Gaussian and Hermite-Gaussian modes. Controllable transverse laser modes with repetition rates over 25 kHz and up to 183 kHz, depending on the position of the Nd:YVO4 crystal, have been achieved. The controllable transverse laser beams with a nanosecond pulse width and peak power over hundreds of watts have been obtained for potential applications in optical trapping and quantum computation.

  10. High repetition rate Q-switched Er3+-doped fiber ring laser

    DEFF Research Database (Denmark)

    Sejka, Milan; Poulsen, Christian; Shi, Yuan

    1993-01-01

    In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity......In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity...

  11. Studies on Nd∶YAG Single-pass Amplifiers for High-power Q-switched Laser System

    Institute of Scientific and Technical Information of China (English)

    CAO Sansong(曹三松); ZHANG Xiangyang(张向阳); HUANG Yanlin(黄燕琳); LI Guangrong(李光荣); SU Xinzhi(苏心智)

    2002-01-01

    The output of Nd∶YAG single-pass laser amplifiers is studied analytically and experimentally. Methods of analysis for single-pass Nd∶YAG laser amplifier are presented. A flashlamp-pumped Q-switched Nd∶YAG oscillator/amplifier laser system has been developed with the average output power of 121.5 W.

  12. High-power diode-pumped Q-switched Er3+:YAG single-crystal fiber laser for active imaging system

    CERN Document Server

    Martial, Igor; Balembois, François; Georges, Patrick

    2012-01-01

    We describe an efficient laser emission from a directly grown Er3+:YAG single-crystal fiber that is resonantly pumped using a continuous-wave (CW) laser diode at 1532 nm. In a longitudinal pumping, it emits 12.5 W at 1645 nm with a slope efficiency of 32%, which is the highest ever reported for a directly grown Er:YAG single-crystal fiber laser. Using an off-axis pumping scheme, CW output powers up to 7.3 W can be reached and in Q-switched operation, the laser produces 2 mJ pulses with a duration of 38 ns at the repetition rate of 1 kHz with an M^{2} factor below 1.8. To our knowledge this is the first directly grown Er3+:YAG single-crystal fiber Q-switched laser. In dual-side pumping scheme a laser emission at 1617 nm is achieved with output powers up to 5.7 W representing the highest output power ever achieved by a diode-pumped Er:YAG laser at this wavelength.

  13. A high-power high-stability Q-switched green laser with intracavity frequency doubling using a diode-pumped composite ceramic Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Wang Yu-Ye; Xu De-Gang; Liu Chang-Ming; Wang Wei-Peng; Yao Jian-Quan

    2012-01-01

    We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd:YAG in a straight plano-concave cavity. The temperature distribution in composite ceramic Nd:YAG crystal is numerically analyzed and compared with that of conventional Nd:YAG crystal.By using a composite ceramic Nd:YAG rod and a type-Ⅱ high gray track resistance KTP (HGTR-KTP) crystal,a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz,with a diode-to-green optical conversion of 14.68%,and a pulse width of 162 ns.To the best of our knowledge,both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd:YAG laser to date.The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.

  14. LD-pumped high repetition rate Q-switched Nd:YVO4 laser by using La3Ga5SiO14 single crystal electro-optic modulator

    Institute of Scientific and Technical Information of China (English)

    Chunyu Wang; Huaguo Zang; Xiaoli Li; Yutian Lu; Xiaolei Zhu

    2006-01-01

    A diode-end-pumped electro-optic (EO) Q-switched Nd:YVO4 laser operating at repetition rate of 10 kpps (pulses per second) was reported. A block of La3Ga5SiO14 (LGS) single crystal was used as a Q-switch and the driver was a metal oxide semiconductor field effect transistor (MOS-FET) pulser of high repetition rate and high voltage. At continuous wave (CW) operation, the slope efficiency of the laser was 46%, and maximum optical-to-optical efficiency was 38.5%. Using an output coupler with transmission of 70%, a 10-kpps Q-switched pulse train with 0.4-mJ monopulse energy and 8.2-ns pulse width was achieved, the optical conversion efficiency was around 15%, and the beam quality M2 factor was less than 1.2.

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

    Science.gov (United States)

    Dong, Jun; He, Yu; Zhou, Xiao; Bai, Shengchuang

    2016-03-01

    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.

  16. 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)

    2016-03-31

    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)

  17. 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

    Indian Academy of Sciences (India)

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak

    2010-11-01

    A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.

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

    Science.gov (United States)

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

    2015-11-30

    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.

  19. Study on the output of LD-pumped passively Q-switched subnanosecond microlasers

    Science.gov (United States)

    Cheng, He-jiao; Chen, Hui-min; Ding, Bo-sheng; Cai, De

    2013-09-01

    Caliber mortar projectiles and bombs are now tend to use the laser fuze because of its high accuracy in distance measurement,the strong ability to resist electromagnetic interference, the high angular resolution and the good concealment. Otherwise, the microlaser can bring about some alluring benefits. For instance, it can generate high quality laser beam, which has small divergence angle and high power. So, This paper summarizes some key factors which have impacts on the output of LD-pumped passively Q-switched subnanosecond microlasers, including the initial transmission of the absorber, the reflection of output coupler, the length of the cavity and the radius of the pumping laser beam, and gives the conclusion of the simulation based on the variation of the density of the reversal particle in the resonant cavity derived from the oscillation equation of the LD-pumped passively Q-switched Cr4+:YAG/ Nd:YAG laser, which provides the basis for the design of the passive Q-switched micro lasers which have high power, high repetition frequency and narrow pulse width.

  20. Design concept and performance considerations for fast high power semiconductor switching for high repetition rate and high power excimer laser

    Science.gov (United States)

    Goto, Tatsumi; Kakizaki, Kouji; Takagi, Shigeyuki; Satoh, Saburoh; Shinohe, Takashi; Ohashi, Hiromichi; Endo, Fumihiko; Okamura, Katsuya; Ishii, Akira; Teranishi, Tsuneharu; Yasuoka, Koichi

    1997-07-01

    A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assisted gate-triggered thyristor (MAGT) was incorporated with a single stage magnetic pulse compression circuit (MPC). The MAGT was specially designed to directly replace thyratrons in a power supply for a high repetition rate laser. Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retaining a high blocking voltage and to extremely reduce the transient turn-on power losses, enduring a higher peak current. A maximum peak current density of 32 kA/cm2 and a current density risetime rate di/dt of 142 kA/(cm2×μs) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV-300 A at a repetition rate of 5 kHz, which, coupled with the MPC, was equivalent to the capability of a high power thyratron. A high repetition rate and high power XeCl excimer laser was excited by the power supply. The results confirmed the stable laser operation of a repetition rate of up to 5 kHz, the world record to our knowledge. An average output power of 0.56 kW was obtained at 5 kHz where the shortage of the total discharge current was subjoined by a conventional power supply with seven parallel switching thyratrons, simultaneously working, for the MAGT power supply could not switch a greater current than that switched by one thyratron. It was confirmed by those excitations that the MAGT unit with the MPC could replace a high power commercial thyratron directly for excimer lasers. The switching stability was significantly superior to that of the thyratron in a high repetition rate region, judging from the discharge current wave forms. It should be possible for the MAGT unit, in the future, to directly switch the discharge current within a rise time of 0.1 μs with a magnetic assist.

  1. Q-switched Nd:YAG optical vortex lasers.

    Science.gov (United States)

    Kim, D J; Kim, J W; Clarkson, W A

    2013-12-02

    Q-switched operation of a high-quality Nd:YAG optical vortex laser with the first order Laguerre-Gaussian mode and well-determined helical wavefronts using a fiber-based pump beam conditioning scheme is reported. A simple two-mirror resonator incorporating an acousto-optic Q-switch was employed, along with an etalon and a Brewster plate to enforce the particular helicity of the output. The laser yielded Q-switched pulses with ~250 μJ pulse energy and ~33 ns pulse duration (FWHM) at a 0.1 kHz repetition rate for 5.1 W of absorbed pump power. The handedness of the helical wavefronts was preserved regardless of the repetition rates. The prospects of further power scaling and improved laser performance are discussed.

  2. Q-switched distributed-Bragg-reflector ytterbium laser

    Science.gov (United States)

    Ouslimani, H.; Bastard, L.; Broquin, J.-E.

    2013-03-01

    A passively Q-switched distributed-Bragg-reflector laser made in glass integrated optics technology, and operating around 1030 nm, is designed, realized and investigated. The laser is formed by an ion-exchanged single mode waveguide realized in an Ytterbium doped phosphate glass. The Q-switching behavior is obtained by hybridizing a saturable absorber film on the waveguides. This allows the realization of a short and simple laser cavity having both pulsed and a narrow linewidth emission. Its experimental characterization leads to the observation of a stable repetition rate of 12.5 kHz and a stable pulse duration of 9.2 ns FWHM.

  3. A High Power and High Repetition Rate Modelocked Ti-Sapphire Laser for Photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    J. Hansknecht; M. Poelker

    2001-07-01

    A high power cw mode-locked Ti-sapphire laser has been constructed to drive the Jefferson Lab polarized photoinjector and provide > 500 mW average power with 50 ps pulsewidths at 499 MHz or 1497 MHz pulse repetition rates. This laser allows efficient, high current synchronous photoinjection for extended periods of time before intrusive steps must be taken to restore the quantum efficiency of the strained layer GaAs photocathode. The use of this laser has greatly enhanced the maximum high polarization beam current capability and operating lifetime of the Jefferson Lab photoinjector compared with previous performance using diode laser systems. A novel modelocking technique provides a simple means to phase-lock the optical pulse train of the laser to the accelerator and allows for operation at higher pulse repetition rates to {approx} 3 GHz without modification of the laser cavity. The laser design and characteristics are described below.

  4. Modelling of graphene Q-switched Tm lasers

    Science.gov (United States)

    Yasukevich, A. S.; Loiko, P.; Gusakova, N. V.; Serres, J. M.; Mateos, X.; Yumashev, K. V.; Kuleshov, N. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2017-04-01

    We report on a model of diode-pumped Thulium lasers passively Q-switched by a graphene saturable absorber applicable also for any other ;fast; saturable absorber. It reasonably predicts the dependence of the pulse duration, pulse energy and pulse repetition frequency on the absorbed power. The model is applied in the present work for a Tm: KLuW microchip laser passively Q-switched with a multi-layer graphene saturable absorber. The laser generates 1 W at 1926 nm with a slope efficiency of 39%. Stable 190 ns /4.1 μJ pulses are achieved at a pulse repetition frequency of 260 kHz. The potential of graphene for the generation of few-ns pulses at 2 μm is discussed.

  5. Diode-Pumped Nanosecond Pulsed Laser with Pulse-Transmission-Mode Q-Switch

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; HUO Yu-Jing; HE Shu-Fang; FENG Li-Chun

    2001-01-01

    Q-switched pulses at 1.064μm with a peak power of 5.02kW and a pulse width of2.8ns were obtained which were pumped by a 1 W laser diode on the Nd:YVO4 microchip at the 1 kHz repetition rate. These values were achieved by combining the techniques of aconsto-optic Q-switching and electro-optic pulse-transmission-mode Q-switching. The temporal characteristics of the pulses were analysed numerically. The experimental results are shown to be in good agreement with theoretical predictions.

  6. A Q-switched, mode-locked fiber laser employing subharmonic cavity modulation.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Lee, Ju Han

    2011-12-19

    We present a new and simple approach for the generation of Q-switched, mode-locked pulses from a laser cavity. The approach is based on cavity loss modulation that employs a subharmonic frequency of the fundamental intermode frequency spacing. A range of experiments have been carried out using an erbium-doped fiber-based ring cavity laser in order to verify that this simple approach can readily produce high quality Q-switched, mode-locked pulses. An active tuning of the Q-switched envelope repetition rate is also shown to be easily achievable by adjusting the order of the applied subharmonic frequency.

  7. Colour centre LiF:F{2/s-} passive Q-switch for cw pumped Nd:Yag laser

    Science.gov (United States)

    Gusev, A. A.; Kubeček, V.; Sochor, V.; Kubelka, J.

    1987-06-01

    Operation of a cw pumped Nd:YAG laser Q-switched by a LiF crystal containing F{2/s-} centres is reported. Pulses of duration of 230 ns with a repetition rate of 1 3 kHz were generated. The colour centre Q-switch was used for the period of three months without any observable deterioration.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun Wan; Young Choi, Sun; Jun Ahn, Kwang; Yeom, Dong-Il, E-mail: diyeom@ajou.ac.kr, E-mail: rotermun@ajou.ac.kr; Rotermund, Fabian, E-mail: diyeom@ajou.ac.kr, E-mail: rotermun@ajou.ac.kr [Department of Energy Systems Research and Department of Physics, Ajou University, 443-749 Suwon (Korea, Republic of); Aravazhi, Shanmugam; Pollnau, Markus [Integrated Optical Micro Systems Groups, MESA+ Institute of Nanotechnology, University of Twente, 7500 AE Enschede (Netherlands); Griebner, Uwe; Petrov, Valentin [Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin (Germany); Bae, Sukang [Soft Innovative Materials Research Center, Korea Institute of Science and Technology, Jeonbuk 565-905 (Korea, Republic of)

    2015-01-15

    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 a 2.4-cm-long waveguide laser operating near 1027 nm. Average output powers up to 34 mW and pulse durations as short as 349 ns are achieved. The measured output beam profile, clearly exhibiting a single mode, agrees well with the theoretically calculated mode intensity distribution inside the waveguide. As the pump power is increased, the repetition rate and pulse energy increase from 191 to 607 kHz and from 7.4 to 58.6 nJ, respectively, whereas the pulse duration decreases from 2.09 μs to 349 ns.

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

    Directory of Open Access Journals (Sweden)

    Jun Wan Kim

    2015-01-01

    Full Text Available 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 a 2.4-cm-long waveguide laser operating near 1027 nm. Average output powers up to 34 mW and pulse durations as short as 349 ns are achieved. The measured output beam profile, clearly exhibiting a single mode, agrees well with the theoretically calculated mode intensity distribution inside the waveguide. As the pump power is increased, the repetition rate and pulse energy increase from 191 to 607 kHz and from 7.4 to 58.6 nJ, respectively, whereas the pulse duration decreases from 2.09 μs to 349 ns.

  10. Dual-kind Q-switching of erbium fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Barmenkov, Yuri O., E-mail: yuri@cio.mx; Kir' yanov, Alexander V. [Centro de Investigaciones en Optica, Loma del Bosque 115, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Cruz, Jose L.; Andres, Miguel V. [Department of Applied Physics and Electromagnetism, University of Valencia, Dr. Moliner 50, Burjassot 46100 (Spain)

    2014-03-03

    Two different regimes of Q-switching in the same implementation of an actively Q-switched erbium-doped fiber laser are demonstrated. Depending on the active fiber length and repetition rate of an intracavity Q-cell (acousto-optic modulator), the laser operates either in the regime of common, rather long and low-power, pulses composed of several sub-pulses or in the one of very short and powerful stimulated Brillouin scattering-induced pulses. The basic physical reason of the laser system to oscillate in one of these two regimes is the existence or absence of CW narrow-line “bad-cavity” lasing in the intervals when the Q-cell is blocked.

  11. All solid-state high power microwave source with high repetition frequency.

    Science.gov (United States)

    Bragg, J-W B; Sullivan, W W; Mauch, D; Neuber, A A; Dickens, J C

    2013-05-01

    An all solid-state, megawatt-class high power microwave system featuring a silicon carbide (SiC) photoconductive semiconductor switch (PCSS) and a ferrimagnetic-based, coaxial nonlinear transmission line (NLTL) is presented. A 1.62 cm(2), 50 kV 4H-SiC PCSS is hard-switched to produce electrical pulses with 7 ns full width-half max (FWHM) pulse widths at 2 ns risetimes in single shot and burst-mode operation. The PCSS resistance drops to sub-ohm when illuminated with approximately 3 mJ of laser energy at 355 nm (tripled Nd:YAG) in a single pulse. Utilizing a fiber optic based optical delivery system, a laser pulse train of four 7 ns (FWHM) signals was generated at 65 MHz repetition frequency. The resulting electrical pulse train from the PCSS closely follows the optical input and is utilized to feed the NLTL generating microwave pulses with a base microwave-frequency of about 2.1 GHz at 65 MHz pulse repetition frequency (prf). Under typical experimental conditions, the NLTL produces sharpened output risetimes of 120 ps and microwave oscillations at 2-4 GHz that are generated due to damped gyromagnetic precession of the ferrimagnetic material's axially pre-biased magnetic moments. The complete system is discussed in detail with its output matched into 50 Ω, and results covering MHz-prf in burst-mode operation as well as frequency agility in single shot operation are discussed.

  12. Q-Switched Thulium-Doped Domestic Silica Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    HU Hui; DU Ge-Guo; YAN Pei-Guang; ZHAO Jun-Qing; GUO Chun-Yu; RUAN Shuang-Chen

    2011-01-01

    We report a cladding-pumped Tm3+-doped domestic silica fiber laser operated at 2μm and actively Q-switched with an acousto-optic modulator. Pulse trains are obtained as pumped by a 785nm laser diode. The maximum average output power is 1.27 W. Peak power up to 4.2 kW and pulse energy up to 840 μJ are obtained with the pulse duration of 200ns produced at a repetition rate of 1 kHz. The laser performance is studied under different repetition rates and pump powers. Lastly, we give some discussion.%@@ We report a cladding-pumped Tm3+-doped domestic silica fiber laser operated at 2pm and actively Q-switched with an acousto-optic modulator.Pulse trains are obtained as pumped by a 785nm laser diode.The maximum average output power is 1.27W.Peak power up to 4.2kW and pulse energy up to 840μJ are obtained with the pulse duration of 200ns produced at a repetition rate of 1 kHz.The laser performance is studied under different repetition rates and pump powers.Lastly, we give some discussion.

  13. Efficient in-band diode-pumped Q-switched solid state laser for methane detection Project

    Data.gov (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...

  14. Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

    Institute of Scientific and Technical Information of China (English)

    Anting Wang(王安廷); Meishu Xing(邢美术); Hai Ming(明海); Jianping Xie(谢建平); Lixin Xu(许立新); Wencai Huang(黄文财); Liang Lü(吕亮); Xiyao Chen(陈曦曜); Feng Li(李锋); Yunxia Wu(吴云霞)

    2003-01-01

    The band-pass characteristic of fiber grating Michelson interferometer is analyzed, which acts as both band-pass filter and Q-switch. An erbium-doped fiber ring laser based on fiber grating Michelson interferometer is implemented for producing single longitudinal mode CW operation with 5 MHz spectral linewidth and up to 6 mW output power. In Q-switched operation, stable fiber laser output pulses with repetition rate of 800 Hz, pulse width of 0.6μs, average power of 1.8 mW and peak power of 3.4 W are demonstrated. The peak power and average power of the Q-switched pulses are varied with the repetition rate.

  15. Doubly active Q switching and mode locking of an all-fiber laser.

    Science.gov (United States)

    Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, Jose L; Andrés, Miguel V

    2009-09-15

    Simultaneous and independent active Q switching and active mode locking of an erbium-doped fiber laser is demonstrated using all-fiber modulation techniques. A magnetostrictive rod attached to the output fiber Bragg grating modulates the Q factor of the Fabry-Perot cavity, whereas active mode locking is achieved by amplitude modulation with a Bragg-grating-based acousto-optic device. Fully modulated Q-switched mode-locked trains of optical pulses were obtained for a wide range of pump powers and repetition rates. For a Q-switched repetition rate of 500 Hz and a pump power of 100 mW, the laser generates trains of 12-14 mode-locked pulses of about 1 ns each, within an envelope of 550 ns, an overall energy of 0.65 microJ, and a peak power higher than 250 W for the central pulses of the train.

  16. Compact Narrow Linewidth Actively Q-Switched Er–Yb Double-Clad Fiber Laser

    Directory of Open Access Journals (Sweden)

    Berenice Posada-Ramírez

    2017-06-01

    Full Text Available Actively Q-switched laser operation of a narrow linewidth compact fiber laser based on an Er–Yb double-clad fiber is presented. The laser linewidth as a function of the repetition rate and the Q-switched pulses characteristics for different pump powers are experimentally analyzed. Stable Q-switched laser operation with spectral laser linewidth of 73 pm in a repetition rate range from 90 to 270 kHz is obtained. The minimum pulse duration of 178 ns, maximum peak power of 30.5 W, and maximum pulse energy of 5.4 µJ are observed. The maximum average power reached is 1.1 W.

  17. Q-Switching in a Neodymium Laser

    Science.gov (United States)

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

    2012-01-01

    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…

  18. Optimization of erbium-doped actively Q-switched fiber laser implemented in symmetric configuration

    OpenAIRE

    Kolpakov, Stanislav A.; Sergeyev, Sergey; Mou, Chengbo; Neil T. Gordon; Zhou, Kaiming

    2014-01-01

    We report the results of an experimental study aimed at improving the performance of actively Q-switched fiber lasers. Unlike generic design schemes employing photonic crystal fibers, largemodal diameter fibers or double-clad fibers, we demonstrate a high-power, actively Q-switched laser based on standard com- munication erbium doped fibers with peak irradiance beyond the state-of-the-art at 3.1 GW/cm2 . The laser had 2.2 kW peak power, 15.5 ns pulse duration and 36.8 µJ pulse energy. We have...

  19. Q-switched Ho:Lu2O3 laser at 2.12 μm.

    Science.gov (United States)

    Lamrini, Samir; Koopmann, Philipp; Scholle, Karsten; Fuhrberg, Peter

    2013-06-01

    We report on a Q-switched Ho:Lu2O3 laser resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The maximum output energy extracted from the compact plano-plano acousto-optically Q-switched resonator was 8 mJ at a 100 Hz pulse repetition rate, while the peak power was 40 kW. The laser wavelength was 2.124 μm.

  20. Passively Q-switched Nd:GdTaO4 laser by graphene oxide saturable absorber

    Science.gov (United States)

    Zhang, Bingyuan; Song, Qi; Wang, Guoju; Gao, Yajing; Zhang, Qingli; Wang, Minghong; Wang, Wenjun

    2016-08-01

    We experimentally demonstrated a laser diode-pumped Q-switched Nd:GdTaO4 crystal laser at 1066 nm using a multilayer graphene oxide as the saturable absorber (GOSA). The GOSA is fabricated by transferring the liquid-phase-exfoliated GO nanosheets onto a K9 glass substrate. When the GOSA was inserted into the plano-plano laser cavity, a stable Q-switched laser operation is achieved with a maximum average output power of 0.382 W and repetition rate of 362 kHz. The shortest pulse duration is 194 ns and the single pulse energy is about 1.05 μJ.

  1. Linearly polarized intracavity passive Q-switched Yb-doped photonic crystal fibre laser

    Indian Academy of Sciences (India)

    Usha Chakravarty; Antony Kuruvilla; Rajpal Singh; B N Upadhyay; K S Bindra; S M Oak

    2014-02-01

    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% was achieved. Measured polarization extinction ratio (PER) of the Q-switched laser output was 10.5 dB.

  2. Q-switching with single crystal photo-elastic modulators

    Science.gov (United States)

    Bammer, F.; Petkovsek, R.

    2011-02-01

    An overview is given about experiments with a new method for Q-switching lasers at a constant pulse repetition frequency. It uses inside the laser resonator a Single Crystal Photo-Elastic Modulator (SCPEM). This consists of one piezo-electric crystal electrically excited on a mechanical resonance frequency. In resonance mechanical stresses are induced that lead via the photo-elastic effect to a strongly modulated birefringence. Polarized light going through such an oscillating crystal will experience a significant modulation of its polarization and of transmission through a polarizer. Suitable materials should not be optically active, as it is for example the case for SiO2, and should allow the excitation of a longitudinal oscillation with an electric field perpendicular to the travelling direction of the light. Crystals of the group 3m, like LiTaO3 and LiNbO3, proved to be ideally suited for SCPEMS for the NIR- and VIS-region. For the infrared GaAs can be used. We demonstrated SCPEM-Q-switching for a Nd:YAG-fiber, a Nd:YVO4-slab- and a Nd:YAG-rod-laser with typical pulse repetition rates of 100-200kHz, pulse enhancement factors of 100 and pulse durations {1/100 of the period time. Typically the average power during pulsed operation is nearly the same as the cw-power, when the modulator is switched off. The most stable results were achieved up to now with the Nd:YVO4-slab-laser at 10W average power, 1.1 kW peak power, 127 kHz pulse repetition rate, and 70ns pulse durations.

  3. Erbium-doped CW and Q-switched fiber ring laser with fiber grating Michelson interferometer

    Science.gov (United States)

    Wang, Anting; Ming, Hai; Xie, Jianping; Xu, Lixin; Huang, Wencai; Lv, Liang; Chen, Xiyao; Li, Feng; Wu, Yunxia; Xing, Meishu

    2003-01-01

    The band-pass characteristic of fiber grating Michelson interferometer is analyzed, which acts as both band-pass filter and Q-switch. An erbium-doped fiber ring laser based on fiber grating Michelson interferometer is implemented for producing single longitudinal mode CW operation with 5 MHz spectral linewidth and up to 6 mW output power. In Q-switched operation, stable fiber laser output pulses with repetition rate of 800 Hz, pulse width of 0.6 ?s, average power of 1.8 mW and peak power of 3.4 W are demonstrated. The peak power and average power of the Q-switched pulses are varied with the repetitionrate.

  4. Q-switched and Mode-locked Characteristics of Cr4+:YAG Crystal

    Institute of Scientific and Technical Information of China (English)

    TIAN Wen-miao; YANG Feng; GAO Li-yan; WANG Guang-gang; LIU Shi-hua; LIU Jie

    2006-01-01

    The passively Q-switched and mode-locked(QML) characteristics in a diode-pumped Nd:GdVO4 laser with Cr4+:YAG saturable absorbers have been demonstrated. A maximum average output power of 710 mW has been obtained in the QML laser. The maximum energy of a single Q-switched pulse is 52.5 μJ,with the corresponding pulse width of 30 ns and the peak power of 1.75 kW,at the incident pump power of 7.75 W. The repetition rates of the Q-switched envelope and the mode-locked laser pulse are 16.7 kHz and 680 MHz,respectively.

  5. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating.

    Science.gov (United States)

    Pérez-Millán, P; Díez, A; Andrés, M; Zalvidea, D; Duchowicz, R

    2005-06-27

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  6. Graphene Q-switched Tm:KY(WO4)2 waveguide laser

    Science.gov (United States)

    Kifle, E.; Mateos, X.; Loiko, P.; Yumashev, K.; Yasukevich, A.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2017-04-01

    We report on the first Tm3+-doped double tungstate waveguide laser passively Q-switched by a graphene saturable absorber using a 12.4 µm-thick 3 at.% Tm:KY0.58Gd0.22Lu0.17(WO4)2 epitaxial layer grown on a (0 1 0)-oriented pure KY(WO4)2 substrate. This laser generated 5.8 nJ/195 ns pulses at 1831.8 nm corresponding to a pulse repetition frequency of 1.13 MHz. These are the shortest pulses achieved in passively Q-switched Tm waveguide lasers. The laser slope efficiency was 9% and the Q-switching conversion efficiency reached 45%. Graphene is promising for the generation of ns pulses at ~2 µm in Tm3+-doped double tungstate waveguide lasers operating in the MHz-range.

  7. Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating

    Science.gov (United States)

    Pérez-Millán, P.; Díez, A.; Andrés, M. V.; Zalvidea, D.; Duchowicz, R.

    2005-06-01

    We report an actively Q-switched all-fiber laser based on magnetostriction modulation of a Bragg grating. The laser employs a pair of Bragg gratings as reflective mirrors, one of which is bonded to a magnetostrictive element. Lengthening of the magnetostrictive element when a magnetic field is applied shifts the Bragg wavelength of the grating, allowing control of the Q-factor of the cavity and, thus, performing active Q-switching. The magnetostrictive modulator is small, compact and requires less than 300 mW electrical drive power. Using erbium-doped fiber and a maximum pump power of 120 mW, Q-switch pulses of more than 1 W peak power were obtained, with a pulse repetition rate that can be continuously varied from 1 Hz to 125 kHz.

  8. 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: xulixin@ustc.edu.cn; 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)

    2015-11-09

    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.

  9. Optimizing drive parameters of a nanosecond, repetitively pulsed microdischarge high power 121.6 nm source

    Science.gov (United States)

    Stephens, J.; Fierro, A.; Trienekens, D.; Dickens, J.; Neuber, A.

    2015-02-01

    Utilizing nanosecond high voltage pulses to drive microdischarges (MDs) at repetition rates in the vicinity of 1 MHz previously enabled increased time-averaged power deposition, peak vacuum ultraviolet (VUV) power yield, as well as time-averaged VUV power yield. Here, various pulse widths (30-250 ns), and pulse repetition rates (100 kHz-5 MHz) are utilized, and the resulting VUV yield is reported. It was observed that the use of a 50 ns pulse width, at a repetition rate of 100 kHz, provided 62 W peak VUV power and 310 mW time-averaged VUV power, with a time-averaged VUV generation efficiency of ˜1.1%. Optimization of the driving parameters resulted in 1-2 orders of magnitude increase in peak and time-averaged power when compared to low power, dc-driven MDs.

  10. A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source

    Science.gov (United States)

    Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de

    2017-06-01

    A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

  11. High power, high repetition rate, few picosecond Nd:LuVO₄ oscillator with cavity dumping.

    Science.gov (United States)

    Gao, Peng; Guo, Jie; Li, Jinfeng; Lin, Hua; Yu, Haohai; Zhang, Huaijin; Liang, Xiaoyan

    2015-12-28

    We investigate the potential use of Nd:LuVO4 in high average power, high repetition rate ultrafast lasers. Maximum mode-locked average power of 28 W is obtained at the repetition rate of 58 MHz. The shortest pulse duration is achieved at 4 ps without dispersion compensation. With a cavity dumping technique, the pulse energy is scaling up to 40.7 μJ at 300 kHz and 14.3 μJ at 1.5 MHz.

  12. Graphene thickness-dependent Er-doped Q-switched optical fiber laser

    Science.gov (United States)

    Wang, Xiaolong; Sang, Mei; Zhu, Pan; Liu, Ke; Yang, Tianxin

    2013-02-01

    A stable Q-switched laser is useful in the area of remote sensing, range finding, optical imaging, material processing, and fiber communications. With its excellent linear and nonlinear optical characteristics, graphene has been proven to be an attractive material to generate nanosecond, picosecond and femtosecond laser pulses. It has a lot of advantages, such as lower saturation intensity, larger saturable-absorption modulation depth, higher damage threshold, sub-picosecond recovery time and an ultrabroad wavelength-independent saturable-absorption range. In this paper, we demonstrate a graphene based Q-switched fiber laser. Graphene was deposited on the fiber interface by the optically driven deposition method. The thickness of the graphene can be controlled by changing depositing time. The compact Q-switched erbium-doped fiber laser based on graphene operated stably, and got Q-switched pulse sequences output with the repetition rate of 19KHz and the average power of 1.4mW when pump power is 40mW. Higher peak power, shorter pulse duration, and higher repetition rate could be achieved by adjusting the thickness of the graphene layer appropriately. Besides, the pulse duration and output power is proved to be a function of the pump power. The repetition rate of this fiber laser had a characteristic of monotonically increasing, near-linear with the changing of pump power. The stable Q-switching pulse output can be observed on the oscilloscope with differently specific repetition rate and pump power. Theory analysis of this fiber laser and further improvement methods is also studied combined with the experimental results.

  13. Radially polarized and passively Q-switched Nd:YAG laser with composite structure of gain medium

    Institute of Scientific and Technical Information of China (English)

    Kegui Xia; Jianlang Li

    2011-01-01

    We report on a radially polarized and passively Q-switched Nd:YAG/Cr4+:YAG laser.The bulk Nd:YAG crystal is bonded with two undoped YAG crystal end caps to weaken the thermal lens effect and thus,enhance the extraction of stored energy in the bulk gain material.In the absence of active water cooling,the average laser power reaches 383 mW with 33% slope efficiency,and the laser pulse achieves 1.457-W peak power,18.9-ns duration,and 13.9-kHz repetition rate with 97.6% polarization purity.The radially polarized laser beam shows axial symmetry both in amplitude and polarization[1-3].The beam is applied in a variety of fields[3-8] such as particle trapping and acceleration[5],high-resolution microscopy[6],and material processing (e.g.,metal cutting or drilling).Because radially polarized light is globally of the ptype with respect to the cutting surface,the material absorption to the irradiation could be maximized,the significant effect of the cutting depth and cutting speed can be facilitated[7,8].This advantage has created a high demand for high power and radially polarized lasers.%We report on a radially polarized and passively Q-switched Nd:YAG/Cr4+:YAG laser. The bulk Nd:YAC crystal is bonded with two undoped YAG crystal end caps to weaken the thermal lens effect and thus, enhance the extraction of stored energy in the bulk gain material. In the absence of active water cooling, the average laser power reaches 383 mW with 33% slope efficiency, and the laser pulse achieves 1.457-W peak power, 18.9-ns duration, and 13.9-kHz repetition rate with 97.6% polarization purity.

  14. Dual-loss-modulated Q-switched Tm:LuAG laser with AOM and monolayer graphene.

    Science.gov (United States)

    Luan, Chao; Yang, Ke Jian; Zhao, Jia; Zhao, Sheng Zhi; Qiao, Wen Chao; Li, Tao; Feng, Tian Li; Liu, Cheng; Qiao, Jun Peng; Zheng, Li He; Xu, Jun; Wang, Qing Guo; Su, Liang Bi

    2015-09-20

    A laser-diode-pumped dual-loss-modulated Q-switching Tm:LuAG laser with an acousto-optic modulator (AOM) and monolayer graphene saturable absorber (SA) around 2 μm is presented for the first time to the best of our knowledge. The average output power and the pulse widths for different repetition rates have been measured. In comparison with the singly Q-switching laser with AOM or with monolayer graphene SA, the dual-loss-modulated Q-switching laser could generate shorter pulse width and higher peak power. The maximum pulse width compression ratio was found to be 3.11, and the highest peak power was enhanced 97.4 times. The experimental results show that the dual-loss-modulated technology is an efficient method for compressing the pulse width, improving the peak power, and enhancing the pulse stability for the Q-switched lasers at 2 μm.

  15. Optical Fiber Pumped High Repetition Rate and High Power Nd:YVO4 Picosecond Regenerative Amplifier

    Directory of Open Access Journals (Sweden)

    Zhen-Ao Bai

    2015-08-01

    Full Text Available We report a stable optical fiber pumped Nd:YVO4 all solid state regenerative amplifier with all fiber picosecond laser as seed source. 888 nm Yb optical fiber lasers was chosen as pump source to reduce quantum defect for improved thermal performance. At the repetition rate of 99.6 kHz, maximum power of 19.63 W with 36 ps pulse duration were achieved when seeded by a 150 mW picosecond oscillator. The wavelength delivered was 1064.07 nm with spectral width of 0.14 nm.

  16. Temporal synchronization and spectral combining of pulses from fiber lasers Q-switched by independent MEMS micro-mirrors.

    Science.gov (United States)

    Fabert, Marc; Desfarges-Berthelemot, Agnès; Kermène, Vincent; Crunteanu, Aurelian

    2012-09-24

    We present what we believe to be the first demonstration of spectral combining of multiple fiber lasers Q-switched by independent micro-electro-mechanical system (MEMS). By correlating the actuation of the individual MEMS devices, the associated Q-switched lasers can be operated in either synchronous or asynchronous modes in such a way that their overall combined output may result in high energy emission pulses or in laser emission with higher pulse repetition rate. In a proof-of-principle experiment, we demonstrate the combination of four individual Q-switched lasers (each of them operating at 20 kHz repetition rate) leading to a final laser system generating pulses with a repetition rate of 80 kHz.

  17. A reliable, compact, and repetitive-rate high power microwave generation system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei; Li, Zhi-qiang; Sun, Xiao-liang; Zhang, Jun [College of Optoelectronics Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

    2015-11-15

    A compact high power microwave (HPM) generation system is described in this paper. The main parts of the HPM system are a Marx generator with a pulse forming line and a magnetron with diffraction output. The total weight and length of the system are 250 kg and 120 cm, respectively. The output microwave power of the HPM system at 550 kV of applied voltage and 0.33 T of magnetic field reaches 1 GW at 2.32 GHz of central frequency with 38 ns of pulse duration, 23% of power conversion efficiency, and Gaussian radiation pattern. In the bursts operation, both time and amplitude jitters are less than 4 ns and lower than 1.5 dB, respectively.

  18. High-power, high repetition-rate, green-pumped, picosecond LBO optical parametric oscillator.

    Science.gov (United States)

    Kienle, Florian; Teh, Peh Siong; Lin, Dejiao; Alam, Shaif-Ul; Price, Jonathan H V; Hanna, D C; Richardson, David J; Shepherd, David P

    2012-03-26

    We report on a picosecond, green-pumped, lithium triborate optical parametric oscillator with record-high output power. It was synchronously pumped by a frequency-doubled (530 nm), pulse-compressed (4.4 ps), high-repetition-rate (230 MHz), fiber-amplified gain-switched laser diode. For a pump power of 17 W, a maximum signal and idler power of 3.7 W and 1.8 W was obtained from the optical parametric oscillator. A signal pulse duration of ~3.2 ps was measured and wide tunability from 651 nm to 1040 nm for the signal and from 1081 nm to 2851 nm for the idler was achieved.

  19. High power microwave generation using a repetitive electron gun with a ferroelectric cathode

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Y.; Ivers, J.D.; Nation, J.A.; Wang, P. Golkowski, C.; Flechtner, D.; Schaechter, L.

    1999-07-01

    An electron gun using a ferroelectric cathode driven by a ferrite core transformer-pulse line system produces a 500kV, 50--200A, 250ns long beam. The beam is used to drive an X-band amplifier. The amplifier consists of a single stage disk loaded type structure. At the end of the amplifier, a coaxial mode converter is used to decouple the beam from the microwave radiation. The amplifier operates at a repetition rate of 0.1Hz. The beam emission is controlled by a voltage pulse applied to the back of the ferroelectric. Results will be reported on the amplifier performance characteristics with a 50A beam and the results compared with simulation data. An improved gun design, which gives a uniform cross section 200A beam is being built, and early results obtained, using the high current gun, will also be presented.

  20. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    Juan Du(杜鹃); Jingliang He(何京良); Jie Liu(刘杰); Qiuxia Jiang(姜秋霞); Sheng Liu(刘胜); Huitian Wang(王慧田)

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150 kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  1. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    杜鹃; 何京良; 刘杰; 姜秋霞; 刘胜; 王慧田

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  2. An acousto-optic Q-switched fiber laser using China-made double-cladding fiber

    Institute of Scientific and Technical Information of China (English)

    Hongming Zhao; Qihong Lou; Jun Zhou; Fangpei Zhang; Jingxing Dong; Yunrong Wei; Libo Li; Zhijiang Wang

    2007-01-01

    @@ A simple laser-diode pumped acoustic-optic Q-switched fiber laser is reported by using China-made largemode-area ytterbium-doped fiber. Q-switched pulses with a beam quality factor of M2 ≈ 2 and several hundred nanoseconds pulse duration are achieved at the repetition rate of 1 - 50 kHz. When the repetition rate is 1 kHz, the pulse energy is 0.93 mJ with the pulse duration of 132 ns. Meanwhile, the profile of laser pulses shows some mode-locking phenomena, the mechanism of the phenomena is discussed.

  3. High Power Fibre Laser System for a High Repetition Rate Laserwire

    CERN Document Server

    Nevay, L J; Corner, L

    2014-01-01

    We present the development of a high power fibre laser system to investigate its suitability for use in a transverse electron beam profile monitor i.e. a laserwire. A system capable of producing individual pulses up to $165.8 \\pm 0.4 \\mu$J at 1036 nm with a full-width at half-maximum of $1.92 \\pm 0.12$ps at 6.49 MHz is demonstrated using a master oscillator power amplifier design with a final amplification stage in a rod-type photonic crystal fibre. The pulses are produced in trains of 1 ms in a novel burst mode amplification scheme to match the bunch pattern of the charged particles in an accelerator. This method allows pulse energies up to an order of magnitude greater than the steady-state value of $17.0 \\pm 0.6 \\mu$J to be achieved at the beginning of the burst with a demonstrated peak power of $25.8 \\pm 1.7$ MW after compression. The system is also shown to demonstrate excellent spatial quality with an $M^{2} = 1.26 \\pm 0.01$ in both dimensions which would allow nearly diffraction limited focussing to be...

  4. High power fiber laser system for a high repetition rate laserwire

    Directory of Open Access Journals (Sweden)

    L. J. Nevay

    2014-07-01

    Full Text Available We present the development of a high power fiber laser system to investigate its suitability for use in a transverse electron beam profile monitor, i.e., a laserwire. A system capable of producing individual pulses up to 165.8±0.4  μJ at 1036 nm with a full width at half maximum of 1.92±0.12  ps at 6.49 MHz is demonstrated using a master oscillator power amplifier design with a final amplification stage in a rod-type photonic crystal fiber. The pulses are produced in trains of 1 ms in a novel burst mode amplification scheme to match the bunch pattern of the charged particles in an accelerator. This method allows pulse energies up to an order of magnitude greater than the steady-state value of 17.0±0.6  μJ to be achieved at the beginning of the burst with a demonstrated peak power of 25.8±1.7  MW after compression. The system is also shown to demonstrate excellent spatial quality with an M^{2}=1.26±0.01 in both dimensions, which would allow nearly diffraction limited focusing to be achieved.

  5. Hybrid Neodymium-doped passively Q-switched waveguide laser

    Energy Technology Data Exchange (ETDEWEB)

    Salas-Montiel, Rafael [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France); Bastard, Lionel [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France)], E-mail: lionel.bastard@minatec.inpg.fr; Grosa, Gregory; Broquin, Jean-Emmanuel [IMEP-LAHC, 3 Parvis Louis Neel BP 257, 38016 Grenoble Cedex 1 (France)

    2008-03-25

    In the mid 80s, the doping of optical fibers' core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by an ion-exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a bis(4-dimethylaminodithiobenzil)nickel (BDN) saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the continuous wave (CW) operation of the laser with an undoped cladding. We show that for a 3.5 {mu}m wide, 1.5 cm long waveguide realized by a silver-sodium ion-exchange, a 6 mW output has been achieved by creating a Fabry-Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN-doped layers are presented. It is shown that a proper selection of the hybrid guiding condition and saturable absorber concentration entail a non-saturated excess absorption of 3.4 dB/cm. Finally, we present the results we obtained on the Q-switched behaviour of the laser. Indeed a repetition rate of 330 kHz is achieved for a pulse energy of 10 nJ and a peak power of 1 W.

  6. Self-Q-switched Cr:LiCAF laser

    OpenAIRE

    Beyatlı, Ersen; Sennaroğlu, Alphan; Demirbaş, Ümit

    2013-01-01

    We report self-Q-switched operation of a Cr:LiCAF laser for the first time to our knowledge. Self-Q-switching (SQS) refers to the generation of a periodic train of Q-switched pulses from a laser cavity containing only the gain medium. Since SQS does not require any additional elements such as saturable absorbers or active modulators, it is far simpler and lower cost in comparison with other Q-switching methods. In the experiments, SQS operation was observed by using an x-shaped, astigmaticall...

  7. All fiber passively Q-switched laser

    Science.gov (United States)

    Soh, Daniel B. S.; Bisson, Scott E

    2015-05-12

    Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

  8. Graphene-based passively Q-switched dual-wavelength erbium-doped fiber laser.

    Science.gov (United States)

    Luo, Zhengqian; Zhou, Min; Weng, Jian; Huang, Guoming; Xu, Huiying; Ye, Chenchun; Cai, Zhiping

    2010-11-01

    We demonstrate a compact Q-switched dual-wavelength 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. Also benefiting from the strong third-order optical nonlinearity of graphene to suppress the mode competition of EDF, a stable dual-wavelength Q-switching operation has been achieved using a two-reflection peak fiber Bragg grating as the external cavity mirror. The Q-switched EDF laser has a low pump threshold of 6.5 mW at 974 nm and a wide range of pulse-repetition rate from 3.3 to 65.9 kHz. The pulse duration and the pulse energy have been characterized. This is, to the best of our knowledge, the first demonstration of a graphene-based Q-switched laser.

  9. S-band Q-switched thulium fluoride fiber laser using graphene saturable absorber

    Science.gov (United States)

    Ahmad, H.; Reduan, S. A.; Hassan, N. A.; Ooi, S. I.; Tiu, Z. C.

    2017-07-01

    A Q-switched S-band thulium fluoride fiber (TFF) driven by a 1400 nm laser diode is proposed and demonstrated. The TFF has the advantage of being pumped at 1400 nm, which is an easily available and relatively low-cost pump source, as opposed to conventional pumping at 1050 nm. It has a gain profile from 1440 nm to 1520 nm, and Q-switching is realized with the use of a thin film graphene saturable absorber. The Q-switched TFF laser exhibits a maximum repetition rate and minimum pulse width of 36.3 kHz and 3.2 µs respectively, as well as an average output power and pulse energy of 0.76 mW and 20.9 nJ at a maximum pump power of 230.4 mW. The output pulses are highly stable, and to the best knowledge of the authors this is the first demonstration of a Q-switched TFF laser pumped at 1400 nm.

  10. Q-switched pulse laser generation from double-cladding Nd:YAG ceramics waveguides.

    Science.gov (United States)

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

    2013-08-12

    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.

  11. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate

    Science.gov (United States)

    Borisov, V. M.; El'tsov, A. V.; Khristoforov, O. B.

    2015-08-01

    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al2O3 ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse-1, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ <= 0.7%) is achieved using an all-solid-state pump system.

  12. 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)

    2015-12-31

    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)

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

    NARCIS (Netherlands)

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

    2015-01-01

    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

  14. LD end-pumped acousto-optic Q-switched 1319 nm/1338 nm dual-wavelength Nd:YAG laser

    Science.gov (United States)

    Wu, C. T.; Yu, M.; Wang, C.; Yu, K.; Yu, Y. J.; Chen, X. Y.; Jin, G. Y.

    2016-10-01

    Laser characteristics of acousto-optic Q-switched operation of 1319 nm/1338 nm dual-wavelength composite Nd:YAG laser were studied. Maximum output power of 5.77 W was achieved in CW operation. Under Q-switched operation, the maximum peak power of 3.96 kW and minimum pulse width of 65.6 ns was obtained at repetition frequency of 20 kHz with the duty ratio of 96%. The influence of the duration of the ultrasonic field acted on the Q-switch to the output characteristics of dual-wavelength composite Nd:YAG laser had been reported first time.

  15. Active Q-switching of a fiber laser using a modulated fiber Fabry-Perot filter and a fiber Bragg grating

    Science.gov (United States)

    Martínez Manuel, Rodolfo; Kaboko, J. J. M.; Shlyagin, M. G.

    2016-02-01

    We propose and demonstrate a simple and robust actively Q-switched erbium-doped fiber ring cavity laser. The Q-switching is based on dynamic spectral overlapping of two filters, namely a fiber Bragg grating-based filter and a fiber Fabry-Perot tunable filter. Using 3.5 m of erbium-doped fiber and a pump power of only 60 mW, Q-switched pulses with a peak power of 9.7 W and a pulse duration of 500 ns were obtained. A pulse repetition rate can be continuously varied from a single shot to a few KHz.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Zhi-Xu; Yao, Chuan-Fei; Kang, Zhe; Qin, Guan-Shi, E-mail: qings@jlu.edu.cn; Qin, Wei-Ping, E-mail: wpqin@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Ohishi, Yasutake [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2014-06-14

    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.

  17. Passively Q-switched Er,Yb:GdAl3(BO3)4 laser with single-walled carbon nanotube based saturable absorber

    Science.gov (United States)

    Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Prudnikova, M. B.; Maltsev, V. V.; Leonyuk, N. I.; Choi, S. Y.; Rotermund, F.; Kuleshov, N. V.

    2017-03-01

    We demonstrate a passively Q-switched Er,Yb:GdAl3(BO3)4 diode-pumped laser emitting near 1.5 µm. By using a single-walled carbon nanotube (SWCNT) as a saturable absorber, Q-switched laser pulses with energy of 0.8 µJ and duration of 130 ns at a maximum repetition rate of 500 kHz were obtained at 1550 nm.

  18. Short pulse diode-pumped Tm:YAG slab laser electro-optically Q-switched by RbTiOPO4 crystal

    Science.gov (United States)

    Jin, Lin; Liu, Pian; Huang, Haitao; Liu, Xuan; Shen, Deyuan

    2016-10-01

    In this paper, a laser diode end pumped RbTiOPO4 (RTP) electro-optically Q-switched Tm:YAG slab laser was demonstrated. Stable Q-switched pulse with the shortest pulse width of 58 ns and an average output power of 7.5 W were realized at the repetition rate of 1 KHz, corresponding to the slope efficiency of 21.7%.

  19. Diode-Pumped Self Q-Switched and Mode-Locking Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Yong; LI Ping-Xue; LI De-Hua; FENG Bao-Hua; FU Pan-Ming; ZHANG Zhi-Guo; ZHANG Shi-Wen

    2004-01-01

    @@ Using Nd3+,Cr4+ : YAG as a laser crystal and saturable absorber simultaneously, we obtain a self-Q-switched and mode-locking laser at 1.06 μm with straight cavity structure. Self mode-locking phenomenon was observed at an intracavity intensity of only about 2000 W/cm2. More than 90% modulation depth is achieved at an intracavity intensity of less than 3.0 × 104 W/cm2 for the first time. The Q-switched pulse width and repetition rate are found to be connected with the cavity length and the output power.

  20. Multi-watt Q-switched Nd:YVO4 laser with GaAs output coupler

    Institute of Scientific and Technical Information of China (English)

    Ping Li(李平); Qingpu Wang(王青圃); Shichen Li(李世忱); Jie Lian(连结); Baomin Ma(马宝民); Jingliang He(何京良)

    2003-01-01

    A passively Q-switched operation of a diode-pumped Nd:YVO4 laser is demonstrated, in which a GaAs film is used as the saturable absorber as well as the output coupler. At the pump power of 10 W, a stable fundamental-mode average power output of 2.11 W was obtained with a pulse duration of 140 ns, pulse energy of 76 μJ and pulse repetition rate of 28 kHz. A theoretical analysis that describes the passive Q-switching dynamics of GaAs is presented.

  1. Linearly polarized, Q-switched Er-doped fiber laser based on reduced graphene oxide saturable absorber

    CERN Document Server

    Sobon, Grzegorz; Jagiello, Joanna; Kozinski, Rafal; Librant, Krzysztof; Zdrojek, Mariusz; Lipinska, Ludwika; Abramski, Krzysztof M

    2012-01-01

    We demonstrate generation of linearly polarized pulses from a passively Q-switched Erbium-doped fiber laser. The cavity was designed using only polarization maintaining (PM) fibers and components, resulting in linearly polarized output beam with degree of polarization (DOP) at the level of 97.6%. Reduced graphene oxide (rGO) was used as a saturable absorber for Q-switched operation. The laser was capable of delivering 1.85us pulses with 125nJ pulse energy at 115kHz repetition rate.

  2. Hybrid Q-switched broadband laser source with low timing jitter.

    Science.gov (United States)

    El Bassri, Farid; Doutre, Florent; Mothe, Nicolas; Jaffres, Lionel; Pagnoux, Dominique; Couderc, Vincent; Jalocha, Alain

    2012-01-16

    We present a novel broadband laser source based on a dual cavity in which a subnanosecond passively Q-switched microchip laser is coupled with a long cavity including an acousto-optic modulator (AOM) and a microstructured optical fiber working as a non linear medium. This active-passive Q-switched laser source emits pulses as short as those emitted by the free running microchip laser (~600 ps). The time pulse emission is governed by the AOM allowing tunable repetition rate from 0 to more than 4 kHz with a temporal jitter reduced to less than 50 ns, i.e. a 600-fold reduction compared to that of the free running microchip. Furthermore, thanks to spectral broadening in the microstructured fiber, this source emits a supercontinuum from 700 nm to 1700 nm.

  3. Zinc oxide (ZnO) nanoparticles as saturable absorber in passively Q-switched fiber laser

    Science.gov (United States)

    Ahmad, H.; Lee, C. S. J.; Ismail, M. A.; Ali, Z. A.; Reduan, S. A.; Ruslan, N. E.; Ismail, M. F.; Harun, S. W.

    2016-12-01

    We demonstrate a passively Q-switched erbium-doped fiber laser using zinc oxide (ZnO) nanoparticles thin film as saturable absorber (SA). ZnO exhibits high nonlinear optical response and fast recovery time, fulfilling the requirements of an ideal SA. The nonlinear optical absorption is characterised by modulation depth of 3.5% with saturation intensity of 0.016 MW cm-2. We insert the SA into the laser cavity and obtain stable Q-switched pulse whereby the repetition rate increases from 41.7 kHz to 77.2 kHz while the pulse width decreases from 9.6 μs to 3.0 μs as the pump power is increased from 60 mW to 360 mW. This result suggests that ZnO could be a promising SA for photonic applications.

  4. Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

    Institute of Scientific and Technical Information of China (English)

    Xinning Tian(田信宁); Ping Yan(闫平); Qiang Liu(柳强); Mali Gong(巩马理); Yun Liao(廖云)

    2004-01-01

    A pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum(FWHM)is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd:YAG/Cr:YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26%(15)through the pre-pumped modulation technique.

  5. A black phosphorus-based tunable Q-switched ytterbium fiber laser

    Science.gov (United States)

    Ahmad, H.; Salim, M. A. M.; Thambiratnam, K.; Norizan, S. F.; Harun, S. W.

    2016-09-01

    A compact, passively Q-switched fiber laser with a tunable output is demonstrated. The proposed system uses a short length ytterbium doped fiber to create a very stable and compact optical circuit that uses black phosphorus (BP) as a saturable absorber to generate the desired short pulses. A stable Q-switch pulse train is obtained, with an operational wavelength range from 1056.6-1083.3 nm. Concurrently, a maximum pulse energy and minimum pulse width as well as a repetition rate range of 7.1 nJ, 4 µs and 6.0-44.8 kHz respectively was obtained. The proposed system will be able to cater to a multitude of applications that require a compact yet robust and cost-effective pulse laser.

  6. Picosecond pulse generation in a hybrid Q-switched laser source by using a microelectromechanical mirror.

    Science.gov (United States)

    Couderc, Vincent; Crunteanu, Aurelian; Fabert, Marc; Doutre, Florent; El Bassri, Farid; Pagnoux, Dominique; Jalocha, Alain

    2012-02-27

    We present a novel Q-switched laser source using a micro-optical-electromechanical mirror (MOEM) designed for short pulse emission. It is based on a hybrid configuration including a passively Q-switched microchip laser coupled to a fiber cavity closed by a cantilever type MOEM acting as an active modulator. This specially designed mirror with a single reflecting gold membrane is switched by low bias voltage ~50 V (peak to peak). This device emits pulses at tunable repetition rates up to 1.6 kHz, with ~564 ps duration and 3.4 kW peak power, which constitutes the shortest pulse duration ever reported with MOEMs based pulsed lasers.

  7. Diode-pumped continuous wave tunable and graphene Q-switched Tm:LSO lasers.

    Science.gov (United States)

    Feng, T L; Zhao, S Z; Yang, K J; Li, G Q; Li, D C; Zhao, J; Qiao, W C; Hou, J; Yang, Y; He, J L; Zheng, L H; Wang, Q G; Xu, X D; Su, L B; Xu, J

    2013-10-21

    We have investigated the lasing characteristics of Tm:LSO crystal in three operation regimes: continuous wave (CW), wavelength tunable and passive Q-switching based on graphene. In CW regime, a maximum output power of 0.65 W at 2054.9 nm with a slope efficiency of 21% was achieved. With a quartz plate, a broad wavelength tunable range of 145 nm was obtained, corresponding to a FWHM of 100 nm. By using a graphene saturable absorber mirror, the passively Q-switched Tm:LSO laser produced pulses with duration of 7.8 μs at 2030.8 nm under a repetition rate of 7.6 kHz, corresponding to pulse energy of 14.0 μJ.

  8. Black phosphorus-based saturable absorber for Q-switched Tm:YAG ceramic laser

    Science.gov (United States)

    Xie, Yixuan; Kong, Lingchen; Qin, Zhipeng; Xie, Guoqiang; Zhang, Jian

    2016-08-01

    We have experimentally demonstrated a passively Q-switched Tm-doped YAG ceramic laser with black phosphorus (BP) as saturable absorber (SA). According to the measurement, the BP saturable absorber mirror has a modulation depth of 5% and a saturation fluence of 20 μJ/cm2. The generated Q-switched pulse has a maximum average power of 38.5 mW and pulse energy of 3.32 μJ, with the corresponding repetition rate of 11.6 KHz and pulse width of 3.12 μs at 2 μm wavelength. The results show that BP is a promising SA for midinfrared-pulsed lasers.

  9. Q-switched operation of a coupled-resonator vertical-cavity laser diode

    Energy Technology Data Exchange (ETDEWEB)

    FISCHER,ARTHUR J.; CHOW,WENG W.; CHOQUETTE,KENT D.; ALLERMAN,ANDREW A.; GEIB,KENT M.

    2000-02-08

    The authors report Q-switched operation from an electrically-injected monolithic coupled-resonator structure which consists of an active cavity with InGaAs quantum wells optically coupled to a passive cavity. The passive cavity contains a bulk GaAs region which is reverse-biased to provide variable absorption at the lasing wavelength of 990 nm. Cavity coupling is utilized to effect large changes in output intensity with only very small changes in passive cavity absorption. The device is shown to produce pulses as short as 150 ps at repetition rates as high 4 GHz. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulse shape. Small-signal frequency response measurements also show a transition from a slower ({approximately} 300 MHZ) forward-biased modulation regime to a faster ({approximately} 2 GHz) modulation regime under reverse-bias operation.

  10. Passively Q-switching induced by the smallest single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. T.; Zhai, J. P.; Wang, J. S.; Chen, Y. P.; Yu, Y. Q.; Zhang, M.; Li, I. L.; Ruan, S. C., E-mail: scruan@szu.edu.cn [Shenzhen Key Laboratory of Laser Engineering, Shenzhen University, Shenzhen 518060 (China); Tang, Z. K. [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2014-04-28

    We report a passively Q-switched erbium-doped fiber laser (EDFL) by using the smallest single-walled carbon nanotubes (SWNTs) with a diameter of 0.3 nm as the saturable absorber. These small SWNTs are fabricated in the nanochannels of a ZnAPO-11 (AEL) single crystal. By inserting one of the AEL crystal into an EDFL cavity pumped by a 980 nm laser diode, stable passive Q-switching is achieved for a threshold pump power of 206.2 mW, and 4.73 μs pulses with a repetition rate of 41.78 kHz and an average output power of 3.75 mW are obtained for a pump power of 406 mW.

  11. Compressed 6 ps pulse in nonlinear amplification of a Q-switched microchip laser

    Science.gov (United States)

    Diao, Ruxin; Liu, Zuosheng; Niu, Fuzeng; Wang, Aimin; Taira, Takunori; Zhang, Zhigang

    2017-02-01

    We present a passively Q-switched Nd:YVO4 crystal microchip laser with a 6 ps pulse width, which is based on SPM-induced spectral broadening and pulse compression. The passive Q-switching is obtained by a semiconductor saturable absorber mirror. The laser’s seed source centered at 1064 nm pulses with a duration of 80 ps, at a repetition rate of 600 kHz corresponding to an average output power of 10 mW. After amplification and compression, the pulses were compressed to 6 ps with a maximum pulse energy of 0.5 µJ.

  12. Passively Q -Switched 1.57- m Intracavity Optical Parametric Oscillator

    Science.gov (United States)

    Yashkir, Yuri; van Driel, Henry M.

    1999-04-01

    We demonstrate an eye-safe KTP-based optical parametric oscillator (OPO) driven intracavity by a diode-pumped 1064-nm Nd:YAG laser, passively Q -switched by a Cr 4 :YAG crystal. The characteristics of this system, which operates at 1570 nm with a repetition rate as high as 50 Hz, are studied as a function of Cr 4 :YAG optical density. Under optimum conditions the OPO generates 1.5-mJ, 3.4 0.1-ns pulses in a single transverse mode. For a Cr 4 :YAG Q -switch element with an optical density of 0.5 the conversion efficiency of the intracavity energy is 45% with the ratio of OPO to Nd:YAG peak-pulse intensity exceeding unity. These and other OPO characteristics compare favorably with a simple rate equation model of the OPO dynamics.

  13. Passively Q-switched 1.57-microm intracavity optical parametric oscillator.

    Science.gov (United States)

    Yashkir, Y; van Driel, H M

    1999-04-20

    We demonstrate an eye-safe KTP-based optical parametric oscillator (OPO) driven intracavity by a diode-pumped 1064-nm Nd:YAG laser, passively Q-switched by a Cr4+:YAG crystal. The characteristics of this system, which operates at 1570 nm with a repetition rate as high as 50 Hz, are studied as a function of Cr4+:YAG optical density. Under optimum conditions the OPO generates 1.5-mJ, 3.4 +/- 0.1-ns pulses in a single transverse mode. For a Cr4+:YAG Q-switch element with an optical density of 0.5 the conversion efficiency of the intracavity energy is approximately 45% with the ratio of OPO to Nd:YAG peak-pulse intensity exceeding unity. These and other OPO characteristics compare favorably with a simple rate equation model of the OPO dynamics.

  14. Q-Switching the Flash Ti: Sapphire Laser

    Energy Technology Data Exchange (ETDEWEB)

    Cone, Kelly

    2003-09-05

    The Stanford Linear Accelerator Center (SLAC) uses a flash lamp pumped Ti:Sapphire laser to generate the electron beam inside of the Linac. This laser system was installed at the SLAC Polarized Light Source in 1993. During the past, the system has been upgraded in several steps (eg. installation of Rhodium coated reflectors, cavity redesign, and remote controlled wavelength tunability). Q-switching the laser cavity to increase the peak pulse energy was successfully investigated and further improves the capabilities of the laser system for future polarized beam experiments. Two Pockels cells were used to perform the Q-switch and various diagnostics were used to characterize the modified laser pulse. The timing in relation to the laser trigger, pulse width, and pulse shape applied to the Q-switching Pockels cells (PC) were optimized. No damage to the laser cavity or optical elements occurred. At optimal conditions of Q-switching, the pulse energy of the laser increased from 0.4 mJ to over 3 mJ in a 300 ns pulse. The Q-switched pulse energy can be further increased by extending the hold-off pulse applied to the PC. The laser pulse produced by the Q-switch was long enough (full width half maximum (FWHM) > 200 ns) for pulse shaping and demonstrated good intensity stability (< 0.5% jitter). The increase in output power suggests that Q-switching will be used for future accelerator projects.

  15. Diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG/KTP green laser

    Institute of Scientific and Technical Information of China (English)

    Du Shi-Feng; Wang Su-Mei; Zhang Dong-Xiang; Feng Bao-Hua; Zhang Chun-Yu; Zhang Ling; Zhang Zhi-Guo; Zhang Shi-Wen

    2006-01-01

    We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG green laser with a KTP crystal as the intra- cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170 ± 20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.

  16. The generation of Q-switched erbium-doped fiber laser using black phosphorus saturable absorber with 8% modulation depth

    Science.gov (United States)

    Fauziah, C. M.; Rosol, A. H. A.; Latiff, A. A.; Harun, S. W.

    2017-06-01

    We report a generation of the Q-switched laser operating in 1.55-micron region by using black phosphorus (BP) as a saturable absorber (SA). A 980-nm laser diode was pumped into Erbium-doped fiber (EDF) gain medium in ring cavity configuration. The BP-based SA was prepared by mechanically exfoliating the BP crystal using scotch tape. The obtained BP-tape SA has a modulation depth of 8 %. To realize a Q-switching operation, a small piece of the tape is then integrated into between two fiber ferrule tips. A stable Q-switching operation started at 40 mW. The maximum repetition rate obtainable at 28.57 kHz, with pulse width of 5.35 μs. This finding shows the BP is one of the promising material to work as an SA for pulsed laser generation.

  17. Passively Q-switched nanosecond erbium-doped fiber laser with MoS(2) saturable absorber.

    Science.gov (United States)

    Ren, Jun; Wang, Shuxian; Cheng, Zhaochen; Yu, Haohai; Zhang, Huaijin; Chen, Yanxue; Mei, Liangmo; Wang, Pu

    2015-03-09

    Passively Q-switched nanosecond pulsed erbium-doped fiber laser based on MoS(2) saturable absorber (SA) is experimentally demonstrated. The high quality MoS(2) SA deposited on the broadband high-reflectivity mirror with a large modulation depth of 9% was prepared by pulsed laser deposition method. By inserting the MoS(2) SA into an erbium-doped fiber laser, stable Q-switched operation can be achieved with the shortest pulse width of 660 ns, the maximum pulse energy up to 152 nJ and pulse repetition rates varying from 116 to 131 kHz. The experimental results further verify that MoS(2) possesses the potential advantage for stable Q-switched pulse generation at 1.5 μm.

  18. Q-switching of an all-fiber laser by acousto-optic modulation of a fiber Bragg grating

    Science.gov (United States)

    Delgado-Pinar, M.; Zalvidea, D.; Diez, A.; Perez-Millan, P.; Andres, M.

    2006-02-01

    We report active Q-switching of an all-fiber laser using a Bragg grating based acousto-optic modulator. Q-switching is performed by modulating a fiber Bragg grating with an extensional acoustic wave. The acoustic wave modulates periodically the effective index profile of the FBG and changes its reflection features. This allows controlling the Q-factor of the cavity. Using 1 m of 300 ppm erbium-doped fiber and a maximum pump power of 180 mW, Q-switch pulses of 10 W of peak power and 82 ns wide were generated. The pulse repetition rate of the laser can be continuously varied from few Hz up to 62.5 kHz.

  19. Diode-pumped passively Q-switched Nd:GAGG laser at 938 nm with V3+:YAG saturable absorber

    Science.gov (United States)

    Liu, S. D.; Zhang, B. T.; He, J. L.; Yang, H. W.; Xu, J. L.; Liu, F. Q.; Yang, J. F.; Yang, X. Q.; Huang, H. T.

    2010-10-01

    The continuous wave (CW) and passively Q-switched Nd:Gd3AlxGa5-xO12 (Nd:GAGG) laser operation at 938 nm have been realized for the first time. The maximum CW output power of 0.44 W was obtained under the absorbed pump power of 8.54 W, corresponding to the slope efficiency of 7.8% and optical-to-optical efficiency of 5.2% respectively. A V3+:YAG saturable absorber crystal with the initial transmission of 97% was used for the passive Q-switching regime. The maximum average output power of 0.19 W was achieved with the minimum pulse width of 358 ns and Q-switched repetition rate of 116 kHz. The corresponding single pulse energy and pulse peak power were determined to be 1.6 μJ and 4.6 W, respectively.

  20. Q-switched laser tattoo removal

    Directory of Open Access Journals (Sweden)

    Viljem H. topčič

    2013-10-01

    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

  1. An actively Q-switched single-longitudinal-mode fiber laser with an optically pumped saturable absorber

    Science.gov (United States)

    Yun, Hyo-Geun; Lee, Seoung Hun; Lee, Min Hee; Kim, Kyong Hon

    2013-09-01

    We have demonstrated an actively Q-switched single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser by using an EDF saturable absorber modulated under an external laser pulse injection. A laser output of 1531.9 nm wavelength from a distributed-feedback laser diode was amplified with an EDF amplifier and modulated with an external electro-optical modulator, and the modulated signals were used as control pulses to saturate the EDF saturable absorber for the actively Q-switched ring-type fiber laser operation. Actively Q-switched 1542 nm wavelength laser pulses of 4.5 nJ pulse energy and of 4.0μs pulse width were achieved at a repetition rate of 100 Hz. When the Q-switched laser pulse energy was reduced to about 0.54 nJ by decreasing the gain-pump power used for exciting the ring cavity and the control-pulse beam power used for bleaching out the saturable absorber, the SLM laser pulses were achieved. Further improvement of the Q-switched SLM laser pulse output can be achieved simply by using an external laser amplifier and by shortening the cavity length with short pigtailed-fiber laser components, and thus the SLM laser pulses can be useful for various applications.

  2. 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....

  3. A 200 kHz Q-Switched Adhesive-Free Bond Composite Nd:YVO4 Laser using a Double-Crystal RTP Electro-optic Modulator

    Institute of Scientific and Technical Information of China (English)

    YU Yong-Ji; CHEN Xin-Yu; WANG Chao; WU Chun-Ting; LIU Rui; JIN Guang-Yong

    2012-01-01

    A diode-end-pumped electro-optic (EO) Q-switched adhesive-free bond composite Nd:YVO4 laser operating at a repetition rate of 200 kHz is reported. A pair of RbTiOPOi (RTP) crystals are used as a high repetition EO Q-switch. At the repetition rate of 200kHz, the maximum average output power of 11.8 W at wavelength 1064 nm and full width at half maximum of pulses of 16.65 ns are achieved at an incident pump power of 27 W, corresponding to an optical conversion efficiency of 43.7% and a slope efficiency of 44.6%, respectively. To the best of our knowledge, this is the highest repetition rate reported on the EO Q-switched laser by using RTP crystals.%A diode-end-pumped electro-optic (EO) Q-switched adhesive-free bond composite Nd:YVO4 laser operating at a repetition rate of 200 kHz is reported.A pair of RbTiOPO4 (RTP) crystals are used as a high repetition EO Q-switch.At the repetition rate of 200kHz,the maximum average output power of 11.8 W at wavelength 1064 nm and full width at half maximum of pulses of 16.65ns are achieved at an incident pump power of 27 W,corresponding to an optical conversion efficiency of 43.7% and a slope efficiency of 44.6%,respectively.To the best of our knowledge,this is the highest repetition rate reported on the EO Q-switched laser by using RTP crystals.

  4. 4.5 W mid-infrared supercontinuum generation in a ZBLAN fiber pumped by a Q-switched mode-locked Tm3+- doped fiber laser

    Science.gov (United States)

    Kneis, C.; Donelan, B.; Berrou, A.; Manek-Hönninger, I.; Cadier, B.; Robin, T.; Poulain, M.; Joulain, F.; Eichhorn, M.; Kieleck, C.

    2015-02-01

    The generation of mid-infrared (mid-IR) supercontinuum (SC) radiation, ranging from 2 - 5 μm, is subject of intense research due to its wide range of applications. A very popular host media for mid-IR SC generation are soft glass fibers owing to their low-loss transmission in the mid-IR wavelength regime, particularly fluoride fibers are very attractive for high-power operation. In this research study, a diode-pumped Q-switched mode-locked (QML) thulium (Tm3+)-doped double-clad silica fiber laser is used to pump a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber for mid-IR SC generation. The QML regime of the fiber laser is actively generated by two acousto-optic modulators. The Tm3+-fiber laser provided up to 23.5 W (26 W) of average output power in QML (continuous wave) regime with a slope efficiency of 36 % (32 %). The measured beam quality has been close to the diffraction-limit in QML regime. The system delivered mode-locked pulses with a duration of 7.5 ps, measured with a commercial autocorrelator system, at a repetition rate of 46 MHz. The Q-switched envelopes had a width between 50 and 150 ns depending on the output power level and the adjustable repetition rate. Mid-IR SC with an average output power in all spectral bands of 4.5 W have been achieved with more than 3 W/ 1.7 W/ 1 W/ 0.36 W after a long-wave-pass filter with a 3 dB-edge at 2.15 μm/ 2.65 μm/ 3.1 μm/ 3.5 μm.

  5. Passively Q-switched waveguide lasers based on two-dimensional transition metal diselenide.

    Science.gov (United States)

    Cheng, Chen; Liu, Hongliang; Tan, Yang; Vázquez de Aldana, Javier R; Chen, Feng

    2016-05-16

    We reported on the passively Q-switched waveguide lasers based on few-layer transition metal diselenide, including molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2), as saturable absorbers. The MoSe2 and WSe2 membranes were covered on silica wafers by chemical vapor deposition (CVD). A low-loss depressed cladding waveguide was produced by femtosecond laser writing in a Nd:YAG crystal. Under optical pump at 808 nm, the passive Q-switching of the Nd:YAG waveguide lasing at 1064 nm was achieved, reaching maximum average output power of 115 mW (MoSe2) and 45 mW (WSe2), respectively, which are corresponding to single-pulse energy of 36 nJ and 19 nJ. The repetition rate of the Q-switched waveguide lasers was tunable from 0.995 to 3.334 MHz (MoSe2) and 0.781 to 2.938 MHz (WSe2), and the obtained minimum pulse duration was 80ns (MoSe2) and 52 ns (WSe2), respectively.

  6. Efficient graphene Q switching and mode locking of 1.34 μm neodymium lasers.

    Science.gov (United States)

    Xu, Jin-Long; Li, Xian-Lei; He, Jing-Liang; Hao, Xiao-Peng; Yang, Ying; Wu, Yong-Zhong; Liu, Shan-De; Zhang, Bai-Tao

    2012-07-01

    We demonstrate that few-layered graphene sheets used as a saturable absorber can provide efficient Q-switching and mode-locking modulation in 1.34 μm Nd:GdVO(4) bulk lasers. The minimum Q-switched pulses were 450 ns for 260 mW average power, 43 kHz repetition rate, and 2.5 μJ pulse energy. For the mode-locked laser, an average power of 1.29 W was achieved with 11 ps pulse duration and 13 nJ pulse energy. To our knowledge, this average power is the highest yet obtained from a graphene mode-locked laser, and the corresponding optical-optical efficiency of 23% is the best result among 1.3 μm neodymium mode-locked lasers. The quality factor M(2) of the Q-switched beam was 1.4 and 1.6 in the horizontal and longitudinal planes, respectively, and the M(2) of the mode-locked beam reached 1.1 and 1.0. These results clearly indicate the advantages of few-layered graphene as a saturable absorber.

  7. Delivering dispersion-managed soliton and Q-switched pulse in fiber laser based on graphene and nonlinear optical loop mirror

    Science.gov (United States)

    Wang, W. B.; Wang, F.; Yu, Q.; Zhang, X.; Lu, Y. X.; Gu, J.

    2016-11-01

    We propose and experimentally demonstrate a bidirectional erbium-doped fiber laser delivering dispersion-managed soliton (DMS) and Q-switched pulse based on a graphene-polyvinyl alcohol (PVA) and nonlinear optical loop mirror (NOLM) saturable absorbers (SAs). In proposed structure, the DMS is achieved in clockwise (CW) direction and Q-switched pulse is obtained in counter-clockwise (CCW) direction. By properly adjusting the intracavity attenuators (ATT) and polarizer controllers (PCs), DMS in the CW direction and Q-switched pulse in the CCW direction can be obtained, respectively or simultaneously. The DMS with full width at half maximum (FWHM) of ~480 fs, signal to noise ratio (SNR) of ~60 dB and repetition frequency about 3.907 MHz is obtained. The Q-switched pulse is established at a pump power of 180 mW with a repetition rate of ~43.5 kHz and FWHM of ~8.18 μs. When the pump power is increased to 700 mW, Q-switched pulse with a repetition rate of ~107.1 kHz and FWHM of ~2.15 μs is generated. When the two type pulses are formed simultaneously, the maximum repetition rate of Q-switched pulse is 55.8 kHz and minimum FWHM is 2.81 μs, the DMS can be formed by properly adjusting PC and ATT in this case. To the best of our knowledge, it is the first time that Q-switched pulse and DMS have been acquired respectively or simultaneously in a fiber laser.

  8. Two side liquid-cooled and passively Q-switched disk oscillator with nanosheets in flowing CCl4

    Science.gov (United States)

    Nie, Rongzhi; She, Jiangbo; Li, Dongdong; Li, Fuli; Peng, Bo

    2016-09-01

    A passively Q-switched and two side liquid-cooled Nd:YAG disk oscillator is demonstrated, which is operated at a pump pulse width of 300 μs and a pump repetition rate of 10 Hz. The coolant flows over the two large surfaces of the disk and will be passed through by laser beam, so it can also serve as a saturable absorber. For the unmodulated laser, the pure CCl4 was employed as coolant and a plane output mirror of 15 % transmission was employed. The maximum output energy of 795 mJ is realized corresponding to the optical-optical efficiency of 27.4 % and the slope efficiency of 30 %; for the graphene Q-switched laser, the CCl4 with graphene nanosheets was employed as coolant and a plane output mirror of 40 % transmission was employed. The maximum output energy of 376 mJ is realized corresponding to the optical-optical efficiency of 13 % and the slope efficiency of 18 %. The maximum average Q-switching repetition rate is 385 kHz, and the minimum average pulse width is 116 ns; for the MoS2 Q-switched laser, the CCl4 with MoS2 nanosheets was employed as coolant and a plane output mirror of 30 % transmission was employed. The maximum output energy of 486 mJ is realized corresponding to the optical-optical efficiency of 17 % and the slope efficiency of 22 %.The maximum average Q-switching repetition rate is 470 kHz, and the minimum average pulse width is 137 ns.

  9. Diode-end-pumped electro-optically Q-switched Nd:YLF slab laser.

    Science.gov (United States)

    Zhang, Hengli; Du, Keming; Li, Daijun; Shi, Peng; Wang, Yongdong; Diart, Robert

    2004-05-10

    We report a very compact Nd:YLF slab laser that is end pumped by a quasi-continuous-wave diode stack. A hybrid resonator is used to generate high output power in a near-diffraction-limited beam (i.e., a beam propogation M2 factor of less than 1.2). A pulse energy of 14.3 mJ was obtained with a pulse width of 8.5 ns at a repetition rate of 500 Hz, which corresponds to a Q-switched peak power of 1.68 MW.

  10. Efficient Diode-Pumped Passively Q-Switched Nd:GdVO4 Lasers

    Institute of Scientific and Technical Information of China (English)

    刘杰; 贾玉磊; 杨济民; 杜鹃; 何京良

    2002-01-01

    An efficient diode-pumped Nd:GdVO4 laser passively Q-switched by a Cr4+ :YAG has been developed as a saturable absorber. A KTP crystal is used for the extra-cavity second-harmonic generation and a BBO crystal for the sum frequency mixing. The green output power is 172mW at incident pump power of 8 W. The ultraviolet (UV) output power is measured to be 20mW at the same pump power. The peak power of the UV laser is 143 W with the pulse repetition rate of 14 kHz and pulse width of 10 ns.

  11. Graphene-based Q-switched pulsed fiber laser in a linear configuration

    Institute of Scientific and Technical Information of China (English)

    Y. K. Yap; Richard M. De La Rue; C. H. Pua; S. W. Harun; H. Ahmad

    2012-01-01

    A pulsed laser system is realized with graphene employed as a Q-switch.The graphene is exfoliated from its solution using an optical deposition and the optical tweezer effect.A fiber ferrule that already has the graphene deposited on it is inserted into an erbium-ytterbium laser (EYL) system with linear cavity configuration.We successfully demonstrate a pulsed EYL with a pulse duration of approximately 5.9 μs and a repetition rate of 20.0 kHz.

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

    Energy Technology Data Exchange (ETDEWEB)

    Anzueto S, G.; Estudillo A, M. [FIMEE, Campus Salamanca, Universidad de Guanajuato, Domicilio conocido, Comunidad de Palo Blanco, 36885, A.P. 215-A, Salamanca, Guanajuato (Mexico); Martinez R, A.; Torres G, I. [Centro de Investigaciones en Optica, Lomas del Bosque 115, 37150, Leon, Guanajuato (Mexico); Selvas A, R. [Facultad de Ciencias Fisico Matematicas, UANL, Cd. Universitaria, 66450, Nuevo Leon (Mexico)]. e-mail: gilberto.anzueto@gmail. com

    2008-07-01

    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 {approx}2.5 {mu}J was estimated and the repetition rate was measured in the range of 4-16 KHz. (Author)

  13. 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

    1995-11-01

    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.

  14. 20-kHz watt-level green laser with LGS crystal electro-optic Q-switch

    Institute of Scientific and Technical Information of China (English)

    Hao Tang; Xiaolei Zhu; Junqing Meng; Huaguo Zang

    2009-01-01

    A diode-end-pumped electro-optic(EO)Q-switched green laser operating at the repetition rate of 20 kHz is reported.A block of La3Ga5SiO14(LGS)single crystal is used as a Q-switch and the type I phasematching LiB3O5(LBO)is used as the nonlinear crystal in the second harmonic generation.The 2.3-W average power of 532-nm green laser is obtained at the repetition rate of 20 kHz with the pulse width as short as 10 ns.When the output power is about 1.5 W,the measured power fluctuation is less than 1.4% (root-mean-square,RMS)with the beam quality factor of M2 < 2 in both orthogonal directions.

  15. Passively Q-switched diode-pumped Cr4+:YAG/Nd3+:GdVO4 monolithic microchip laser

    CERN Document Server

    Forget, S; Balembois, F; Georges, P; Landru, N; Feve, J P; Lin, J; Weng, Z; Forget, Sebastien; Druon, Frederic; Balembois, Francois; Georges, Patrick; Landru, Nicolas; Feve, Jean Philippe; Lin, Jiali; Weng, Zhiming

    2006-01-01

    the realization of high repetition rate passively Q-switched monolithic microlaser is a challenge since a decade. To achieve this goal, we report here on the first passively Q-switched diode-pumped microchip laser based on the association of a Nd:GdVO4 crystal and a Cr4+:YAG saturable absorber. The monolithic design consists of 1 mm long 1% doped Nd:GdVO4 optically contacted on a 0.4 mm long Cr4+:YAG leading to a plano-plano cavity. A repetition rate as high as 85 kHz is achieved. The average output power is approximately 400 mW for 2.2 W of absorbed pump power and the pulse length is 1.1 ns.

  16. Tunable Q-switched thulium-doped Fiber Laser using multiwall carbon nanotube and Fabry-Perot Etalon filter

    Science.gov (United States)

    Ahmad, H.; Muhamad, A.; Sharbirin, A. S.; Samion, M. Z.; Ismail, M. F.

    2017-01-01

    In this paper, we demonstrate an electro-tunable Thulium-doped Fiber Laser (TDFL) using a voltage-controlled Fabry-Perot Etalon (FPE) filter with passive Q-switching capability, obtained by using a multi-walled carbon-nanotube (MWCNT) thin-film as a saturable absorber (SA). To the best of our knowledge, this is the first demonstration of a wavelength-tunable Q-switched TDFL using an FPE filter. The tunable TDFL has a wavelength-tuning range of 41.95 nm, from 1965.40 nm up to 2007.35 nm. Q-switching operation starts at a pump power of 94.72 mW and destabilizes at a maximum input pump power of 146.39 mW. By varying the pump power, the repetition rate and the pulse width can be tuned with a maximum tuning range of 15.5 kHz and 7.0 μs respectively. The laser also has a maximum pulse energy of 82.6 nJ and a peak power of 27.52 mW. The use of the MWCNT thin-film as an SA generates a stable Q-switching operation, which is verified by its relatively high signal-to-noise ratio at a value of 55.0 dB.

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

    Directory of Open Access Journals (Sweden)

    Sulaiman Wadi Harun

    2015-06-01

    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.

  18. Study of filamentation with a high power high repetition rate ps laser at 1.03 µm.

    Science.gov (United States)

    Houard, A; Jukna, V; Point, G; André, Y-B; Klingebiel, S; Schultze, M; Michel, K; Metzger, T; Mysyrowicz, A

    2016-04-01

    We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.

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

    Directory of Open Access Journals (Sweden)

    Rosa Weigand

    2015-09-01

    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.

  20. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge

    Science.gov (United States)

    Bulaev, V. D.; Lysenko, S. L.

    2015-07-01

    A high-power repetitively pulsed e-beam-controlled discharge CO2 laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers.

  1. Q-switched thulium-doped fibre laser operating at 1900 nm using multi-walled carbon nanotubes saturable absorber

    Directory of Open Access Journals (Sweden)

    Norazlina Saidin

    2014-06-01

    Full Text Available Simple, low-cost and stable passive Q-switched thulium-doped fibre lasers (TDFLs operating at 1892.4 and 1910.8 nm are demonstrated using 802 and 1552 nm pumping schemes, respectively, in conjunction with a multi-walled carbon nanotubes (MWCNTs saturable absorber (SA. The MWCNTs composite is prepared by mixing the MWCNTs homogeneous solution into a dilute polyvinyl alcohol (PVA polymer solution before it is left to dry at room temperature to produce thin film. Then the film is sandwiched between two FC/PC fibre connectors and integrated into the laser cavity for Q-switching pulse generation. The pulse repetition rate of the TDFL configured with 802 nm pump can be tuned from 3.8 to 4.6 kHz, whereas the corresponding pulse width reduces from 22.1 to 18.3 μs as the pump power is increased from 187.3 to 194.2 mW. On the other hand, with 1552 nm pumping, the TDFL generates optical pulse train with a repetition rate ranging from 13.1 to 21.7 kHz with a pulse width of 11.5–7.9 μs when the pump power is tuned from 302.2 to 382.1 mW. A higher performance Q-switched TDFL is expected to be achieved with the optimisation of the MWCNT-SA saturable absorber and laser cavity.

  2. Continuous-wave and Q-switched performance of an Yb:YAG/YAG composite thin disk ceramic laser pumped with 970-nm laser diode

    Institute of Scientific and Technical Information of China (English)

    Hong Cai; Jun Zhou; Hongming Zhao; Yunfeng Qi; Qihong Lou; Jingxing Dong; Yunrong Wei

    2008-01-01

    Using front face-pumped compact active mirror laser (CAMIL) structure, we have demonstrated an Yb:YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave (CW) and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Qswitched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.

  3. Diode-pumped, Cr:YAG passively Q-switched and mode-locked Nd:YVO4/KTP green laser

    Institute of Scientific and Technical Information of China (English)

    Junying Wang(王军营); Quan Zheng(郑权); Qinghua Xue(薛庆华); Huiming Tan(檀慧明)

    2003-01-01

    The phenomena of simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4/Cr:YAG/KTP green laser are reported and discussed in this paper. With 5.3-W pump power, by using a nearlyhemispherical cavity (the cavity length is only 97 mm), the results of modulation depth of 70% and theperiod of 0.6 ns are obtained, the output power and the repetitive frequency of Q-switched pulse are 90mW and 12 kHz, respectively.

  4. 36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

    Science.gov (United States)

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

    2017-01-01

    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.

  5. Diode-Pumped Passive Q-Switched 946-nm Nd:YAG Laser with 2.1-W Average Output Power

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling; LI Chun-Yong; FENG Bao-Hua; WEI Zhi-Yi; LI De-Hua; FU Pan-Ming; ZHANG Zhi-Guo

    2005-01-01

    @@ We demonstrate a diode-pumped passive Q-switched 946nm Nd:YAG laser with a diffusion-bonded composite laser rod and a co-doped Nd, Cr:YAG as saturable absorber. The average output power of 2.1 W is generated at an incident pump power of 14.3 W. The peak power of the Q-switched pulse is 643 W with 80 kHz repetition rate and 40.8ns pulse width. The slope efficiency and optical conversion efficiency are 17.6% and 14.7%, respectively.

  6. Passive Q-switching of Pr:LiYF4 orange laser at 604 nm using topological insulators Bi2Se3 as saturable absorber

    Science.gov (United States)

    Cheng, Yongjie; Peng, Jian; Bin, Xu; Xu, Huiying; Cai, Zhiping; Weng, Jian

    2017-02-01

    Q-switched laser operation of a laser diode pumped Pr:LiYF4 laser is reported at 604 nm using a topological insulator (TI) Bi2Se3 nanosheet material as saturable absorbers (SAs), for the first time to our knowledge. Stable Q-switched laser operation is obtained with shortest pulse width of about 802 ns, a maximum pulse repetition rate of 130 kHz, pulse energy of about 0.2 μJ and a maximum average output power of 26 mW. This work further extends the working wavelength of Bi2Se3 as saturable absorbers to visible domain.

  7. Thermal, spectral properties and Q-switched laser operation of Nd:SrLaAlO4 crystal

    Science.gov (United States)

    Liu, Shande; Dong, Lulu; Zhang, Xiao; Yao, Yongping; Xu, Yan; Ren, Tingqi; Zheng, Lihe; Su, Liangbi; Berkowski, Marek

    2017-02-01

    The thermal and spectral properties of a Nd:SrLaAlO4 (Nd:SLA) crystal were systematically studied, including thermal diffusivity, thermal expansion, specific heat, thermal conductivity, polarized absorption and emission spectra. Both continuous-wave (CW) and passively Q-switched Nd:SLA laser operations were investigated. The maximum CW output power of 3.54 W was obtained at 1.077 μm, corresponding to an optical-to-optical efficiency of 46.4%. In the passively Q-switched regime, the maximum average power, pulse repetition rate, and shortest pulse width were 1.8 W, 113 kHz, and 12.6 ns, respectively. All the results indicate that the Nd:SLA crystal is a highly efficient gain medium for laser applications.

  8. WS2 as a saturable absorber for ultrafast photonic applications of mode-locked and Q-switched lasers

    CERN Document Server

    Wu, Kan; Wang, Jun; Li, Xing; Chen, Jianping

    2014-01-01

    Two-dimensional (2D) nanomaterials, especially the transition metal sulfide semiconductors, have drawn great interests due to their potential applications in viable photonic and optoelectronic devices, such as saturable absorbers (SAs) and optical switches, etc. In this work, tungsten disulfide (WS2) based SA for ultrafast photonic applications was demonstrated. WS2 nanosheets were prepared using liquid-phase exfoliation method and embedded in polyvinyl alcohol (PVA) thin film for the practical usage. Saturable absorption was observed in the WS2-PVA SA at the telecommunication waveband near 1550 nm. By incorporating WS2-PVA SA into a fiber laser cavity, both stable mode locking operation and Q-switching operation were achieved. In the mode locking operation, the laser obtained femtosecond output pulse width and high spectral purity in the radio frequency spectrum. In the Q-switching operation, the laser had tunable repetition rate and output pulse energy of a few tens of nano joule. Our findings suggest that ...

  9. Passively Q-switched erbium-doped fiber laser using evanescent field interaction with gold-nanosphere based saturable absorber.

    Science.gov (United States)

    Fan, Dengfeng; Mou, Chengbo; Bai, Xuekun; Wang, Shaofei; Chen, Na; Zeng, Xianglong

    2014-07-28

    We demonstrate an all-fiber passively Q-switched erbium-doped fiber laser (EDFL) using a gold-nanosphere (GNS) based saturable absorber (SA) with evanescent field interaction. Using the interaction of evanescent field for fabricating SAs, long nonlinear interaction length of evanescent wave and GNSs can be achieved. The GNSs are synthesized from mixing solution of chloroauricacid (HAuCl4) and sodium citrate by the heating effects of the microfiber's evanescent field radiation. The proposed passively Q-switched EDFL could give output pulses at 1562 nm with pulse width of 1.78 μs, a repetition rate of 58.1 kHz, a pulse energy of 133 nJ and a output power of 7.7 mW when pumped by a 980 nm laser diode of 237 mW.

  10. Passively Q-switched erbium-doped fiber laser at C-band region based on WS₂ saturable absorber.

    Science.gov (United States)

    Ahmad, H; Ruslan, N E; Ismail, M A; Reduan, S A; Lee, C S J; Sathiyan, S; Sivabalan, S; Harun, S W

    2016-02-10

    We demonstrate a Q-switched erbium-doped fiber laser using tungsten disulfide (WS₂) as a saturable absorber. The WS₂ is deposited onto fiber ferrules using a drop-casting method. Passive Q-switched pulses operating in the C-band region with a central wavelength of 1560.7 nm are successfully generated by a tunable pulse repetition rate ranging from 27.2 to 84.8 kHz when pump power is increased from 40 to 220 mW. At the same time, the pulse width decreases from a maximum value of 3.84 μs to a minimum value of 1.44 μs. The signal-to-noise ratio gives a stable value of 43.7 dB. The modulation depth and saturation intensity are measured to be 0.99% and 36.2  MW/cm², respectively.

  11. Active Q-switching in an erbium-doped fiber laser using an ultrafast silicon-based variable optical attenuator.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2011-12-19

    Presented herein is the use of an ultrafast Si-based variable optical attenuator (VOA) as a Q-switch for rare earth-doped fiber lasers. The ultrafast VOA is based on a forward-biased p-i-n diode integrated with a ridge waveguide, which was originally designed and optimized for WDM channel power equalization in optical communication systems. By incorporating a Si-based VOA with a transient time of ~410 ns into an erbium-doped fiber-based Fabry-Perot cavity it has been shown that stable Q-switched pulses possessing a temporal width of less than ~86 ns can be readily obtained at a repetition rate of up to ~1 MHz. The laser's peak power of ~38 W is shown to be obtainable at 20 kHz with a slope efficiency of ~21%.

  12. Analysis of a new structure Q-switched erbium-doped fiber laser based on fiber grating loop mirror

    Science.gov (United States)

    Cai, Haiwen; Xia, Jiangzhen; Chen, Gaoting; Fang, Zujie; Kim, Insoo S.; Kim, Yohee

    2001-10-01

    In this paper a new structure all fiber Q-switched Erbium-doped fiber laser by using all-fiber wavelength selective intensity modulator based on fiber grating loop mirror (FGLM) was reported. This Q-switched scheme not only modulates loss of the cavity but also selects wavelength. Stable optical pulse with 3 dB linewidth of 0.07 nm, pulse width of 1.4 microsecond(s) , average power of 14.2 mW, and peak power of 1.267 W at 80 mW pump power and 8 KHz repetition rates was obtained in experiments. The generation of single laser pulses and its stability were discussed.

  13. Passively Q-switched erbium-doped fiber laser using Fe3O4-nanoparticle saturable absorber

    Science.gov (United States)

    Bai, Xuekun; Mou, Chengbo; Xu, Luxi; Wang, Shaofei; Pu, Shengli; Zeng, Xianglong

    2016-04-01

    We experimentally demonstrate passively Q-switched erbium-doped fiber laser (EDFL) operation using a saturable absorber (SA) based on Fe3O4 nanoparticles (FONPs). As a type of transition metal oxide, the FONPs have a large nonlinear optical response and fast response time. The FONP-based SA possesses a modulation depth of 8.2% and nonsaturable absorption of 56.6%. Stable passively Q-switched EDFL pulses with an output pulse energy of 23.76 nJ, a repetition rate of 33.3 kHz, and a pulse width of 3.2 µs were achieved when the input pump power was 110 mW. The laser features a low threshold pump power of ∼15 mW.

  14. 888 nm pumped dual Nd:YVO4 crystals acousto-optic Q-switched laser

    Science.gov (United States)

    Zhang, Wenqi; Shen, Yijie; Meng, Yuan; Gong, Mali

    2017-10-01

    888 nm pumped acousto-optic (AO) Q-switched laser with high output power and high efficiency under dual Nd:YVO4 crystals configuration is firstly demonstrated and rate equations for dual-crystal lasers are further ameliorated and investigated. In continuous wave (CW) operation, we experimentally achieve a maximum output power exceeding 50 W. The global optical efficiency reaches 49.5% and the slope efficiency attains 55.5% via using a 1.5 at.% crystal with a 0.5 at.% crystal. In Q-switch operation, by utilizing double 0.5 at.% crystals, the global optical efficiency rises from 25.6% to 45.6% and the pulse duration varies from 26.2 to 42.4 ns when pulse repetition frequency (PRF) increases from 10 to 100 kHz. The measured beam quality factors M2 at 100 kHz are 1.012 and 1.041 with 52.8 W output power in the two orthogonal directions respectively.

  15. Molybdenum disulfide side-polished fiber saturable absorber Q-switched fiber laser

    Science.gov (United States)

    Ahmad, H.; Hassan, H.; Safaei, R.; Thambiratnam, K.; Ismail, M. F.; Amiri, I. S.

    2017-10-01

    A Q-switched fiber laser based on a Molybdenum disulfide (MoS2) saturable absorber (SA) is proposed and demonstrated. A 3 m long erbium-doped fiber with an absorption coefficient of 11.3 dB/m at 979 nm acts as the linear gain medium of the laser. The SA is formed by depositing a MoS2 layer on a self-fabricated side-polished fiber (SPF), which can be easily fabricated in less than 15 min. The proposed laser has a Q-switching threshold of 14.8 mW, and is capable of generating a pulsed output with a repetition rate and pulse-width of up to 25.27 kHz and 3.19 μs at a maximum pump power of 45.6 mW, as well as an average output power and pulse energy of 2.27 mW and 0.09 μJ at the same pump power. The pulses have an average signal-to-noise ratio of 37.8 dB, indicating a stable output and making the proposed laser highly suited for a variety of sensor, communications, and industrial applications.

  16. Passively Q-switched EDFL using Fe3O4-nanoparticle saturable absorber

    CERN Document Server

    Bai, Xuekun; Xu, Luxi; Huang, Sujuan; Wang, Tingyun; Pu, Shengli; Zeng, Xianglong

    2015-01-01

    We experimentally demonstrate a passively Q-switched erbium-doped fiber laser (EDFL) operation by using a saturable absorber based on Fe3O4 nanoparticles (FONP) in magnetic fluid (MF). As a kind of transition metal oxide, the FONP has a large nonlinear optical response with a fast response time for saturable absorber. By depositing MF at the end of optical fiber ferrule, we fabricated a FONP-based saturable absorber, which enables a strong light-matter interaction owing to the confined transmitted optical field within the single mode fiber. Because of large third-order optical nonlinearities of FONP-based saturable absorber, large modulation depth of 8.2% and non saturable absorption of 56.6% are demonstrated. As a result, stable passively Q-switched EDFL pulses with maximum output pulse energy of 23.76 nJ, repetition rate of 33.3 kHz, and pulse width of 3.2 {\\mu}s are achieved when the input pump power is 110 mW at the wavelength of 980 nm. The laser features a low threshold pump power of ~15 mW.

  17. S-band Q-switched fiber laser using MoSe2 saturable absorber

    Science.gov (United States)

    Ahmad, H.; Ismail, M. A.; Sathiyan, S.; Reduan, S. A.; Ruslan, N. E.; Lee, C. S. J.; Zulkifli, M. Z.; Thambiratnam, K.; Ismail, M. F.; Harun, S. W.

    2017-01-01

    A passively Q-switched S-band fiber laser using Molybdenum Diselenide (MoSe2) saturable absorber (SA) is proposed and demonstrated. The SA is fabricated by depositing MoSe2 onto two fiber ferrules using the drop-cast method before heating and connecting the two fiber ferrules to form the SA. The passively Q-switched fiber laser designed using the MoSe2 SA has an operational range of 1491.0-1502.0 nm. The output pulse train has a pulse-width ranging from 2.0 μs to 1.0 μs and corresponding repetition rate of between 34.5 kHz and 90 kHz with increasing pump powers, as well as a signal-to-noise of about 35.97 dB. The peak performance of the proposed laser is between 1480.0 and 1490.0 nm, corresponding to the first peak gain region with the S-band.

  18. High-efficiency Q-switched erbium fiber laser using a Bragg grating-based modulator

    Science.gov (United States)

    Russo, N. A.; Duchowicz, R.; Mora, J.; Cruz, J. L.; Andrés, M. V.

    2002-09-01

    In this work we analyze the behavior of an erbium-doped fiber laser which is based on a simple scheme. Excitation of the active medium is performed in the 980 nm pump band with a CW semiconductor laser source. Two fiber Bragg gratings acting as mirrors of the Fabry-Perot laser cavity were used. One of these gratings was mounted over a piezoelectric (PZT) element. By applying voltage pulses to the piezoelectric, the laser cavity was temporally modulated and Q-switched laser pulses up to 530 mW peak powers at 3 kHz were obtained. Typical laser emission of 2-3 μs temporal widths and 0.1 nm of optical bandwidth have been achieved when the system was operated at 18.5 kHz repetition rates. Different behaviors were observed depending on the pumping level of the active medium and on the amplitude and frequency of the signal applied on the PZT. Q-switched laser output, in the erbium spectral gain region, with high laser efficiency of energy conversion was generated. Pumping at 76 mW and operating the laser at 18.5 kHz, an efficiency of 26% was obtained.

  19. Tungsten diselenide Q-switched erbium-doped fiber laser

    Science.gov (United States)

    Chen, Bohua; Zhang, Xiaoyan; Guo, Chaoshi; Wu, Kan; Chen, Jianping; Wang, Jun

    2016-08-01

    We report a tungsten diselenide (WSe2) polyvinyl alcohol (PVA)-based, saturable absorber and related experiment results of a Q-switched fiber laser. WSe2-PVA film is synthesized by liquid phase exfoliation method, and its saturable absorption is measured via a nonlinear transmission experiment. The result shows that WSe2-PVA saturable absorber has a modulation depth of 3.5%, which means it has potential for generating an ultrafast pulse laser. We apply this absorber into a ring-cavity erbium-doped fiber laser and obtain Q-switched pulses under appropriate pump power. Our work demonstrates the reliable nonlinear optical characteristics of WSe2 and the feasibility for this two-dimensional material to be applied in the field of nonlinear optics.

  20. High Speed Crystal Growth by Q-switched Laser Melting

    Science.gov (United States)

    Cullis, A. G.

    1984-01-01

    The modification of the structural and electrical properties of semiconductors short radiation pulses obtained from Q-switched lasers is described. These modifications are accomplished by high heating and cooling rates. This processing revealed novel crystal growth and high speed resolidification phenomena. The behavior of semiconductor Si is analyzed. The annealing process typically employs short pulses of radiation in or near the visible region of the spectrum. The Q-switched ruby and Nd-YAG lasers are commonly used and these are sometimes mode locked to reduce the pulse length still further. Material to be annealed can be processed with a single large area radiation spot. Alternatively, a small radiation spot size can be used and a large sample area is covered by overlapping irradiated regions.

  1. High-power, high-repetition-rate performance characteristics of β-BaB₂O₄ for single-pass picosecond ultraviolet generation at 266 nm.

    Science.gov (United States)

    Kumar, S Chaitanya; Casals, J Canals; Wei, Junxiong; Ebrahim-Zadeh, M

    2015-10-19

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz.

  2. Tunable GHz pulse repetition rate operation in high-power TEM(00)-mode Nd:YLF lasers at 1047 nm and 1053 nm with self mode locking.

    Science.gov (United States)

    Huang, Y J; Tzeng, Y S; Tang, C Y; Huang, Y P; Chen, Y F

    2012-07-30

    We report on a high-power diode-pumped self-mode-locked Nd:YLF laser with the pulse repetition rate up to several GHz. A novel tactic is developed to efficiently select the output polarization state for achieving the stable TEM(00)-mode self-mode-locked operations at 1053 nm and 1047 nm, respectively. At an incident pump power of 6.93 W and a pulse repetition rate of 2.717 GHz, output powers as high as 2.15 W and 1.35 W are generated for the σ- and π-polarization, respectively. We experimentally find that decreasing the separation between the gain medium and the input mirror not only brings in the pulse shortening thanks to the enhanced effect of the spatial hole burning, but also effectively introduces the effect of the spectral filtering to lead the Nd:YLF laser to be in a second harmonic mode-locked status. Consequently, pulse durations as short as 8 ps and 8.5 ps are obtained at 1053 nm and 1047 nm with a pulse repetition rate of 5.434 GHz.

  3. Efficient Laser-Diode End-Pumped Passively Q-Switched Mode-Locked Yb:LYSO Laser Based on SESAM

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang; LI Wen-Xue; HAO Qiang; ZHAI Hui; ZENG He-Ping

    2008-01-01

    We report an eddicient Q-switched laser action based on a semiconductor saturable absorber mirrors(SESAMs)as passively Q-switched laser starter and a Yb:LYSO alloyed crystal as gain material pumped directly by 974nm In GaAs laser diodes.The output pulse duration is measured to be about 7μs,while the average power and the repetition rate of the pulse chain are about 0.92 W and 6.2kHz.respectively,under 12.5 W absorbed pumping power.The Q-switched mode-locked pulse train is also observed in this setup.The laser performance shows that Yb:LYSO is a promising laser gain medium for laser-diode pumped compact solid-state lasers.

  4. Diode-pumped passively Q-switched and mode-locked Nd:YLF laser with Cr4+:YAG saturable absorber

    Institute of Scientific and Technical Information of China (English)

    Shudi Pan; Kezhen Han; Hongmei Wang; Xiuwei Fan; Jingliang He

    2006-01-01

    @@ A diode-pumped passively Q-switched Nd:YLF laser was demonstrated by using saturable absorber of Cr4+:YAG. At the incident power of 7.74 W, pure passively Q-switched laser with per pulse energy of 210 Μj and pulse width of 19.6 ns at repetition rate of 1.78 kHz was obtained by using Cr4+:YAG with initial transmission of 80%. At the incident power of 8.70 W, a Q-switched mode-locking with average output power of 650 Mw was achieved, the overall slop efficiency was 16%, corresponding to the initial transmission of 85% of Cr4+ :YAG.

  5. Comparative study of passively Q-switched c-cut Nd:YVO4/Nd:YAG lasers based on CVD graphene and controlled operation

    Science.gov (United States)

    Jia, Fuqiang; Liu, Pei; Li, Kang; Chen, Hao; Cheng, Yongjie; Cai, Zhiping; Copner, Nigel

    2017-07-01

    In this paper, a comparative study of passively Q-switched c-cut Nd:YVO4 and Nd:YAG lasers using four different layers CVD graphene as saturable absorber are demonstrated experimentally for the first time. Moreover, it is successful to accurately control the frequency of repetition rates of the CVD graphern passively Q-switched lasers by pulsed pump. The impacts of laser materials, layers of CVD graphene and cavity length on output parameters are investigated intensively as well, the result shows that the c-cut Nd:YVO4 is a promising laser media compared with Nd:YAG for passively Q-switched lasers based on CVD graphene, as it has better performances in pulse width, pulse energy and peak power. A useful and cost-effective way to generate stable pulsed lasers by CVD graphene or other novel saturable materials are demonstrated.

  6. Fabrication of narrow pulse passively Q-switched self-stimulated Raman laser with c-cut Nd:GdVO4

    Science.gov (United States)

    Shen, Gao; Li, Zuo-han; Han, Ming

    2016-11-01

    Combining the self-stimulated Raman scattering technology and saturable absorber of Cr4+:YAG, a 1.17 μm c-cut Nd:GdVO4 picosecond Q-switched laser is demonstrated in this paper. With an incident pump power of 10 W, the Q-switched laser with average power of 430 mW for 1.17 μm, pulse width of 270 ps, repetition rate of 13 kHz and the first order Stokes conversion efficiency of 4.3% is obtained. The Q-switched pulse width can be the narrowest in our research. In addition, the yellow laser at 0.58 μm is also achieved by using the LiB3O5 frequency doubling crystal.

  7. Q-switched 2 μm thulium bismuth co-doped fiber laser with multi-walled carbon nanotubes saturable absorber

    Science.gov (United States)

    Saidin, N.; Zen, D. I. M.; Ahmad, F.; Haris, H.; Ahmad, H.; Dimyati, K.; Harun, S. W.; Halder, A.; Paul, M. C.; Pal, M.; Bhadra, S. K.

    2016-09-01

    We report a passively Q-switched fiber laser operating at 1900 nm region using the newly developed thulium bismuth co-doped lithium-alumino-germano-silicate fiber (TBF) as a gain medium in conjunction with a multiwall carbon nanotubes (MWCNTs) based saturable absorber (SA). The TBF and MWCNTs are fabricated and prepared in-house. By increasing the 802 nm pump power from 106.6 to 160 mW, stable generation of Q-switched TBFL has been obtained at 1857.8 nm wavelength. The pulse repetition rate varies from 12.84 to 29.48 kHz while pulse width is increased from 9.6 to 6.1 μs. The performance of the laser is also compared with the Q-switched TDFL, which was obtained using a similar MWCNTs SA and pump wavelength. The Q-switched TDFL generates an optical pulse train with a repetition rate increasing from 3.8 to 4.6 kHz and pulse width reducing from 22.1 to 18.3 μs when the pump power is tuned from 187.3 to 194.2 mW. This shows that the TBFL performs better than the TDFL in terms of threshold pump power, repetition rate and pulse width.

  8. Stability of a Laser-diode-pumped Cr4+∶YAG Passively Q-switched Nd3+∶YAG Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xingyu; ZHAO Shengzhi; WANG Qingpu; ZHANG Qidi; B. Ozygus; M. Weber

    2000-01-01

    In this paper, the stability of a laser-diode-pumped Cr4+∶YAG passively Nd3+∶YAG Q-switched laser and the influence of the transversal mode structure on the stability are investigated. With the laser operating in TEM00 mode, the pulse energy fluctuation and the repetition rate fluctuation as functions of the repetition rate are measured, and semi-quantitatively and qualitatively analyzed, respectively.

  9. Diode-pumped Q-switched Nd:YLF laser at 1313 nm

    Science.gov (United States)

    Xu, Shan; Gao, Shufang; Zheng, Chunyan

    2016-06-01

    In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical-optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.

  10. Laser Cleaning Using Q-Switched Nd:YAG Laser of Low Carbon Steel Alloys

    Directory of Open Access Journals (Sweden)

    S. N. Ali

    2014-01-01

    Full Text Available This paper represents the efforts to achieve the laser cleaning process of low carbon steel alloys AISI1005 and AISI1012 with 0.65 mm and 1 mm thickness, respectively. The cleaning experiments were performed with a Q-switched Nd:YAG nanosecond laser at wavelengths of 1064 nm and 532 nm. The parameters that have been selected for the present work are peak power which varies as 5, 15, 30, 40, and 50 MW and pulse repetition rate which varies from 1 to 6 Hz by 1 Hz increment. Effects of these parameters on the microstructure and the mechanical properties of the two alloys have been realized. Also predicted results of analytical model regarding the depth were compared with the experimental results which show a good agreement between both.

  11. Passively Q-switched and mode-locked erbium doped fiber laser based on N-doped graphene saturable absorber

    Science.gov (United States)

    Ahmad, H.; Aidit, S. N.; Ooi, S. I.; Rezayi, M.; Tiu, Z. C.

    2017-10-01

    A passively Q-switched and mode-locked erbium-doped fiber laser based on a nitrogen-doped graphene saturable absorber is demonstrated. The N-doped graphene based saturable absorber has a modulation depth of 37.88% and a saturation intensity of 0.016 73 MW cm‑2. By integrating the N-doped graphene saturable absorber into the laser cavity, a stable Q-switched operation with a centre wavelength of 1561.1 nm is obtained with a pulse energy of up to 29.0 nJ. As the pump power increases, the Q-switching operation transits into a mode-locking operation. The mode-locking operation is achieved with a centre wavelength of 1560 nm, a pulse width of 0.98 ps, a repetition rate of 28.5 MHz and a signal to noise ratio of up to 40 dB in the RF spectrum.

  12. Tunable Q-switched erbium-doped fiber laser based on curved multimode fiber and graphene oxide saturable absorber

    Science.gov (United States)

    Ahmad, H.; Zulkifli, A. Z.; Thambiratnam, K.

    2017-05-01

    A tunable Q-switched erbium-doped fiber laser using a singlemode-multimode-singlemode fiber structure as a wavelength tuning filter and a graphene oxide saturable absorber is proposed and demonstrated. The system allows the Q-switched laser to be tuned between the wavelengths of 1550.78 nm and 1560.62 nm, giving a tuning range of 9.84 nm. At a Q-switched laser wavelength of 1552.75 nm, a repetition rate of 39.1 kHz and pulse width of 3.6 µs, as well as an average output power of 1.32 mW and pulse energy of 33.8 nJ at a maximum pump power of 79 mW are obtained. Radio frequency analysis shows an average signal-to-noise ratio of 38.8 dB across the measured operating wavelengths, confirming that the system is stable and reliable, with small pulse width and intensity fluctuations.

  13. 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

    2016-11-01

    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.

  14. Multilayer graphene for Q-switched mode-locking operation in an erbium-doped fiber laser

    Science.gov (United States)

    Wang, Zhiteng; Zhu, Shou-En; Chen, Yu; Wu, Man; Zhao, Chujun; Zhang, Han; Janssen, G. C. A. M.; Wen, Shuangchun

    2013-07-01

    We report the laser operation of Q-switched mode-locking (QML) in an erbium-doped fiber laser by using a multilayer graphene saturable absorber (SA), which consists of 22-layer of graphene fabricated by the chemical vapor deposition method. Based on our balanced twin detector measurement, the graphene sample is confirmed to show a saturable intensity of 3.375 MW/cm2 and an absolute modulation depth of 40.27%. It is demonstrated that this graphene SA can readily produce high quality QML pulses. At the pump power of 391.9 mW, the stable mode-locked pulse train with the Q-switched envelope repetition rate of 16.98 kHz and the envelope width of 13.84 μs are achieved. The maximal main pulse peak power can reach up to 35.89 W. This verifies that the multilayer graphene can be still applied as an effective saturable absorber for passively Q-switched mode-locked operation.

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

    Science.gov (United States)

    Feng, Tianxian; Mao, Dong; Cui, Xiaoqi; Li, Mingkun; Song, Kun; Jiang, Biqiang; Lu, Hua; Quan, Wangmin

    2016-11-11

    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.

  16. Q-switched fibre laser using 21 cm Bismuth-erbium doped fibre and graphene oxide as saturable absorber

    Science.gov (United States)

    Ahmad, Harith; Zulkifli, Ahmad Zarif; Kiat, Yap Yuen; Harun, Sulaiman Wadi

    2014-01-01

    A compact, Q-switched fibre laser is proposed and demonstrated using a compact Bismuth-based erbium doped fibre (Bi-EDF) together with a Graphene Oxide (GO) Saturable Absorber (SA). The 21 cm long Bi-EDF has an erbium dopant concentration of 6300 ppm with absorption rates of about 83 and 133 dB/m at 1480 and 1530 nm. The SA is fabricated from graphene flakes dissolved in water, forming a GO film that is sandwiched between two FC/PC connectors. The Q-switched Bi-EDF laser has an Amplified Spontaneous Emission (ASE) spectrum of 120 nm, stretching from 1490 to 1610 nm and a Q-switching threshold power of about 65 mW. At the maximum pump power of 118 mW, the pulses are generated with an average output power and pulse energy of 0.11 mW and 4.3 nJ, with a repetition rate and pulse width of 27.2 kHz and 7.7 μs. The output can be tuned over the amplified spontaneous emission spectrum with an average peak power of about -16.8 dBm, and observation under a radio frequency spectrum analyser shows a highly stable output at 21.8 kHz. The proposed Bi-EDF laser will have substantial uses in applications requiring short and stable pulses such as rangefinding and sensing.

  17. Microstructure and mechanical changes induced by Q-Switched pulse laser on human enamel with aim of caries prevention

    Science.gov (United States)

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

    2016-03-01

    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.

  18. 456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction.

    Science.gov (United States)

    Choudhary, Amol; Beecher, Stephen J; Dhingra, Shonali; D'Urso, Brian; Parsonage, Tina L; Grant-Jacob, James A; Hua, Ping; Mackenzie, Jacob I; Eason, Robert W; Shepherd, David P

    2015-05-01

    In this Letter, we present a passively Q-switched Yb:Y2O3 waveguide laser using evanescent-field interaction with an atmospheric-pressure-chemical-vapor-deposited graphene saturable absorber. The waveguide, pumped by a broad area diode laser, produced an average output power of 456 mW at an absorbed power of 4.1 W. The corresponding pulse energy and peak power were 330 nJ and 2 W, respectively. No graphene damage was observed, demonstrating the suitability of top-deposited graphene for high-power operation.

  19. Passively Q-switched single-frequency 2μm laser used graphene as saturable absorber

    Science.gov (United States)

    Wang, Lei

    2016-04-01

    A graphene passively Q-switched single frequency Ho:YAG laser was demonstrated. Ho:YAG crystal was resonantly pumped by a 1908 nm diode laser. Twisted-mode single frequency technique was applied to realize single frequency oscillation. The maximum single frequency laser output was 358 mW. Single frequency pulse laser output was achieved by inserting a graphene into the single frequency Ho:YAG laser. The maximum average power of 149 mW was obtained with the pulse repetition rate of 40.45 kHz under 8.32 W of incident pump power.

  20. >220W output power at 355nm from a Q-switched diode-pumped solid-state laser

    Science.gov (United States)

    Hay, Nick; Slavinskis, Nerijus; Rodin, Aleksej M.; Kwon, Young Key

    2014-02-01

    We demonstrate 220 W average power at 355 nm from a diode-pumped acousto-optically Q-switched Nd:YAG laser using intracavity second harmonic generation and sum frequency mixing in a nested sub-cavity design. The laser generates linearly polarised pulses with duration 65 ns at repetition rate 10 kHz. Polarisation multiplexing is used to combine two orthogonal beams giving total output pulse energy 22 mJ with peak power cost of ownership DPSS lasers for high-throughput industrial processes in the UV.

  1. Stable single-mode operation of injection-seeded Q-switched Nd:YAG laser by sine voltage modulation

    Institute of Scientific and Technical Information of China (English)

    Yongfei Gao; Junxuan Zhang; Huaguo Zang; Xiaolei Zhu; Yingjie Yu; Weibiao Chen

    2016-01-01

    Based on the modified ramp and fire technique,a novel injection seeding approach with real-time resonance tracking is successfully demonstrated in a single-frequency Nd:YAG pulsed laser.Appling a high-frequency sinusoidal modulation voltage to one piezo actuator and an adjustable DC voltage to another piezo actuator for active feedback,single-mode laser output with high-frequency stability is obtained,and the effect of the piezo hysteresis on the frequency stability can be eliminated for a laser diode pumped Q-switched Nd:YAG laser at a repetition rate of 400 Hz.

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

    Science.gov (United States)

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

    2016-04-04

    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.

  3. 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: z2chen@uci.edu, E-mail: ckim@pusan.ac.kr [Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, California 92612 (United States); Kim, Chang-Seok, E-mail: z2chen@uci.edu, E-mail: ckim@pusan.ac.kr [Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2016-04-04

    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.

  4. Smart Q-switching for single-pulse generation in an erbium-doped fiber laser.

    Science.gov (United States)

    Escalante-Zarate, Luis; Barmenkov, Yuri O; Kolpakov, Stanislav A; Cruz, José L; Andrés, Miguel V

    2012-02-13

    In this paper, we report an active Q-switching of an erbium-doped fiber laser with special modulation functions and novel laser geometry. We experimentally demonstrate that using such a smart Q-switch approach, Q-switch ripple-free pulses with Gaussian-like shape and 17.3 ns width can be easily obtained. The idea behind the smart Q-switch is to suppress one of two laser waves contra-propagating along the fiber cavity, which arises after Q-cell opening, and to eliminate the minor sub-pulses.

  5. Repetitive characteristics of solid state high power long pulse generator%固态化高功率长脉冲驱动源重频特性

    Institute of Scientific and Technical Information of China (English)

    高景明; 杨汉武; 李嵩; 晏龙波; 钱宝良; 张军

    2016-01-01

    A solid state high power long pulse generator has been designed and constructed based on the key technologies of magnetic switch,low impedance pulse forming line,and inductive voltage adder,which was verified by single mode operation for peak power of 2 GW.For repetitive operation,a repetitive primary power supply of moderate voltage level was developed,the two stage magnetic pulse compressor was improved from aspects of reset and insulation,the pulsed charging was optimized where the inductive voltage adder was utilized for pulsed voltage step-up as well as for pulse charging and on-line direct current (DC)re-set was achieved by reasonable design of reset current path.At present,the experimental results achieved on a dummy load are output pulsed power of 2.1 GW,pulse width of 1 70 ns,repetitive rate of 20 Hz,operation time of 1 s and good for repeatability. For further improvement,the pseudospark switch would be replaced by serial connected thyristors to accomplish all solid-state de-sign.%基于固态化磁开关、低阻抗脉冲形成网络和感应电压叠加等关键技术,提出并研制了一台固态化高功率长脉冲驱动源。在前期通过2 GW 单次实验验证技术方案的基础上,研制了中等电压等级的重复频率初级电源;改进了两级磁脉冲压缩系统的复位和绝缘特性;优化了系统整体电路结构,利用感应电压叠加器完成充电磁开关和脉冲升压的双重功能;设计了合理的复位路径,实现了各部分磁芯的在线直流复位;并开展了重频运行研究。在电阻负载上获得了输出功率2.1 GW、脉宽约170 ns、重复频率20 Hz 及运行时间1 s 的实验结果,脉冲波形的重叠一致性好。

  6. Continuous-wave and Q-switched operation of a compact, diode-pumped Yb3+:KY(WO4)2 planar waveguide laser.

    Science.gov (United States)

    Bain, F M; Lagatsky, A A; Kurilchick, S V; Kisel, V E; Guretsky, S A; Luginets, A M; Kalanda, N A; Kolesova, I M; Kuleshov, N V; Sibbett, W; Brown, C T A

    2009-02-02

    A diode-pumped LPE-grown Yb:KYW planar waveguide laser is demonstrated in a microchip monolithic cavity configuration. Output powers as high as 148 mW and thresholds as low as 40 mW were demonstrated during continuous-wave operation. Pulses of 170 ns duration with maximum pulse energy of 44 nJ at a 722 kHz repetition rate were generated when Q-switched using a semiconductor saturable absorber mirror.

  7. Passively Q-switched erbium-doped fiber laser based on Zn nanoparticles as a saturable absorber

    Science.gov (United States)

    Zaca-Morán, P.; Ortega-Mendoza, J. G.; Lozano-Perera, G. J.; Gómez-Pavón, L. C.; Pérez-Sánchez, G. F.; Padilla-Martínez, J. P.; Felipe, C.

    2017-10-01

    In this work, a passively Q-switched erbium-doped ring laser using zinc nanoparticles as a saturable absorber is studied and experimentally demonstrated. To achieve this, a saturable absorber was developed through a selective incorporation of zinc nanoparticles onto the core of an optical fiber using a coherent light source of an infrared laser at 1550 nm, then the saturable absorber was inserted into a laser cavity. The laser has a threshold pump power of 57.7 mW at 980 nm, and a range of pulse-repetition rate from 12.3 to 43 kHz. The highest pulse energy of 2.6 nJ was obtained at a repetition rate of 43 kHz and an output wavelength of 1565.5 nm. In addition, the saturable absorber was morphologically characterized by using both scanning electron and atomic force microscopy showing a uniform distribution of nanoparticles deposited on the optical fiber core. This is, to the best of our knowledge, the first demonstration of a Q-switched fiber laser using Zn nanoparticles as a device of saturable absorption.

  8. Self Q-switched characteristic based on single longitudinal DBR erbium-doped fiber laser with narrow linewidth pulse output

    Science.gov (United States)

    Lyu, Chengang; Zhang, Shuai; Zhang, Xugeng; Gao, Jiale; Jie, Jin

    2017-09-01

    The self Q-switched characteristic of the single longitudinal-mode distributed Bragg reflector (DBR) erbium-doped fiber laser (EDFL) with narrow linewidth pulse output is demonstrated without any extra saturable absorber or electro-optic and acoustic-optic modulator, and it is provided with a simpler structure and lower cost. The proposed pulse laser operates at approximately 1550.33 nm with a 20 dB bandwidth of 0.56 nm and signal-to-noise ratio of about 55 dB. By increasing the 980 nm pump power from 80-330 mW, the repetition rate of the output pulse increases from 73.53-147.1 kHz while the pulse width decreases from 1.4-0.2 µs, which shows the feature of the narrow linewidth ideally. The maximum pulse energy of 0.379 nJ and peak power of 1897.2 µW are generated with a repetition rate and pulse width of 147.1 kHz and 0.2 µs, respectively. The result shows that the self Q-switched pulse of the DBR EDFL is obviously dependent on the applied pump power and possesses the characteristic of the single longitudinal mode and the narrow linewidth, offering potential utilization in industrial processing and scientific research.

  9. All-fiber multi-wavelength passive Q-switched Er/Yb fiber laser based on a Tm-doped fiber saturable absorber

    Science.gov (United States)

    Posada-Ramírez, B.; Durán-Sánchez, M.; Álvarez-Tamayo, R. I.; Alaniz-Baylón, J.; Ibarra-Escamilla, B.; López-Estopier, R.; Kuzin, E. A.

    2017-03-01

    We report on a ring cavity, multi-wavelength, passive Q-switched erbium–ytterbium double cladding fiber laser based on the use of an unpumped segment of Tm-doped fiber acting as a saturable absorber for passive Q-switched pulse generation and a wavelength filter for multi-wavelength laser generation. By performing pump power variations from 1.6 to 9.8 W, stable Q-switched laser pulses are observed in a repetition rate from 135.8 to 27.5 kHz at room temperature. With a maximal repetition rate of 135.8 kHz, the minimum pulse duration of 430 ns is obtained. The maximal average output power of 2.2 W is reached with a pump power of 9.8 W. The maximum pulse energy was 16.4 µJ and the average output power slope efficiency is ~24.8%. The obtained results demonstrate a laser performance with extended range of high repetition rate and improved stability.

  10. Analysis of New Q-switched Erbium Doped Fiber Laser Based on Fiber Grating Loop Mirror

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An all-fiber wavelength selective Q-switching modulator based on fiber grating loop mirror is proposed. A newly configured Q-switched erbium doped fiber laser using this all-fiber modulator is numerically analyzed taking into account the effects of the spontaneous emission.

  11. Observation of Antiphase State in a Self-Q-switched Nd,Cr:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    SHI Yu-Xian; LI Qi-Nan; DU Shi-Feng; ZHANG Dong-Xiang; ZHANG Zhi-Guo; FENG Bao-Hua; ZHANG Shi-Wen

    2009-01-01

    We experimentally investigate the antiphase dynamics phenomenon in a self-Q-switched Nd, Cr: YA G laser oper-ating at 946 nm. Due to the effect of spatial hole burning, the Q-switched pulses sequences of one, two and three modes at different pump power are observed. The experimental results show that the pulse sequences display classic antiphase dynamics.

  12. 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.

  13. Passively Q-switched Self-frequency Doubling NYAB laser with GaAs Saturable Absorber

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shengzhi(赵圣之); ZHENG Jiaan(郑加安); CHEN Lei(陈磊); CHENG Zhenxiang(程振祥); CHEN Huanchu(陈焕矗)

    2002-01-01

    By using a passive Q-switch with GaAs saturable absorber, the Q-switched self-frequency doubling NYAB laser at 0.531μm has been successfully realized. The pulse width and the single pulse energy are measured. The numerical solutions of the coupling wave rate equations are in agreement with the experimental results.

  14. In-band pumped Q-switched polycrystalline Er:YAG ceramic laser at 1617 and 1634 nm

    Science.gov (United States)

    Wang, Yong; Zhao, Ting; Yang, Xiaofang; Shen, Deyuan; Zhang, Jian; Tang, Dingyuan

    2017-09-01

    We report on the performance of an Er,Yb fiber laser in-band pumped, acousto-optically Q-switched polycrystalline Er:YAG ceramic laser operating at 1617 and 1634 nm wavelength regions. A volume Bragg grating was employed to control the laser oscillating at either 1617 or 1634 nm via adjusting the incidence angle on the VBG of laser beams in the cavity. Spectral bandwidths of less than 0.1 nm were observed for both 1617 and 1634 nm wavelength laser emission. Stable pulses are generated for 0.1-10 kHz repetition rates. Maximum pulse energies of 6 mJ and 2.16 mJ were obtained for 1617 and 1634 nm under100 Hz repetition rate with pulse durations of 72 ns and 142 ns, respectively.

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

    Science.gov (United States)

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

    2017-09-01

    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.

  16. Hybrid Q-switched laser with MoSsub>2sub> saturable absorber and AOM driven sub-nanosecond KTP-OPO.

    Science.gov (United States)

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao

    2017-02-20

    Two-dimensional (2D) materials, especially transition-metal dichalcogenides, such as molybdenum disulfide (MoSsub>2sub>) and tungsten disulfide (WSsub>2sub>), have attracted great interests due to their exceptional optical properties as saturable absorbers in laser systems. In this work, at first, we presented a diode-pumped passively Q-switched laser with MoSsub>2sub> saturable absorber (MoSsub>2sub>-SA). At an incident pump power of 6.54 W, a maximum output power of 1.15 W with a minimum pulse duration of 70.6 ns was obtained, which is the shortest pulse duration of diode pumped passively Q-switched laser with MoSsub>2sub>-SA to the best of our knowledge. Then, by using a hybrid Q-switched laser with a MoSsub>2sub>-SA and an acousto-optic modulator (AOM) as pumping fundamental laser, a sub-nanosecond KTiOPOsub>4sub> (KTP) based intracavity optical parametric oscillation (IOPO) was realized. With an incident pump power of 10.2 W and AOM repetition rate of 10 kHz, the maximum output power of 183 mW with minimum pulse duration of 850 ps was obtained. The experimental results indicate that the IOPO pumped by the hybrid Q-switched laser with AOM and MoSsub>2sub>-SA can generate signal wave with shorter pulse duration than those IOPOs pumped by hybrid Q-switched laser with AOM and Cr4+:YAG or single-walled carbon nanotube saturable absober (SWCNT-SA) or monolayer graphene SA.

  17. Corneal shrinkage induced by nonmechanical Q-switched erbium:YAG laser trephination for penetrating keratoplasty in porcine eyes.

    Science.gov (United States)

    Stojkovic, Milenko; Seitz, Berthold; Küchle, Michael; Langenbucher, Achim; Viestenz, Arne; Viestenz, Anja; Hofmann-Rummelt, Carmen; Naumann, Gottfried O H

    2003-08-01

    To assess the degree of corneal diameter shrinkage induced by Q-switched mid-infrared laser corneal trephination for penetrating keratoplasty in an experimental model. Corneal trephination was performed in 80 enucleated porcine eyes fixed in a holder centered on an automated globe rotation device, by Q-switched (2.94 microm) Er:YAG laser along open masks. Four types of masks were used to protect the underlying corneal tissue: metal masks (donor and recipient) and ceramic masks (donor and recipient). Two spot diameters (0.65 mm and 0.96 mm) were combined with two energy settings (40 mJ/pulse and 50 mJ/pulse) for each of the masks used. Repetition rate was fixed at 5 Hz. Diameters of donor buttons/recipient beds (horizontal and vertical) were measured immediately after the trephination and compared to the given mask size. Minimum corneal shrinkage was found in the recipient metal mask group (mean +/- SD=0.3+/-0.4%) with 50 mJ pulse energy and 0.65 mm spot diameter (in the horizontal diameter), while the maximum shrinkage (5.3+/-2.8%) was found in the donor metal mask group with 50 mJ pulse energy and 0.96 mm spot diameter. Corneal shrinkage was less pronounced in recipient beds than in donor buttons (P0.05). Mean induced corneal diameter discrepancies between the donor button and the recipient bed (with metal and ceramic masks) were 2.5% and 2.5% in vertical diameter and 3.4% and 2.4% in horizontal diameter. The Q-switched Er:YAG laser experimental corneal trephination for penetrating keratoplasty may induce minor degrees of corneal diameter shrinkage in donor buttons and recipient openings. Oversizing of donor masks by 0.25-0.35 mm (i.e. 3-4% of graft size) may be a valid option to avoid refractive consequences.

  18. Acousto-optic Q-switched laser performances of Er3+∶yb3+∶LuAl3(BO3)4 crystal at 1.5-1.6 μm

    Institute of Scientific and Technical Information of China (English)

    Yujin Chen; Yanfu Lin; Haiyong Zhu; Ge Zhang; Yidong Huang

    2012-01-01

    Diode-pumped acousto-optic Q-switched pulse laser at 1.5-1.6μm is obtained in an Er3+:Yb3+:LuAl3 (BO3)4 crystal. Single-pulse laser operation with slope efficiency of 14% and threshold of approximately 100 mW is realized at an average absorbed pump power of 314 mW and repetition frequency of 20 kHz. Output pulse energy is 67 μJ. The effects of pulse repetition frequency, absorbed pump power, and duty cycle on the wavelength and pulse profile of the Q-switched Er3+:Yb3+:LuAl3(BO3)4 laser are also investigated.%Diode-pumped acousto-optic Q-switched pulse laser at 1.5-1.6 μm is obtained in an Er3+∶Yb3+∶LuAl3 (BO3)4 crystal.Single-pulse laser operation with slope efficiency of 14% and threshold of approximately 100 mW is realized at an average absorbed pump power of 314 mW and repetition frequency of 20 kHz.Output pulse energy is 67 μJ.The effects of pulse repetition frequency,absorbed pump power,and duty cycle on the wavelength and pulse profile of the Q-switched Er3+∶yb3+∶LuAl3(BO3)4 laser are also investigated.

  19. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

    Science.gov (United States)

    Radmanesh, Mohammad; Rafiei, Zohreh

    2015-04-01

    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.

  20. Q-switched ruby laser in cosmetic dermatology

    Science.gov (United States)

    Kopera, Daisy

    1996-12-01

    The q-switched ruby laser has shown promising results in the treatment of blue and black tattoos. The red light of the ruby laser, 694 nm wavelength, selectively absorbed by dark pigments, is converted into heat and pigments are immediately vaporized. Energy levels range between 4, 5 and 12 J/cm2. Short exposure time does not exceed the thermal relaxation time of the target structures. Thus, thermal damage of the surrounding tissue is minimal. Not only exogenous pigment as tattoo ink but also physiological pigmented structures as melanocytes, melanosome loaden keratinocytes, and melanophages are affected by this type of laser application. Therefore the ruby laser represents a new option in the treatment of a variety of benign pigmented lesions in cosmetic dermatology. The benefit of this source can be seen in efficient clearing of the lesions without scarring. As a side effect transient hypopigmentation may occur. Ruby laser treatment of melanocytic lesions cannot be recommended because unpigmented nevus cells do not absorb red light and persist unaltered. They still bear the potency of further transformation, as into malignancy.

  1. Q-switched erbium:YAG laser corneal trephination: thermal damage in corneal stroma and cut regularity of nonmechanical Q-switched erbium:YAG laser corneal trephination for penetrating keratoplasty.

    Science.gov (United States)

    Stojkovic, M; Seitz, B; Langenbucher, A; Viestenz, A; Viestenz, A; Hofmann-Rummelt, C; Schlötzer-Schrehardt, U; Küchle, M; Naumann, G O H

    2004-01-01

    To assess stromal thermal damage and cut regularity induced by nonmechanical Q-switched Er:YAG laser corneal trephination for penetrating keratoplasty. Corneal trephination was performed in 80 enucleated porcine eyes by Q-switched (2.94-microm) Er:YAG laser, along with donor and recipient masks made of metal or ceramic. All combinations of 0.65- or 0.96-mm spot diameter and 45- or 50-mJ/pulse energy setting were used with each of the masks at a 5-Hz repetition rate. Corneas were processed for histologic examinations. Stromal thermal damage was quantified on PAS-stained slides, and cut regularity was assessed semiquantitatively on a scale from 0 (regular) to 3 (highly irregular). Transmission electron microscopy and scanning electron microscopy were performed on selected specimens. The least thermal damage (mean +/- SD = 6.2 +/- 0.7 microm) was found in the donor ceramic group with 50-mJ/pulse energy and 0.65-mm spot diameter, while the best regularity of the cut (1.2 +/- 0.4) was found in the donor ceramic group with 45-mJ pulse energy and 0.65-mm spot diameter. Thermal damage was less pronounced in donor than in recipient corneas (P trephination for nonmechanical penetrating keratoplasty, reproducible high cut regularity and low concomitant thermal damage were observed. This is an encouraging finding in the search for a nonmechanical trephine for penetrating keratoplasty combining high precision and low cost.

  2. Tunable Fe(2+):ZnSe passively Q-switched Ho(3+)-doped ZBLAN fiber laser around 3 μm.

    Science.gov (United States)

    Li, Jianfeng; Luo, Hongyu; Wang, Lele; Zhai, Bo; Li, Heping; Liu, Yong

    2015-08-24

    We report a tunable passively Q-switched Ho(3+)-doped ZBLAN fiber laser at 3 μm waveband using a Fe(2+):ZnSe crystal as saturable absorber (SA) and a plane ruled grating in Littrow configuration as wavelength tuning element. Stable pulse trains with ~85 nm tuning range from 2919.1 nm to 3004.2 nm and spectrum bandwidths of ~1 nm were achieved for the Fe(2+):ZnSe crystal with an initial transmission (IT) of 69%. Pulse duration increased from 1.23 μs to 2.35 μs and repetition rate decreased from 96.1 kHz to 43.56 kHz with the extension towards long wavelength direction. With the IT increasing to 79% and then 89%, though the available tuning range was slightly shortened, higher output power, pulse energy and slope efficiency were obtained with the slightly increased pulse duration and repetition rate. Maximum output power of 337 mW at a slope efficiency of 11.44% and pulse energy of 5.64 μJ were achieved at ~2970 nm and ~2991 nm, respectively. High signal noise ratio (SNR) of over 50 dB across the whole tuning range for the three ITs Fe(2+):ZnSe crystals indicated the stable Q-switching. To our knowledge, this is the first reported wavelength tunable passively Q-switched ZBLAN fiber laser.

  3. 2.3-μm Tm3+:YLF laser passively Q-switched with a Cr2+:ZnSe saturable absorber.

    Science.gov (United States)

    Canbaz, Ferda; Yorulmaz, Ismail; Sennaroglu, Alphan

    2017-05-01

    We report, what is to our knowledge, the first passively Q-switched operation of a 2.3-μm Tm3+:YLF laser by using a Cr2+:ZnSe saturable absorber. In the experiments, a tunable Ti3+:sapphire laser was used to end pump the Tm3+:YLF gain medium inside an x cavity. A Cr2+:ZnSe saturable absorber was also included in the cavity to initiate passive Q switching. At all pump power levels above lasing threshold, passively Q-switched operation of the Tm3+:YLF laser could be obtained at 2309 nm with pulse durations and repetition frequencies in the ranges of 1.2-1.4 μs and 0.3-2.1 kHz, respectively. Analysis of power dependent repetition rate data further gave an estimated value of 3.1% for the round-trip saturable loss of the Cr2+:ZnSe saturable absorber.

  4. Silver nanoparticle-film based saturable absorber for passively Q-switched erbium-doped fiber laser (EDFL) in ring cavity configuration

    Science.gov (United States)

    Ahmad, H.; Ruslan, N. E.; Ismail, M. A.; Ali, Z. A.; Reduan, S. A.; Lee, C. S. J.; Harun, S. W.

    2016-09-01

    We report a passive Q-switched erbium-doped fiber laser based on silver (Ag) nanoparticle thin-film saturable absorber (SA). The thin film was sandwiched between two fiber ferrules, which offer flexibility and easy integration into the ring cavity. Self-started and stable Q-switching is achieved at a central wavelength of 1558.7 nm within the C-band region. The repetition rate and pulse duration shows a typical Q-switched laser profile as we increase the pump power; the repetition rate increases from 19.471-74.074 kHz while pulse duration decreases from 8.88-3.2 µs. A signal-to-noise ratio value of 35 dB was obtained at 100 mW pump power. By using a balanced twin-detector method, the modulation depth and saturation intensity of the Ag nanoparticle thin film were measured to be 31.6% and 0.54 MW cm-2 respectively. This result offers another alternative to the existing SA materials.

  5. Development of monolith Nd:YAG /Cr+4:YAG passively Q-switched microchip laser

    Science.gov (United States)

    Izhnin, Ihor; Vakiv, Mykola; Izhnin, Aleksandr; Syvorotka, Igor; Ubizskii, Sergii; Syvorotka, Ihor, Jr.

    2005-09-01

    The main features of passively Q-switched microchip lasers development are considered. The active medium of laser is an epitaxial structure combining an epitaxial layer of saturable absorber Cr4+:Y3Al5O12 (Cr:YAG) grown on substrate of generating crystal Nd:YAG by liquid phase epitaxy. The modulator layer has an initial optical absorption of 36 cm-1 at wavelength of lasing (1064 nm). The epitaxial layer grown on unworking side was mechanically removed and this substrate side was optically polished. The other one was processed precisely to needed thickness. The cavity's mirrors were deposited by electron beam technique directly on each side of the structure to form a rugged, monolithic resonator. Diode laser Model ATC-C4000 with lasing wavelength 808 nm provided the CW end pumping. The output pulses parameters were investigated by means of test bench consisting of photoelectric transducer FEK-15 and Digital Phosphor Oscilloscope TDS 5052B. The obtained laser parameter are as follows: pulse width (FWHM) about 1.3 ns, repetition rate 5.5 kHz, average output power about 10 mW, pulse energy 1.0 μJ, pick power 1.2 kW. The possible solutions for laser parameter improving and optimization are discussed.

  6. A passively Q-switched Ho:YVO4 Laser at 2.05 μm with Graphene Saturable Absorber

    Directory of Open Access Journals (Sweden)

    Wenmiao Lin

    2016-05-01

    Full Text Available We report a passively Q-switched Ho:YVO4 laser pumped at 1.94 µm with multilayer graphene as a saturable absorber. At the absorbed pump power of 9.3 W, the maximum average output power of 2.2 W was obtained in Ho:YVO4 laser with minimum pulse width of 265.2 ns and pulse repetition rate of 131.6 kHz at 2052.1 nm. In addition, a beam quality factor of M2~1.7 was measured at the maximum output level. This is, as far as we know, the first time that graphene has been used in a passively Q-switched Ho:YVO4 laser.

  7. Study of a high output coupling ratio Q-switched erbium-doped fibre laser using MoS2 saturable absorber

    Science.gov (United States)

    Chong, W. Y.; Yap, Y. K.; Behameen, S.; Ahmad, H.

    2017-02-01

    In the work here, the performance of a Q-switched erbium-doped fibre laser using a MoS2 saturable absorber and operating with a high output coupling ratio has been studied. It is found that the pump conversion efficiency for the higher output coupling ratio is higher in the current setup. Q-switched laser oscillation is observed over the set wavelength range from 1525-1565 nm with a maximum pulse energy of ~0.50 µJ achieved at a pump power of ~83 mW, corresponding to a maximum peak power of ~186 mW. With lower intra-cavity laser intensity achieved using the higher output coupling ratio, the second order absorption of the MoS2 is mitigated. However, scaling of the peak power and pulse energy seems to be limited by the interplay between the pulse duration, pulse energy and repetition rate.

  8. All-fiber passively Q-switched 604  nm praseodymium laser with a Bisub>2sub>Sesub>3sub> saturable absorber.

    Science.gov (United States)

    Lin, Hui-Yu; Li, Wen-Song; Lan, Jing-Long; Guan, Xiao-Feng; Xu, Hui-Ying; Cai, Zhi-Ping

    2017-02-01

    We experimentally demonstrated a simple passively Q-switched praseodymium (Pr3+)-doped all-fiber laser at 604 nm with a Bisub>2sub>Sesub>3sub> saturable absorber (SA). A Bisub>2sub>Sesub>3sub>/polyvinyl alcohol composite film is sandwiched between two ferrules to construct a fiber-compatible Q-switcher. Two fiber end facet mirrors build a compact-linear resonator. The repetition rate of the achieved 604 nm Q-switching pulse can be widely tuned from 86.2 to 187.4 kHz, and the pulse duration can be as narrow as 494 ns. To the best of our knowledge, this is the shortest operation wavelength of a Bisub>2sub>Sesub>3sub>-based pulsed all-fiber laser at 604 nm.

  9. Passively Q-switched Single-longitudinal-mode c-cut Nd:GdVO4 laser with a twisted-mode cavity.

    Science.gov (United States)

    Pan, Haifeng; Xu, Shixiang; Zeng, Heping

    2005-04-04

    Single-longitudinal-mode operation is achieved in a twisted-mode-cavity c-cut Nd:GdVO4 laser. With a semiconductor saturable absorption mirror as an intracavity saturable absorber to launch passive Q-switching, no mode-locked spikes are observed on the temporal envelopes of the Q-switched output pulses due to the complete elimination of spatial hole burning in the gain medium to suppress longitudinal multi-modes. The maximal average output power is 1.24 W with the repetition rate of 76.3 kHz, and the single pulse energy is 16.0 microJ. The pulse width and polarization ratio of the output laser beam are measured about 150 ns and 53:1, respectively.

  10. Nickel oxide nanoparticles as a saturable absorber for an all-fiber passively Q-switched erbium-doped fiber laser

    Science.gov (United States)

    Nady, A.; Ahmed, M. H. M.; Latiff, A. A.; Numan, A.; Ooi, C. H. Raymond; Harun, S. W.

    2017-06-01

    Nickel oxide (NiO) nanoparticles were synthesized by a facile sonochemical method to fabricate saturable absorber (SA) composite film with a modulation depth of 39% and saturation intensity of 0.025 MW cm-2. By inserting the NiO SA into a laser cavity, a stable Q-switched operation is achieved at 1561.2 nm. The laser has a pump threshold of 25 mW, a pulse repetition rate tunable from 19.57 to 52.18 kHz, a high signal-to-noise ratio of 55 dB and a minimum pulse duration of 5.2 µs. Such results imply that NiO nanoparticles are a comparable candidate for an SA in passively Q-switched fiber lasers at a low pump intensity. To the best of our knowledge, this is the first demonstration of a fiber laser based on NiO SA.

  11. Self-organization of the Q-switched mode-locked regime in a diode-pumped Nd:YAG laser

    Science.gov (United States)

    Donin, V. I.; Yakovin, D. V.; Gribanov, A. V.

    2015-06-01

    A new Q-switched mode-locked generation regime of a solid-state laser, in which a Q-switch is "spontaneously" formed at the frequency of relaxation oscillations, has been observed for the first time. The new generation has been implemented by means of the previously proposed method of an acoustic modulator of a traveling wave in combination with a spherical mirror of a cavity. Stable pulse trains with a repetition frequency of ~30 kHz and a duration of ~2 µs have been observed in the diode-pump Nd:YAG laser with an average output power of ~3 W. Each train contains about 200 equispaced single pulses with a duration of ~45 ps.

  12. Performance enhancement of sub-nanosecond diode-pumped passively Q-switched Yb:YAG microchip laser with diamond surface cooling.

    Science.gov (United States)

    Zhuang, W Z; Chen, Yi-Fan; Su, K W; Huang, K F; Chen, Y F

    2012-09-24

    We experimentally confirm that diamond surface cooling can significantly enhance the output performance of a sub-nanosecond diode-end-pumped passively Q-switched Yb:YAG laser. It is found that the pulse energy obtained with diamond cooling is approximately 1.5 times greater than that obtained without diamond cooling, where a Cr(4+):YAG absorber with the initial transmission of 84% is employed. Furthermore, the standard deviation of the pulse amplitude peak-to-peak fluctuation is found to be approximately 3 times lower than that measured without diamond cooling. Under a pump power of 3.9 W, the passively Q-switched Yb:YAG laser can generate a pulse train of 3.3 kHz repetition rate with a pulse energy of 287 μJ and with a pulse width of 650 ps.

  13. 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)

    2016-08-15

    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)

  14. Watt-level passively Q-switched double-cladding fiber laser based on graphene oxide saturable absorber.

    Science.gov (United States)

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

    2013-10-10

    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.

  15. Plate-shaped Yb:LuPO4 crystal for efficient CW and passively Q-switched microchip lasers

    Science.gov (United States)

    Liu, Junhai; Wang, Lisha; Han, Wenjuan; Xu, Honghao; Zhong, Degao; Teng, Bing

    2016-10-01

    It is demonstrated that plate-shaped crystals of Yb:LuPO4, which are grown from spontaneous nucleation by high-temperature solution method, can be utilized to make microchip lasers operating in continuous-wave (CW) or passively Q-switched mode. Efficient operation of such a microchip laser, which is built with a 0.3 mm thick crystal plate in a 2 mm long plane-parallel cavity, is realized at room temperature. With 2.37 W of pump power absorbed, 1.45 W of CW output power is generated with a slope efficiency of 73%. When passively Q-switched with a Cr4+:YAG crystal plate as saturable absorber, the laser produces a maximum pulsed output power of 0.53 W at 1013.3 nm, at a pulse repetition rate of 23.8 kHz, the resulting pulse energy, duration, and peak power are 22.3 μJ, 4.0 ns, and 5.6 kW, respectively.

  16. Tandem-pumped 1120-nm actively Q-switched fiber laser

    Institute of Scientific and Technical Information of China (English)

    王建华; 胡金萌; 张世强; 陈露璐; 房勇; 冯衍

    2015-01-01

    We report on a tandem-pumped actively Q-switched fiber laser system emitting at 1120 nm. Parasitic oscillation is challenging in Yb-doped Q-switched 1120-nm fiber laser, which is suppressed by pumping with a fiber laser at 1018 nm. At least 4 times improvement in output peak power is demonstrated in a single laser setup with 1018-nm fiber laser pumping instead of 976-nm laser diode pumping. This is, to the best of our knowledge, the first demonstration of a tandem-pumped Q-switched fiber laser.

  17. Green Output of 1.5 W from a Diode-Pumped Intracavity Frequency-Doubled Self-Q-Switched and Mode-Locked Cr,Nd:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    DU Shi-Feng; WANG Su-Mei; ZHANG Dong-Xiang; LI De-Hua; ZHANG Zhi-Guo; FENG Bao-Hua; ZHANG Shi-Wen

    2007-01-01

    We report a diode-pumped intracavity frequency-doubled self-Q-switched and mode-locked Cr,Nd:YAG/KTP green laser with a Z-type cavity, which produces 1.5 W of average power at 532 nm with incident pump power 14.2 W. The individual mode-locked green pulse duration is about 560ps with 149MHz repetition rate. Almost 100% modulation depth of the mode-locked green pulses is achieved at an incident pump power of 4.13 W. The maximum energy of Q-switched green pulse is 19.8 fiJ. The experimental results of pulse duration and pulse energy of Q-switched green pulse agree well with the theoretical calculations.

  18. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Calculation of mass transfer in the remote cutting of metals by radiation of a high-power repetitively pulsed CO2 laser

    Science.gov (United States)

    Gladush, G. G.; Rodionov, N. B.

    2002-01-01

    The mechanism of remote cutting of steel plates by radiation of a high-power repetitively pulsed CO2 laser is theoretically studied. The models of melt removal by the gravity force and the recoil pressure of material vapour are proposed and the sufficient conditions for the initiation of cutting are determined. A numerical model of a thermally thin plate was employed to describe the cutting for large focal spots.

  19. Diode-pumped double passively Q-switched Nd:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    LIU Min; LIU Shu-shan; LI Lei; WANG Wei-wei; CHEN Fei; LIU Jie

    2008-01-01

    Through using both Cr4+:YAG and GaAs saturable absorbers, a diode-pumped double passively Q-switched Nd:GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.

  20. Laser-Tissue Interaction in Tattoo Removal by Q-Switched Lasers

    OpenAIRE

    2015-01-01

    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 ...

  1. Comparison of laser performance of electro-optic Q-switched Nd:YAG ceramic/single crystal laser

    Institute of Scientific and Technical Information of China (English)

    Jianghua Ji; Xiaolei Zhu; Chunyu Wang; Yongwei Feng; Qihong Lou

    2006-01-01

    @@ An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated.Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2was about 1.4.

  2. Intracavity-Doubled Self-Q-Switched Nd,Cr:YAG 946/473 nm Microchip Laser

    Institute of Scientific and Technical Information of China (English)

    李德华; 刘安汉; 沈德忠; 王凌; 高春清; 张治国; 冯宝华; Volker Gaebler; 刘百宁; H.J.Eichler; 张世文

    2002-01-01

    We carried out the operation of an intracavity frequency-doubled self-Q-switched Nd, Cr: YA G /KNbO3 946/473 nm microchip laser pumped by a Ti:sapphire laser. The overall cavity length was about 4 mm. The maximum average blue pover of 12mW was achieved with a repetition rate of 13 kHz at an absorbed pump power of 545mW. The pulses of the 473nm laser had a duration of 7ns and a peak power of 132 W at this pump level. The conversion efficiency was 2.2% with respect to the absorbed pump power of a 808nm laser.

  3. Intrinsic reduction the depolarization loss in electro-optical Q-switched laser using a rectangular KD*P crystal

    Science.gov (United States)

    Yin, Xingliang; Jiang, Menghua; Sun, Zhe; Hui, Yongling; Lei, Hong; Li, Qiang

    2017-09-01

    We presented the first demonstration of a new structure KD*P crystal as electro-optic switch, in which the thermal depolarization loss was intrinsically reduced. The thermally induced birefringence and depolarization of both cylindrical and rectangular crystalline structure were simulated. The higher pulse energy or average power output was achieved in the diode pumped E-O Q-switched laser using a rectangular KD*P crystal. At the repetition rate of 100 Hz, the maximum average output power was 27.2 W at 145 A pump current, corresponding to the pulse energy was 272 mJ with pulse width of 65 ns and the beam quality of M2=20.4. Comparing the highest average power or corresponding single pulse energy, the laser with the rectangular KD*P crystal was two times of the laser with the traditional cylindrical KD*P crystal.

  4. Passively Q-switched 1.33 μm Nd:GAGG laser with Co2+:LMA saturable absorber

    Science.gov (United States)

    Zuo, C.-H.; Zhang, B.-T.; He, J.-L.

    2011-11-01

    In this paper, with Co2+:LaMgAl11O19 (Co2+:LMA) crystals as the saturable absorber, the efficient passively Q-switched laser performance of a diode-end-pumped Nd:Gd3AlxGa5-xO12 (Nd:GAGG) laser at 1.33 μm has been realized. Under the absorbed pump power of 8.2 W, a maximum average output power of 450 mW was recorded with a Co2+:LMA crystal with an initial transmission of 90%. The minimum pulse duration was 14.6 ns, corresponding to the repetition rate of 3 kHz, the single pulse energy of 110 μJ and the pulse peak power of 7.1 kW.

  5. 1.06 {\\mu}m Q-switched ytterbium-doped fiber laser using few-layer topological insulator Bi2Se3 as a saturable absorber

    CERN Document Server

    Luo, Zhengqian; Weng, Jian; Cheng, Huihui; Lin, Zhiqin; Cai, Zhiping; Xu, Huiying

    2013-01-01

    Passive Q-switching of an ytterbium-doped fiber (YDF) laser with few-layer topological insulator (TI) is, to the best of our knowledge, experimentally demonstrated for the first time. The few-layer TI: Bi2Se3 (2-4 layer thickness) is fabricated by the liquid-phase exfoliation method, and has a low saturable optical intensity of 53 MW/cm2 measured by the Z-scan technique. The optical deposition technique is used to induce the few-layer TI in the solution onto a fiber ferrule for successfully constructing the fiber-integrated TI-based saturable absorber (SA). By inserting this SA into the YDF laser cavity, stable Q-switching operation at 1.06 {\\mu}m is achieved. The Q-switched pulses have the shortest pulse duration of 1.95 {\\mu}s, the maximum pulse energy of 17.9 nJ and a tunable pulse-repetition-rate from 8.3 to 29.1 kHz. Our results indicate that the TI as a SA is also available at 1 {\\mu}m waveband, revealing its potential as another wavelength-independent SA (like graphene).

  6. Widely-tunable, passively Q-switched erbium-doped fiber laser with few-layer MoS2 saturable absorber.

    Science.gov (United States)

    Huang, Yizhong; Luo, Zhengqian; Li, Yingyue; Zhong, Min; Xu, Bin; Che, Kaijun; Xu, Huiying; Cai, Zhiping; Peng, Jian; Weng, Jian

    2014-10-20

    We propose and demonstrate a MoS2-based passively Q-switched Er-doped fiber laser with a wide tuning range of 1519.6-1567.7 nm. The few-layer MoS2 nano-platelets are prepared by the liquid-phase exfoliation method, and are then made into polymer-composite film to construct the fiber-compatible MoS2 saturable absorber (SA). It is measured at 1560 nm wavelength, that such MoS2 SA has the modulation depth of ∼ 2% and the saturable optical intensity of ∼ 10 MW/cm(2). By further inserting the filmy MoS2-SA into an Er-doped fiber laser, stable Q-switching operation with a 48.1 nm continuous tuning from S- to C-waveband is successfully achieved. The shortest pulse duration and the maximum pulse energy are 3.3 μs and 160 nJ, respectively. The repetition rate and the pulse duration under different operation conditions have been also characterized. To the best of our knowledge, it is the first demonstration of MoS2 Q-switched, widely-tunable fiber laser.

  7. Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber laser at 2.8 {\\mu}m

    CERN Document Server

    Qin, Zhipeng; Zhang, Han; Zhao, Chujun; Yuan, Peng; Wen, Shuangchun; Qian, Liejia

    2015-01-01

    Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multi-layer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 {\\mu}m. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 {\\mu}J/cm2, respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 {\\mu}J and pulse width of 1.18 {\\mu}s at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-{\\mu}m fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.

  8. Low Fluence Q-Switched Nd: YAG Laser Toning and Q-Switched Ruby Laser in the Treatment of Melasma:A Comparative Split-Face Ultrastructural Study

    Science.gov (United States)

    Yamashita, Rie; Kawana, Seiji; Sato, Shigeru; Naito, Zenya

    2012-01-01

    Background: Melasma still presents as a difficult entity to treat, especially in the Asian skin phe-notype. Recently laser toning with the Q-switched Nd:YAG has attracted attention. The present study investigated the efficacy of Q-switched Nd:YAG laser toning for melasma, with a histopathological comparison with the Q-switched ruby laser. Subjects and Methods: Eight Japanese females (41–57 yr, mean 52.5 yr) with Fitzpatrick skin type III and bilateral melasma participated in the study. One half of each subject's face (randomly chosen) was treated with Q-switched 1064 nm Nd:YAG laser toning (pulse width 5–20 ns; spot size, 6 mm diameter; fluence, 3.0 J/cm2, 5–7 passes, once/week, 4 weeks: QS:YAG group), and the contralateral half with a single treatment using a Q-switched ruby laser (694.5 nm, pulse width 20 ns, spot size 4 mm diameter; fluence 4.0 J/cm2, 1 pass with approximately 20% overlap: QS:Ruby group). Skin biopsies were taken immediately after the 4th Nd:YAG session and the single ruby session, and histopathological comparison was performed with light- and transmission electron microscopy (TEM). Results: Improvement in melasma pigmentation was seen in both the QS:YAG- and QS:Ruby-treat-ed sides, and this was well-maintained in the QS:YAG group. Ultrastructurally, melanin granules were destroyed in both groups, but there was considerably more morphological epidermal and dermal damage in the QS:Ruby specimens compared with minimal epidermal disruption and cellular damage in the QS:YAG specimens. Conclusions: Q-switched 1064 nm Nd:YAG laser toning offered superior results in the treatment of melasma in the Japanese skin type compared with the Q-switched ruby laser, both ultrastructurally with less immediately post-treatment cellular damage and macroscopically, and a longer recurrence-free interval. PMID:24610976

  9. Near-diffraction-limited green source by frequency doubling of a diode-stack pumped Q-switched Nd:YAG slab oscillator-amplifier system.

    Science.gov (United States)

    Zhang, Hengli; Liu, Xiaomeng; Li, Daijun; Shi, Peng; Schell, Alex; Haas, Claus Rüdige; Du, Keming

    2007-09-10

    A near-diffraction-limited, stable, 18 mJ green source with a pulse width of 16.7 ns was generated at a 1 kHz repetition rate by frequency doubling of diode stacks end-pumped electro-optically Q-switched slab Nd:YAG oscillator-amplifier system. The pump to green optical conversion efficiency was 10.7%. At the output energy of 15 mJ at 532 nm, the M2 factors were 1.3 and 1.7 in the unstable and stable directions, respectively. The energy pulse stability was approximately 0.8%.

  10. Diode-pumped passively dual-wavelength Q-switched Nd:GYSGG laser using graphene oxide as the saturable absorber.

    Science.gov (United States)

    Song, Qi; Wang, Guoju; Zhang, Bingyuan; Wang, Wenjun; Wang, Minghong; Zhang, Qingli; Sun, Guihua; Bo, Yong; Peng, Qinjun

    2015-04-01

    The performance of a diode end-pumped passively Q-switched dual-wavelength Nd:GYSGG laser operating at 1057.28 and 1060.65 nm with graphene oxide as the saturable absorber was demonstrated. The maximum dual-wavelength average output power of 521 mW was achieved under the absorbed pump power of 5.4 W, corresponding to the optical-to-optical conversion and slope efficiency of 9.8% and 21%, respectively. The minimum pulse width was 115 ns with a pulse repetition rate of 338 kHz.

  11. 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

    2011-12-01

    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

  12. A Diode-Stack End-Pumped Electro-Optically Q-Switched Nd:YAG Slab Oscillator-Amplifier System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-Li; YAN Ying; LI Dai-Jun; SHI Peng; DU Ke-Ming

    2008-01-01

    A laser diode-stack end-pumped electro-optically Q-switched Nd:YAG slab oscillator-amplifier system with near-diffraction-limited output is demonstrated by a stable-unstable hybrid resonator. The average power of 100 W at a repetition rate or 10kHz with a pulse width 14.7ns and average power of 76.3 W at a repetition rate of 5kHz with a pulse width of 10.2ns are measured. At the repetition rate of 10 kHz and at an output power of 89 W, the beam quality factors M2 in the unstable and stable directions are 1.3 and 1.5, respectively.

  13. Side-pumped neodymium slab lasers Q-switched by V:YAG on 1.3μm

    Science.gov (United States)

    Jabczyński, Jan K.; Żendzian, Waldemar; Kwiatkowski, Jacek; Šulc, Jan; Němec, Michal; Jelínkova, Helena

    2006-02-01

    Nd:YAG and Nd:YAP crystals in form of triangle which makes possible to realize a slab side-pumped configuration with one total internal reflection were tested as an active media for diode-pumped laser. The resonator arrangements for Q-switched regime were prepared for the emission corresponding to Nd 3+ ion transition 4F 3/2--> 4I 13/2 referring to each crystal (λ= 1318 nm Nd:YAG and λ= 1342 nm Nd:YAP). Optical pumping was accomplished by a fast axis collimated quasi-CW diode DILAS E7Y1-808.3-600Q-H175V with peak power 600 W. Pumping radiation was focused by two plan-convex lenses into an active medium. The parameters of the pumping radiation were: wavelength 806nm, maximum pumping energy was 150mJ, pulse length 250μs, repetition rate up to 14 Hz. In free running regime the maximum reached energy was 24 mJ and 27.5 mJ for Nd:YAG and Nd:YAP, respectively. The corresponding obtained slope efficiency was 19.9 % and 23.7 % for Nd:YAG and Nd:YAP laser oscillator, respectively. Proper Q-switching for 1.3 μm was realized with saturable absorber V:YAG which initial transmission was optimized for shortest possible pulse length. For that obtained pulses were 6 ns with the energies 740 μJ and 432 μJ for Nd:YAG and Nd:YAP, respectively. This results correspond to peak power reached 125 kW (Nd:YAG), and 77 kW (Nd:YAP) in fundamental TEM 00 mode which allows this laser to be used as an efficient source for further nonlinear conversion or other applications.

  14. Growth and characterization of self-Q-switched Nd:Cr:YVO4 crystal.

    Science.gov (United States)

    Pan, Z B; Yao, B; Yu, H H; Xu, H H; Wang, Z P; Wang, J Y; Zhang, H J

    2012-01-30

    A Nd:Cr:YVO4 crystal was grown by the Czochralski method for the first time to our knowledge. Its structure and cell parameter have been studied by X-ray powder diffraction (XRPD) analysis. Polarized absorption spectra were measured at room temperature, which showed that the absorption bands display polarization character and an absorption band of Cr5+ ions at 1110 nm enables the crystal to be a self-Q-switched laser material. We also found that the absorption of Cr5+ ions became much larger and its self-Q-switched laser performance became much better when the Nd:Cr:YVO4 crystal was annealed because the annealing induces more Cr ions to become those with + 5 valence. In the self-Q-switched laser, the maximum output power, shortest pulse width, and largest pulse energy were obtained to be 120 mW, 85.8 ns, and 0.79 μJ, respectively.

  15. Continuous-wave and actively Q-switched Nd:LSO crystal lasers

    Science.gov (United States)

    Zhuang, S.; Li, D.; Xu, X.; Wang, Z.; Yu, H.; Xu, J.; Chen, L.; Zhao, Y.; Guo, L.; Xu, X.

    2012-04-01

    With a fiber coupled laser diode array as the pump source, Nd-doped Lu2SiO5 (Nd:LSO) crystal lasers at 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions were demonstrated. The active Q-switched dual-wavelength lasers at about 1.08 μm, as well as continuous-wave (CW) and active Q-switched lasers at 1357 nm are reported for the first time, to the best of our knowledge. Considering the small emission cross-sections and long fluorescence lifetime, this material possesses large energy storage ability and excellent Q-switched properties. The special emission wavelength at 1357 nm will have promising applications to be used in many fields, such as THz generation, pumping of Cr3+:LiSAF, repumping of strontium optical clock, laser Doppler velocimeter and distributed fiber sensor.

  16. Simultaneous Q-switching and mode-locking in the CW Nd:YAG laser

    Science.gov (United States)

    Kuizenga, D. J.; Phillion, D. W.; Siegman, A. E.; Lund, T.

    1973-01-01

    The theory of transient mode-locking for an active modulator in a laser with a homogeneously broadened line is presented. The theory is applied to simultaneously Q-switched and mode-locked Nd:YAG lasers and good agreement between theory and experiment is obtained. The main conclusion is that under usual Q-switched operating conditions the mode-locking process does not have sufficient time to build up to steady-state conditions. We also present a method to overcome this problem by allowing the laser to prelase before the Q-switch is opened. Mode-locked pulses whose width approaches the steady-state value are obtained. The transient mode-locking theory presented here also applies to actively mode-locking TEA CO2 lasers and to other types of simultaneously pulsed and mode-locked lasers.

  17. Passive Q-switching of Yb bulk lasers by a graphene saturable absorber

    Science.gov (United States)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Liu, J.; Zhang, H.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2016-04-01

    Compact Yb:KLu(WO4)2 and Yb:LuVO4 lasers diode-pumped at 978 nm are passively Q-switched by a single-layer graphene saturable absorber. The Yb:KLu(WO4)2 laser generated 165 ns/0.49 μJ pulses at 1030 nm with 170 mW average output power and 12 % slope efficiency. With the Yb:LuVO4 laser, 152 ns/0.83 μJ pulses were achieved. The output power reached 300 mW at 1024 nm, and the slope efficiency was 10 %. Laser operation in a plano-plano cavity is achieved with both crystals with thermal lensing playing a key role in their performance. A model describing graphene Q-switched Yb lasers is developed. Our results indicate the potential of graphene for passive Q-switching of ~1 μm bulk lasers.

  18. Efficient tri-wavelength actively Q-switched Yb:GAGG laser

    Science.gov (United States)

    Zhao, Ruwei; Zhang, Baitao; Jia, Zhitai; Su, Xiancui; Lou, Fei; Zhang, Haikun; He, Jingliang; Liu, Fengqin

    2015-01-01

    An efficient acousto-optic Q-switched Yb-doped Gd3AlxGa5-xO12 (GAGG) (x = 0.5) laser is demonstrated. Under the absorbed pump power of 7.4 W, the maximum average output power of 1.4 W is obtained at the pulse repletion rate of 1 kHz , with the slope efficiency as high as 32%. The pulse width of 40 ns is achieved with the pulse energy and peak power of 1.4 mJ and 35 kW, respectively. What' more, the output spectrum shows itself tri-wavelength in either CW or Q-switching mode. To our knowledge, this is the first time for realizing simultaneous tri-wavelength Yb:GAGG laser actively Q-switched operation.

  19. Efficient use of Q-switched lasers in the treatment of cutaneous lesions

    Science.gov (United States)

    Hu, Xin-Hua

    1995-05-01

    The use of Q-switched laser has been well documented in the treatment of pigmented lesions, particularly in the tattoo removal. To better understand the ablation process by Q-switched lasers, we carried out an analysis on the states and other physical properties of certain tissue/pigment under the action of a strong transient electric field associated with the high energy nanosecond laser pulses. The dependence of the ablation threshold of transient electric field on the chromophore absorption has been found to be weak. A plasma ablation model is used to interpret previous experimental results. The comparison of the plasma model with the conventional selective photothermolysis model has led to a new design concept of Q-switched lasers for dermatology surgery.

  20. All-fiber dual-wavelength Q-switched and mode-locked EDFL by SMF-THDF-SMF structure as a saturable absorber

    Science.gov (United States)

    Latiff, A. A.; Kadir, N. A.; Ismail, E. I.; Shamsuddin, H.; Ahmad, H.; Harun, S. W.

    2017-04-01

    We demonstrate all-fiber dual-wavelength Q-switched and mode-locked erbium-doped fiber laser (EDFL) by utilizing the thulium-holmium-doped fiber (THDF) as a fiber saturable absorber (SA) and also a Mach-Zehnder interferometer (MZI) element. The 19 cm long THDF has a core diameter of 11.5 μm, refractive index difference of 0.005, and cutoff wavelength of 1810 nm. Stable dual-wavelength Q-switching operation was generated at 1555.14 nm and 1557.64 nm with free spectral range (FSR) of 2.5 nm. The repetition rate of 14.45-78.49 kHz was obtained between 12 and 100 mW pump power. At maximum pump power, the maximum output power and pulse energy were 2.58 mW and 32.87 nJ, respectively. By adding 195 cm long SMF in the same cavity, the stable dual-wavelength mode-locking operation was started at 166 mW and continue stable to 201 mW pump power. This mode-locking operation produced stable dual-wavelength pulses at 1530.34 nm and 1532.84 nm with a repetition rate of 1 MHz with a pulse duration of 128 ns and signal-to-noise ratio (SNR) of 62 dB. It shares the same value of FSR in Q-switching operation. The highest output power of 1.57 nJ corresponds to the maximum output power of 1.57 mW was obtained. Our results validate the linear absorption characteristic at C-band region and multimode fiber effect of THDF can be utilized as SA to generate stable all-fiber dual-wavelength pulsed lasers. Remarkably, these findings expand a fiber gain medium application in short pulse generation.

  1. Optimization Of Output Q-Switched Nd:YAG Laser Based On Switching Time

    Science.gov (United States)

    Tamuri, Abd Rahman; Daud, Yaacob Mat; Bidin, Noriah

    2010-07-01

    This paper reports the optimization of output Q-switch Nd:YAG. A free running Nd:YAG laser was employed as source of light. KD*P crystal was utilized as a Pockels cell. Avalanche transistor pulser was designed to switch a high voltage power supply. The switching time was conducted via a control unit based PIC16F84A microcontroller. The pulser was able to switch the voltage within 3 ns. The optimum switching time of Q-switching is obtained at 182.34 μs. The corresponding laser output is 40 mJ with pulse duration of 25 ns.

  2. Passive Q-switching of a Tm:YLF laser with a Co2+ doped silver halide saturable absorber

    Science.gov (United States)

    Hecht, Harel; Burshtein, Zeev; Katzir, Abraham; Noach, Salman; Sokol, Maxim; Frumker, Eugene; Galun, Ehud; Ishaaya, Amiel A.

    2017-02-01

    We report a successful passive Q-switching of a Tm:YLF laser operating at λ = 1.9 μm, using a Co2+:AgCl0.5Br0.5 saturable absorber. Approximately 200-ns long, 150 μJ pulses were obtained. Increase in pump energy resulted in repetitive pulsing, with a repetition rate approximately proportional to the pump pulse energy. Room-temperature optical transmission saturation curves measured in ∼1-mm thick Co2+:AgCl0.5Br0.5 plates yielded a ground state absorption cross section σgs =(7.8 ± 0.5) ×10-18 cm2 , and an excited state absorption cross section σes =(3.3 ± 0.3) ×10-18 cm2 , at λ = 1.9 μm. The lifetime of the A2(4F) second excited-state of the octahedral O symmetry was τ∗ =(0.6 ± 0.06) ns .

  3. Passively synchronized Q-switched and mode-locked dual-band Tm3+:ZBLAN fiber lasers using a common graphene saturable absorber

    Science.gov (United States)

    Jia, Chenglai; Shastri, Bhavin J.; Abdukerim, Nurmemet; Rochette, Martin; Prucnal, Paul R.; Saad, Mohammed; Chen, Lawrence R.

    2016-11-01

    Dual-band fiber lasers are emerging as a promising technology to penetrate new industrial and medical applications from their dual-band properties, in addition to providing compactness and environmental robustness from the waveguide structure. Here, we demonstrate the use of a common graphene saturable absorber and a single gain medium (Tm3+:ZBLAN fiber) to implement (1) a dual-band fiber ring laser with synchronized Q-switched pulses at wavelengths of 1480 nm and 1840 nm, and (2) a dual-band fiber linear laser with synchronized mode-locked pulses at wavelengths of 1480 nm and 1845 nm. Q-switched operation at 1480 nm and 1840 nm is achieved with a synchronized repetition rate from 20 kHz to 40.5 kHz. For synchronous mode-locked operation, pulses with full-width at half maximum durations of 610 fs and 1.68 ps at wavelengths of 1480 nm and 1845 nm, respectively, are obtained at a repetition rate of 12.3 MHz. These dual-band pulsed sources with an ultra-broadband wavelength separation of ~360 nm will add new capabilities in applications including optical sensing, spectroscopy, and communications.

  4. Passively synchronized Q-switched and mode-locked dual-band Tm(3+):ZBLAN fiber lasers using a common graphene saturable absorber.

    Science.gov (United States)

    Jia, Chenglai; Shastri, Bhavin J; Abdukerim, Nurmemet; Rochette, Martin; Prucnal, Paul R; Saad, Mohammed; Chen, Lawrence R

    2016-11-02

    Dual-band fiber lasers are emerging as a promising technology to penetrate new industrial and medical applications from their dual-band properties, in addition to providing compactness and environmental robustness from the waveguide structure. Here, we demonstrate the use of a common graphene saturable absorber and a single gain medium (Tm(3+):ZBLAN fiber) to implement (1) a dual-band fiber ring laser with synchronized Q-switched pulses at wavelengths of 1480 nm and 1840 nm, and (2) a dual-band fiber linear laser with synchronized mode-locked pulses at wavelengths of 1480 nm and 1845 nm. Q-switched operation at 1480 nm and 1840 nm is achieved with a synchronized repetition rate from 20 kHz to 40.5 kHz. For synchronous mode-locked operation, pulses with full-width at half maximum durations of 610 fs and 1.68 ps at wavelengths of 1480 nm and 1845 nm, respectively, are obtained at a repetition rate of 12.3 MHz. These dual-band pulsed sources with an ultra-broadband wavelength separation of ~360 nm will add new capabilities in applications including optical sensing, spectroscopy, and communications.

  5. Laser-induced breakdown spectroscopy analysis of solids using a long-pulse (150 ns) Q-switched Nd:YAG laser.

    Science.gov (United States)

    Yamamoto, Karen Y; Cremers, David A; Foster, Leeann E; Davies, Mathew P; Harris, Ronny D

    2005-09-01

    Laser-induced breakdown spectroscopy (LIBS) measurements are typically carried out using pulses (50 mJ) from a flashlamp-pumped electro-optically Q-switched Nd:YAG laser (EO-laser) or excimer laser. Here we report LIBS analyses of solids using an acousto-optically Q-switched Nd:YAG laser (AO-laser) producing 150 ns pulses of lower energy (10 mJ) at repetition rates up to 6 kHz. The high repetition rate allows increased spatial or depth sampling over a given time period compared to the EO-laser. Results of AO-laser based LIBS analysis of (1) steels, (2) soils, and (3) surface stains and dusts are described. Detection limits for Cr, Cu, Mn, Ni, and Si in steel ranged from 0.11 to 0.24% using a commercial polychromator-based detection system with limits 4--30 times lower achieved using a laboratory-based detection system. The minimum detectable masses of Ba, Cr, Mn, and Sr on a metal surface were estimated with 1.2 pg/shot achieved for Sr. Detection limits for Ba and Sr in soil were 296 and 52 ppm, respectively. The temperatures, spectra, and emission decay curves from plasmas generated by the AO- and EO-lasers are compared and some characteristics of particles ablated by the AO-laser are described.

  6. Generation of microwave radiation by nonlinear interaction of a high-power, high-repetition rate, 1064-nm laser in KTP crystals

    CERN Document Server

    Borghesani, A F; Carugno, G

    2013-01-01

    We report measurements of microwave (RF) generation in the centimeter band accomplished by irradiating a nonlinear KTiOPO$_4$ (KTP) crystal with a home-made, infrared laser at $1064\\,$nm as a result of optical rectification (OR). The laser delivers pulse trains of duration up to $1\\,\\mu$s. Each train consists of several high-intensity pulses at an adjustable repetition rate of approximately $ 4.6\\,$GHz. The duration of the generated RF pulses is determined by that of the pulse trains. We have investigated both microwave- and second harmonic (SHG) generation as a function of the laser intensity and of the orientation of the laser polarization with respect to the crystallographic axes of KTP.

  7. PULSAR: A High-Repetition-Rate, High-Power, CE Phase-Locked Laser for the J.R. Macdonald Laboratory at Kansas State University

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Itzhak, Itzik (Itzhak) [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Carnes, Kevin D. [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Cocke, C. Lew [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Fehrenbach, Charles W. [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Kumarappan, Vinod [PULSAR: A High-Repetition-Rate, High-Power, CE Phase-Locked Laser for the J.R. Macdonald Laboratory at Kansas State University; Rudenko, Artem [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Trallero, Carlos [J.R. Macdonald Laboratory, Physics Department, Kansas State University

    2014-05-09

    This instrumentation grant funded the development and installation of a state-of-the-art laser system to be used for the DOE funded research at the J.R. Macdonald Laboratory at Kansas State University. Specifically, we purchased a laser based on the KMLABs Red-Dragon design, which has a high repetition rate of 10-20 kHz crucial for multi-parameter coincidence measurements conducted in our lab. This laser system is carrier-envelope phase (CEP) locked and provides pulses as short as 21 fs directly from the amplifier (see details below). In addition, we have developed a pulse compression setup that provides sub 5 fs pulses and a CEP tagging capability that allows for long measurements of CEP dependent processes.

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

    CSIR Research Space (South Africa)

    Esser, MJD

    2009-06-01

    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...

  9. 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.

    2003-01-01

    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 Y

  10. Treatment of nevus of Ota by the Q-switched alexandrite laser.

    Science.gov (United States)

    Alster, T S; Williams, C M

    1995-07-01

    The Q-switched alexandrite laser (755 nm, 100 nanoseconds) selectively targets and destroys cutaneous pigment such as that found in dermal pigmented lesions and tattoos. The nevus of Ota is a benign dermal melanocytic lesion, which, due to its large size and periocular location, has been notoriously difficult to treat. Utilizing the principles of selective photothermolysis, the alexandrite laser could effect an excellent treatment for nevus of Ota. To report the effectiveness of the Q-switched alexandrite laser in treating nevus of Ota. Seven patients with nevus of Ota were treated with the Q-switched alexandrite laser (755 nm, 100 nanoseconds) with energy densities ranging from 4.75 to 7.0 J/cm2 at 8-12-week intervals. Response to therapy was evaluated through independent observation and rating of sequential photographs by two blinded observers. Histologic examinations of lesional skin biopsies before and after completion of laser treatments were performed. An average of two laser treatments were required to effect an average clinical improvement of 50%. Five patients showed 100% lesional clearance after an average of five treatments. No scarring, textural changes, or pigmentary side effects were observed in treated skin. Histology of laser-irradiated lesions revealed elimination of upper dermal pigmentation without epidermal disruption, and rare melanophages and pigmented spindle cells in the deep reticular dermis. No lesional recurrences were observed up to 1 year following treatment. The Q-switched alexandrite laser can effectively eliminate nevus of Ota without untoward side effects, such as scarring.

  11. Investigation of passively synchronized dual-wavelength Q-switched lasers based on V:YAG saturable absorber

    DEFF Research Database (Denmark)

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

    2006-01-01

    In this paper the results of a theoretical and experimental investigation of synchronized passive Q-switching of two Nd:YVO4-based solid-state lasers operating at two different wavelengths, is described. A V:YAG saturable absorbing material was used as a passive Q-switch performing...

  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;

    2011-01-01

    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 al...

  13. Generation of Shear Alfvén Waves by Repetitive High Power Microwave Pulses Near the Electron Plasma Frequency - A laboratory study of a ``Virtual Antenna''

    Science.gov (United States)

    Wang, Yuhou; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Papadopoulos, Konstantinos

    2015-11-01

    ELF / ULF waves are important in terrestrial radio communications but difficult to launch using ground-based structures due to their enormous wavelengths. In spite of this generation of such waves by field-aligned ionospheric heating modulation was first demonstrated using the HAARP facility. In the future heaters near the equator will be constructed and laboratory experiments on cross-field wave propagation could be key to the program's success. Here we report a detailed laboratory study conducted on the Large Plasma Device (LaPD) at UCLA. In this experiment, ten rapid pulses of high power microwaves (250 kW X-band) near the plasma frequency were launched transverse to the background field, and were modulated at a variable fraction (0.1-1.0) of fci. Along with bulk electron heating and density modification, the microwave pulses generated a population of fast electrons. The field-aligned current carried by the fast electrons acted as an antenna that radiated shear Alfvén waves. It was demonstrated that a controllable arbitrary frequency (f

  14. Continuous-wave and Q-switched operation of a resonantly pumped Ho³⁺:KY₃F₁₀ laser.

    Science.gov (United States)

    Schellhorn, Martin; Parisi, Daniela; Eichhorn, Marc; Tonelli, Mauro

    2014-03-01

    We report continuous-wave and repetitively Q-switched operation of a resonantly pumped Ho3+:KY3F10 laser at room temperature. End pumped by a Tm3+-doped silica fiber laser operating at 1938 nm, a maximum laser power of 7.8 W was obtained at a wavelength of ∼2041  nm for 21 W of absorbed pump power, corresponding to a slope efficiency of 60.7% with respect to absorbed power. At a repetition rate of 10 kHz up to 0.78 mJ, energy per pulse was demonstrated with pulse widths of 100 ns. The beam propagation factor (M2) was measured to be <1.26 at the maximum output power.

  15. High-power LD side-pump Nd: YAG regenerative amplifier at 1 kHz repetition rate with volume Bragg gratings (VBG) for broadening and compressor

    Science.gov (United States)

    Long, Ming-Liang; Chen, Li-Yuan; Chen, Meng; Li, Gang

    2016-05-01

    Pulse width of 8.7 ps was broadened to 102.2, 198 ps with single and double pass the VBG respectively. When the 102.2 ps pulse was injected into 1 kHz repetition rate of LD side-pump Nd: YAG regenerative amplifier (RA), pulse width of 87.5 ps at 1 kHz was obtained with the pulse energy of 9.4 mJ, the beam quality of M^2 factor was 1.2. The pulse width was compressed to 32.7 ps with a single pass VBG and the pulse energy reduced to 8.8 mJ, and the power density was up to 15.2 GW/cm2, the stability for pulse to pulse rms is about 0.6 %, beam pointing was about 35 μrad. In addition, when 198 ps pulse was injected into RA, pulse width of 156 ps was obtained which energy was 9.6 mJ, the pulse width was compressed to 38 ps by double passing the VBG, the pulse energy decreased to 8.5 mJ. Chirped VBG is a new way to obtain high-intensity picosecond pulse laser system simple and smaller.

  16. 1064 nm Q switched Nd: YAG laser treatment of nevus of Ota: An Indian open label prospective study of 50 patients

    Directory of Open Access Journals (Sweden)

    Hemanta Kumar Kar

    2011-01-01

    Full Text Available Background: Nevus of Ota is very common in Asians. Estimated male to female ratio is 1:4.8. Patients seek treatment early in life due to psychological trauma and cosmetic disfigurement. The creation of high power, short pulse Q switched lasers has recently provided tools for considerable therapeutic advances in the treatment of dermal pigmented lesions. Aims: To determine the efficacy and side-effect profile of Q switched Nd:YAG Laser (QSNYL in fifty Indian patients. Methods: Fifty patients of nevus of Ota underwent multiple treatments (average 5 sessions at monthly intervals carried out over a period of 2 years with QSNYL (Med-lite C6. Of the 50 patients, 2 were males; and the rest were females. Skin types treated included phototype IV and V. The response after subsequent treatments was documented through serial photographs that were taken before and after every treatment session. Response to the treatment was graded based on quartile grading scale. Results: Near total improvement was seen in 8%, marked improvement in 22%, moderate improvement in 38% and 32% patients reported less than 25% clearing of the lesion. All patients reported some improvement. Transient postinflammatory hyperpigmentation was observed in 4 (8% patients, which cleared with use of sunscreens and bleaching agents within 2 months. No textural change or scarring was observed in any patient. Conclusions: QSNYL is an easy-to-perform and effective treatment in cases of nevus of Ota in Indian patients with few side effects.

  17. Intense Pulsed Light and Low-Fluence Q-Switched Nd:YAG Laser Treatment in Melasma Patients

    Science.gov (United States)

    Na, Se Young; Cho, Soyun

    2012-01-01

    Background Recently, low fluence collimated Q-switched (QS) Nd:YAG laser has drawn attention for the treatment of melasma. However, it needs a lot of treatment sessions for the substantial results and repetitive laser exposures may end up with unwanted depigmentation. Objective We evaluated the clinical effects and safety of the combinational treatment, using intense pulsed light (IPL) and low fluence QS Nd:YAG laser. Methods Retrospective case series of 20 female patients, with mixed type melasma, were analyzed using medical records. They were treated with IPL one time, and 4 times of weekly successive low fluence Nd:YAG laser treatments. At each visit, digital photographs were taken under the same condition. Melanin index (MI) and erythema index (EI) were measured on the highest point on the cheekbones. Modified melasma area and severity index (MASI) scores were calculated by two investigators using digital photographs. Results The mean values of MI and EI decreased significantly after treatments. The modified MASI score has decreased by 59.35%, on average. Sixty percents of the participants did not require any more treatments, and no clinical aggravations were observed during the follow-up period (mean 5.9 months). Conclusion IPL and low fluence laser may elicit a clinical resolution in the mixed type melasma with long term benefits. PMID:22879709

  18. Preparation of BiSrCaCuO Multilayers by Use of Slower Q-switched 266 nm YAG Laser

    Science.gov (United States)

    Kaneko, Satoru; Shimizu, Yoshitada; Ohya, Seishiro

    2001-08-01

    Multilayers of Bi2Sr2Ca1Cu2Ox{\\slash}Bi2Sr2Cu1Ox were prepared by pulsed laser deposition (PLD) using the fourth harmonic 266 nm YAG. Compared to an excimer laser, YAG PLD required the higher oxygen atmosphere. The higher oxygen pressure together with the lower energy generated by YAG laser collapsed the region of plume emission. In order to produce the same energy density as an excimer, only Q-switch was modulated by 2 Hz while the flash lamp kept the original repetition rate of 10 Hz. With the rate of 2 Hz, we obtained the higher energy density per pulse, and more stable laser output of the fourth harmonics, 266 nm. To characterize the multilayers, reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) were employed, and indicative of epitaxial layers with limited in-plane order. The resistivities of multilayers were measured by the Van der Pauw method, and showed the temperatures of superconducting transition, Tc0 (R=0), around 65 K on the multilayers.

  19. Recent advances in two-photon 3D laser lithography with self-Q-switched Nd:YAG microchip lasers

    Science.gov (United States)

    Baldeck, Patrice L.; Prabhakaran, Prem; Liu, Chao-Yuan; Bouriau, Michel; Gredy, Laetitia; Stephan, Olivier; Vergote, Thomas; Chaumeil, Hélène; Malval, Jean-Pierre; Lee, Yi-Hsiung; Lin, Chih-Lang; Lin, Chin-Te; Hsueh, Ya Hsun; Chung, Tien-Tung

    2013-09-01

    We review our recent results towards the development of a turnkey 3D laser printer, based on self-Q-switched microchip Nd:YAG lasers, with reproducible sub-100nm resolution, and with large-scale (cm) and fast-speed (cm/sec) capability at micron resolution. First of all, we report on line fabrication with 70nm lateral, and 150nm longitudinal resolutions without significant shrinking. This is due to the tight focusing with green visible wavelength, large numerical aperture, and excellent resin properties. Secondly, we report on two-photon sensitive photoacid generators that lead to efficient 3D microfabrication with epoxy SU-8 resin. Thirdly, we demonstrate high-speed microfabrication of large scale, millimeter size, scaffolds and cemtimeter height needle with high repetition rate (130Khz), and high average power (1W) amplified microchip laser. Finally we demonstrate the two-photon induced cross-linking of antibodies to determine the type of red blood cells in microfluidic channels.

  20. Passively Q-switched mid-infrared fluoride fiber laser around 3 µm using a tungsten disulfide (WS2) saturable absorber

    Science.gov (United States)

    Wei, Chen; Luo, Hongyu; Zhang, Han; Li, Chun; Xie, Jitao; Li, Jianfeng; Liu, Yong

    2016-10-01

    In this letter, we demonstrate a passively Q-switched Ho3+/Pr3+ co-doped fluoride fiber laser centered at 2865.7 nm using a tungsten disulfide (WS2) saturable absorber (SA) for the first time, to the best of our knowledge. A multilayer WS2 film was fabricated using the sulfidation grown method and then transferred onto an Au mirror to act as the cavity feedback and SA device in a linear cavity. Under a launched pump power of 318.5 mW, stable Q-switched pulses with an average output power of 48.4 mW were achieved with a pulse duration of 1.73 µs and repetition rate of 131.6 kHz, resulting in a pulse energy of 0.37 µJ. Our experimental results confirm that WS2 can be an effective nonlinear modulator that is suitable for pulse generation at the 3 µm waveband.

  1. The performance of a novel Ho:LuAG ceramic laser Q-switched by a polycrystalline Cr2+:ZnS saturable absorber

    Science.gov (United States)

    Zhang, Y.; Yao, B. Q.; Cui, Z.; Li, J.; Li, H.; Xie, T. F.; Li, C. Y.; Kou, H. M.; Pan, Y. B.

    2017-01-01

    A novel Ho:LuAG ceramic laser Q-switched by a polycrystalline Cr2+:ZnS saturable absorber was reported for the first time in this paper. We took a diode-pumped Tm:YLF laser emitting at 1.9075 μm as the pump source. The laser operated in both continuous wave mode and passively Q-switching (PQS) mode. The maximum PQS output power of 2.67 W was obtained with a slope efficiency of 26.4%. When the absorbed pump power increased from 4.78 to 10.8 W, with three output couplers of T = 2%, T = 10% and T = 25%, the pulse widths decreased as the pump power increased, from 102.9 to 89.2 ns, from 147.1 to 127.6 ns, and from 173 to 150 ns, respectively, and the repetition frequency varied from 10.2 to 20.1 kHz, from 9.3 to 18.3 kHz, and from 8.45 to 16.66 kHz as well. The central wavelength remained constant 2100.64 nm with the change of output couplers and operation modes. Furthermore, the output laser had a beam quality factor M 2 of 1.1.

  2. Linearly polarized, Q-switched, erbium-doped fiber laser incorporating a bulk-structured bismuth telluride/polyvinyl alcohol saturable absorber

    Science.gov (United States)

    Lee, Jinho; Lee, Junsu; Koo, Joonhoi; Chung, Hojai; Lee, Ju Han

    2016-07-01

    We experimentally demonstrate a linearly polarized, passively Q-switched, erbium (Er)-doped fiber laser using a saturable absorber (SA) based on a composite consisting of a bulk-structured bismuth telluride (Bi2Te3) topological insulator (TI) and polyvinyl alcohol (PVA). The SA was constructed on a polarization maintaining (PM) fiber ferrule platform, which had a sandwich structure. Its saturation intensity and modulation depth were measured to be ˜ and ˜4.1%, respectively. Using the prepared Bi2Te3/PVA SA in a PM Er-doped fiber ring laser, stable Q-switched pulses with a degree of polarization of ˜98.6% and an azimuth angle of ˜-0.34 deg were demonstrated. The minimum pulse width was measured to be ˜1.58 μs at a repetition rate of 47.1 kHz. This experimental demonstration verifies that a thin film based on a bulk-structured Bi2Te3 TI can fit into a sandwich-structured SA based on PM fiber ferrules.

  3. Modeling the pulse shape of Q-switched lasers to account for terminal-level relaxation

    Institute of Scientific and Technical Information of China (English)

    Zeng Qin-Yong; Wan Yong; Xiong Ji-Chuan; Zhu Da-Yong

    2011-01-01

    To account for the effect of lower-level relaxation, we have derived a characteristic equation for describing the laser pulse from the modified rate equations for Q-switched lasers. The pulse temporal profile is related to the ratio of the lower-level lifetime to the cavity lifetime and the number of times the population inversion density is above the threshold. By solving the coupled rate equations numerically, the effect of terminal-level lifetime on pulse temporal behaviour is analysed. The mode is applied to the case of a diode-pumped Nd:YAG laser that is passively Q-switched by a Cr4+:YAG absorber. Theoretical results show good agreement with the experiments.

  4. Laser-tissue interaction in tattoo removal by q-switched lasers.

    Science.gov (United States)

    Barua, Shyamanta

    2015-01-01

    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.

  5. Treatment of nevus of OTA by Q-switched, frequency doubled, ND: Yag laser

    Directory of Open Access Journals (Sweden)

    National Skin and Hair Care Centre

    2002-01-01

    Full Text Available Nevus of Ota is a dermal melanocytic nevus for which hitherto no effective therapy was available. Lasers have been successfully tried for ablation. But there is no Indian experience till date. Q- Switched, Frequency Doubled, Nd: YAG Laser was installed at our centre an year ago. The first operated case, which has shown near complete pigment dilution, is being presented. The patient underwent three treatments with a minimum of 2 months between sessions. Pre and post therapy photographs were taken and side effects documented. The patient has shown near complete pigment dilution after 3 treatments. Q-Switched, Frequency Doubled, Nd: YAG Laser is effective in treating Nevus of Ota in the Indian skin types. There are no complications noticed till date in our experience.

  6. Treatment of tattoos by Q-switched ruby laser. A dose-response study

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-07-01

    Tattoo treatment with Q-switched ruby laser pulses (694 nm, 40 to 80 nanoseconds) was studied by clinical assessment and light and electron microscopy. Fifty-seven blue-black tattoos or portions thereof (35 amateur and 22 professional) were irradiated with 1.5 to 8.0 J/cm2 at a mean interval of 3 weeks. Substantial lightening or total clearing occurred in 18 (78%) of 23 amateur tattoos and 3 (23%) of 13 professional tattoos in which the protocol was completed. Response was related to exposure dose. Scarring occurred in one case, and persistent confettilike hypopigmentation was frequent. Optimal fluence was 4 to 8 J/cm2. Clinicohistologic correlation was poor. Q-switched ruby laser pulses can provide an effective treatment for tattoos.

  7. Laser-tissue interaction in tattoo removal by Q-switched lasers

    Directory of Open Access Journals (Sweden)

    Shyamanta Barua

    2015-01-01

    Full Text Available 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.

  8. Dynamical modelling of measured time series from a Q-switched CO sub 2 laser

    CERN Document Server

    Horbelt, W; Bünner, M J; Meucci, R; Ciofini, M

    2003-01-01

    The transient dynamics of a Q-switched CO sub 2 laser is modelled quantitatively on the base of the four level model, a five dimensional nonlinear system of ordinary differential equations. Using the multiple shooting technique, internal parameters of the laser are estimated and the unobserved time courses of the population densities are constructed. For excitations barely above the laser threshold large pulse variations are identified as an effect of small variations of the pump parameter.

  9. Refractive Q-switching of a ruby laser by a moving plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, M.; John, P.K.

    1982-10-15

    A ruby laser was Q-switched by means of a plasma. The plasma, which had a density of up to 10/sup 18/ cm/sup -3/, was produced in an electromagnetic shock tube. The density gradient created by the reflected plasma was large enough to produce measurable refraction of the laser beam. The laser cavity, which was initially misaligned, attained perfect alignment when the plasma was introduced into the cavity.

  10. Finite-difference time-domain methods to analyze ytterbium-doped Q-switched fiber lasers.

    Science.gov (United States)

    Hattori, Haroldo T; Khaleque, Abdul

    2016-03-01

    Q-switched lasers are widely used in material processing, laser ranging, medicine, and nonlinear optics--in particular, Q-switched lasers in optical fibers are important since they cannot only generate high peak powers but can also concentrate high peak powers in small areas. In this paper, we present new finite-difference time-domain methods that analyze the dynamics of Q-switched fiber lasers, which are more flexible and robust than previous methods. We extend the method to analyze fiber ring lasers and compare the results with our experiments.

  11. Growth and passively self-Q-switched laser output of new Nd3+,Cr5+:GdVO4 crystal.

    Science.gov (United States)

    Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang; Yu, Yonggui; Gao, Wenlan; Tao, Xutang; Jiang, Minhua

    2008-03-03

    A new passively self-Q-switched Nd, Cr:GdVO(4) laser crystal was grown by Czochralski method for the first time to our knowledge. Polarized absorption spectra were measured at room temperature. The absorption bands display polarization character and an absorption band of Cr(5+) ions at 1110 nm enables the crystal to be a self-Q-switched laser material at 1.06 mum. In the passive self-Q-switching operation, the maximum output power, shortest pulse width, and largest pulse energy were obtained to be 265 mW, 230 ns, and 1.12 microJ, respectively.

  12. Comparison of the Q-switched alexandrite, Nd:YAG, and ruby lasers in treating blue-black tattoos.

    Science.gov (United States)

    Leuenberger, M L; Mulas, M W; Hata, T R; Goldman, M P; Fitzpatrick, R E; Grevelink, J M

    1999-01-01

    A new generation of highly selective short-pulsed lasers has emerged in recent years for the treatment of tattoos. Several studies (including reports by the present investigators) have proven the efficacy of each of the three commercially available, FDA approved devices; namely, the Q-switched alexandrite, Q-switched Nd:YAG and Q-switched ruby lasers. Considerable differences among the three have been reported in relation to the rate of clearing of the tattoo ink particles, tissue effects, beam profile, wound healing, and side effects. This study was primarily conducted to examine and compare the clinical response of patients with blue-black tattoos simultaneously treated with three different Q-switched lasers (alexandrite, Nd:YAG, ruby) with a focus on the percentage of tattoo lightening/clearance and the occurrence or non-occurrence of pigmentary change as a side effect. A total of forty-two blue-black tattoos seen at two laser centers (Massachusetts General Hospital Dermatology Laser Center and Laser and Skin Surgery Center of La Jolla) were simultaneously treated with three types of Q-switched lasers: a Candela Q-switched alexandrite laser (755nm 50-100 nanoseconds, 3.0 mm spot size, 6-8 J/cm2); a Continuum Biomedical Q-switched Nd:YAG laser (1064nm, 10-20 nanoseconds, 3.0 mm spot size, 5-10 J/cm2); and a Spectrum Q-switched ruby laser (694 nm, 25-40 nanoseconds, 5.0 mm spot size, 4-10 J/cm2). Paired t-tests and McNemar tests were used to compare the treatment outcome and pigmentation side effects between sites per tattoo, with each site representative of one of the three lasers. The statistical significance level was set at p tattoo lightening versus the Q-switched Nd:YAG and Q-switched alexandrite lasers. An increase in the number of treatments paralleled a statistically significant increase in tattoo clearance for all three Q-switched lasers. The Q-switched ruby laser had the highest clearance rate in blue-black tattoos and the highest incidence of long

  13. The removal of cutaneous pigmented lesions with the Q-switched ruby laser and the Q-switched neodymium: yttrium-aluminum-garnet laser. A comparative study.

    Science.gov (United States)

    Tse, Y; Levine, V J; McClain, S A; Ashinoff, R

    1994-12-01

    The Q-switched ruby laser (QSRL) (694 nm) has been used successfully in the removal of tattoos and a variety of cutaneous pigmented lesions. The frequency-doubled Q-switched neodymium:yttrium-aluminum-garnet laser (QSNd:YAG) (1064 and 532 nm) has also been shown to be effective in the treatment of tattoos, however, little has been published regarding the QSNd:YAG laser in the removal of cutaneous pigmented lesions. The purpose of this study is to compare the efficacy and side effect profile of the QSRL and the frequency-doubled QSNd:YAG lasers in the removal of cutaneous pigmented lesions, including lentigines, café-au-lait macules, nevus of Ota, nevus spilus, Becker's nevus, postinflammatory hyperpigmentation, and melasma. Twenty patients with pigmented lesions were treated with the QSRL and the frequency-doubled QSNd:YAG lasers. Clinical lightening of the lesion was assessed 1 month after a single treatment. Side effects and patient satisfaction were also evaluated. A minimum of 30% lightening was achieved in all patients after only one treatment with either the QSRL or the frequency-doubled QSNd:YAG laser. The QSRL seems to provide a slightly better treatment response than the QSNd:YAG laser. Neither laser caused scarring or textural change of the skin. Most patients found the QSRL to be more painful during treatment, but the QSNd:YAG laser caused more postoperative discomfort. Both the QSRL and the frequency-doubled QSND:YAG laser are safe and effective methods of treatment of epidermal and dermal pigmented lesions.

  14. Passively Q-switched flashlamp pumped Nd:YAG laser using liquid graphene oxide as saturable absorber

    Science.gov (United States)

    Adnan, N. N.; Bidin, N.; Taib, N. A. M.; Haris, H.; Fakaruddin, M.; Hashim, A. M.; Krishnan, G.; Harun, S. W.

    2016-06-01

    The performance of passively Q-switched Nd:YAG laser operating at 1060 nm is demonstrated using liquid graphene oxide (GO) composite solution as saturable absorber for the first time. The Q-switched Nd:YAG laser is pumped by a xenon flashlamp. The GO was prepared using the simplified Hummer's method and then mixed with polyethylene oxide to form a composite solution. The Q-switched pulsed laser operates at wavelength of 1064.5 nm with a threshold pump energy of 33.64 J. The maximum output Q-switched laser energy of 41.6 mJ achieved at the maximum pump energy of 81 J. The corresponding pulse width is 98.67 ns.

  15. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  16. Passive Q-Switching Modelocked Yb3+-Doped Fibre Laser with GaAs Absorber Grown at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    FENG Xiao-Ming; WANG Yong-Gang; ZHANG Zhi-Gang; WANG Yong-Gang; LIU Yuan-Yuan; LAN Yong-Sheng; LIN Tao; WANG Jun; WANG Xiao-Wei; FANG Gao-Zhan; MA Xiao-Yu

    2005-01-01

    @@ GaAs absorber was grown at low temperature (550℃) by metal organic chemical vapour deposition (MOCVD)and was used as an output coupler with which we realized Q-switching modelocked Yb3+-doped fibre laser. The shortest period of the envelope of the Q-switched modelocking is about 3μs. The modelocking threshold is 4.27 W and the highest average output pulse power is 290mW. The modelocking frequency is 12MHz.

  17. Intracavity optical parametric oscillator at 1.5-7-μm wavelength pumped by passive Q-switched Nd:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Mingwei Gao; Chunqing Gao; Kun Tang; Zhifeng Lin; Xiuyong Zhang

    2008-01-01

    A high-repetition-rate eye-safe optical parametric oscillator(OPO),using a non-critically phase-matched KTP crystal intracavity pumped by a passively Q-switched Nd:GdVO4/Cr4+:YAG laser,is experimentally demonstrated.The conversion efficiency for the average power is 7% from pump diode input to OPO signal output and the slope efficiency is up to 10.3%.With an incident pump power of 7.3 W.the compact intracavity OPO(IOPO)cavity,operating at 15 kHz,produces an average power of 0.57 W at 1570 nm with a pulse width as short as 6 ns.The peak power at 1570 nm is higher than 6.3 kW.

  18. Q-switched dual-wavelength fiber laser using a graphene oxide saturable absorber and singlemode-multimode-singlemode fiber structure

    Science.gov (United States)

    Ahmad, H.; Zulkifli, A. Z.; Yasin, M.; Thambiratnam, K.

    2016-10-01

    A Q-switched dual-wavelength fiber laser using a graphene oxide-based saturable absorber to generate the desired output pulses is proposed and demonstrated. The system utilizes a singlemode-multimode-singlemode fiber structure to control the net losses in the cavity so that only two dominant wavelengths are allowed to oscillate. The proposed system is capable of generating an output with a high repetition rate of 27.1 kHz and a narrow pulse width of 4.03 µs. The output pulses also have average output power and pulse energy of up to 0.5 mW and 18.5 nJ, respectively. The 1st harmonic obtained has a high signal-to-noise ratio of 33.2 dB, indicating a highly stable pulse output with minimum mode hopping.

  19. Efficient Compound-Cavity Eye-Safe KTP OPO at 1.57 μm Pumped by an Electro-Optic Q-Switched Nd: YAG Laser

    Institute of Scientific and Technical Information of China (English)

    ZHONG Kai; WANG Yu-Ye; XU De-Gang; GENG You-Fu; WANG Jing-Li; WANG Peng; YAO Jian-Quan

    2009-01-01

    An efficient high-energy eye-safe optical parametric oscillator (OPO) based on a type-Ⅱ non-critically phasematched KTP crystal is demonstrated.The KTP OPO is pumped by a quasi-cw diode side-pumped electrooptic Q-switched Nd:YAG laser in a compound-cavity configuration.The maximum output energy of the signal wavelength at 1.57 μm is 66.5 m J,corresponding to an electrical- to-optical conversion efficiency of 4.47% and an optical-to-optical conversion efficiency of 12.1%.The pulse width (FWHM) is about 3.6 ns with a peak power of 18.5 MW.The output energy is insensitive to repetition rate and demonstrates good stability.

  20. Q-switching of a Tm,Ho:KLu(WO4)2 microchip laser by a graphene-based saturable absorber

    Science.gov (United States)

    Serres, J. M.; Loiko, P.; Mateos, X.; Jambunathan, V.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.

    2016-02-01

    The first Ho microchip laser passively Q-switched using a graphene-based saturable absorber is demonstrated based on a Tm,Ho:KLu(WO4)2 crystal cut along the N g-axis. A maximum average output power of 74 mW is extracted from the diode-pumped laser at 2061 nm with a slope efficiency of 4%. Pulses as short as 200 ns with an energy of ~0.2 μJ are obtained at a repetition rate of 340 kHz. The energy transfer (ET), 3F4 (Tm3+) ↔ 5I7 (Ho3+) is studied, yielding ET parameters of P 28  =  1.69 and P 71  =  0.15  ×  10-22 cm3 μs-1, revealing the strong prevalence of direct ET.

  1. Second Harmonic Generation Using an All-Fiber Q-Switched Yb-Doped Fiber Laser and MgO:c-PPLN

    Directory of Open Access Journals (Sweden)

    Chang-qing Xu

    2008-10-01

    Full Text Available We have experimentally demonstrated an efficient all-fiber passively Q-switched Yb-doped fiber laser with Samarium doped fiber as a saturable absorber. Average output power of 3.4 W at a repetition rate of 250 kHz and a pulse width of 1.1 microseconds was obtained at a pump power of 9.0 W. By using this fiber laser system and an MgO-doped congruent periodically poled lithium niobate (MgO:c-PPLN, second harmonic generation (SHG output at 532 nm was achieved at room temperature. The conversion efficiency is around 4.2% which agrees well with the theoretical simulation.

  2. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers

    CERN Document Server

    Woodward, R I; Runcorn, T H; Hu, G; Torrisi, F; Kelleher, E J R; Hasan, T

    2015-01-01

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.

  3. Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm

    Science.gov (United States)

    Lin, H. Y.; Pan, X.; Huang, X. H.; Xiao, M.; Xu, Y. C.; Zhu, W. Z.

    2016-03-01

    We demonstrate the first Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm based on the Stokes shift of 816 cm-1. At the pump power of 4.7 W, the maximum output power of the Stokes line at 1168.6 nm is 270.5 mW, corresponding to an optical conversion efficiency of 5.8%. The pulse width, pulse repetition rate, pulse energy and peak power are 8.8 ns, 35.8 kHz, 7.6 μJ and 0.86 kW, respectively. At the pump of 5.0 W, the Stokes line at 1097.2 nm based on Raman shift of 259 cm-1 also appears.

  4. Gold nanobipyramids as a saturable absorber for passively Q-switched Yb-doped fiber laser operation at 1.06 µm

    Science.gov (United States)

    Zhang, Huanian; Li, Bowen; Liu, Jie

    2017-02-01

    In this letter, gold nanobipyramids (Au-NBPs) are prepared using a seed-mediated growth method. The longitudinal surface plasmon resonance (SPR) absorption peak of the Au-NBPs is located at 1068 nm by controlling the aspect of the materials. To verify the absorption properties of the Au-NBP saturable absorber (SA), a passively Q-switched Yb-doped fiber laser is demonstrated. The maximum average output power of 3.33 mW is obtained under a pumped power of 340 mW. The minimum pulse width is 2.6 µs at a pulse repetition rate of 66.3 kHz. The results prove that Au-NBP are a promising SA with the potential for important applications in the field of pulse lasers.

  5. High power 355 nm diode-pumped solid-state laser

    Science.gov (United States)

    Yu, Yang; Cheng, Chee Yuen; Peng, Xiaoyuan; Yong, Saw Soon

    2015-07-01

    This paper reported a high-power diode-pumped solid-state laser for material processing applications with a target of more than 60 ns pulse width at 355 nm. As known, long pulse width IR laser (around 70-100 ns) is difficult to get high conversion efficiency to UV since the peak power is more than 2 times lower than 20-30 ns laser. However, the unique long pulse width characteristic makes the laser an ideal tool for flexible PCB drilling with 30-50 μm holes and for cutting portable devices. Up to 52.2% IR to UV conversion efficiency was obtained by our novel intra-cavity harmonic generation cavity design. A 9.3W UV output at 30 kHz was demonstrated with compact intra-cavity sum frequency design. Special conduction cooling-designed LD side-pumped module provided 17.8 W fundamental IR output power with AOM q-switching. The UV output pulse width is 76 ns at 30 kHz and 140 ns at 70 kHz. The type I and type II phase matching LBOs were used for intra-cavity harmonic generations of 355 nm. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated. The experimental results are in agreement with the theoretical modelling. This system will also be useful for many material processing applications such as PCB cutting and wafer scribing.

  6. Passively Q-switched EDFL using Fe3O4-nanoparticle saturable absorber

    OpenAIRE

    Bai, Xuekun; Mou, Chengbo; Xu, Luxi; Huang, Sujuan; Wang, Tingyun; Pu, Shengli; Zeng, Xianglong

    2015-01-01

    We experimentally demonstrate a passively Q-switched erbium-doped fiber laser (EDFL) operation by using a saturable absorber based on Fe3O4 nanoparticles (FONP) in magnetic fluid (MF). As a kind of transition metal oxide, the FONP has a large nonlinear optical response with a fast response time for saturable absorber. By depositing MF at the end of optical fiber ferrule, we fabricated a FONP-based saturable absorber, which enables a strong light-matter interaction owing to the confined transm...

  7. Compact efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO4 crystal as a self-Raman medium.

    Science.gov (United States)

    Chang, Y T; Su, K W; Chang, H L; Chen, Y F

    2009-03-16

    We report on an efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO(4) crystal as a self-Raman gain medium. A diffusion-bonded crystal not only reduces the thermal effects but also increase the interaction length for the stimulated Raman scattering. With an input pump power of 17.2 W, average power of 2.23 W at the first- Stokes wavelength of 1525 nm is generated at a pulse repetition rate of 40 kHz, corresponding to a conversion efficiency of 13%.

  8. High brightness sub-nanosecond Q-switched laser using volume Bragg gratings

    Science.gov (United States)

    Anderson, Brian M.; Hale, Evan; Venus, George; Ott, Daniel; Divliansky, Ivan; Glebov, Leonid

    2016-03-01

    The design of Q-switched lasers capable of producing pulse widths of 100's of picoseconds necessitates the cavity length be shorter than a few centimeters. Increasing the amount of energy extracted per pulse requires increasing the mode area of the resonator that for the same cavity length causes exciting higher order transverse modes and decreasing the brightness of the output radiation. To suppress the higher order modes of these multimode resonators while maintaining the compact cavity requires the use of intra-cavity angular filters. A novel Q-switched laser design is presented using transmitting Bragg gratings (TBGs) as angular filters to suppress the higher order transverse modes. The laser consists of a 5 mm thick slab of Nd:YAG, a 3 mm thick slab of Cr:YAG with a 20% transmission, one TBG aligned to suppress the higher order modes along the x-axis, and a 40% output coupler. The gratings are recorded in photo-thermo-refractive (PTR) glass, which has a high damage threshold that can withstand both the high peak powers and high average powers present within the resonator. Using a 4.1 mrad TBG in a 10.8 mm long resonator with an 800μm x 400 μm pump beam, a nearly diffraction limited beam quality of M2 = 1.3 is obtained in a 0.76 mJ pulse with a pulse width of 614 ps.

  9. Treatment of infraorbital dark circles using 694-nm fractional Q-switched ruby laser.

    Science.gov (United States)

    Xu, Tian-Hua; Li, Yuan-Hong; Chen, John Z S; Gao, Xing-Hua; Chen, Hong-Duo

    2016-12-01

    The objective of this study was to evaluate the efficacy and safety of using a 694-nm fractional Q-switched ruby laser to treat infraorbital dark circles. Thirty women with infraorbital dark circles (predominant color: dark/brown) participated in this open-labeled study. The participants received eight sessions of 694-nm fractional Q-switched ruby laser treatment using a fluence of 3.0-3.5 J/cm(2), at an interval of 7 days. The melanin deposition in the lesional skin was observed in vivo using reflectance confocal microscopy (RCM). The morphological changes were evaluated using a global evaluation, an overall self-assessment, and a Mexameter. Twenty-eight of the 30 patients showed global improvements that they rated as excellent or good. Twenty-six patients rated their overall satisfaction as excellent or good. The melanin index indicated a substantial decrease from 240.44 (baseline) to 194.56 (P dark/brown infraorbital dark circles is caused by increased melanin deposition in the upper dermis. The treatment of these infraorbital dark circles using a 694-nm fractional QSR laser is safe and effective.

  10. Black phosphorus as a new broadband saturable absorber for infrared passively Q-switched fiber lasers

    CERN Document Server

    Jiang, Tian; Zheng, Xin; Yu, Hao; Cheng, Xiang-Ai

    2015-01-01

    Black phosphorus (BP) with its enticing electric and optical properties is intensely researched in the field of optoelectronics. In this paper, Q-switched pulses at 1550 nm and 2 um wavelengths are obtained by inserting bulk-structured BP based saturable absorber (SA) into an erbium-doped fiber laser (EDFL) and an thulium/holmium-doped fiber laser (THDFL), respectively. The BP-SA was prepared by depositing powered BP material on to the flat side of a side-polished single mode fiber. Q-switched 1550 nm pulses with width tuned from 9.35 to 31 us were obtained for the EDFL. For the THDFL, over 100 nm wavelength range could be achieved from 1832 to 1935 nm by adjusting the pump power. To the best of our knowledge, these results demonstrated the broadband saturable absorption property of BP and for the first time verified that BP as a new two-dimensional material for applications in saturable absorption devices.

  11. Compact MEMS mirror based Q-switch module for pulse-on-demand laser range finders

    Science.gov (United States)

    Milanović, Veljko; Kasturi, Abhishek; Atwood, Bryan; Su, Yu; Limkrailassiri, Kevin; Nettleton, John E.; Goldberg, Lew; Cole, Brian J.; Hough, Nathaniel

    2015-02-01

    A highly compact and low power consuming Q-switch module was developed based on a fast single-axis MEMS mirror, for use in eye-safe battery-powered laser range finders The module's 1.6mm x 1.6mm mirror has cost than the traditional Electro-Optical Q-Switch. Because pulse-on-demand capability is required, resonant mirrors cannot be used to achieve the needed performance. Instead, a fast point-to-point analog single-axis tilt actuator was designed with a custom-coated high reflectance (HR) mirror to withstand the high intra-cavity laser fluence levels. The mirror is bonded on top of the MEMS actuator in final assembly. A compact MEMS controller was further implemented with the capability of autonomous on-demand operation based on user-provided digital trigger. The controller is designed to receive an external 3V power supply and a digital trigger and it consumes ~90mW during the short switching cycle and ~10mW in standby mode. Module prototypes were tested in a laser cavity and demonstrated high quality laser pulses with duration of ~20ns and energy of over 3mJ.

  12. Q-switch techniques of CO2 laser%CO2激光调Q技术

    Institute of Scientific and Technical Information of China (English)

    徐艳; 谢冀江; 李殿军; 杨贵龙; 陈飞

    2014-01-01

    Short-pulse CO2 laser has significant applications in many fields such as laser ranging , environmen-tal detection , space communication and laser interaction with matter .Q-switch techniques are important ap-proach for generating short-pulse CO2 laser and have been extensively studied by researchers .Main Q-switch techniques for CO2 laser are reviewed in this paper , including mechanical Q-switch, electro-optically Q-switch, acousto-optically Q-switch, passively Q-switch and double Q-switch.The key technical points and problems of each Q-switch technique are summarized and analyzed .In addition, the tendencies of Q-switch techniques for CO 2 laser are proposed .%调Q技术是实现小型CO2激光器短脉冲输出的重要手段,近年来随着短脉冲CO2激光器在激光测距、测速、成像雷达、环境探测、空间通讯及激光与物质相互作用等领域应用需求的不断增长,激光调Q技术越来越受到国内外专家的关注而成为红外激光技术的研究热点之一。本文就目前用于CO2激光器中实现短脉冲输出的5种主要调Q技术(机械调Q技术、电光调Q技术、声光调Q技术、被动调Q技术、复合调Q技术)的国内外发展历程和现状进行了综合评述,总结分析了各种方法的关键技术和存在的问题,并简要分析了该技术的未来发展趋势。

  13. 声光调Q CO2激光器的输出特性%Output performance of acousto-optic Q-switched CO2 laser

    Institute of Scientific and Technical Information of China (English)

    潘其坤; 谢冀江; 阮鹏; 张来明; 张传胜

    2012-01-01

    采用谐振腔内插入声光调制器(AOM)的方法获得了小型CO2激光器的高重频、窄脉宽、高峰值功率输出。通过分析CO2激光器声光调Q的工作原理,利用基于小信号增益和饱和光强的耦合输出数学模型给出了激光器最佳输出镜透过率的数值解,并运用相关实验装置对该数学模型进行了实验验证。理论分析和实验结果均表明:该声光调Q CO2激光器的最佳输出镜透过率为39%。研究了激光器输出性能随脉冲重复频率的变化规律,当脉冲重复频率〉1 kHz时,激光器输出峰值功率下降,这与CO2分子上能级寿命有关,并受声光调Q开关热效应的影响。实验中获得的激光器脉冲频率在1 Hz~100 kHz可调。在脉冲频率为1 kHz时,获得的激光脉冲宽度为156 ns,脉冲峰值功率为10 kW,且稳定性较好,非常适合于作激光与物质相互作用的光源。%A compact CO2 laser with short pulse duration,high peak power and high repetition was developed by using an Acousto-optic(AO) Q-switch.The operating principle of the AO Q-switch was analyzed,and the theoretical model of CO2 laser was introduced based on the small-signal gain and saturation intensity.Then the optimal numerical solution of the transmission for an output mirror was given by this model.Based on the compact CO2 laser in our laboratory,the experiments to verify the theoretical result were performed.The optimal coupling output factor gained by the theory and experiments is 39%.The variable law of laser output performance with pulse repetition frequency was researched.Results show that the peak power of the laser will fall down when the pulse repetition frequency is greater than 1 kHz,which is related to the radiation life of CO2 molecular upper energy level,and is limited by the heat effect of AO Q-switch.The range of pulse repetition frequency can be adjusted from 1 Hz to 100 kHz.When the pulse repetition frequency is 1 kHz,the measured pulse

  14. Tunable graphene Q-switched erbium-doped fiber laser with suppressed self-mode locking effect.

    Science.gov (United States)

    Zhou, Da-Peng; Wei, Li; Liu, Wing-Ki

    2012-05-10

    Self-mode locking effect in a wideband tunable graphene-based passively Q-switched erbium-doped fiber laser has been observed experimentally. Q-switching is achieved by using graphene as a saturable absorber, while a tunable bandpass filter with a narrow bandwidth is used to obtain wideband tunability. We propose to suppress the modulation on each pulse from self-mode locking by introducing three subring resonators constructed with three 3 dB couplers into the laser ring cavity. Moreover, the laser output characteristics with respect to pump power are studied in detail. A stable Q-switched erbium-doped fiber laser with a tunable range from 1522 nm to 1568 nm is demonstrated experimentally.

  15. Ytterbium-doped Q-switched fiber laser based upon manganese dioxide (MnOsub>2sub>) saturable absorber.

    Science.gov (United States)

    Hattori, Haroldo T; Khaleque, Abdul; Liu, Liming; Greck, Michael R

    2016-11-10

    Manganese dioxide (MnOsub>2sub>) is an abundant material that is widely used in many devices, such as alkaline batteries. At infrared frequencies, MnOsub>2sub> is lossy and strongly absorbs light. These characteristics make MnOsub>2sub> a potential candidate as a low-cost saturable absorber in Q-switched lasers. In this paper, we examine the performance of MnOsub>2sub> as a saturable absorber in an ytterbium-doped Q-switched fiber laser: we show that it can produce pulses with durations ranging from 300 to 1800 ns.

  16. Diode-side-pumped, passively Q-switched Yb:LuAG laser

    Science.gov (United States)

    Kaskow, Mateusz; Galecki, Lukasz; Jabczynski, Jan K.; Skorczakowski, Marek; Zendzian, Waldemar; Sulc, Jan; Nemec, Michal; Jelinkova, Helena

    2015-10-01

    A high-gain, diode-side-pumped Yb:LuAG slab laser was designed and investigated for use at room temperature. Pumping occurred from a fast-axis collimated 2D laser diode stack emitting at a wavelength of 970 nm, with 0.8 J over a duration of 0.8 ms. The pump scheme, which enabled efficient mode matching and high gain, was analysed and experimentally verified for different dopant levels. An energy of 100 mJ with 23% slope efficiency in a near fundamental mode was achieved in the free-running regime. A peak power of 2.5 MW and a pulse energy of 10.1 mJ were demonstrated in passive Q-switching by means of a Cr:YAG saturable absorber with 39% initial transmission. The study defined the indications for optimizing such a system.

  17. Effect of Q-switched Laser Surface Texturing of Titanium on Osteoblast Cell Response

    Science.gov (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.

  18. Wavelength Spacing Tunable, Multiwavelength Q-switched Fiber Laser Mode-locked by Graphene Oxide

    CERN Document Server

    Gao, Lei

    2014-01-01

    We demonstrate a wavelength spacing tunable, multiwavelength Q-switched mode-locked fiber laser (QML) based on a fiber taper deposited with graphene oxide. The operation of the laser can be understood in terms of the formation of bunches of QMLs which possess small temporal intervals, and multiwavelength spectra are generated due to the Fourier transformation. We find that the temporal spacing of the QMLs is highly sensitive to the pump power, and as a result, the wavelength spacing can be easily tuned by varying the pump power. Our experimental laser provides a wavelength spacing tuning range from ~0.001 nm to 0.145 nm with a pump power variation less than 10 mW. The laser could be developed into a low lost wavelength spacing tunable optical source for a wide range of applications, such as spectroscopy, microwave/terahertz signal generation, optical metrology, optical communications and sensing.

  19. Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser

    Energy Technology Data Exchange (ETDEWEB)

    Bihari, Bipin; Biruduganti, Munidhar; Gupta, Sreenath

    2015-04-01

    A robust end pumped, passively Q-switched, air-cooled, microlaser was designed and prototyped to yield a 1064 nm pulsed laser output of 21 mJ/P with a pulse width of 4.2 ns FWHM. This microlaser was coupled to a standard laser plug carrying a sapphire lens with 13 mm back focal length. This assembly was tested in a natural gas fueled single-cylinder engine, and in one cylinder of a turbocharged 6-cylinder engine. Single cylinder engine tests showed extension of the lean ignition limit which enabled an efficiency improvement of 0.2% while meeting emission regulations. The tests conducted in the 6-cylinder engine showed highly improved ignition stability.

  20. Response of nevus of Ota to Q-switched alexandrite laser according to treatment interval

    Institute of Scientific and Technical Information of China (English)

    Zhong Lu(卢忠); Junpang Chen(陈军庞); Xiasheng Wang(王侠生); Lihua Fang(方丽华); Sheng Jiao(焦圣); Wen Huang(黄雯)

    2003-01-01

    In order to determine the appropriate treatment interval, 267 patients who underwent 3 sessions oftreatment with Q-switched alexandrite laser were divided into 4 groups according to treatment interval,and their clinical responses were compared. Among them, 187 were asked about the process of pigmentfading. Moreover, light and transmission electron microscopy were performed. It was noted that theclinical response of the 5 - 6 month interval group was significantly better than that of the 3 - 4 monthgroup, but showed no significant difference from that of the 7 - 8 or ≥ 9 month group. 80.21% ofinvestigated patients stated that marked pigment fading could no longer be observed 7 months afterirradiation. 4 months after irradiation, the degenerated melanosomes and cell debris were still scatteredamong collagen fibers, scavenged gradually by macrophage. In conclusion, an appropriate treatmentinterval is 5 - 6 months.

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

    CSIR Research Space (South Africa)

    Botha, RC

    2015-02-01

    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..., Krugersdorp, 1740 South Africa 2Stellenbosch University, P/Bag X1, Matieland, 7602 South Africa 3National Laser Centre, CSIR, PO Box 395, Pretoria, 0001 South Africa 4Formerly at CSIR, now at Heriot-Watt University, EH14 4AS Edinburgh, UK 5Formerly at CSIR...

  2. Experimental investigation on CFRP milling by low power Q-switched Yb:YAG laser source

    Science.gov (United States)

    Genna, S.; Tagliaferri, F.; Papa, I.; Leone, C.; Palumbo, B.

    2016-05-01

    In the present study, laser milling of CFRP plate by means of a 30W Q-Switched Yb:YAG fiber laser is investigated through statistical analysis. Milling tests were performed at the nominal power changing the pulse power; the scanning speed, the hatch distance and the released energy. Design of Experiments (DoE) and ANalysis Of VAriance (ANOVA) were applied with the aim to improve the process performances in term of material removal rate and heat affected zone extension. The results show that, the adopted laser is an effective solution for the CFRP milling. Moreover, adopting an accurate approach to the problem, process variability and material damages can be easily reduced.

  3. Q-switched laser removal of tattoos: a clinical and spectroscopic investigation of the mechanism

    Science.gov (United States)

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

    1996-01-01

    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.

  4. Tattoo removal by Q-switched yttrium aluminium garnet laser: client satisfaction.

    Science.gov (United States)

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

    2017-05-01

    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.

  5. Q-switched erbium-doped fiber ring laser with piezoelectric transducer-based PS-CFBG

    Science.gov (United States)

    Wu, Liangying; Pei, Li; Wang, Jianshuai; Li, Jing; Ning, Tigang; Liu, Shuo

    2016-09-01

    In this letter, a Q-switched erbium-doped fiber ring laser (EDFRL) with piezoelectric transducer (PZT)-based phase shift chirped fiber Bragg grating (PS-CFBG) has been proposed and demonstrated first. As known, the phase shift can be induced and wiped periodically by applying a modulation signal on the PZT. This makes it possible for the PZT-based PS-CFBG to be used in Q-switched EDFRL. To verify the performance of this Q-switched EDFRL system, some theoretical analyses and experiments have been performed. It is found that, when the PZT is modulated by a signal with frequencies of 1 and 2 kHz, pulse widths of the Q-switched pulse train are 19.8 μs and 15.6 μs, respectively. Besides, the corresponding pulse energies are 1.16 μJ (1 kHz) and 1.91 μJ (2 kHz) with a pump power of 90 mW.

  6. Treatment of nasal ala nodular congenital melanocytic naevus with carbon dioxide laser and Q-switched Nd:YAG laser.

    Science.gov (United States)

    Zeng, Ying; Ji, Chenyang; Zhan, Kui; Weng, Weili

    2016-11-01

    Total excision of congenital melanocytic nevi (CMN) is not always feasible. We here present our experience of using carbon dioxide laser and Q-switched neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser to treat nodular CMN of the nasal ala. Q-switched Nd:YAG laser and/or carbon dioxide laser were used to treat eight cases of nasal ala nodular CMN. Carbon dioxide laser was utilized to ablate all visible melanocytic tissue within one session. Ablation was performed so as to reproduce the original anatomical contours as closely as possible. Recurrences were treated in the same way. Q-switched Nd:YAG laser was also used to irradiate all target lesions to achieve the desired end point within one session. The intervals between treatments were at least 8 weeks. Recurrence of melanocytic tissue, scar formation, pigmentation, depigmentation, and the degree of patient satisfaction were recorded at every visit. Two of the eight patients were treated with Q-switched Nd:YAG laser. Although, the lesion lightened in one of them, the hyperplastic tissue persisted. Eventually, these two patients, along with the remaining six patients, were successfully treated with a carbon dioxide laser. We recommend carbon dioxide laser treatment for nodular nasal CMN. This simple treatment does not involve skin flap transplantation and has good cosmetic outcomes. Although Q-switched Nd:YAG laser does lighten some nasal nodular CMNs, it does not eradicate the hyperplastic tissue, and is therefore not an effective treatment for nodular nasal CMN.

  7. Treatment of pigmentary disorders in patients with skin of color with a novel 755 nm picosecond, Q-switched ruby, and Q-switched Nd:YAG nanosecond lasers: A retrospective photographic review.

    Science.gov (United States)

    Levin, Melissa Kanchanapoomi; Ng, Elise; Bae, Yoon-Soo Cindy; Brauer, Jeremy A; Geronemus, Roy G

    2016-02-01

    Laser procedures in skin of color (SOC) patients are challenging due to the increased risk of dyspigmentation and scarring. A novel 755 nm alexandrite picosecond laser has demonstrated effectiveness for tattoo removal and treatment of acne scars. No studies to date have evaluated its applications in pigmentary disorders. The purpose of this retrospective study was to evaluate the safety profile and efficacy of the picosecond alexandrite laser compared to the current standard treatment, Q-switched ruby and neodynium (Nd):YAG nanosecond lasers, for pigmentary disorders in SOC patients. A retrospective photographic and chart evaluation of seventy 755 nm alexandrite picosecond, ninety-two Q-switched frequency doubled 532 nm and 1,064 nm Nd:YAG nanosecond, and forty-seven Q-switched 694 nm ruby nanosecond laser treatments, in forty-two subjects of Fitzpatrick skin types III-VI was conducted in a single laser specialty center. The picosecond laser was a research prototype device. Treatment efficacy was assessed by two blinded physician evaluators, using a visual analog scale for percentage of pigmentary clearance in standard photographs. Subject assessment of efficacy, satisfaction, and adverse events was performed using a questionnaire survey. The most common pigmentary disorder treated was Nevus of Ota (38.1%), followed by solar lentigines (23.8%). Other pigmentary disorders included post-inflammatory hyperpigmentation, congenital nevus, café au lait macule, dermal melanocytosis, Nevus of Ito, and Becker's nevus. Clinical efficacy of the Q-switched nanosecond lasers and picosecond laser treatments were comparable for lesions treated on the face with a mean visual analog score of 2.57 and 2.44, respectively, corresponding to approximately 50% pigmentary clearance. Subject questionnaires were completed in 58.8% of the picosecond subjects and 52.0% of the Q-switched subjects. Eighty four percent of subjects receiving Q-switched nanosecond laser treatments and 50% of the

  8. Gene expression profiling of melanocytes following Q-Switched Ruby laser irradiation.

    Science.gov (United States)

    Hafner, Christian; Stempfl, Thomas; Bäumler, Wolfgang; Hohenleutner, Ulrich; Landthaler, Michael; Vogt, Thomas

    2008-01-01

    The Q-switched Ruby laser (QSRL) is used for the treatment of pigmented lesions. The influence of QSRL treatment on gene expression of nontransformed primary melanocytes has not been addressed in vitro. We investigated the gene expression profile of melanocytes following QSRL irradiation. Primary melanocytes were irradiated with the QSRL (694 nm). Early and late transcriptional effects were analyzed using the Affymetrix gene array platform. Laser irradiation of melanocytes had minor effects on mRNA expression. We found only 31 out of 14,500 genes which were at least twofold up- or downregulated. The differential expression of heme oxygenase 1 and galanin in QSRL-treated melanocytes was additionally confirmed by real-time RT-PCR. Analysis of a selection of 36 genes which are known to be associated with malignant melanoma development and progression revealed no significantly aberrant expression in the QSRL-treated melanocytes. Our study shows that QSRL treatment of primary melanocytes in vitro does not cause major alterations of global gene expression and particularly of genes associated with malignant melanoma. However, since QSRL treatment may have different effects on gene expression of melanocytic cells in vivo, further studies are required to evaluate QSRL treatment of (nevo-) melanocytic lesions. (c) 2008 S. Karger AG, Basel.

  9. Water content contribution in calculus phantom ablation during Q-switched Tm:YAG laser lithotripsy.

    Science.gov (United States)

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

    2015-01-01

    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.

  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: Wangyanlin0@126.com, E-mail: chuyunh@163.com, E-mail: yyuch@soho.com, E-mail: zouxiaol@126.com [Physics school, Hubei University of Technology, Wuhan, China 430068 (China)

    2011-01-01

    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. Multiparameter bifurcations and mixed-mode oscillations in Q-switched CO2 lasers.

    Science.gov (United States)

    Doedel, Eusebius J; Pando L, Carlos L

    2014-05-01

    We study the origin of mixed-mode oscillations and related bifurcations in a fully molecular laser model that describes CO2 monomode lasers with a slow saturable absorber. Our study indicates that the presence of isolas of periodic mixed-mode oscillations, as the pump parameter and the cavity-frequency detuning change, is inherent to Q-switched CO2 monomode lasers. We compare this model, known as the dual four-level model, to the more conventional 3:2 model and to a CO2 laser model for fast saturable absorbers. In these models, we find similarities as well as qualitative differences, such as the different nature of the homoclinic tangency to a relevant unstable periodic orbit, where the Gavrilov-Shilnikov theory and its extensions may hold. We also show that there are isolas of periodic mixed-mode oscillations in a model for CO2 lasers with modulated losses, as the pump parameter varies. The coarse-grained bifurcation diagrams of the periodic mixed-mode oscillations in these models suggest that these oscillations belong to similar classes.

  12. Accidental bilateral Q-switched neodymium laser exposure: treatment and recovery of visual function

    Science.gov (United States)

    Zwick, Harry; Stuck, Bruce E.; Dunlap, Weldon; Scales, David K.; Lund, David J.; Ness, James W.

    1998-05-01

    A 21 year old female was accidentally exposed in both eyes when she looked into the 10 cm exit aperture of a military laser designator emitting 1064 nm q-switched (30 ns) pulses at a 10 pulse per second rate. Steroid therapy (methylprednisolone sodium succinate) was initiated within 6 hours post exposure. Initial ophthalmoscopic observation revealed small contained macular hemorrhages in each eye. Fluorescein angiography (FA) showed minimal leakage. Visual acuity was 20/100 and 20/60 in OD and OS respectively. Contrast sensitivity in both eyes was depressed across all spatial frequencies by more than 1.5 log units. At four weeks post exposure, no significant macular scarring was apparent and visual acuity returned to 20/25 in both eyes. Contrast sensitivity had improved to normal levels with a peak at 3 cycles/degree. At one year post exposure, visual acuity was 20/13 in both eyes and measures of contrast sensitivity were within normal limits. During the course of recovery, the patient's fixation shifted from a slightly superior temporal site back to the central foveal region. The foveal lesion sites were still evident by ophthalmoscopy and Amsler grid measurements but were deemed functional when the patient placed small targets generated by the scanning laser ophthalmoscope in the lesion site for discrimination. This outcome indicates remarkable recovery of visual function and suggests that early administration of steroids may assist in preserving the natural neural recovery process of the photoreceptor matrix by minimizing intraretinal scar formation.

  13. 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))

    1991-07-01

    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.

  14. Single-walled carbon nanotubes oust graphene and semiconductor saturable absorbers in Q-switched solid-state lasers at 2 µm

    Science.gov (United States)

    Mateos, Xavier; Loiko, Pavel; Choi, Sun Young; Rotermund, Fabian; Aguiló, Magdalena; Díaz, Francesc; Griebner, Uwe; Petrov, Valentin

    2017-09-01

    The superior performance of a saturable absorber (SA) based on randomly-oriented single-walled carbon nanotubes (SWCNTs) operating in the spectral region of their first fundamental transition E 11 over a graphene-SA containing several (n  =  3) carbon layers and a commercial semiconductor SA (SESA) for passive Q-switching of bulk thulium solid-state lasers is demonstrated. Using SWCNT-SA in a compact diode-pumped Tm:KLuW laser, a maximum average output power of 1.36 W is achieved at 1932-1944 nm corresponding to a slope efficiency of 41% and pulse characteristics of 48 ns/5.5 µJ which are superior to that for graphene-SA (123 ns/3.1 µJ) and SESA (61 ns/1.1 µJ). SWCNT-SAs are promising for eye-safe miniature lasers at ~2 µm generating nanosecond pulses in the MHz repetition frequency range.

  15. Passively Q-switched thulium-doped fiber laser with silver-nanoparticle film as the saturable absorber for operation at 2.0 µm

    Science.gov (United States)

    Ahmad, H.; Samion, M. Z.; Muhamad, A.; Sharbirin, A. S.; Ismail, M. F.

    2016-12-01

    In this work, a compact thulium-doped fiber laser with a Q-switched output is proposed and demonstrated. A thulium-doped fiber is used for the laser, with a peak absorption of 200 dB m-1 at 790 nm and a cutoff wavelength of 1350 nm as the primary gain medium, and a silver-based saturable absorber as the pulse generation mechanism. The pulses obtained from the proposed laser have repetition rates from 38.3 kHz up to 56.2 kHz, with a pulse width as low as 4.2 µs and pulse energy as high as 67.3 nJ at a maximum pump power of 228.8 mW. The generated pulses are highly stable, showing no changes or fluctuations over operation for a period of 60 min, and further validated with signal-to-noise ratios of 57.0 dB and 59.5 dB in the optical and frequency domains respectively. The proposed laser has high potential for eye-safe applications in manufacturing and medicine.

  16. Passively Q-switched laser with single longitudinal mode based on the frequency selection of grating and F-P etalon in twisted-mode folded cavity

    Institute of Scientific and Technical Information of China (English)

    Bao'an Song; Weijiang Zhao; Deming Ren; Yanchen Qu; Heyong Zhang; Liming Qian; Xiaoyong Hu

    2009-01-01

    A passively Q-switched side-pumped laser with folded resonator is specially constructed for singlelongitudinal-mode smooth pulse output.Nd:YAG is chosen as the laser active medium and Cr4+:YAG as the saturable absorber medium.Additionally,the method of frequency selection by grating with 1200 line/mm and Fabry-Perot(F-P)etalon is used in the twisted-mode cavity.The single-frequency smooth pulses are produced with 10-Hz repetition rate,20-ns pulse width,and 1.064-μm wavelength.The probability of single-frequency laser output measured is over 99% by using the methods of Fourier analysis and F-P etalon multiple-beam interferometry at the threshold voltage.The measured near-field and far-field angles of divergence axe 1.442 and 1.315 mrad,respectively.The values of M2 are 1.32 and 1.31 separately with the knife-edge method.Single pulse at 1.064 μm with the energy of 8.8 mJ is achieved in TEM00 mode.

  17. Laser ablation of borosilicate glass with high power shaped UV nanosecond laser pulses

    Science.gov (United States)

    von Witzendorff, Philipp; Bordin, Andrea; Suttmann, Oliver; Patel, Rajesh S.; Bovatsek, James; Overmeyer, Ludger

    2016-03-01

    The application of thin borosilicate glass as interposer material requires methods for separation and drilling of this material. Laser processing with short and ultra-short laser pulses have proven to enable high quality cuts by either direct ablation or internal glass modification and cleavage. A recently developed high power UV nanosecond laser source allows for pulse shaping of individual laser pulses. Thus, the pulse duration, pulse bursts and the repetition rate can be set individually at a maximum output power of up to 60 W. This opens a completely new process window, which could not be entered with conventional Q-switched pulsed laser sources. In this study, the novel pulsed UV laser system was used to study the laser ablation process on 400 μm thin borosilicate glass at different pulse durations ranging from 2 - 10 ns and a pulse burst with two 10 ns laser pulses with a separation of 10 ns. Single line scan experiments were performed to correlate the process parameters and the laser pulse shape with the ablation depth and cutting edge chipping. Increasing the pulse duration within the single pulse experiments from 2 ns to longer pulse durations led to a moderate increase in ablation depth and a significant increase in chipping. The highest material removal was achieved with the 2x10 ns pulse burst. Experimental data also suggest that chipping could be reduced, while maintaining a high ablation depth by selecting an adequate pulse overlap. We also demonstrate that real-time combination of different pulse patterns during drilling a thin borosilicate glass produced holes with low overall chipping at a high throughput rate.

  18. Scaling output energy in a diode-end-pumped passively Q-switched laser with a flat-flat resonator

    Science.gov (United States)

    Tang, C. Y.; Huang, Y. J.; Liang, H. C.; Chen, Y. F.; Su, K. W.

    2017-01-01

    The spatial and temporal behaviors in a diode-end-pumped passively Q-switched laser with a flat-flat resonator are systematically explored as a function of the cavity length. A Nd:YAG/Cr4+:YAG miniature laser is experimentally used to show that the scale-up of the pulse energy without the higher-order transverse modes can be practically realized by optimizing the cavity length as a function of the pump size. A theoretical analysis is performed to confirm the experimental results. The extracavity second harmonic generation is experimentally conducted to demonstrate the usefulness of the laser design. PACS number(s): 42.60.Gd Q-switching; 42.55.Xi Diode-pumped lasers; 42.55.-f Lasers; 42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatiotemporal dynamics.

  19. Dual-wavelength synchronously Q-switched solid-state laser with multi-layered graphene as saturable absorber.

    Science.gov (United States)

    Zhao, Yongguang; Li, Xianlei; Xu, Miaomiao; Yu, Haohai; Wu, Yongzhong; Wang, Zhengping; Hao, Xiaopeng; Xu, Xinguang

    2013-02-11

    Using multilayered graphene as the saturable absorber (SA), Nd:LYSO crystal as the laser material, we demonstrated a laser-diode (LD) pumped, dual-wavelength passively Q-switched solid-state laser. The maximum average output power is 1.8 W, the largest pulse energy and highest peak power is 11.3 μJ, 118 W, respectively. As we have known, they are the best results for passively Q-switched operation of graphene. The pulse laser is strong enough to realize extra-cavity frequency conversions. With a KTP crystal as the sum-frequency generator, the dual wavelengths are proved to be well time overlapped, which manifests the synchronous modulation to the dual-wavelength with multi-layered graphene.

  20. Treatment of gunpowder traumatic tattoo by Q-switched Nd:YAG laser: an unusual adverse effect.

    Science.gov (United States)

    Fusade, T; Toubel, G; Grognard, C; Mazer, J M

    2000-11-01

    The Q-switched Nd:YAG laser can completely eliminate traumatic tattoos. We report the results of the unsuccessful removal of traumatic tattoos among three patients with dermal inclusions of gunpowder who were shot at close range. Treatment was tried in each patient with a Q-switched Nd:YAG laser at a medium fluence (4-6 J/cm2). During treatment of our patients, each pulse provoked sparks and the immediate formation of bleeding trans- epidermal pits. After the healing process was completed, we observed poxlike scars and the spreading of pigments in the skin around the initial points of the tattoo. We hypothesize that the rapid transfer of high-energy pulses to powder particles creates microexplosions of these fragments resulting in cavitation and provoking transepidermal holes and subsequent scars. This adverse effect was only produced if the tattoo resulted from gun powder being shot at a short distance from the skin.

  1. Laboratory model for the study and treatment of traumatic tattoos with the Q-switched ruby laser

    Science.gov (United States)

    Silverman, Richard T.; Lach, Elliot

    1994-09-01

    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.

  2. CONTROL OF LASER RADIATION PARAMETERS: Passive laser Q switches made of glass doped with oxidised nanoparticles of copper selenide

    Science.gov (United States)

    Yumashev, K. V.

    2000-01-01

    Passive Q switching of Nd3+:YAG (λ = 1060 nm) and YAlO3:Nd3+ (1340 nm) lasers, as well as of an Er3+ (1540 nm) glass laser was realised by using glass doped with oxidised nanoparticles of copper selenide. Nonlinear optical properties of the nanoparticles (radius of 25 nm) in a glass matrix were studied by the picosecond absorption spectroscopy technique.

  3. Self-Mode-Locking in a Diode-Pumped Self-Q-Switched Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    杨林; 冯宝华; 张治国; Volker Gaebler; 刘百宁; Hans J. Eichler; 张世文

    2002-01-01

    We report for the first time on the observation of self-mode-locking in a diode pumped self-Q-switched (SQS)Nd3+,Cr4+ : YA G laser. This phenomenon results from significant excited state absorption of the Cr4+ ions in theco-doped host during the SQS laser pulses. The self-mode-locking occurs already slightly above the SQS laserthreshold. Experiments using relatively low saturable intensity achieved a modulation depth of more than 40%.

  4. Melanin index in assessing the treatment efficacy of 1064 nm Q switched Nd-Yag laser in nevus of Ota

    Directory of Open Access Journals (Sweden)

    Gomathy Sethuraman

    2013-01-01

    Full Text Available Background: Q-switched neodymium-yttrium aluminium-garnet (Q switched Nd-Yag laser has been used in the treatment of nevus of Ota in all skin types with variable success rate. Data with an objective assessment parameter to this laser treatment is lacking. Objective: To evaluate the utility of melanin index in assessing the treatment response and also determine the efficacy and safety of the Q-switched Nd-Yag laser (1064-nm in the treatment of nevus of Ota in Fitzpatrick skin types IV and V. Materials and Methods: A total of 35 patients treated with Nd-Yag laser were studied. The objective improvement (pigment clearance was determined by melanin index from two fixed points: A1, 2 cm below the pupil at the mid pupillary line (when the gaze is fixed; A2, the most prominent part of zygoma. The melanin index in these two areas was recorded as M1 and M2, respectively. The subjective clinical improvement was determined by the physician and the patient global assessment score. Results: The mean baseline melanin indices M1 and M2 were 59.54 ± 9.72 and 59.02 ± 9.16, respectively. At the last visit the mean M1 and M2 decreased to 53.8 ± 8.55 (P 50% pigment clearance. Conclusion: The melanin index, a simple non-invasive parameter is useful in assessing the treatment response more objectively. The 1064-nm Q-switched Nd-Yag laser offers good improvement in patients with nevus of Ota in darker skin types IV/V.

  5. Melanin Index in Assessing the Treatment Efficacy of 1064 nm Q Switched Nd-Yag Laser in Nevus of Ota

    Science.gov (United States)

    Sethuraman, Gomathy; Sharma, Vinod K; Sreenivas, Vishnubhatla

    2013-01-01

    Background: Q-switched neodymium-yttrium aluminium-garnet (Q switched Nd-Yag) laser has been used in the treatment of nevus of Ota in all skin types with variable success rate. Data with an objective assessment parameter to this laser treatment is lacking. Objective: To evaluate the utility of melanin index in assessing the treatment response and also determine the efficacy and safety of the Q-switched Nd-Yag laser (1064-nm) in the treatment of nevus of Ota in Fitzpatrick skin types IV and V. Materials and Methods: A total of 35 patients treated with Nd-Yag laser were studied. The objective improvement (pigment clearance) was determined by melanin index from two fixed points: A1, 2 cm below the pupil at the mid pupillary line (when the gaze is fixed); A2, the most prominent part of zygoma. The melanin index in these two areas was recorded as M1 and M2, respectively. The subjective clinical improvement was determined by the physician and the patient global assessment score. Results: The mean baseline melanin indices M1 and M2 were 59.54 ± 9.72 and 59.02 ± 9.16, respectively. At the last visit the mean M1 and M2 decreased to 53.8 ± 8.55 (P 50% pigment clearance. Conclusion: The melanin index, a simple non-invasive parameter is useful in assessing the treatment response more objectively. The 1064-nm Q-switched Nd-Yag laser offers good improvement in patients with nevus of Ota in darker skin types IV/V. PMID:24470713

  6. Gold nanorods saturable absorber for Q-switched Nd:GAGG lasers at 1 μm

    Science.gov (United States)

    Feng, Chao; Liu, Mingyi; Li, Yanbin; Gao, Xuejian; Kang, Zhe; Qin, Guanshi; Jia, Zhitai; Tao, Xutang; Song, Teng; Dun, Yangyang; Bai, Fen; Li, Ping; Wang, Qingpu; Fang, Jiaxiong

    2017-03-01

    A gold nanorod saturable absorber has been synthesized by the seed-mediated growth method characterized in detail. The absorption peak wavelength was 1080 nm, and the modulation depth was measured to be 9%. The performance of its Q-switched Nd:GAGG lasers at 1061 and 1106 nm has been systematically investigated, respectively. The corresponding shortest pulsewidths were 250 and 480 ns. Our experiment results proved that the GNR-SA is a promising saturable absorber for nanosecond bulk lasers.

  7. Passively Q-switched ytterbium-doped ScBO3 laser with black phosphorus saturable absorber

    Science.gov (United States)

    Lu, Dazhi; Pan, Zhongben; Zhang, Rui; Xu, Tianxiang; Yang, Ruilong; Yang, Bingchao; Liu, Zhongyuan; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-08-01

    We demonstrate a passively Q-switched Yb3+-doped ScBO3 bulk laser using a black phosphorous (BP) saturable absorber, a two-dimensional semiconductor. The response spectra of BP show that it is suitable as a universal switcher in the spectral range from the visible to midinfrared band. Considering the saturable absorption properties of BP and emission properties of Yb3+-doped crystals, the passively Q-switched bulk laser pulses were realized with the Yb3+:ScBO3 crystal as a gain material and a fabricated BP sample as a Q-switcher. Because of the large energy storage capacity of Yb3+:ScBO3, the maximum output energy is obtained to be 1.4 μJ, which is comparable with the previous reported maximum energy of graphene Q-switched lasers. The obtained results identify the potential capability of BP as a pulse modulator in bulk lasers, and BP plays an increasingly important role in a wide range of its applications, including photonics and optoelectronics.

  8. Mechanically deposited tungsten disulfide saturable absorber for low-threshold Q-switched erbium-doped fiber laser

    Science.gov (United States)

    Lau, K. Y.; Latif, A. A.; Abu Bakar, M. H.; Muhammad, F. D.; Omar, M. F.; Mahdi, M. A.

    2017-08-01

    In this paper, we report a Q-switched erbium-doped fiber laser incorporating tungsten disulfide (WS2) as the saturable absorber. A direct mechanical deposition technique using a scotch tape is employed to place the WS2 powder onto the tip of a fiber ferrule. Several runs of mechanical extraction are performed to reduce the thickness of WS2 powder on the fiber tip. The fabricated WS2 saturable absorber exhibits a saturation intensity of 548.6 MW/cm2, modulation depth of 4.1% and non-saturable loss of 67.8%. A ring cavity erbium-doped fiber laser integrating the WS2 saturable absorber yields continuous wave lasing and Q-switching threshold at pump power of 10 and 12.7 mW, respectively. This Q-switching pump power threshold is the lowest to the best of the authors' knowledge. The proposed technique of direct mechanical deposition is inexpensive, significantly faster and simpler compared to previously reported methods.

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

    Directory of Open Access Journals (Sweden)

    Shivangi Sharma

    2011-01-01

    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.

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

    Science.gov (United States)

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

    2014-06-02

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

  11. Diode array pumped, non-linear mirror Q-switched and mode-locked Nd : YVO4 laser – a good tool for powder SHG measurement

    Indian Academy of Sciences (India)

    P K Datta; Chandrajit Basu; S Mukhopadhyay; S K Das; G K Samanta; Antonio Agnesi

    2004-11-01

    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 operating in QML regime is much higher but pulses suffers from poor amplitude stability. The incorporation of an acousto-optic modulator as an active Q-switch enhances the stability of the QML pulse envelope. The second-order non-linearity of powdered crystalline urea is conclusively measured with respect to KDP while the laser is operating in passively Q-switched and passively mode-locked regime as well as in actively Q-switched and passively mode-locked regime.

  12. Simultaneous Q-switching and Frequency-doubling by a Single KTP Crystal in a Diode-pumped Nd: YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; HUO Yujing; HE Shufang; FENG Lichun

    2000-01-01

    The interrelation between the phase matching condition for second harmonic generation (SHG) and the electro-optic Q-switching in KTP was numerically analyzed. A diode-pumped Q-switched Nd: YVO4/KTP green laser was reported, where the KTP crystal was simultaneously used as both an electrooptic Q-switcher and a frequency-doubling crystal in type Ⅱ phase matching.Compared with the conventional frequency-doubling and Q-switching configuration, low loss and high efficiency characteristics were realized by using a single KTP crystal. The Q-switched green laser pulse with a peak power of 762 W and a pulse width of 12 ns was obtained with 1 W pump power.

  13. A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for controllable high-order Hermite-Gaussian modes

    Science.gov (United States)

    Dong, Jun; He, Yu; Bai, Sheng-Chuang; Ueda, Ken-ichi; Kaminskii, Alexander A.

    2016-09-01

    A nanosecond, high peak power, passively Q-switched laser for controllable Hermite-Gaussian (HG) modes has been achieved by manipulating the saturated inversion population inside the gain medium. The stable HG modes are generated in a Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser by applying a tilted pump beam. The asymmetrical saturated inversion population distribution inside the Nd:YVO4 crystal for desirable HG modes is manipulated by choosing the proper pump beam diameter and varying pump power. A HG9,8 mode passively Q-switched Nd:YVO4 microchip laser with average output power of 265 mW has been obtained. Laser pulses with a pulse width of 7.3 ns and peak power of over 1.7 kW working at 21 kHz have been generated in the passively Q-switched Nd:YVO4 microchip laser.

  14. Quasi-flat-top frequency-doubled Nd:glass laser for pumping of high-power Ti:sapphire amplifiers at a 0.1 Hz repetition rate.

    Science.gov (United States)

    Yanovsky, Victor; Kalinchenko, Galina; Rousseau, Pascal; Chvykov, Vladimir; Mourou, Gerard; Krushelnick, Karl

    2008-04-20

    A Nd:glass laser based on a novel design delivers up to 120 J energy pulses with a quasi-flat-top spatial profile at a 0.1 Hz repetition rate. The laser output is frequency-doubled with 50% efficiency and used to pump Ti:sapphire amplifiers. The developed design is perspective for use in the currently contemplated next step in ultra-high-intensity laser development.

  15. Mid-infrared ZGP optical parametric oscillator directly pumped by a lamp-pumped, Q-switched Cr,Tm,Ho:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Ab F.; Lee, Chris J.; Slot, van der Peter J.M.; Gross, Petra; Boller, Klaus-Jochen; Powers, Peter E.

    2007-01-01

    We generate mid-infrared pulsed light tunable between 5.6 μm and 6.6 μm using an optical parametric oscillator (OPO) directly pumped by a Cr,Tm,Ho:YAG, Q -switched laser operating at 2.1 μm. The Holmium laser uses a RTP Q -switch to produce pulses shorter than 100 ns and energies of up to 42 mJ in a

  16. Mid-Infrared ZGP optical parametric oscillator directly pumped by a lamp-pumped, Q-switched Cr,Tm,Ho:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; van der Slot, Petrus J.M.; Gross, P.; Boller, Klaus J.; Powers, Peter E.

    2007-01-01

    We generate mid-infrared pulsed light tunable between 5.6 μm and 6.6 μm using an optical parametric oscillator (OPO) directly pumped by a Cr,Tm,Ho:YAG, Q -switched laser operating at 2.1 μm. The Holmium laser uses a RTP Q -switch to produce pulses shorter than 100 ns and energies of up to 42 mJ in a

  17. High slope efficiency and low threshold in a laser-diode-pumped passively Q-switched ion-implanted Nd:YVO4 planar waveguide laser with GaAs saturable absorber

    Science.gov (United States)

    Du, G. L.; Li, G. Q.; Zhao, S. Z.; Li, T.; Yang, K. J.; Li, X.

    2011-11-01

    A passively Q-switched waveguide laser, to our knowledge, has been firstly demonstrated in Nd: YVO4 crystal formed by 3 MeV Si+ ion implantation at a dose of 1 × 1015 ions/cm2 at room temperature, in which GaAs was used as saturable absorber. The dependences of the average output power, pulse width, pulse repetition rate on absorbed pump power have been measured at different output plane mirror transmissions. At an absorbed pump power of 78.8 mW and output transmission of 20%, the shortest pulse width of 3.88 ns was obtained, corresponding to the peak power and single pulse energy of 212 W and 0.82 μJ, respectively. The threshold pump power was as low as 40 mW, and the slope efficiency was about 64.5% when the absorbed pump power was lower than 70 mW.

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

    Directory of Open Access Journals (Sweden)

    Nisar MS

    2013-05-01

    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. High power fiber lasers

    Institute of Scientific and Technical Information of China (English)

    LOU Qi-hong; ZHOU Jun

    2007-01-01

    In this review article, the development of the double cladding optical fiber for high power fiber lasers is reviewed. The main technology for high power fiber lasers, including laser diode beam shaping, fiber laser pumping techniques, and amplification systems, are discussed in de-tail. 1050 W CW output and 133 W pulsed output are ob-tained in Shanghai Institute of Optics and Fine Mechanics, China. Finally, the applications of fiber lasers in industry are also reviewed.

  20. Comparison of clinical efficacy and complications between Q-switched alexandrite laser and Q-switched Nd:YAG laser on nevus of Ota: a systematic review and meta-analysis.

    Science.gov (United States)

    Yu, Panxi; Yu, Nanze; Diao, Wenqi; Yang, Xiaonan; Feng, Yongqiang; Qi, Zuoliang

    2016-04-01

    Although the application of Q-switched lasers on nevus of Ota (OTA) is well demonstrated, debates about clinical option between Q-switched alexandrite laser (QSA) and Q-switched Nd:YAG laser (QSNY) still remain. This systematic review and meta-analysis estimated the overall successful rate of OTA pigment clearance and complication rate of QSA and QSNY and evaluated which laser could produce a better result. English articles evaluating pigment clearance and complications of QSA and/or QSNY on OTA were screened through predetermined inclusion and exclusion criteria and analyzed. The successful rate of pigment clearance and complication rate of QSA and QSNY were respectively calculated using a random-effects or fixed-effects model, depending on the heterogeneity of the included studies. The successful rate and complication rate of QSA and QSNY were compared statistically. Of the 140 articles searched, 13 met inclusion criteria. Totally, 2153 OTA patients treated by QSA and 316 patients treated by QSNY were analyzed. In QSA and QSNY groups, respectively, the successful rate of OTA pigment clearance was 48.3% (95% confidence interval (CI) 19.9-76.8%) and 41% (95% CI 9.7-72.2%), while the complication rate was 8.0% (95% CI 3.9-12.2%) and 13.4% (95% CI 7.7-19.0%). When compared with QSNY, QSA had a significantly higher successful rate (P = 0.017), and a lower complication rate (P = 0.000). According to this review, QSA may surpass QSNY in treatment for OTA as it had a superior successful rate of pigment clearance and a lower complication rate than QSNY did.

  1. HIGH REPETITION RATE MICROCHIP ER3+,YB3+:YAL3(BO34 DIODE-PUMPED LASER

    Directory of Open Access Journals (Sweden)

    K. N. Gorbachenya

    2012-01-01

    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.

  2. Spatially-temporal dynamics of a passively Q-switched Raman-active solid-state oscillator

    CERN Document Server

    Kalashnikov, V L; Yumashev, K V

    2009-01-01

    The spatially-temporal model of an all-solid-state passively Q-switched oscillator with an active medium providing the stimulated Raman scattering is presented. The model does not presume a Gaussian shape of the cylindrically symmetric modes at both fundamental and Stokes wavelengths. It is found, that the highly-nontrivial spatially-temporal dynamics can be regularized by the optimal choice of the oscillator parameters, viz. initial transmission of a saturable absorber, curvature of a spherical mirror, and output mirror transmission at the fundamental and Stokes wavelengths. As a result, the pulse can be substantially temporally squeezed and spatially broadened at both fundamental and Stokes wavelengths.

  3. Compact, Passively Q-Switched Nd:YAG Laser for the MESSENGER Mission to the Planet Mercury

    Science.gov (United States)

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

    2004-01-01

    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.

  4. Passive Q-switching of diode-pumped Yb:YAG microchip laser with ion-implanted GaAs

    Institute of Scientific and Technical Information of China (English)

    Yonggang Wang(王勇刚); Xiaoyu Ma(马骁宇); Bin Zhong(钟斌); Desong Wang(王德松); Qiulin Zhang(张秋琳); Baohua Feng(冯宝华)

    2004-01-01

    We reported a passive Q-switched diode laser pumped Yb:YAG microchip laser with an ion-implanted semiinsulating GaAs wafer. The wafer was implanted with 400-kev As+ in the concentration of 1016 ions/cm2.To decrease the non-saturable loss, we annealed the ion-implanted GaAs at 500 ℃ for 5 minutes and coated both sides of the ion-implanted GaAs with antireflection (AR) and high reflection (HR) films,respectively. Using GaAs wafer as an absorber and an output coupler, we obtained 52-ns pulse duration of single pulse.

  5. Infrared multiphoton dissociation of octafluorocyclobutane with a two-frequency Q-switched CO/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Pochon, E.; Weston, R.E. Jr.; Flynn, G.W.

    1985-01-03

    The infrared multiphoton dissociation of octafluorocyclobutane has been investigated by the use of two CO/sub 2/ laser pulses of different frequency, synchronized by the same Q-switching mirror. The dissociation yield has been determined as a function of laser pulse energy, frequency of the dissociating pulse, substrate pressure, and interpulse delay. Accompanying transport phenomena (expansion and diffusion) were taken into account by the use of appropriate models. The kinetic behavior of highly vibrationally excited c-C/sub 4/F/sub 8/ molecules indicates that collisional relaxation occurs at nearly gas kinetic rates. 47 references, 10 figures.

  6. Theoretical Analysis on the Simultaneous Operation of a Color-Center Laser and a Q-Switched Nd: YAG Laser

    Institute of Scientific and Technical Information of China (English)

    WU Xing; DING Yongkui; ZHANG Rui

    2000-01-01

    The simultaneous operation for the Q- switched Nd: YAG laser at 1.06 and the tunable color-center laser over 1.12~1.26 μm has been realized by using a LiF: F2- color-center crystal both as the Q-switcher for the Nd:YAG laser and as the active medium for the color-center laser. The interaction of the two lasers has been analyzed and calculated with the rate equations. The pulse duration of YAG laser is compressed, in agreement with the experimental results.

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

    CSIR Research Space (South Africa)

    Barnier, V

    2006-04-01

    Full Text Available . Interface Anal. 2006; 38: 406–409 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/sia.2181 XPS and SIMS study of aluminium native oxide modifications induced by Q-switched Nd : YAG laser treatment V. Barnier,1∗ O.../cm2. The grey curves represent optimum fits using the MRI model. Copyright  2006 John Wiley & Sons, Ltd. Surf. Interface Anal. 2006; 38: 406–409 DOI: 10.1002/sia 408 V. Barnier et al. (determined with MRI fit) with the laser fluence used (Table 1...

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

    OpenAIRE

    Tianxian Feng; Dong Mao; Xiaoqi Cui; Mingkun Li; Kun Song; Biqiang Jiang; Hua Lu; Wangmin Quan

    2016-01-01

    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...

  9. High power microwaves

    CERN Document Server

    Benford, James; Schamiloglu, Edl

    2016-01-01

    Following in the footsteps of its popular predecessors, High Power Microwaves, Third Edition continues to provide a wide-angle, integrated view of the field of high power microwaves (HPMs). This third edition includes significant updates in every chapter as well as a new chapter on beamless systems that covers nonlinear transmission lines. Written by an experimentalist, a theorist, and an applied theorist, respectively, the book offers complementary perspectives on different source types. The authors address: * How HPM relates historically and technically to the conventional microwave field * The possible applications for HPM and the key criteria that HPM devices have to meet in order to be applied * How high power sources work, including their performance capabilities and limitations * The broad fundamental issues to be addressed in the future for a wide variety of source types The book is accessible to several audiences. Researchers currently in the field can widen their understanding of HPM. Present or pot...

  10. High-power, narrow-band, high-repetition-rate, 5.9 eV coherent light source using passive optical cavity for laser-based angle-resolved photoelectron spectroscopy.

    Science.gov (United States)

    Omachi, J; Yoshioka, K; Kuwata-Gonokami, M

    2012-10-08

    We demonstrate a scheme for efficient generation of a 5.9 eV coherent light source with an average power of 23 mW, 0.34 meV linewidth, and 73 MHz repetition rate from a Ti: sapphire picosecond mode-locked laser with an output power of 1 W. Second-harmonic light is generated in a passive optical cavity by a BiB(3)O(6) crystal with a conversion efficiency as high as 67%. By focusing the second-harmonic light transmitted from the cavity into a β-BaB(2)O(4) crystal, we obtain fourth-harmonic light at 5.9 eV. This light source offers stable operation for at least a week. We discuss the suitability of the laser light source for high-resolution angle-resolved photoelectron spectroscopy by comparing it with other sources (synchrotron radiation facilities and gas discharge lamp).

  11. Comparison of Q-switched Nd: YAG laser and fractional carbon dioxide laser for the treatment of solar lentigines in Asians.

    Science.gov (United States)

    Vachiramon, Vasanop; Panmanee, Wikanda; Techapichetvanich, Thanya; Chanprapaph, Kumutnart

    2016-04-01

    Solar lentigines are benign pigmented lesions that occur mostly on sun-exposed areas. Q-switched and ablative lasers are effective for removing these lesions but the high incidence of postinflammatory hyperpigmentation raises concern in darker skin types. The objective of this study is to compare the efficacy and degree of postinflammatory hyperpigmentation with the Q-switched Nd:YAG and fractional carbon dioxide (CO2 ) laser for treatment of solar lentigines in Asians. Twenty-five Thai patients (skin phototype III-IV) with at least two lesions of solar lentigines on upper extremities were enrolled in this study. Two lesions were randomly selected for the treatment with a single session of Q-switched Nd:YAG or fractional CO2 laser. Outcomes were evaluated using physician grading scale, colorimeter, and patient self-assessment at 6 and 12 weeks after treatment. Side effects were recorded. A total of 532 nm Q-switched Nd:YAG laser showed significant improvement of pigmentation over fractional CO2 laser at 6th and 12th week by both colorimeter assessment and physician grading scale (P lasers was observed. In terms of patient self-assessment, 80% of the patients treated with 532 nm Q-switched Nd:YAG laser had excellent results compared to 8% in fractional CO2 laser group. However, fractional CO2 laser treatment had faster healing time and less pain score compared to Q-switched Nd:YAG laser. Q-switched Nd:YAG is superior to fractional CO2 laser for treatment of solar lentigines but requires longer healing time and produces more pain. The incidence of postinflammatory hyperpigmentation was not significantly different with both lasers. Further studies are needed to obtain the proper parameter and the treatment frequency of fractional CO2 laser in solar lentigines. © 2016 Wiley Periodicals, Inc.

  12. LD-pumped passively Q-switched red laser at 660 nm

    Institute of Scientific and Technical Information of China (English)

    Qinghua Xue(薛庆华); Quan Zheng(郑权); Yikun Bu(卜轶坤); Longsheng Qian(钱龙生)

    2004-01-01

    A laser diode (LD) pumped Nd:YAG red pulse laser at 660 nm was presented by V:YAG passively Qswitching and LBO intracavity frequency doubling. With 1.6-W incident pump power, average output power of 46-mW, pulse duration (FWHM) of 23.3 ns, pulse repetition rate of 21.6 kHz, peak power of 91.4 W, and single pulse energy of 2.13μJ were obtained. The beam quality factor M2 was less than 1.2. The fluctuations of pulse energy and repetition rate were less than 3% in 4 hours. The pulsed laser at 660 nm is expected to be used as the pump source of Cr3+:doped crystal to obtain the gain-switched tunable laser.

  13. High Power Cryogenic Targets

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Smith

    2011-08-01

    The development of high power cryogenic targets for use in parity violating electron scattering has been a crucial ingredient in the success of those experiments. As we chase the precision frontier, the demands and requirements for these targets have grown accordingly. We discuss the state of the art, and describe recent developments and strategies in the design of the next generation of these targets.

  14. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.

    1989-02-06

    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  15. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Science.gov (United States)

    Zysset, B.; LaGasse, M. J.; Fujimoto, J. G.; Kafka, J. D.

    1989-02-01

    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  16. Effect of cavity length on low-energy single longitudinal mode pre-lase Q-switched laser

    Science.gov (United States)

    Qing-Song, Li; Yuan, Dong; Yu, Liu; Xi-He, Zhang; Yong-Ji, Yu; Guang-Yong, Jin

    2017-09-01

    In this paper, the effect of cavity length on a low-energy single longitudinal mode (SLM) pre-lase Q-switched laser is analyzed and demonstrated. Taking a Pr:YLF laser as an example, the basic output characteristics under pre-lase technology are shown. The SLM is degraded when the cavity length is as large as 25 mm. Further, for cavity lengths of 15 or 20 mm, SLM is achieved with different output characteristics. Compared with a long cavity (20 mm), the short-cavity case (15 mm) is indeed helpful for obtaining an SLM laser; however, the single-pulse energy, pulse width, and energy extraction efficiency are decreased by 4.7, 48, and 6.7%, respectively. The results of this analysis show that the cavity length influences the output characteristics and determines the realization of SLM in a pre-lase Q-switched laser. This is because the short cavity induces a relatively strong gain identification for the seed signal. Then, the time cost of the mode competition decreases and SLM can be achieved easily. However, a long cavity is conducive to mode competition, which generates superior output characteristics.

  17. Hollow fiber optics with improved durability for high-peak-power pulses of Q-switched Nd:YAG lasers.

    Science.gov (United States)

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

    2007-03-10

    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.

  18. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser

    Directory of Open Access Journals (Sweden)

    Goldman A

    2014-08-01

    Full Text Available Alberto Goldman,1 Uwe Wollina2 1Clinica Goldman, Porto Alegre RS, Brazil; 2Department of Dermatology and Allergology, Academic Teaching Hospital Dresden-Friedrichstadt, Dresden, Germany Abstract: 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. Keywords: permanent makeup, cosmetic tattoos, adverse effects, dermatochalasis, Q-switched Nd:YAG laser

  19. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    B N Upadhyaya

    2014-01-01

    High-power laser generation using Yb-doped double-clad fibres with conversion efficiencies in excess of 80% have attracted much attention during the last decade due to their inherent advantages in terms of very high efficiency, no misalignment due to in-built intracore fibre Bragg gratings, low thermal problems due to large surface to volume ratio, diffraction-limited beam quality, compactness, reliability and fibre-optic beam delivery. Yb-doped fibres can also provide a wide emission band from ∼1010 nm to ∼1170 nm, which makes it a versatile laser medium to realize continuous-wave (CW), Q-switched short pulse, and mode-locked ultrashort pulse generation for various applications. In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical mechanisms involved in its generation has been described. A study on the generation of high-power CWfibre laser of 165Woutput power and generation of high peak power nanosecond pulses from acousto-optic Q-switched fibre laser has also been presented.

  20. 高稳定性的全光纤化调Q脉冲光纤激光器研究%Research on a high stability all-fiber Q-switched pulse fiber laser

    Institute of Scientific and Technical Information of China (English)

    张培培; 张鹏; 黄榜才; 王晓龙; 张雪莲; 龙润泽; 韩桂云; 梁小红

    2015-01-01

    搭建了一台高稳定性的全光纤调 Q 脉冲光纤激光器,采用光纤光栅和国产掺镱双包层光纤构成的线性 F-P 腔结构,以带尾纤的声光调制器(AOM)作为 Q 开关,并用915 nm 波长的多模半导体激光器进行端面泵浦,实现了中心波长1064 nm,平均功率1.4 W 的稳定脉冲激光输出。在重复频率20 kHz 的条件下,以该调 Q 激光器作为种子源,经过一级功率放大,最终获得了平均输出功率10.68 W,脉冲宽度120 ns 的激光输出,相应的脉冲能量为0.5 mJ,峰值功率为4.45 kW。并且该激光器在8 h 内的功率不稳定性为1.1%。%A high stable all-fiber Q-switched pulse fiber laser is reported.This laser uses a linear Fabry-Perot (F-P) cavity that is composed of the fiber Bragg grating and domestic ytterbium-doped double clad fiber.It takes pigtailed a-cousto-optic modulator (AOM)as Q-switch,meanwhile,it takes 915nm multimode laser diode (LD)as pumping source.The output of stable pulsed laser is achieved,whose center wavelength is 1064nm and the average output power is 1.4W.The output laser with the average power of 10.68W and the pulse width of 120ns is finally achieved at the repetition frequency of 20 kHz when the Q-switch laser is used as a seed source,corresponding to single pulse energy of 0.5mJ and peak power of 4.45 kW.And the fluctuation of laser power is 1.1% within 8 hours.

  1. Application of the multiple low-energy Q-switched laser for the treatment of tattoos in 21 cases%Q开关Nd:YAG激光低能量祛除21例文身疗效观察

    Institute of Scientific and Technical Information of China (English)

    丁娜娜; 麦跃; 杨鹏; 孙林潮; 陈瑞红

    2012-01-01

    Objective To evaluate the efficacy of multiple low-energy Q switched laser treatment for tattoo patients. Methods 21 patients (skin typelV-V, mean age 21.4) with tattoos were enrolled.and the tattoo lesions were divided into two parts on one person.: Lesions in part A (the experimental group) were treated with Q-switched laser (wavelength 1064nm .spotsize 4~6mm, fluence 2.0~4.0J/cm2, pulse repetition rate 10 Hz). The lesions became white-frosting after irradiation The treatment was performed once a day for 3 days.Lesions in part B (the control group) were treated with Q-switched laser (wavelength 1064nm, spotsize 3~4mm, fluence 5.0~8.0J/cm2 , pulse repetition rate 10 Hz) for one session. The evaluation was performed 6 months after treatment. Results In group A, all cases achieved different degree of improvement :42.8% of the tattoos were cured, 57.2% of the tattoos were excellent, without scar formation. In group B: all case achieved different degree of improvement :14.0% of the tattoos were cured, 24.0% of the tattoos were excellent and 62.0% of them were improved. Slightly hypertrophic scar formation occurred to 2 cases in group B. Conclusion Application of the multiple low-energy Q-switched laser is effective and safe in the treatment of tattoos , and the side effects was rare, thereby it give a new choice for the patients with tattoos .%目的:探讨Q开关Nd:YAG激光多次低能量祛除文身的临床疗效观察.方法:临床选取21例文身患者,治疗采用自身对比:A区为试验区,使用Q开关1064nm波长激光,光斑直径4~6mm,能量密度为2.0~4.0J/cm2,平行均匀照射1遍,术后即刻反应皮损变白霜,无皮肤出血点,每天治疗1次,连续治疗3~4次;B区为对照区,使用Q开关1064nm波长激光,光斑直径3~4mm,能量密度为5.0~8.0J/cm2,均匀照射1遍,即刻反应皮损灰白或皮肤出血.两组病例均于术后6个月观察疗效.结果:术后6个月观察,试验区:治愈9例(42.8%),显效12例(57.2%),无

  2. Q-switched mode-locked erbium-doped fiber laser based on topological insulator Bi(2)Se(3) deposited fiber taper.

    Science.gov (United States)

    Gao, Lei; Huang, Wei; Zhang, Jing Dong; Zhu, Tao; Zhang, Han; Zhao, Chu Jun; Zhang, Wei; Zhang, Hua

    2014-08-10

    We have demonstrated the passive Q-switching mode-locking operation in an erbium-doped fiber (EDF) laser by using topological insulator Bi(2)Se(3) deposited on fiber taper, whose damage threshold can be further increased by the large evanescent field interacting length. Due to the low saturation intensity, stable Q-switched mode-locked fiber lasers centered at 1562 nm can be generated at a pump power of 10 mW. The temporal and spectral characteristics for different pump strengths have also been investigated. To the best of our knowledge, it is the first time a Q-switched mode-locked EDF laser based on the fiber taper deposited by Bi(2)Se(3) was generated.

  3. Q-switched all-solid-state lasers and application in processing of thin-film solar cell

    Science.gov (United States)

    Liu, Liangqing; Wang, Feng

    2009-08-01

    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.

  4. Mode-locked and Q-switched operation of a diode laser pumped Nd:YAG laser operating at 1.064 µm

    Science.gov (United States)

    Maker, G. T.; Keen, S. J.; Ferguson, A. I.

    1988-10-01

    We describe the performance of a mode-locked and Q-switched Nd:YAG laser operating at 1.064 μm, optically pumped by a 500 mW diode laser. The cw mode-locked system provides bandwidth-limited pulses of 55 ps duration, with a corresponding peak power of 3.3 W. When Q-switched the energy within the 100 ns pulse envelope is 10 μJ giving a peak power in the largest pulse of 7 kW. Preliminary results for operation at 1.32 μm are also reported.

  5. Numerical Modelling of QCW-Pumped Passively Q-Switched Nd:YAG Lasers with Cr4+:YAG as Saturable Absorber

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-Ye; XU De-Gang; XIONG Jing-Ping; WANG Zhuo; WANG Peng; YAO Jian-Quan

    2008-01-01

    @@ Passively Q-switched quasi-continuous-wave (QCW) diode-pumped Nd:YAG laser with Cr4+:YAG as saturable absorber is numerically investigated by solving the coupled rate equations. The threshold pump rate for passively Q-switched QCW-pumped laser is derived. The effects of the pump rate and pump-pulse duration on the laser operation characteristics are studied theoretically. The pump power range can be estimated according to the number of output pulses. The numerical simulation results are in good agreement with the experimental results.

  6. MoS2 nanoflowers as high performance saturable absorbers for an all-fiber passively Q-switched erbium-doped fiber laser

    Science.gov (United States)

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

    2016-03-01

    Strong saturable absorption was observed in MoS2 nanoflowers, which were synthesized by a facile solvothermal method. A MoS2 nanoflower-based saturable absorber with a high modulation depth of 51.8% and a large saturable intensity of 275.5 GW cm-2 was introduced to the application of passively Q-switched fiber laser generation. Stable passively Q-switched fiber laser pulses at 1.56 μm with a low threshold power of 16.10 mW, high signal-to-noise ratio of 52.5 dB and short pulse duration of 1.9 μs were obtained. More importantly, a high output power of 3.10 mW related to a large pulse energy of about 51.84 nJ can be attained at a very low pump power. The efficiency of the laser reaches 4.71%, which is larger than that of the prepared layered MoS2 and recently reported MoS2-based passively Q-switching operations. Such results imply that the MoS2 nanoflowers are an excellent candidate for a saturable absorber in passively Q-switched fiber lasers at a low pump intensity.Strong saturable absorption was observed in MoS2 nanoflowers, which were synthesized by a facile solvothermal method. A MoS2 nanoflower-based saturable absorber with a high modulation depth of 51.8% and a large saturable intensity of 275.5 GW cm-2 was introduced to the application of passively Q-switched fiber laser generation. Stable passively Q-switched fiber laser pulses at 1.56 μm with a low threshold power of 16.10 mW, high signal-to-noise ratio of 52.5 dB and short pulse duration of 1.9 μs were obtained. More importantly, a high output power of 3.10 mW related to a large pulse energy of about 51.84 nJ can be attained at a very low pump power. The efficiency of the laser reaches 4.71%, which is larger than that of the prepared layered MoS2 and recently reported MoS2-based passively Q-switching operations. Such results imply that the MoS2 nanoflowers are an excellent candidate for a saturable absorber in passively Q-switched fiber lasers at a low pump intensity. Electronic supplementary

  7. High-power electronics

    CERN Document Server

    Kapitsa, Petr Leonidovich

    1966-01-01

    High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

  8. High Power Dye Lasers

    Science.gov (United States)

    1975-09-30

    art capabilities for developmental models of hydrogen thyratrons and solid state thyristors. Table II-l is a list of switches that have been... thyratron Table II-l Switch Ignitron GE, GL - 37207 Hydrogen Thyratron High Power Switches Peak Cur. (kA) RMS Cm. (A) 300 120 Max. Rep Rate...for 2 usec Pulse Cli„) 8 1. EG&G HY-5 2. EW. GHT9 3. EG&G Develop- mental model Thyristors 5 7.5 15 125 335 350 300 1000 300 RCA

  9. Nonlinear optical properties and Q-switch performance of silica glasses doped with CuxSe nanoparticles

    Science.gov (United States)

    Zolotovskaya, Svetlana A.; Savitski, Vasily G.; Prokoshin, Pavel V.; Yumashev, Konstantin V.; Gurin, Valerij S.; Alexeenko, Alexander A.

    2006-07-01

    Glasses containing copper selenide nanoparticles (CuxSe) reveal an intense absorption band peaking at 1 μm (1.24 eV). The transient bleaching and intensity-dependent transmission of silica glasses with CuxSe nanoparticles of different stoichiometry are studied with 1.08 μm (1.15 eV) picosecond pulses. The bleaching relaxation time decreases with a shift in the absorption band maximum to the lower photon energies. The dependence of absorption on the input energy of the pulses is saturationlike at the beginning of the plateau at ~40 mJ/cm2. Passive Q-switching of the Nd3+:KGd(WO4)2 laser at 1.067 μm is realized with the CuxSe-doped glasses for different x.

  10. Q-switched waveguide laser based on two-dimensional semiconducting materials: tungsten disulfide and black phosphorous.

    Science.gov (United States)

    Tan, Yang; Guo, Zhinan; Ma, Linan; Zhang, Han; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-02-01

    Owing to their unique properties, graphene-like two dimensional semiconducting materials, including Tungsten Disulfide (WS2) and Black Phosphorous (BP), have attracted increasing interest from basic research to practical applications. Herein, we demonstrated the ultrafast nonlinear saturable absorption response of WS2 and BP films in the waveguide structure. Through fabricating WS2 and BP films by evaporating the solutions on glass wafers. Saturable absorber films were attached onto the end-facet of the waveguide, which therefore constitutes a resonant cavity for the waveguide laser. Under a pump laser at 810 nm, we could obtain a stable Q-switched operation in the waveguide structure. This work indicated the significant potential of WS2 and BP for the ultrafast waveguide laser.

  11. 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.;

    2011-01-01

    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......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...

  12. Mode-locking and Q-switching in multi-wavelength fiber ring laser using low frequency phase modulation.

    Science.gov (United States)

    Jun, Chang Su; Kim, Byoung Yoon

    2011-03-28

    We describe experimental investigation of pulsed output from a multi-wavelength fiber ring laser incorporating low frequency phase modulation with large modulation amplitude. The Erbium-doped fiber (EDF) ring laser generated more than 8 wavelength channels with the help of a phase modulator operating at 26.2 kHz and a periodic intra-cavity filter. For most cases, the laser output is pulsed in the form of mode-locking at 5.62 MHz and/or Q-switching at harmonic and sub-harmonic of the phase modulation frequency. Chaotic pulse output is also observed. The behavior of the output pulses are described as functions of pump power and phase modulation amplitude. The relative intensity noise (RIN) value of a single wavelength channel is measured to be under -100 dB/Hz (-140 dB/Hz beyond 1.5 GHz).

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

    Science.gov (United States)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas T; Scolari, Lara; Cocquelin, Benjamin; Salin, Francois; Broeng, Jes; Lægsgaard, Jesper

    2011-05-23

    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 59μm. 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.

  14. Wavelength Spacing Tunable, Multiwavelength Q-Switched Mode-Locked Laser Based on Graphene-Oxide-Deposited Tapered Fiber

    CERN Document Server

    Gao, Lei; Zeng, Jing

    2014-01-01

    A wavelength spacing tunable, multiwavelength Q-switched mode-locked (QML) fiber laser in an erbium-doped fiber cavity based on graphene oxide deposited on tapered fiber is proposed by choosing the diameter and length of the taper, graphene oxide thickness and cavity dispersion, in which the wavelength spacing could be tuned by pump power. The evolutions of temporal and spectral with different pump strengths are investigated. Results show that the tunability of the multiwavelength laser can be interpreted by the bound states of QML laser resulting from a mutual interaction of dispersion, nonlinear effect, insertion loss, and pump power. To the best of our knowledge, it is the first experimental observation of bound states of QML, which provides a new mechanism to fabricate tunable multiwavelength laser.

  15. Narrow-band 1 W source at 257 nm using frequency quadrupled passively Q-switched Yb:YAG laser.

    Science.gov (United States)

    Goldberg, Lew; Cole, Brian; McIntosh, Chris; King, Vernon; Hays, A D; Chinn, Stephen R

    2016-07-25

    We describe generation of 1.1 W of 257 nm emission by frequency quadrupling the 1030 nm emission from a compact passively Q-switched Yb:YAG laser. The laser utilized a volume Bragg grating to achieve a 0.1 nm linewidth required for UV-Raman spectroscopic applications, generated 100 kW peak power, 250 μJ pulses and 3.6 W of average power at 1030 nm. Fourth harmonic generation (FHG) was carried out using a 10 mm lithium triborate (LBO) crystal to generate 515 nm second harmonic with 70% conversion efficiency, followed by a 7 mm beta-barium borate (BBO) crystal to generate 257 nm fourth harmonic with 45% efficiency, resulting in an overall nonlinear conversion efficiency of 31%. Far-field and near-field of the FHG emission were characterized.

  16. Effect of Q-switched Alexandrite laser irradiation on epidermal melanocytes in treatment of Nevus of Ota

    Institute of Scientific and Technical Information of China (English)

    卢忠; 陈军庞; 王侠生; 方丽华; 焦圣; 黄雯

    2003-01-01

    Objective To investigate injury to epidermal melanocyte by Q-switched Alexandrite laser.Methods Multiple biopsies were performed on 5 patients with nevus of Ota from before irradiation to 1 year after irradiation. Fourteen specimens were obtained for light microscopy, and 17 for transmission electron microscopy.Results Melanosomes in epidermal melanocytes were both smaller in size and fewer in number than those in dermal melanocytes. Immediately after irradiation, focal extracellular vacuoles of the basal layer could be observed under light microscopy. Most epidermal melanocytes underwent mild or moderate injury in the form of vacuolated melanosomes, swollen mitochondria, dilation of endoplasmic reticulum, and expansion of extracellular space, retaining intact cell membranes. Normal structures were restored 5 months to 1 year after irradiation, with no depigmentation or hyperpigmentation as seen by light microscopy.Conclusion Injury of melanosomes in epidermal melanocytes is reversible.

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

    Science.gov (United States)

    Goldman, Alberto; Wollina, Uwe

    2014-01-01

    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. PMID:25143716

  18. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser.

    Science.gov (United States)

    Goldman, Alberto; Wollina, Uwe

    2014-01-01

    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.

  19. Treatment of Laugier-Hunziker syndrome with the Q-switched alexandrite laser in 22 Chinese patients.

    Science.gov (United States)

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

    2010-03-01

    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.

  20. End-pumped all solid-state high repetition rate Tm, Ho:LuLF laser

    Institute of Scientific and Technical Information of China (English)

    Shijiang Shu; Ting Yu; Junyan Hou; Rongtao Liu; Minjie Huang; Weibiao Chen

    2011-01-01

    @@ The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78 μJ under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed.%The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78μJ under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed.

  1. High power coaxial ubitron

    Science.gov (United States)

    Balkcum, Adam J.

    In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along

  2. Resonant High Power Combiners

    CERN Document Server

    Langlois, Michel; Peillex-Delphe, Guy

    2005-01-01

    Particle accelerators need radio frequency sources. Above 300 MHz, the amplifiers mostly used high power klystrons developed for this sole purpose. As for military equipment, users are drawn to buy "off the shelf" components rather than dedicated devices. IOTs have replaced most klystrons in TV transmitters and find their way in particle accelerators. They are less bulky, easier to replace, more efficient at reduced power. They are also far less powerful. What is the benefit of very compact sources if huge 3 dB couplers are needed to combine the power? To alleviate this drawback, we investigated a resonant combiner, operating in TM010 mode, able to combine 3 to 5 IOTs. Our IOTs being able to deliver 80 kW C.W. apiece, combined power would reach 400 kW minus the minor insertion loss. Values for matching and insertion loss are given. The behavior of the system in case of IOT failure is analyzed.

  3. MoS2 nanoflowers as high performance saturable absorbers for an all-fiber passively Q-switched erbium-doped fiber laser.

    Science.gov (United States)

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

    2016-04-14

    Strong saturable absorption was observed in MoS2 nanoflowers, which were synthesized by a facile solvothermal method. A MoS2 nanoflower-based saturable absorber with a high modulation depth of 51.8% and a large saturable intensity of 275.5 GW cm(-2) was introduced to the application of passively Q-switched fiber laser generation. Stable passively Q-switched fiber laser pulses at 1.56 μm with a low threshold power of 16.10 mW, high signal-to-noise ratio of 52.5 dB and short pulse duration of 1.9 μs were obtained. More importantly, a high output power of 3.10 mW related to a large pulse energy of about 51.84 nJ can be attained at a very low pump power. The efficiency of the laser reaches 4.71%, which is larger than that of the prepared layered MoS2 and recently reported MoS2-based passively Q-switching operations. Such results imply that the MoS2 nanoflowers are an excellent candidate for a saturable absorber in passively Q-switched fiber lasers at a low pump intensity.

  4. High-repetition-rate femtosecond dye amplifier using a laser-diode-pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.

    1989-02-06

    A high-repetition-rate femotosecond dye amplifier is demonstrated using a laser-diode-pumped Q-switched Nd:YAG laser. Amplification of wavelength-tunable 300-fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  5. Overview on the high power excimer laser technology

    Science.gov (United States)

    Liu, Jingru

    2013-05-01

    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  6. A randomized, split-face clinical trial of Q-switched alexandrite laser versus Q-switched Nd:YAG laser in the treatment of bilateral nevus of Ota.

    Science.gov (United States)

    Wen, Xiang; Li, Yong; Jiang, Xian

    2016-01-01

    Different types of Q-switched (QS) lasers have been used successfully to treat nevus of Ota. The purpose of this study was to compare the clinical efficacy and complication of QS alexandrite (QS Alex) laser versus QS neodymium:yttrium aluminum garnet (Nd:YAG) (QS Nd:YAG) laser for bilateral nevus of Ota. Seventeen patients with bilateral nevus of Ota were treated randomly with QS Alex in one half of face and QS Nd:YAG in the other half with an interval of at least 3 months between each. Subjective assessment was made by both patients and dermatologists. Patients were also examined for evidence of complications. All patients experienced improvement (p 0.05). The pain after a short period of laser therapy was more severe for QS Alex than for QS Nd:YAG laser. Vesicles developed in 1 patient after QS Alex therapy. Both QS Alex laser and QS Nd:YAG laser were equally effective at improving bilateral nevus of Ota. Patients tolerate QS Nd:YAG laser better than QS Alex laser.

  7. A dual-loss-modulated intra-cavity frequency-doubled Q-switched and mode-locked Nd:Lu0.15Y0.85VO4/KTP green laser with a single-walled carbon nanotube saturable absorber and an acousto-optic modulator

    Science.gov (United States)

    Zhang, Gang; Zhao, Shengzhi; Yang, Kejian; Li, Guiqiu; Li, Dechun; Cheng, Kang; Han, Chao; Zhao, Bin; Wang, Yonggang

    2011-09-01

    By using both a single-walled carbon nanotube saturable absorber (SWCNT-SA) and an acousto-optic (AO) modulator, a dual-loss-modulated intra-cavity frequency-doubled Q-switched and mode-locked (QML) Nd:Lu0.15Y0.85VO4/KTP (KTiOPO4) green laser was demonstrated for the first time. The QML green laser characteristics such as the pulse width and single-pulse energy have been measured for different modulation frequencies of the AO modulator (fp). In particular, in comparison with the solely passively QML green laser with an SWCNT-SA, the dual-loss-modulated QML green laser can generate a more stable pulse train, a shorter pulse width of the Q-switched envelope, a greater pulse energy and a higher average peak power. For the dual-loss-modulated QML green laser, at a pump power of 7.9 W and a repetition rate of 10 kHz, the pulse width and the pulse energy of the Q-switch envelope and the average peak power of the QML green laser are 50 ns, 20.34 µJ and 15.5 kW, respectively, corresponding to a pulse width compression of 77%, a pulse energy improvement factor of six times and a QML peak power increase factor of 16 times when compared with those for the solely passively QML green laser. The experimental results show that the dual-loss modulation is an efficient method for the generation of a stable QML green laser with an SWCNT-SA.

  8. High power evaluation of X-band high power loads

    CERN Document Server

    Matsumoto, Shuji; Syratchev, Igor; Riddone, Germana; Wuensch, Walter

    2010-01-01

    Several types of X-band high power loads developed for several tens of MW range were designed, fabricated and used for high power tests at X-band facility of KEK. Some of them have been used for many years and few units showed possible deterioration of RF performance. Recently revised-design loads were made by CERN and the high power evaluation was performed at KEK. In this paper, the main requirements are recalled, together with the design features. The high power test results are analysed and presented

  9. Mechanically exfoliated black phosphorus as a new saturable absorber for both Q-switching and Mode-locking laser operation.

    Science.gov (United States)

    Chen, Yu; Jiang, Guobao; Chen, Shuqing; Guo, Zhinan; Yu, Xuefeng; Zhao, Chujun; Zhang, Han; Bao, Qiaoliang; Wen, Shuangchun; Tang, Dingyuan; Fan, Dianyuan

    2015-05-18

    Black phosphorus (BP), an emerging narrow direct band-gap two-dimensional (2D) layered material that can fill the gap between the semi-metallic graphene and the wide-bandgap transition metal dichalcogenides (TMDs), had been experimentally found to exhibit the saturation of optical absorption if under strong light illumination. By taking advantage of this saturable absorption property, we could fabricate a new type of optical saturable absorber (SA) based on mechanically exfoliated BPs, and further demonstrate the applications for ultra-fast laser photonics. Based on the balanced synchronous twin-detector measurement method, we have characterized the saturable absorption property of the fabricated BP-SAs at the telecommunication band. By incorporating the BP-based SAs device into the all-fiber Erbium-doped fiber laser cavities, we are able to obtain either the passive Q-switching (with maximum pulse energy of 94.3 nJ) or the passive mode-locking operation (with pulse duration down to 946 fs). Our results show that BP could also be developed as an effective SA for pulsed fiber or solid-state lasers.

  10. Bundled hollow optical fibers for transmission of high-peak-power Q-switched Nd:YAG laser pulses.

    Science.gov (United States)

    Yilmaz, Ozgur; Miyagi, Mitsunobu; Matsuura, Yuji

    2006-09-20

    A hollow-fiber bundle was designed and used to deliver high-peak-power pulses from a Q-switched Nd:YAG laser. An 80 cm long bundle with a total diameter of 5.5 mm was composed of 37 glass capillaries with bore diameters of 0.7 mm. Beam-resizing optics with two lenses were used to couple the laser beam into the bundle. The measured coupling loss due to the limited aperture ratio of the bundle was 2.3 dB, and the transmission loss at wavelengths of 1064 and 532 nm was 0.3 dB. When an inert gas flowed through the bores of the capillaries, the maximum output pulse energy was 200 mJ, which was the limit of the laser used in the experiment. Hollow-fiber bundles withstand irradiation better than single hollow fibers and silica-glass optical fibers do. They are suitable for many dermatological applications because they can be used to irradiate a large area.

  11. Low-pulse energy Q-switched Nd:YAG laser treatment for hair-dye-induced Riehl's melanosis.

    Science.gov (United States)

    On, Hye Rang; Hong, Won Jin; Roh, Mi Ryung

    2015-06-01

    Riehl's melanosis, a form of dermatitis characterized by reticulate pigmentation, typically presents as a gray-brown to black hyperpigmentation on the face and neck. Among the various etiologic factors suggested, photoallergic reaction and pigmented contact dermatitis resulting from exposure to drugs, coal tar dyes, optical whitener, or other ingredients found in cosmetics are believed to be the major contributing factors in this disease. The histopathological features of Riehl's melanosis mainly consist of pigmentary incontinence along with infiltration of numerous dermal melanophages and lymphohistiocytes.1,2 Additionally, notable clinical improvements in the treatment of this condition have been reported for intense pulsed light (IPL) therapy, in comparison to long-term topical application of bleaching agents.2 Here, we report the cases of two Asian patients treated with a low-pulse energy 1,064-nm Q-switched (QS) Nd:YAG laser for hair dye-induced Riehl's melanosis on the face and neck. In conclusion, we observed that Riehl's melanosis on the face and neck was effectively and safely treated with a low-pulse energy 1,064-nm QS Nd:YAG laser. We suggest that this method can be used in Asian patients with Riehl's melanosis at risk of postinflammatory hyperpigmentation from excessive light or laser energy delivery.

  12. Scaling and passively Q-switch operation of a Nd:YAG laser pumped laterally through a YAG prism

    Science.gov (United States)

    Dascalu, T.; Salamu, G.; Sandu, O.; Dinca, M.; Pavel, N.

    2015-04-01

    We report on scaling of a laser configuration in which a YAG prism is used to couple the pump beam from a fiber-coupled diode laser directly into a Nd:YAG medium. Several resonator geometries have been investigated. In free generation regime laser pulses at 1.06 μm with energy of 22.1 mJ for the pump energy of 44.6 mJ were obtained from a 10.0 mm long, 1.0-at% Nd:YAG single crystal that had the high-reflectivity mirror coated directly on one of the laser crystal surface. The slope efficiency was 0.51. A similar uncoated Nd:YAG crystal placed in a plane-plane resonator delivered laser pulses with 17.8 mJ energy under the pump with 45.4 mJ energy, at 0.40 slope efficiency. Further, a passively Q-switched Nd:YAG/Cr4+:YAG composite ceramic laser pumped through a YAG prism has been built. Using a Cr4+:YAG saturable absorber of 0.85 initial transmission the device delivered laser pulses with 0.29 mJ energy and 11 ns duration. The output performances are compared to those obtained in a classical end-pumping scheme.

  13. Dynamic photopatterning of cells in situ by Q-switched neodymium-doped yttrium ortho-vanadate laser

    Science.gov (United States)

    Deka, Gitanjal; Okano, Kazunori; Kao, Fu-Jen

    2014-01-01

    Cellular micropattering has been increasingly adopted in quantitative biological experiments. A Q-switched pulsed neodymium-doped yttrium ortho-vanadate (Nd) laser directed in-situ microfabrication technique for cell patterning is presented. A platform is designed uniquely to achieve laser ablation. The platform is comprised of thin gold coating over a glass surface that functions as a thermal transducer and is over-layered by a cell repellant polymer layer. Micropatterns are engraved on the platform, subsequently exposing specific cell adhesive micro-domains by ablating the gold-polymer coating photothermally. Experimental results indicate that the proposed approach is applicable under culture conditions, viable toward cells, and has a higher engraving speed. Possible uses in arraying isolated single cells on the platform are also shown. Additionally, based on those micro-patterns, dynamic cellular morphological changes and migrational speed in response to geometrical barriers are studied to demonstrate the potential applications of the proposed approach. Our results further demonstrate that cells in narrower geometry had elongated shapes and higher migrational speed than those in wider geometry. Importantly, the proposed approach will provide a valuable reference for efforts to study single cell dynamics and cellular migration related processes for areas such as cell division, wound healing, and cancer invasion.

  14. Pulsed pumped Yb-doped fiber amplifier at low repetition rate

    Institute of Scientific and Technical Information of China (English)

    Changgeng Ye; Ping Yan; Mali Gong; Ming Lei

    2005-01-01

    A pulsed pumped Yb-doped double-clad fiber (DCF) master-oscillator power amplifier (MOPA) at low repetition rate is reported. Seeded by a passive Q-switched Nd:YAG microchip laser, the fiber amplifier can generate 167-kW peak-power and 0.83-ns duration pulses at 200-Hz repetition rate. Because of the pulsed pump approach, the amplified spontaneous emission (ASE) and the spurious lasing between pulses are well avoided, and the repetition rate can be set freely from single-shot to 1 kHz. Peak power scaling limitations that arise from the fiber facet damage are discussed.

  15. Compact intra-cavity pumped low-threshold passively Q-switched Ho:Sc2SiO5 laser by a LD-pumped Tm:YAP laser at room temperature

    Science.gov (United States)

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

    2017-08-01

    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.

  16. 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.

    Science.gov (United States)

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

    2010-11-01

    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.

  17. Effect of Buffer Layer on Epitaxial Growth of YSZ Deposited on Si Substrate by Slower Q-switched 266 nm YAG Laser

    Science.gov (United States)

    Kaneko, Satoru; Akiyama, Kensuke; Shimizu, Yoshitada; Ito, Takeshi; Yasaka, Shinji; Mitsuhashi, Masahiko; Ohya, Seishiro; Saito, Keisuke; Watanabe, Takayuki; Okamoto, Shoji; Funakubo, Hiroshi

    2004-04-01

    Yttria-stabilized zirconia (YSZ) was grown on Si(100) substrate by pulsed laser deposition (PLD). The laser used in this study was a 266 nm YAG laser with a second function generator modulating only the Q-switch while the primary generator modulated the flash lamp (slower Q-switch). Epitaxial growth was verified on YSZ film deposited without oxygen gas followed by primary deposition in oxygen atmosphere on Si substrate with a ˜0.4-nm-thin oxide layer. The crystallinity was strongly dependent on the thickness of the buffer layer deposited prior to the primary deposition of YSZ. The epitaxial growth was confirmed by φ scan, and ω scan (rocking curve) showed the full width at half maximum (FWHM) of 1.1 deg. The required oxygen pressure for epitaxial growth was quite high compared to that of excimer deposition.

  18. As-grown uniform MoS2/mica saturable absorber for passively Q-switched mode-locked Nd:GdVO4 laser

    Science.gov (United States)

    Xu, Yuanyuan; Yang, Cheng; Ge, Pengguang; Liu, Jie; Jiang, Shouzhen; Li, Chun; Man, Baoyuan

    2016-08-01

    Molybdenum disulfide (MoS2) has recently attracted growing attention due to its distinctive properties and potential applications in optoelectronics and electronics. Here, large-area and high-quality MoS2 film with uniform thickness was obtained by thermally decomposing ammonium thiomolybdate. Besides, it is firstly demonstrated that the as-grown MoS2/mica can be directly inserted into Nd:GdVO4 laser cavity as saturable absorber for the output of diode-pumped passively Q-switched mode-locked pulse trains. Using the MoS2 saturable absorbers, the stable Q-switched mode-locked pulse trains with high modulation depth were realized, suggesting that the broadband MoS2 SA could potentially be employed in mode-locking laser system

  19. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

    Science.gov (United States)

    Woodruff, Steven D.; Mcintyre, Dustin L.

    2016-03-29

    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.

  20. Bindi tattoo on forehead: Success with modified R-20 technique using low fluence Q-switched Nd YAG laser: A case report

    Directory of Open Access Journals (Sweden)

    Vijay Zawar

    2014-01-01

    Full Text Available 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.

  1. Passively Q-switched Erbium-doped and Ytterbium-doped fibre lasers with topological insulator bismuth selenide (Bi2Se3) as saturable absorber

    Science.gov (United States)

    Haris, H.; Harun, S. W.; Muhammad, A. R.; Anyi, C. L.; Tan, S. J.; Ahmad, F.; Nor, R. M.; Zulkepely, N. R.; Arof, H.

    2017-02-01

    This paper portrays a simple Q-switched Erbium-doped fibre (EDF) and Ytterbium doped fibre (YDF) lasers by using topological insulator (TI) Bismuth Selenide (Bi2Se3) as saturable absorber. The modulation depth of the fabricated Bi2Se3 is about 39.8% while its saturating intensity is about 90.2 MW/cm2. By depositing the TI Bi2Se3 SA onto fibre ferrules and incorporate it inside the proposed cavity, a stable Q-switching operation was achieved at 1 μm and 1.5 μm. The fabricated Bismuth Selenide (Bi2Se3) as saturable absorber (SA) is a broadband SA where it offers a compact and low cost fabrication which is beneficial in various photonic applications.

  2. Passively Q-Switched Nd∶YAG Microchip Laser Based on Graphene%基于石墨烯被动调Q Nd∶YAG晶体微片激光器

    Institute of Scientific and Technical Information of China (English)

    曹镱; 刘佳; 刘江; 王璞

    2012-01-01

    设计了以石墨烯作为可饱和吸收体的被动调Q掺钕钇铝石榴石晶体(Nd∶YAG)微片激光器.该激光器采用三明治结构,附有石墨烯薄层的YAG晶体紧密压贴于工作物质Nd∶YAG晶体上,晶体端面镀膜作为端面镜构成平行平面谐振腔.采用光纤耦合输出激光二极管端面抽运技术,利用石墨烯的可饱和吸收作用,在注入功率为1.17W时实现微片激光器的调Q运转,获得波长1064.6nm,重复频率300~807kHz可调,最小脉冲宽度75ns的激光输出.激光器最大输出功率38.4mW,最大单脉冲能量54.7nJ.%A design passively Q-switched Nd ! YAG microchip laser based on graphene saturable absorber is presented. A thin layer of graphene is sandwiched between the Nd! YAG crystal and YAG crystal closely, and dichroic coatings on crystals is used as reflective mirrors for the plane parallel resonator. The Nd'YAG crystal is end pumped by a fiber-coupled laser diode via a lens imaging system. Employing graphene as saturable absorber, Q-switched Nd: YAG microchip laser is realized at the pump power threshold of 1.17 W with laser central wavelength of 1064.6 nm. The minimum pulse duration is 75 ns at 488 kHz and the repetition rate is tunable from 300 to 807 kHz with the increase of the pump power. The maximum output power and highest pulse energy of the laser measured are 38.4 mW and 54.7 nj, respectively.

  3. New insight in the treatment of refractory melasma: Laser Q-switched Nd: YAG non-ablative fractionated followed by intense pulsed light.

    Science.gov (United States)

    Cunha, Paulo Rowilson; Pinto, Clovis Antonio Lopes; Mattos, Camila Bonati; Cabrini, Dayane Peverari; Tolosa, Joana Lugli

    2015-01-01

    The purpose of our study was to verify the results of the association of Q-switched Nd: YAG non-ablative fractionated with intense pulsed light, in order to treat patients with refractory melasma. The combination of these two devices seems to be the best treatment to combat hyperpigmentation produced by melasma, with low occurrence of side effects, which may be justified by the selective photothermolysis at subcellular level.

  4. Energy reduction: a technique for seed-injection locking of single-axial-mode Q-switched Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Sui Chen; Wenxiong Lin; Fei Shi; Jianhong Huang; Jinhui Li; Hui Zheng; Jipeng Lin; Canhua Xu

    2007-01-01

    A new technique for seed-injection locking of single-axial-mode (SAM) Q-switched Nd:YAG laser is reported. The technique called energy reduction (ER) is utilized when SAM operation is locked to design its feedback scheme. This method ensures long-term 100% seed-injection locking performance and the pulsed SAM output energy can reach as high as 200 mJ. Both temporal and spatial interferometric experiments have been executed to confirm the SAM oscillation.

  5. Modulated Pulse Generations in a Laser-diode-pumped Passively Q-switched Intracavity-frequency-doubling Nd∶YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    郑加安; 赵圣之; 陈磊

    2002-01-01

    The investigative results of modulated pulse output from an LD end-pumped passively Q-switched intracavity-frequency-doubling Nd∶YVO4/KTP laser with Cr4+∶YAG saturable absorber are presented. The numerical stimulations of these modulated pulses are carried out basing on the rate equations. It indicated that the modulations are attribute to the frequency beating of two eigenstates of the resonant polarized modes. The theoretical calculations are in good agreement with the experimental observations.

  6. Successful Treatment of Tattoo-Induced Pseudolymphoma with Sequential Ablative Fractional Resurfacing Followed by Q-Switched Nd: YAG 532 nm Laser

    OpenAIRE

    2013-01-01

    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 an...

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

    Science.gov (United States)

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

    2017-01-01

    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 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:YVO4 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 VO2 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, WS2) 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 VO2 as low-cost saturable absorber for subnanosecond laser generation. PMID:28383017

  8. Q开关激光治疗太田痣的临床分析%Clinical Analysis of Q Switch Laser in Treatment of Nevus of Ota

    Institute of Scientific and Technical Information of China (English)

    高微

    2015-01-01

    Objective To analyze the clinical effect of Q switch laser in treating patients with too much field mole.Methods To adopt the Q switch Nd:YAG 1 064 nm laser treatment on 280 patients.ResultsWith the increase of the number of patients with treatment the cure rate and total effective rate increased more than 6 times,the treatment,the cure rate was 96.7%,the total efficiency of 100%. Conclusion The Q switch Nd:YAG 1 064 nm laser in treatment of nevus of ota high.%目的:分析Q开关激光治疗太田痣的临床疗效。方法对280例太田痣患者采取Q开关Nd:YAG 1064 nm激光治疗。结果随着治疗次数的增加患者痊愈率及总有效率随之提高,治疗6次以上,痊愈率96.7%,总有效率100%。治疗后无瘢痕。结论 Q开关Nd:YAG 1064 nm激光治疗太田痣疗效高。

  9. Fractional CO2 laser is as effective as Q-switched ruby laser for the initial treatment of a traumatic tattoo.

    Science.gov (United States)

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

    2014-12-01

    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.

  10. Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

    Science.gov (United States)

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

    2017-04-01

    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 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:YVO4 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 VO2 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, WS2) 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 VO2 as low-cost saturable absorber for subnanosecond laser generation.

  11. Morphologic Changes of Zebrafish Melanophore after Intense Pulsed Light and Q-Switched Nd:YAG Laser Irradiation

    Science.gov (United States)

    Ryu, Hwa Jung; Lee, Ji Min; Jang, Hee Won; Park, Hae Chul; Rhyu, Im Joo

    2016-01-01

    Background Recently, the pulse-in-pulse mode of intense pulsed light (IPL) has been used increasingly for the treatment of melasma. Objective To observe the morphologic changes in the melanophore in adult zebrafish after irradiation with conventional and pulse-in-pulse IPL and Q-switched Nd:YAG (QSNY) laser. Methods Adult zebrafish were irradiated with conventional and pulse-in-pulse mode of IPL. The conditions for conventional IPL were 3 mJ/cm2, 560 nm filter, and pulse widths of 7, 20, and 35 msec. The pulse-in-pulse conditions were 3 mJ/cm2 and on-time 1/off-time 2. The QSNY laser was used with the settings of 1,064 nm, 0.4 J/cm2, a 7 mm spot size, and one shot. Specimens were observed using a light microscope, a transmission electron microscope (TEM), a scanning electron microscope (SEM) and a confocal microscope. Results After conventional IPL irradiation with a 7 msec pulse width, melanophore breakage was observed using light microscopy. Under TEM, irradiation with conventional IPL for 7 msec and pulse-in-pulse IPL induced melanophore thermolysis with vacuolization. However, changes in the melanophore were not observed with 35 msec IPL. Under SEM, unlike the control and QSNY groups, IPL-irradiated zebrafish showed finger-like fusion in the protein structure of scales. Specimens examined by a confocal microscope after conventional IPL irradiation showed a larger green-stained area on TUNEL staining than that after pulse-in-pulse mode IPL irradiation. Conclusion Zebrafish irradiated with long pulse-IPL showed no morphologic changes using light microscopy, while morphological changes in melanophores were evident with use of TEM. Pulse-in-pulse mode IPL caused less damage than conventional IPL. PMID:27904270

  12. Effectiveness of combined pulsed dye and Q-switched ruby laser treatment for large to giant congenital melanocytic naevi.

    Science.gov (United States)

    Funayama, E; Sasaki, S; Furukawa, H; Hayashi, T; Yamao, T; Takahashi, K; Yamamoto, Y; Oyama, A

    2012-11-01

    There is no consensus on the most appropriate treatment for patients with large to giant congenital melanocytic naevi (CMN) because of the risk of melanoma development. Surgical excision followed by skin grafting or expanded skin coverage may cause unfavourable scarring. There is a balance to be achieved between minimizing the disfiguring appearance and the risk of malignant change. The pulsed dye laser (PDL) is commonly used for vascular lesions and is highly absorbed by melanin and haemoglobin. Its pulse duration is longer than that of Q-switched ruby lasers (QsRL), which can have nonspecific photothermolytic effects on surrounding nonpigmented naevus cells. To investigate the effectiveness of combined treatment with the PDL and QsRL for large to giant CMN. Six patients with large to giant CMN were enrolled in this study. Treatment consisted of one pass of PDL treatment followed by one pass of QsRL treatment. Multiple rounds of treatment were applied to all patients. All patients responded to this combined regimen, and the lesional colour was effectively reduced. The mean number of rounds of laser treatment required to achieve skin lightening was 7·7. No patients suffered severe hypertrophic scarring. No cases of recurrence or malignant transformation were observed. The histological results from the patient who underwent the most laser therapy in this study showed a remarkable reduction in the number of melanocytic naevus cells after treatment. This technique may enable the removal of most of the pigmented lesion and melanocytic naevus cells with minimal scarring. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.

  13. End-pumped Nd:YAG Q-switched laser with high energy and narrow pulse for glass carving

    Science.gov (United States)

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

    2009-05-01

    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.

  14. Nevus of Ota resistant to multiple sessions of Q-switched laser treatment: two case reports%Q开关激光多疗程治疗太田痣无效二例

    Institute of Scientific and Technical Information of China (English)

    胡玲玲; 宋为民; 沈静; 郑涵; 陈俊帆

    2011-01-01

    Two cases of nevus of Ota resistant to multiple sessions of Q-switched laser treatment are reported.Both of the patients were females,who developed beige or blue patches on the left side of the face (zygomatic region,cheek)several months after birth.No conjunctiva or sclera was involved.The lesions spread to the left retroauricular region and posterior neck during pregnancy in one patient.Histopathological examination of the lesions showed scattered melanocytes and melanophages in lower dermis and subcutaneous adipose tissue as well as apparent proliferation of collagen.Immunostaining for CD34 showed no abnormality in the distribution of vascular endothelial cells in these tissues.No obvious improvement was observed in either of the patient after more than 10 sessions(12 sessions in 1 case,and 13 sessions in the other case)of treatments with Q-switched alexandrite(755 nm)or Q-switched Nd:YAG laser(1064 nm).The immediate response of lesions to laser irradiation was unusual.Purpura or errhysis was absent in the lesions after repetitive irradiation with high-energy laser,but both were visible in the adjacent normal skin even after irradiation with low-energy laser.%报道2例激光治疗多次无效的太田痣.患者均为女性,均在出生后数月发病,累及左侧面部,皮损表现为颧部、面颊部灰褐色至褐青色斑片,巩膜无蓝染.1例怀孕期斑片扩展至左耳后及左颈后.组织病理显示真皮深层及皮下脂肪组织间散在分布黑素细胞及噬黑素细胞,胶原纤维明显增生.免疫组化CD34标记血管内皮细胞分布无异常.对一般用于太田痣的激光治疗反应差.Q开关翠绿宝石激光(波长755 nm)和或Q开关Nd:YAG激光(波长1064 nm)累计治疗10余次几乎无效(1例治疗12次,1例治疗13次),且激光即刻反应特殊,即使高能量多次重复照射,皮疹处均无紫癜或渗血,而周围正常皮肤较低能量下即可见明显的紫癜和渗血.

  15. Treatment of melasma in Caucasian patients using a novel 694-nm Q-switched ruby fractional laser

    Science.gov (United States)

    2013-01-01

    Background Melasma is a common hypermelanosis of the face. The use of a classical Q-switched ruby laser (QSRL) to treat melasma is discussed controversially and is associated with frequent adverse effects, such as hyper- or hypopigmentation. Recently a fractional-mode (FRx) QSRL was developed to minimize the adverse effects of classical QSRL. The objective of this research was to evaluate the efficacy and safety of a novel FRx-QSRL in the treatment of melasma in Caucasian patients. Methods We performed a retrospective study of 25 Caucasian melasma patients (Fitzpatrick skin types I to III). Patients received one to three FRx-QSRL treatments (Tattoostar FRx, Asclepion Laser Technologies, Jena, Germany) at pulse energies of 4 to 8 J/cm2. Three blinded investigators independently evaluated the melasma area and severity index (MASI) score before treatment and at the four- to six-week follow-ups. At additional three-month follow-ups, patients evaluated subjective improvement, pain and over-all satisfaction with the treatment according to a numeric analogue score (NAS). Side effects were documented. Results At four to six weeks post laser treatment for a mean of 1.4 sessions, we observed a significant (P = 0.0001) reduction of the MASI score from 6.54 to 1.98 (72.3%). Patients rated the pain of the intervention at a mean 2.46 points (0 = no pain; 10 = maximum pain), the improvement at a mean 5.55 points (0 = no improvement; 10 = maximum improvement) and the overall satisfaction at a mean 4.66 points (0 = not satisfied; 10 = maximum satisfaction). After three months, post-inflammatory hyperpigmentation (PIH) and/or recurring melasma were observed in 7 (28%) and 11 (44%) patients, respectively. Conclusion The 694-nm FRx-QSRL is a safe and effective option for treating melasma in Caucasian patients. Over periods of >3 months, PIH and/or recurring melasma may develop at significant rates and may reduce patient satisfaction. Multiple treatment

  16. 157 W all-fiber high-power picosecond laser.

    Science.gov (United States)

    Song, Rui; Hou, Jing; Chen, Shengping; Yang, Weiqiang; Lu, Qisheng

    2012-05-01

    An all-fiber high-power picosecond laser is constructed in a master oscillator power amplifier configuration. The self-constructed fiber laser seed is passively mode locked by a semiconductor saturable absorber mirror. Average output power of 157 W is obtained after three stages of amplification at a fundamental repetition rate of 60 MHz. A short length of ytterbium double-clad fiber with a high doping level is used to suppress nonlinear effects. However, a stimulated Raman scattering (SRS) effect occurs owing to the 78 kW high peak power. A self-made all-fiber repetition rate increasing system is used to octuple the repetition rate and decrease the high peak power. Average output power of 156.6 W is obtained without SRS under the same pump power at a 480 MHz repetition rate with 0.6 nm line width.

  17. High-peak-power, high-repetition-rate intracavity optical parametric oscillator at 1.57μm

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Degang Xu; Yizhong Yu; Wuqi Wen; Jingping Xiong; Peng Wang; Jianquan Yao

    2007-01-01

    We report a high-peak-power, high-repetition-rate diode-side-pumped Nd:YAG Q-switched intracavity optical parametric oscillator (IOPO) at 1.57μm with a type-Ⅱ non-critically phase-matched x-cut KTP crystal. The average power of 1.15 W at 1.57μm is obtained at 4.3-kHz repetition rate. The peak power of the pulses amounts to 33.4 kW with 8-ns duration. The average conversion efficiency from Q-switched 1.064-μm-wavelength input power to OPO signal output power is up to 10.5%.

  18. High Power Widely Tunable Narrow Linewidth All-Solid-State Pulsed Titanium-Doped Sapphire Laser

    Institute of Scientific and Technical Information of China (English)

    DING Xin; LI Xue; SHENG Quan; SHI Chun-Peng; YIN Su-Jia; LI Bin; YU Xuan-Yi; WEN Wu-Qi; YAO Jian-Quan

    2011-01-01

    We report a widely tunable, narrow linewidth, pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser. By using four dense Bint glass prisms as intra-cavity dispersive elements, the output wavelength can be continuously tuned over 675-970 nm and the spectral linewidth is shortened to 0.5nm. The maximum output power of 6.65 W at 780 nm is obtained under 23.4 Wpump power with repetition rate of 5.5 kHz; corresponding to an conversion efficiency of 28.4%. Due to the gain-switching characteristics of the Ti:sapphire laser, the output pulse duration is as short as 17.6ns.%@@ We report a widely tunable,narrow linewidth,pulsed Th:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersive elements,the output wavelength can be continuously tuned over 675-970nm and the spectral linewidth is shortened to 0.5 nm.The maximum output power of 6.65 W at 780 run is obtained under 23.4 W pump power with repetition rate of 5.5 kHz,corresponding to an conversion efficiency of 28.4%.Due to the gain-switching characteristics of the Ti:sapphire laser,the output pulse duration is as short as 17.6ns.

  19. Idler-resonant intracavity KTA-based OPO pumped by a dual-loss modulated-Q-switched-laser with AOM and Cr4+:YAG

    Science.gov (United States)

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao

    2017-06-01

    An idler-resonant KTiOAsO4 (KTA)-based intracavity optical parametric oscillator (IOPO) pumped by a dual-loss-modulated Q-switched laser with an acousto-optic modulator (AOM) and a Cr4+:YAG saturable absorber (Cr4+:YAG-SA) has been presented. By utilizing a type-II non-critically phase-matched KTA crystal, signal wave at 1535 nm and idler wave at 3467 nm have been generated. Under an incident pump power of 18.3 W, maximum output powers of 615 mW for signal wave and 228 mW for idler wave were obtained at an AOM modulation rate of 10 kHz, corresponding to a whole optical-to-optical conversion efficiency of 4.6%. The shortest pulse widths of signal and idler wave were measured to be 898 ps and 2.9 ns, corresponding to the highest peak powers of 68.4 and 7.9 kW, respectively. In comparison with IOPO pumped by a singly Q-switched laser with an AOM, the IOPO pumped by a doubly Q-switched laser (DIOPO) with an AOM and a Cr4+:YAG-SA can generate signal wave and idler wave with shorter pulse width and higher peak power. By considering the spatial Gaussian distribution of intracavity photon density, a set of coupled rate equations for the idler-resonant DIOPO were built for the first time to the best of our knowledge. The simulation results agreed well with the experimental results.

  20. High power ferrite microwave switch

    Science.gov (United States)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  1. 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: xi.zeng@csem.ch, E-mail: dmitri.boiko@csem.ch; Stadelmann, T.; Grossmann, S.; Hoogerwerf, A. C.; Boïko, D. L., E-mail: xi.zeng@csem.ch, E-mail: dmitri.boiko@csem.ch [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)

    2015-02-16

    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.

  2. Precise calculation of the KTP crystal used as both an intracavity electro-optic Q-switch and a second harmonic generator

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Jianquan Yao; Degang Xu; Pu Zhao; Peng Wang

    2006-01-01

    @@ A method of precisely calculating the external applied voltage and the optimum type-Ⅱ phase matching angles for KTP crystal, which is used as both an intracavity electro-optic (EO) Q-switch and a frequency doubler, is presented. The effective EO coefficient along the phase-matching direction is defined to calculate the half-wave voltage and the quarter-wave voltage, and the precise calculation for the phase matching angles in the condition of KTP crystal optimum second harmonic phase matching is theoretically realized.

  3. High pulse energy passive Q-switching of a diode-pumped Tm:YLF laser by Cr:ZnSe

    Science.gov (United States)

    Korenfeld, Arik; Sebbag, Daniel; Ben-Ami, Udi; Shalom, Eran; Marcus, Gilad; Noach, Salman

    2015-04-01

    A passively Q-switched diode-pumped Tm:YLF laser with polycrystalline Cr:ZnSe as the saturable absorber is demonstrated for the first time, to the best of our knowledge. By using saturable absorbers with different initial transmission, the maximum pulse energy reached 4.22 mJ with peak power of 162.3 kW for a pulse duration of 26 ns. The maximum output average power amounted to 2.2 W. These results constitute significant improvement from the highest average power, pulse energy and peak power results for the PQS Tm:YLF laser to date.

  4. Lean-Burn Stationary Natural Gas Reciprocating Engine Operation with a Prototype Miniature Diode Side Pumped Passively Q-switched Laser Spark Plug

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, D.L.; Woodruff, S.D.; McMillian, M.H.; Richardson, S.W.; Gautam, Mridul

    2008-04-01

    To meet the ignition system needs of large bore lean burn stationary natural gas engines a laser diode side pumped passively Q-switched laser igniter was developed and used to ignite lean mixtures in a single cylinder research engine. The laser design was produced from previous work. The in-cylinder conditions and exhaust emissions produced by the miniaturized laser were compared to that produced by a laboratory scale commercial laser system used in prior engine testing. The miniaturized laser design as well as the combustion and emissions data for both laser systems was compared and discussed. It was determined that the two laser systems produced virtually identical combustion and emissions data.

  5. Experiment Study of Dual Wavelength and Dual Pulse Q-switched Intracavity Frequency Doubling of a Tunable Cr:LiSAF Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Changshui; WANG Peilin; XIE Jianping; SHI Dufang; SHA Xianwu; HE Yulong

    2001-01-01

    In this paper, a flashlamp-pumped Q-switched Cr: LiSAF laser system with intracavity frequency doubling is designed to obtain dual pulse and dual wavelength laser output. The behaviors of second harmonic output of dual pulse and dual wavelength are studied experimentally. Good results are obtained in experiments: the output energy of each second harmonic pulse a round 448.1 nm is 10.2 mJ, the dual pulse time interval can be tuned widely, and the tunable range of each second harmonic wavelength is 448.1 to 465 nm.

  6. Successful Treatment of Tattoo-Induced Pseudolymphoma with Sequential Ablative Fractional Resurfacing Followed by Q-Switched Nd: YAG 532 nm Laser.

    Science.gov (United States)

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

    2013-10-01

    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.

  7. High power neutron production targets

    Energy Technology Data Exchange (ETDEWEB)

    Wender, S. [Los Alamos National Lab., NM (United States)

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  8. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  9. The Effect of Q-Switched Nd:YAG 1064 nm/532 nm Laser in the Treatment of Onychomycosis In Vivo

    Directory of Open Access Journals (Sweden)

    Kostas Kalokasidis

    2013-01-01

    Full Text Available In this prospective clinical study, the Q-Switched Nd:YAG 1064 nm/532 nm laser (Light Age, Inc., Somerset, NJ, USA was used on 131 onychomycosis subjects (94 females, 37 males; ages 18 to 68 years. Mycotic cultures were taken and fungus types were detected. The laser protocol included two sessions with a one-month interval. Treatment duration was approximately 15 minutes per session and patients were observed over a 3-month time period. Laser fluencies of 14 J/cm2 were applied at 9 billionths of a second pulse duration and at 5 Hz frequency. Follow-up was performed at 3 months with mycological cultures. Before and after digital photographs were taken. Adverse effects were recorded and all participants completed “self-evaluation questionnaires” rating their level of satisfaction. All subjects were well satisfied with the treatments, there were no noticeable side effects, and no significant differences were found treating men versus women. At the 3-month follow-up 95.42% of the patients were laboratory mycologically cured of fungal infection. This clinical study demonstrates that fungal nail infections can be effectively and safely treated with Q-Switched Nd:YAG 1064 nm/532 nm laser. It can also be combined with systemic oral antifungals providing more limited treatment time.

  10. Study of passive Q-switching for flash-lamp-pumped 1.34-μm Nd:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    Peng Li; Yufei Li; Yuming Sun; Xueyuan Hou; Huaijin Zhang; Jiyang Wang

    2006-01-01

    The static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4 × 4 × 25 (mm)) at 1.34μm pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T = 30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J,and the corresponding electric-optical conversion efficiency is 0.42%. The Q-switched output of lasers with the output wavelength ranging from 1.3 to 1.6 μm can be realized by using Co2+ :LaMgAl11O19 (Co:LMA)as saturable absorber. A flash-lamp-pumped, passively Q-switched Nd:GdVO4 laser with Co:LMA as saturable absorber is demonstrated in plano-concave laser cavity. With the cavity length of 16.3 cm and pump energy of 19.8 J, the single-pulse output energy, pulse width, and peak power are obtained to be 4m J, 80 ns, and 5 × 104 W, respectively.

  11. The evolution of melasma therapy: targeting melanosomes using low-fluence Q-switched neodymium-doped yttrium aluminium garnet lasers.

    Science.gov (United States)

    Kauvar, Arielle N B

    2012-06-01

    Melasma is an acquired disorder of pigmentation that commonly affects women with phototypes III-V, and it has a negative impact on the quality of life in affected individuals. It presents clinically as symmetric tan or brown patches on the face, most often involving the forehead, cheeks, perioral region, and periorbital region. On histologic examination, there is increased melanin in the epidermis and/or an increased number of melanosomes in the dermis, with a normal number of highly melanized and dendritic melanocytes. The mainstay of treatment is the use of sunscreen along with topical medications that suppress melanogenesis. Clearance is usually incomplete and recurrences or exacerbations are frequent, probably because of the poor efficacy in clearing dermal melanosomes. Treatment with high-energy pigment-specific lasers, ablative resurfacing lasers, and fractional lasers results in an unacceptably high rate of postinflammatory hyper- and hypopigmentation and rebound melasma. Recently, promising results have been achieved with low-fluence Q-switched neodymium-doped yttrium aluminium garnet laser treatment, which can selectively target dermal melanosomes without producing inflammation or epidermal damage, in all skin phototypes. This article reviews the current treatment modalities for melasma, the rationale for using and the clinical results of combination therapy with low-fluence Q-switched neodymium-doped yttrium aluminium garnet lasers.

  12. High performance of a passively Q-switched mid-infrared laser with Bisub>2sub>Tesub>3sub>/graphene composite SA.

    Science.gov (United States)

    You, Zhenyu; Sun, Yijian; Sun, Dunlu; Zhu, Zaojie; Wang, Yan; Li, Jianfu; Tu, Chaoyang; Xu, Jinlong

    2017-02-15

    We report passively Q-switched ∼2 and ∼3  μm mid-infrared (MIR) solid-state lasers with a self-assembly solvothermal-synthesized Bisub>2sub>Tesub>3sub>/graphene heterostructure saturable absorber (SA) for the first time. Based on the oxidation resistance and high thermal conductivity of graphene, and large modulation depth of Bisub>2sub>Tesub>3sub> nanosheets, two high-performance Q-switching lasers were realized. One is a Tm:YAP laser with a maximum average output power of 2.34 W and a pulse width of 238 ns at ∼2  μm. The corresponding maximum pulse peak power was 91 W, which was much improved in comparison with the pure graphene-based Tm laser. The other one is an Er:YSGG laser producing a pulse width of 243 ns, which is the shortest among the 2D SAs-based ∼3  μm solid-state lasers, as far as we know. Our results indicate that such a composite Bisub>2sub>Tesub>3sub>/graphene material is a promising SA for generating high-performance mid-infrared pulse lasers.

  13. Experimental investigation of the spectro-temporal dynamics of the light pulses of Q-switched Nd:YAG lasers and nanosecond optical parametric oscillators

    Science.gov (United States)

    Anstett, G.; Wallenstein, R.

    2004-11-01

    We report an experimental investigation of the spectro-temporal dynamics of the pulse formation in Q-switched Nd:YAG lasers and in nanosecond optical parametric oscillators (OPOs). The temporal evolution of the spectral intensity distribution of the light pulses was measured with a 1-m Czerny Turner spectrometer in combination with a fast streak camera. This detection system allows the analysis of temporal changes in the spectrum of single nanosecond pulses. The measurements were performed for a flashlamp-pumped, Q-switched Nd:YAG laser and for an unseeded as well as for a seeded singly-resonant nanosecond OPO. The laser output spectrum varies strongly from pulse to pulse and even within a single pulse due to mode beating. In an unseeded OPO, individual spectral modes start to oscillate statistically from the parametric noise for pump powers close to the OPO threshold. With increasing pump power a strong modulation in the spectral formation of the pulse is observed, resulting from a strong interaction of parametric conversion and back conversion of signal and idler radiation into pump radiation. By means of injection seeding, the starting condition was controlled for a single mode. Due to the seed radiation, the seeded mode starts sooner than the unseeded modes. These are suppressed completely in the case of sufficient seed power and moderate pump power. The observations are in good agreement with results of corresponding numerical simulations.

  14. 一种快速有效的NQR探头恢复方法%NQR Probe Recovery Time Reduction with a Novel Active Q-Switching Circuit

    Institute of Scientific and Technical Information of China (English)

    陈星; 徐更光

    2008-01-01

    介绍了一种用于主动减小NQR探头恢复时间的Q值变换电路,它利用MOEFET控制变Q电路与探头电路的耦合,并通过变压器增加与电感线圈串联的阻抗值以达到改变Q值的目的.此电路不会产生新的振铃也不会对接收NQR的分辨率造成损失.实验结果表明,电路能有效缩短探头的恢复时间,同时还可以提高信噪比.%An active Q-switching circuit using a transformer is described for reducing the recovery time of NQR probes. A MOSFET was used to control the coupling and decoupling states of the Q-switching circuit to the probe so that it did not operate during the reception of NQR signals. The performance of the circuits was demonstrated by experimental results. It was shown that the circuit did not create new ringing, and caused no loss in sensitivity.

  15. Comparison of Q-switched Nd:YAG laser alone versus its combination with ultrapulse CO2 laser for the treatment of black tattoo.

    Science.gov (United States)

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

    2017-10-01

    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 CO2 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 CO2 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 effect profile of both the groups. For refractory professional tattoos, combination of ultrapulse CO2 laser and QS Nd:YAG laser is superior to QS Nd:YAG laser alone.

  16. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    Science.gov (United States)

    Li, Chao-yu; Dong, Jun

    2016-08-01

    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  17. Linearly polarized pumped passively Q-switched Nd:YVO4 microchip laser for Ince-Gaussian laser modes with controllable orientations

    Science.gov (United States)

    He, Hong-Sen; Zhang, Ming-Ming; Dong, Jun; Ueda, Ken-Ichi

    2016-12-01

    A tilted, linearly polarized laser diode end-pumped Cr4+:YAG passively Q-switched a-cut Nd:YVO4 microchip laser for generating numerous Ince-Gaussian (IG) laser modes with controllable orientations has been demonstrated by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The same IG laser mode with different orientations has been achieved with the same absorbed pump power in a passively Q-switched Nd:YVO4 microchip laser under linearly polarized pumping when the incident pump power and the crystalline orientation of an a-cut Nd:YVO4 crystal are both properly selected. The significant improvement of pulsed laser performance of controllable IG modes has been achieved by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The maximum pulse energy is obtained along the a-axis of an a-cut Nd:YVO4 crystal and the highest peak power is achieved along the c-axis of an a-cut Nd:YVO4 crystal, respectively, which has potential applications on quantum computation and optical manipulation. The generation of controllable IG laser modes in microchip lasers under linearly polarized pumping provides a convenient and universal way to control IG laser mode numbers with anisotropic crystal as a gain medium.

  18. Tattoo removal in micropigs with low-energy pulses from a Q-switched Nd:YAG laser at 1064 nm

    Science.gov (United States)

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

    2001-05-01

    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.

  19. 室温6.11 mJ脉冲LD单端抽运Tm:YAG调Q激光器%6.11 mJ Q-switched Tm:YAG laser end pumped by pulse laser diode at room temperature

    Institute of Scientific and Technical Information of China (English)

    金光勇; 宋雪迪; 吴春婷; 陈薪羽; 于凯

    2014-01-01

    由于2μm波段激光处于大气的窗口上,并且对人眼安全,因而在测风领域具有潜在的应用价值。该波段的激光器可以作为相干多普勒测风雷达和差分吸收雷达的光源。为了进行相干多普勒测风雷达光源的研究,报道了一种脉冲激光二级管(LD)单端抽运Tm:YAG调Q激光器。在实验中,采用L型平凹腔结构,利用声光Q开关实现大能量的激光输出。该激光器输出的激光中心波长为2014.9 nm,在重复频率为100 Hz情况下,调Q后获得最大单脉冲能量为6.11 mJ,激光脉冲宽度为324.7 ns,斜率效率为13.56%的激光输出。输出的脉冲激光的光束质量M2在x方向上为1.31,y方向上为1.35。%The 2 μm laser is in the atmosphere window and the eye -safety wavelength regions. Therefore, it is expected to have potential application in wide range of fields. The lasers can be a light source of Coherent Doppler Wind Lidars and Differential Absorption Lidars. In order to develop a laser light source of Coherent Doppler Wind Lidars, a pulse LD end pumped Q-switched Tm:YAG laser was developed by using a plano-concave cavity with a acousto-optical (AO) Q-switch. The center wavelength of the output laser was measured to be 2 014.9 nm. In the repetition frequency of 100 Hz, a maximum single energy of 6.11 mJ after Q-switching operation and the narrowest pulse width of 324.7 ns were achieved at room temperature, whose slop efficiency was 13.56%. The M2x was 1.31 and the M2y was 1.35.

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

    CSIR Research Space (South Africa)

    Botha, RC

    2013-03-01

    Full Text Available Stellenbosch University, P/Bag X1, Matieland 7602, South Africa 3National Laser Centre, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa 4Physics Department, Carl von Ossietzky University, Oldenburg 26111, Germany 5...-shifted to the 1.5 μm region, which is useful for applications requiring eye-safe operation at high powers, such as Lidar and free-space optical com- munication [1]. Furthermore, 1314.0 nm (specifically the 657.0 nm harmonic) is required to probe the relevant...

  1. Large-energy, narrow-bandwidth laser pulse at 1645 nm in a diode-pumped Er:YAG solid-state laser passively Q-switched by a monolayer graphene saturable absorber.

    Science.gov (United States)

    Zhou, Rong; Tang, Pinghua; Chen, Yu; Chen, Shuqing; Zhao, Chujun; Zhang, Han; Wen, Shuangchun

    2014-01-10

    Nonlinear transmission parameters of monolayer graphene at 1645 nm were obtained. Based on the monolayer graphene saturable absorber, a 1532 nm LD pumped 1645 nm passively Q-switched Er:YAG laser was demonstrated. Under the pump power of 20.8 W, a 1645 nm Q-switched pulse with FWHM of 0.13 nm (without the use of etalon) and energy of 13.5 μJ per pulse can be obtained. To the best of our knowledge, this is the highest pulse energy for graphene-based passively Q-switched Er:YAG laseroperating at 1645 nm, suggesting the potentials of graphene materials for high-energy solid-state laser applications.

  2. The JLab high power ERL light source

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Neil; C. Behre; S.V. Benson; M. Bevins; G. Biallas; J. Boyce; J. Coleman; L.A. Dillon-Townes; D. Douglas; H.F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; M.J. Kelley; L. Merminga; J. Mammosser; W. Moore; N. Nishimori; E. Pozdeyev; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; C. Tennant; R. Walker; G.P. Williams and S. Zhang

    2005-03-19

    concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.

  3. High-power pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Holzrichter, J.F.

    1980-04-02

    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

  4. Stable kilo-hertz electro-optically Q-switched Tm,Ho:YAP laser at room temperature

    Science.gov (United States)

    Liu, C.; Zhao, S.; Li, Y.; Yang, K.; Li, M.; Li, G.; Li, D.; Li, T.; Qiao, W.; Feng, T.; Chen, X.; Zheng, L.; Su, L.; Xu, J.

    2016-07-01

    A diode-pumped Tm,Ho:YAP laser utilizing a self-made LiNbO3 (LN) electro-optically modulator (EOM) at room temperature is demonstrated for the first time. A minimum pulse duration of 107.4 ns was obtained at a pulse repetition rate (PRR) of 200 Hz, giving a maximum single pulse energy of 1.65 mJ. At a PRR of 1 kHz, pulse duration of 145.8 ns was achieved under the absorbed pump power of 7.4 W, corresponding to a maximum single pulse energy of 0.546 mJ, and the pulse to pulse amplitude instabilities were measured to be about 4.6% and 5.83% for PRRs of 200 Hz and 1 kHz, respectively.

  5. Threshold characteristic of intracavity optical parametric oscillator pumped by all-solid-state Q-switched laser

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Degang Xu; Yizhong Yu; Wuqi Wen; Xifu Li; Jianquan Yao

    2008-01-01

    We derive the threshold pump intensity for a singly resonant intracavity optical parametric oscillator (IOPO)based on a temporal coupled field model.Particular attention is Paid to the dependence of the intracavity singly resonant OPO(SRO)threshold intensity on the signal wave output coupling.Meanwhile,a Nd:YAG laser pumped KTiOPO4(KTP)IOPO for eye-safe laser output is studied experimentally.The experiment is performed with four signal wave output reflectivities of 60%,70%,80%,and 90%,respectively.The measured values are in good agreement with the theoretical results.With an output coupler reflectivity of 80%,a peak power of 70 kW at 1572 nm has been obtained at a repetition rate of 3.5 kHz.The pulse width is 4.9 ns.Such investigation is helpful to identifying suitable operational regime of low pump intensity.

  6. 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

    2013-01-01

    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.

  7. Novel technique to treat melasma in Chinese: The combination of 2940-nm fractional Er:YAG and 1064-nm Q-switched Nd:YAG laser.

    Science.gov (United States)

    Tian, Wei Cheng Brian Anthony

    2016-01-01

    Melasma is one of the most common pigmented lesions in Chinese women. Although topical therapies are the mainstay treatment, lasers are being used increasingly to treat pigmented lesions. Laser treatment of melasma is however still controversial. This is because lasers have not been able to produce complete clearance of melasma and recurrence rates are high. Laser treatments also cause complications such as hypopigmentation and post-inflammatory hyperpigmentation. In this article, we report on a novel technique using a combination of fractional 2940-nm Er:YAG and 1064-nm Q-switched Nd:YAG lasers. We achieved a rapid improvement in two cases of melasma in Chinese type III skin. The improvement was seen rapidly within a month of treatment. Follow-up at 6 months showed sustained results with no complications. This novel technique is able to safely confer excellent and sustained clearance within a short treatment time.

  8. Modeling of the Co2+saturable absorber Q-switch for the Er:Yb:glass laser (1.534 um)

    Science.gov (United States)

    Gruber, John B.; Kennedy, Ann W.; Zandi, Bahram; Hutchinson, James A.

    2000-03-01

    We have modeled the passive Q-switch performance of divalent cobalt and its spectroscopic parameters in various host media for the Er:Yb:Glass laser that operates near 1.534 micrometers . Our method involves the use of rate equations that assume a three-level gain medium and a four-level absorber medium including excited-state absorption. Numerical integration techniques are used where analytical functions are unobtainable to describe the dynamics within the systems that we have examined. Input into the rate equations is obtained from experimental data that include Co2+ ion concentrations, cross-sections, and lifetimes obtained by time-resolved spectroscopy. The calculated laser output in terms of pulse energies and pulsewidths in ns is compared with experimental results based on different Co2+ absorber host matricies and different cavity designs.

  9. Violet to Infrared Multiwavelength Generation in Periodically Poled Lithium Niobate Pumped by a Q-Switched Nd:YVO4 Laser

    Institute of Scientific and Technical Information of China (English)

    许祖彦; 梁晓燕; 李健; 姚爱云; 林学春; 崔大复; 吴令安

    2002-01-01

    Six output wavelengths from violet to infrared have been observed simultaneously from an all-solid-state laser pumped optical parametric oscillator in a periodically poled lithium niobate crystal. The output wavelengths can be tuned by varying the quasi-phase matched period and/or temperature. The pump laser is a diode-pumped passive Q-switched Nd:YVO4 laser operated at 1064nm. Using a crystal with a 29.9μm grating period, we measured six wavelengths at 448, 515, 532, 630, 773 and 1546nm and obtained efficient output. We explain the multiwavelength generation by multiwave coupling theory. This phenomenon may have novel applications in photonic devices.

  10. Influence of focal point properties on energy transfer and plasma evolution during laser ignition process with a passively q-switched laser.

    Science.gov (United States)

    Bärwinkel, Mark; Lorenz, Sebastian; Stäglich, Robert; Brüggemann, Dieter

    2016-07-11

    Miniaturized passively q-switched laser ignition systems are a promising alternative to conventional ignition sources to ensure a reliable ignition under difficult conditions. In this study the influences of focal point properties on energy transfer from laser to plasma as well as plasma formation and propagation are investigated as the first steps of the laser induced ignition process. Maximum fluence and fluence volume are introduced to characterize focal point properties for varying laser pulse energies and focusing configurations. The results show that the transferred laser energy increases with increasing maximum fluence. During laser emission plasma propagates along the beam path of the focused laser beam. Rising maximum fluence results in increased plasma volume, but expansion saturates when fluence volume reaches its maximum.

  11. Paradoxical darkening of unperceived tattoo ink after relatively low fluence from a Q-switched Nd:YAG (1064-nm) laser in the course of treatment for melasma.

    Science.gov (United States)

    Chung, W K; Yang, J H; Lee, D W; Chang, S E; Lee, M W; Choi, J H; Moon, K C

    2009-12-01

    Although Q-switched (QS) lasers are the mainstay of modern tattoo removal, paradoxical darkening of tattoo ink may occur. This darkening of tattoo ink is dependent on laser wavelength, pulse duration and fluence, with high-energy, nanosecond-pulsed lasers more prone to induce tattoo-ink darkening. Laser toning, consisting of multiple-passed QS neodymium:yttrium-aluminum-garnet (Nd:YAG), 1064-nm laser treatment with low fluence, short pulse duration (hair, eyebrows or eyelashes, but this phenomenon is reversible. A more problematic error is caused by treatment of eyeliner or eyebrow tattoos. We report a patient who experienced changes in unperceived, skin-coloured tattoos, turning them blue after QS Nd:YAG laser treatment of melasma.

  12. Numerical modeling of the phase-conjugate laser with an intra-cavity stimulated Brillouin scattering mirror: Q-switching mode

    Science.gov (United States)

    Yashkir, Yuri

    2006-04-01

    We present a new computer numerical model of the phase-conjugate laser, utilizing an intra-cavity Stimulated Brillouin Scattering (SBS) element. The modelled laser system includes the active laser crystal which is placed between the output coupler mirror and a stimulated Brillouin scattering cell. The numerical model includes a set of rate equations for the active crystal inverse population, and for the photon density inside the laser cavity. The SBS backscattering model is based on a reduced set of coupled equations for electromagnetic fields for two waves (a pump wave and an SBS wave) propagating in opposite directions. The numerical integration of the set of equations simulates in detail the temporal dynamics of the laser. A wide range of realistic system parameters was numerically investigated. Different laser regimes (from a quasi -CW mode to a Q-switched mode) were numerically tested. The method of numerical modelling of such laser system can be efficiently used for an optimal laser design.

  13. High-speed cutting of thin materials with a Q-switched laser in a water-jet versus conventional laser cutting with a free running laser

    Science.gov (United States)

    Wagner, Frank R.; Boillat, Christophe; Buchilly, Jean-Marie; Spiegel, Akos; Vago, Nandor; Richerzhagen, Bernold

    2003-07-01

    Cutting of thin material, c.f. stencils, stents and thin wafers, is an important market for laser machining. Traditionally this task is performed using flash-lamp pumped, free-running Nd:YAG lasers. Using the water-jet guided laser technology, we experienced that the use of Q-switched lasers leads to superior results while cutting a variety of thin materials. In this technique, the laser is conducted to the work piece by total internal reflection in a thin stable water-jet, comparable to the core of an optical fiber. Utilizing this system, we obtain burr-free, slightly tapered cuts at the same speed as the classical laser cutting and without distinguishable heat affected zone. The main difference is, except the water-jet usage, the pulse duration which is approximately 400 ns instead of 20 to 200 μs in the case of free running lasers. Up to 40'000 high quality apertures per hour can be achieved in stencil mask cutting with the new system. We will compare qualitatively the two possibilities: conventional laser cutting with free-running lasers and water-jet guided laser cutting with Q-switched lasers. The results will be discussed in terms of the different physical effects involved in the material removal upon both methods. In particular the importance of molten material expulsion by the water-jet will be pointed out and compared to the action of the assist-gas. The mentioned effects show that the combination of short pulse laser and water-jet will be beneficial for the production of a wide range of precision parts.

  14. Q-Switched 2.94-microm Er:YAG laser trephination with convergent and divergent cut angles for penetrating keratoplasty.

    Science.gov (United States)

    De Souza, Renate Ferreira; Seitz, Berthold; Langenbucher, Achim; Hofmann-Rummelt, Carmen; Schlötzer-Schrehardt, Ursula; Viestenz, Anja; Küchle, Michael; Naumann, Gottfried O H

    2003-08-01

    To study the morphologic properties of perpendicular (P), convergent (C), and divergent (D) cut angles using different speeds of rotations during donor and recipient nonmechanical trephination for experimental penetrating keratoplasty. With a Q-switched 2.94-microm Er:YAG laser corneal trephination was performed in 150 enucleated porcine eyes using ceramic open masks with 8 "orientation teeth/notches" and an automated globe rotation device allowing different cut angles [0 degree (P), 10 and 20 degrees (C and D)] toward the optical axis and variation of the rotation speed [3, 7, and 11 rotations per minute (rpm)]. The regularity of the cut (I, regular; II, slightly irregular; III, irregular) was assessed by light microscopy. The area of thermal damage and the number and size of "spikes" in the stroma at the superficial, intermediate and deep level of the excision were analyzed using digital images and the Optimas image processing software. The regularity of the cut was classified as I in 42%/22% of donor/recipient and as II in 41%/56%, respectively. The thermal damage was least expressed with D20 degree cut angle and donor mask (P trephination, the thermal damage at the deep level was greatest with 7 rpm (P trephination with appropriate settings results in low thermal damage zones at the cut margin. Different cut angles and speeds of trephination may affect the cut performance and quality of the excision. In our study, low rotation speed and divergent donor cut angles showed the best results. The cut quality and the small thermal damage with the Q-switched 2.94-microm Er:YAG laser seem to be tolerable for corneal trephination. Therefore, this modality may be a low-cost, easy-to-handle alternative for nonmechanical corneal transplantation in humans.

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

    Science.gov (United States)

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

    2015-10-01

    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.

  16. Efficacy of the q-switched neodymium: Yttrium aluminum garnet laser in the treatment of blue-black amateur and professional tattoos

    Directory of Open Access Journals (Sweden)

    Chembolli Lakshmi

    2015-01-01

    Full Text Available Background: 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. Aim: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

  17. Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

    Science.gov (United States)

    Lakshmi, Chembolli; Krishnaswamy, Gayathri

    2015-01-01

    Background: 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. Aim: 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. Materials and Methods: 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/cm2. 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. Results: 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. Conclusion: 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. PMID:26677271

  18. 连续侧面泵浦Nd:YAG陶瓷激光器被动调Q研究%Study on Side Pumped Nd: YAG Ceramic Laser Passively Q-switched

    Institute of Scientific and Technical Information of China (English)

    吴昊; 李洪祚; 王一帆; 刘瑞; 范英杰; 陈薪羽

    2012-01-01

    对比研究了808 nm激光二极管列阵侧面泵浦Nd:YAG陶瓷与Nd:YAG单晶激光器在连续和被动调Q运转下的激光输出特性.对于Nd:YAG陶瓷激光器,在145 W泵浦功率,平平谐振腔20%输出耦合镜透过率时,获得最大44.28W的1 064 nm连续激光输出,光-光转化效率和斜效率分别为30.5%和38.2%.谐振腔中插入初始透过率87.89%的Cr4+:YAG晶体作为被动调Q开关,在124w泵浦功率下获得10.03 kHz重复频率,4.62W平均功率,5.54 kW峰值功率的准连续激光输出.同样实验条件下利用相同尺寸和掺杂浓度的Nd:YAG单晶进行对比,结果表明Nd:YAG陶瓷在高功率泵浦下具有广阔的应用前景.%Abstract; The continuous wave and passively Q-switched output performance of 808 nm laser diode array side pumped Nd: YAG ceramic and Nd: YAG single crystal are studied. In the condition of 145 W pump power and 20% output coupler transmission of a plano-plano resonator, the Nd: YAG ceramic obtains a continuous wave output power of 44. 28 W at 1 064 nm, the optical-to-optical conversion efficiency is 30. 5% , the slope efficiency is 38. 2% . In the same experimental condition, using Cr4+: YAG as the passive Q-switcher, the 10. 03 kHz quasi-continuous laser is obtained when the original transmission ratio is 87. 89% , the average power is 4. 62 W and the peak power is 5. 54 kW. Compared to the same size and doping concentration of Nd: YAG single crystal in the same experimental condition, the result shows that Nd: YAG ceramic laser has a widely application in high power.

  19. Ablation of porcine ligamentum flavum with Ho:YAG, q-switched Ho:YAG, and quadrupled Nd:YAG lasers.

    Science.gov (United States)

    Johnson, Matt R; Codd, Patrick J; Hill, Westin M; Boettcher, Tara

    2015-12-01

    Ligamentum flavum (LF) is a tough, rubbery connective tissue providing a portion of the ligamentous stability to the spinal column, and in its hypertrophied state forms a significant compressive pathology in degenerative spinal stenosis. The interaction of lasers and this biological tissue have not been thoroughly studied. Technological advances improving endoscopic surgical access to the spinal canal makes selective removal of LF using small, flexible tools such as laser-coupled fiber optics increasingly attractive for treatment of debilitating spinal stenosis. Testing was performed to assess the effect of Ho:YAG, Q-switched Ho:YAG, and frequency quadrupled Nd:YAG lasers on samples of porcine LF. The objective was to evaluate the suitability of these lasers for surgical removal of LF. LF was resected from porcine spine within 2 hours of sacrifice and stored in saline until immediately prior to laser irradiation, which occurred within an additional 2 hours. The optical absorbance of a sample was measured over the spectral band from 190 to 2,360 nm both before and after dehydration. For the experiments using the Ho:YAG (λ = 2,080 nm, tp  = 140 µs, FWHM) and Q-Switched Ho:YAG (λ = 2,080 nm, tp  = 260 ns, FWHM) lasers, energy was delivered to the LF through a laser-fiber optic with 600 µm core and NA = 0.39. For the experiment using the frequency quadrupled Nd:YAG laser (λ = 266 nm, tp  = 5 ns FWHM), rather than applying the laser energy through a laser-fiber, the energy was focused through an aperture and lens directly onto the LF. Five experiments were conducted to evaluate the effect of the given lasers on LF. First, using the Ho:YAG laser, the single-pulse laser-hole depth versus laser fluence was measured with the laser-fiber in direct contact with the LF (1 g force) and with a standoff distance of 1 mm between the laser-fiber face and the LF. Second, with the LF remaining in situ and the spine bisected

  20. Optics assembly for high power laser tools

    Science.gov (United States)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  1. Optics assembly for high power laser tools

    Energy Technology Data Exchange (ETDEWEB)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  2. Photonic microwave generation with high-power photodiodes

    CERN Document Server

    Fortier, Tara M; Hati, Archita; Nelson, Craig; Taylor, Jennifer A; Fu, Yang; Campbell, Joe; Diddams, Scott A

    2013-01-01

    We utilize and characterize high-power, high-linearity modified uni-traveling carrier (MUTC) photodiodes for low-phase-noise photonic microwave generation based on optical frequency division. When illuminated with picosecond pulses from a repetition-rate-multiplied gigahertz Ti:sapphire modelocked laser, the photodiodes can achieve 10 GHz signal power of +14 dBm. Using these diodes, a 10 GHz microwave tone is generated with less than 500 attoseconds absolute integrated timing jitter (1 Hz-10 MHz) and a phase noise floor of -177 dBc/Hz. We also characterize the electrical response, amplitude-to-phase conversion, saturation and residual noise of the MUTC photodiodes.

  3. Application possibilities of plasmas generated by high power laser ablation

    OpenAIRE

    Torrisi, L.

    2009-01-01

    High-power pulsed lasers emitting IR and visible radiation with intensities ranging between 10^8 and 10^16 W/cm2, pulse duration from 0.4 to 9 ns and energy from 100 mJ up to 600 J, operating in single mode or in repetition rate, can be employed to produce non-equilibrium plasma in vacuum by irradiating solid targets. Such a laser-produced plasma generates highly charged and high-energy ions of various elements, as well as soft and hard X-ray radiations. Heavy ions with charge state up to 58+...

  4. High power regenerative laser amplifier

    Science.gov (United States)

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

    1994-02-08

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  5. Efficacy of 694-nm fractional Q-switched ruby laser (QSRL) combined with sonophoresis on levorotatory vitamin C for treatment of melasma in Chinese patients.

    Science.gov (United States)

    Zhou, H L; Hu, B; Zhang, C

    2016-07-01

    Melasma is a common acquired and distressing pigmentary disorder presenting to dermatology clinics. It is notably difficult to cure and has a tendency to relapse. The efficacy of classical Q-switched laser in treatment of melasma remains controversial. This study aims to investigate the efficacy and safety of 694-nm fractional QSRL combined with sonophoresis on levorotatory vitamin C for the treatment of melasma patients. Twenty-six patients with melasma were enrolled. Each patient received four to six fractional QSRL treatments at pulse energies of 2.5 to 4 J/cm(2) combined with sonophoresis on levorotatory vitamin C at 2-week intervals. The severity and the area of melasma were assessed by two investigators using the melasma area and severity index (MASI). Side effects were documented. Mean MASI score decreased from 15.51 ± 3.00 before treatment to 10.02 ± 4.39 3 months after the final treatment (P < 0.01). Side effects were few and transient. High-density coverage fractional QSRL combined with sonophoresis on levorotatory vitamin C is safe and effective for the treatment of melasma in Chinese patients.

  6. Multi-wavelength passively Q-switched c-cut Nd:YVO4 self-Raman laser with Cr4+:YAG saturable absorber

    Science.gov (United States)

    Lin, H. Y.; Pan, X.; Huang, X. H.; Xiao, M.; Liu, X.; Sun, D.; Zhu, W. Z.

    2016-06-01

    A multi-wavelength passively Q-switched self-Raman laser with a c-cut Nd:YVO4 both as laser and Raman medium is reported. With the increasing pump power, the multi-wavelength laser including the fundamental line at 1067.4 nm, 1st-Stokes at 1097.9 nm, 2nd-Stokes at 1130.1 nm, and 3rd-Stokes at 1163.6 nm is generated sequentially. At a pump power of 5.0 W, the maximum output power of the four discrete lines are 186.8 mW, 246.5 mW, 158.4 mW and 63.6 mW, with corresponding optical conversion efficiencies of 3.7%, 4.9%, 3.2% and 1.3% respectively. The total stimulated Raman scattering conversion efficiency is 9.4%. To our best knowledge, this is the first report of the 2nd-Stokes at 1130.1 nm and 3rd-Stokes at 1163.6 nm.

  7. 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: yxweng@iphy.ac.cn [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)

    2015-05-15

    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.

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

    Science.gov (United States)

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

    2017-05-01

    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.

  9. A split-face comparison of Q-switched Nd:YAG 1064-nm laser for facial rejuvenation in Nevus of Ota patients.

    Science.gov (United States)

    Yongqian, Cao; Li, Lin; Jianhai, Bi; Ran, Huo; Li, Guo; Hao, Wei; Xining, Wang; Shigang, Xie; Yibing, Wang

    2017-05-01

    We aimed to investigate the efficacy and safety of using the 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (QSNYL) for skin rejuvenation in patients with Nevus of Ota. A retrospective, randomized, split-faced, clinical study was conducted. Twenty-nine patients with unilateral moderate to severe Nevus of Ota were enrolled. The participants completed 3-13 sessions of QSNYL treatments 3-6 months apart. Two independent physicians compared the treated and untreated sides of the face to evaluate the clearance of Nevus of Ota, the wrinkle severity rating scale (WSRS), the global aesthetic improvement scale (GAIS), and adverse event reporting. Patients' satisfaction levels were also considered. Of the 29 patients, 28 (96.6%) achieved nearly complete pigmentation clearance. After an average of 7.76 ± 2.99 sessions, statistically significant improvement in wrinkles and skin texture were observed, compared with the untreated side. The degree of skin rejuvenation was positively correlated with the number of treatment sessions. No clinically adverse effects were observed. Repeated QSNYL treatments not only remove the pigment in Nevus of Ota effectively and safely but also improve facial rejuvenation.

  10. Effect of an epidermal growth factor-containing cream on postinflammatory hyperpigmentation after Q-switched 532-nm neodymium-doped yttrium aluminum garnet laser treatment.

    Science.gov (United States)

    Park, Gyeong-Hun; Rhee, Do Young; Moon, Hye-Rim; Won, Chong Hyun; Lee, Mi Woo; Choi, Jee Ho; Moon, Kee Chan; Chang, Sung Eun

    2015-01-01

    Topical application of epidermal growth factor (EGF) promotes wound healing and may reduce the risk of laser-induced postinflammatory hyperpigmentation (PIH). To investigate the effect of an EGF-containing cream on the incidence of laser-induced PIH. Twenty-five Korean patients with senile lentigines were recruited and underwent 532-nm Q-switched Nd:YAG laser treatment. Postoperatively, patients applied either an EGF-containing cream or a control cream to the laser-treated area. Skin color and transepidermal water loss (TEWL) were measured on Days 0, 3, 7, and 35 using a Mexameter and Tewameter, respectively. The EGF-containing cream resulted in a nonsignificant reduction in the laser-induced increase in TEWL (p = .052 on Day 7) but significantly decreased the melanin index and incidence of PIH on Day 35 (p = .031 and p = .027, respectively). Epidermal growth factor-containing creams may be an effective measure to prevent laser treatment-induced PIH in Asian patients.

  11. A Retrospective Study on the Characteristics of Treating Nevus of Ota by 1064-nm Q-switched Neodymium-doped Yttrium Aluminum Garnet Laser

    Science.gov (United States)

    Liu, Yanting; Zeng, Weihui; Geng, Songmei

    2016-01-01

    Background: The Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser has a significant effect in treating nevus of Ota, but there is lack of a retrospective study about the characteristics of efficacy. Aims and Objectives: To retrospectively analyze the correlation between the clinical characteristics and efficacy, complications, recurrence of QS Nd:YAG laser in treating nevus of Ota. Materials and Methods: One hundred and seventy-one Chinese patients (144 female, 27 male) of nevus of Ota were treated with the 1064-nm QS Nd:YAG laser. All cases were treated with fluencies of 4–8 J/cm2 and a spot size of 2–4 mm. Clinical photographs were taken before every treatment and patients were followed up by their clinicians. Results: One hundred and forty-five patients (84.8%) acquired more than 75% improvement with an average of 4.6 sessions. The treatment effect has no significant correlation with sex (P > 0.05). The blue-black and brown lesions improved more than the light-brown (P nevus of Ota. The efficacy correlated with lesion color, which is meaningful to estimate the prognosis. PMID:27293272

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

    Science.gov (United States)

    Li, Deyong; Li, Yunliang; Li, Hao; Wu, Xianyou; Yu, Qingxu; Weng, Yuxiang

    2015-05-01

    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(-1) as the IR probe. The results demonstrate that this system has a sensitivity of 1 × 10(-4) ΔOD for a single wavelength detection, and 2 × 10(-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.

  13. Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers.

    Science.gov (United States)

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

    2017-08-01

    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.

  14. Thermal and laser properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ for high power dual-wavelength laser.

    Science.gov (United States)

    Wu, K; Hao, L Z; Yu, H H; Wang, Z P; Wang, J Y; Zhang, H J

    2012-03-26

    We measured the thermal properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ (Nd:LuSGG) crystal, including the thermal expansion coefficient, specific heat, and thermal diffusion coefficient. The calculated thermal conductivity is 4.4 W/mK at room temperature. A high-power continuous-wave and passively Q-switched Nd:LuSGG laser was also demonstrated. Continuous-wave output power of 6.96 W is obtained which is the highest power with this material. For the first time to our knowledge, the passively Q-switched Nd:LuSGG laser is reported with the shortest pulse width, largest pulse energy, and highest peak power are achieved to be 5.1 ns, 62.5 μJ, and 12 kW, respectively. By spectral analysis, it has been found that the Nd:LuSGG laser was located at 1059 nm under low pump power, and became dual-wavelength at 1061.5 and 1059 nm when the incident pump power is over 2.27 W. The generating mechanism of dual-wavelength laser is also discussed.

  15. High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    Science.gov (United States)

    Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

    2009-01-01

    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 at NASA Langley Research Center. Such a laser 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 approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

  16. Very High Power THz Radiation Sources

    OpenAIRE

    Carr, G.L.; Martin, M. C.; McKinney, W.R.; Jordan, K.; Neil, G. R.; Williams, G. P.

    2003-01-01

    We report the production of high power (20watts average, ∼ 1 Megawatt peak) broadbandTHz light based on coherent emission fromrelativistic electrons. Such sources areideal for imaging, for high power damagestudies and for studies of non-linearphenomena in this spectral range. Wedescribe the source, presenting theoreticalcalculations and their experimentalverification. For clarity we compare thissource with one based on ultrafast lasertechniques.

  17. Packaging of high power semiconductor lasers

    CERN Document Server

    Liu, Xingsheng; Xiong, Lingling; Liu, Hui

    2014-01-01

    This book introduces high power semiconductor laser packaging design. The characteristics and challenges of the design and various packaging, processing, and testing techniques are detailed by the authors. New technologies, in particular thermal technologies, current applications, and trends in high power semiconductor laser packaging are described at length and assessed.

  18. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  19. High power laser perforating tools and systems

    Science.gov (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

    2014-04-22

    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  20. High-efficiency mid-infrared ZnGeP2 optical parametric oscillator directly pumped by a lamp-pumped, Q-switched CrTmHo:YAG laser

    NARCIS (Netherlands)

    Nieuwenhuis, Albert F.; Lee, Christopher James; van der Slot, Petrus J.M.; Lindsay, I.D.; Gross, P.; Boller, Klaus J.

    2008-01-01

    We report a singly resonant optical parametric oscillator (SRO) based on a ZnGeP2 crystal directly pumped by a lamp-pumped Q-switched CrTmHo:YAG laser. The IR was tunable from 4.7 to 7.8 μm via crystal angle tuning. A maximum optical to optical efficiency of 56% was obtained from the pump (2.09 μm)

  1. Low-power fractional CO₂ laser versus low-fluence Q-switch 1,064 nm Nd:YAG laser for treatment of melasma: a randomized, controlled, split-face study.

    Science.gov (United States)

    Jalaly, Niloofar Y; Valizadeh, Neda; Barikbin, Behrooz; Yousefi, Maryam

    2014-08-01

    Various laser treatments are currently available for melasma but their use remains challenging because of potential side effects. The aim of this randomized controlled study was to compare the efficacy and safety of low-fluence Q-switch 1,064 nm Nd:YAG and low-power fractional CO2 laser using a split-face design. A total of 40 female patients with symmetric melasma were enrolled to the study and each side of their face was randomly allocated to either low-fluence Q-switch 1,064 nm Nd:YAG or low-power fractional CO2 laser. They were treated every 3 weeks for five consecutive sessions and followed for 2 months after the last treatment session. Response to treatment was assessed using the Melanin Index (MI) score, modified Melasma Area and Severity Index (mMASI) score, and a subjective self-assessment method. At the 2-month follow-up visit, both sides of the face had statistically significant reductions in the MI and mMASI scores compared with the first visit (p laser-treated side was significantly more than on the Q-switch 1,064 nm Nd:YAG laser-treated side (p laser treatments. The present study shows that low-power fractional CO2 laser is safe and effective and can be considered as a valuable approach in the treatment of melasma.

  2. A Comparison of Low-Fluence 1064-nm Q-Switched Nd: YAG Laser with Topical 20% Azelaic Acid Cream and their Combination in Melasma in Indian Patients

    Science.gov (United States)

    Bansal, Charu; Naik, Hira; Kar, Hemanta K; Chauhan, Amrita

    2012-01-01

    Background: Melasma is an acquired symmetric hypermelanosis characterised by irregular light to gray-brown macules on sun-exposed skin with a predilection for the cheeks, forehead, upper lip, nose and chin. The management of melasma is challenging and requires meticulous use of available therapeutic options. Aims: To compare the therapeutic efficacy of low-fluence Q-switched Nd: YAG laser (QSNYL) with topical 20% azelaic acid cream and their combination in melasma in three study groups of 20 patients each. Materials and Methods: Sixty Indian patients diagnosed as melasma were included. These patients were randomly divided in three groups (group A = 20 patients of melasma treated with low-fluence QSNYL at weekly intervals, group B = 20 patients of melasma treated with twice daily application of 20% azelaic acid cream and group C = 20 patients of melasma treated with combination of both). Study period was of 12 weeks each. Response to treatment was assessed using melasma area and severity index score. Statistical Analysis: The statistical analysis was done using Chi-square test, paired and unpaired student t-test. Results: Significant improvement was recorded in all the three groups. The improvement was statistically highly significant in Group C as compared to group A (P < 0.001) and group B (P < 0.001). Conclusions: This study shows the efficacy of low-fluence QSNYL, topical 20% azelaic acid cream and their combination in melasma. The combination of low-fluence QSNYL and topical 20% azelaic acid cream yields better results as compared to low-fluence QSNYL and azelaic acid alone. PMID:23378709

  3. Depigmentation with Q-switched Nd:YAG laser in universal vitiligo: a long-term follow-up study of 4 years.

    Science.gov (United States)

    Majid, Imran; Imran, Saher

    2017-05-01

    Q-switched (QS) lasers are used for depigmentation in universal vitiligo, but there is limited data on long-term results after laser treatment. This study was conducted to assess the safety and long-term follow-up results of QS Nd:YAG laser treatment in combination with need-based topical depigmentation therapy for universal vitiligo. A retrospective study was performed on patients with universal vitiligo who had received QS Nd:YAG laser treatment from 2010 to 2013. All patients were contacted and called for follow-up. Patients who reported were assessed clinically and information regarding adverse effects and relapse (repigmentation) in the follow-up period were obtained. Any need for topical depigmenting creams or other interventions and overall satisfaction to treatment were also documented. Records of 34 patients were retrieved, out of whom 28 cases reported for the follow-up visit. Duration of follow-up ranged from 2 to 5 years (mean, 2.78). No long-term adverse effects were reported and the majority of patients were highly satisfied with treatment. Satisfactory results with >90% clearance of pigment was reported by 89.3% (25/28) of patients, out of whom 72% (18/25) had retained the therapeutic effect with the use of sunscreens with/without intermittent topical depigmentation therapies. In seven cases, partial to complete relapse was observed. QS Nd:YAG laser is an effective tool for treating residual pigmentation in universal vitiligo, and the therapeutic effect can be maintained in most cases with regular sunscreen use and need-based topical therapies.

  4. A retrospective study on the characteristics of treating nevus of ota by 1064-nm q-switched neodymium-doped yttrium aluminum garnet laser

    Directory of Open Access Journals (Sweden)

    Yanting Liu

    2016-01-01

    Full Text Available Background: The Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG laser has a significant effect in treating nevus of Ota, but there is lack of a retrospective study about the characteristics of efficacy. Aims and Objectives: To retrospectively analyze the correlation between the clinical characteristics and efficacy, complications, recurrence of QS Nd:YAG laser in treating nevus of Ota. Materials and Methods: One hundred and seventy-one Chinese patients (144 female, 27 male of nevus of Ota were treated with the 1064-nm QS Nd:YAG laser. All cases were treated with fluencies of 4–8 J/cm2 and a spot size of 2–4 mm. Clinical photographs were taken before every treatment and patients were followed up by their clinicians. Results: One hundred and forty-five patients (84.8% acquired more than 75% improvement with an average of 4.6 sessions. The treatment effect has no significant correlation with sex (P > 0.05. The blue-black and brown lesions improved more than the light-brown (P < 0.05. Hyperpigmentation affected two (1.2% of the patients and hypopigmentation affected one patient (0.6%. No other adverse effect was observed. Recurrence was seen in two patients (1.2%. Conclusion: The 1064-nm QS Nd:YAG laser is effective with rare complications and recurrence in the treatment of nevus of Ota. The efficacy correlated with lesion color, which is meaningful to estimate the prognosis.

  5. A comparison of low-fluence 1064-nm Q-switched Nd: YAG laser with topical 20% azelaic acid cream and their combination in melasma in Indian patients

    Directory of Open Access Journals (Sweden)

    Charu Bansal

    2012-01-01

    Full Text Available Background: Melasma is an acquired symmetric hypermelanosis characterised by irregular light to gray-brown macules on sun-exposed skin with a predilection for the cheeks, forehead, upper lip, nose and chin. The management of melasma is challenging and requires meticulous use of available therapeutic options. Aims: To compare the therapeutic efficacy of low-fluence Q-switched Nd: YAG laser (QSNYL with topical 20% azelaic acid cream and their combination in melasma in three study groups of 20 patients each. Materials and Methods: Sixty Indian patients diagnosed as melasma were included. These patients were randomly divided in three groups (group A = 20 patients of melasma treated with low-fluence QSNYL at weekly intervals, group B = 20 patients of melasma treated with twice daily application of 20% azelaic acid cream and group C = 20 patients of melasma treated with combination of both. Study period was of 12 weeks each. Response to treatment was assessed using melasma area and severity index score. Statistical Analysis: The statistical analysis was done using Chi-square test, paired and unpaired student t-test. Results: Significant improvement was recorded in all the three groups. The improvement was statistically highly significant in Group C as compared to group A ( P < 0.001 and group B ( P < 0.001. Conclusions: This study shows the efficacy of low-fluence QSNYL, topical 20% azelaic acid cream and their combination in melasma. The combination of low-fluence QSNYL and topical 20% azelaic acid cream yields better results as compared to low-fluence QSNYL and azelaic acid alone.

  6. A comparative study on efficacy of high and low fluence Q-switched Nd:YAG laser and glycolic acid peel in melasma

    Directory of Open Access Journals (Sweden)

    Hemanta Kumar Kar

    2012-01-01

    Full Text Available Background: Melasma is acquired symmetric hypermelanosis characterized by light-to-deep brown pigmentation over cheeks, forehead, upper lip, and nose. Treatment of this condition is difficult and associated with high recurrence rates. With the advent of newer therapies, there is interest in the use of glycolic acid peels and Q-switched Nd:YAG laser (QSNYL in high and low fluence for this disorder. Aims: To compare the therapeutic efficacy of low fluence QSNYL, high fluence QSNYL, and glycolic acid peel in melasma in three study groups of 25 patients each. Methods: Seventy-five Indian patients diagnosed as melasma were included. These patients were randomly divided in three groups (Group A = 25 patients of melasma treated with low-fluence QSNYL at weekly intervals, Group B = 25 patients of melasma treated with glycolic acid peel at 2 weeks intervals, Group C = 25 patients of melasma treated with high-fluence QSNYL at 2 weeks intervals. Study period and follow-up period was of 12 weeks each. Out of the 75 patients included, 21 patients in Group A, 19 patients in Group B, and 20 patients in Group C completed the study. Response to treatment was assessed using melasma area and severity index score. Results: Significant improvement was recorded in all the three groups. The improvement was statistically highly significant in Group A as compared to Group C (P<0.005, significant in Group A as compared to Group B (P<0.05, and also in Group B when compared to Group C (P<0.05. Low-fluence QSNYL was associated with least side effects. Conclusions: This study shows the efficacy of low-fluence QSNYL and glycolic acid peel in melasma. These could be an effective treatment options compared to conventional methods for the treatment of melasma.

  7. Efficient intracavity frequency doubling of a high-repetition-rate diode-pumped Nd:YAG laser.

    Science.gov (United States)

    Hanson, F; Poirier, P

    1994-10-01

    Efficient operation of a pulsed, high-repetition-rate diode-pumped and intracavity frequency-doubled Nd:YAG laser is reported. A 3-mm-diameter laser rod was side-pumped with a 5-bar stack of high-duty-cycle 1-cm diodearrays. The average Q-switched power at 1.06microum was 3.8 W at 1.33 kH(z), and more than 4 W at 0.532 ,microm wasobtained through intracavity frequency doubling with LiB(3)O(5).

  8. High Power Helicon Plasma Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed work seeks to develop and optimize an electrode-less plasma propulsion system that is based on a high power helicon (HPH) that is being developed...

  9. High Power Helicon Plasma Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new thruster has been conceived and tested that is based on a high power helicon (HPH) plasma wave. In this new method of propulsion, an antenna generates and...

  10. High Power Fiber Laser Test Bed

    Data.gov (United States)

    Federal Laboratory Consortium — This facility, unique within DoD, power-combines numerous cutting-edge fiber-coupled laser diode modules (FCLDM) to integrate pumping of high power rare earth-doped...

  11. Coupling output of multichannel high power microwaves

    Science.gov (United States)

    Li, Guolin; Shu, Ting; Yuan, Chengwei; Zhang, Jun; Yang, Jianhua; Jin, Zhenxing; Yin, Yi; Wu, Dapeng; Zhu, Jun; Ren, Heming; Yang, Jie

    2010-12-01

    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  12. ULTRA HIGH POWER TRANSMISSION LINE TECHNIQUES

    Science.gov (United States)

    The ultra-high power transmission line techniques including both failure mechanisms and component design are discussed. Failures resulting from...a waveguide. In view of the many advantages of the low loss mode in circular waveguide for ultra-high power levels, a mode transducer and a two...percent of the peak power of a standard rectangular wave guide. Water cooling is provided for high average power operation. Analysis of mode sup pression

  13. High Power Performance of Rod Fiber Amplifiers

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Michieletto, Mattia; Kristensen, Torben

    2015-01-01

    An improved version of the DMF rod fiber is tested in a high power setup delivering 360W of stable signal power. Multiple testing degrades the fiber and transverse modal instability threshold from >360W to ~290W.......An improved version of the DMF rod fiber is tested in a high power setup delivering 360W of stable signal power. Multiple testing degrades the fiber and transverse modal instability threshold from >360W to ~290W....

  14. Switching power converters medium and high power

    CERN Document Server

    Neacsu, Dorin O

    2013-01-01

    An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

  15. Plasma relaxation mechanics of pulsed high power microwave surface flashover

    Energy Technology Data Exchange (ETDEWEB)

    Beeson, S.; Dickens, J.; Neuber, A. [Center for Pulsed Power and Power Electronics, Department of Electrical and Computer Engineering and Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States)

    2013-09-15

    Microwave transmission and reflection characteristics of pulsed radio frequency field generated plasmas are elucidated for air, N{sub 2}, and He environments under pressure conditions ranging from 10 to 600 torr. The pulsed, low temperature plasma is generated along the atmospheric side of the dielectric boundary between the source (under vacuum) and the radiating environment with a thickness on the order of 5 mm and a cross sectional area just smaller than that of the waveguide. Utilizing custom multi-standard waveguide couplers and a continuous low power probing source, the scattering parameters were measured before, during, and after the high power microwave pulse with emphasis on the latter. From these scattering parameters, temporal electron density estimations (specifically the longitudinal integral of the density) were calculated using a 1D plane wave-excited model for analysis of the relaxation processes associated. These relaxation characteristics ultimately determine the maximum repetition rate for many pulsed electric field applications and thus are applicable to a much larger scope in the plasma community than just those related to high power microwaves. This manuscript discusses the diagnostic setup for acquiring the power measurements along with a detailed description of the kinematic and chemical behavior of the plasma as it decays down to its undisturbed state under various gas type and pressure conditions.

  16. Uppsala High Power Test Stand for ESS Spoke Cavities

    CERN Document Server

    Yogi, RA; Dancila, D; Gajewski, K; Hermansson, L; Noor, M; Wedberg, R; Santiago-Kern, R; Ekelöf, T; Lofnes, T; Ziemann, V; Goryashko, V; Ruber, R

    2013-01-01

    The European Spallation Source (ESS) is one of the world’s most powerful neutron source. The ESS linac will accelerate 50mA pulse current of protons to 2.5GeV in 2.86 ms long pulses at a repetition rate of 14 Hz. It produces a beam with 5MW average power and 125MW peak power. ESS Spoke Linac consist of 28 superconducting spoke cavities, which will be developed by IPN Orsay, France. These Spoke Cavities will be tested at low power at IPN Orsay and high power testing will be performed in a high power test stand at Uppsala University. The test stand consists of tetrode based RF amplifier chain (352MHz, 350 kW) power and related RF distribution. Outputs of two tetrodes shall be combined with the hybrid coupler to produce 350 kW power. Preamplifier for a tetrode shall be solid state amplifier. As the spoke cavities are superconducting, the test stand also includes horizontal cryostat, Helium liquefier, test bunker etc. The paper describes features of the test stand in details.

  17. Photoinjector RF cavity design for high power CW FEL

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Sergey); Schrage, D. L. (Dale L.); Wood R. L. (Richard L.); Young, L. M. (Lloyd M.); Schultheiss, T. (Thomas); Christina, V.; Rathke, J. (John)

    2002-01-01

    The project is under way to develop a key enabling technology for high-power CW FEL: an RF photoinjector capable of producing continuous average current greater than 100 mA. The specific aim is a 700 MHz pi-mode, normal-conducting RF photoinjector, 3 nC of bunch charge, 100 mA of current (at 33.3-MHz bunch repetition rate) and emittance less than 10 mm-mrad. This level of performance will enable robust 100-kW-class FEL operation with electron beam energy 400 MeV, thereby reducing the size and cost of the FEL. This design is scalable to the MW power level by increasing the electron bunch repetition rate from 33.3 MHz to a higher value. The major challenges are emittance control and high heat flux within the CW 700-MHz RF cavities. Results of RF cavity design and cooling schemes are presented, including both high-velocity water and liquid nitrogen cooling options.

  18. Advances in high power semiconductor diode lasers

    Science.gov (United States)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  19. High Power Diode Lasers Technology and Applications

    CERN Document Server

    Bachmann, Friedrich; Poprawe, Reinhart

    2007-01-01

    In a very comprehensive way this book covers all aspects of high power diode laser technology for materials processing. Basics as well as new application oriented results obtained in a government funded national German research project are described in detail. Along the technological chain after a short introduction in the second chapter diode laser bar technology is discussed regarding structure, manufacturing technology and metrology. The third chapter illuminates all aspects of mounting and cooling, whereas chapter four gives wide spanning details on beam forming, beam guiding and beam combination, which are essential topics for incoherently coupled multi-emitter based high power diode lasers. Metrology, standards and safety aspects are the theme of chapter five. As an outcome of all the knowledge from chapter two to four various system configurations of high power diode lasers are described in chapter six; not only systems focussed on best available beam quality but especially also so called "modular" set...

  20. High Power Co-Axial Coupler

    Energy Technology Data Exchange (ETDEWEB)

    Neubauer, M. [Muons, Inc.; Dudas, A. [Muons, Inc.; Rimmer, Robert A. [JLAB; Guo, Jiquan [JLAB; Williams, R. Scott [JLAB

    2013-12-01

    A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

  1. High-power optics lasers and applications

    CERN Document Server

    Apollonov, Victor V

    2015-01-01

    This book covers the basics, realization and materials for high power laser systems and high power radiation interaction with  matter. The physical and technical fundamentals of high intensity laser optics and adaptive optics and the related physical processes in high intensity laser systems are explained. A main question discussed is: What is power optics? In what way is it different from ordinary optics widely used in cameras, motion-picture projectors, i.e., for everyday use? An undesirable consequence of the thermal deformation of optical elements and surfaces was discovered during studies of the interaction with powerful incident laser radiation. The requirements to the fabrication, performance and quality of optical elements employed within systems for most practical applications are also covered. The high-power laser performance is generally governed by the following: (i) the absorption of incident optical radiation (governed primarily by various absorption mechanisms), (ii) followed by a temperature ...

  2. Study on the Pulse Interval of Passively Q-Switched Laser Pumped by Diode Laser Pulse%脉冲抽运被动调Q激光器脉冲间隔特性研究

    Institute of Scientific and Technical Information of China (English)

    许韬; 金光勇; 于永吉; 陈薪羽; 王超; 吴春婷

    2012-01-01

    采用数值模拟和实验相结合的方法对脉冲激光二极管(LD)抽运Nd:YAG被动调Q激光器输出脉冲间隔特性进行分析.从被动调Q速率方程出发,结合脉冲LD抽运的特点,考虑剩余反转粒子数密度的影响,推导出输出调Q脉冲间隔时间的计算公式.重点分析了抽运脉宽、输出镜反射率、抽运功率和Cr4+:YAG初始透射率对输出脉冲间隔时间的影响.结果表明,数值模拟与实验结果基本吻合.%A passively Q-switched Nd! YAG laser pumped by diode pulse is set up. The characteristics of the laser pulse intervals are analysed by combining numerical simulation and experimental method. Starting with the rate equation of passively Q-switching mode, the Q-switched pulse intervals are formulated in consideration of the feature of diode pulse pumping and the influence of surplus inverse population density. The in fluence of pumping current and pulse width, the reflectivity of output mirror and the initial transmission of Cr4+: YAG on pulse interval time is analysed enphatically. The result indicates that the numerical simulation of pulse interval time coincides with the experimental data.

  3. The therapeutic effect analysis of 1496 cases in the treatment of nevus of Ota by Q-switch Nd:YAG laser%Q开关Nd:YAG激光治疗太田痣1496例疗效分析

    Institute of Scientific and Technical Information of China (English)

    李朝惠; 尹锐; 邓军; 程良金; 黄义森; 杨利

    2011-01-01

    目的:回顾性分析Q开关Nd:YAG激光治疗仪治疗太田痣的疗效和安全性.方法:分析2006年3月~2011年3月笔者科室运用Q开关激光仪治疗1 496例太田痣患者的临床疗效,根据治疗前后照片进行对比分析.结果:1 496例太田痣经4~10次治疗,痊愈1311例,显效132例,有效53例,总有效率为100%.12例出现一过性色素沉着,所有患者均未出现严重不良反应.结论:Q开关Nd:YAG激光治疗太田痣安全、有效,治疗次数与疗效成正比相关,治疗次数越多,效果越好.%Objective To evaluate the clinical effect and safety of nevus of Ota by Q-switch Nd:YAG laser. Methods The clinical data of 1496 cases of nevus of ota treated by Q-switch laser were retrospectively analyzed from March, 2006 to March 2011 in our department. Results 1496 cases of nevus of Ota were treated by 4-10 times,1311 cases were completely cured. 132 cases showed good effect. 53 cases showed effect. All effect rate was 100%.12 cases showed hyperpigmentation There was no severe side effect. Conclusion Q-switched Nd:YAG laser Medlite C6 is effective in treatment of vevus of Ota.Proportional to the treatment number was associated with the efficacy of treatment. The more treatment times can get better effects.

  4. A continuously variable beam-diameter, high-fluence, Q-switched Nd:YAG laser for tattoo removal: comparison of the maximum beam diameter to a standard 4-mm-diameter treatment beam.

    Science.gov (United States)

    Bernstein, Eric F; Civiok, Jennifer M

    2013-12-01

    Laser beam diameter affects the depth of laser penetration. Q-switched lasers tend to have smaller maximum spot sizes than other dermatologic lasers, making beam diameter a potentially more significant factor in treatment outcomes. To compare the clinical effect of using the maximum-size treatment beam available for each delivered fluence during laser tattoo removal to a standard 4-mm-diameter treatment beam. Thirteen tattoos were treated in 12 subjects using a Q-switched Nd:YAG laser equipped with a treatment beam diameter that was adjustable in 1 mm increments and a setting that would enable the maximally achievable diameter ("MAX-ON" setting) with any fluence. Tattoos were randomly bisected and treated on one side with the MAX-ON setting and on the contralateral side with a standard 4-mm-diameter spot ("MAX-OFF" setting). Photographs were taken 8 weeks following each treatment and each half-tattoo was evaluated for clearance on a 10-point scale by physicians blinded to the treatment conditions. Tattoo clearance was greater on the side treated with the MAX-ON setting in a statistically significant manner following the 1st through 4th treatments, with the MAX-OFF treatment site approaching the clearance of the MAX-ON treatment site after the 5th and 6th treatments. This high-energy, Q-switched Nd:YAG laser with a continuously variable spot-size safely and effectively removes tattoos, with greater removal when using a larger spot-size. © 2013 Wiley Periodicals, Inc.

  5. Q开关Nd:YAG激光治疗面部色素增加性病变疗效分析%Efifcacy of the pigmented dermatosis treated with Q-switched Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    严芳; 周炳荣; 卢寅

    2016-01-01

    Objective To observe the clinical effect and side-effect of the pigmented dermatosis is treated by Q-switched Nd:YAG laser. Methods A total of 145 cases were treated with Q-switched Nd:YAG laser. The superifcial pigmented lesions, such as freckle ,cafe-au-lait spots and senile plaques were treated using 532nm wavelength , while the Nevus of Ota and tattoo were treated with 1064nm wavelength. Results All the 145 cases of pigmented disorders obtained good results, especially those with tattoo, freckle, senile plaques. Conclusion The Q-switched Nd:YAG laser has been proven to be effective and safe in the treatment of pigmented dermatosis.%目的:观察Q开关Nd:YAG激光治疗面部色素增加性皮肤病的临床疗效及副反应。方法:使用Q开关Nd:YAG激光治疗145例色素增加性皮肤病患者。雀斑、咖啡斑和脂溢性角化病采用波长532nm,太田痣和文身采用波长l 064nm。结果:145例患者经治疗后,色素性病变逐渐消退,其中文身、雀斑、脂溢性角化病疗效较为显著。结论:Q开关Nd:YAG激光治疗色素增加性皮肤病疗效好,安全有效,是一种无创的治疗方法。

  6. High Power Short Wavelength Laser Development

    Science.gov (United States)

    1977-11-01

    Unlimited güä^äsjäsiiiüüü X NRTC-77-43R P I High Power Short Wavelength Laser Development November 1977 D. B. Cohn and W. B. Lacina...NO NRTC-77-43R, «. TITLE fana »uetjjitj BEFORE COMPLETING FORM CIPIENT’S CATALOO NUMBER KIGH.POWER SHORT WAVELENGTH LASER DEVELOPMENT , 7...fWhtn Data Enterte NRTC-77-43R HIGH POWER SHORT WAVELENGTH LASER DEVELOPMENT ARPA Order Number: Program Code Number: Contract Number: Principal

  7. Diagnostics for High Power Targets and Dumps

    CERN Document Server

    Gschwendtner, E

    2012-01-01

    High power targets are generally used for neutrino, antiproton, neutron and secondary beam production whereas dumps are needed in beam waste management. In order to guarantee an optimized and safe use of these targets and dumps, reliable instrumentation is needed; the diagnostics in high power beams around targets and dumps is reviewed. The suite of beam diagnostics devices used in such extreme environments is discussed, including their role in commissioning and operation. The handling and maintenance of the instrumentation components in high radiation areas is also addressed.

  8. Therapeutic Effect of Q-Switch Ruby Laser on Skin Pigmentary Lesions%Q开关红宝石激光治疗皮肤色素性病变疗效分析

    Institute of Scientific and Technical Information of China (English)

    陈芙莉; 张海荣

    2012-01-01

    目的 观察Q开关红宝石激光治疗太田痣、雀斑、咖啡斑及蓝黑色纹身等不同色素性损害的疗效及安全性.方法 分析2008年6月至2012年5月应用Q开关红宝石激光治疗色素性病变患者3268例的临床疗效,针对不同的病变类型选择采用不同的治疗参数.每个疗程观察4~6个月.根据治疗前后照片进行对比分析.结果 Q开关红宝石激光对雀斑、咖啡斑效果最好,一次治愈率达99.8%;对太田痣、纹身经4~8次治疗也达到满意效果.所有患者均未出现严重不良反应.结论 Q开关红宝石激光治疗色素性病变安全、有效,治疗次数与疗效成正相关.对表皮层色素性病变治疗次数少;对真皮层色素性病变治疗次数越多效果越好.%Objective To observe the therapeutic effect of Q-switched ruby laser on diversified pigmentary disorders. Methods Altogether 3 268 cases of nevus of ota, ephelides, cafe aulait macules and tattoo were treated with Q-switched ruby laser and the effects were retrospectively analyzed from Jun. 2008 to May 2012. The treatment interval lasted for 4-6 months. Results Q-switch ruby laser was most effective in treating ephelides with a cure rate up to 99. 8% after a treatment. It was followed by nevus of ota and tattoo, which were cured after 4-8 treatments. Conclusions Q-switch ruby laser is effective in treating pigmented dermatoses. Treatment frequency is directly proportional to therapeutic efficacy.

  9. Efficacy and safety of fractional Q-switched 1064-nm neodymium-doped yttrium aluminum garnet laser in the treatment of melasma in Chinese patients.

    Science.gov (United States)

    Yue, Baishuang; Yang, Qianli; Xu, Jinhua; Lu, Zhong

    2016-11-01

    Melasma is an acquired disorder of symmetrical hyperpigmentation commonly seen in patients with Fitzpatrick skin types III and IV. Various novel therapeutic modalities have emerged to treat melasma. The large-spot low-fluence QS Nd:YAG laser has been widely used in Asia; however, the modality needs to be optimized because of the high recurrence rate. The objective of this study is to explore the clinical efficacy and safety of fractional-mode (Pixel) Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm laser for treatment of melasma in Chinese patients. Twenty-seven patients were enrolled and completed all the treatment sessions and the 12-week follow-up. All were treated using the fractional-mode Pixel QS Nd:YAG (1064 nm) laser for eight sessions at a 2-3-week interval. Clinical photographs were taken using the Visia skin analysis imaging system. Two blinded assessors evaluated melasma area and severity index (MASI) scores before and 4 weeks after the final session. Melanin index (MI) and erythema index (EI) was measured before each treatment visit and after the final treatment. The degree of pigmentation and erythema was assessed using a tristimulus color analyzer. Physicians' global assessment (PGA) and patients' self-assessment were taken as the subjective assessments. Wilcoxon signed-rank test was performed to evaluate clinical response. Recurrence rate were also evaluated. Mean MASI scores decreased from 12.84 ± 6.89 to 7.29 ± 4.15 after treatment (p = 0.000). Seventy percent of patients got moderate to good improvements after all the treatment. Mean MI decreased significantly from 56.52 ± 23.35 to 32.75 ± 12.91 (p = 0.000). L value increased from 59.21 ± 2.22 before treatment to 61.60 ± 2.40 (p = 0.000) after therapy. The mean score of PGA was 3.76 ± 0.71, indicating a "moderate" clearance of the lesion. In patients' self-evaluations, 70 % of the patients rated the result as "good" to

  10. Cryogenic cooling for high power laser amplifiers

    Directory of Open Access Journals (Sweden)

    Perin J.P.

    2013-11-01

    Full Text Available Using DPSSL (Diode Pumped Solid State Lasers as pumping technology, PW-class lasers with enhanced repetition rates are developed. Each of the Yb YAG amplifiers will be diode-pumped at a wavelength of 940 nm. This is a prerequisite for achieving high repetition rates (light amplification duration 1 millisecond and repetition rate 10 Hz. The efficiency of DPSSL is inversely proportional to the temperature, for this reason the slab amplifier have to be cooled at a temperature in the range of 100 K–170 K with a heat flux of 1 MW*m−2. This paper describes the thermo-mechanical analysis for the design of the amplification laser head, presents a preliminary proposal for the required cryogenic cooling system and finally outlines the gain of cryogenic operation for the efficiency of high pulsed laser.

  11. A split-face, investigator-blinded comparative study on the efficacy and safety of Q-switched Nd:YAG laser plus microneedling with vitamin C versus Q-switched Nd:YAG laser for the treatment of recalcitrant melasma.

    Science.gov (United States)

    Ustuner, Pelin; Balevi, Ali; Ozdemir, Mustafa

    2017-11-01

    High recurrence has previously been reported in the treatment of melasma with low-fluence 1,064-nm Q-switched neodymium-doped yttrium aluminium garnet (QS-Nd:YAG) laser. On the other hand, the efficacy and safety of the QS-Nd:YAG laser plus microneedling with vitamin C have not been evaluated in patients with mixed-type melasma. Sixteen patients with recalcitrant dermal- or mixed-type melasma were included in the study. One side of patients' face was treated with QS-Nd:YAG laser plus microneedling with vitamin C (Group A) and the other side with QS-Nd:YAG laser alone (Group B) for four sessions at four-week intervals. Melasma Area Severity Index (MASI) scores and clinician's evaluation of clinical response were assessed monthly. Group A had a significantly lower mean MASI score and better treatment response than Group B according to clinician's evaluation. According to MASI scores, in Group B, two patients had a good response while 12 were unresponsive to treatment. Good or very good improvement was reported by 10 patients in Group A and three patients in Group B. Adverse effects and recurrence rates were similar in Groups A and B (31.3 and 43.8%, respectively). QS-Nd:YAG increases the blood circulation in the dermis, thereby enhancing the mechanical effect of microneedling to promote the penetration of vitamin C. Vitamin C application with microneedling immediately after treatment with QS-Nd:YAG laser is a promising adjunctive method for the treatment of recalcitrant melasma.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vainshenker, A E; Vilenskiy, A V; Kazakov, A A; Lysoy, B G; Mikhailov, L K; Pashkov, V A [Open Joint-Stock Company ' M.F. Stel' makh Polyus Research and Development Institute' , Moscow (Russian Federation)

    2013-02-28

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

  13. Generation of 220 mJ nanosecond pulses at a 10 Hz repetition rate with excellent beam quality in a diode-pumped Yb:YAG MOPA system.

    Science.gov (United States)

    Wandt, Christoph; Klingebiel, Sandro; Siebold, Mathias; Major, Zsuzsanna; Hein, Joachim; Krausz, Ferenc; Karsch, Stefan

    2008-05-15

    A novel all-diode-pumped master oscillator power amplifier system based on Yb:YAG crystal rods has been developed. It consists of a Q-switched oscillator delivering 3 mJ, 6.4 ns pulses at a 10 Hz repetition rate and an additional four-pass amplifier, which boosts the output energy to 220 mJ, while a close to TEM(00) beam quality could be observed. Additionally a simulation of the amplification was written that allows for further scaling considerations.

  14. Exploiting nonlinear properties of pure and Sn-doped Bi2Te2Se for passive Q-switching of all-polarization maintaining ytterbium- and erbium-doped fiber lasers.

    Science.gov (United States)

    Bogusławski, Jakub; Kowalczyk, Maciej; Iwanowski, Przemysław; Hruban, Andrzej; Diduszko, Ryszard; Piotrowski, Kazimierz; Dybko, Krzysztof; Wojciechowski, Tomasz; Aleszkiewicz, Marta; Sotor, Jarosław

    2017-08-07

    Due to their broadband nonlinear optical properties, low-dimensional materials are widely used for pulse generation in fiber and solid-state lasers. Here we demonstrate novel materials, Bi2Te2Se (BTS) and Sn-doped Bi2Te2Se (BSTS), which can be used as a universal saturable absorbers for distinct spectral regimes. The material was mechanically exfoliated from a bulk single-crystal and deposited onto a side-polished fiber. We have performed characterization of the fabricated devices and employed them in polarization-maintaining ytterbium- and erbium-doped fiber lasers. This enabled us to obtain self-starting passively Q-switched regime at 1 µm and 1.56 µm. The oscillators emitted stable, linearly polarized radiation with the highest single pulse energy approaching 692 nJ. Both lasers are characterized by the best performance observed in all-polarization maintaining Q-switched fiber lasers with recently investigated new saturable absorbers, which was enabled by a very high damage threshold of the devices. This demonstrates the great potential of the investigated materials for the ultrafast photonics community.

  15. High power visible light emitting diodes as pulsed excitation sources for biomedical photoacoustics.

    Science.gov (United States)

    Allen, Thomas J; Beard, Paul C

    2016-04-01

    The use of visible light emitting diodes (LEDs) as an alternative to Q-switched lasers conventionally used as photoacoustic excitation sources has been explored. In common with laser diodes, LEDs offer the advantages of compact size, low cost and high efficiency. However, laser diodes suitable for pulsed photoacoustic generation are typically available only at wavelengths greater than 750nm. By contrast, LEDs are readily available at visible wavelengths below 650nm where haemoglobin absorption is significantly higher, offering the prospect of increased SNR for superficial vascular imaging applications. To demonstrate feasibility, a range of low cost commercially available LEDs operating in the 420-620nm spectral range were used to generate photoacoustic signals in physiologically realistic vascular phantoms. Overdriving with 200ns pulses and operating at a low duty cycle enabled pulse energies up to 10µJ to be obtained with a 620nm LED. By operating at a high pulse repetition frequency (PRF) in order to rapidly signal average over many acquisitions, this pulse energy was sufficient to generate detectable signals in a blood filled tube immersed in an Intralipid suspension (µs' = 1mm(-1)) at a depth of 15mm using widefield illumination. In addition, a compact four-wavelength LED (460nm, 530nm, 590nm, 620nm) in conjunction with a coded excitation scheme was used to illustrate rapid multiwavelength signal acquisition for spectroscopic applications. This study demonstrates that LEDs could find application as inexpensive and compact multiwavelength photoacoustic excitation sources for imaging superficial vascular anatomy. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

  16. Protection Related to High-power Targets

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Target protection is an important part of machine protection. The beam power in high-intensity accelerators is high enough that a single wayward pulse can cause serious damage. Today's high-power targets operate at the limit of available technology, and are designed for a very narrow range of beam parameters. If the beam pulse is too far off centre, or if the beam size is not correct, or if the beam density is too high, the target can be seriously damaged. We will start with a brief introduction to high-power targets and then move to a discussion of what can go wrong, and what are the risks. Next we will discuss how to control the beam-related risk, followed by examples from a few different accelerator facilities. We will finish with a detailed example of the Oak Ridge Spallation Neutron Source target tune up and target protection.

  17. High power collimated diode laser stack

    Institute of Scientific and Technical Information of China (English)

    LIU Yuan-yuan; FANG Gao-zhan; MA Xiao-yu; LIU Su-ping; FENG Xiao-ming

    2006-01-01

    A high power collimated diode laser stack is carried out based on fast-axis collimation and stack packaging techniques.The module includes ten typical continuous wave (cw) bars and the total output power can be up to 368W at 48.6A.Using a cylindrical lens as the collimation elements,we can make the fast-axis divergence and the slow-axis divergence are 0.926 40 and 8.2060 respectively.The light emitting area is limited in a square area of 18.3 mm×11 mm.The module has the advantage of high power density and offers a wide potential applications in pumping and material processing.

  18. High Power Disk Loaded Guide Load

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; /SLAC

    2006-02-22

    A method to design a matching section from a smooth guide to a disk-loaded guide, using a variation of broadband matching, [1, 2] is described. Using this method, we show how to design high power loads. The load consists of a disk-loaded coaxial guide operating in the TE{sub 01}-mode. We use this mode because it has no electric field terminating on a conductor, has no axial currents, and has no current at the cylinder-disk interface. A high power load design that has -35 dB reflection and a 200 MHz, -20 dB bandwidth, is presented. It is expected that it will carry the 600 MW output peak power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell.

  19. High-Power Wind Turbine: Performance Calculation

    Directory of Open Access Journals (Sweden)

    Goldaev Sergey V.

    2015-01-01

    Full Text Available The paper is devoted to high-power wind turbine performance calculation using Pearson’s chi-squared test the statistical hypothesis on distribution of general totality of air velocities by Weibull-Gnedenko. The distribution parameters are found by numerical solution of transcendental equation with the definition of the gamma function interpolation formula. Values of the operating characteristic of the incomplete gamma function are defined by numerical integration using Weddle’s rule. The comparison of the calculated results using the proposed methodology with those obtained by other authors found significant differences in the values of the sample variance and empirical Pearson. The analysis of the initial and maximum wind speed influence on performance of the high-power wind turbine is done

  20. High Power Picosecond Laser Pulse Recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.