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Sample records for actively q-switched laser

  1. Actively Q-switched Raman fiber laser

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. G.; Podivilov, E. V.; Babin, S. A.

    2015-03-01

    A new scheme providing actively Q-switched operation of a Raman fiber laser (RFL) has been proposed and tested. The RFL consists of a 1 km single-mode fiber with a switchable loop mirror at one end and an angled cleaved output end. An 1080 nm pulse with microsecond duration is generated at the output by means of acousto-optic switching of the mirror at ~30 kHz in the presence of 6 W backward pumping at 1030 nm. In the proposed scheme, the generated pulse energy is defined by the pump energy distributed along the passive fiber, which amounts to 30 μJ in our case. The available pump energy may be increased by means of fiber lengthening. Pulse shortening is also expected.

  2. Modeling and optimization of actively Q-switched Nd-doped quasi-three-level laser

    NASA Astrophysics Data System (ADS)

    Yan, Renpeng; Yu, Xin; Li, Xudong; Chen, Deying; Gao, Jing

    2013-09-01

    The energy transfer upconversion and the ground state absorption are considered in solving the rate equations for an active Q-switched quasi-three-level laser. The dependence of output pulse characters on the laser parameters is investigated by solving the rate equations. The influence of the energy transfer upconversion on the pulsed laser performance is illustrated and discussed. By this model, the optimal parameters could be achieved for arbitrary quasi-three-level Q-switched lasers. An acousto-optical Q-switched Nd:YAG 946 nm laser is constructed and the reliability of the theoretical model is demonstrated.

  3. Short-pulse actively Q-switched Er:YAG lasers.

    PubMed

    Ottaway, David J; Harris, Lachlan; Veitch, Peter J

    2016-07-11

    We report the shortest duration pulses obtained to date from an actively Q-switched Er:YAG laser pumped by a low spectral and spatial brightness laser diode. The 14.5 ns, 6 mJ pulses were obtained using a 1470 nm laser diode end-pumped co-planar folded zigzag slab architecture. We also present an analytical model that accurately predicts the pulse energy-duration product achievable from virtually all Q-switched Er:YAG lasers and high repetition rate quasi-three-level Q-switched lasers in general. PMID:27410810

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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. PMID:19756079

  6. Active Q switching of a fiber laser with a microsphere resonator.

    PubMed

    Kieu, Khanh; Mansuripur, Masud

    2006-12-15

    We propose and demonstrate an active Q-switched fiber laser using a high-Q microsphere resonator as the Q-switching element. The laser cavity consists of an Er-doped fiber as the gain medium, a glass microsphere reflector (coupled through a fiber taper) at one end of the cavity, and a fiber Bragg grating reflector at the other end. The reflectivity of the microsphere is modulated by changing the gap between the microsphere and the fiber taper. Active Q switching is realized by oscillating the microsphere in and out of contact with the taper. Using this novel technique, we have obtained giant pulses (maximum peak power approximately 102 W, duration approximately 160 ns) at a low pump-power threshold (approximately 3 mW). PMID:17130905

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  8. A robust all-fiber active Q-switched 1-µm Yb3+ fiber laser

    NASA Astrophysics Data System (ADS)

    Sintov, Yoav; Goldring, Sharone; Pearl, Shaul; Lebiush, Eyal; Sfez, Bruno; Malka, Dror; Zalevsky, Zeev

    2015-09-01

    An all-fiber active Q-switched Yb3+-doped fiber laser at 1 µm is presented. The laser is composed of a ring resonator with an embedded all-fiber Q-switch element, based on a null coupler with an attached piezoelectric transducer (PZT). The PZT is used as an acoustic actuator, for inducing longitudinal acoustic disturbance along the null coupler and causing light coupling between the null coupler's ports. A stable operation is achieved with an overall average output power of up to 275 mW at various pulse repetition rates (PRR), ranging from 10 to 35 kHz and typical pulse energy of 15 μJ. In addition, a self-monitoring method is implemented by an embedded microcontroller, in order to maintain stable Q-switch performance, in changing environmental conditions. An average power of 8.5 W and pulse energy of 420 μJ at a PRR of 20 kHz are demonstrated in a master oscillator power amplifier containing the Q-switched laser, followed by a power amplifier.

  9. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  10. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    NASA Astrophysics Data System (ADS)

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-07-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  11. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    PubMed Central

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  12. Theoretical and experimental investigation of actively Q-switched Nd:YAG 946 nm laser with considering ETU effects

    NASA Astrophysics Data System (ADS)

    Yan, R.; Yu, X.; Li, X.; Chen, D.; Yu, J.

    2012-09-01

    A theoretical model on actively Q-switched Nd3+-doped quasi-three-level laser including the energy transfer upconversion and the ground state reabsorption is developed. The analytical expressions of the fractional thermal loading and the average output power are obtained, and the influence of ETU effects on laser performance for different repetition rate is analyzed. The average output power and the thermal focal length of the Q-switched 946 nm laser are acquired in experiment. The good agreement between the experimental data and theoretical results demonstrates the reliability of the theoretical model.

  13. Transform-limited pulses generated by an actively Q-switched distributed fiber laser.

    PubMed

    Cuadrado-Laborde, C; Pérez-Millán, P; Andrés, M V; Díez, A; Cruz, J L; Barmenkov, Yu O

    2008-11-15

    A single-mode, transform-limited, actively Q-switched distributed-feedback fiber laser is presented, based on a new in-line acoustic pulse generator. Our technique permits a continuous adjustment of the repetition rate that modulates the Q factor of the cavity. Optical pulses of 800 mW peak power, 32 ns temporal width, and up to 20 kHz repetition rates were obtained. The measured linewidth demonstrates that these pulses are transform limited: 6 MHz for a train of pulses of 10 kHz repetition rate, 80 ns temporal width, and 60 mW peak power. Efficient excitation of spontaneous Brillouin scattering is demonstrated. PMID:19015677

  14. Diode pumped Nd:YAG laser with active Q-switching and mode locking for hole drilling

    NASA Astrophysics Data System (ADS)

    Solokhin, S. A.; Sirotkin, A. A.; Garnov, S. V.

    2011-06-01

    A diode-pumped Nd:YAG laser operating with active-passive Q-switch mode locking, has been developed. The acousto-optic repetition train was one kilohertz with generated pulse train widths 65 ns, single pulse widths 200 ps and an average power of 6.5 W. Improvement of efficiency of small diameter deep holes laser drilling in different materials was studied.

  15. Intracavity optical parametric oscillator pumped by an actively Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Liu, Z. J.; Wang, Q. P.; Zhang, X. Y.; Liu, Z. J.; Wang, H.; Chang, J.; Fan, S. Z.; Ma, F. S.; Jin, G. F.

    2008-03-01

    A non-critically phase-matched KTiOPO4 optical parametric oscillator (OPO) intracavity pumped by a laser diode end-pumped acousto-optically Q-switchedNd:YAG laser is experimentally demonstrated. The highest average power is obtained at the pulse repetition rate (PRR) of around 15 kHz, which is different from the widely reported Nd:YVO4 laser pumped OPO in which the highest average power is obtained at a very high PRR, e.g. 80 kHz. With an incident laser diode power of 6.93 W and a pulse repetition rate of 15 kHz, an average signal power of 0.72 W is obtained with a peak power of 7.7 kW and an optical-to-optical conversion efficiency of 10.4%.

  16. Investigation of mechanically Q-switched lasers

    NASA Astrophysics Data System (ADS)

    Cole, Brian; Goldberg, Lew; Hough, Nathaniel; Nettleton, John

    2015-02-01

    Using a resonant scanner mirror Q-switch to provide a time varying change in cavity alignment, 1535nm lasers based on Er/Yb-doped glass and 1064nm lasers based on Nd:YAG were evaluated. Using a side pumping architecture, the Er/Yb glass laser used a compact mechanical Q-switch with a mirror rotation rate of 330 Rad/s, enabling generation of <3 mJ pulses with a pulse width of 16ns. The laser output was a diffraction limited TEM00 mode. A mechanical Q-switch based on a MEMS tilting mirror was also used; its performance in a laser cavity was found to be similar to the resonant mirror. The technique of mechanical Q-switching was also extended to a side pumped Nd:YAG laser (mirror sweep rate of 1300 Rad/s), enabling generation of Q-switched pulses of <30mJ and 25ns duration. The far-field divergence showed this laser to be highly multi-moded within the pump plane, with a measured beam-product-parameter greater than 30 mm-mRad.

  17. Q-Switching in a Neodymium Laser

    ERIC Educational Resources Information Center

    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. Graphene Q-switched, tunable fiber laser

    NASA Astrophysics Data System (ADS)

    Popa, D.; Sun, Z.; Hasan, T.; Torrisi, F.; Wang, F.; Ferrari, A. C.

    2011-02-01

    We demonstrate a wideband-tunable Q-switched fiber laser exploiting a graphene saturable absorber. We get ˜2 μs pulses, tunable between 1522 and 1555 nm with up to ˜40 nJ energy. This is a simple and low-cost light source for metrology, environmental sensing, and biomedical diagnostics.

  19. A random Q-switched fiber laser.

    PubMed

    Tang, Yulong; Xu, Jianqiu

    2015-01-01

    Extensive studies have been performed on random lasers in which multiple-scattering feedback is used to generate coherent emission. Q-switching and mode-locking are well-known routes for achieving high peak power output in conventional lasers. However, in random lasers, the ubiquitous random cavities that are formed by multiple scattering inhibit energy storage, making Q-switching impossible. In this paper, widespread Rayleigh scattering arising from the intrinsic micro-scale refractive-index irregularities of fiber cores is used to form random cavities along the fiber. The Q-factor of the cavity is rapidly increased by stimulated Brillouin scattering just after the spontaneous emission is enhanced by random cavity resonances, resulting in random Q-switched pulses with high brightness and high peak power. This report is the first observation of high-brightness random Q-switched laser emission and is expected to stimulate new areas of scientific research and applications, including encryption, remote three-dimensional random imaging and the simulation of stellar lasing. PMID:25797520

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

    NASA Astrophysics Data System (ADS)

    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.

  1. High-efficient diode-pumped actively Q-switched Nd:YAG/KTP Raman laser at 1096 nm wavelength

    NASA Astrophysics Data System (ADS)

    Su, Fufang; Zhang, Xingyu; Wang, Weitao; Cong, Zhenhua; Shi, Men; Yang, Xiuqin; Kong, Weijin; Ma, Lili; Wu, Wendi

    2013-09-01

    With Nd:YAG as the gain medium and KTP crystal as the Raman medium, the characteristics of an LD pumped intracavity actively Q-switched Nd:YAG/KTP Raman laser at 1096 nm wavelength were studied. The output characteristics of 1096 nm were investigated. At a pulse repetition rate of 30 kHz an average power up to 1.97 W was obtained with the incident pump power of 11.75 W, corresponding to a diode-to-Stokes conversion efficiency of 16.8%.

  2. Q-switched laser prelase detection circuit

    NASA Technical Reports Server (NTRS)

    Lockard, George E.

    1991-01-01

    A compact electronic circuit was developed to detect prelasing in Q-swithed pulsed laser systems and once detected to shut down the laser before the next laser pulse occurs. The circuit is small, compact, and uses a minimum of components which makes it quite economical, thus readily lending itself to commercial applications. It can easily be incorporated into virtually any Q-switched laser system or reliability of a laser system by reducing a source of possible costly optical damage. The circuit operation and instrument requirements necessary to incorporate the circuit into a laser system are discussed.

  3. Rate equations for ruby and alexandrite Q-switched lasers

    NASA Astrophysics Data System (ADS)

    Sulc, Jan; Jelinkova, Helena

    2003-07-01

    To have a complex view on giant pulse generation, a more precise computer model of the build up Q-switch pulse in solid-state laser was realized. As a time starting point of the rate equation calculation, the moment of a flashlamp trigger was chosen. A system of three or four main differential rate equations describes the energy transfer from a pumping source - capacitor to an output giant pulse. Two laser active media, i.e. ruby and alexandrite, were examined with this model. A passive Q-switch ruby laser needs solving of the system of four differential equations; three differential equations gave the computer results for electro-optically Q-switched alexandrite laser.

  4. Circuit Stops Prelasing In A Q-Switched Laser

    NASA Technical Reports Server (NTRS)

    Lockard, George E.

    1995-01-01

    Protective shutdown circuit stops prelasing in Q-switched laser operating at pulse-repetition rate of about 10 Hz. During normal operation, Q-switch prevents emission of light from laser cavity during application of Q-switch-trigger pulse. When circuit detects prelasing, it triggers relay turning off laser power supply. Circuit integrated into almost any Q-switched-laser system, provided one gains access to laser light, Q-switch-trigger pulse, and safety-interlock line of laser power supply.

  5. Spatial filter for Q-switched lasers

    NASA Technical Reports Server (NTRS)

    Wuerker, R. F.; Heflinger, L. O. (Inventor)

    1977-01-01

    A spatial filtered Q-switched laser system is reported that prevents ionization of air in close proximity to the aperture of the spatial filter. A compound lens system having an astigmatic focus is positioned between the laser and the spatial filter for defocusing the light beam emanating from the laser in the vicinity of the aperture of the spatial filter to an intensity below that which produces ionization of air. The preferred construction of the compound lens system as viewed from the laser comprises a cylindrical lens and a pair of positive lenses.

  6. All fiber passively Q-switched laser

    DOEpatents

    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.

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

    PubMed

    Li, Shuo; Liu, Lei; Chen, Rongzhang; Nelsen, Bryan; Huang, Xi; Lu, Yongfeng; Chen, Kevin

    2016-03-01

    This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications. PMID:27036765

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

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Liu, Lei; Chen, Rongzhang; Nelsen, Bryan; Huang, Xi; Lu, Yongfeng; Chen, Kevin

    2016-03-01

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

  9. Low threshold, actively Q-switched Nd 3+:YVO 4 self-Raman laser and frequency doubled 588 nm yellow laser

    NASA Astrophysics Data System (ADS)

    Wang, Baoshan; Tan, Huiming; Peng, Jiying; Miao, Jieguang; Gao, Lanlan

    2007-03-01

    We reported an actively Q-switched, intracavity Nd3+:YVO4 self-Raman laser at 1176 nm with low threshold and high efficiency. From the extracavity frequency doubling by use of LBO nonlinear crystal, over 3.5 mW, 588 nm yellow laser is achieved. The maximum Raman laser output at is 182 mW with 1.8 W incident pump power. The threshold is only 370 mW at a pulse repetition frequency of 5 kHz. The optical conversion efficiency from incident to the Raman laser is 10%, and 1.9% from Raman laser to the yellow.

  10. Injection Seeding Of A Q-Switched Alexandrite Laser

    NASA Technical Reports Server (NTRS)

    Zukowski, Barbara J. K.; Glesne, Thomas R.; Schwemmer, Geary; Czechanski, James P.; Kay, Richard B.

    1992-01-01

    Experiment demonstrates that standing-wave, Q-switched, tunable alexandrite laser can be injection-seeded to increase stability of output frequency and significantly reduce bandwidth from 750 GHz to 180 MHz. Injecting laser acts as oscillator or master, while Q-switched laser into which ouput of seed laser injected acts as amplifier or slave.

  11. Actively Q-switched 2.9 μm Ho(3+)Pr(3+)-doped fluoride fiber laser.

    PubMed

    Hu, Tomonori; Hudson, Darren D; Jackson, Stuart D

    2012-06-01

    We report an efficient Q-switched Ho(3+)Pr(3+)-doped fluoride fiber laser, producing a peak power of 77 W, with pulse width of 78 ns. A slope efficiency of 20% with respect to the launched pump power was achieved. A TeO(2) acousto-optic modulator allowed continuous tunability of the pulse repetition frequency from 40 to 300 kHz. PMID:22660149

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

    SciTech Connect

    Barmenkov, Yuri O. Kir'yanov, Alexander V.; Cruz, Jose L.; Andres, Miguel V.

    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.

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

    PubMed

    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. PMID:22418199

  14. Q-switched fiber laser based on an acousto-optic modulator with injection seeding technique.

    PubMed

    Li, Wencai; Liu, Haowei; Zhang, Ji; Long, Hu; Feng, Sujuan; Mao, Qinghe

    2016-06-10

    The operation mechanism and the pulse property of an actively Q-switched erbium-doped fiber laser based on an acousto-optic modulator (AOM) switch with the injection seeding technique are investigated. Our results show that the Q-switched pulses can be locked to oscillate near a fixed frequency higher than that of the seed laser, though the frequency-shift effect of the AOM impedes stable cavity mode oscillations. The operation mechanism of such Q-switch fiber lasers can be explained by the mutual locking-in among the shifted frequency components originated from the injected coherence seed with the help of the gain dynamics of the Q-switch cavity. Moreover, narrow-linewidth Q-switched pulses with different repetition rates can be obtained with different cavity lengths for incredibly stable output pulses without any use of cavity-stabilized techniques. PMID:27409015

  15. Detection and analysis on versatile coding strategies of high frequency active Q-switched Nd:YVO4 laser for irradiance of different targets

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ashraf F.; Talaat, Mahmoud

    2014-12-01

    We report an active Q-switching with different coded schemes generated in the high power diode end pumped Nd:YVO4 laser (DEPSS) using two different techniques of special combination of optical choppers and acousto-optic modulator (AOM) at higher repetition rates of 100 kHz for the first time to the best of our knowledge in any practical laser target designation (LTD) systems. The highest peak power of 95.4 kW with the lowest pulse repetition frequency of 222 Hz and pulse width of 46 ns at FWHM with the pulse-to-pulse stability of ~95% was measured at certain regime of operation. Special modulation and coding of high stable, high peak power Nd:YVO4 laser pulses at 1064 nm using the combination of different optical chopper blades were achieved. A high peak power of more than 4.84 kW with the shortest pulse width of 25 ns at FWHM has been obtained using an acousto-optic modulator (AOM) as an active Q-switched. The pulse-to-pulse stability was measured and improved to be ~97% at high repetition rate ranges from 10 kHz to 100 kHz. The correlation between the coded laser irradiation (transmitted) and the scattered (received) laser signals for three different targets materials of sand, wood and metal using this laser designation system are examined and discussed.

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

    PubMed

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

    2013-12-01

    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. PMID:24514499

  17. High-efficiency diode-pumped actively Q-switched ceramic Nd:YAG/BaWO₄ Raman laser operating at 1666 nm.

    PubMed

    Zhang, H N; Chen, X H; Wang, Q P; Zhang, X Y; Chang, J; Gao, L; Shen, H B; Cong, Z H; Liu, Z J; Tao, X T; Li, P

    2014-05-01

    A diode-pumped actively Q-switched Raman laser employing BaWO4 as the Raman active medium and a ceramic Nd:YAG laser operating at 1444 nm as the pump source is demonstrated. The first-Stokes-Raman generation at 1666 nm is achieved. With a pump power of 20.3 W and pulse repetition frequency rate of 5 kHz, a maximum output power of 1.21 W is obtained, which is the highest output power for a 1.6 μm Raman laser. The corresponding optical-to-optical conversion efficiency is 6%; the pulse energy and peak power are 242 μJ and 8.96 kW, respectively. PMID:24784068

  18. Simple technique for sequential Q-switching of molecular lasers.

    NASA Technical Reports Server (NTRS)

    Lucht, R. A.; Allario, F.; Jarrett, O., Jr.

    1972-01-01

    A simple technique for sequentially Q-switching molecular lasers is discussed in which an optical scanner is used as an optical folding element in a laser cavity consisting of a stationary diffraction grating and partially reflecting mirror. Sequential Q-switching of a conventional CO2 laser is demonstrated in which over sixty-two transitions between 9.2 and 10.8 microns are observed. Rapid repetition rates (200 Hz) and narrow laser pulses (less than 5 microsec) allow conventional signal processing techniques to be used with this multiwavelength laser source which is a versatile tool for laser propagation studies, absorption spectroscopy, and gain measurements. Results of a preliminary experiment demonstrating the utility of measuring selective absorption of CO2 laser wavelengths by C2H4 are shown.

  19. High power VCSEL array pumped Q-switched Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Xiong, Yihan; Van Leeuwen, Robert; Watkins, Laurence S.; Seurin, Jean-Francois; Xu, Guoyang; Miglo, Alexander; Wang, Qing; Ghosh, Chuni

    2012-03-01

    Solid-state lasers pumped by high-power two-dimensional arrays of vertical-cavity surface-emitting lasers (VCSELs) were investigated. Both end-pumping and side-pumping schemes of Nd:YAG lasers with high power kW-class 808 nm VCSEL pump modules were implemented. For one application 10 mJ blue laser pulses were obtained from a frequencydoubled actively Q-switched VCSEL-array dual side-pumped Nd:YAG laser operating at 946 nm. For another application 10 mJ green laser pulses were obtained from a frequency-doubled passively Q-switched VCSEL-array endpumped Nd:YAG laser operating at 1064 nm. Both QCW and CW pumping schemes were investigated to achieve high average Q-switched power.

  20. 100-megawatt power Q-switched Er-glass laser

    NASA Astrophysics Data System (ADS)

    Taboada, John; Taboada, John M.; Stolarski, David J.; Zohner, Justin J.; Chavey, Lucas J.; Hodnett, Harvey M.; Noojin, Gary D.; Thomas, Robert J.; Kumru, Semih S.; Cain, Clarence P.

    2006-02-01

    A very high energy Q-switched Er-glass laser is reported. We incorporated a rotating, resonant mirror/Porro-cavity reflector optical arrangement to achieve very high shutter speeds on the cavity Q of a laser designed for energetic, flashlamp-pumped, 600-μs, 1540-nm pulses. Reproducible 3.75-J, 35-ns, 1533-nm laser pulses were obtained at a repetition rate less than 1 minute. Our work shows that reliable, very high energy, Q-switched, Er-glass laser pulses at 1533 nm can be generated mechanically with no apparent damage to laser cavity components. We demonstrate the applications of this "eye safe" wavelength to energetic processes such as LIBS and materials processing. The laser could also serve as a new tool for bioeffects studies and targeting applications.

  1. Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

    SciTech Connect

    Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

    1997-12-01

    This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

  2. Q-Switched Alexandrite Laser-induced Chrysiasis

    PubMed Central

    Victor Ross, E.

    2015-01-01

    Background: Chyriasis is an uncommon side effect that occurs in patients who are receiving prolonged treatment with either intravenous or intramuscular gold as a distinctive blue-gray pigmentation of light-exposed skin. Laser-induced chrysiasis is a rarely described phenomenon in individuals who have received systemic gold and are subsequently treated with a Q-switched laser. Purpose: To describe the characteristics of patients with laser-induced chrysiasis. Methods: The authors describe a 60-year-old woman who developed chrysiasis at Q-switched alexandrite laser treatment sites. They also reviewed the medical literature using PubMed, searching the terms chrysiasis, gold, and laser-induced. Patient reports and previous reviews of these subjects were critically assessed and the salient features are presented. Results: Including the authors’ patient, laser-induced chrysiasis has been described in five Caucasian arthritis patients (4 women and 1 man); most of the patients had received more than 8g of systemic gold therapy during a period of 3 to 13 years. Gold therapy was still occurring or had been discontinued as long as 26 years prior to laser treatment. All of the patients immediately developed blue macules at the Q-switched laser treatment site. Resolution of the dyschromia occurred in a 70-year-old woman after two treatment sessions with a long-pulsed ruby laser and the authors’ patient after a sequential series of laser sessions using a long-pulsed alexandrite laser, followed by a nonablative fractional laser and an ablative carbon dioxide laser. Conclusion: Laser-induced chrysiasis has been observed following treatment with Q-switched lasers in patients who are receiving or have previously been treated with systemic gold. It can occur decades after treatment with gold has been discontinued. Therefore, inquiry regarding a prior history of treatment with gold—particularly in older patients with arthritis—should be considered prior to treatment with a Q-switched

  3. Q-Switched Nd: YAG Laser Micro-Machining System

    SciTech Connect

    Messaoud, S.; Allam, A.; Siserir, F.; Bouceta, Y.; Kerdja, T.; Ouadjaout, D.

    2008-09-23

    In this paper, we present the design of a low cost Q-switched Nd: YAG laser micro-machining system for photo masks fabrication. It consists of: Nd:YAG laser source, beam delivery system, X-Y table, PC, The CCD camera and TV monitor. The synchronization between the laser source and the X-Y table is realised by NI PCI-7342, the two axis MID-7602 and LabVIEW based program. The first step of this work consists of engraving continuous and discontinuous lines on a thin film metal with a 100 {mu}m resolution by using the YG 980 Quantel Q-switched Nd:YAG laser.

  4. Q-switched Raman laser system

    DOEpatents

    George, E.V.

    Method and apparatus for use of a Raman or Brillouin switch together with a conventional laser and a saturable absorber that is rapidly bleached at a predeterimined frequency nu = nu/sub O/, to ultimately produce a Raman or Brillouin pulse at frequency nu = nu/sub O/ +- nu /sub Stokes/.

  5. Q-Switched Raman laser system

    DOEpatents

    George, E. Victor

    1985-01-01

    Method and apparatus for use of a Raman or Brillouin switch together with a conventional laser and a saturable absorber that is rapidly bleached at a predetermined frequency .nu.=.nu..sub.0, to ultimately produce a Raman or Brillouin pulse at frequency .nu.=.nu..sub.0 .+-..nu..sub.Stokes.

  6. Efficient Q-switched Tm:YAG ceramic slab laser.

    PubMed

    Zhang, Shuaiyi; Wang, Mingjian; Xu, Lin; Wang, Yan; Tang, Yulong; Cheng, Xiaojin; Chen, Weibiao; Xu, Jianqiu; Jiang, Benxue; Pan, Yubai

    2011-01-17

    Characteristics of Tm:YAG ceramic for high efficient 2-μm lasers are analyzed. Efficient diode end-pumped continuous-wave and Q-switched Tm:YAG ceramic lasers are demonstrated. At the absorbed pump power of 53.2W, the maximum continuous wave (cw) output power of 17.2 W around 2016 nm was obtained with the output transmission of 5%. The optical conversion efficiency is 32.3%, corresponding to a slope efficiency of 36.5%. For Q-switched operation, the shortest width of 69 ns was achieved with the pulse repetition frequency of 500 Hz and single pulse energy of 20.4 mJ, which indicates excellent energy storage capability of the Tm:YAG ceramic. PMID:21263612

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

    SciTech Connect

    Kim, Jun Wan; Young Choi, Sun; Jun Ahn, Kwang; Yeom, Dong-Il E-mail: rotermun@ajou.ac.kr; Rotermund, Fabian E-mail: rotermun@ajou.ac.kr; Aravazhi, Shanmugam; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Bae, Sukang

    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.

  8. Tm:germanate Fiber Laser: Tuning And Q-switching

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J.; DeYoung, R. J.; Jiang, Shibin

    2007-01-01

    A Tm:germanate fiber laser produced >0.25 mJ/pulse in a 45 ns pulse. It is capable of producing multiple Q-switched pulses from a single p ump pulse. With the addition of a diffraction grating, Tm:germanate f iber lasers produced a wide, but length dependent, tuning range. By s electing the fiber length, the tuning range extends from 1.88 to 2.04 ?m. These traits make Tm:germanate lasers suitable for remote sensin g of water vapor.

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

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Lesh, James R.

    1993-01-01

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

  10. Effects of axial nonuniformity in modeling Q-switched lasers

    SciTech Connect

    Stone, D.H. )

    1992-10-01

    Generic Q-switched laser pulses are calculated using a point model and a traveling wave model. Results indicate that the point model approach commonly used in rate equation modeling is inadequate for large initial inversions, large internal losses, or large fractional outcoupling. The point model typically overestimates peak power and energy and distorts the pulse shape. A simple traveling wave model is developed which easily describes these cases. The optimum outcoupling to maximize peak power varies significantly between the two models. 9 refs.

  11. Theory of the optimally coupled Q-switched laser

    NASA Technical Reports Server (NTRS)

    Degnan, John J.

    1989-01-01

    The general equations describing Q-switched laser operation are transcendental in nature and require numerical solutions, which greatly complicates the optimization of real devices. Here, it is shown that, using the mathematical technique of Lagrange multipliers, one can derive simple analytic expressions for all of the key parameters of the optimally coupled laser, i.e., one which uses an optimum reflector to obtain maximum laser efficiency for a given pump level. These parameters can all be expressed as functions of a single dimensionless variable z, defined as the ratio of the unsaturated small-signal gain to the dissipative (nonuseful) optical loss, multiplied by a few simple constants. Laser design tradeoff studies and performance projections can be accomplished quickly with the help of several graphs and a simple hand calculator. Sample calculations for a high-gain Nd:YAG and a low-gain alexandrite laser are presented as illustrations of the technique.

  12. Passively Q-switched side pumped monolithic ring laser

    NASA Technical Reports Server (NTRS)

    Li, Steven X. (Inventor)

    2012-01-01

    Disclosed herein are systems and methods for generating a side-pumped passively Q-switched non-planar ring oscillator. The method introduces a laser into a cavity of a crystal, the cavity having a round-trip path formed by a reflection at a dielectrically coated front surface, a first internal reflection at a first side surface of the crystal at a non-orthogonal angle with the front, a second internal reflection at a top surface of the crystal, and a third internal reflection at a second side surface of the crystal at a non-orthogonal angle with the front. The method side pumps the laser at the top or bottom surface with a side pump diode array beam and generates an output laser emanating at a location on the front surface. The design can include additional internal reflections to increase interaction with the side pump. Waste heat may be removed by mounting the crystal to a heatsink.

  13. Simulation of tunable Cr:YSO Q-switched Cr:LiSAF laser

    NASA Astrophysics Data System (ADS)

    Chen, Hsiu-Fen; Hsieh, Shang-Wei; Kuo, Yen-Kuang

    2005-01-01

    In this work, we numerically investigate the passive Q-switching performance of the tunable Cr:YSO Q-switched Cr:LiSAF laser over its entire tuning range. Specifically, the optical performance of the Cr:YSO Q-switched Cr:LiSAF laser as functions of the initial population in the ground state of the Cr:YSO saturable absorber, the pumping rate, the reflectivity of the output coupler, and the dissipative loss inside the laser cavity are studied. Simulation results show that the Cr:YSO is an effective saturable absorber Q switch for the Cr:LiSAF laser over its entire tuning range. Unlike the Cr:YSO Q-switched alexandrite laser and the Cr:YSO Q-switched Cr:LiCAF laser, the Cr:YSO Q-switched Cr:LiSAF laser has similar passive Q-switching performance when the laser polarization is along each of the three principal axes of the Cr:YSO. The results obtained numerically in this work are in good agreement with those obtained experimentally by other researchers. Our simulation results indicate that, a Q-switched laser pulse with an output energy of 10 mJ and a pulse width of 17 ns may be obtained at 850 nm, the peak of its tuning spectrum.

  14. Repetitively Q-switched Nd:BeL lasers

    NASA Technical Reports Server (NTRS)

    Degnan, J.; Birnbaum, M.; Deshazer, L. G.

    1979-01-01

    The thermal and mechanical characteristics which will ultimately limit the performance of Nd:BeL at high average power levels were investigated. The output beam characteristics (pulse width, peak power, beam dimensions and collimation) were determined at high repetition rates for both Nd:BeL and Nd:YAG. The output of Nd:BeL was shown to exceed that of Nd:YAG by a factor of 2.7 at low Q-switched repetition rates (1 Hz). This result follows from the smaller stimulated emission cross section of x-axis Nb:BeL compared to that of NdYAG by the same factor. At high repetition rates (10 Hz) the output of Nd:Bel falls to a level of three-fifths of its low repetition rate value while under similar tests the output of Nd:YAG remains essentially constant. A comparison of the measured values of the elasto-optic coefficients, the dn/dT values and the linear expansion coefficients for BeL and YAG failed to provide an explanation for the performance of BeL; however, thermal lensing was observed in Nd:BeL. Results imply that the output of a high repetition rate Q-switched Nd:BeL laser (high thermal loading) could be dramatically increased by utilization of a resonator design to compensate for the thermal lensing effects.

  15. Eye-safe actively Q-switched diode-pumped lasers with intracavity Raman conversion in YVO4, KGd(WO4)2, PbWO4, and Ba(NO3)2 crystals

    NASA Astrophysics Data System (ADS)

    Dashkevich, V. I.; Shpak, P. V.; Voitikov, S. V.; Chulkov, R. V.; Grabtchikov, A. S.; Cheshev, E. A.; El-Desouki, M.; Orlovich, V. A.

    2015-09-01

    We have investigated the self-Raman and intracavity Raman frequency conversion of the end-diode-pumped acoustooptic Q-switched Nd:YVO4 laser radiation to eye-safe radiation. The 1st Stokes oscillation in YVO4 (Nd:YVO4), KGd(WO4)2, PbWO4, and Ba(NO3)2 crystals excited by the laser radiation at a wavelength of 1342 nm permits obtaining oscillations at 1524, 1496 or 1527, 1527, and 1562 nm wavelengths, respectively. We have obtained pulsed lasing with a repetition rate of 2-20 kHz, an output energy of 37-95 μJ, and a duration of 6-8 ns. We propose a model of the actively Q-switched intracavity Raman laser taking into account the real switching off/on times of the actively Q-switch and the excited state absorption in the active medium. We used this model to simulate the dynamics of the self-Raman Nd:YVO4 laser. The proposed model gives results that agree fairly well with the experimental data.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  17. Theory of the optimally coupled Q-switched laser

    SciTech Connect

    Degnan, J.J.

    1989-02-01

    The general equations describing Q-switched laser operation are transcendental in nature and require numerical solutions. This greatly complicates the optimization of real devices. In this paper, we demonstrate that, using the mathematical technique of Lagrange multipliers, one can derive simple analytic expressions for all of the key parameters of the optimally coupled laser, i.e., one which uses an optimum reflector to obtain maximum laser efficiency for a given pump level. These parameters (which include the optimum reflectivity, output energy, extraction efficiency, pulsewidth, peak power, etc.) can all be expressed as functions of a single dimensionless variable z, defined as the ratio of the unsaturated small-signal gain to the dissipative (non-useful) optical loss, multiplied by a few simple constants. Laser design tradeoff studies and performance projections can be accomplished quickly with the help of several graphs and a simple hand calculator. Sample calculations for a high-gain Nd:YAG and a low-gain alexandrite laser are presented as illustrations of the technique.

  18. Q-switched ruby laser in cosmetic dermatology

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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.

  20. Method and apparatus for detection and control of prelasing in a Q-switched laser

    NASA Technical Reports Server (NTRS)

    Lockard, George E. (Inventor)

    1994-01-01

    The present invention detects prelasing in a Q-switch laser and terminates laser operation upon such detection. A detector senses the presence of light beyond a Q-switch and generates an appropriate electrical signal. A comparison stage circuit compares this detector signal with an established threshold value indicative of prelasing and generates a trigger signal if this detector signal exceeds this threshold value. A control stage circuit receives both this trigger value and a sampled Q-switch signal indicative of an opening of the Q-switch. The control stage circuit terminates operation of the laser if the trigger signal from the comparison stage is received while the sampled Q-switch signal is being received to avoid the effects of prelasing. Appropriate delays and timing sequences are established.

  1. Experimental study of electro-optical Q-switched pulsed Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    A, Maleki; M Kavosh, Tehrani; H, Saghafifar; M, H. Moghtader Dindarlu

    2016-03-01

    We report the specification of a compact and stable side diode-pumped Q-switched pulsed Nd:YAG laser. We experimentally study and compare the performance of the pulsed Nd:YAG laser in the free-running and Q-switched modes at different pulse repetition rates from 1 Hz to 100 Hz. The laser output energy is stabilized by using a special configuration of the optical resonator. In this laser, an unsymmetrical concave-concave resonator is used and this structure helps the mode volume to be nearly fixed when the pulse repetition rate is increased. According to the experimental results in the Q-switched operation, the laser output energy is nearly constant around 70 mJ with an FWHM pulse width of 7 ns at 100 Hz. The optical-to-optical conversion efficiency in the Q-switched regime is 17.5%.

  2. Optical performance of Ho:YLF Q-switched Tm:YAG laser system

    NASA Astrophysics Data System (ADS)

    Chang, Yi-An; Kuo, Yen-Kuang

    2002-09-01

    The absorption cross-section of the Ho:YLF crystal is close to the emission cross-section of the Tm:YAG laser. According to the passive Q-switching theory, a giant laser pulse cannot be generated from the Ho:YLF Q-switched Tm:YAG laser system unless an internal focusing lens is utilized. In a previous work we experimentally demonstrated that passive Q-switching of the 2017-nm, flashlamp pumped Tm,Cr:YAG laser with a Ho:YLF saturable absorber could be obtained with an internal focusing lens. In this paper, we theoretically investigate the optical performance of the Ho:YLF Q-switched Tm:YAG laser system by solving the coupled rate equations. The simulation results indicate that the results obtained numerically are in good agreement with that obtained experimentally. Moreover, we study the passive Q-switching performance of the Ho:YLF Q-switched Tm:YAG laser system as functions of the reflectivity of the output coupler, the initial population of the saturable absorber ground state, the laser pumping rate, and the loss inside the laser resonator. On the other hand, assuming that a polarizer is utilized inside the laser cavity, we explore the passive Q-switching performance of the Ho:YLF Q-switched Tm:YAG laser system when the polarization of the laser light is along different direction between the two saturable absorber principal axes. Effect of the relative position between the saturable absorber and the output coupler is also investigated.

  3. Oscillatory phenomena and Q switching in a model for laser with a saturable absorber

    SciTech Connect

    Antoranz, J.C.; Gea, J.; Velarde, M.G.

    1981-12-28

    Sufficiently long population decay times and sufficiently short dipole decay times in a single-mode laser with saturable absorber permit passive Q switching in the form of a hard-mode sustained relaxation oscillation.

  4. Treatment of large bulla formation after tattoo removal with a q-switched laser.

    PubMed

    Kirby, William; Kartono, Francisca; Desai, Alpesh; Kaur, Ravneet R; Desai, Tejas

    2010-01-01

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

  5. 1357 nm passively Q-switched crystalline ceramic laser based on multilayer graphene

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  6. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

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

    PubMed Central

    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

  8. Single-frequency, 500-ns laser pulses generated by a passively Q-switched Nd laser

    NASA Astrophysics Data System (ADS)

    Jones, D. C.; Rockwell, D. A.

    1993-03-01

    Accounts are given of the construction and performance of a narrowband Q-switched oscillator that addresses requirements for heavy amplifier saturation as well as a degree of temporal pulse-shaping prior to oscillator beam injection into the amplifier chain that can avoid the severe temporal distortion imposed by amplifier saturation. This oscillator encompasses a lamp-pumped Cr:Nd:GSGG laser rod, a saturable absorber Q switch, and several etalon surfaces forming the output coupler. This device can be used in large baseline holography.

  9. Q-switched and mode-locked Er{sup 3+}-doped fibre laser using a single-multi-single fibre filter and piezoelectric

    SciTech Connect

    Ji Wang; Yunjun Zhang; Aotuo Dong; Xiaoxin Xu; Youlun Ju; Baoquan Yao

    2014-04-28

    The active Q-switched and passive mode-locked Er{sup 3+}-doped all-fibre laser is presented. The fibre laser centre wavelength is located at 1563 nm and determined by the homemade singlemulti- single (SMS) in-line fibre filter. The laser spectrum width is nearly 0.1 nm. The active Q-switched mechanism relies on the polarisation state control using a piezoelectric to press a segment of passive fibre on the circular cavity. The nonlinear polarisation rotation technology is used to realise the passive self-started modelocked operation. In the passive mode-locked regimes, the output average power is 2.1 mW, repetition frequency is 11.96 MHz, and single pulse energy is 0.18 nJ. With the 100-Hz Q-switched regimes running, the output average power is 1.5 mW. The total Q-switched pulse width is 15 μs, and every Q-switched pulse is made up by several tens of mode-locked peak pulses. The calculated output pulse energy of the Q-switched fibre laser is about 15 μJ, and the energy of every mode-locked pulse is about 64–68 nJ during a Q-switched pulse taking into account the power fraction propagating between pulses. (lasers)

  10. Theoretical and experimental analysis of injection seeding a Q-switched alexandrite laser

    NASA Technical Reports Server (NTRS)

    Prasad, C. R.; Lee, H. S.; Glesne, T. R.; Monosmith, B.; Schwemmer, G. K.

    1991-01-01

    Injection seeding is a method for achieving linewidths of less than 500 MHz in the output of broadband, tunable, solid state lasers. Dye lasers, CW and pulsed diode lasers, and other solid state lasers have been used as injection seeders. By optimizing the fundamental laser parameters of pump energy, Q-switched pulse build-up time, injection seed power and mode matching, one can achieve significant improvements in the spectral purity of the Q-switched output. These parameters are incorporated into a simple model for analyzing spectral purity and pulse build-up processes in a Q-switched, injection-seeded laser. Experiments to optimize the relevant parameters of an alexandrite laser show good agreement.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Q-switched and mode-locked Er3+-doped fibre laser using a single-multi-single fibre filter and piezoelectric

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Zhang, Yunjun; Dong, Aotuo; Xu, Xiaoxin; Ju, Youlun; Yao, Baoquan

    2014-04-01

    The active Q-switched and passive mode-locked Er3+-doped all-fibre laser is presented. The fibre laser centre wavelength is located at 1563 nm and determined by the homemade singlemulti- single (SMS) in-line fibre filter. The laser spectrum width is nearly 0.1 nm. The active Q-switched mechanism relies on the polarisation state control using a piezoelectric to press a segment of passive fibre on the circular cavity. The nonlinear polarisation rotation technology is used to realise the passive self-started modelocked operation. In the passive mode-locked regimes, the output average power is 2.1 mW, repetition frequency is 11.96 MHz, and single pulse energy is 0.18 nJ. With the 100-Hz Q-switched regimes running, the output average power is 1.5 mW. The total Q-switched pulse width is 15 μs, and every Q-switched pulse is made up by several tens of mode-locked peak pulses. The calculated output pulse energy of the Q-switched fibre laser is about 15 μJ, and the energy of every mode-locked pulse is about 64-68 nJ during a Q-switched pulse taking into account the power fraction propagating between pulses.

  13. CONTROL OF LASER RADIATION PARAMETERS: Passive Q switching of a neodymium laser by a Cr4+ : YAG crystal switch

    NASA Astrophysics Data System (ADS)

    Il'ichev, Nikolai N.; Gulyamova, E. S.; Pashinin, Pavel P.

    1997-11-01

    Theoretical and experimental investigations were made of passive Q switching of a neodymium laser by a Cr4+ : YAG switch. Analytic expressions were derived for estimating the output energy of the TEM00 mode of a passively Q-switched laser from the known parameters of the Cr4+ : YAG switch, of the active element, and of the cavity. The adopted description makes it possible to cover the range from generation of the first spike of a free-running transient to generation of a giant pulse. An experimental study was made of the dependence of the output energy on the cavity parameters, on the material of the active element (in this investigation it was Nd :YAG and Cr, Nd : GSGG), and on the angle of rotation of the Cr4+ : YAG switch. The experimental results obtained agreed to within 30% with calculations.

  14. Optimization of a Fabry-Perot Q-switch fiber optic laser

    NASA Astrophysics Data System (ADS)

    Armas Rivera, Ivan; Beltrán Pérez, Georgina; Kuzin, Evgene; Castillo Mixcóatl, Juan; Muñoz Aguirre, Severino

    2013-11-01

    Optical fiber Q-Switch lasers have been used in a variety of application areas in science as well as in industry owing to their multiple characteristics. A possible application is that owing to their high output power they can be used as pumping sources for supercontinuum generation. Such source can be employed in optical coherence tomography (OCT) focused to dermatology. Therefore it is important to develop sources with emission wavelength that are not injurious to human skin. In the present work erbium doped fiber (EDF) was used owing that its emission wavelength (1550 nm) is adequate for this purpose. The most efficient way of achieving high power in a Q-Switch laser is optimizing all the parameters involved in the pulses generation, such as pumping power, active medium length and modulation frequency. The results show that using a fiber length of 7 meters is possible to get 10 μJ of energy, a peak power of 140 W, an average power of 27.5mW with temporal widths of 500 ns. The laser uses an acousto-optic device to modulate the internal loses inside the cavity. As highly reflecting mirrors, a Sagnac Interferometer and a Fiber Bragg Grating was employed.

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

    PubMed Central

    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. PMID:25949016

  16. LASERS: Small autonomous passively Q-switched Nd3+:YAG laser with a Cr4+:YAG Q switch emitting pulse trains

    NASA Astrophysics Data System (ADS)

    Buzinov, N. M.; Dmitriev, Valentin G.; Zabavin, V. N.; Kazakov, A. A.; Maslov, A. A.; Spitsyn, E. M.

    2007-04-01

    The energy and time characteristics of a passively Q-switched Nd3+:YAG laser with a Cr4+:YAG Q switch emitting pulse trains are studied and analysed theoretically. The description and technical parameters of a small autonomous laser with intracavity second-harmonic generation (ICSHG) in the pulse-train regime are presented. The laser provides a high total pulse-train energy for a relatively low peak power of a single pulse, stable operation in a wide temperature range, and has a small weight and size, which is convenient in operation. The enhanced reliability and stability of the laser operation are provided by its original technical design: the ICSHG scheme for type II phase matching without polarisers, the use of temperature-noncritical phase matching in KTP crystals, dust- and moisture-proof casing, and battery-operated pulsed power supply for the pump flashlamp.

  17. Laser lithotripsy with a Q-switched alexandrite laser system

    NASA Astrophysics Data System (ADS)

    Uebelacker, Walter

    1992-06-01

    The laser lithotripsy of ureter stones with the Alexan Triptor was introduced into urology in 1989. Pulsenergy, pulsewidth, wavelength, fiber performance, and endoscope performance are important parameters for effective stone disintegration.

  18. Q-switched laser in an SMS cavity for inhibiting nonlinear effects.

    PubMed

    Zhou, Jiaqi; Lu, Yi; He, Bing; Gu, Xijia

    2015-07-01

    In the design of high-power Q-switched fiber lasers, nonlinear effects often become barriers that prevent the scale up of pulse energy and peak power. New designs and components that could inhibit or suppress nonlinear effects are in high demand, particularly in all-fiber configurations. In this paper, we demonstrated a Q-switched Yb-doped fiber laser in a single-mode multimode single-mode (SMS) structure to inhibit fiber nonlinear effects. The laser-generated Q-switched pulses with a peak power close to 1 kW (pulse width and energy of 100 ns and 92 μJ, respectively). The output spectrum of this laser was compared with that of a Q-switched Yb-doped fiber laser built in a conventional configuration with similar output peak power. The results showed, for the first time to our knowledge, that the SMS Q-switched laser completely inhibited the stimulated Raman scattering and significantly reduced self-phase modulation. PMID:26193155

  19. Optical chopper Q-switching for flashlamp-pumped Er,Cr:YSGG lasers

    NASA Astrophysics Data System (ADS)

    Murphy, Francis J.; Arbabzadah, Emma A.; Bak, Alexey O.; Amrania, Hemmel; Damzen, Michael J.; Phillips, Chris C.

    2015-04-01

    We present a novel way of Q-switching a flashlamp-pumped, λ = 2.8 μm Er,Cr:YSGG laser, wherein a rotating polygon is used as an optical chopper. Single pulse energies of ~3.8 mJ were achieved with pulsewidths of ~305 ns. The scheme benefits from the simplicity of design, and, compared with other Q-switching methods, a reduction in losses and laser damage problems from intracavity components. We also investigate the optimization of the laser output through purging of the laser with nitrogen, and find a 29% increase in peak output energy.

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

    NASA Astrophysics Data System (ADS)

    Beyatli, Ersen; Sennaroglu, Alphan; Demirbas, Umit

    2013-03-01

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

  1. Ocular dynamics and visual tracking performance after Q-switched laser exposure

    NASA Astrophysics Data System (ADS)

    Zwick, Harry; Stuck, Bruce E.; Lund, David J.; Nawim, Maqsood

    2001-05-01

    In previous investigations of q-switched laser retinal exposure in awake task oriented non-human primates (NHPs), the threshold for retinal damage occurred well below that of the threshold for permanent visual function loss. Visual function measures used in these studies involved measures of visual acuity and contrast sensitivity. In the present study, we examine the same relationship for q-switched laser exposure using a visual performance task, where task dependency involves more parafoveal than foveal retina. NHPs were trained on a visual pursuit motor tracking performance task that required maintaining a small HeNe laser spot (0.3 degrees) centered in a slowly moving (0.5deg/sec) annulus. When NHPs reliably produced visual target tracking efficiencies > 80%, single q-switched laser exposures (7 nsec) were made coaxially with the line of sight of the moving target. An infrared camera imaged the pupil during exposure to obtain the pupillary response to the laser flash. Retinal images were obtained with a scanning laser ophthalmoscope 3 days post exposure under ketamine and nembutol anesthesia. Q-switched visible laser exposures at twice the damage threshold produced small (about 50mm) retinal lesions temporal to the fovea; deficits in NHP visual pursuit tracking were transient, demonstrating full recovery to baseline within a single tracking session. Post exposure analysis of the pupillary response demonstrated that the exposure flash entered the pupil, followed by 90 msec refractory period and than a 12 % pupillary contraction within 1.5 sec from the onset of laser exposure. At 6 times the morphological threshold damage level for 532 nm q-switched exposure, longer term losses in NHP pursuit tracking performance were observed. In summary, q-switched laser exposure appears to have a higher threshold for permanent visual performance loss than the corresponding threshold to produce retinal threshold injury. Mechanisms of neural plasticity within the retina and at

  2. Narrow-band tunable alexandrite laser with passive Q switching

    SciTech Connect

    Tyryshkin, I S; Ivanov, N A; Khulugurov, V M

    1998-06-30

    An alexandrite laser with a self-injection of narrow-band radiation into its cavity was developed. A Fabry - Perot interferometer and a diffraction grating were used as dispersive components in an additional cavity. The cavity was switched by an LiF crystal with F{sub 3}{sup -} colour centres. The laser generated a single pulse of {approx} 180 ns duration and of 1.5 mJ energy, and with a spectrum 5 x 10{sup -3} cm{sup -1} wide. The laser emitted in the spectral range 720 - 780 nm. (lasers, active media)

  3. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber

    PubMed Central

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-01-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a ‘Yin-Yang’ all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser. PMID:27063511

  4. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber.

    PubMed

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-01-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a 'Yin-Yang' all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser. PMID:27063511

  5. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber

    NASA Astrophysics Data System (ADS)

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; Alaraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-04-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a ‘Yin-Yang’ all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser.

  6. A compact and efficient four-wavelength Q-switched Nd:YAP laser

    NASA Astrophysics Data System (ADS)

    Huang, C. H.; Zhang, G.; Wei, Y.; Zhu, H. Y.; Huang, L. X.

    2010-04-01

    In this paper, a four-wavelength electro-optic (E-O) Q-switched solid-state laser system was presented. This laser system only use one Nd:YAP laser crystal, which irradiates 1079.5 nm and 1341.4 nm fundamental wavelengths. Both of these wavelength lasers and their second harmonic generation (SHG) compose a four-wavelength Nd:YAP Q-switched laser. The Q-switched output energies of 277 mJ for 1079.5 nm and 61 mJ for 539.8 nm and that of 190 mJ for 1341.4 nm and 51 mJ for 670.7 nm wavelengths were achieved. The pulse durations of 1079.5 and 539.8 nm lasers and that of 1341.4 and 670.7 nm lasers are 20 and 40 ns, respectively. Due to this laser system has the larger chance and convenience for selecting the wavelengths and operation modes by moving a stepping motor and controlling the Q-switched devices, it will broaden applications in the fields of laser cosmetology, dermatotis therapy, material processing and laser display etc.

  7. Er/Yb glass laser with compact mechanical Q-switch

    NASA Astrophysics Data System (ADS)

    Cole, Brian; Hough, Nathaniel; Hays, Alan; Nettleton, John; Goldberg, Lew

    2016-03-01

    We describe a compact, side-pumped, Er/Yb glass laser with a low cost mechanical Q-switch. The Q-switch uses a mirror or reflecting prism mounted on a cantilever resonant spring that is driven by a small electromagnetic coil. The demonstrated laser used a 5 mm long Er/Yb glass gain element, and was side-pumped by a 940 nm, 5 mm wide diode bar generating up to 100 W peak power. Target energies of 3mJ have been realized in a near-diffraction limited mode, with pulse widths of 15-25ns, and an optical-to-optical efficiency of greater than 2%. The mechanical Q-switch assembly was fully athermalized via mounting a displacing porro reflector to the cantilever spring, where a 2.5mJ laser was observed to operate with less than 5% variance over -35°C to+60°C.

  8. Cr 4+: GSGG saturable absorber Q-switch for the ruby laser

    NASA Astrophysics Data System (ADS)

    Chen, W.; Spariosu, K.; Stultz, R.; Kuo, Y. K.; Birnbaum, M.; Shestakov, A. V.

    1993-12-01

    Cr 4+: GSGG has been utilized for the first time to provide a saturable absorber Q-switch for the ruby laser. Single output pulse operation (100 mJ and 27 ns duration) with efficiencies relative to the free-running ruby laser operation of 25-30% was routinely obtained.

  9. SOLITONS AND OPTICAL FIBERS: Self-Q-switched ytterbium-doped cladding-pumped fibre laser

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Li, Lifei; Zheng, Xinliang; Jin, Chenjie; Qi, Mei; Chen, Xiaoming; Ren, Zhaoyu; Bai, Jintao; Sun, Zhipei

    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 M2 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.

  11. One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Modlin, Ed A.; Singh, Upendra N.; Kavaya, Michael J.; Chen, Songsheng; Bai, Yingxin; Petzar, Pual J.; Petros, Mulugeta

    2005-01-01

    Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality.

  12. High average power of Q-switched Tm:YAG slab laser

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    A laser-diode end-pumped Tm:YAG single crystal slab laser in acousto-optic Q-switched operation was demonstrated. For Q-switched operation, the average output power of 20.7 W at 1 kHz was achieved under the absorbed pump power of 83.6 W, corresponding to the slope efficiency of 36.1%, the shortest pulse width of 84 ns and the maximum pulse energy of 20.7 mJ with peak power of 250 kW were obtained.

  13. Numerical simulation and optimization of passively q-switched erbium microchip lasers

    NASA Astrophysics Data System (ADS)

    Belghachem, Nabil; Mlynczak, Jarslow

    2015-08-01

    In this article we present a procedure of optimization of passively q-switched erbium microchip lasers. The procedure is based on the rate equation model, validated by comparing the numerical results to the experimental results of pulse generation in different types of erbium/ytterbium glass microchips q-switched by Co2+ : MgAl2O4 saturable absorber. Some Degnan’s optimization limitations in case of microchip lasers were also shown and the reabsorbtion cross section of erbium glass was also estimated.

  14. Wavelength switchable graphene Q-switched fiber laser with cascaded fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Wu, Man; Chen, Shuqing; Chen, Yu; Li, Ying

    2016-06-01

    We have demonstrated a wavelength switchable graphene Q-switched fiber laser with two cascaded fiber Bragg gratings. Stable Q-switching operation with central wavelength 1542.9 nm (1543.7 nm), repetition rate 28.4 kHz (22.58 kHz), and pulse duration 2.16 μs (2.65 μs) can be obtained by adjusting the intra-cavity birefringence. Moreover, stable dual-wavelength operation with wavelength spacing 0.8 nm can also be observed. The cascaded fiber gratings combined with the graphene saturable absorber provide a simple and feasible way to get versatile pulsed fiber laser.

  15. Passive Q-Switching Laser Performance of Yb:YVO4 Crystal

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Hong; Chen, Xiao-Wen; Han, Wen-Juan; Kong, Wei-Jin; Liu, Jun-Hai

    2014-12-01

    We report on the passive Q-switching laser performance of Yb:YVO4 crystal. Utilizing a Cr4+:YAG crystal plate as the saturable absorber, which is of an initial transmission as high as 99.3%, we demonstrate a stable passively Q-switched laser operation at 1017.2 nm, producing an average output power of 0.87 W at a pulse repetition rate of 71.4 kHz, with a slope efficiency of 30%. The resulting pulse energy, duration, and peak power are 12.2 μJ, 87 ns, and 0.14 kW, respectively.

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

    PubMed

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

    2015-08-10

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

  17. 980-nm Q-switched photonic crystal fiber laser by MoS2 saturable absorber

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  18. The effect of the depth of single longitudinal mode modulation in Q-switching pre-Pr3+:YLF laser

    NASA Astrophysics Data System (ADS)

    Qing-Song, Li; Ling-Xi, Zhu; Xi-He, Zhang; Yuan, Dong; Yong-Ji, Yu; Guang-Yong, Jin

    2016-08-01

    The single longitudinal mode (SLM) can be obtained under the condition of Q-switching pre-lase. In this paper, the model of Q-switching pre-lase is firstly established. Taking the Pr3+:YLF laser as an example, the process of Q-switching pre-lase is simulated and optimized, then the optimized parameters and best output characteristics under different depth of SLM modulation are obtained. Comparing with the normal Q-switching laser, the SLM pulse energy can reach to 79.29%, the pulse width exceeds 16.45% and the depth of SLM modulation get to be 20. The results show that the Q-switching pre-lase output characteristics can be effected obviously by the SLM modulation depth, and the pulse energy and pulse width can be close to the normal Q-switching laser as long as the depth of SLM modulation is optimized.

  19. Wavelength-selective, sequential Q-switching laser cavity

    NASA Technical Reports Server (NTRS)

    Allario, F.; Lucht, R. A.

    1974-01-01

    Single-frequency continuous output of laser is converted into series of high-power laser pulses at high repetition rates. Applications include pollutant detection by absorption, laser gain measurements at discrete wavelengths, laser propagation measurement, and laser plasma diagnostics.

  20. Injection seeding of a Q-switched alexandrite laser: Study of frequency stabilization

    NASA Technical Reports Server (NTRS)

    Brown, Lamarr A.

    1992-01-01

    AlGaAs diode lasers were used to injection seed a pulsed Q-switched alexandrite laser which produces a narrowband of radiation. Injection seeding is a method for achieving linewidths of less than 500 mega-Hz in the output of the broadband, tunable solid state laser. When the laser was set at a current of 59.8 milli-A and a temperature of 14.04 C, the wavelength was 767.6 nano-m. The Q-switched alexandrite laser was injection seeded and frequency stabilization was studied. The linewidth requirement was met, but the stability requirement was not due to drifting in the feedback voltage. Improvements on injection seeding should focus on increasing the feedback voltage to the laser diode, filtering the laser diode by using temperature controlled narrowband filters, and the use of diamond (SiC) grating placed inside the alexandrite laser's resonator cavity.

  1. Performance of passive Q-switched solar-pumped high-power Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Noter, Yoram; Naftali, Nir; Pe'er, Idit L.; Yogev, Amnon; Lando, Mordechai; Shimony, Yehoshua

    1997-09-01

    Q-switched, solar-pumped, high power Nd:YAG lasers are attractive for a variety of applications requiring high instantaneous peak power density. The Q-switching can be obtained by an acousto-optic, electro-optic or passive device. Passive Q-switching seems an excellent choice for space as well as for other applications since it neither requires an external driver nor an electrical power supply. In recent years Cr+4:YAG single crystals were extensively used as passive Q-switches for flashlamp-pumped high power Nd:YAG lasers, demonstrating their superior thermal superior thermal characteristics and durability. In this work we report the first operation of passive Q- switched, solar-pumped, high power Nd:YAG lasers. The concentrated solar energy for he optical pumping of the laser was obtained by a 3-stage combination of imaging and non-imaging optics. It included: i) Weizmann Institute solar tower heliostats, ii) 3D compound parabolic concentrator, and iii) 2D compound parabolic concentrator in which the laser rod was placed. 72 mm long laser rods with either 3 mm or 4 mm diameter were used. The passive Q-switch was made from a Cr$=+4):YAG single crystal having a low- intensity transmission of 72 percent at 1.06 (mu) . Its rear surface was coated by a high reflectivity coating, serving as the rear mirror of the cavity. Output coupling mirrors with various reflectivities were used. The passive Q-switch demonstrated excellent durability and reliability during all the experiments. Repetition rates of 6-39 kHz were measured, showing higher repetition rates at higher laser power levels. The pulses demonstrated shorter full width at half maximum (FWHM) time for higher laser power elves, and the FWHM time range was 190-310 nsec. The maximal measured average power was 14 W. Thermal lensing was measured as a function of the absorbed solar power in the laser rod. It is estimated that laser peak power densities of approximately 100 kW/cm2 were achieved in the experiments. It is

  2. Passively Q-switched high-energy all-solid-state holographic Nd:YAG laser with a multiloop cavity

    NASA Astrophysics Data System (ADS)

    Lebedev, V. F.; Pogoda, A. P.; Boreysho, A. S.; Smetanin, S. N.; Fedin, A. V.

    2015-02-01

    A high-energy, high-beam-quality laser based on a single Nd:YAG rod with laser diode side-pumping and multiloop self-adaptive reciprocal cavity is presented. The optimized laser cavity geometry allowed to change the laser oscillation from single 200-ns self-Q-switched pulse followed by low-intensity free-running lasing to repetitive high-intensive pulses by periodically writing and erasing holographic gain gratings in the active Nd:YAG medium. The intensified self-Q-switching pulse train oscillation was realized by the interaction with a diffusely reflecting target placed in the focal plane of a lens at the laser output. Effects of shortening of the repetitive laser pulses down to 70-ns duration, stabilization of the pulse repetition period (~ 5 μs), and mode-locking temporal modulation of the pulses were observed. The use of a passive F2-:LiF Q-switch resulted in stable giant pulse train oscillation with total output energy of up to 0.43 J, individual pulse energy of 50 mJ, and its peak power of 4 MW at the individual pulse duration of 12 ns.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    A compact frequency-modulation Q-switched single-frequency fiber laser is demonstrated at 1083 nm. The short linear resonant cavity consists of a 12 mm long homemade Yb3+-doped phosphate fiber and a pair of fiber Bragg gratings (FBGs) in which the Q-switching and the frequency excursion is achieved by a tensile-induced period modulation. Over 375 MHz frequency-tuning range is achieved with a modulation frequency varying from tens to hundreds of kilohertz. The highest peak power of the output pulse reaching 6.93 W at the repetition rate of 10 kHz is obtained.

  4. Diode pumped CW and passively Q-switched Nd:LGGG laser at 1062 nm

    NASA Astrophysics Data System (ADS)

    Yang, H.; Jia, Z. T.; Zhang, B. T.; He, J. L.; Liu, S. D.; Yang, Y.; Tao, X. T.

    2012-05-01

    We report a Nd:LGGG laser at 1062 nm in the operations of the continuous-wave (CW) and passively Q-switching. The maximum CW output power of 5.62 W was obtained, corresponding to an optical-to-optical conversion efficiency of 49.0% and slope efficiency of 55.9%. By using Cr4+:YAG with initial transmission of 94% as the saturable absorber, for the first time, we got the maximum passively Q-switched output power of 1.21 W, accompanied with a highest pulse repetition rate of 27.1 kHz and a shortest pulse width of 9.1 ns.

  5. Graphene Q-switched Ho(3+)-doped ZBLAN fiber laser at 1190  nm.

    PubMed

    Liu, Shujing; Zhu, Xiushan; Zhu, Gongwen; Balakrishnan, Kaushik; Zong, Jie; Wiersma, Kort; Chavez-Pirson, Arturo; Norwood, R A; Peyghambarian, N

    2015-01-15

    We report Q-switched pulse operation of holmium (Ho(3+))-doped ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF (ZBLAN) at ∼1190  nm in an all-fiber ring laser by using a fiber-optic graphene saturable absorber, which was fabricated by depositing graphene onto the flat surface of a side-polished D-shaped fiber. Stable Q-switched operation was established at a pump power of 180 mW with a repetition rate of 24 kHz and pulse width of 5.7 μs. When the pump power was increased to 1125 mW, 0.44 μJ Q-switched pulses with a repetition rate of 111 kHz and a pulse width of 0.8 μs were generated. PMID:25679830

  6. Five simultaneously Q-switch mode-locked passive laser modulators

    NASA Astrophysics Data System (ADS)

    Chen, Junewen

    2007-02-01

    Five types of passive Q-switched as well as simultaneously Q-switch mode-locked modulators: plastic dye sheets ( Kodak 9850 cellulose acetate dye sheets), lithium fluoride crystals containing F II - color centers ( LiF: F II -), chromium doped yttrium aluminum garnet crystals ( Cr 4+:YAG), ionic color filter glass ( Schott RG1000 color filter glass) and the single crystal semiconductor wafers ( GaAs, Fe doped InP, Zn doped InP, S doped InP, etc.) used for the modulation of the Nd:hosted(Nd:YAG, Nd:YVO 4, and Nd:LSB) lasers have been investigated in detail in our researches. We have also investigated into the applications of the Q-switch mode-locked pulses train for the development of higher resolution solid state laser range finder. We will also present the high accuracy laser ranging results, the micro-motor that driven mechanical parts from the stepping digital ranging readout, to precisely control the best focus of a miniature zoom lens modular. The core simultaneously Q-switch mode-locked modulators microchip laser is the key part of our automatic optical inspection system.

  7. Spectral and temporal control of Q-switched solid-state lasers using intracavity MEMS

    NASA Astrophysics Data System (ADS)

    Paterson, A.; Bauer, R.; Li, R.; Clark, C.; Lubeigt, W.; Uttamchandani, D.

    2016-03-01

    Active control of the spectral and temporal output characteristics of solid-state lasers through use of MEMS scanning micromirrors is presented. A side-pumped Nd:YAG laser with two intracavity scanning micromirrors, enabling Q-switching operation with controllable pulse duration and pulse-on-demand capabilities, is investigated. Changing the actuation signal of one micromirror allows a variation of the pulse duration between 370 ns and 1.06 μs at a pulse repetition frequency of 21.37 kHz and average output power of 50 mW. Pulse-on-demand lasing is enabled through actuation of the second micromirror. To our knowledge this is the first demonstration of the use of multiple intracavity MEMS devices as active tuning elements in a single solid-state laser cavity. Furthermore, we present the first demonstration of control over the output wavelength of a solid-state laser using a micromirror and a prism in an intracavity Littman configuration. A static tilt actuation of the micromirror resulted in tuning the output wavelength of an Yb:KGW laser from 1024 nm to 1031.5 nm, with FWHM bandwidths between 0.2 nm and 0.4 nm. These proof-of-principle demonstrations provide the first steps towards a miniaturized, flexible solid-state laser system with potential defense and industrial applications.

  8. Cavity length dependence of mode beating in passively Q-switched Nd-solid state lasers

    NASA Astrophysics Data System (ADS)

    Zameroski, Nathan D.; Wanke, Michael; Bossert, David

    2013-03-01

    The temporal intensity profile of pulse(s) from passively Q-switched and passively Q-switched mode locked (QSML) solid-state lasers is known to be dependent on cavity length. In this work, the pulse width, modulation depth, and beat frequencies of a Nd:Cr:GSGG laser using a Cr+4:YAG passive Q-switch are investigated as function cavity length. Measured temporal widths are linearly correlated with cavity length but generally 3-5 ns larger than theoretical predictions. Some cavity lengths exhibit pulse profiles with no modulation while other lengths exhibit complete amplitude modulation. The observed beat frequencies at certain cavity lengths cannot be accounted for with passively QSML models in which the pulse train repetition rate is τRT-1, τRT= round-trip time. They can be explained, however, by including coupled cavity mode-locking effects. A theoretical model developed for a two section coupled cavity semiconductor laser is adapted to a solid-state laser to interpret measured beat frequencies. We also numerically evaluate the temporal criterion required to achieve temporally smooth Q-switched pulses, versus cavity length and pump rate. We show that in flash lamp pumped systems, the difference in buildup time between longitudinal modes is largely dependent on the pump rate. In applications where short pulse delay is important, the pumping rate may limit the ability to achieve temporally smooth pulses in passively Q-switched lasers. Simulations support trends in experimental data. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  9. Frequency tuning characteristics of a Q-switched Co:MgF2 laser

    NASA Technical Reports Server (NTRS)

    Lovold, S.; Moulton, P. F.; Killinger, D. K.; Menyuk, N.

    1985-01-01

    A tunable Q-switched Co:MgF2 laser has been developed for atmospheric remote sensing applications. Frequency tuning is provided by a quartz etalon and a specially designed three-element birefringent filter covering the whole gain bandwidth of the Co:MgF2 laser. The laser has good temporal and spectral characteristics, with an emission linewidth of approximately 3 GHz (0.1 per cm).

  10. Passively Q-switched microchip lasers based on Yb:YAG/Cr4+:YAG composite crystal

    NASA Astrophysics Data System (ADS)

    Ren, Yingying; Dong, Jun

    2014-02-01

    Efficient passively Q-switched microchip laser based on Yb:YAG/Cr4+:YAG composite crystal has been demonstrated under high brightness single-emitter laser-diode pumping. Maximum average output power of 1.5 W was obtained when the absorbed pump power was 3.65 W, the corresponding optical-to-optical efficiency was over 41%. The slope efficiency was 52.3%. The effect of the cavity length on the performance of Yb:YAG/Cr4+:YAG composite crystal passively Q-switched microchip lasers was investigated. Laser pulses at 1030 nm with pulse width of 466 ps and peak power of 91 kW were achieved with cavity length of 1.7 mm, while laser pulses with pulse width of 665 ps and peak power of 79 kW were obtained with cavity length of 3.7 mm.

  11. Q-switching of mid-infrared Er:YAG laser and its radiation delivery system

    NASA Astrophysics Data System (ADS)

    Jelinkova, Helena; Koranda, Petr; Nemec, Michal; Sulc, Jan; Cech, Miroslav; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2004-09-01

    Q-switching of mid-infrared Er:YAG laser was obtained with an electro-optical shutter. For that the LiNbO3 Pockels cell was used in transversal quarter-wave arrangement with the Brewster angle cut faces used as a polarizer. Parameters and dependences of this Q-switched system were investigated, i.e. a pulse length and generated pulse energy, delay between switching of flashlamp and Q-switch circuit, high voltage applied on Pockels cell were measured and optimized. The resulted giant pulse length and energy was 60 ns and 55 mJ, respectively. This generated pulse was obtained for the applied voltage around 1.4 kV and for the optimum delay value 450 us. Problem of mid-infrared giant pulse delivery, which is needed for various technological applications, was solved by a specially designed cyclic olefin polymer coated silver hollow glass (COP/Ag) waveguide. Parameters of this waveguide were: diameter 700/850 um and length 1 m. The measured transmission was 74 % which corresponded to delivered intensity 86 MW/cm2. Q-switched Er:YAG laser radiation in connection with this special delivery system gives a possibility of the surgical treatment in many medicine branches, for example ophthalmology, urology or dentistry.

  12. Pulse synchronisation in passively Q-switched lasers emitting at 1.053 and 1.064 {mu}m

    SciTech Connect

    Bagdasarov, V Kh; Denisov, N N; Malyutin, A A; Chigaev, I A

    2009-10-31

    Pulse synchronisation with an accuracy of no worse than {+-}5 ns is demonstrated in passively Q-switched neodymium phosphate glass and Nd:YAG lasers. Two operating regimes are realised: the 'sub-threshold' regime (when the slave Nd:YAG laser does not generate a giant pulse if its passive Q switch is not irradiated by the master Nd:glass laser) and the 'above-threshold' regime (when the pulse irradiating the passive Q switch of the slave laser advances its generation). (control of laser radiation parameters)

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

    PubMed

    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. PMID:26974625

  14. Passively Q-switched nd:YAG laser via a WS2 saturable absorber

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Wang, Yonggang; Duan, Lina; Li, Lu; Sun, Hang

    2016-05-01

    In this work, we report a passively Q-switched Nd:YAG laser at 1064 nm by using WS2 solution as the saturable absorber (SA). The WS2 solution with different concentrations (0.25, 0.5, and 1 mg/ml) were fabricated by the liquid-phase-exfoliated method and injected into quartz cells. Such liquid absorbers have the virtues of adjustable optical absorption, high heat dissipation and non-contact damage. By inserting those WS2 solutions in the laser cavity, stable Q-switched laser operations were obtained. The corresponding pulse duration as short as 922 ns was obtained. The result shows that the WS2 material can be act as absorber for solid-state lasers.

  15. Analysis of related factor of pigment alteration after Q-switched laser treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Xu, Cai Xia; Ding, Yang Feng; Tan, Yi Wen

    2005-07-01

    To explore the related factors of pigment alteration after the Q-switched laser treatment. After the Q-switched laser treatment, the side effects in patients were observed, recorded and analyzed. The results showed that the incidence of pigment alteration is directly related to age (OR1=2.519, confidence interval 0.996-6.366; OR2=2.519, confidence interval 0.978-6.488; OR3=8.311, confidence interval 3.312-29.695). Besides, the pigment alteration is also correlated to the skin types, but not to gender, kind of diseases, parts of body, intensity of ultraviolet radiation, character of work, wavelength of laser and the energy of laser. Older patient is easier to have pigment alteration than younger patient. Pigment alteration may be obvious in a pigmented individual than a lightly pigmented individual.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Generation of single longitudinal mode in a pulsed passively Q -switched Nd:YAG laser

    SciTech Connect

    Hariri, A.; Soltanmoradi, F.; Nayeri, M. )

    1990-08-01

    It is shown that a single longitudinal mode in a passively {ital Q}-switch Nd:YAG laser can be obtained by adjusting an intracavity saturable absorber gelatin film (BDN) to work as a mirror in a three-mirror Fabry--Perot resonator. With a 0.13-mm-thick gelatin film of 40% unsaturated transmission, a temporally smooth single-laser pulse of {similar to}10 ns duration has been obtained.

  18. Fast recharge circuit for q-switched lasers

    NASA Technical Reports Server (NTRS)

    Hansen, R. L.

    1973-01-01

    Cavity-dumped lasers employ electrooptic-effect cell to alternately block and release laser pulse. Cell requires high-speed switching circuit that can apply and remove high voltage. Solid-state circuit employs complementary transistor switches which can switch at rates greater than 5 kHz, eliminate warmup time, provide variable voltage wave-form, and allow polarity reversal.

  19. Passive Q-switching of microchip lasers based on Ho:YAG ceramics.

    PubMed

    Lan, R; Loiko, P; Mateos, X; Wang, Y; Li, J; Pan, Y; Choi, S Y; Kim, M H; Rotermund, F; Yasukevich, A; Yumashev, K; Griebner, U; Petrov, V

    2016-06-20

    A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr2+:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm2, respectively. When using Cr2+:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz. PMID:27409113

  20. The design of passively Q-switched solid-state lasers

    NASA Astrophysics Data System (ADS)

    Xiao, Guohua

    The passively Q-switched laser has been of intense interest because it is generally simple, convenient, and requires a minimum of intracavity elements and no external high voltage or RF drivers. Z-scan technique was used to obtain more realistic values of the ground and excited state absorption cross sections of Cr:YAG, one of the most important solid state saturable absorbers. Other spectroscopic research revealed that Cr:YAG performs stably over the wide temperature range from -70 to +80°C. A generalized model of a passively Q-switched laser was developed. It enables performance optimization including general cases in which the saturable absorber exhibits both ground and excited state absorption at the laser wavelength. Based on the theory, we built and tested a Nd:glass laser passively Q-switched by a Cr4+:YAG crystal and found excellent agreement with our model. The model was then extended to the case where an optical parametric oscillator (OPO) is contained inside the passively Q-switched laser cavity. In such a laser there is no output at the fundamental or pump wavelength. When the OPO signal field begins to build up, it acts as a loss for the pump and cavity dumps the pump resonator. The extended model describes the complicated interactions between the fundamental laser gain medium, saturable absorber, fundamental laser cavity, and OPO cavity. The model developed enables one to select OPO parameters which optimize the system's performance. Application of the model to a very compact, lightweight, eye-safe laser range finder operating at 1.54 μm will also be presented. Many applications demand lasers to be operated over a wide temperature range (-55-75°C). Efforts were dedicated to obtaining information on the temperature dependence of the emission cross section of Nd,Cr:GSGG and the optical properties of certain laser resonator optics. The data serve as input parameters to the models to design passively Q-switched laser systems with predictable

  1. Environmental testing of a Q-switched Nd:YLF laser and a Nd:YAG ring laser

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.

    1991-01-01

    A Q-switched Nd:YLF laser (model 110-02) and a Nd:YAG ring laser (model 120-04) from Lightwave Electronics were subjected to thermal and vibration tests similar to what can be expected during launch and flight on a spacecraft. Even though these lasers were not designed for space flight, environmental tests were performed to identify major design weaknesses. Laser performance (output power, energy, pulsewidth, lasing threshold etc.) were measured prior to and after thermal vibration tests. Average output power of the Q-switched laser degraded 15-20 percent after thermal tests and an additional 20-25 percent after vibration tests. Post diagnostic tests revealed that degradation of the Q-switched laser was due to misalignment of pump focusing optics and the laser cavity.

  2. Continuous-wave and passively Q-switched cladding-pumped planar waveguide lasers.

    PubMed

    Beach, R J; Mitchell, S C; Meissner, H E; Meissner, O R; Krupke, W F; McMahon, J M; Bennett, W J; Shepherd, D P

    2001-06-15

    Greater than 12 W of average output power has been generated from a diode-pumped Yb:YAG cladding-pumped planar waveguide laser. The laser radiation developed is linearly polarized and diffraction limited in the guiding dimension. A slope efficiency of 0.5 W/W with a peak optical-optical conversion efficiency of 0.31 W/W is achieved. In a related structure, greater than 8 W of Q -switched average output power has been generated from a Nd:YAG cladding-pumped planar waveguide laser by incorporation of a Cr(4+): YAG passive Q switch monolithically into the waveguide structure. Pulse widths of 3 ns and pulse-repetition frequencies as high as 80 kHz have been demonstrated. A slope efficiency of 0.28 W/W with a peak optical-optical conversion efficiency of 0.21 W/W is achieved. PMID:18040479

  3. Dual-wavelength passively Q-switched Nd:GYSGG laser by tungsten disulfide saturable absorber.

    PubMed

    Gao, Y J; Zhang, B Y; Song, Q; Wang, G J; Wang, W J; Hong, M H; Dou, R Q; Sun, D L; Zhang, Q L

    2016-06-20

    A dual-wavelength passively Q-switched Nd:GYSGG laser using vacuum evaporating tungsten disulfide (WS2) as a saturable absorber was demonstrated for the first time to the best of our knowledge. The WS2 saturable absorber was prepared simply by evaporating nanometer WS2 powders onto a quartz substrate in a vacuum. By inserting the WS2 saturable absorber into the laser cavity, stable Q-switched laser operation was achieved with a maximum average output power of 367 mW, a pulse repetition rate of 70.7 kHz, the shortest pulse width of 591 ns, and pulse energy of about 1.05 μJ. By vacuum evaporation method, a high-quality WS2 saturable absorber can be produced, and it seems to be a suitable method for fabrication of 2D transition metal dichalcogenides. PMID:27409120

  4. The output beam quality of a Q-switched Nd:glass slab laser

    NASA Technical Reports Server (NTRS)

    Reed, Murray K.; Byer, Robert L.

    1990-01-01

    The authors have constructed and tested a flashlamp pumped, Q-switched, Nd:glass zigzag slab laser. The thermally induced optical distortion through the slab is minimized by uniform pumping and cooling and the use of corrective pump shields at the slab ends. The laser spatial output for Q-switched resonators has been measured and modeled. It is shown that a larger aperture planar oscillator has an output divergence many times above the diffraction limit. Operation as a one-dimensional unstable resonator in the wide direction of the slab allows the efficient extraction of energy in a high-quality beam. Near-diffraction-limited laser output of 5 J at 4 Hz is achieved with a resonator that includes an intracavity telescope to correct for residual defocusing in the thin direction of the slab.

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

    SciTech Connect

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

    1990-09-15

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

  6. A semi-analytical approach for evaluating effects of amplified spontaneous emission on characteristics of Q-switched lasers

    SciTech Connect

    Razzaghi, D; Hajiesmaeilbaigi, F; Ruzbehani, M

    2012-08-31

    Possible effects of amplified spontaneous emission on output pulse characteristics of a Q-switched laser are discussed within the framework of a semi-analytical approach. It is shown that output energy decreases almost exponentially with average path length of the spontaneously emitted photons which in turn depends on geometrical specification and active medium properties as well as on optical finishing of the surfaces (for solid-state lasers). Optimal coupling dependence on the average path length is also investigated and shown to increase with average path length increment. (control of laser radiation parameters)

  7. Cr{sup 4+}:YAG as passive Q-switch and Brewster plate in a pulsed Nd:YAG laser

    SciTech Connect

    Shimony, Y.; Burshtein, Z.; Kalisky, Y.

    1995-10-01

    The authors demonstrate the performance of a Nd:YAG laser, passively Q-switched with a Cr{sup 4+}:YAG plate, which plays the double role of a passive Q-switch ad a Brewster plate. The Brewster plate configuration contributes an intracavity loss of approximately 3.2 {times} 10{sup {minus}3} cm{sup {minus}1} along the cavity length. Losses contributed by the active Cr{sup 4+} ions in the plate relate to their excited state absorption. A freshly measured transmission saturation curve of Cr{sup 4+}:YAG suggests a ground state absorption cross section {sigma}{sub gs} = (8.7 {+-} 0.8) {times} 10{sup {minus}19} cm{sup 2}, and an excited state absorption cross section {sigma}{sub es} = (2.2 {+-} 0.2) {times} 10{sup {minus}19} cm{sup 2} of the Cr{sup 4+} ions at {lambda} = 1,064 nm.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Taylor, C.R.; Gange, R.W.; Dover, J.S.; Flotte, T.J.; Gonzalez, E.; Michaud, N.; Anderson, R.R. )

    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.

  10. All-solid-state passively Q -switched mode-locked Nd-doped fiber laser

    SciTech Connect

    Zenteno, L.A.; Po, H.; Cho, N.M. )

    1990-01-15

    We report the generation of {ital Q}-switched mode-locked pulses from a Nd-doped fiber laser that uses a solid-state solution of BDN-I dye as the saturable absorber and is pumped by a GaAlAs laser diode. For an absorbed pump power of 110 m W, pulses of 8-nsec duration at a repetition rate of 14 MHz can be generated under an 800-nsec-wide {ital Q}-switched envelope at a repetition rate of 100 kHz, yielding an average output power of 8 m W near 1.06 {mu}m. This corresponds to approximately 9 W of peak power in the main mode-locked pulse.

  11. Tunable Q-switched fiber laser using zinc oxide nanoparticles as a saturable absorber.

    PubMed

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

    2016-06-01

    Nanomaterials have ignited new interest due to their distinctive electronic, mechanical, and optical properties. Zinc oxide nanostructures are fabricated into thin film and then inserted between two fiber ferrules to act as a saturable absorber (SA). The modulation depth and insertion loss of the SA are 5% and 3.5 dB, respectively. When the ZnO-SA is incorporated into the laser cavity, a stable Q-switched pulse tunable from 1536 to 1586 nm (50 nm range) with pulse energy up to 46 nJ was observed. Our result suggests that ZnO is a promising broadband SA to generate passively Q-switched fiber lasers. PMID:27411175

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

    SciTech Connect

    Li, Lifei; Jin, Chenjie; Qi, Mei; Chen, Xiaoming; Ren, Zhaoyu E-mail: rzy@nwu.edu.cn; Zheng, Xinliang E-mail: rzy@nwu.edu.cn; Bai, Jintao; Sun, Zhipei

    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.

  13. Dual-wavelength passively q-switched single-frequency fiber laser.

    PubMed

    Zhang, Yuanfei; Yang, Changsheng; Feng, Zhouming; Deng, Huaqiu; Peng, Mingying; Yang, Zhongmin; Xu, Shanhui

    2016-07-11

    We propose a compact dual-wavelength Q-switched single-frequency fiber laser based on a 17-mm-long home-made highly Er3+/Yb3+ co-doped phosphate fiber (EYDPF) and a semiconductor saturable absorber mirror (SESAM). The short cavity length and a polarization-maintaining fiber Bragg grating (PM-FBG) ensure that only one longitudinal mode is supported by each reflection peak. The maximum pulse energy of more than 34.5 nJ was realized with the shortest pulse duration of 110.5 ns and the Q-switched fiber laser has a repetition rate reaching over 700 kHz with a temporal synchronization of pulses at two wavelengths. Besides, the optical signal-to-noise ratio (OSNR) of larger than 64.5 dB was achieved. PMID:27410881

  14. Clinical effects of iridectomy performed by laser YAG Nd+3 Q switch

    NASA Astrophysics Data System (ADS)

    Kecik, Tadeusz; Zydecki, Miroslaw

    1995-03-01

    Clinical effects of iridectomy performed by the use of laser Yag Nd+3-Q-switch on 38 patients treated for intra-ocular pressure increase were analyzed. In 32 cases primary glaucoma was diagnosed. In 11 cases secondary glaucoma was caused by pupil blocking. Pressure normalization was obtained in 27 cases (71%). In the remaining 11 patients pressure decreasing was acquired but at the same time administration of antiglaucoma medicines was indispensable. Time of observation took from 4 weeks to 3 years.

  15. Q-switched Tm-doped fiber lasers using dynamic microbends in oval-coating fibers

    NASA Astrophysics Data System (ADS)

    Araki, S.; Kimpara, K.; Tomiki, M.; Sakata, H.

    2013-06-01

    We present Q-switched pulse generation in a thulium-doped fiber laser by inducing a piezoelectric-driven microbend into an oval-coating fiber. The oval-coating fiber is made of a single-mode fiber in which an acrylic coating is flattened by thermal pressing. A pulse peak power of 1.45 W is obtained with a pump power of 139 mW.

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

    PubMed

    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. PMID:23722799

  17. Efficient energy extraction from a diode-pumped Q-switched Tm,Ho:YLiF4 laser

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  18. Azimuthally polarized, passively Q-switched Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Zou, Lin; Yao, Yao; Han, Xiahui; Liu, Jinyu; Xu, Yun; Li, Jianlang

    2015-11-01

    An azimuthally polarized and passively Q-switched ytterbium-doped fiber laser was demonstrated. With the involvement of a single lens inside the laser resonator, a birefringent crystal was used as the polarization discriminator, and a Cr4+:YAG crystal acted as the saturable absorber and also the output coupler. For the simplicity and low optical loss of the resonator cavity, this fiber laser emitted azimuthally polarized pulse with a high slope efficiency of 72.6% and high average power of 4.11 W. The laser pulse had 132-ns duration and 112-kHz repetition rate at the absorbed pump power of 6.40 W.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed

    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. PMID:27409862

  1. Generation of 1.6 ns Q-switched pulses based on Yb:YAG/Cr:YAG microchip laser

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The highly-stable Q-switched longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1031 nm, was designed and realized. This laser was based on monolith crystal which combines in one piece an active laser part (YAG crystal doped with Yb3+ ions, 10 at.% Yb/Y, 3mm long) and saturable absorber (YAG crystal doped with Cr3+ ions, 1.36mm long). The diameter of the diffusion bonded monolith was 3 mm. The initial transmission of the Cr:YAG part was 90% @ 1031 nm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces. The pump mirror (HT for pump radiation, HR for generated radiation) was placed on the Yb:YAG part. The output coupler with reflection 55% for the generated wavelength was placed on the Cr3+-doped part. Q-switched microchip laser was tested under CW diode pumping. For longitudinal pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA= 0.22) laser diode, operating at wavelength 968 nm, was used. The laser threshold was 3.3W. The laser slope efficiency calculated for output mean power in respect to incident CW pumping was 17%. The wavelength of linearly polarized laser emission was fixed to 1031 nm. The generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length was equal to 1.6 ns (FWHM). This value was mostly stable and independent on investigated pumping powers in the range from the threshold up to 9.3W. The single pulse energy was linearly increasing with the pumping power. Close to the laser threshold the generated pulse energy was 45 μJ. For maximum investigated CW pumping 9.3W the pulse energy was stabilized to 74 μJ which corresponds to the Q-switched pulse peak power 46 kW. The corresponding Q-switched pulses repetition rate was 13.6 kHz. The maximum Yb:YAG/Cr:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over.

  2. Large energy laser pulses with high repetition rate by graphene Q-switched solid-state laser.

    PubMed

    Li, Xian-lei; Xu, Jin-long; Wu, Yong-zhong; He, Jing-liang; Hao, Xiao-peng

    2011-05-01

    We demonstrated that the graphene could be used as an effective saturable absorber for Q-switched solid-state lasers. A graphene saturable absorber mirror was fabricated with large and high-quality graphene sheets deprived from the liquid phase exfoliation. Using this mirror, 105-ns pulses and 2.3-W average output power are obtained from a passively Q-switched Nd:GdVO(4) laser. The maximum pulse energy is 3.2 μJ. The slope efficiency is as high as 37% approximating to 40% of the continue-wave laser, indicating a low intrinsic loss of the graphene. PMID:21643251

  3. Low-threshold and multi-wavelength Q-switched random erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Wang, Simin; Lin, Wei; Chen, Weicheng; Li, Can; Yang, Changsheng; Qiao, Tian; Yang, Zhongmin

    2016-03-01

    We demonstrate a low-threshold and multi-wavelength Q-switched random fiber laser with erbium-doped fiber as the gain medium and Rayleigh scattering as the randomly distributed feedback. Q-switched pulses are generated with threshold as low as 27 mW by combining random cavity resonances and the Q-value modulation effect induced by stimulated Brillouin scattering. The repetition rate is typically on the kilohertz scale with rms timing jitter of <5.5% and rms amplitude fluctuation of <30%. Raman Stokes emissions up to the third order are observed with an overall energy of nearly 42% of the pulse output, which may open an avenue for applications requiring multiple wavelengths.

  4. Multiple folded resonator for LD pulse end pumped Q-switched Yb:YAG slab laser.

    PubMed

    Jun, Liu; Jianguo, Xin; Ye, Lang; Jiabin, Chen

    2014-09-01

    In this paper, a multiple folded resonator is presented which consists of a multiple optical folding setup, a flat total reflector, a flat output coupler, a Q-switch crystal and a polarizer. By this technique, the output energy of 32.6mJ and pulse width of 13.4ns with a repetition rate of 5Hz was obtained, which is three times higher than that reported in the past publications by the use of the currently existing technique of the Q-switched slab gain lasers with the unstable resonator. The output beam with a quality of M² = 1.55 in the slow axis and M² = 1.40 in the fast axis was also obtained. PMID:25321590

  5. Q-switched Erbium-doped fiber laser using MoSe2 as saturable absorber

    NASA Astrophysics Data System (ADS)

    Ahmad, H.; Suthaskumar, M.; Tiu, Z. C.; Zarei, A.; Harun, S. W.

    2016-05-01

    A Q-switched Erbium-doped fiber laser by using MoSe2 thin film as saturable absorber is experimentally demonstrated. The bulk MoSe2 is processed into few layer MoSe2 based on liquid phase exfoliation technique, and further fabricated into thin film by using polyvinyl alcohol polymer. Q-switching operation is obtained from pump power range of 22.4-102.0 mW. The pulse repetition rate shows an increasing trend from 16.9 kHz to 32.8 kHz, whereas the pulse width exhibits a decreasing trend from 59.1 μs to 30.4 μs. The highest pulse energy of 57.9 nJ is obtained at pump power of 102.0 mW.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  8. VCSEL end-pumped passively Q-switched Nd:YAG laser with adjustable pulse energy.

    PubMed

    Goldberg, Lew; McIntosh, Chris; Cole, Brian

    2011-02-28

    A compact, passively Q-switched Nd:YAG laser utilizing a Cr4+:YAG saturable absorber, is end-pumped by the focused emission from an 804 nm vertical-cavity surface-emitting laser (VCSEL) array. By changing the VCSEL operating current, we demonstrated 2x adjustability in the laser output pulse energy, from 9 mJ to 18 mJ. This energy variation was attributed to changes in the angular distribution of VCSEL emission with drive current, resulting in a change in the pump intensity distribution generated by a pump-light-focusing lens. PMID:21369256

  9. Q-switching of a thulium-doped fibre laser using a holmium-doped fibre saturable absorber

    SciTech Connect

    Sadovnikova, Ya E; Kamynin, V A; Kurkov, A S; Medvedkov, O I; Marakulin, A V; Minashina, L A

    2014-01-31

    We have proposed and demonstrated a new passively Q-switched thulium-doped fibre laser configuration. A distinctive feature of this configuration is the use of a heavily holmium-doped fibre for Q-switching. Lasing was obtained at 1.96 μm, with a pulse energy of 3 μJ and pulse duration of 600 ns. The highest pulse repetition rate was 80 kHz. (control of laser radiation parameters)

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

    PubMed

    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 < 1.05). By frequency doubling of the fundamental 1342 nm 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. PMID:26698762

  11. Modulation frequency characteristics of the Q-switched envelope in a doubly Q-switched and mode-locked laser with acousto-optic modulator and Cr4+:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    Qiao, Junpeng; Zhao, Jia; Li, Yufei; Zhao, Shengzhi; Li, Guiqiu; Li, Dechun; Qiao, Wenchao; Chu, Hongwei

    2015-11-01

    The modulation frequency characteristics of the Q-switched envelope in a doubly Q-switched and mode-locked Nd:GGG laser with an acousto-optic modulator (AOM) and Cr4+:YAG saturable absorber are given. At a fixed incident pump power, the repetition rates of the Q-switched envelope and the related laser characteristics versus the modulation frequency of AOM for different small signal transmissions of Cr4+:YAG saturable absorbers have been measured. The experimental results show that the repetition rates of the Q-switched envelope, the average output power, the average peak power, and the pulse widths of the Q-switched envelopes are subharmonics of the modulation frequency at a fixed incident pump power. Furthermore, the mechanism for these behaviors is discussed.

  12. High resolution laser micro sintering / melting using q-switched and high brilliant laser radiation

    NASA Astrophysics Data System (ADS)

    Exner, H.; Streek, A.

    2015-03-01

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

  13. Passively Q-switched diode-pumped Yb:YAG laser using Cr 4+-doped garnets

    NASA Astrophysics Data System (ADS)

    Kalisky, Y.; Labbe, C.; Waichman, K.; Kravchik, L.; Rachum, U.; Deng, P.; Xu, J.; Dong, J.; Chen, W.

    2002-06-01

    We investigate the repetitive modulation in the kHz frequency domain of a passively Q-switched, diode-pumped Yb:YAG laser, by Cr 4+:YAG, Cr 4+:LuAG, and Cr 4+:GSGG saturable absorbers. The results presented here are focused towards the design of a passively Q-switched Yb:YAG microlaser. The free-running performance of both rod and a disk Yb:YAG is characterized and experimental parameters such as gain and loss are evaluated. These values, together with the value of the stimulated emission cross-section, e.g. σem=3.3×10 -20 cm 2 were found to fit between our experimental results and an existing numerical model which relates the experimental and physical parameters to the minimal threshold pumping power. Q-switched pulses with maximum peak power of ≈10.4 kW, with energy of ≈0.5 mJ/pulse, were extracted with 30% extraction efficiency.

  14. Passively Q-switched diode-pumped Yb:YAG laser using Cr4+-doped garnets

    NASA Astrophysics Data System (ADS)

    Kalisky, Yehoshua Y.; Labbe, Christophe; Waichman, Karol; Kravchik, Leonid; Rachum, U.; Deng, Peizhen; Xu, Jun; Dong, Jun; Chen, Wei

    2002-03-01

    We investigated the operation of a diode-pumped Yb:YAG laser passively Q-switched, by Cr4+:YAG, Cr4+:LuAG, and Cr4+:GSGG saturable absorbers. The results presented here are focused towards the design of a passively Q-switched Yb:YAG microlaser. The free-running performance of both rod and a disk Yb:YAG is characterized, and experimental parameters such as gain and loss are evaluated. These values, together with the value of the stimulated emission cross section, e.g. (sigma) emequals3.3x10-20 cm2 were found to fit between our experimental results and an existing numerical model which relates the experimental and physical parameters to the minimal threshold pumping power. Q-switched pulses with maximum peak power of approximately equals 10.4-kW, and energy of approximately equals 0.5 mJ/pulse were extracted with 30% extraction efficiency.

  15. Segment side-pumped Q-switched Nd:YAG laser.

    PubMed

    Wang, Wei; Fu, Chen; Hu, Zhenyue; Zhao, Qin; Gong, Mali

    2012-04-10

    In the design of conduction-cooled lasers, a side-pumped configuration is an attempt to solve the space conflict between pump and heat removal. The pump radiation always competes with the heat removal and mechanical support device for the lateral surface of a laser rod. This space conflict can be addressed by a segment side-pumped configuration in which circular laser diode arrays and heat-conducting rod holders alternate periodically along the length of the laser rod. This scheme permitted 11 Hz operation of a 190 mJ Q-switched laser at the wavelength of 1064 nm without the use of liquid cooling for both the laser rod and laser diode arrays and the corresponding optical-optical conversion efficiency of 23.1%. Thus, it has great potential to be used in compact and miniature laser systems. PMID:22505168

  16. Nonlinear dynamics of Ytterbium-doped fiber laser Q-switched using acousto-optical modulator

    NASA Astrophysics Data System (ADS)

    Barmenkov, Y. O.; Kir'yanov, A. V.; Andres, M. V.

    2014-12-01

    A comprehensive experimental analysis of the dynamics of an ytterbium-doped fiber laser actively Q-switched (QS) using an intracavity acousto-optical modulator (AOM) is presented. It is shown that type of QS pulsing strongly depends on AOM repetition rate and pump power. In particular, at low repetition rates, including zero-rate, and at relatively high pump powers peculiar QS pulsing, switched by stimulated Brillouin scattering (SBS), is established in the laser. The cause of such kind of pulsing is the SBS-process boosted by spurious narrow-line CW lasing that arises in auxiliary low-Q cavity formed by an output coupler (in our experiments - fiber Bragg gratings) and weak reflections from blocked AOM. The parameters' area where this regime occurs is limited by certain values of pump power and AOM repetition rate. At increasing AOM repetition rate or decreasing pump power spurious CW lasing is not attained in the system; consequently, the SBS type of QS fades, while "conventional" QS (CQS) lasing is established in the system and remains. However CQS pulsing strongly suffers the nonlinear-dynamics effects: depending on AOM repetition rate and pump power the laser switches to common P1, P2, or P3 attractors, when QS pulses arise at sub-harmonics of AOM repetition rate, or to the specific transient regimes between them, or to chaotic operation. These and other sides (e.g. pulse jittering) of operation of the QS ytterbium-doped fiber laser with AOM are under scope of the present review as they have big interest for practical applications.

  17. Detonation of insensitive high explosives by a Q-switched ruby laser.

    NASA Technical Reports Server (NTRS)

    Yang, L. C.; Menichelli, V. J.

    1971-01-01

    Immediate longitudinal detonations have been observed in confined small-diameter columns of PETN, RDX, and tetryl by using a focused Q-switched ruby laser. The energy ranged from 0.8 to 4.0 J in a pulse width of 25 nsec. A 1000-A-thick aluminum film deposited on a glass window was used to generate a shock wave at the window-explosive interface when irradiated by the laser. In some cases, steady-state detonations were reached in less than .5 microsec with less than 10% variation in the detonation velocity.

  18. Passively Q-switched Ho:YLF laser pumped by Tm3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Ju, Youlun; Yao, Baoquan; Dai, Tongyu; Duan, Xiaoming; Li, Jiang; Ding, Yu; Liu, Wei; Pan, Yubai; Li, Chaoyu

    2016-03-01

    We demonstrate a compact and efficient passively Q-switched (PQS) Ho:YLF laser pumped by a self-made all-fiber laser. Firstly, we design and make an all-fiber laser operating at 1940 nm with a slope efficiency of 40.6%. Then, the all-fiber laser was used to pump Ho:YLF laser directly. In the CW (continues-wave) operation Ho:YLF laser, the maximum output power was 7.79 W, corresponding to the slope efficiency of 55.2%. Using Cr2+:ZnS as the saturable absorber, the average power of 6.03 W was achieved with the slope efficiency of 45.9%. The shortest pulse duration was 15.6 ns and the pulse repetition frequency was 2.3 kHz at the pump power of 20.4 W. The pulse energy was a constant as 2.7 mJ when the pump power exceeded 15 W. The beam quality factor of M2 was 1.05, indicating nearly diffraction limited beam propagation.

  19. 520 mJ langasite electro-optically Q-switched Cr, Tm, Ho:YAG laser.

    PubMed

    Wang, Li; Cai, Xuwu; Yang, Jingwei; Wu, Xianyou; Jiang, Haihe; Wang, Jiyang

    2012-06-01

    A flash lamp pumped 2.09 μm Cr, Tm, Ho:YAG laser utilizing a self-grown La(3)Ga(5)SiO(14) crystal as the electro-optic Q-switch generator is proposed and demonstrated for the first time. Operating at 3 Hz repetition rate, 520 mJ pulse energy with 35 ns pulse width is achieved by optimizing the Q-switch delay time and compensating for the thermal depolarization with a quarter-wave plate. The corresponding peak power is 14.86 MW, and the Q-switched-to-normal-mode energy extraction efficiency is 66.3%. To our knowledge, this Q-switched giant pulse is the best result reported to date in 2.09 μm laser resonator. PMID:22660096

  20. Single-frequency Q-switched erbium-doped fiber ring laser by combination of a distributed Bragg reflector laser and a Mach-Zender interferometer.

    PubMed

    Wang, Anting; Ming, Hai; Xie, Jianping; Chen, Xiyao; Lv, Liang; Huang, Wencai; Xu, Lixin

    2003-06-20

    A single-frequency Q-switched erbium-doped fiber ring laser is implemented for producing a single frequency with 25-Mhz laser linewidth, Q-switched pulses with a high peak power at 1557.5 mm. The single longitudinal mode is selected by a distributed Bragg reflector fiber laser, and a fiberoptic Mach-Zehnder interferometer acts as a Q-switch. The peak power and the average power of the Q-switched pulses vary with the repetition rate. PMID:12833955

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  2. Narrow-linewidth Q-switched random distributed feedback fiber laser.

    PubMed

    Xu, Jiangming; Ye, Jun; Xiao, Hu; Leng, Jinyong; Wu, Jian; Zhang, Hanwei; Zhou, Pu

    2016-08-22

    A narrow-linewidth Q-switched random fiber laser (RFL) based on a half-opened cavity, which is realized by narrow-linewidth fiber Bragg grating (FBG) and a section of 3 km passive fiber, has been proposed and experimentally investigated. The narrow-linewidth lasing is generated by the spectral filtering of three FBGs with linewidth of 1.21 nm, 0.56 nm, and 0.12 nm, respectively. The Q switching of the distributed cavity is achieved by placing an acousto-optical modulator (AOM) between the FBG and the passive fiber. The maximal output powers of the narrow-linewidth RFLs with the three different FBGs are 0.54 W, 0.27 W, and 0.08 W, respectively. Furthermore, the repetition rates of the output pulses are 500 kHz, and the pulse durations are about 500 ns. The corresponding pulse energies are about 1.08 μJ, 0.54 μJ, and 0.16 μJ, accordingly. The linewidth of FBG can influence the output characteristics in full scale. The narrower the FBG, the higher the pump threshold; the lower the output power at the same pump level, the more serious the linewidth broadening; and thus the higher the proportion of the CW-ground exists in the output pulse trains. Thanks to the assistance of the band-pass filter (BPF), the proportion of the CW-ground of narrow-linewidth Q-switched RFL under the relative high-pump-low-output condition can be reduced effectively. The experimental results indicate that it is challenging to demonstrate a narrow-linewidth Q-switched RFL with high quality output. But further power scaling and linewidth narrowing is possible in the case of operating parameters, optimization efforts, and a more powerful pump source. To the best of our knowledge, this is the first demonstration of narrow-linewidth generation in a Q-switched RFL. PMID:27557200

  3. Correct calibration procedure for the Q-switched ruby laser and checking the treatment irradiation pattern

    PubMed Central

    Ohshiro, Takafumi; Sasaki, Katsumi; Takenouchi, Kiyofumi; Kozuma, Mituaki; Ohshiro, Naoyuki; Kageyama, Yuichi

    2013-01-01

    Background and aims: There are many Q-switched lasers. The Q-switched ruby laser is the one most popularly used in dermatology, aesthetic surgery and plastic surgery, to remove pigmented lesions or tattoos. Correct and regular calibration of such a system is essential. However, some clinics fail to perform this with the excuse of having no measuring instrument (MI) in their offices or treatment rooms in some of their hospitals or clinics, or even the case of well-known medical universities in Japan. The present article explains the precise calibration procedure and beam pattern checking for the Q-switched ruby systems in the first author's clinic. Rationale: In the case of treatment with a medical laser, the calibration and the irradiated pattern (IP) check of the laser being used for treatment are the most important factors for treatment efficacy and safety. If these factors change, the treatment result could be different from that expected. Such kind of data are not acceptable as scientific information for a presentation or published paper. With such unreliable results and incorrect beam pattern, replicating such a study would be impossible Regular calibration check: In our clinic, we have 2 Q-switched ruby laser systems. On a daily basis, the beam patterns, both the optical axis of the beam and its treatment footprint, are checked on dedicated printed sheets and footprint paper, respectively, at the beginning of the day and after the last procedure. Every two weeks we calibrate our systems in-house using a precise MI. Every six months we calibrate the systems in-house with the MI, and then we send the systems back to the manufacturers for calibration. Once every year, we have our MI calibrated by an accredited facility in Japan. In this way, we are not only ensuring accurate and safe treatment for our patients, but we are also producing accurate system and treatment data which can be replicated by others, the basis of evidence-based medicine. PMID:24204090

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  5. Characterization of the Q-switched MOBLAS Laser Transmitter and Its Ranging Performance Relative to a PTM Q-switched System

    NASA Technical Reports Server (NTRS)

    Degnan, J. J., III; Zagwodski, T. W.

    1979-01-01

    A prototype Q-switched Nd:YAG laser transmitter intended for use in the NASA mobile laser ranging system was subjected to various tests of temporal pulse shape and stability, output energy and stability, beam divergence, and range bias errors. Peak to peak variations in the mean range were as large as 30 cm and drift rates of system bias with time as large as 6 mm per minute of operation were observed. The incorporation of a fast electro-optic cavity dump into the oscillator gave significantly improved results. Reevaluation of the ranging performance after modification showed a reduction in the peak to peak variation in the mean range to the 2 or 3 cm level and a drift rate of system time biases of less than 1 mm per minute of operation. A qualitative physical explanation for the superior performance of cavity dumped lasers is given.

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

    SciTech Connect

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

    1989-01-01

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

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

    SciTech Connect

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

    1987-09-01

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

  8. Acousto-optic Q-switching laser performance of Yb:GdCa(4)O(BO(3))(3)crystal.

    PubMed

    Chen, Xiaowen; Xu, Honghao; Guo, Yunfeng; Han, Wenjuan; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-08-20

    We report on the active Q-switching laser performance of Yb:GdCa4O(BO3)3 crystal, demonstrated by employing an acousto-optic Q-switch in a compact plano-concave resonator. Stable repetitively Q-switched operation is achieved with pulse repetition rates varying from 30 to 0.2 kHz, producing an average output power of 10.2 W at 1027.5 nm at 30 kHz of repetition rate, with an optical-to-optical efficiency of 30%. The maximum pulse energy generated at the lowest repetition rate of 0.2 kHz is 4.75 mJ, with a pulse width being 11 ns, gives rise to a peak power that amounts to 432 kW. PMID:26368745

  9. The passive Q-switching regime in a solid state laser with a multiloop cavity

    NASA Astrophysics Data System (ADS)

    Pogoda, A. P.; Burkovskii, G. V.; Makarchuk, P. S.; Khakhalin, I. S.; Boreisho, A. S.; Fedin, A. V.

    2016-03-01

    A compact, pulsed-periodic YAG: Nd3+ laser with self-pumped phase-conjugate multiloop cavity and passive Q-switching by YAG: Cr 4+ and GSGG: Cr 4+ crystals has been studied. It is established that the energy and temporal parameters of radiation in separate pulses of a periodic train can be controlled almost without changing the pulse train energy. A regime of generating modulated radiation pulses with a peak power of up to 30 MW and a spatial brightness of 1.7 × 1015 W/(cm2 sr) at a radiation beam quality parameter of M 2 < 1.2 has been realized in experiment.

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

    NASA Astrophysics Data System (ADS)

    Wang, Yong Gang; Chen, Hou Ren; Wen, Xiao Ming; Hsieh, Wen Feng; Tang, Jau

    2011-11-01

    We demonstrated that graphene oxide material could be used as a highly efficient saturable absorber for the Q-switched Nd:GdVO4 laser. A novel and low-cost graphene oxide (GO) absorber was fabricated by a vertical evaporation technique and high viscosity of polyvinyl alcohol (PVA) aqueous solution. A piece of GO/PVA absorber, a piece of round quartz, and an output coupler mirror were combined to be a sandwich structure passive component. Using such a structure, 104 ns pulses and 1.22 W average output power were obtained with the maximum pulse energy at 2 µJ and a slope efficiency of 17%.

  11. Processing of Ni-based aero engine components with repetitively Q-switched Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Bostanjoglo, Georg; Sarady, Istvan; Beck, Thomas; Weber, Horst

    1996-09-01

    Aircraft engine industry uses free running high power Nd:YAG lasers for drilling cooling holes into nickel base alloy turbine components. A cw-pumped, Q-switched, high beam quality laser system with 400W laser power is presented. The laser is used to trepan drilling of 1.6mm. Hastelloy X sheets and ceramic coated combustion chamber tubes of the same metal. Cylindrical shape, uniformity, and reproducibility are achieved with a trepan-like drilling setup. The heat load of the workpiece as well as the process time is considerably decreased by employing high-repetition Q-switched lasers.

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

    NASA Astrophysics Data System (ADS)

    Xu, Shan; Gao, Shufang; Zheng, Chunyan

    2016-06-01

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

  13. Radially polarized and pulsed output from passively Q-switched Nd:YAG ceramic microchip laser.

    PubMed

    Li, Jian-lang; Ueda, Ken-ichi; Musha, Mitsuru; Zhong, Lan-xiang; Shirakawa, Akira

    2008-11-15

    For the first time, to the best of our knowledge, a radially polarized laser pulse was produced from a passively Q-switched Nd:YAG ceramic microchip laser with a piece of Cr4+:YAG crystal as the saturable absorber and multilayer concentric subwavelength grating as the polarization-selective output coupler. The averaged laser power reached 450 mW with a slope efficiency of 30.2%. The laser pulse had a maximum peak power of 759 W, a minimum pulse duration of 86 ns, and a 6.7 kHz repetition rate at 3.7 W absorbed pump power. The polarization degree of the radially polarized pulse was measured to be as high as 97.4%. Such a radially polarized laser pulse with a high peak power and a short width is important to numerous applications such as metal cutting. PMID:19015709

  14. Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury.

    PubMed

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

    2005-03-20

    A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury. PMID:15813276

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Continuous-wave and passively Q-switched Nd:LYSO lasers

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    Continuous-wave (CW) and passively Q-switched performance of a Nd-doped oyorthosilicate mixing crystal, (Nd0.005Lu0.4975Y0.4975)2SiO5 (Nd:LYSO), were reported. As a result, new dual-wavelength all-solid-state lasers at 1075 and 1079 nm were achieved. When the absorbed pump power was 3.87 W, the CW laser produced 1.1 W output, corresponding to an optical conversion efficiency of 28.4% and a slope efficiency of 32.4%. By using a Cr4+:YAG wafer as the saturable absorber, we achieved Q-switching operation of Nd:LYSO crystal. The maximal average output power, shortest pulse width, largest pulse energy and highest peak power were measured to be 294 mW, 27.5 ns, 34.3 μJ and 1.18 kW, respectively. By difference frequency, these dual-wavelength lasers have potential applications for the generation of a broadband coherent radiation from 0.7-1.3 THz.

  17. Comparison of high repetition rate Q-switched 355nm ultraviolet lasers with EOM and AOM

    NASA Astrophysics Data System (ADS)

    Lu, Tingting; Li, Xiaolei; Zang, Huaguo; Zhu, Xiaolei

    2013-05-01

    Two kinds of Q-switched ultraviolet lasers using an acousto-optic modulator and an electro-optic modulator in the same cavity structure are demonstrated, with type I phase-matched LBO as second harmonic generation crystal and type II phase-matched LBO as third harmonic generation crystal. For acousto-optic Q-switched UV laser-a maximum average power of 6.3W with the shortest pulse width of 12 ns was obtained at the repetition rate of 22 kHz when the pump power reached 52.4 W. The optical conversion efficiency was up to 12%. Then we used a La3Ga5SiO14 crystal electro-optic modulator to replace the acousto-optic modulator. The 1.29W output power at 355nm wavelength was obtained at the repetition rate of 10 kHz when the pump power was increased to 20.4W, and the UV laser pulse width was as short as 9.6ns.The optical conversion efficiency was up to 6.3%.

  18. Highly efficient passively Q-switched Tm,Ho:GdVO4 laser with kilowatt peak power

    NASA Astrophysics Data System (ADS)

    Du, Yanqiu; Yao, Baoquan; Liu, Wei; Cui, Zheng; Duan, Xiaoming; Ju, Youlun; Yu, Hong

    2016-04-01

    We present the experimental results on the laser characteristics of diode-pumped passively Q-switched Tm,Ho:GdVO4 and Tm,Ho:YVO4 lasers with a Cr2+:ZnS saturable absorber emitting in the 2-μm range. The Tm,Ho:GdVO4 laser exhibits better performance than the Tm,Ho:YVO4 laser. The minimum pulse duration of 32.7 ns is obtained with the pulse energy of 0.30 mJ, corresponding to the peak power of 9.1 kW. The slope efficiencies of continuous wave and passively Q-switched Tm,Ho:GdVO4 lasers are 49.9% and 36.5%, corresponding to the Q-switching efficiency of 70.2%.

  19. Q-switched all-solid-state lasers and application in processing of thin-film solar cell

    NASA Astrophysics Data System (ADS)

    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.

  20. Highly efficient passively Q-switched Yb:YAG microchip lasers under high intensity laser-diode pumping

    NASA Astrophysics Data System (ADS)

    Dong, J.; Wang, G. Y.; Cheng, Y.

    2013-03-01

    A highly efficient Cr4+:YAG passively Q-switched Yb:YAG microchip laser has been demonstrated at room temperature by high-brightness single-emitter laser-diode pumping. The maximum average output power of 1.53 W was obtained at the absorbed pump power of 3.5 W. The optical-to-optical efficiency was 44% with respect to the absorbed pump power. Laser pulses with a pulse width of 2.9 ns, pulse energy of 11.3 μJ, and peak power of 3.9 kW were obtained. The high pump power intensity from a high-brightness single-emitter laser-diode plays an important role in the alleviation of thermal effects and the efficient performance of Cr4+:YAG passively Q-switched Yb:YAG microchip lasers.

  1. Variable energy, high peak power, passive Q-switching diode end-pumped Yb:LuAG laser

    NASA Astrophysics Data System (ADS)

    Kaskow, M.; Sulc, J.; Jabczynski, J. K.; Jelinkova, H.

    2014-12-01

    A new method to control the pulse energy in a passively Q-switched laser was proposed and experimentally verified for a diode-end-pumped Yb:LuAG laser. By changing the pumping area parameters it was possible to demonstrate generation of a wide range of output energies with a single laser configuration consisting of a gain medium, passive Q-switch and out-coupling mirror. The range of available energies 0.15-0.51 mJ with maximum peak power of 113 kW in simple Q-switching regime by means of a Cr:YAG saturable absorber and a Yb:LuAG gain medium pumped by a 20 W laser diode emitting at 968 nm was demonstrated.

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

    NASA Astrophysics Data System (ADS)

    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. Passively Q-switched Nd:YAG ceramic microchip laser with azimuthally polarized output

    NASA Astrophysics Data System (ADS)

    Li, J.-L.; Lin, D.; Zhong, L.-X.; Ueda, K.; Shirakawa, A.; Musha, M.; Chen, W.-B.

    2009-10-01

    A passively-Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) ceramic microchip laser was demonstrated to emit azimuthally polarized beam bus using a chromium-doped YAG (Cr4+:YAG) crystal as saturable absorber and a multilayer concentric subwavelength grating as polarization-selective output coupler. The laser's output power reached 512 mW with an initial slope efficiency of nearly 60%, and the pulse had 1.15-kW peak power with 40-ns duration and 11-kHz repetition rate at 3.9-W absorbed pump power. The laser beam's polarization degree was 97.6%. The thermal lensing effect in Nd:YAG microchip remained as a problem to be solved.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Passive Q-switching of an all-fiber laser induced by the Kerr effect of multimode interference.

    PubMed

    Fu, Shijie; Sheng, Quan; Zhu, Xiushan; Shi, Wei; Yao, Jianquan; Shi, Guannan; Norwood, R A; Peyghambarian, N

    2015-06-29

    A novel passively Q-switched all-fiber laser using a single mode-multimode-single mode fiber device as the saturable absorber based on the Kerr effect of multimode interference is reported. Stable Q-switched operation of an Er(3+)/Yb(3+) co-doped fiber laser at 1559.5 nm was obtained at a pump power range of 190-510 mW with the repetition rate varying from 14.1 kHz to 35.2 kHz and the pulse duration ranging from 5.69 μs to 3.86 μs. A maximum pulse energy of 0.8 μJ at an average output power of 27.6 mW was achieved. This demonstrates a new modulation mechanism for realizing Q-switched all-fiber laser sources. PMID:26191734

  6. On the Q-switched operation of Titanium:Sapphire lasers using a graphene-based saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Weigand, R.; Pinto, T.; Crespo, H. M.; Guerra, J. M.

    2015-09-01

    We numerically demonstrate Q-switched operation of Titanium:Sapphire lasers using mono and multilayer graphene, deposited on a totally reflecting end mirror as a saturable absorber. Output energies, pulse duration and repetition frequencies of the Q-switched pulse trains are given as a function of the pump intensity for different number of graphene layers and cavity lengths. For the geometries studied, pulses from 17 to 491 ns can be achieved, with energies ranging from 11 to 74 μJ and repetition rates from 0.06 to 2.5 MHz. These results can be useful for designing and building laser cavities for Q-switched and mode-locked operation in laser media with short lifetimes as Titanium:Sapphire.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Q-switched operation of a femtosecond-laser-inscribed Yb:YAG channel waveguide laser using carbon nanotubes.

    PubMed

    Choi, Sun Young; Calmano, Thomas; Kim, Mi Hye; Yeom, Dong-Il; Kränkel, Christian; Huber, Günter; Rotermund, Fabian

    2015-03-23

    We demonstrate a diode-pumped femtosecond-laser-inscribed Yb:YAG channel waveguide laser, Q-switched by using single-walled carbon nanotubes (SWCNTs) near 1029 nm. We used saturable absorber mirrors (SAMs) fabricated by depositing SWCNTs on three different output couplers. Best performance of the 9.3-mm-long ultra-compact Q-switched waveguide laser is obtained with an output coupling transmission of 20%. In this case, a maximum average output power of 60 mW with a corresponding pulse energy of 37.7 nJ and a pulse duration of 88 ns at 1.59-MHz repetition rate were achieved. The highest pulse energy of 39.2 nJ and the shortest pulse duration of 78 ns were obtained with 30% and 10% output couplers, respectively. PMID:25837137

  9. Q-switching of a high-power solid-state laser by a fast scanning Fabry-Perot interferometer

    SciTech Connect

    Baburin, N V; Borozdov, Yu V; Danileiko, Yu K; Denker, B I; Ivanov, A D; Osiko, Vyacheslav V; Sverchkov, S E; Sidorin, A V; Chikov, V A; Ifflander, R; Hack, R; Kertesz, I; Kroo, N

    1998-07-31

    An investigation was made of the suitability of a Q-switch, based on a piezoelectrically scanned short-base Fabry-Perot interferometer, for an Nd{sup 3+}:YAG laser with an average output radiation power up to 2 kW. The proposed switch made it possible to generate of giant pulses of 60 - 300 ns duration at a repetition rate of 20 - 100 kHz. Throughout the investigated range of the pulse repetition rates the average power was at least equal to that obtained by cw lasing. Special requirements to be satisfied by the interferometer, essential for efficient Q-switching, were considered. (control of laser radiation parameters)

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

    SciTech Connect

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

    2012-02-28

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

  11. 1.4-MHz repetition rate electro-optic Q-switched Nd:YVO4 laser.

    PubMed

    Horiuchi, Ryusuke; Adachi, Koji; Watanabe, Goro; Tei, Kazuyoku; Yamaguchi, Shigeru

    2008-10-13

    An electro-optic (EO) deflector was used for Q-switching of a laser cavity with a Nd-doped yttrium vanadate (Nd:YVO(4)), enabling a short pulse width and a high peak power to be achieved at a high repetition rate of over 1 MHz. The EO deflector has a low optical loss during Q-switching without polarizers and can be used to form a short laser cavity. A repetition rate of 1.4 MHz with a pulse width of 39 ns was achieved. An output power of 2.7 W was obtained at a pump power of 6.5 W. PMID:18852782

  12. All-optical Q-switching limiter for high-power gigahertz modelocked diode-pumped solid-state lasers.

    PubMed

    Klenner, Alexander; Keller, Ursula

    2015-04-01

    Passively modelocked diode-pumped solid-state lasers (DPSSLs) with pulse repetition rates in the gigahertz regime suffer from an increased tendency for Q-switching instabilities. Low saturation fluence intracavity saturable absorbers - such as the semiconductor saturable absorber mirrors (SESAMs) - can solve this problem up to a certain average output power limited by the onset of SESAM damage. Here we present a passive stabilization mechanism, an all-optical Q-switching limiter, to reduce the impact of Q-switching instabilities and increase the potential output power of SESAM modelocked lasers in the gigahertz regime. With a proper cavity design a Kerr lens induced negative saturable absorber clamps the maximum fluence on the SESAM and therefore limits the onset of Q-switching instabilities. No critical cavity alignment is required because this Q-switching limiter acts well within the cavity stability regime. Using a proper cavity design, a high-power diode-pumped Yb:CALGO solid-state laser generated sub-100 fs pulses with an average output power of 4.1 W at a pulse repetition rate of 5 GHz. With a pulse duration of 96 fs we can achieve a peak power as high as 7.5 kW directly from the SESAM modelocked laser oscillator without any further external pulse amplification and/or pulse compression. We present a quantitative analysis of this Kerr lens induced Q-switching limiter and its impact on modelocked operation. Our work provides a route to compact high-power multi-gigahertz frequency combs based on SESAM modelocked diode-pumped solid-state lasers without any additional external amplification or pulse compression. PMID:25968691

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  14. Comprehensive study of electro-optic and passive Q-switching in solid state lasers for altimeter applications

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  15. Design and construction of Q-switched Nd:YAG laser system for LIBS measurements

    NASA Astrophysics Data System (ADS)

    Elsayed, Khaled.; Imam, Hisham; Harfoosh, Amro; Hassebo, Yasser; Elbaz, Yasser; Aziz, Mouayed; Mansour, Mohy

    2012-02-01

    A passive, Q-switched pulsed, Nd:YAG laser system was designed and built, which can provide a potential compact robust laser source for portable laser induced breakdown spectroscopy systems. The developed laser system operates at 1064 nm. Each laser shot contains a train of pulses having maximum total output energy of 170 mJ. The number of pulses varies from 1-6 pulses in each laser shot depending on the pump energy. The pulse width of each pulse ranges from 20 to 30 ns. The total duration of the output pulse train is within 300 μs. The multi-pulse nature of the laser shots was employed to enhance the LIBS signal. To validate the system, LIBS measurements and analysis were performed on ancient ceramic samples collected from Al-Fustat excavation in Old Cairo. The samples belong to different Islamic periods in Egypt history. The results obtained are highly indicative that useful information can be provided to archeologists for use in restoring and repairing of precious archeological objects.

  16. Treatment of traumatic tattoo with the Q-switched Nd:YAG laser.

    PubMed

    Gorouhi, Farzam; Davari, Parastoo; Kashani, Mansour Nassiri; Firooz, Alireza

    2007-12-01

    Traumatic tattoos are undesirable tattoos caused by different foreign bodies such as fireworks' particles, sand, metals, glass, gunpowder, asphalt, dust, or petroleum products embedded forcefully in the dermis. We report the case of a 54-year-old man who presented with sand and asphalt tattooing on his face following a bomb explosion 15 years ago. Q-switched Nd:YAG laser at a wavelength of 1064 nm with a spot size of 4 mm and a fluence of 7.96 J/cm(2) were applied to treat the patient. The patient tolerated the treatment very well. Most of the blue dots became whitened immediately after the procedure and remained almost clear after a 6-month follow-up. PMID:18236246

  17. Synchronous initiation of optical detonators by Q-switched solid laser sources

    NASA Astrophysics Data System (ADS)

    Goujon, J.; Musset, O.; Marchand, A.; Bigot, C.

    2008-10-01

    The initiation of pyrotechnic substances by a laser light has been studied for more than 30 years. But until recently the use of this technology for defence applications encountered three main technical problems: the volume and the mass of lasers, the linear loss of optical fibres and their possible damage caused by the transport of strong laser power. Recent technical progress performed in the field of electrical and optical devices are now very promising for future opto-pyrotechnic functional chains. The objective of this paper is to present a demonstrator developed in order to initiate in a synchronous way four optical detonators and to measure the dispersion of their functioning times. It includes four compact Q-switched Nd:Cr:GSGG solid laser sources, pumped by flash lamp (energy ~110mJ, FWHM ~8.5 ns), two ultra-fast electro-optical selectors (based on RTP crystals) used to steer the laser beam and six optical fibre lines to transmit the laser pulses to the optical detonators. The set-up integrates also complex control and safety systems, as well as cameras allowing an optimal alignment of optical fibres. Experiments led us to initiate in a synchronous way four detonators with a mean scattering of 50 ns. The perspectives in this domain of initiation concern mainly the miniaturization and the hardening to the environments of electrical and optical components.

  18. Influence of UV illumination on the cold temperature operation of a LiNbO(3) Q-switched Nd:YAG laser.

    PubMed

    Cole, Brian; Goldberg, Lew; King, Vernon; Leach, Jeff

    2010-04-26

    UV illumination of a lithium niobate Q-switch was demonstrated as an effective means to eliminate a loss in hold-off and associated prelasing that occurs under cold temperature operation of Q-switched lasers. This degradation occurs due to the pyroelectric effect, where an accumulation of charge on crystal faces results in a reduction in the Q-switch hold-off and a spatially variable loss of the Q-switch in its high-transmission state, both resulting in lowering of the maximum Q-switched pulse energy. With UV illumination, the resulting creation of photo-generated carriers was shown to be effective in eliminating both of these effects. A Q-switched Nd:YAG laser utilizing UV-illuminated LiNbO(3) was shown to operate under cold temperatures without prelasing or spatially variable loss. PMID:20588809

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

    PubMed

    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. PMID:26406500

  20. Treatment of early-stage erythematotelangiectatic rosacea with a Q-switched 595-nm Nd:YAG laser.

    PubMed

    Goo, Boncheol Leo; Kang, Jin-Soo; Cho, Sung Bin

    2015-06-01

    Erythematotelangiectatic rosacea presents as persistent erythema and telangiectasia with frequent flushing and blushing on the facial and extrafacial skin. Additionally, papulopustular rosacea shows acneiform papules, pustules, and nodules with persistent plaque-form edema. Despite garnering only grade-C or -D level recommendations, a 585-nm or 595-nm flashlamp-pumped pulsed-dye laser can be considered as an effective therapeutic modality for the treatment of rosacea in patients who are refractory to topical and/or systemic treatments. In this report, treatment with a Q-switched 595-nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with low non-purpuragenic fluence proved to be safe and effective in treating early-stage erythematotelangiectatic rosacea in two female Korean patients. Laser treatment for rosacea was delivered with the settings of pulse energy of 0.4-0.5 J/cm(2), pulse duration of 5-10 ns, 5-mm spot size, 5 Hz, and 500 shots. Additionally, we found that remarkable therapeutic effects were achieved for both rosacea and melasma by combining Q-switched quick pulse-to-pulse 1,064-nm Nd:YAG and Q-switched 595-nm Nd:YAG laser treatments, which required only the changing of handpieces equipped with solid dye. In conclusion, we suggest that treatment with a Q-switched 595-nm Nd:YAG laser with low fluence may provide an additional therapeutic option for treating early-stage erythematotelangiectatic rosacea. PMID:25549817

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

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

    PubMed

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

    2015-12-01

    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. PMID:26662067

  3. Coupled-cavity electro-optically {ital Q}-switched Nd:YVO{sub 4} microchip lasers

    SciTech Connect

    Zayhowski, J.J.; Dill, C. III

    1995-04-01

    Nd:YVO{sub 4} microchip lasers have been electro-optically {ital Q} switched to produce 12-{mu}J pulses of 115-ps duration at repetition rates of up to 1 kHz. At a repetition rate of 2.25 MHz, 0.16-{mu}J pulses with an 8.8-ns duration were obtained.

  4. Continuously-tunable, narrow-linewidth, Q-switched Cr:LiSAF laser for lidar applications

    SciTech Connect

    Early, J.W.; Lester, C.S.; Quick, C.R.; Tiee, J.J.; Shimada, T.; Cockroft, N.J.

    1995-02-01

    A continuously-tunable, narrow-linewidth, flashlamp-pumped, Q-switched Cr:LiSAF laser has been developed (energy: 30 mJ, pulsewidth: 40 ns, linewidth:<2 GHz) and was used successfully for the DIAL(differential absorption lidar) measurements of atmospheric water vapor and LIF lidar for the remote detection of metal oxide fluorescence.

  5. Processing of Diamond for Integrated Optic Devices Using Q-Switched Nd:YAG Laser at Different Wavelengths

    NASA Astrophysics Data System (ADS)

    Sudheer, S. K.; Pillai, V. P. Mahadevan; Nayar, V. U.

    In the present investigation, a Q-switched Nd:YAG laser is used to study the various aspects of diamond processing for fabricating integrated optic and UV optoelectronic devices. Diamond is a better choice of substrate compared to silicon and gallium arsenide for the fabrication of waveguides to perform operations such as modulation, switching, multiplexing, and filtering, particularly in the ultraviolet spectrum. The experimental setup of the present investigation consists of two Q-Switched Nd:YAG lasers capable of operating at wavelengths of 1064 nm and 532 nm. The diamond cutting is performed using these two wavelengths by making the "V"-shaped groove with various opening angle. The variation of material loss of diamond during cutting is noted for the two wavelengths. The cut surface morphology and elemental and structural analysis of graphite formed during processing in both cases are compared using scanning electron microscopy (SEM) and laser Raman spectroscopy. Both the Q-Switched Nd:YAG laser systems (at 1064 nm and 532 nm) show very good performance in terms of peak-to-peak output stability, minimal spot diameter, smaller divergence angle, higher peak power in Q-switched mode, and good fundamental TEM00 mode quality for processing natural diamond stones. Less material loss and minimal micro cracks are achieved with wavelength 532 nm whereas a better diamond cut surface is achieved with processing at 1064 nm with minimum roughness.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  7. Continuously-tunable, narrow-linewidth, Q-switched Cr:LiSAF laser for lidar applications

    SciTech Connect

    Shimada, Tsutomu; Early, J.W.; Lester, C.S.; Quick, C.R.; Tiee, J.J.; Cockroft, N.J.

    1994-10-01

    A continuously-tunable, narrow-linewidth, flashlamp-pumped, Q-switched Cr:LiSAF laser has been developed (energy: 30 mJ, pulsewidth: 40 ns, linewidth: <2 GHz) and was used successfully for the DIAL (differential absorption lidar) measurements of atmospheric water vapor.

  8. Linearly polarized Q-switched ceramic laser made with anisotropic nanostructured thin films.

    PubMed

    Doucet, Alexandre; Beydaghyan, Gisia; Ashrit, Pandurang V; Bisson, Jean-François

    2016-07-01

    A polarizing laser mirror was made of an alternating sequence of low and high refractive index layers of titanium oxide using glancing angle deposition (GLAD). Large refractive index contrast and large birefringence, reaching 0.5 and 0.1, respectively, could be obtained from one single raw material by changing the deposition conditions. The laser mirror could withstand a train of 2.7 ns, single-mode pulses at 680 Hz, λ=1030  nm, and peak power density of 670  MW/cm2 when used as an output coupler of a passively Q-switched (Yb0.1Y0.9)3Al5O12 ceramic laser. The polarization extinction ratio was found to be better than 30 dB both in continuous-wave and pulsed regimes. These results indicate that polarizing laser mirrors made from nanostructured thin films with GLAD, in addition to being simple to fabricate, can withstand high pulse energy density. PMID:27409193

  9. Treatment of persistent Mongolian spots with Q-switched alexandrite laser.

    PubMed

    Kagami, Shinji; Asahina, Akihiko; Uwajima, Yuta; Miyamoto, Akie; Yamada, Daisuke; Shibata, Sayaka; Yamamoto, Mizuho; Masui, Yuri; Sato, Shinichi

    2012-11-01

    Mongolian spots are congenital and confluent hyperpigmented areas that are usually grayish blue in color. They are found most frequently in the sacral region in infants and typically disappear during childhood. Occasionally, they persist to adulthood. We retrospectively examined outcomes of laser treatment of persistent Mongolian spots. We used Q-switched alexandrite laser to treat persistent Mongolian spots of 16 Japanese patients at 14 years old or older. A good therapeutic outcome was achieved overall; however, postinflammatory hyperpigmentation and hypopigmentation were observed in two patients, respectively. While laser treatment was effective for all seven patients with extrasacral Mongolian spots, four out of ten patients with sacral Mongolian spots were refractory to treatment. Of these patients, two received laser irradiation only twice and abandoned treatment, simply because of unsatisfactory results without any adverse events. The other two patients received treatments at intervals of 3 months, which resulted in postinflammatory hyperpigmentation. Contrary to children, who generally show good response after two or three sessions of irradiation, we should consider more frequent irradiation, longer intervals between treatment sessions, and use of bleaching creams in the treatment of persistent sacral Mongolian spots in adults. PMID:22565344

  10. Morphologic evaluations of Q-switched Nd:YAG laser injury of human retina

    NASA Astrophysics Data System (ADS)

    Scales, David K.; Schuschereba, Steven T.; Lund, David J.; Stuck, Bruce E.

    1997-05-01

    Depiction of the cellular and immune responses in the human model is critical to design rational therapies preventing/limiting cellular destruction and ultimately functional visual loss following acute laser injuries. We report the light and electron microscopy histologic findings in a controlled ocular human laser exposure. Following informed consent, the normal eye of a patient scheduled to undergo exenteration for invasive carcinoma of the orbit was exposed to both continuous wave and Q-switched lasers. Four hours prior to exenteration, argon G lesions were placed in the superior/temporal quadrant and Nd:YAG lesions were placed in the inferior/temporal quadrant. After enucleation, the retina was prepared for routine light and transmission electron microscopy. Histology of the argon G lesions showed primarily photoreceptor and RPE photocoagulation damage. Neutrophil adhesion was limited within the choroid and no neutrophils were observed in the subretinal space. In contrast, the 4 hr Nd:YAG lesions showed extensive retinal disruption, hemorrhage within subretinal and intraretinal spaces, neutrophil accumulation in the retina, and an extensive neutrophil chemotaxic and emigration response in the choroid. Severe laser injuries elicit a significant neutrophil response by 4 hr, suggesting that neutrophils should be an early stage therapeutic target.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Analysis of mode wavefront characteristics for passively Q-switched slab Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Wang, Jie; Hu, Zhiqiu; Su, Likun

    2016-01-01

    The eigenmode of resonators with symmetric circular mirrors used in solid-state lasers is investigated. Further experiments on output beam quality on a passive Q-switched zigzag slab Nd:YAG laser have been performed by adopting Hartmann-Shack and Zernike-mode reconstruction methods. By the means of peak-valley and root mean square errors of the wavefront distribution, each order of Zernike aberrations are achieved accurately. Moreover, the distribution of circle energy in the far-field and corresponding beam evaluation factors can also be obtained by further calculation. Experimental results indicate that the wavefront aberration is mainly concentrated in the first 10 Zernike aberrations, which mainly includes the defocus Z3, the low-order astigmatism Z5, the coma aberration Z6, and the spherical aberration Z10, because of the crystal thermal effect and the intracavity phase perturbation. The method can be used to further analyze the compensation of intracavity aberration and optimal design for such lasers.

  13. A low jitter single frequency Q-switched laser from solid state to optical fiber configuration

    NASA Astrophysics Data System (ADS)

    Wu, Frank F.

    2013-03-01

    This paper will get to the bottom of the mechanism of a superior inject seeding technology, and take it even further, from the solid state laser into the fiber laser configuration. This low jitter, single frequency Q-switched solid state laser with precisely controllable firing time was realized, developed and reported previously, in which the oscillator can output energy of near 100 mJ and the master oscillator power amplifier (MOPA) reaches the output energy of 300 mJ, operating at a wavelength of 1064 nm, with a pulse width of 10 ns and in near single transversal mode. Comparing two existing commercial techniques, ramp-and-fire and pulse-to-pulse buildup time reduction, this report presents a full understanding of using a CW transformed injection seeding method in which this technique is immune to mechanical vibration or thermal expansion, and it is able to precisely control the high peak energy launching time within a nanosecond jitter and achieve single frequency operation at the same time. It is carefully observed that the CW seeding mechanism is similar but not equivalent to a pulsed seeding with pulse width shorter or equal to the ring cavity length. The advantage of the realized regime is that in stable laser operation there is no need to adjust the slave cavity length to match the seeded light longitudinal mode. Therefore, the extremely strict mechanical requirement can be relaxed. It is found that the slave laser frequency follows exactly to the injected seeded laser's frequency which can also provide frequency tuning, control and locking.

  14. Yb:YAG enhanced Cr,Yb:YAG self-Q-switched microchip laser under QCW laser-diode pumping

    NASA Astrophysics Data System (ADS)

    Wang, Guangyu; Chen, Dimeng; Cheng, Ying; Dong, Jun

    2015-05-01

    Enhanced Cr,Yb:YAG self-Q-switched microchip lasers by bonding Yb:YAG crystal have been studied under quasi-continuous-wave (QCW) laser-diode pumping for the first time to our best knowledge. The effects of the pump pulse duration and pump power of the QCW laser-diode on the performance of Yb:YAG/Cr,Yb:YAG microchip lasers have been investigated. The optical efficiency, pulse energy and peak power of the Yb:YAG/Cr,Yb:YAG self-Q-switched laser increase with the pump pulse duration and pump power, and tend to be constant when the pump pulse duration is longer than 1 ms, which is comparable to the fluorescence lifetime of Yb:YAG crystal. Output energy of over 11.7 mJ was obtained at input pump energy of 48.2 mJ; corresponding optical-to-optical efficiency of 24.3% was obtained. Laser pulses with pulse energy of 31 μJ and peak power of 13.3 kW were obtained. The multi-longitudinal modes oscillation around 1030 nm was dominant within the available input pump energy.

  15. Highly efficient high power CW and Q-switched Ho:YLF laser

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, J.

    2015-06-01

    An efficient operation of a Ho:YLF laser pumped by a Tm-doped fibre laser is reported. The research in a continuous-wave (CW) operation was done for two crystals of the same 0.5 at.%Ho dopant concentration and with different lengths (3×3×30 mm3 and 3×3×50 mm3). For an output coupling transmission of 20% and a crystal length of 50 mm, the maximum CWoutput power of 38.9 W for 81.4 W of incident pump power, corresponding to the slope efficiency of 52.3% and optical-to-optical conversion efficiency of 47.8% (determined with respect to the incident pump power) was achieved. The highest opti- cal-to-optical conversion efficiency of 70.2% with respect to the absorbed pump power was obtained. The influence of a heat-sink cooling water temperature on theCWlaser performance was studied. For a Q-switched operation the pulse repe- tition frequency (PRF) was changed from 2 to 10 kHz. The maximum average output power of 34.1 W at the PRF of 10 kHz was obtained for a 50 mm holmium crystal length. For 2 kHz PRF and 71.9 W of incident pump power, pulse energies of 13.7 mJ with a 21 ns FWHM pulse width corresponding to 652 kW peak power were recorded.

  16. High-power widely tunable Q-switched thulium fiber lasers

    NASA Astrophysics Data System (ADS)

    Li, Feng; Zhu, Haibin; Zhang, Yong

    2015-09-01

    Based on acousto-optic modulation and grating diffraction, a high-power-pulsed ~2 μm laser with a wide tunable wavelength is realized in double-clad Tm fibers. A maximum average output power of 35.6 W is obtained with the 6 m fiber, which also provides a maximum pulse energy and peak power of 1.58 mJ and 5.6 kW, respectively. For the 6 m fiber length, a  >20 W average power can be achieved over a 100 nm wavelength tuning range. Shortening the fiber length to 2 m and 1 m can extend the wavelength tuning range further to shorter spectral regimes (1892 nm and 1881 nm). Short fiber length also narrows the Q-switched pulse duration to 90 ns. This kind of high-power, high-pulse-energy, widely tunable, and narrow-bandwidth ~2 μm fiber lasers can find wide applications in various regions.

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

    PubMed

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

    2016-07-25

    In this paper, we demonstrate a high-damage-resistant tungsten disulfide saturable absorber mirror (WS2-SAM) fabricated by magnetron sputtering technique. The WS2-SAM has an all-fiber-integrated configuration and high-damage-resistant merit because the WS2 layer is protected by gold film so as to avoid being oxidized and destroyed at high pump power. Employing the WS2-SAM in an Erbium-doped fiber laser (EDFL) with linear cavity, the stable Q-switching operation is achieved at central wavelength of 1560 nm, with the repetition rates ranging from 29.5 kHz to 367.8 kHz and the pulse duration ranging from 1.269 μs to 154.9 ns. For the condition of the maximum pump power of 600 mW, the WS2-SAM still works stably with an output power of 25.2 mW, pulse energy of 68.5 nJ, and signal-noise-ratio of 42 dB. The proposed WS2-SAM configuration provides a promising solution for advanced pulsed fiber lasers with the characteristics of high damage resistance, high output energy, and wide tunable frequency. PMID:27464082

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

    SciTech Connect

    Taylor, C.R.; Anderson, R.R.; Gange, R.W.; Michaud, N.A.; Flotte, T.J. )

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. A stable 2 μm passively Q-switched fiber laser based on nonlinear polarization evolution

    NASA Astrophysics Data System (ADS)

    He, X.; Luo, A.; Lin, W.; Yang, Q.; Yang, T.; Yuan, X.; Xu, S.; Xu, W.; Luo, Z.; Yang, Z.

    2014-08-01

    A passively Q-switched thulium-doped fiber (TDF) laser based on the nonlinear polarization evolution technique was demonstrated with the central wavelength of 1898.4 nm. With the increasing pump power, the pulse repetition frequency of the Q-switched TDF laser from 87.6 to 110.1 kHz was achieved, while the corresponding pulse duration was changed from 1171 to 785.7 ns. The power instability of the TDF laser was measured to be about ±1.5% during 8 h. In addition, the mode-locked phenomenon was also observed in our all-fiber TDF laser by carefully adjusting the polarization controllers.

  1. Doubly passively Q-switched Yb:NaY(WO4)2 laser with dual-wavelength phenomenon

    NASA Astrophysics Data System (ADS)

    Lan, Ruijun

    2015-06-01

    A diode pumped doubly passively Q-switched \\text{Yb:NaY}≤ft(\\text{W}{{\\text{O}}4}\\right)2/\\text{C}{{\\text{r}}4+}\\text{:YAG}/\\text{GaAs} laser was realized for the first time to our knowledge. Compared with the singly passively Q-switched \\text{Yb:NaY}≤ft(\\text{W}{{\\text{O}}4}\\right)2/\\text{C}{{\\text{r}}4+}\\text{:YAG} laser, this laser can generate a higher repetition rate, and more symmetric and shorter pulses. The highest repetition rate and shortest pulse width was measured to be 82 kHz and 6 ns. At certain pump power, 1022 and 1026 nm dual-wavelength lasers were obtained, and the mechanism of this phenomenon was discussed.

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

    PubMed

    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. PMID:23481809

  3. Passively Q-switched a-cut Nd:GdVO4 self-Raman laser with Cr:YAG

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    A passively Q-switched a-cut Nd:GdVO4 self-Raman solid-state laser with Cr:YAG saturable absorber was firstly demonstrated. The first Stokes at 1173 nm was successfully obtained. At the maximum incident pump power, the pulse width was about 1.8 ns and the repetition rate was 27.5 kHz. 586.5 nm yellow laser output was also realized by use of an LBO frequency doubling crystal.

  4. Diode-pumped high-efficiency high-brightness Q-switched ND:YAG slab laser.

    PubMed

    Armandillo, E; Norrie, C; Cosentino, A; Laporta, P; Wazen, P; Maine, P

    1997-08-01

    A high-efficiency diode-pumped Q-switched Nd:YAG oscillator designed for future spaceborne applications has been demonstrated and characterized. The laser is based on a side-pumped slab geometry and uses an unstable resonator with a radially variable-reflectivity output coupler. The laser provides an output pulse energy of 100 mJ at a 100-Hz repetition rate, with a near-diffraction-limited beam and an overall electrical optical efficiency exceeding 6%. PMID:18185784

  5. The Effect of Anterior Stromal Puncture Using Q-Switched Nd:YAG Laser on Corneal Wound Healing

    PubMed Central

    Hamdy Abdelaziz, Mohamed; Fouad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Taher, Ibraheim Mohyeldin; Abdel- Salam, Ahmed Medhat

    2014-01-01

    Introduction: Recurrent corneal erosion occurs when the wounded corneal epithelium failed to adhere to the underlying stroma. Therefore, this work aimed to assess the effect of treatment of corneal injury using Q- switched Nd:YAG laser. Method: Twenty one New Zealand male rabbits weighing 2-2.5 kg and 3 months old were classified into three main groups. The control group: did not received any treatment (n=3 rabbits). The rest of the animals (n= 18 rabbits), corneal epithelium was injured by syringe needle and blade 15 and divided into:(A) Normal healing group: which was divided into three subgroups (n=3 rabbits each), and the animals were left for normal healing for1 day, 1 week, and 4 weeks respectively, (B) Laser treated group: divided into three subgroups (n=3 rabbit seach) and subjected to anterior stromal puncture using Q-switched Nd: YAG laser on corneal sub-epithelium or superficial stroma, and the animals were left for 1 day, 1 week, and 4 weeksrespectively. After the demonstrated periods, the corneas were isolated for estimation of total protein content, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), total antioxidative capacity (TAC), total oxidative capacity (TOC) and oxidative stress index (OSI). Results: The present results of corneal total protein showed increment in the percentage change in normal healed groups after 1 day, 1 week and 4 weeks by values of 93%, 68% and 39%. In Q-switched Nd: YAG laser treated group the results showed better improvement in corneal protein than normal healed group with percentage changes of 58%, 29%, and 7.5% respectively. In SDS- PAGE, a protein band at 110 KD appeared in the migrating epithelium for both normal healed group and Q-switched Nd:YAG laser treated group with changes in the peaks intensities at middle and low molecular weight regions. Moreover, after 4 weeks the peak at 110 KD disappeared in the wounded epithelium treated with Q-switched Nd:YAG. After four weeks, the OSI in laser

  6. Every Good Virtue You Ever Wanted in a Q-switched Solid-state Laser and More: Monolithic, Diode-pumped, Self-q-switched, Highly Reproducible, Diffraction-limited Nd:yag Laser

    NASA Technical Reports Server (NTRS)

    Chen, Y. C.; Lee, K. K.

    1993-01-01

    The applications of Q-switched lasers are well known, for example, laser radar, laser remote sensing, satellite orbit determination, Moon orbit and 'moon quake' determination, satellite laser communication, and many nonlinear optics applications. Most of the applications require additional properties of the Q-switched lasers, such as single-axial and/or single-transverse mode, high repetition rate, stable pulse shape and pulse width, or ultra compact and rugged oscillators. Furthermore, space based and airborne lasers for lidar and laser communication applications require efficient, compact, lightweight, long-lived, and stable-pulsed laser sources. Diode-pumped solid-state lasers (DPSSL) have recently shown the potential for satisfying all of these requirements. We will report on the operating characteristics of a diode-pumped, monolithic, self-Q-switched Cr,Nd:YAG laser where the chromium ions act as a saturable absorber for the laser emission at 1064 nm. The pulse duration is 3.5 ns and the output is highly polarized with an extinction ratio of 700:1. It is further shown that the output is single-longitudinal-mode with transform-limited spectral line width without pulse-to-pulse mode competition. Consequently, the pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25 percent. This self-stabilization mechanism is because the lasing mode bleaches the distributed absorber and establishes a gain-loss grating similar to that used in the distributed feedback semiconductor lasers. A repetition rate above 5 KHz has also been demonstrated. For higher power, this laser can be used for injection seeding an amplifier (or amplifier chain) or injection locking of a power oscillator pumped by diode lasers. We will discuss some research directions on the master oscillator for higher output energy per pulse as well as how to scale the output power of the diode-pumped amplifier(s) to multi-kilowatt average power.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Numerical Study of Passive Q Switching of a Tm:YAG Laser with a Ho:YLF Solid-State Saturable Absorber

    NASA Astrophysics Data System (ADS)

    Kuo, Yen-Kuang; Chang, Yi-An

    2003-03-01

    In a previous work [Appl. Phys. Lett. 65 , 3060 (1994) we experimentally demonstrated that passive ]Q switching of a 2017-nm, flashlamp-pumped Tm,Cr:YAG laser with a Ho:YLF saturable absorber could be obtained with an internal focusing lens. We numerically investigate the optical performance of the Ho:YLF Q -switched Tm:YAG laser system by solving the coupled rate equations. The simulation results indicate that the results obtained numerically are in good agreement with those obtained experimentally. With typical laser configuration, a Q -switched laser pulse of 35 mJ in 30 ns is obtained.

  9. Generation of Q-switched pulse by Bi2Se3 topological insulator in Yb:KGW laser

    NASA Astrophysics Data System (ADS)

    Hu, Mengting; Liu, Jinghui; Tian, Jinrong; Dou, Zhiyuan; Song, Yanrong

    2014-11-01

    A Q-switched Yb:KGW solid-state laser using topological insulator Bi2Se3 as a saturable absorber was demonstrated experimentally for the first time. The Bi2Se3 saturable absorber was fabricated in a film on a highly reflective mirror. By inserting this into a Yb:KGW laser, the Q-switched operation was obtained. The highest average output power was 439.4 mW and the corresponding repetition rate, pulse width and pulse energy were 166.7 kHz, 1.6 μs and 2.64 μJ, respectively. To our knowledge, this is the highest output power among topological insulator-modulated lasers with topological insulator absorbers.

  10. High-energy directly diode-pumped Q-switched 1617 nm Er:YAG laser at room temperature.

    PubMed

    Wang, Mingjian; Zhu, Liang; Chen, Weibiao; Fan, Dianyuan

    2012-09-01

    We describe high-energy Erbium-doped yttrium aluminum garnet (Er:YAG) lasers operating at 1617 nm, resonantly pumped using 1532 nm fiber-coupled laser diodes. A maximum continuous wave output power of 4.3 W at 1617 nm was achieved with an output coupler of 20% transmission under incident pump power of 29.7 W, resulting in an optical conversion of 14% with respect to the incident pump power. In Q-switched operation, the pulse energy of 11.8 mJ at 100 Hz pulse repetition frequency and 81 ns pulse duration was obtained. This energy is the highest pulse energy reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm. PMID:22941006

  11. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    PubMed Central

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  12. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-05-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.

  13. High-energy resonantly diode-pumped Q-switched Er:YAG laser at 1617 nm

    NASA Astrophysics Data System (ADS)

    Yu, Zhenzhen; Wang, Mingjian; Hou, Xia; Chen, Weibiao

    2016-04-01

    We report high-energy linearly polarized operation of an Er:YAG laser at 1617 nm, resonantly pumped by quasi-continuous-wave 1470-nm laser diodes. A U-shape resonator incorporating two 0.25 at.% Er:YAG rods and an acousto-optic Q-switch was employed. Polarized output with pulse energy of 20.5 mJ and pulse width of 52 ns at a 50 Hz repetition rate was obtained. At the maximum output energy, the output beam quality M 2 was approximately 1.02 and 1.03 in horizontal and vertical directions, respectively. To the best of our knowledge, this polarized pulse energy is the highest ever reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

  14. Watt-level passively Q-switched heavily Er(3+)-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror.

    PubMed

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er(3+)-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  15. Lidar-radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser.

    PubMed

    Vallet, M; Barreaux, J; Romanelli, M; Pillet, G; Thévenin, J; Wang, L; Brunel, M

    2013-08-01

    An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Doppler velocimetry on indoor moving targets. The experimental results are in good agreement with a model based on elementary signal processing theory. In particular, we show experimentally and theoretically that lidar-radar is a promising technique that allows discrimination between translation and rotation movements. Being independent of the laser internal dynamics, this scheme can be applied to any Q-switched laser. PMID:23913058

  16. Continuous-wave and Q-switched operation of a resonantly pumped Ho:YAlO3 laser.

    PubMed

    Yao, Bao-Quan; Duan, Xiao-Ming; Zheng, Liang-Liang; Ju, You-Lun; Wang, Yue-Zhu; Zhao, Guang-Jun; Dong, Qin

    2008-09-15

    We demonstrated continuous-wave (CW) and Q-switched operation of a room-temperature Ho:YAlO(3) laser that is resonantly end-pumped by a diode-pumped Tm:YLF laser at 1.91 microm. The CW Ho:YAlO(3) laser generated 5.5 W of linearly polarized (EII c ) output at 2118 nm with beam quality factor of M(2) approximately 1.1 for an incident pump power of 13.8 W, corresponding to optical-to-optical conversion efficiency of 40%. Up to 1- mJ energy per pulse at pulse repetition frequency (PRF) of 5 kHz, and the maximum average power of 5.3-W with FWHM pulse duration of 30.5 ns at 20 kHz were achieved in Q-switched mode. PMID:18795004

  17. Short-term effects of Q-switched ruby laser on monkey anterior chamber angle

    SciTech Connect

    Bonney, C.H.; Gaasterland, D.E.; Rodrigues, M.M.; Raymond, J.J.; Donohoo, P.

    1982-03-01

    Three Q-switched ruby laser pulses were applied to the trabecular meshwork of 10 monkey eyes. Pulse energies ranging from 20 to 110 mJ were studied. The spot size ranged from 100 to 200 micrometer (in air), and the pulse durations was 28 sec. Gonioscopic examinations showed a graded response from no appreciable change at 20 mJ per pulse to marked disruption of anterior chamber angle structures at 100 mJ or more per pulse. Perfusions done within an hour of treatment showed no consistent alteration of the outflow facility. Scanning electron microscopy demonstrated the graded anterior chamber angle response. No disruption of the angle structures was seen after the 20 mJ treatment, but discrete trabecular damage occurred after treatments with 25 mJ. After pulses equal to or greater than 45 mJ the anterior chamber angle structures were markedly altered. The power density causing extensive tissue disruption was equal to or greater than 150 X 10(8) watts/cm2. In each specimen with an identifiable trabecular lesion, tissue debris and endothelial edema were found on the adjacent inner surface of the cornea. Tearing of Descemet's membrane next to the trabecular meshwork occurred with the 100 mJ pulses.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Removal of tattoos by q-switched laser: variables influencing outcome and sequelae in a large cohort of treated patients.

    PubMed

    Bencini, Pier Luca; Cazzaniga, Simone; Tourlaki, Athanasia; Galimberti, Michela Gianna; Naldi, Luigi

    2012-12-01

    OBJECTIVE To analyze variables affecting the treatment course and prognosis of Q-switched laser tattoo removal. DESIGN Observational prospective cohort study. SETTING The study was carried out in a referral center for surgery and laser surgery in Milan. PARTICIPANTS Of 397 consecutive patients initially enrolled from January 1, 1995, to December 31, 2010, 352 patients (201 men and 151 women; median age, 30 years) were included in the analysis. INTERVENTION All patients were treated by the same investigator with Q-switched 1064/532-nm Nd:YAG laser and Q-switched 755-nm alexandrite laser according to tattoo colors. Laser sessions were scheduled at 6-week or longer intervals. MAIN OUTCOME MEASURES Successful therapy was defined as removal of the tattoo, with no adverse effects other than transient hypochromia or darkening. RESULTS The cumulative rates of patients with successful tattoo removal were 47.2% (95% CI, 41.8%-52.5%) after 10 sessions and 74.8% (95% CI, 68.9%-80.7%) after 15 sessions. Smoking, the presence of colors other than black and red, a tattoo larger than 30 cm2, a tattoo located on the feet or legs or older than 36 months, high color density, treatment intervals of 8 weeks or less, and development of a darkening phenomenon were associated with a reduced clinical response to treatment. CONCLUSIONS To our knowledge, this study is the first to formally assess prognostic factors for effective tattoo removal by Q-switched laser. Several variables influence response rates and should be considered when planning tattoo removal treatments. PMID:22986584

  20. High-peak-power single-oscillator actively Q-switched mode-locked Tm3+-doped fiber laser and its application for high-average output power mid-IR supercontinuum generation in a ZBLAN fiber.

    PubMed

    Kneis, Christian; Donelan, Brenda; Manek-Hönninger, Inka; Robin, Thierry; Cadier, Benoît; Eichhorn, Marc; Kieleck, Christelle

    2016-06-01

    A single-oscillator actively Q-switched mode-locked (QML) thulium-doped silica fiber laser is presented and used to pump a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber for mid-infrared (mid-IR) supercontinuum (SC) generation. The fiber laser provided high-peak-power levels directly from the oscillator delivering single mode-locked pulse energies up to 48 μJ, being 2-4 orders of magnitude higher than conventional continuous wave mode-locked lasers. By pumping a ZBLAN fiber specially designed for high-output-power SC generation, 7.8 W have been achieved in all spectral bands with a spectrum extending to 4.2 μm. PMID:27244410

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

    SciTech Connect

    Mukhopadhyay, Pranb K. Gupta, Pradeep K.; Singh, Chandra Pal; Singh, Amarjeet; Sharma, Sunil K.; Bindra, Kushvinder S.; Oak, Shrikant M.

    2015-03-15

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

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

    PubMed

    Mukhopadhyay, Pranb K; Gupta, Pradeep K; Singh, Chandra Pal; Singh, Amarjeet; Sharma, Sunil K; Bindra, Kushvinder S; Oak, Shrikant M

    2015-03-01

    We have constructed an Yb-doped fiber laser in all-normal-dispersion configuration which can be independently operated in Q-switched or modelocked configuration with the help of a simple fiber optic ring resonator (FORR). In the presence of FORR, the laser operates in Q-switched mode producing stable pulses in the range of 1 μs-200 ns with repetition rate in the range of 45 kHz-82 kHz. On the other hand, the laser can be easily switched to mode-locked operation by disjoining the FORR loop producing train of ultrashort pulses of ∼5 ps duration (compressible to ∼150 fs) at ∼38 MHz repetition rate. The transmission characteristics of FORR in combination with the nonlinear polarization rotation for passive Q-switching operation is numerically investigated and experimentally verified. The laser can serve as a versatile seed source for power amplifier which can be easily configured for application in the fields that require different pulsed fiber lasers. PMID:25832207

  3. ACTIVE MEDIA: Chromium-activated forsterite crystal as the passive Q switch in the cavity of an Nd:YAG laser and as the active medium in an Nd:YAG—Cr:forsterite laser system

    NASA Astrophysics Data System (ADS)

    Skripko, G. A.; Tarazevich, I. G.

    1996-03-01

    An investigation was made of the generation and self-modulation of the λ = 1.064 and 1.25 μm radiation in an Nd:YAG—Cr:forsterite laser system. The advantages of this system over those with traditional methods were demonstrated. The feasibility of self-control of the rate of pumping of the Cr:forsterite crystal was revealed and recommendations on optimisation of the system were developed.

  4. Compact, Passively Q-Switched Nd:YAG Laser for the MESSENGER Mission to the Planet Mercury

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

    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 < 0.001) and 54.13 ± 6.01 (P < 0.001), respectively. Patient and the physician global assessment score showed that 26 (74.3%) and 20 (57.14%) patients, respectively, had >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. Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

    NASA Astrophysics Data System (ADS)

    Li, J. F.; Luo, H. Y.; He, Y. L.; Liu, Y.; Zhang, L.; Zhou, K. M.; Rozhin, A. G.; Turistyn, S. K.

    2014-06-01

    A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 µJ with a pulse width of 1.68 µs and signal-to-noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 µm. To the best of our knowledge, this is the first 3 µm region SESAM-based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

  7. Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Luo, Hongyu; He, Yulian; Liu, Yong; Luo, Binbin; Sun, Zhongyuan; Zhang, Lin; Turitsyn, Sergei K.

    2014-05-01

    A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 μJ with a pulse width of 1.68 μs and signal to noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 μm. To the best of our knowledge, this is the first 3 μm region SESAM based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

  8. Integrated electro-optic Q switching in a domain-inverted Nd:LiTaO3 laser

    NASA Astrophysics Data System (ADS)

    Abedin, Kazi Sarwar; Tsuritani, Takehiro; Sato, Manabu; Ito, Hiromasa; Shimamura, Kiyoshi; Fukuda, Tsuguo

    1995-10-01

    We report a novel integrated Q -switched laser constructed from a bulk domain-inverted single Nd:LiTaO3 crystal that combines the laser gain and the electro-optic effect. The Q of the cavity is controlled electro-optically by exploitation of the deflection that occurs at the boundary of two oppositely directed domains under the application of an electric field. The integrated Q -switching element, with dimensions of 4.1mm \\times 4.6 mm \\times 1 mm , generates 22-ns pulses at 1.08 mu m with a peak power of 64 W and an operating voltage of \\similar 600 V . The output is seen to be completely free from prelasing or afterpulsing.

  9. Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber

    PubMed Central

    Zhang, M.; Hu, Guohua; Hu, Guoqing; Howe, R. C. T.; Chen, L.; Zheng, Z.; Hasan, T.

    2015-01-01

    We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm2 saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications. PMID:26657601

  10. Q-switched mode-locked and azimuthally polarized Nd:GdVO4 laser with semiconductor saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Hong, Kun-Guei; Hung, Bi-Jin; Lin, Shih-Ting; Wei, Ming-Dar

    2016-06-01

    A Q-switched mode-locked Nd:GdVO4 laser with azimuthal polarization was generated using a semiconductor saturable absorber mirror. On the basis of the birefringence of the laser crystal inducing different equivalent lengths for ordinary and extraordinary rays, beams were azimuthally polarized around the edge of a stable cavity region. At a pump power of 9 W, the repetition rate and width for the Q-switched envelope were 318 kHz and 0.91 µs, and the mode-locked pulse repetition rate and pulse width were 455 MHz and 65 ps, respectively. The degree of polarization was controllable up to 95.4 ± 1.4%.

  11. S-band Q-switched fiber laser using molybdenum disulfide (MoS2) saturable absorber

    NASA Astrophysics Data System (ADS)

    Ahmad, Harith; Afiq Ismail, Mohd; Suthaskumar, Muneswaran; Cheak Tiu, Zian; Wadi Harun, Sulaiman; Zamani Zulkifli, Mohd; Samikannu, Sathiyan; Sivaraj, Sivabalan

    2016-03-01

    In this letter, a molybdenum disulfide (MoS2) saturable absorber (SA) is fabricated using a simple drop cast method to generate Q-switched fiber laser operating in the S-band region (1460 nm-1530 nm). The MoS2 solution was prepared using the liquid phase exfoliation (LPE) method where MoS2 crystals were added into dimethylformamide (DMF) solvent and subsequently sonicated and centrifuged. They were then repeatedly dripped onto fiber ferrules and dried in an oven. The resultant Q-switched fiber laser starts with some physical disturbance when the pump power was set at 40 mW and continues to operate until the pump power reaches 120 mW. The resultant repetition rate varies with pump power between 27.17 to 101.17 kHz while the changes in pulse widths are from 3.0 to 1.4 μs.

  12. Lithium niobate Q-switch to prevent pre-lasing of high gain lasers operating over a wide temperature range

    NASA Astrophysics Data System (ADS)

    Jundt, Dieter H.; MacKay, Peter E.

    2015-02-01

    Because of its ease of growth and large electro-optic effect, lithium niobate is the preferred choice for Q-switching mobile lasers. Temperature-induced pyro-electric charges however may lead to premature lasing. We manufactured and characterized temperature-stable LN Q-switch. A thermo-chemical anneal was performed creating a conductive material layer 0.5mm thick with increased conductivity. While this increases optical insertion loss by a few percent, this is tolerable in high gain lasers. We present details of treatment, the surface charge creation and dissipation mechanism and the setup used to assess the cold-performance used to demonstrate improved charge dissipation when compared to untreated crystals.

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

    NASA Astrophysics Data System (ADS)

    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. 183 WTEM00 mode acoustic-optic Q-switched MOPA laser at 850 kHz.

    PubMed

    Liu, Qiang; Yan, Xingpeng; Fu, Xing; Gong, Mali; Wang, Dongsheng

    2009-03-30

    We report a high-power, high-repetition-rate TEM00 mode MOPA laser using acoustic-optic Q-switching. Seed laser from the dual-end- pumped Nd:YVO4 oscillator was scaled up to 183.5 W average power at 850 kHz after behind amplified by the four-stage power amplifiers. The stable Q-switching operation worked at different pulse repetition rate from 60 kHz to 850 kHz while the pulse duration increased from 12.8 ns to 72 ns. The beam quality was near diffraction-limit with M2 factors measured as M2x = 1.28 and M2y = 1.21. In CW operation, 195 W TEM00 mode output was achieved corresponding to the total optical-optical efficiency of 44.7% and the absorbed pump power to output power efficiency of 53.3% respectively. PMID:19333332

  15. 145-watt high beam quality bidirectional voltage-supplied Q-switched Nd∶YAG master oscillator power amplifier laser

    NASA Astrophysics Data System (ADS)

    Bai, Zhenxu; Long, Mingliang; Chen, Liyuan; Chen, Meng; Li, Gang

    2013-02-01

    We present a high compact structure laser diode (LD) side-pumped all-solid-state Q-switched master oscillator power amplifier (MOPA) laser system with high beam quality. Bidirectional voltage-supplied Q-switched and MOPA technologies were introduced in the design. An in-center wavelength of 1064 nm with pulse width adjustability from 5 to 18 ns was obtained at the repetition rate of 500 Hz. Through multistage Nd∶YAG amplifiers at the pulse width of 6 ns, the oscillator was scaled up to 145 W and the corresponding peak power reached 48.3 MW with single pulse energy fluctuation less than 0.45% in 1 h operation.

  16. Experimental investigation on laser milling of aluminium oxide using a 30 W Q-switched Yb:YAG fiber laser

    NASA Astrophysics Data System (ADS)

    Leone, C.; Genna, S.; Tagliaferri, F.; Palumbo, B.; Dix, M.

    2016-01-01

    In the present study, laser milling tests were carried out on aluminium oxide (Al2O3) plate, 3 mm in thickness, using a Q-Switched 30 W Yb:YAG fiber laser. A systematic approach based on Design of Experiment (DoE) has been successfully adopted with the aim to detect which and how the process parameters affect the laser beam-material interaction, and to explain the effect of the process parameters on the material removal rate and surface quality. The examined process parameters were the laser beam scan speed, the pulse frequency, the total energy released for surface unit, the distance between two consecutive scan lines and the scanning strategy. A full factorial design and ANalysis Of VAriance (ANOVA) were applied for the results analysis. Finally, the various effects of the process parameters on the material removal rate and surface roughness have been analysed and discussed.

  17. Application systems for the intracorporal laser-induced shockwave lithotripsy using the Nd:YAG Q-switched laser

    NASA Astrophysics Data System (ADS)

    Frank, Klaus H.; Eichenlaub, M.; Hessel, Stefan F. F.; Wondrazek, Fritz

    1990-06-01

    For the laser-induced shockwave lithotripsy the electromagnetic energy of a laser light pulse is converted intracorporally into the acoustic energy of a shock wave. The lithotriptor is based on a specially developed, Q-switched Nd:YAG laser whose high power light pulses (70 mJ, 25 ns) are coupled into a flexible quartz fiber of 600 pim core diameter. Using focussing elements energy densities higher than 6 1O J m2 can be achieved resulting in an optical breakdown in water followed by a shock wave. As a result of different absorption mechanisms the breakdown threshold can be decreased by placing a metallic target into the laser beam. The different shockwave formations of such optomechanical transducers have been measured. First clinical applications have been performed.

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

    PubMed

    Nisar, Mahrukh S; Iyer, Karthik; Brodell, Robert T; Lloyd, Jenifer R; Shin, Thuzar M; Ahmad, Asad

    2013-01-01

    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 laser proved to provide effective clearing of the minocycline hyperpigmentation requiring just 2 treatments, with minimal treatment discomfort and down time. PMID:23754872

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

    NASA Astrophysics Data System (ADS)

    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.

  20. CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1

    SciTech Connect

    Bibeau, C.; Beach, R.; Ebbers, C.; Emanuel, M.; Skidmore, J.

    1997-02-19

    Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 226 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.

  1. Cr4 + :Gd3Sc2Ga3O12 passive Q-switch for the Cr3 + :LiCaAlF6 laser

    NASA Astrophysics Data System (ADS)

    Kuo, Yen-Kuang; Yang, Yang; Birnbaum, Milton

    1994-05-01

    A Cr4+:Gd3Sc2Ga3O12 (Cr4+:GSGG) broad-band saturable absorber has been demonstrated to be an excellent passive Q-switch for the flashlamp-pumped tunable Cr3+:LiCaAlF6 (Cr:LiCAF) laser at room temperature. A single Q-switched laser output pulse of 11 mJ in energy and 37 ns in duration at 778 nm was obtained in a nonoptimized laser.

  2. Maximum value of the pulse energy of a passively Q-switched laser as a function of the pump power.

    PubMed

    Li, Jianlang; Ueda, Ken-ichi; Dong, Jun; Musha, Mitsuru; Shirakawa, Akira

    2006-07-20

    The finite recovery time Ts of the bleached absorber is presented as one of the possible mechanisms accounting for the increase-maximum-decrease in pulse energy E with the pumping rate Wp in cw-pumped passively Q-switched solid-state lasers, by analytically evaluating the sign of the derivative partial differentialE/ partial differentialWP. The results show that, in the low pump regime (T>Ts, T is the interpulse period), the initial population density ni remains constant, the final population density nf decreases with Wp, and this results in a monotonic increase of E with Wp. In the high pump regime (Tlaser passively Q switched by a Cr4+:YAG absorber is demonstrated to confirm this model. The theoretical model is also applied to the analysis of three previously reported passive Q switching solid-state [Nd:GdVO4, Nd+:LaSc3(BO3)4 (Nd+:LSB), and Nd:YAG] lasers experiments. PMID:16826274

  3. Intracavity KTP OPO pumped by a doubly Q-switched laser with AOM and a monolayer graphene saturable abosorber

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    An intracavity KTiOPO4 (KTP) optical parametric oscillator (IOPO) pumped by a doubly Q-switched YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a monolayer graphene saturable absorber has been realized for the first time. The average output power, the pulse duration, single pulse energy and the peak power of signal light versus incident pump power have been measured. At an incident pump power of 11.7 W and an AOM repetition rate of 10 kHz, the shortest pulse duration of 1.24 ns was obtained, corresponding to a single pulse energy of 9.5 μJ and a peak power of 7.9 kW. In comparison, the doubly IOPO (DIOPO) pumped by doubly Q-switched laser with AOM and graphene saturable absorber can generate pulses with narrower pulse width and higher peak power than the singly IOPO (SIOPO) pumped only by AOM Q-switched laser.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. 26-mJ pulse energy Q-switched large-pitch fiber laser system with excellent beam quality

    NASA Astrophysics Data System (ADS)

    Jansen, Florian; Stutzki, Fabian; Liem, Andreas; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2012-02-01

    In this work we report on what we believe is the highest pulse energy obtained from an effectively single-mode Qswitched fiber laser system to date. This result has been obtained using rare-earth-doped double-clad large-pitch fibers which are able to delocalize the higher-order transverse modes from the active region of the core. We have built an actively Q-switched oscillator consisting of a 1.3m long large-pitch fiber with a mode field diameter of 50μm. This oscillator delivered pulses with 500μJ energy at a repetition rate of 5kHz. These seed pulses have been amplified in two fiber amplifiers which were pumped at 976nm. The pre-amplifier employs a 1.2m long large-pitch fiber with a mode field diameter of 80μm and delivered 3.5mJ pulse energy. Then, a 135μm core diameter large-pitch fiber was used as booster amplifier. Under high power operation the mode field diameter of this fiber is ~100μm. The setup can deliver average powers of up to 130W, resulting in 26mJ pulses with pulse durations of ~50ns. Additionally, since this is an effective single-mode laser system, the beam quality is close to the diffraction-limit.

  6. Tunable diode laser-pumped Tm,Ho:YLF laser operated in continuous-wave and Q-switched modes

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Tunable continuous-wave and pulsed laser output was obtained from a Tm-sensitized Ho:YLiF4 crystal at subambient temperatures when longitudinally pumped with a diode laser array. A conversion efficiency of 42 percent and slope efficiency of approximately 60 percent relative to the absorbed pumped power have been achieved at a crystal temperature of 275 K. The emission spectrum was etalon tunable over a range of 16/cm centered at 2067 nm with fine tuning capability of the transition frequency with crystal temperature at measured rate of -0.03/cm/K. Output energies of 0.22 mJ per pulse and 22 ns pulse duration were recorded at Q-switch frequencies that correspond to an effective upper laser level lifetime of 6 ms, and a pulse energy extraction efficiency of 64 percent.

  7. Q-switched Tm3+-doped fiber laser with a micro-fiber based black phosphorus saturable absorber

    NASA Astrophysics Data System (ADS)

    Wang, Yazhou; Li, Jianfeng; Han, Lian; Lu, Rongguo; Hu, Yunxiao; Li, Zhuo; Liu, Yong

    2016-06-01

    We report a passively Q-switched Tm3+-doped fiber laser using a black phosphorus deposited micro-fiber (BPDMF) as a saturable absorption (SA) device for the first time. The BPDMF prepared by depositing black phosphorus (BP) on the micro-fiber waist with heat convention effect and optical tweezer effect has a measured modulation depth of 40.2% and a nonsaturable loss of 55.9%. By employing this device in an all-fiber ring cavity, a stable Q-switched pulse train at 1948 nm was achieved with a repetition rate from 12.5 to 28.1 kHz and a pulse width from 15.1 to 5.6 μs, respectively.

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

    PubMed

    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. PMID:26906366

  9. A continuous-wave and passively Q-switched Nd:LaGGG laser at 937 nm

    NASA Astrophysics Data System (ADS)

    Li, Z.-Y.; Ying, H.-Y.; Yang, H.; He, J.-L.

    2013-10-01

    A diode-end-pumped continuous-wave (CW) and passively Q-switched Nd:LaGGG (GGG: gadolinium gallium garnet) laser at about 937 nm was demonstrated for the first time. The maximum CW output power of 540 mW was obtained with the optical-optical conversion efficiency of 3.2% and the slope efficiency of 4.4%. A V3+:YAG (yttrium aluminum garnet) saturable absorber with the initial transmission of 97% was used for the passive Q-switching regime. The shortest pulse width was achieved as 500 ns with the pulse repetition rate of 96 kHz. The corresponding single-pulse energy and pulse peak power were determined as 1.56 μJ and 3.12 W, respectively.

  10. Using a black phosphorus saturable absorber to generate dual wavelengths in a Q-switched ytterbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Rashid, F. A. A.; Azzuhri, Saaidal R.; Salim, M. A. M.; Shaharuddin, R. A.; Ismail, M. A.; Ismail, M. F.; Razak, M. Z. A.; Ahmad, H.

    2016-08-01

    Using a few-layer black phosphorus (BP) thin film that acts as a saturable absorber (SA) in an ytterbium-doped fiber laser setup, we experimentally demonstrated a passively dual-wavelength Q-switching laser operation. The setup also incorporated a D-shaped polished fiber as a wavelength selective filter. As the SA was used in the ring cavity, a dual-wavelength Q-switch produced consistent outputs at 1038.68 and 1042.05 nm. A maximum pulse energy of 2.09 nJ with a shortest pulse width of 1.16 µs was measured for the achieved pulses. In addition, the repetition rate increased from 52.52 to 58.73 kHz with the increment of the pump level. Throughout the measurement process, the results were obtained consistently and this demonstrates that the BP film is a very good candidate to produce Q-switching pulses for the 1 micron region.

  11. Efficient diode-pumped acousto-optic Q-switched Er:Yb:GdAl(3)(BO(3))(4) pulse laser at 1522  nm.

    PubMed

    Chen, Y J; Lin, Y F; Huang, J H; Gong, X H; Luo, Z D; Huang, Y D

    2015-11-01

    End-pumped by a continuous-wave 976 nm diode laser, efficient 1522 nm laser operation was demonstrated in an Er:Yb:GdAl(3)(BO(3))(4) crystal when a sapphire crystal was used as a heat diffuser. A continuous-wave 1522 nm laser with a maximum output power of 750 mW and slope efficiency of 36% was realized at an absorbed pump power of 4.1 W. The pulse performances of an acousto-optic Q-switched laser with various repetition frequencies were investigated in detail. In a repetition frequency range of 1-10 kHz, 1522 nm pulse lasers with a slope efficiency of about 10%, peak output power at the kilowatt level, and width of about 50 ns were first obtained in an Er:Yb:GdAl(3)(BO(3))(4) crystal pumped by a continuous-wave diode laser. The results indicate that the crystal is a promising gain medium for an actively Q-switched 1.5 μm laser. PMID:26512485

  12. Repetitive Q-switching of a CW Nd:YAG laser using Cr{sup 4+}:YAG saturable absorbers

    SciTech Connect

    Shimony, Y.; Burshtein, Z.; Ben-Amar Baranga, A.; Kalisky, Y.; Strauss, M.

    1996-02-01

    Repetitive Q-switching of a CW pumped Nd:YAG laser using a Cr{sup 4+}:YAG saturable absorber was achieved for the first time, providing pulses 80--300 ns wide (FWHM) with repetition rates ranging between 2 and 29 kHz. Different ranges of repetition rates and pulse widths are obtained by using absorbers of different optical densities. Satisfactory quantitative description of the experimental results is obtained by a full numerical solution of the system rate equations according to the theory of Powell and Wolga. These equations involve the dynamics of the laser population inversion, the absorber state population, and the photon density in the laser cavity.

  13. Continuous-wave and passively Q-switched 1.06 μm ceramic Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    He, Ying; Ma, Yufei; Li, Jiang; Li, Xudong; Yan, Renpeng; Gao, Jing; Yu, Xin; Sun, Rui; Pan, Yubai

    2016-07-01

    In this paper, a diode-pumped continuous-wave and passively Q-switched 1.06 μm laser with gain medium of ceramic was demonstrated. Laser output characteristics using Nd:YAG ceramics with different doping concentrations of 1.0%, 2.0%, and 4.0% were studied. A maximum output power of 7.74 W with optical efficiency of 51.6% was obtained through the optimization of the coupler's transmission. By using Cr4+:YAG crystals with initial transmissions of 80% and 90% as saturable absorbers, the pulsed ceramic Nd:YAG laser performance was investigated.

  14. Theory and Engineering Design Aspects of a Mini Diode-Pumped Q-Switch Er: Glass Laser for Space Applications

    NASA Astrophysics Data System (ADS)

    Sankar, N. Siva; Ramalingam, A.; Raja, V. L. N. Sridhar; Laxmiprasad, A. S.

    2011-10-01

    The invention of the laser, with its precise wavelength and beam divergence characteristics, coupled with the techniques like q-switching, mode locking to produce ultra-short pulses has been influencing the era of space technology. Space agencies worldwide are equipping satellites with laser transmitters in the hope of achieving crucial and vital tasks. Though, both laser technology and space operations have matured substantially in the recent decades, offering synergistic possibilities of using lasers from space-based platforms, development of a reliable laser sources meeting the space mission types and constraints is still the current quest. This paper especially focuses on the conceptualization and engineering design aspects of developing a miniaturized diode pumped, passive q-switch Er: Glass laser capable of delivering pulses of energy 3 mJ, pulse width of 7 ns at a repetition rate of 1 Hz and operating wavelength of 1535 nm. This paper sheds the light also on the selected resonator configurations, pump geometries and theoretical estimations that were performed in selection of the resonator elements keeping the miniaturization as the prime concern. Simulations of the non-linear effects like pump energy distribution, thermal lensing of the configured laser resonator design are done by employing various laser cavity and design analysis software.

  15. Laser based analysis using a passively Q-switched laser employing analysis electronics and a means for detecting atomic optical emission of the laser media

    DOEpatents

    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.

  16. 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.

    PubMed

    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. PMID:26861980

  17. 456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction.

    PubMed

    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. PMID:25927746

  18. Tm:KLu(WO(4))(2) microchip laser Q-switched by a graphene-based saturable absorber.

    PubMed

    Serres, Josep Maria; Loiko, Pavel; Mateos, Xavier; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc

    2015-06-01

    We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a Tm:KLu(WO4)2 crystal cut along the Ng dielectric axis. This laser generates a maximum average output power of 310 mW with a slope efficiency of 13%. At a repetition rate of 190 kHz the shortest pulses with 285 ns duration and 1.6 µJ energy are achieved. PMID:26072779

  19. Partial unilateral lentiginosis treated with alexandrite Q-switched laser: case report and review of the literature.

    PubMed

    Pretel, Maider; Irarrazaval, Isabel; Aguado, Leyre; Lera, José Miguel; Navedo, María; Giménez de Azcárate, Ana

    2013-08-01

    Partial unilateral lentiginosis (PUL) is a rare pigmentary disorder characterized by multiple lentigines grouped within an area of normal skin, often in a segmental pattern and appearing at birth or in childhood. There is no established standard treatment for this condition. We present two cases of PUL succesfully treated with alexandrite Q-switched laser. In our cases, this laser proved to be a safe and effective treatment for cosmetically disfiguring lentigines. Special precautions are needed when treating dark-skinned patients because side effects are more likely. We propose that this modality be considered in the treatment of this rare disorder. PMID:23384078

  20. A frequency-locked and frequency-doubled, hybrid Q-switched Yb:KYW laser at 515 nm with a widely adjustable repetition rate

    NASA Astrophysics Data System (ADS)

    Tjörnhammar, S.; Zukauskas, A.; Canalias, C.; Pasiskevicius, V.; Laurell, F.

    2015-09-01

    We demonstrate a compact wavelength-stabilized, frequency-doubled Yb-doped double-tungstate laser with widely tunable repetition rate, spanning from 35 Hz to 3 kHz obtained by hybrid Q-switching. The Q-switching unit consisted of a combination of a passive Cr:YAG crystal and an opto-mechanical active intensity modulator. The fundamental wavelength was locked at 1029 nm with a volume Bragg grating, and the pulse length and energy were 42 ns and 250 µJ, respectively. As the laser was stabilized with the VBG and the opto-mechanical modulator, the frequency instability was reduced six times from free running down to 0.29 %. Frequency doubling was done extra-cavity in PPKTP, and a repetition rate-independent conversion efficiency of 63 % was obtained. The controllable repetition rate together with stable temporal and spatial characteristics makes this laser a suitable candidate in many biology-related experiments, as a pump source for in vivo excitation of fluorophores, e.g., pumping of "living lasers" and matrix-assisted laser desorption/ionization mass spectroscopy.

  1. Comparison of different pulsed and Q-switched solid state laser systems for endoscopic laser-induced shockwave lithotripsy: performance and laser/stone interactions

    NASA Astrophysics Data System (ADS)

    Steiger, Erwin

    1990-06-01

    At present the laser induced shock wave lithotripsy (LISL) of urinary and biliary stones via fiber optic beam delivery is governed by two competing' laser systems: The flashlamp-pumped pulsed dye laser and the Q-switched Nd:YAG laser. The pulsed radiation of the dye system with pulse durations in the 1-2 .tsec region can be easily transmitted through extremely flexible fused silica fibers with core diameters of only 200 im whilst the Q-switched Nd:YAG laser with pulselengths of 5-25 nsec needs fibers with more than 400 tm core diameter. The dye laser releases acoustic shock waves for fragmentation simply by stone contact, the Q-switched Nd:YAG produces these waves in the surrounding aqueous medium by laser induced optical breakdown (LIB) when refocused by optical means or through additional metal absorbers, i.e. opto - mechanical couplers. We report on the system performances and laser/stone interactions of two alternative solid-state laser systems with variable pulselengths in the range of 1.7 - 30 sec and 30 - 1000 nsec, respectively: The pulsed psec-Nd:YAG laser and the Q-switched alexandrite laser. Regarding the endoscopic laser lithotripsy of urinary and biliary stones in the ureter or common bile duct, respectively, the laser energy delivery system, i.e. the optical fiber; is the most stressed part. Therefore we used long-pulse solid-state laser systems like the pulsed Nd:YAG laser with a pulse-slicing unit and a pulselength-tunable Q-switched alexandrite laser and studied fragmentation of synthetic plaster samples as well as urinary and biliary stones. The radiation of both laser systems can be effectively transmitted via standard 200 im core diameter optical quartz fibers what is absolutely necessary when used in conjunction with small caliber rigid or flexible endoscopes. As a compact and reliable solid-state system the alexandrite laser lithotripter is much less expensive than an extracorporeal shock wave lithotripter with the same fragmentation results

  2. Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

    NASA Technical Reports Server (NTRS)

    Choi, Young S.; Kim, Kyong H.; Whitney, Donald A.; Hess, Robert V.; Barnes, Norman P.; Bair, Clayton H.; Brockman, Philip

    1989-01-01

    A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid

  3. Self-Q-switched ytterbium-doped fibre laser with intracavity spectral conversion

    SciTech Connect

    Grukh, Dmitrii A; Levchenko, A E; Kurkov, Andrei S; Paramonov, Vladimir M

    2005-05-31

    A pulsed fibre laser is fabricated which is based on an active fibre with a multielement cladding and an additional single-mode fibre providing nonlinear feedback. The peak output power of the laser is {approx}1 kW for 20-ns pulses. The emission spectra of the laser with additional fibres having different nonlinear and dispersion properties are investigated. (fibre lasers)

  4. Q-switched quasi-phase-matched self-frequency doubling and summing in a laser based on a periodically poled Nd : Mg : LiNbO{sub 3} crystal

    SciTech Connect

    Laptev, G D; Novikov, Aleksei A; Firsov, V V

    2004-03-31

    Quasi-phase-matched second harmonic generation at 542 nm by self-frequency doubling laser radiation at 1084 nm and quasi-phase-matched sum-frequency generation at 464 nm by summing frequencies of laser radiation and of nonabsorbed fraction of diode laser pump radiation at 810 nm are experimentally achieved. These processes are realised in a Q-switched laser based on a periodically poled active nonlinear Nd : Mg : LiNbO{sub 3} crystal. (nonlinear optical phenomena)

  5. Yb:YAG thin disk laser passively Q-switched by a hydro-thermal grown molybdenum disulfide saturable absorber

    NASA Astrophysics Data System (ADS)

    Zhan, Yi; Wang, Li; Wang, Jie Yu; Li, Hong Wei; Yu, Zhen Huang

    2015-02-01

    We demonstrate a passively Q-switched Yb:YAG thin disk solid-state laser based on nanoflake MoS2 as a saturable absorber. MoS2 is synthesized by a hydro-thermal process. The prepared MoS2 is transferred onto the BK7 glass for ease-of-use in the solid-state laser as a saturable absorber. The average output power could reach up to 250 mW, center wavelength 1030 nm corresponding to a pulse width, a pulse repetition rate, and a per pulse energy of 12 μs, 17 kHz, and 15 μJ, respectively. Our results show that nanoflake MoS2 could be a promising saturable absorber for Q-switching solid-state lasers. The over saturation of the MoS2 saturable absorber at a high pump strength limit in a solid-state laser could be also effective for high power operation.

  6. Q-switched-like soliton bunches and noise-like pulses generation in a partially mode-locked fiber laser.

    PubMed

    Wang, Zhenhong; Wang, Zhi; Liu, Yan-Ge; Zhao, Wenjing; Zhang, Hao; Wang, Shangcheng; Yang, Guang; He, Ruijing

    2016-06-27

    We report an intermediate regime between c.w. emission and noise-like pulses (NLPs) regime in an Er-doped partially mode-locked fiber laser with nonlinear polarization rotation. In this regime, the soliton bunches stochastically turn up from a quasi-cw background in the Q-switched-like envelope. The soliton bunches normally last for tens or hundreds of intracavity round-trips. When the soliton bunches vanish, typical NLPs chains are generated sporadically at location where the soliton bunches collapses. These results would be helpful to understand the generation and property of the NLPs regime. PMID:27410624

  7. 0.7 MW output power from a two-arm coherently combined Q-switched photonic crystal fiber laser.

    PubMed

    Rosenstein, Boris; Shirakov, Avry; Belker, Daniel; Ishaaya, Amiel A

    2014-03-24

    We demonstrate a high peak power, Q-switched pulsed, intracavity coherently combined fiber laser system. The system is based on two Yb-doped, rod-type, photonic crystal fibers which are passively phase-locked and combined into the single output beam in a power oscillator configuration. Experimental evidence indicate that this oscillator system provides record high peak power of ∼ 0.7 MW with pulse duration of ∼ 10 ns at 1 kHz repetition rate. The measured beam quality shows near-diffraction-limited operation of the coherently combined system. PMID:24663989

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

    PubMed

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

    2014-06-30

    An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser. PMID:24977828

  9. Electro-optic Q-switch

    NASA Technical Reports Server (NTRS)

    Zou, Yingyin (Inventor); Chen, Qiushui (Inventor); Zhang, Run (Inventor); Jiang, Hua (Inventor)

    2006-01-01

    An electro-optic Q-switch for generating sequence of laser pulses was disclosed. The Q-switch comprises a quadratic electro-optic material and is connected with an electronic unit generating a radio frequency wave with positive and negative pulses alternatively. The Q-switch is controlled by the radio frequency wave in such a way that laser pulse is generated when the radio frequency wave changes its polarity.

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

    PubMed

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

    2015-05-01

    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. In this work, 2D tungsten disulfide (WS2) based saturable absorber (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 discovered in the WS2-PVA SA at the telecommunication wavelength 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 few-layer WS2 nanosheets embedded in PVA thin film are promising nonlinear optical materials for ultrafast photonic applications as a mode locker or Q-switcher. PMID:25969240

  11. Analytical solution of the transient temperature profile in gain medium of passively Q-switched microchip laser.

    PubMed

    Han, Xiahui; Li, Jianlang

    2014-11-01

    The transient temperature evolution in the gain medium of a continuous wave (CW) end-pumped passively Q-switched microchip (PQSM) laser is analyzed. By approximating the time-dependent population inversion density as a sawtooth function of time and treating the time-dependent pump absorption of a CW end-pumped PQSM laser as the superposition of an infinite series of short pumping pulses, the analytical expressions of transient temperature evolution and distribution in the gain medium for four- and three-level laser systems, respectively, are given. These analytical solutions are applied to evaluate the transient temperature evolution and distribution in the gain medium of CW end-pumped PQSM Nd:YAG and Yb:YAG lasers. PMID:25402922

  12. Passively Q-switched and mode-locked dual-wavelength Nd:GGG laser with Cr4+:YAG as a saturable absorber

    NASA Astrophysics Data System (ADS)

    Chu, Hongwei; Zhao, Shengzhi; Li, Yufei; Yang, Kejian; Li, Guiqiu; Li, Dechun; Zhao, Jia; Qiao, Wenchao; Li, Tao; Feng, Chuansheng; Zhang, Haijuan

    2014-03-01

    By using neodymium-doped gadolinium gallium garnet (Nd:GGG) as a laser medium, a simultaneously passively Q-switched and mode-locked (QML) dual-wavelength laser with Cr4+:YAG as a saturable absorber is presented. The laser simultaneously oscillated at 1061 nm and 1063 nm, corresponding to a frequency difference of 0.53 THz. QML pulses with nearly 100% modulation depth were observed. The mode-locked pulse duration underneath the Q-switched envelope was estimated to be about 908 ps. The experimental results indicated that the dual-wavelength QML Nd:GGG laser can be an excellent candidate for the generation of THz waves.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Performance of efficient Q-switched diode-laser-pumped Nd:YAG and Ho:YLF lasers for space applications

    NASA Technical Reports Server (NTRS)

    Marshall, W. K.; Cowles, K.; Hemmati, H.

    1988-01-01

    Solid-state lasers pumped by continuous-wave diode lasers can be Q-switched to obtain high peak power output pulses. The dependence of laser-pulse energy, average output power, peak power, and pulse width on pulse-repetition frequency in Q-switched Nd:YAG and Ho:YLF lasers is determined and compared. At low pulse repetition rates, the much longer upper-stage lifetime in Ho:YLF gives a distinct advantage. At higher pulse rates, the overall laser efficiency and the stimulated emission cross section are more important parameters, leading to an advantage for Nd:YAG. The results are of significance for designing lasers for use in space optical communications and remote sensing systems.

  15. Passively Q-switched dual-wavelength Yb:LSO laser based on tungsten disulphide saturable absorber

    NASA Astrophysics Data System (ADS)

    Jing-Hui, Liu; Jin-Rong, Tian; He-Yang, Guoyu; Run-Qin, Xu; Ke-Xuan, Li; Yan-Rong, Song; Xin-Ping, Zhang; Liang-Bi, Su; Jun, Xu

    2016-03-01

    We demonstrate a passively Q-switched Yb:LSO laser based on tungsten disulphide (WS2) saturable absorber operating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 μs with a repetition rate of 76.9 kHz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 mW, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS2 nanoplatelets. Project supported by the National Scientific Research Project of China (Grant No. 61177047), Beijing Municipal Natural Science Foundation, China (Grant No. 1102005), and the Basic Research Foundation of Beijing University of Technology, China (Grant No. X3006111201501).

  16. A high-energy cladding-pumped 80 nanosecond Q-switched fiber laser using a tapered fiber saturable absorber

    NASA Astrophysics Data System (ADS)

    Moore, Sean W.; Soh, Daniel B. S.; Bisson, Scott E.; Patterson, Brian D.; Hsu, Wen L.

    2013-02-01

    We report a passively Q-switched all-fiber laser using a large mode area (LMA) Yb3+-doped fiber cladding-pumped at 915 nm and an unpumped single-mode Yb3+-doped fiber as the saturable absorber (SA). The saturable absorber and gain fibers were first coupled with a free-space telescope to better study the composite system, and then fusion spliced with fiber tapers to match the mode field diameters. ASE generated in the LMA gain fiber preferentially bleaches the SA fiber before depleting the gain, thereby causing the SA fiber to act as a passive saturable absorber. Using this scheme we first demonstrate a Q-switched oscillator with 40 μJ 79 ns pulses at 1026 nm using a free-space taper, and show that pulses can be generated from 1020 nm to 1040 nm. We scale the pulse energy to 0.40 mJ using an Yb3+-doped cladding pumped fiber amplifier. Experimental studies in which the saturable absorber length, pump times, and wavelengths are independently varied reveal the impact of these parameters on laser performance. Finally, we demonstrate 60 μJ 81 ns pulses at 1030 nm in an all fiber architecture using tapered mode field adaptors to match the mode filed diameters of the gain and SA fibers.

  17. LD-end-pumped passively Q-switched Nd:YAG ceramic laser with single wall carbon nanotube saturable absorber

    NASA Astrophysics Data System (ADS)

    Li, C. Y.; Bo, Y.; Zong, N.; Wang, Y. G.; Jiang, B. X.; Pan, Y. B.; Niu, G.; Fan, Z. W.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2012-10-01

    We report on a LD-end-pumped passively Q-switched Nd:YAG ceramic laser by using a novel single wall carbon nanotube saturable absorber (SWCNT-SA). The SWCNT wafer was fabricated by electric Arc discharge method on quartz substrate with absorption wavelength of 1064 nm. We firstly investigated the continuous wave (CW) laser performance and scattering properties of Nd:YAG ceramic sample. For the case of passively Q-switched operation, a maximum output power of 376 mW was obtained at an incident pump power of 8.68 W at 808 nm, corresponding to an optical-optical conversion efficiency of 4.3%. The repetition rate as the increase of pump power varied from 14 to 95 kHz. The minimum pulse duration of 1.2 μs and maximum pulse energy of 4.5 μJ was generated at a repetition rate of 31.8 kHz.

  18. Diverse output states from an all-normal dispersion ytterbium-doped fiber laser: Q-switch, dissipative soliton resonance, and noise-like pulse

    NASA Astrophysics Data System (ADS)

    Xu, Z. W.; Zhang, Z. X.

    2013-06-01

    An all-normal-dispersion ytterbium-doped fiber ring laser has been demonstrated, with different operation regimes: Q-switch, CW mode-locking and noise-like pulses, depending on the pump power and suitable orientation of the polarization controllers. As a transition between Q-switch and CW mode-locking, Q-switched mode-locking has also been observed. Moreover, our experiment shows that the CW mode-locking operation is the result of dissipative soliton resonance in the all-normal-dispersion fiber laser without external filter, which is a new way to generate high-energy pulses. This fiber laser with diverse outputs has many potential applications, and is helpful to investigate laser dynamics.

  19. High-pulse-energy passively Q-switched quasi-monolithic microchip lasers operating in the sub-100-ps pulse regime.

    PubMed

    Nodop, D; Limpert, J; Hohmuth, R; Richter, W; Guina, M; Tünnermann, A

    2007-08-01

    We present passively Q-switched microchip lasers with items bonded by spin-on-glass glue. Passive Q-switching is obtained by a semiconductor saturable absorber mirror. The laser medium is a Nd:YVO(4) crystal. These lasers generate pulse peak powers up to 20 kW at a pulse duration as short as 50 ps and pulse repetition rates of 166 kHz. At 1064 nm, a linear polarized transversal and longitudinal single-mode beam is emitted. To the best of our knowledge, these are the shortest pulses in the 1 microJ energy range ever obtained with passively Q-switched microchip lasers. The quasi-monolithic setup ensures stable and reliable performance. PMID:17671554

  20. BRIEF COMMUNICATIONS: Dye-jet laser pumped by the second harmonic of a Q-switched and mode-locked YAG:Nd3+ laser

    NASA Astrophysics Data System (ADS)

    Golubev, V. A.; Goncharov, A. N.; Maĭorov, A. P.; Makukha, V. K.; Smirnov, Vitalii A.; Tarasov, V. M.

    1981-05-01

    A report is given of the operating parameters of a dye jet laser pumped by the second harmonic of a cw Q-switched mode-locked YAG:Nd3+ laser. The dye laser emitted a continuous train of 250 nsec pulses at a repetition frequency of 25 kHz or a sequence of ultrashort pulse trains. A Lyot filter was used to tune the emission wavelength in the range 560-630 nm.

  1. Investigation of the laser pumping power impact on the operating regimes of a laser passively Q-switched by a saturated absorber

    NASA Astrophysics Data System (ADS)

    Benarab, Mustapha; Mokdad, Rabah; Djellout, Hocine; Benfdila, Arezki; Lamrous, Omar; Meyrueis, Patrick

    2011-09-01

    We have adapted the point model for the study of an all-fiber laser doped with Nd3+ and Q-switched by a saturable fiber absorber doped with Cr4+. Calculations of the output power of the 1084 nm laser are considered as a function of the pump power supplied by a 790 nm laser diode. The analysis of the simulation results reveals the existence of pulsed, sinusoidal, and dc operating regimes.

  2. Passively Q-switched 2 μm Tm:YAP laser based on graphene saturable absorber mirror.

    PubMed

    Hou, Jia; Zhang, Baitao; He, Jingliang; Wang, Zhaowei; Lou, Fei; Ning, Jian; Zhao, Ruwei; Su, Xiancui

    2014-08-01

    Using high-quality single-layer graphene as a saturable absorber, Tm:YAlO₃ (Tm:YAP) crystal as the gain medium, we demonstrated a laser-diode-pumped, compact, passively Q-switched (PQS) solid-state laser in the 2 μm region. The maximum average output power was 362 mW, with the corresponding largest pulse repetition rate and pulse energy of 42.4 kHz and 8.5 μJ, respectively. Under the same pump power, the pulse width of 735 ns was obtained, which is, to our best knowledge, the shortest pulse width among Tm-doped solid-state PQS lasers using graphene saturable absorber mirrors. PMID:25090328

  3. Passively Q-switched 1617-nm polycrystalline ceramic Er:YAG laser using a Cr:ZnSe saturable absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqi; Shen, Deyuan; Huang, Haitao; Liu, Jun; Zhang, Jian; Tang, Dingyuan; Fan, Dianyuan

    2015-08-01

    We report on a passively Q-switched polycrystalline ceramic Er:YAG laser by using a Cr:ZnSe crystal as a saturable absorber. When pumped by a 1532-nm Er-, Yb-doped fiber laser with the maximum power of 12.4 W, the laser yielded pulses of 28.8 ns duration at 1617 nm by using a saturable absorber with an initial transmission of 80 %. The corresponding peak power was up to 11.3 kW at a repetition rate of 2.17 kHz. The dependence of the pulse duration and repetition rate on the pump power was experimentally studied. The numerical and experimental results both show that the pulse duration was mainly determined by the initial transmission of the saturable absorber and slightly affected by the transmission of the output coupler. At last, we give some prospects for further narrowing down the pulse duration.

  4. CW and passively Q-switched laser performance of Nd:Lu2SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Di, Juqing; Zhang, Jian; Tang, Dingyuan; Xu, Jun

    2016-01-01

    We demonstrated an efficient and controllable dual-wavelength continuous-wave (CW) laser of Nd:Lu2SiO5 (Nd:LSO) crystal. The maximum output power was 3.02 W at wavelength of 1075 nm and 1079 nm, and with increasing of absorbed pump power, the ratio of 1079 nm laser rose. The slope efficiency of 65.6% and optical-to-optical conversion efficiency of 63.3% were obtained. The passively Q-switched laser properties of Nd:LSO were investigated for the first time. The shortest pulse, maximum pulse energy and peak power were 11.58 ns, 29.05 μJ and 2.34 kW, respectively.

  5. Q-switched waveguide laser based on two-dimensional semiconducting materials: tungsten disulfide and black phosphorous.

    PubMed

    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. PMID:26906854

  6. WS2 as a saturable absorber for Q-switched 2  micron lasers.

    PubMed

    Luan, Chao; Yang, Kejian; Zhao, Jia; Zhao, Shengzhi; Song, Lei; Li, Tao; Chu, Hongwei; Qiao, Junpeng; Wang, Chao; Li, Zhen; Jiang, Shouzhen; Man, Baoyuan; Zheng, Lihe

    2016-08-15

    We prepared WS2 nanosheets by using the thermal decomposition method and demonstrated for the first time its nonlinear saturable absorption property at around 2 μm. With the as-prepared WS2 nanosheets as saturable absorber (SA), a passively Q-switched Tm:LuAG laser was realized successfully, and 660 ns laser pulses with an average output power of 1.08 W and pulse peak power of 26 W at a repetition rate of 63 kHz were obtained for an incident pump power of 7 W. Our experimental results definitely demonstrate that WS2 could be a kind of promising SA for solid-state 2 μm lasers. PMID:27519088

  7. 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.

    PubMed

    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). There was no statistically significant difference between the two sides (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. PMID:25968166

  8. A Q-switched multi-wavelength Brillouin erbium fiber laser with a single-walled carbon nanotube saturable absorber

    NASA Astrophysics Data System (ADS)

    Tan, S. J.; Harun, S. W.; Ahmad, F.; Nor, R. M.; Zulkepely, N. R.; Ahmad, H.

    2013-05-01

    A Q-switched multi-wavelength Brillouin erbium fiber laser (MWBEFL) is demonstrated using a single-walled carbon nanotube-polyethylene oxide (SWCNT-PEO) saturable absorber (SA). The SA is fabricated by cutting off a small part of the developed SWCNT-PEO film and sandwiching it in between two FC/PC (fiber connector/physical contact) fiber connectors. Multi-wavelength combs with ten lasing lines and spacing of 0.158 nm are obtained by the use of 2 km long dispersion compensating fiber as the Brillouin gain medium and a four-port circulator to isolate and circulate the odd-order Stokes signals. Q-switched pulse trains with a repetition rate of 105.2 kHz and a pulse width of 0.996 μs are obtained in the proposed MWBEFL at a 1480 nm pump power of 120 mW and a Brillouin pump power of 5.4 dBm.

  9. Nanosecond pulse generation in a passively Q-switched Nd:GGG laser at 1331 nm by CVD graphene saturable absorber

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Wang, Yi; Cheng, Yongjie; Yang, Han; Xu, Huiying; Cai, Zhiping

    2015-10-01

    We report on a nanosecond pulse generation in a diode end-pumped passively Q-switched Nd:GGG laser at the low-gain transition line of 1331 nm. A three-layer CVD graphene thin film was transferred from Cu foil to a BK7 glass substrate for the use of saturable absorber. A stable Q-switching laser operation was obtained with maximum average output power of 0.69 W and slope efficiency of about 11.0% with respect to the absorbed pump power. The shortest pulse duration and the maximum repetition rate of the pulse trains were registered to be 556 ns and 166.7 kHz with corresponding maximum pulse energy 4.14 μJ and pulse peak power 7.45 W. This is the first demonstration of CVD-graphene-based Q-switched laser operation at 1.3 μm, to the best of our knowledge.

  10. Narrow-band 1 W source at 257 nm using frequency quadrupled passively Q-switched Yb:YAG laser.

    PubMed

    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. PMID:27464186

  11. Evaluation of a commercially available passively Q-switched Nd:YAG laser with LiF: F2- saturable absorber for laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Carson, Cantwell G.; Goueguel, Christian L.; Sanghapi, Hervé; Jain, Jinesh; McIntyre, Dustin

    2016-05-01

    Interest in passively Q-switched microchip lasers as a means for miniaturization of laser-induced breakdown spectroscopy (LIBS) apparatus has rapidly grown in the last years. To explore the possibility of using a comparatively UV-vis transparent absorber, we herein present the first report on the evaluation of a commercially available flash lamp-pumped passively Q-switched Nd:YAG laser with LiF: F2- saturable absorber as an excitation source in LIBS. Quantitative measurements of barium, strontium, rubidium and lithium in granite, rhyolite, basalt and syenite whole-rock glass samples were performed. Using a gated intensified benchtop spectrometer, limits of detection of 0.97, 23, 37, and 144 ppm were obtained for Li, Sr, Rb, and Ba, respectively. Finally, we discuss the advantages of using such a laser unit for LIBS applications in terms of ablation efficiency, analytical performances, output energy, and standoff capabilities.

  12. The pulsed dye laser versus the Q-switched Nd:YAG laser in laser-induced shock-wave lithotripsy.

    PubMed

    Thomas, S; Pensel, J; Engelhardt, R; Meyer, W; Hofstetter, A G

    1988-01-01

    To date, there are two fairly well-established alternatives for laser-induced shock-wave lithotripsy in clinical practice. The Q-switched Nd:YAG laser is distinguished by the high-stone selectivity of its coupler systems. The necessity of a coupler system and its fairly small conversion rate of light energy into mechanical energy present serious drawbacks. Furthermore, the minimal outer diameter of the transmission system is 1.8 mm. The pulsed-dye laser can be used with a highly flexible and uncomplicated 200-micron fiber. However, the laser system itself is more complicated than the Q-switched Nd:YAG laser and requires a great deal of maintenance. Biological evaluation of damage caused by direct irradiation shows that both laser systems produce minor damage of different degrees. YAG laser lithotripsy with the optomechanical coupler was assessed in 31 patients with ureteral calculi. The instability and limited effectiveness of the fiber application system necessitated auxiliary lithotripsy methods in 14 cases. Dye-laser lithotripsy is currently being tested in clinical application. Further development, such as systems for blind application or electronic feedback mechanisms to limit adverse tissue effects, have yet to be optimized. Nevertheless, laser-induced shock-wave lithotripsy has the potential to become a standard procedure in the endourologic management of stone disease. PMID:2902500

  13. Passive q-switching of CO/sub 2/ TEA laser using sulfur hexafluoride (SF/sub 6/). Report for April-August 1986

    SciTech Connect

    Pastel, R.

    1986-10-01

    Passive Q-switching of a CO/sub 2/ TEA laser using sulfur hexafluoride (SF/sub 6/) was demonstrated at 10.2 micron. There is minimum loss of peak power, narrowing of the pulse, and elimination of the tail. Q-switching at 9.6 micron was not observed. Also discussed is the use of SF/sub 6/ to frequency the laser to the strong gain lines of the 10.2-m and 9.6-m branch of the CO/sub 2/ emission. Both theory and experimental results are given.

  14. Diode-pumped CW and passively Q-switched lasers of Nd:GdLuAG mixed garnet at 1123 nm

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Liu, Zhaojun; Zhang, Sasa; Xia, Jinbao; Zhang, Yanmin; Guan, Chen

    2016-03-01

    Diode-pumped CW and passively Q-switched lasers of Nd:GdLuAG mixed garnet at 1123 nm were demonstrated. The maximum average output power of CW operation was 4.13 W. For Q-switched operation, the average output power was 800 mW, the corresponding single pulse energy was 133.8 μJ. The Nd:GdLuAG laser emitting at 1123 nm was obtained for the first time to the best of our knowledge, which proves that the Nd:GdLuAG mixed garnet has a better ability of energy storage than Nd:YAG in 1123 nm oscillation.

  15. Gold nanobipyramids as saturable absorbers for passively Q-switched laser generation in the 1.1  μm region.

    PubMed

    Zhang, Huanian; Liu, Jie

    2016-03-15

    We demonstrated that gold nanobipyramids (Au-NBPs) can be used as saturable absorbers for ultrafast pulsed-laser application, for the first time. Au-NBPs are prepared through a seed-mediated growth method, and performance is investigated in a passively Q-switched Nd:YVO4 laser. In the Q-switched operation the maximum average output power that can be achieved is 151 mW. The minimum pulse width is 396 ns at a pulse repetition rate of 90.6 kHz. PMID:26977656

  16. MoS2 nanoflowers as high performance saturable absorbers for an all-fiber passively Q-switched erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    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

  17. Compact self-Q-switched green upconversion Er:ZBLAN all-fiber laser operating at 543.4  nm.

    PubMed

    Luo, Zhengqian; Ruan, Qiujun; Zhong, Min; Cheng, Yongjie; Yang, Runhua; Xu, Bin; Xu, Huiying; Cai, Zhiping

    2016-05-15

    We report the demonstration of a compact self-Q-switched green upconversion Er3+:ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber laser operating at 543.4 nm. The all-fiber green laser simply consists of a 45 cm high-concentration Er3+:ZBLAN fiber, a 976 nm pump source, and a pair of fiber end-facet mirrors. Under the strong excitation of the 976 nm pump laser, green upconversion lasing at 543.4 nm is achieved from the compact Er3+:ZBLAN fiber laser. Interestingly, the green laser exhibits stable self-Q-switching operation. As the 976 nm pump power is increased, the pulse repetition rate linearly increases from 25.9 to 50.8 kHz and the pulse width narrows from 7.2 to 1.95 μs. The Q-switched green laser has a pump threshold of 118 mW and a maximum output power of 6.9 mW with a slope efficiency of 30%. This is, to the best of our knowledge, the shortest-wavelength operation of a self-started or passively Q-switched fiber laser. PMID:27176977

  18. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    SciTech Connect

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-05

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm{sup −2}.

  19. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-01

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm-2.

  20. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser

    PubMed Central

    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

  1. Severe unexpected adverse effects after permanent eye makeup and their management by Q-switched Nd:YAG laser.

    PubMed

    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

  2. Facial scars after a road accident: combined treatment with PDL and Q-switched ND:YAG laser.

    PubMed

    Martins, Andrea; Trindade, Felicidade; Leite, Luiz

    2008-09-01

    We report the case of a woman who presented with several facial scars following a road accident. Treatment was carried out using combined laser treatment with pulsed dye laser (PDL) and the Q-switched neodymium:yttrium-aluminum-garnet laser (QS Nd:YAG laser). No side effects or complications from treatment were noted or reported. The patient had very good cosmetic results with this combined technique. A variety of facial scars--erythematous, pigmented, atrophic and hypertrophic--may occur as a result of trauma, surgery, burns and skin disease. Surgery with other adjunctive methods including radiotherapy, intralesional steroids and pressure therapy has shown variable results. Laser treatment has been attempted for scar revision since the 1980s. The PDL is the optimal treatment for reducing scar bulk and symptoms. It also decreases the erythema and telangiectasia associated with scars, normalizes the skin surface texture and improves scar pliability. The QS Nd:YAG laser (1064 nm) is highly effective for traumatic tattoo removal, resulting in complete clearance in the majority of cases. PMID:18608707

  3. 2.79 μm high peak power LGS electro-optically Q-switched Cr,Er:YSGG laser.

    PubMed

    Wang, Li; Wang, Jintao; Yang, Jingwei; Wu, Xianyou; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe; Wang, Jiyang; Xu, Changqing

    2013-06-15

    A flash lamp pumped Cr,Er:YSGG laser utilizing a langasite (LGS) crystal as an electro-optic Q-switch is proposed and demonstrated. It is proved that a LGS crystal with relatively high damage threshold can be used as the electro-optic Q-switch at 2.79 μm, and 216 mJ pulse energy with 14.36 ns pulse width is achieved. Its corresponding peak power of pulse can reach 15 MW, to our knowledge the best result at a 2.79 μm wavelength. PMID:23939006

  4. Tunable Q-switched fiber laser based on saturable edge-state absorption in few-layer molybdenum disulfide (MoS₂).

    PubMed

    Woodward, R I; Kelleher, E J R; Howe, R C T; Hu, G; Torrisi, F; Hasan, T; Popov, S V; Taylor, J R

    2014-12-15

    We fabricate a few-layer molybdenum disulfide (MoS₂) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from 1030 to 1070 nm. Self-starting Q-switching generates 2.88 μs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS₂ sample, despite operating at photon energies lower than the material bandgap. PMID:25607060

  5. LD-pumped passively Q-switched Nd:GGG laser at 1062 nm with a GaAs saturable absorber

    NASA Astrophysics Data System (ADS)

    Zhang, H. N.; Li, P.; Wang, Q. P.; Chen, X. H.

    2011-11-01

    we have experimentally studied the passively Q-switched performance of a diode-pumped Nd:GGG laser at 1062 nm with a GaAs saturable absorber, in the experiment when the pumped power was 9.8 W, the maximum CW output power of 5.1 W was obtained. The optical conversion efficiency and the slop efficiency were 52 and 53%, respectively. The threshold was 0.9 W. In the passively Q-switched regime, we get the average output power of 0.93 W. The shortest pulse width and pulse repetition rate were 7 ns and 188 kHz, respectively.

  6. Broadband tuning in a passively Q-switched erbium doped fiber laser (EDFL) via multiwall carbon nanotubes/polyvinyl alcohol (MWCNT/PVA) saturable absorber

    NASA Astrophysics Data System (ADS)

    Ahmad, H.; Hassan, S. N. M.; Ahmad, F.; Zulkifli, M. Z.; Harun, S. W.

    2016-04-01

    An MWCNT/PVA-based Q-switched erbium-doped fiber laser (EDFL) that uses a tunable bandpass filter (TBPF) as the wavelength tuning and filtering mechanism to achieve a broadband tuning range is proposed and demonstrated. The tuning range of the generated Q-switched pulses covered a wide wavelength range of 50 nm, which spanned from 1519 nm to 1569 nm and corresponded to the S- and C-band regions. In addition, the lasing and Q-switching operations had low thresholds of 8.9 mW and 22.4 mW respectively. The highest pulse energy of 52.13 nJ was obtained at an output wavelength of 1569 nm, with a corresponding repetition rate of 26.53 kHz and pulse width of 6.10 μs, at the maximum power of 114.8 mW.

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

    PubMed Central

    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

  8. Efficient passive Q-switching operation of a diode-pumped Nd:GdVO4 laser with a Cr4+:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    Liu, Junhai; Ozygus, Bernd; Yang, Suhui; Erhard, Jürgen; Seelig, Ute; Ding, Adalbert; Weber, Horst; Meng, Xianlin; Zhu, Li; Qin, Lianjie; Du, Chenlin; Xu, Xinguang; Shao, Zongshu

    2003-04-01

    A diode-pumped highly efficient Cr4+:YAG passively Q-switched Nd:GdVO4 laser formed by a plano-concave resonator has been demonstrated. At the highest attainable absorbed pump power of 11.4 W, 4.05 W of average output power, which was two thirds of the maximum corresponding cw output, was achieved with an optical conversion efficiency of 35.5%, and the slope efficiency was determined to be 46.8%, reaching 85% of the magnitude of its cw counterpart. The resulting shortest pulse duration, single-pulse energy, and peak power were found to be 13 ns, 90 μJ, and 7 kW, respectively, with a pulse repetition frequency (PRF) of 45 kHz. Two particularly modified resonator configurations were employed; the largest pulse energy and the highest peak power reached were, respectively, 154 μJ and 11.2 kW at 8.5 W of absorbed pump power. An analytical relation between the PRF and the absorbed pump power is given for a passively Q-switched laser, showing good consistency with experiment with a Nd:GdVO4 laser. The dependence of the operational parameters on the pump power and on the output coupling was also investigated experimentally. Issues involving the criterion for passive Q switching are discussed in some detail for Cr4+:YAG passively Q-switched neodymium-doped vanadate lasers.

  9. MoS2 nanoflowers as high performance saturable absorbers for an all-fiber passively Q-switched erbium-doped fiber laser.

    PubMed

    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. PMID:26997036

  10. High-speed cutting of thin materials with a Q-switched laser in a water-jet versus conventional laser cutting with a free running laser

    NASA Astrophysics Data System (ADS)

    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.

  11. Experimental retinectomy with a 6.1 μm Q-switched Raman-shifted alexandrite laser

    NASA Astrophysics Data System (ADS)

    Joos, Karen M.; Prasad, Ratna; Kozub, John; Ivanov, Borislav; Agarwal, Anita; Shen, Jin H.

    2010-02-01

    Purpose: It is hypothesized that 6.1 μm produced by a portable laser would be useful for incising tissue layers such as performing a retinectomy in detached retina with extensive anterior proliferative vitreoretinopathy. Methods: An alexandrite laser system, which provides a high-intensity Q-switched pulse (780 nm, 50-100 ns duration, 10 Hz), is wavelength-shifted by a two-stage stimulated Raman conversion process into the 6-7 μm range (Light Age, Inc.). Fresh cadaver porcine retinas were lased with 6.1 μm using a 200 μm diameter spot at 0.6 mJ after removal of the vitreous. Specimens were examined grossly and prepared for histological examination. Results: The Raman-shifted alexandrite laser produced a smooth Gaussian profile. A narrow spectrum was produced at 6.1 μm. A full-thickness retinal incision with minimal thermal damage was obtained at a low energy level of 0.6 mJ in the retinas. However, the depth of the incision did vary from an incomplete incision to a full-thickness incision involving the underlying choroidal layer in attached retinas. Conclusions: The 6.1 μm mid-infrared energy produced by a portable laser is capable of incising detached retinas with minimal thermal damage.

  12. Quasi-CW diode-pumped self-starting adaptive laser with self-Q-switched output.

    PubMed

    Smith, G; Damzen, M J

    2007-05-14

    An investigation is made into a quasi-CW (QCW) diode-pumped holographic adaptive laser utilising an ultra high gain (approximately 10(4)) Nd:YVO(4) bounce amplifier. The laser produces pulses at 1064 nm with energy approximately 0.6 mJ, duration <3 ns and peak power approximately 200 kW, with high stability, via self-Q-switching effects due to the transient dynamics of the writing and replay of the gain hologram for each pump pulse. The system produces a near-diffraction-limited output with M(2)<1.3 and operates with a single longitudinal mode. In a further adaptive laser configuration, the output was amplified to obtain pulses of approximately 5.6 mJ energy, approximately 7 ns duration and approximately 1 MW peak power. The output spatial quality is also M(2)<1.3 with SLM operation. Up to 2.9 mJ pulse energy of frequency doubled green (532 nm) radiation is obtained, using an LBO crystal, representing approximately 61% conversion efficiency. This work shows that QCW diode-pumped self-adaptive holographic lasers can provide a useful source of high peak power, short duration pulses with excellent spatial quality and narrow linewidth spectrum. PMID:19546951

  13. Modeling of beam width in passively Q-switched end-pumped lasers.

    PubMed

    Jabczyński, Jan; Kwiatkowski, Jacek; Zendzian, Waldemar

    2003-03-24

    An iterative model based on the LambertW function was developed for estimating the fundamental mode parameters of resonators with saturable gain guiding. The process of pulse buildup in passively Qswitched, end-pumped lasers was analyzed. The effective ABCD cavity matrix for consecutive round-trips was calculated, taking into account spatially variable saturated gain in an active medium and absorption bleaching in a saturable absorber. The twofold decrease in beam width, as compared with the fundamental mode of the bare cavity, was demonstrated. The application of such a model for resonators with other nonlinear elements is feasible. PMID:19461764

  14. Treatment of enlarged pores with the quasi long-pulsed versus Q-switched 1064 nm Nd:YAG lasers: A split-face, comparative, controlled study

    PubMed Central

    Roh, MR; Goo, BC; Jung, JY; Chung, HJ; Chung, KY

    2011-01-01

    Background and Aims: A variety of treatment modalities have been used to reduce the size of en-larged pores. The 1064 nm Nd:YAG laser, in addition to its role in removal of tattoos and age-related dyschromia, depilation and skin rejuvenation, may also play a role in reducing the size of enlarged pores. The present split-face controlled study assessed and compared the efficacy between the quasi long-pulsed (micropulsed) and the Q-switched modes of the Nd:YAG laser in the treatment of enlarged pores. Subjects and Methods: Twenty subjects with enlarged pores were recruited for the micropulsed vs Q-switched study, all treated with the same 1064 nm Nd:YAG laser system. Ten subjects were treated with the 300 µs micropulsed mode and the other ten subjects were treated with the 5 ns Q-switched mode. All subjects were treated on the right half of the face, the left half serving as an untreated control. Five laser sessions were performed. The pore sizes were measured using an image analysis program and the sebum level was measured with a Sebumeter® before and after the treatments. Results: The pore size and sebum level significantly decreased with treatment on the treated side (right cheek and right half of nose) in both the micropulsed and Q-switched modes compared to the control side (p<0.05), but without any statistically significant difference between the modes. Conclusions: The micropulsed and Q-switched Nd:YAG laser treatments reduced pore size and sebum levels with more or less equal efficacy and with no adverse side effects. PMID:24155526

  15. Single-frequency, injection-seeded Q-switched operation of resonantly pumped Er:YAG ceramic laser at 1645 nm

    NASA Astrophysics Data System (ADS)

    Ye, Qing; Gao, Chunqing; Wang, Shuo; Na, Quanxin; Shi, Yang; Wang, Qing; Gao, Mingwei; Zhang, Jian

    2016-07-01

    A single-frequency Q-switched Er:YAG polycrystalline ceramic laser is reported for the first time. The `Ramp-Hold-Fire' injection-seeding technique was employed to obtain single-frequency pulses, with an Er:YAG NPRO as a seed laser. Single-frequency laser operation was obtained with pulse energy of 4.7 mJ, pulse width of 250 ns and pulse repetition rate of 200 Hz.

  16. Nanosecond pulse passively Q-switched Yb-doped fiber laser with Cr4+: YAG as saturable absorber

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Liu, Jiang; Wang, Pu

    2011-06-01

    We report a passively Q-switched Yb-doped fiber laser with Cr4+:YAG saturable absorber and get stable nanosecond pulse trains. Three kinds of laser cavity configurations, including a cladding-pumped ring cavity, a cladding-pumped linear cavity and a core-pumped linear cavity were studied, and they all can effectively restrain the generation of Stimulated Brillouin scattering and the generation of self-pulse. Cladding-pumped ring-avity fiber laser with Cr4+:YAG as saturable absorber inside is established for the first time to obtain stable 1 μs pulse trains. The amplitude fluctuation and timing jitter are below 5% (rms). Further more, we can also get stable pulse trains by using a high reflective fiber Bragging grating as a resonator mirror in a cladding-pumped linear cavity and a core-pumped linear cavity fiber laser respectively. In the cladding-pumped linear cavity fiber laser, the tunable pulse repetition rate is from 9.1 kHz to 30.3 kHz and the minimum pulse duration is 156 ns. And in the core-pumped linear cavity fiber laser, the tunable pulse repetition rate is from 15 kHz to 33 kHz and the minimum pulse duration is 24 ns which much less than those reported before. Although the average output power is only hundreds milli-Watts now, the laser uses a fiber coupler as the output of pulse trains, it is convinient to boost the power with a stage of fiber amplifier. This kind of pulse laser can be used as a seed source, and amplified to tens of Watts for practical applications in the future.

  17. Low-pulse energy Q-switched Nd:YAG laser treatment for hair-dye-induced Riehl's melanosis.

    PubMed

    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. PMID:25602355

  18. Bundled hollow optical fibers for transmission of high-peak-power Q-switched Nd:YAG laser pulses

    NASA Astrophysics Data System (ADS)

    Yilmaz, Ozgur; Miyagi, Mitsunobu; Matsuura, Yuji

    2006-09-01

    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.

  19. Lean-Burn Stationary Natural Gas Reciprocating Engine Operation with a Prototype Miniature Diode Side Pumped Passively Q-switched Laser Spark Plug

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    Lasing in Nd:NaLa(MoO4)2 crystals is obtained without stabilisation of the diode pump wavelength. A dependence of the cw laser power (at a wavelength of 1059 nm) on the pump diode temperature is found within a range of 10—458C. It is shown that the variations in the diode temperature within this region change the lasing efficiency no more than by 30%. In the passive Q-switching regime, the experiments were performed under both pulsed and cw pumping. Upon pulsed pumping, the laser energy was 16 μJ at the output pulse duration of 11 ns. The laser wavelength was 1059 nm, as well as in the case of cw operation. Upon cw pumping with a power of 1.5 W, laser pulses were obtained with an energy of 15 μJ.

  1. Removal of graffiti from the mortar by using Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Sanjeevan, Poologanathan; Klemm, Agnieszka J.; Klemm, Piotr

    2007-08-01

    This paper presents part of the larger study on microstructural features of mortars and it's effects on laser cleaning process. It focuses on the influence of surface roughness, porosity and moisture content of mortars on the removal of graffiti by Nd:YAG laser. The properties of this laser are as follows: wavelength ( λ) 1.06 μm, energy: 500 mJ per pulse, pulse duration: 10 ns. The investigation shows that the variation of laser fluence with the number of pulses required for the laser cleaning can be divided into two zones, namely effective zone and ineffective zone. There is a linear relationship observed between number of pulses required for laser cleaning and the laser fluence in the effective zone, while the number of pulses required for the laser cleaning is almost constant even though the laser fluence increases in the ineffective zone. Moreover, surface roughness, porosity and moisture content of mortar samples have influence on the laser cleaning process. The effect of these parameters become however negligible at the high level of laser fluence. The number of pulses required for the laser cleaning is low for smooth surface or less porous mortar. Furthermore, the wetness of the samples facilitates the cleaning process.

  2. Generation of more than 40  W of average output power from a passively Q-switched Yb-doped fiber laser.

    PubMed

    Chakravarty, Usha; Kuruvilla, Antony; Singh, Ravindra; Upadhyaya, B N; Bindra, K S; Oak, S M

    2016-01-10

    We report on the generation of 41.6 W of average output power from a passively Q-switched ytterbium-doped fiber laser using Cr4+:YAG crystal as a saturable absorber (SA). This is the highest average power from passively Q-switched fiber lasers reported so far in the literature, to our knowledge, and it has been achieved by using a specially designed T-type double-end pumping configuration. Variation in average output power, pulse energy, pulse duration, pulse frequency, and pulse-to-pulse stability has also been studied using SAs of different linear transmissions. The effect of an intracavity SA on self-pulsing dynamics was also investigated and it was observed that, at lower input pump power near threshold, the presence of an SA enhances the peak power of relaxation oscillations to trigger the generation of stimulated Raman scattering in the gain fiber. With an increase in pump power, when the passive Q-switching threshold is reached, high peak power random self-pulses regenerate into low amplitude regular Q-switched pulses. The effect of the length of the gain medium on dual-wavelength generation at very low input pump power and broadband generation at sufficiently higher pump power has also been explored. PMID:26835764

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    1987-12-01

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

  5. Dynamic photopatterning of cells in situ by Q-switched neodymium-doped yttrium ortho-vanadate laser

    NASA Astrophysics Data System (ADS)

    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.

  6. Bi2Te3 based passively Q-switched fiber laser with cylindrical vector beam emission.

    PubMed

    Yan, Ke; Lin, Jian; Zhou, Yong; Gu, Chun; Xu, Lixin; Wang, Anting; Yao, Peijun; Zhan, Qiwen

    2016-04-10

    We report a passively Q-switched fiber laser with cylindrical vector beam output modes using a few-mode fiber Bragg grating as a polarization-selective output coupler and Bi2Te3 as the saturable absorber. Both radially and azimuthally polarized beams can be readily generated, and the output polarization can be switchable by tuning the polarization controllers inside the laser cavity. The repetition rate of the Q-switched laser can be tuned from 31.54 to 49.40 kHz when the pump power increases from 103.5 to 139.5 mW. The fiber laser operates at a single wavelength of 1557.5 nm with a 3 dB linewidth of <0.04  nm. PMID:27139870

  7. Bindi Tattoo on Forehead: Success with Modified R-20 Technique Using Low Fluence Q-Switched Nd Yag Laser: A Case Report

    PubMed Central

    Zawar, Vijay; Sarda, Aarti; De, Abhishek

    2014-01-01

    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. PMID:24761103

  8. Treatment of high myopia using a passively Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Dabu, Razvan V.; Carstocea, Benone D.; Burcea, M.

    1992-08-01

    A method of lens extraction after Nd:YAG laser capsulonucleolysis in the eyes with high myopia is described. The scheme and performance specifications of the Nd:YAG laser used for preparing the extracapsular lens extraction are presented. The treatment begins a few months before lens extraction by scleroplasty associated with cryoprofilaxy or Argon laser endocerclage. Twenty-four to forty-eight hours before the operation Nd:YAG laser pulses are applied on the exterior capsule, first in the periphery and then just in the middle of the pupila. A capsulonucleolysis is obtained and the extraction of the transparent lens is performed in extracapsular extraction of the cataract.

  9. 1064 nm Q-switched Nd:YAG laser for the treatment of Argyria: a systematic review.

    PubMed

    Griffith, R D; Simmons, B J; Bray, F N; Falto-Aizpurua, L A; Yazdani Abyaneh, M-A; Nouri, K

    2015-11-01

    Argyria is a benign skin disease characterized by blue to slate-grey discoloration that is caused by deposition of silver granules in the skin and/or mucus membranes as a result of long-term ingestion of ionized silver solutions or exposure to airborne silver particles. The skin discoloration can be generalized or localized and is exacerbated by sunlight. The skin discoloration is usually permanent, and until recently, there has been no effective treatment for argyria. Over the past 6 years, a number of case reports and one case series have described cases of argyria that were successfully treated with a 1064 nm Q-switched (QS) neodymium-doped yttrium aluminium garnet (Nd:YAG) laser; however, a review of these studies has never been reported in the dermatologic literature. To review the use of the 1064 nm QS Nd:YAG laser for the treatment of argyria. A search of the National Library of Medicine's PubMed Database and the SCOPUS Database was performed to find articles that detailed the treatment of argyria with 1064 nm QS Nd:YAG laser. Six articles were selected for inclusion in this review. Each article was reviewed and summarized in a table. A 1064 nm QS Nd:YAG laser offers a novel and effective treatment for argyria. A systematic review of the dermatologic literature revealed a limited number of case reports and case series using this treatment. However, the results gleaned by the authors from the literature review provide important information to the clinician. For patients with argyria, a single pass of the 1064 nm QS Nd:YAG laser offers immediate, effective and sustained pigment clearing without any long-term adverse effects. PMID:25845405

  10. Optical parameteric oscillation in MgO:LiNbO sub 3 driven by a diode pumped single frequencey q-switched laser

    SciTech Connect

    Gerstenberger, D.C.; Tye, G.E.; Wallace, R.W. )

    1990-01-01

    The authors report how they have obtained optical parametric oscillation tunable over the 940--1220 nm spectral region from a monolithic magnesium oxide doped lithium niobate ring resonator. The monolithic OPO was pumped by the 532 nm second harmonic of a diode laser pumped single frequency {ital Q}-switched Nd:YAG laser. The exceptional frequency and amplitude stability of the single frequency pump source provided stable OPO output pulses.

  11. High-power high-efficiency acousto-optically Q-switched rod Nd:YAG laser with 885 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Liu, K.; Li, F. Q.; Xu, H. Y.; Wang, Z. C.; Zong, N.; Du, S. F.; Bo, Y.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2013-01-01

    We have demonstrated a compact Q-switched Nd:YAG laser at 1064 nm with 885 nm diode-laser (LD) direct pumping. At a repetition rate of 100 kHz, an average output power of 53 W with beam quality factor M2 of 1.6 was achieved under the absorbed pump power of 122 W, corresponding to an optical-optical efficiency of 43.5% and a slope efficiency of 57.6%, respectively. The pulse width and the peak power at this output power were 112 ns and 4.74 kW, respectively.

  12. An optimized fiber delivery system for Q-switched, Nd:YAG lasers

    SciTech Connect

    Setchell, R.E.

    1996-11-01

    Interest in the transmission of high intensities through optical fibers is being motivated by an increasing number of applications. Using different laser types and fiber materials, various studies are encountering transmission limitations due to laser-induced damage processes. The authors have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. System attributes that will affect breakdown and damage thresholds include laser characteristics, the design and alignment of laser-to-fiber injection optics, and fiber end-face preparation. In the present work the authors have combined insights gained in past studies in order to establish what thresholds can be achieved if all system attributes can be optimized to some degree. The multimode laser utilized past modifications that produced a relatively smooth, quasi-Gaussian profile. The laser-to-fiber injection system achieved a relatively low value for the ratio of peak-to-average fluences at the fiber entrance face, incorporated a mode scrambler to generate a broad mode power distribution within the initial segment of the fiber path, and had improved fixturing to insure that the fiber axis was collinear with the incident laser beam. Fiber end faces were prepared by a careful mechanical polishing schedule followed by surface conditioning using a CO{sub 2} laser. In combination, these factors resulted in higher thresholds for breakdown and damage than they had achieved previously in studies that utilized a simple lens injection system.

  13. Treatment of Melasma with the Photoacoustic Twin Pulse Mode of Low-Fluence 1,064 nm Q-Switched Nd:YAG Laser

    PubMed Central

    Kim, Jee Young; Choi, Misoo; Nam, Chan Hee; Kim, Ji Seok; Kim, Myung Hwa; Park, Byung Cheol

    2016-01-01

    Background Low-fluence 1,064 nm Q-switched Nd:YAG laser has been widely used for the treatment of melasma. Although new Q-switched Nd:YAG lasers with photoacoustic twin pulse (PTP) mode have been recently developed for high-efficiency, there is limited information available for the new technique. Objective This study was designed to investigate the efficacy and adverse effects after few sessions of repeated low fluence 1,064 nm Q-switched Nd:YAG laser treatment with PTP mode in Asian women with melasma. Methods Twenty-two Korean women were treated with a total of five sessions of low-fluence PTP mode Nd:YAG laser treatment (Pastelle®) at 2 weeks interval. Responses to treatments were evaluated by using Melasma Area and Severity Index (MASI) scoring, colorimeter measurement, and the investigators' and patients' overall assessments. Adverse events were recorded at each visit. Results Investigators' and patients' overall assessment showed that 'significantly improved' was assessed by 13 (59.1%) and 19 of 22 patients (86.4%), respectively. MASI scores were significantly reduced by 20.4%. The lightness, measured by using a colorimeter, was significantly increased by 1.3 point. Notable adverse events were not observed. Conclusion After 5 sessions of laser therapy alone, about 60% of the subjects showed significant improvement. Few sessions of repeated laser toning treatment using the PTP mode is a safe and effective way to treat facial melasma. PMID:27274626

  14. Compact diode-pumped continuous-wave and passively Q-switched Nd:GYSO laser at 1.07 μm

    NASA Astrophysics Data System (ADS)

    Lin, Zhi; Huang, Xiaoxu; Lan, Jinglong; Cui, Shengwei; Wang, Yi; Xu, Bin; Luo, Zhengqian; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Xiaoyan; Wang, Jun; Xu, Jun

    2016-08-01

    We report diode-pumped continuous-wave (CW) and Q-switched Nd:GYSO lasers using a compact two-mirror linear laser cavity. Single-wavelength laser emissions at 1074.11 nm with 4.1-W power and at 1058.27 nm with 1.47-W power have been obtained in CW mode. The slope efficiencies with respect to the absorbed pump powers are 48.5% and 22.9%, respectively. Wavelength tunability is also demonstrated with range of about 8 nm. Using a MoS2 saturable absorber, maximum average output power up to 410 mW at 1074 nm can be yielded with absorbed pump power 6.41 W and the maximum pulse energy reaches 1.20 μJ with pulse repetition rate of 342.5 kHz and shortest pulse width of 810 ns. The CW laser results represent the best laser performance and the Q-switching also present the highest output power for Q-switched Nd3+ lasers with MoS2 as saturable absorber.

  15. Influence of focal point properties on energy transfer and plasma evolution during laser ignition process with a passively q-switched laser.

    PubMed

    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. PMID:27410797

  16. Use of the Q-switch Nd:YAG laser in the treatment of cataracts

    NASA Astrophysics Data System (ADS)

    Kecik, Dariusz

    1997-10-01

    The most frequent uses of the Nd:YAG laser in the surgical treatment for cataract are presented. Preoperative, intraoperative and postoperative applications are discussed together with the most frequency complications.

  17. Tattoo ink darkening of a yellow tattoo after Q-switched laser treatment.

    PubMed

    Varma, S; Swanson, N A; Lee, K K

    2002-09-01

    The popularity of tattoos is burgeoning with 20-30 million tattooed individuals in the Western World. Requests for removal can be expected to rise concurrently with increased applications. Laser removal of tattoos is potentially a more cosmetically acceptable method of removing tattoos than surgical excision or dermabrasion. Nevertheless, complications and side-effects can result from laser treatment and include scarring, hypopigmentation, hyperpigmentation, partial removal, infection, bleeding and tattoo ink darkening. The latter has been reported for flesh-toned and red tattoos. Such a complication has never been reported for the laser treatment of a yellow tattoo in the dermatological literature. We describe a case of tattoo ink darkening of a yellow tattoo after treatment with the 532 nm quality-switched Neodymium : Ytrrium-Aluminium Garnet laser to highlight clinicopathological features. The mechanism by which some tattoos darken after laser treatment is not clearly understood. We review darkening of tattoos after laser treatment to raise awareness of this important complication. This paper will help to facilitate discussions with the patient and in obtaining informed consent prior to commencing treatment. Tattoo ink darkening of a yellow tattoo adds to the growing list of complications resulting from attempts at tattoo removal. PMID:12372085

  18. A 5.9-mJ 500-Hz Electro-Optic Q-Switched 1053 nm Nd:LiLuF4 Laser

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Zhu, Xiao-Lei; Lu, Ting-Ting; Ma, Jian; Hang, Yin; Chen, Wei-Biao

    2014-02-01

    An efficient and high power 1053 nm electro-optic Q-switched Nd:LiLuF4 laser, end-pumped by two fiber coupled laser diodes at wavelength 806 nm, is reported for the first time. With an incident pump power of 24.4 W, the maximum laser output power of 7.3 W is achieved in free-running mode, and the optical conversion efficiency is 29.8%. For the Q-switched operation, the shortest pulse width of 17 ns is obtained at the pulse repetition rate of 500 Hz, corresponding to the pulse energy of 5.9 mJ with the peak power of 0.35 MW.

  19. Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber.

    PubMed

    Cole, Brian; Goldberg, Lew; Trussell, C Ward; Hays, Alan; Schilling, Bradley W; McIntosh, Chris

    2009-02-01

    A method for optical triggering of a Q-switched Nd:YAG laser by direct bleaching of a Cr:YAG saturable absorber is described. This method involves the bleaching of a thin sheet of the saturable absorber from a direction orthogonal to the lasing axis using a single laser diode bar, where the Cr:YAG transmission increased from a non-bleached value of 47% to a bleached value of 63%. For steady state operation of a passively Q-switched laser (PRF=10 Hz), the pulse-to-pulse timing jitter showed approximately 12X reduction in standard deviation, from 241 nsec for free running operation to 20 nsec with optical triggering. PMID:19189006

  20. Savior of post-blepharoepicanthoplasty scarring: Novel use of a low-fluence 1064-nm Q-switched Nd:YAG laser.

    PubMed

    Tian, Wei Cheng Brian Anthony

    2016-01-01

    Blepharoplasty with medial epicanthoplasty is popular in Asia. However, known complications include scarring, which can take the form of hypertrophic scars or keloids. Treatments for scars include pressure dressing, silicone gels, retinoic acids, radiotherapy, cryotherapy, triamcinolone injections, and surgical revision. These methods, however, have variable outcomes. Recently, there is an interest in post-surgical scar remodeling with lasers. Although the 1064-nm Q-switched Nd:YAG is primarily a pigment laser, it has recently been shown to be effective for treating scars. In the management of post-blepharoepicanthoplasty scarring, this is certainly unheard of. In this paper, we present a novel technique of treating a patient with post-blepharoepicanthoplasty hypertrophic scarring with a low-fluence 1064-nm Q-switched Nd:YAG laser. PMID:26820981

  1. Numerical Simulations of a 2.05 μm Q-switched Ho:YLF Laser for CO2 IPDA Space Remote Sensing

    NASA Astrophysics Data System (ADS)

    Barrientos Pellegrino, Jessica; Edouart, Dimitri; Gibert, Fabien; Cenac, Claire

    2016-06-01

    We report on numerical simulations of the performances of a 2.05 μm double pulse Q-switched Ho:YLF laser for the monitoring of CO2 from space. A Q-switched Holmium laser set-up based on a MOPA configuration is proposed to fulfill the requirements of a IPDA space-borne measurement. Double pulse operation is considered to obtain a 250 μs delay time between the ON and OFF pulse emissions. Numerical simulations results show that up to 40 mJ ON pulse can be extracted from the Ho:YLF laser at a repetition rate of 350 Hz with an optical efficiency of 17 %.

  2. 2.78 μm passively Q-switched Er3+-doped ZBLAN fiber laser based on PLD-Fe2+:ZnSe film

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Feng, Guoying; Zhang, Hong; Yang, Xianheng; Dai, Shenyu; Zhou, Shouhuan

    2016-07-01

    Based on the pulsed laser deposition (PLD) method, we first fabricated a mid-infrared Fe2+:ZnSe film saturable absorber (SA). By employing the PLD Fe2+:ZnSe film SA, we have demonstrated a passively Q-switched double-clad Er3+-doped ZBLAN fiber laser operating at a wavelength of 2.78 μm. Stable Q-switched pulses with pulse energy of 7.98 μJ and pulse duration of 0.742 μs, corresponding to a peak power of 10.76 W, were obtained at a repetition rate of 102.94 kHz. The maximum average output power is 822 mW. Our results demostrate that the PLD-Fe2+:ZnSe film SA is promising for high power pulse generation in compact mid-infrared fiber lasers.

  3. First clinical experience with a Q-switched neodymium:YAG laser for urinary calculi.

    PubMed

    Hofmann, R; Hartung, R; Schmidt-Kloiber, H; Reichel, E

    1989-02-01

    Animal studies using a high intensity nanosecond pulsed neodymium:YAG laser did not reveal any serious tissue damage. Following these investigations patient treatment was begun in June 1987. Laser energy of a neodymium:YAG laser with an 8 nsec. pulse duration and a repetition rate of up to 50 Hz. was coupled into a flexible 600 resp. 400 micron. quartz fiber. Laser-induced breakdown was created with 35 to 50 mJ. at the fiber tip, resulting in a shock wave that disintegrated the calculus into tiny fragments. A total of 56 patients with 58 calculi (54 ureteral and 4 kidney stones) was treated from June 1987 to March 1988. Of the calculi 48 could be fragmented completely, while 6 others were reduced to a size small enough to be removed with forceps. Four stones composed of calcium oxalate monohydrate could not be disintegrated. The combination of laser stone disintegration with flexible ureterorenoscopy implies the possibility of an atraumatic, 1-step procedure for fragmentation of ureteral and kidney calculi. PMID:2563297

  4. Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber laser at 2.8 μm.

    PubMed

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

    2015-09-21

    Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multilayer 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 μm. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 μJ/cm(2), respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 μJ and pulse width of 1.18 μs 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-μm fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers. PMID:26406672

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

    PubMed

    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. PMID:23037409

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

    NASA Astrophysics Data System (ADS)

    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.

  7. As-grown uniform MoS2/mica saturable absorber for passively Q-switched mode-locked Nd:GdVO4 laser

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

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

    2015-01-01

    The mechanisms responsible for variable responses of cosmetic tattoos to Q-switched laser removal treatment remain unclear. We sought to investigate the properties of tattoo inks that may affect the efficacy of laser-assisted tattoo removal. The absorption of white, brown, and black inks before and after Q-switched neodymium-doped yttrium aluminum garnet laser irradiation were analyzed by a reflectance measurement system. Rats were tattooed using the three inks and treated with the same laser for two sessions. Skin biopsies were taken from the treated and untreated sites. Black ink showed strong absorption, reduced after laser irradiation, over the entire spectrum. White ink had low absorption over the visible light spectrum, and brown ink had strong absorption at 400-550 nm wavelengths. White and brown inks turned dark after laser exposure, and the absorption of laser-darkened inks were intermediate between their original color and black ink. White, brown, and black tattoos in rat skin achieved poor, fair to good, and excellent responses to laser treatment, respectively. Transmission electron microscopy showed that white tattoo particles were the largest, brown were intermediate, and black were the smallest before laser. After laser treatment, white and brown tattoo particles were mixtures of large and small particles, while black particles showed overall reduction in number and size. Black tattoo ink's excellent response to Q-switched lasers was associated with its strong absorption and small particle size. White tattoo ink's poor response was associated with its poor absorption, even after laser darkening, and large particle size. PMID:25249494

  9. Resonant photoacoustic detection of NO2 traces with a Q-switched green laser

    NASA Astrophysics Data System (ADS)

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

    2003-01-01

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

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

    SciTech Connect

    Zeng, X. E-mail: dmitri.boiko@csem.ch; Stadelmann, T.; Grossmann, S.; Hoogerwerf, A. C.; Boïko, D. L. E-mail: dmitri.boiko@csem.ch; Sulmoni, L.; Lamy, J.-M.; Grandjean, N.

    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.

  11. Generation of high-peak power 532-nm green pulses from composite, all-ceramics, passively Q-switched Nd:YAG/Cr4+:YAG laser

    NASA Astrophysics Data System (ADS)

    Salamu, Gabriela; Ionescu, Alina; Brandus, Catalina; Grigore, Oana; Pavel, Nicolaie; Dascalu, Traian

    2013-06-01

    Laser pulses at 1.06 μm with 2.5-mJ energy and 3.1-MW peak power have been obtained from a composite, all polycrystalline ceramics, passively Q-switched 1.1-at.% Nd:YAG/Cr4+:YAG laser that was quasi-continuous-wave pumped with diode lasers. Single-pass frequency doubling with LiB3O5 nonlinear crystal at room temperature yielded green laser pulses at 532 nm with energy of 0.36-mJ and 0.45-MW peak power; the infrared-to-green conversion efficiency was 0.27.

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

    NASA Astrophysics Data System (ADS)

    Zeng, X.; Sulmoni, L.; Lamy, J.-M.; Stadelmann, T.; Grossmann, S.; Hoogerwerf, A. C.; Grandjean, N.; Boïko, D. L.

    2015-02-01

    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.

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

    PubMed

    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. PMID:25401559

  14. 1.12-W Q-switched Yb:KGW laser based on transmission-type Bi2Se3 saturable absorber

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Hui; Tian, Jin-Rong; Hu, Meng-Ting; Xu, Run-Qin; Dou, Zhi-Yuan; Yu, Zhen-Hua; Song, Yan-Rong

    2015-02-01

    We present a passively Q-switched Yb:KGW laser based on a transmission-type saturable absorber of topological insulator: Bi2Se3. The saturable absorber is prepared on a 0.17-mm glass substrate and can translate intra-cavity for best performance nearly without influence on the laser mode. At a maximum pump power of 13.7 W, the central wavelength, pulse duration, repetition rate, and pulse energy of Q-switched pulse are 1043 nm, 1.5 μs, 175.4 kHz, 6.39 μJ, respectively. The maximum output power is 1.12 W. To our knowledge, this is the highest average output power from passively Q-switched lasers with topological insulator saturable absorbers. Project supported by the National Basic Research Program of China (Grant No. 2013CB922404), the National Natural Science Foundation of China (Grant No. 61177047), and the Beijing Municipal Education Commission Project, China (Grant No. KM201010005007).

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

    PubMed

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

    2016-03-01

    Pigmentation secondary to minocycline ingestion is an uncommon adverse event affecting 3.7-14.8% of treated individuals for which few effective therapies are available. Three patterns of minocycline pigmentation have a characteristic clinical and histological appearance. The pigment composition in each variety is different and occurs at varying skin depths. Accordingly, a tailored approach according to the type of minocycline pigmentation is crucial for treatment success. The purpose of this intervention was to evaluate the efficacy of non-ablative fractional photothermolysis in combination with the Q-switched alexandrite laser for the treatment of type I minocycline pigmentation on the face. A patient with type I minocycline pigmentation was treated with non-ablative 1550-nm fractional photothermolysis followed immediately by 755-nm Q-switched alexandrite laser and then observed clinically to determine the outcome of this modality. The patient was seen in clinic 1 month later following her single treatment session and 100% clearance of all blue facial pigment was observed. Non-ablative fractional photothermolysis in combination with the 755-nm Q-switched alexandrite laser should be considered for treatment of type I minocycline pigmentation. PMID:26718463

  16. 808-nm diode-pumped dual-wavelength passively Q-switched Nd:LuLiF4 laser with Bi-doped GaAs

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  17. High-peak-power flashlamp-pumped passively Q-switched Nd:YAG laser with AlGaInAs quantum wells as a saturable absorbers

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    We demonstrate an AlGaInAs saturable absorber with a periodic quantum wells (QWs)/barrier structure that can be used to achieve an efficient high-peak-power and high-pulse-energy passively flashlamp-pumped Q-switched Nd:YAG laser at 1.06 um. The barrier layers are designed to locate the QW groups in the region of the nodes of the lasing standing wave to avoid damage. With an incident pump voltage of 14.5 J, a single pulse was generated with a pulse energy of 14 mJ and a Q-switched pulse width of 13 ns. The maximum peak power was greater than 1.08 MW.

  18. 1.06 μm Q-switched ytterbium-doped fiber laser using few-layer topological insulator Bi₂Se₃ as a saturable absorber.

    PubMed

    Luo, Zhengqian; Huang, Yizhong; Weng, Jian; Cheng, Huihui; Lin, Zhiqing; Xu, Bin; Cai, Zhiping; Xu, Huiying

    2013-12-01

    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 firstly 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 μm is achieved. The Q-switched pulses have the shortest pulse duration of 1.95 μs, 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 μm waveband, revealing its potential as another broadband SA (like graphene). PMID:24514504

  19. PVP-Assisted Solvothermal Synthesis of High-Yielded Bi2Te3 Hexagonal Nanoplates: Application in Passively Q-Switched Fiber Laser

    NASA Astrophysics Data System (ADS)

    He, Xin; Zhang, Hang; Lin, Wei; Wei, Rongfei; Qiu, Jianrong; Zhang, Mei; Hu, Bin

    2015-10-01

    High-yielded Bi2Te3 hexagonal nanoplates were fabricated via a facile solvothermal method with the assistance of poly (vinyl pyrrolidone) (PVP). Effects of PVP molecular weight and concentration on the morphology and size distribution of the products were illustrated in this study. Molecular weight of PVP is significant for determining the morphology of Bi2Te3. The hexagonal nanoplates with high yield were obtained in the presence of PVP with molecular weight of 40000-45000. The average size and size distribution of Bi2Te3 nanoplates can be slightly varied by controlling concentration of PVP. High-yielded Bi2Te3 nanoplates exhibit characteristics of saturable absorption, identified by open-aperture Z-scan technique. The synthesized Bi2Te3 nanoplates with large saturation intensity of 4.6 GW/cm2 and high modulation depth of 45.95% generated a stable passively Q-switched fiber laser pulse at 1.5 μm. In comparison with recently reported Q-switched fiber lasers utilizing exfoliated Bi2Te3 nanosheets, our passive Q-switching operations could be conducted at a relatively low threshold power of 30.2 mW or a quite high output power of 99.45 mW by tuning the cavity parameters.

  20. PVP-Assisted Solvothermal Synthesis of High-Yielded Bi2Te3 Hexagonal Nanoplates: Application in Passively Q-Switched Fiber Laser.

    PubMed

    He, Xin; Zhang, Hang; Lin, Wei; Wei, Rongfei; Qiu, Jianrong; Zhang, Mei; Hu, Bin

    2015-01-01

    High-yielded Bi2Te3 hexagonal nanoplates were fabricated via a facile solvothermal method with the assistance of poly (vinyl pyrrolidone) (PVP). Effects of PVP molecular weight and concentration on the morphology and size distribution of the products were illustrated in this study. Molecular weight of PVP is significant for determining the morphology of Bi2Te3. The hexagonal nanoplates with high yield were obtained in the presence of PVP with molecular weight of 40000-45000. The average size and size distribution of Bi2Te3 nanoplates can be slightly varied by controlling concentration of PVP. High-yielded Bi2Te3 nanoplates exhibit characteristics of saturable absorption, identified by open-aperture Z-scan technique. The synthesized Bi2Te3 nanoplates with large saturation intensity of 4.6 GW/cm(2) and high modulation depth of 45.95% generated a stable passively Q-switched fiber laser pulse at 1.5 μm. In comparison with recently reported Q-switched fiber lasers utilizing exfoliated Bi2Te3 nanosheets, our passive Q-switching operations could be conducted at a relatively low threshold power of 30.2 mW or a quite high output power of 99.45 mW by tuning the cavity parameters. PMID:26511763

  1. Q-switched thulium-doped fiber laser operating at 1940 nm region using a pencil-core as saturable absorber

    NASA Astrophysics Data System (ADS)

    Latiff, A. A.; Shamsudin, H.; Ahmad, H.; Harun, S. W.

    2016-04-01

    Q-switched thulium-doped fiber laser (TDFL) is demonstrated using pencil-core flakes as a saturable absorber (SA) for the first time. The SA was fabricated by exfoliating pencil-core flakes on adhesive tape surface, then repeatedly folded over the tape until the flakes homogenously deposited on the tape. A small piece of the tape is sandwiched between two ferrules and incorporated in TDFL cavity to realize a stable Q-switching pulse train. By increasing the 1552-nm pump power from 389 to 431 mW, the repetition rate of the TDFL increases from 14.95 to 34.60 kHz while the pulse width decreases from 6.70 to 4.69 μs. The maximum pulse energy of 46.05 nJ is generated with repetition rate and pulse width of 21.25 kHz and 6.27 μs, respectively. To the best our knowledge, this is a first demonstration SA from mundane object as alternative to commercial bulk graphite for Q-switched fiber laser.

  2. PVP-Assisted Solvothermal Synthesis of High-Yielded Bi2Te3 Hexagonal Nanoplates: Application in Passively Q-Switched Fiber Laser

    PubMed Central

    He, Xin; Zhang, Hang; Lin, Wei; Wei, Rongfei; Qiu, Jianrong; Zhang, Mei; Hu, Bin

    2015-01-01

    High-yielded Bi2Te3 hexagonal nanoplates were fabricated via a facile solvothermal method with the assistance of poly (vinyl pyrrolidone) (PVP). Effects of PVP molecular weight and concentration on the morphology and size distribution of the products were illustrated in this study. Molecular weight of PVP is significant for determining the morphology of Bi2Te3. The hexagonal nanoplates with high yield were obtained in the presence of PVP with molecular weight of 40000–45000. The average size and size distribution of Bi2Te3 nanoplates can be slightly varied by controlling concentration of PVP. High-yielded Bi2Te3 nanoplates exhibit characteristics of saturable absorption, identified by open-aperture Z-scan technique. The synthesized Bi2Te3 nanoplates with large saturation intensity of 4.6 GW/cm2 and high modulation depth of 45.95% generated a stable passively Q-switched fiber laser pulse at 1.5 μm. In comparison with recently reported Q-switched fiber lasers utilizing exfoliated Bi2Te3 nanosheets, our passive Q-switching operations could be conducted at a relatively low threshold power of 30.2 mW or a quite high output power of 99.45 mW by tuning the cavity parameters. PMID:26511763

  3. Passive Q-switching of a Tm,Ho:KLu(WO4)2 microchip laser by a Cr:ZnS saturable absorber.

    PubMed

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

    2016-05-10

    A diode-pumped Tm,Ho:KLu(WO4)2 microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14  ns/9  μJ at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9  ns/10.4  μJ/8.2  kHz pulses were generated at 2061.1 nm, corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented, predicting the pulse energy and duration. The simulations are in good agreement with the experimental results. PMID:27168288

  4. Q-switched lasing at 2 {mu}m in a Tm{sup 3+}:YAlO{sub 3} laser

    SciTech Connect

    Ushakov, S N; Khromov, M N; Shestakov, A V

    2009-05-31

    The parameters of a Q-switched longitudinally-diode-pumped Tm{sup 3+}:YAlO{sub 3} laser are presented. The pulse repetition rate is f = 1-15 Hz. The maximum average output power is 5 W (at f = 5-15 kHz), the minimum pulse duration is 130 ns (f = 1 kHz), the efficiency is 26% (with the slope efficiency of 58%). The laser wavelength under pumping in the region of 803-805 nm is 1.99 {mu}m. (lasers and amplifiers)

  5. Widely tunable eye-safe laser by a passively Q-switched photonic crystal fiber laser and an external-cavity optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Chang, H. L.; Zhuang, W. Z.; Huang, W. C.; Huang, J. Y.; Huang, K. F.; Chen, Y. F.

    2011-09-01

    We report on a widely tunable passively Q-switched photonic crystal fiber (PCF) laser with wavelength tuning range up to 80 nm. The PCF laser utilizes an AlGaInAs quantum well/barrier structure as a saturable absorber and incorporates an external-cavity optical parametric oscillator (OPO) to achieve wavelength conversion. Under a pump power of 13.1 W at 976 nm, the PCF laser generated 1029-nm radiation with maximum output energy of 750 μJ and was incident into an external-cavity OPO. The output energy and peak power of signal wave was found to be 138 μJ and 19 kW, respectively. By tuning the temperature of nonlinear crystal, periodically poled lithium niobate (PPLN), in the OPO, the signal wavelength in eye-safe regime from 1513 to 1593 nm was obtained.

  6. Treatment of melasma in Caucasian patients using a novel 694-nm Q-switched ruby fractional laser

    PubMed Central

    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

  7. High-power CW and passively Q-switched laser operation of Yb:GdCa4O(BO3)3 crystal

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowen; Wang, Lisha; Liu, Junhai; Guo, Yunfeng; Han, Wenjuan; Xu, Honghao; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    We demonstrate efficient high-power CW and passively Q-switched operations of Yb:GdCa4O(BO3)3 lasers. An output power of 18.2 W is generated at 1031.5 nm in CW mode, with optical-to-optical and slope efficiencies being respectively 55% and 70%, with respect to incident pump power. In passively Q-switched operation with a Cr4+:YAG crystal as saturable absorber, a maximum average output power of 15.6 W is produced at a pulse repetition rate of 91 kHz, with an optical-to-optical efficiency of 44%. Low-repetition-rate Q-switched action is also realized, generating an average output power of 4.2 W at 5.7 kHz, the resulting pulse energy and duration are 737 μJ and 3.6 ns, leading to a peak power amounting to 205 kW.

  8. Microfiber-coupler-assisted control of wavelength tuning for Q-switched fiber laser with few-layer molybdenum disulfide nanoplates.

    PubMed

    Chen, Jin-hui; Deng, Guo-qing; Yan, Shao-cheng; Li, Cheng; Xi, Kai; Xu, Fei; Lu, Yan-qing

    2015-08-01

    Based on the liquid exfoliated method, we obtained the few-layer molybdenum disulfide (MoS2) nanoplates solution. By thermal evaporation method, we directly deposited MoS2 thin film onto the facet of a fiber patch cord. The modulation depth of the film is as high as 29%, and a Q-switched fiber laser was achieved. We also provided a new method to continuously tune the output laser with a tuning sensitivity of ∼5.5  nm/(1%  strain) by controlling the cavity loss with a strained microfiber coupler (MFC). PMID:26258361

  9. Diode-pumped Nd:YAG ceramic laser at 946 nm passively Q-switched with a Cr 4+:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    Li, Ping; Zhang, Huanian; Chen, Xiaohan; Wang, Qingpu

    2012-04-01

    We demonstrate a diode-pumped Nd:YAG ceramic laser with emission at 946 nm that is passively Q-switched by single-crystal Cr 4+:YAG saturable absorber. An average output power of 1.7 W is measured under 18.4 W of incident power using an output mirror with transmission T=4%. The corresponding optical-to-optical efficiency is 9.2%. The laser runs at a pulse repetition rate of 120 kHz and delivers pulses with energy of 14 μJ and duration of 80 ns, which corresponds to a peak power of 175 W.

  10. Q-switching of an alexandrite laser by (F/sup +//sub 2/)/sub A/ color centers in NaF

    SciTech Connect

    Kolyago, S.S.; Matrosov, V.N.; Pestryakov, E.V.; Trunov, V.I.; Gusev, Y.L.; Shkadarevich, A.P.

    1985-12-01

    Investigations were made of the characteristics of (F/sup +//sub 2/)/sub A/ color centers in NaF and of the spectral and lasing properties of an alexandrite laser Q-switched by centers of this type. When a Lyot filter and a switch having an initial transmission of approx.70% were used in this laser resonator, pulses of 80--100 nsec duration with a spectral width of approx.0.1 cm/sup -1/ and a tuning range of 0.73--0.783 ..mu.. were obtained under pulse-periodic conditions (12.5 Hz).

  11. Compact repetitively Q-switched Yb:YCa4O(BO3)3 laser with an acousto-optic modulator

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowen; Xu, Honghao; Han, Wenjuan; Yi, Hongying; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-07-01

    Repetitively Q-switched operation was achieved with a Yb:YCa4O(BO3)3 laser in a wide repetition rate range from 20 down to 0.1 kHz. An output power of 6.81 W at 20 kHz was generated with pulse duration of 42 ns; while operated at a low repetition rate of 0.1 kHz, the laser produced 0.53 W of output power with pulse width of 21 ns, the resulting pulse energy and peak power amounted respectively to 5.3 mJ and 252.4 kW.

  12. High efficient Q-switched Nd:YLF laser operating at 523.5nm with near-diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Lu, Tingting; Huang, Minjie; Liu, Dan; He, Yan; Zhu, Xiaolei

    2013-05-01

    An efficient and compact green laser at 523.5 nm was generated by intracavity frequency doubling of a diode end-pumped conductively cooled Q-switched Nd:YLF laser at 1047 nm. With an incident pump pulse energy of 28.6 mJ at 250 Hz repetition rate, pulse energy of 8 mJ was obtained with a pulse width of 10 ns, corresponding to an optical- optical conversion efficiency of 28%. The beam quality factors were Mx 2 =1.35,My 2 =1.21.

  13. Efficient 1645 nm continuous-wave and Q-switched Er:YAG laser pumped by 1532 nm narrow-band laser diode.

    PubMed

    Zhu, Liang; Wang, Mingjian; Zhou, Jun; Chen, Weibiao

    2011-12-19

    Energy transfer upconversion induced thermal effects are mainly responsible for the low efficiency of laser diode pumped Er:YAG lasers. The current work adopts Er:YAG rods with 0.25% Er(3+) doping concentration, instead of the commonly used rods with 0.5% Er(3+) doping concentration. Results show that the thermal effect is greatly alleviated. A continuous-wave output of 10.2 W is obtained using 31 W incident pump power. Optical-optical efficiency is approximately 33%. Slope efficiency, with respect to the absorbed pump power, is as high as 83%, which is close to the quantum efficiency. In a Q-switched operation, 7 mJ pulses with a pulse width of ~65 ns are obtained at 100 Hz PRF. PMID:22274263

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  15. 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.

    PubMed

    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 (< 10 ns), and a repetition rate of 10 Hz has been successful in the treatment of melasma. A mistake commonly made during laser toning is to scorch scalp 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. PMID:19486060

  16. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    NASA Astrophysics Data System (ADS)

    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. Diode-pumped acousto-optically Q-switched high-repetition-rate Nd:YAG lasers at 946 and 473 nm by intracavity frequency-doubling

    NASA Astrophysics Data System (ADS)

    Chen, F.; Yu, X.; Guo, J.; Guo, L. H.; Yang, G. L.; Xie, J. J.; Zhang, L. M.; Geng, Y. M.; Li, S. M.; Li, D. J.; Shao, C. L.; Meng, F. J.; Zhang, C. S.; Yan, R. P.

    2011-10-01

    A diode-pumped acousto-optically (AO) Q-switched high-repetition-rate Nd:YAG lasers at 946 and 473 nm by intracavity frequency-doubling were reported in this paper. Using a compact V-type laser cavity, a maximum average output power of 4.5 W 946 nm laser was obtained at an operating repetition rate of 10 kHz, corresponding to an optical conversion efficiency of 10.5% and a slope efficiency of 15.6%. With a BiBO crystal as the intracavity frequency-doubler, 1.35 W 473 nm pulsed laser was achieved at 10 kHz. The peak power of the Q-switched blue pulse was up to 4.1 kW, with a pulse width of 33.1 ns. Then, the long-term power instability was less than 1%. Moreover, stable pulsed operation of 946 nm and 473 nm lasers can even reach 50 kHz.

  18. Tattoo removal in micropigs with low-energy pulses from a Q-switched Nd:YAG laser at 1064 nm

    NASA Astrophysics Data System (ADS)

    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. High-order Stokes generation in a KTP Raman laser pumped by a passively Q-switched ND:YLF laser

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    High-order Stokes wave was observed in an x-cut KTP crystal based on stimulated Raman scattering (SRS) pumped by a passively Q-switched Nd:YLF laser with a Cr4+:YAG saturable absorber. Output spectra including the fundamental wave at 1047 nm and six Stokes wavelengths at 1077 nm, 1110 nm, 1130 nm, 1143 nm, 1164 nm, 1180 nm based on two Raman frequency shift at 267.4 cm-1 and 693.0 cm-1 were obtained simultaneously. We also detected green light generation with output power of 12 mW from self frequency mixing in the KTP crystal. The maximum total output power reached 452 mW at the repetition frequency of 8.1 kHz, corresponding to the optical-to-optical conversion efficiency of 4.61% and pump-to-Raman conversion efficiency of 3.6%.

  20. 10.2-W Q-switched intracavity frequency-doubled Nd:YVO(4)/LBO red laser double-end-pumped by laser-diode-arrays.

    PubMed

    Qin, Wan; Du, Chenlin; Ruan, Shuangchen; Wang, Yuncai

    2007-02-19

    We report a high-power diode-double-end-pumped Q-switched Nd:YVO4 red laser through intracavity frequency-doubling with a type-I critical phase-matched LBO crystal. At a repetition frequency of 21.72 kHz, a maximum average output power of 10.2 W at 671 nm was measured to while the incident pump power was 78.4 W, the corresponding optical conversion efficiency was 13.0%, with a pulse width of about 94 ns and a pulse energy of 469.6 muJ, the peak power was 5.0 kW. At an average output power around 9.6 W a power stability better than 2.3% was maintained for half an hour. PMID:19532392

  1. The Effect of Q-Switched Nd:YAG 1064 nm/532 nm Laser in the Treatment of Onychomycosis In Vivo

    PubMed Central

    Kalokasidis, Kostas; Onder, Meltem; Trakatelli, Myrto-Georgia; Richert, Bertrand; Fritz, Klaus

    2013-01-01

    In this prospective clinical study, the Q-Switched Nd:YAG 1064 nm/532 nm laser (Light Age, Inc., Somerset, NJ, USA) was used on 131 onychomycosis subjects (94 females, 37 males; ages 18 to 68 years). Mycotic cultures were taken and fungus types were detected. The laser protocol included two sessions with a one-month interval. Treatment duration was approximately 15 minutes per session and patients were observed over a 3-month time period. Laser fluencies of 14 J/cm2 were applied at 9 billionths of a second pulse duration and at 5 Hz frequency. Follow-up was performed at 3 months with mycological cultures. Before and after digital photographs were taken. Adverse effects were recorded and all participants completed “self-evaluation questionnaires” rating their level of satisfaction. All subjects were well satisfied with the treatments, there were no noticeable side effects, and no significant differences were found treating men versus women. At the 3-month follow-up 95.42% of the patients were laboratory mycologically cured of fungal infection. This clinical study demonstrates that fungal nail infections can be effectively and safely treated with Q-Switched Nd:YAG 1064 nm/532 nm laser. It can also be combined with systemic oral antifungals providing more limited treatment time. PMID:24396343

  2. Experimental and theoretical study of passively Q-switched Yb:YAG laser with GaAs saturable absorber near 1050 nm

    NASA Astrophysics Data System (ADS)

    Chu, Hongwei; Zhao, Shengzhi; Yang, Kejian; Li, Yuefei; Li, Dechun; Li, Guiqiu; Zhao, Jia; Qiao, Wenchao; Xu, Xiaodong; Di, Juqing; Zheng, Lihe; Xu, Jun

    2014-03-01

    A diode-end-pumped passively Q-switched ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser with gallium arsenide (GaAs) wafer as saturable absorber has been realized. In the experiment, two pieces of GaAs wafers with respective thicknesses of 400 and 700 μm were used respectively. The output laser characteristics such as the pulse duration, single pulse energy and peak power, have been measured. By using thicker GaAs wafer as saturable absorber, a minimum pulse duration of 3.5 ns was obtained with an average output power of 361 mW and a pulse repetition rate (PRR) of 25 kHz, corresponding to a single pulse energy of 19.6 μJ and a peak power of 5.7 kW. With a 400 μm-thick GaAs wafer as saturable absorber, a maximum output power of 469 mW was achieved. The central wavelength of the laser was measured to be 1050.4 nm at pump power of 7.8 W and dual wavelength operation peaked at 1049.3 nm and 1051.6 nm was observed at a high pump power of 10 W. By considering Gaussian spatial distribution and the thermal effects in the gain medium, the coupled rate equations for passively Q-switched Yb:YAG laser with GaAs saturable absorber were given.

  3. 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.

    PubMed

    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. PMID:24514058

  4. High-peak-power, short-pulse-width, LD end-pumped, passively Q-switched Nd:YAG 946 nm laser

    NASA Astrophysics Data System (ADS)

    Yan, Renpeng; Yu, Xin; Ma, Yufei; Li, Xudong; Chen, Deying; Yu, Junhua

    2012-10-01

    High-peak-power, short-pulse-width diode pumped 946 nm Nd:YAG laser in passively Q-switching operation with Cr4+:YAG is reported. The highest average output power reaches 3.4 W using the Cr4+:YAG with initial transmissivity T0=95%. When the T0=90% Cr4+:YAG is employed, the maximum peak power of 31.4 kW with a pulse width of 8.3 ns at 946 nm is generated.

  5. Diode-pumped passively Q-switched Nd:YVO4 green laser with a periodically poled KTP and Cr4+:YAG saturable absorber.

    PubMed

    Li, Guiqiu; Zhao, Shengzhi; Yang, Kejian; Li, Dechun

    2006-03-10

    A diode-pumped passively Q-switched Nd:YVO4 green laser with a periodically poled KTP and Cr4+:YAG saturable absorber is realized. The dependences of pulse repetition rate, pulse energy, pulse width, and peak power on incident pump power are measured for the generated green-light pulses. A rate-equation model is introduced to theoretically analyze the results obtained in the experiment, in which the spatial distribution of the intracavity photon density is taken into account. The numerical solutions of the rate equations agree with the experimental results. PMID:16572700

  6. Facial scars after a road accident--combined treatment with pulsed dye laser and Q-switched Nd:YAG laser.

    PubMed

    Martins, Andréa; Trindade, Felicidade; Leite, Luiz

    2008-09-01

    We report the case of a woman who presented with several facial scars following a road accident. Treatment was carried out using combined laser treatment with pulsed dye laser (PDL) and Q-switched neodymium:yttrium-aluminum-garnet laser (QS Nd:YAG laser). No side effects or complications from treatment were noted or reported. The patient had very good cosmetic results with this combined technique. A variety of facial scars - erythematous, pigmented, atrophic, and hypertrophic - may occur as a result of trauma, surgery, burns, and skin disease. Surgery with other adjunctive methods including radiotherapy, intralesional steroids, and pressure therapy have shown variable results. Laser treatment has been attempted for scar revision since the 1980s. The PDL is the optimal treatment for reducing scar bulk and symptoms. It also decreases erythema and telangiectasia associated with scars, normalizes the skin surface texture, and improves the scar pliability. The QS Nd:YAG laser (1064 nm) is highly effective for traumatic tattoo removal, resulting in complete clearance in the majority of cases. PMID:18789060

  7. Novel technique to treat melasma in Chinese: The combination of 2940-nm fractional Er:YAG and 1064-nm Q-switched Nd:YAG laser.

    PubMed

    Tian, Wei Cheng Brian Anthony

    2016-04-01

    Melasma is one of the most common pigmented lesions in Chinese women. Although topical therapies are the mainstay treatment, lasers are being used increasingly to treat pigmented lesions. Laser treatment of melasma is however still controversial. This is because lasers have not been able to produce complete clearance of melasma and recurrence rates are high. Laser treatments also cause complications such as hypopigmentation and post-inflammatory hyperpigmentation. In this article, we report on a novel technique using a combination of fractional 2940-nm Er:YAG and 1064-nm Q-switched Nd:YAG lasers. We achieved a rapid improvement in two cases of melasma in Chinese type III skin. The improvement was seen rapidly within a month of treatment. Follow-up at 6 months showed sustained results with no complications. This novel technique is able to safely confer excellent and sustained clearance within a short treatment time. PMID:26836057

  8. Experimental investigation of the spectro-temporal dynamics of the light pulses of Q-switched Nd:YAG lasers and nanosecond optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    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.

  9. Experimental Study on Dual Wavelength and Dual Pulse Q-Switched Frequency Doubling on a Tunable Cr:LiSAF Laser

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Shui; Zhang, Yi-Shi; Yu, Jin-Wang; Fang, Jian; Liu, Song-Hao

    2009-09-01

    A flashlamp-pumped Cr:LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32 mJ/pulse producing the total output energy of 64 mJ and the pulse width is about 27 ns at 850 nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength (448.1 nm and 449.15 nm) and dual pulse laser. The output for one wavelength is about 10.3 mJ and the line width is less than 0.02 nm.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Generation of Q-switched mode locking controlled rectangular noise-like soliton bunching in a Tm-doped fiber laser.

    PubMed

    Qiao, Tian; Chen, Weicheng; Lin, Wei; Yang, Zhongmin

    2016-08-01

    We report on an interesting phenomenon of the combination of Q-switched mode locked pulses (QSMLP) and rectangular noise-like pulses (RNLP) as a unit in a Tm-doped ring fiber laser which contains a Fabry-Perot (F-P) subcavity based on the nonlinear polarization evolution (NPE) technique. The RNLP and QSMLP are independently generated in the ring cavity and F-P subcavity, respectively. A notable characteristic is that the physical parameters of RNLP, e.g. repetition rate and pulse duration, are controlled by QSMLP. Thus, they form as a composite bunching, which is termed as "Q-switched mode locking controlled rectangular noise-like soliton bunching (QRNSB)". Further investigation shows that the existence of QRNSB only occurs in high pumping conditions, while both fundamental mode-locking pulses and the coexistence of QSMLP and solitons are achieved in low pumping ones. Our work can enrich the understanding of the nonlinear dynamics in fiber lasers. PMID:27505838

  12. 400 µJ 79 ns amplified pulses from a Q-switched fiber laser using an Yb(3+)-doped fiber saturable absorber.

    PubMed

    Moore, Sean W; Soh, Daniel B S; Bisson, Scott E; Patterson, Brian D; Hsu, Wen L

    2012-10-01

    We report a passively Q-switched all-fiber laser using a large mode area (LMA) Yb(3+)-doped fiber cladding-pumped at 915 nm and an unpumped single-mode Yb(3+)-doped fiber as the saturable absorber (SA). The saturable absorber fiber and gain fiber were coupled with a free-space telescope to optimize the coupling efficiency between the disparate fibers, preferentially bleaching the SA fiber before gain depletion in the pumped fiber. Using this scheme we first demonstrate a Q-switched oscillator with 40 μJ 79 ns pulses at 1026 nm, and show that pulses can be generated from 1020 nm to 1040 nm. The associated peak power of the oscillator alone is more than two orders of magnitude larger than that reported in previous experimental studies using an Yb(3+)-doped fiber as a saturable absorber. We further demonstrate an amplified pulse energy of 0.4 mJ using an Yb(3+)-doped cladding pumped fiber amplifier. Experimental studies in which the saturable absorber length, pump times, and wavelengths are independently varied reveal the impact of these parameters on laser performance. PMID:23188343

  13. Compact high-pulse-energy passively Q-switched Nd:YLF laser with an ultra-low-magnification unstable resonator: application for efficient optical parametric oscillator.

    PubMed

    Cho, C Y; Huang, Y P; Huang, Y J; Chen, Y C; Su, K W; Chen, Y F

    2013-01-28

    We exploit an ultra-low-magnification unstable resonator to develop a high-pulse-energy side-pumped passively Q-switched Nd:YLF/Cr⁴⁺:YAG laser with improving beam quality. A wedged laser crystal is employed in the cavity to control the emissions at 1047 nm and 1053 nm independently through the cavity alignment. The pulse energies at 1047 nm and 1053 nm are found to be 19 mJ and 23 mJ, respectively. The peak powers for both wavelengths are higher than 2 MW. Furthermore, the developed Nd:YLF lasers are employed to pump a monolithic optical parametric oscillator for confirming the applicability in nonlinear wavelength conversions. PMID:23389131

  14. Diode-pumped short pulse passively Q-switched 912 nm Nd:GdVO4/Cr:YAG laser at high repetition rate operation

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    A diode-end-pumped passively Q-switched 912 nm Nd:GdVO4/Cr:YAG laser is demonstrated for the first time. In a concave-piano cavity, pulsed 912 nm laser performance is investigated using two kinds of Cr:YAG crystal with different unsaturated transmission ( T U) of 95% and 90% at 912 nm as the saturable absorbers. When the T U = 90% Cr:YAG is used, as much as 2.6 W average output power for short pulsed 912 nm laser is achieved at an absorbed pump power of 34.0 W, corresponding to an optical efficiency of 7.6% and a slope efficiency of 20.3%. Moreover, 10.5 ns duration pulses and up to 2.3 kW peak power is obtained at the repetition rate around 81.6 kHz.

  15. High-repetition-rate single-frequency electro-optic Q-switched Nd:YAG laser with feedback controlled prelase

    NASA Astrophysics Data System (ADS)

    Dai, Shutao; Shi, Fei; Huang, Jianhong; Deng, Jing; Zheng, Hui; Liu, Huagang; Wu, Hongchun; Weng, Wen; Ge, Yan; Li, Jinhui; Lin, Wenxiong

    2015-10-01

    A stable high-repetition-rate, high pulse energy and single-frequency electro-optic Q-switched laser has been developed and demonstrated in this paper. The prelase technique has been used in this single-frequency laser. And a PID feedback control electronics is applied to stabilize the prelase. Meanwhile, a two-plate resonant reflector take the place of traditional dielectric output coupler mirror to enhance the single-axial-mode selection. And a Cr:YAG saturable absorber is also inserted in the cavity to improve single-axial-mode selection. Output laser power over 2 W with 10 ns pulse duration has been obtained at a repetition rate of 1 kHz. And the single-axial-mode probability was 100% in one hour without any manual adjustments. The experimental results show that the prelase technique is reliable to attain single-frequency operation.

  16. Histological Evaluation of Retina after Photo Disruption for Vitreous Humor by Q-Switched Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser

    PubMed Central

    Kameel Ghaly, Sally; Foad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Medhat Abdel-Salam, Ahmed

    2013-01-01

    Introduction: Rabbits’ eyes were exposed to vitreous humor liquefaction with Q - switched (sometimes called “ giant pulses”) Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser using two different energy protocols (5 mJ X 100 pulse and 10 mJ X 50 pulse)with and without vitamin C administration. The histological changes in the retina were investigated to evaluate the protective role of vitamin C. Methods: The rabbits were divided into four main groups (n= 12 each). The first group was divided into three subgroups (n=4) and then treated with 5 mJ X 100 pulse (X means times) delivered to the anterior, middle and posterior vitreous humor respectively. The second group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the first group.The third group was divided into three subgroups (n=4) and then treated with 10 mJ X 50 pulse delivered to the anterior, middle and posterior vitreous respectively. The fourth group received a daily dose of 25 mg/Kg vitamin C for two weeks then was divided into three subgroups and treated with laser in the same manner as the third group. After two weeks, rabbits were decapitated and histological examination for the retina was performed. Results: The results showed that, the anterior vitreous group exposed to 5mJX100 pulse and supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups showed alteration in retina’s tissues histology after laser. Conclusion: Application of Q-switched Nd: YAG laser in vitreous humor liquefaction induces changes in retina’s layers. Although there were some sorts of improvements in retinas supplemented with vitamin C, it cannot protect them against laser oxidative damage. PMID:25606329

  17. An all-fiber high-energy cladding-pumped 93 nanosecond Q-switched fiber laser using an Y 3+-doped fiber saturable absorber

    NASA Astrophysics Data System (ADS)

    Moore, Sean W.; Patterson, Brian D.; Soh, Daniel B.; Bisson, Scott E.

    2014-03-01

    We report an all-fiber passively Q-switched laser using a large mode area (LMA) Yb3+ -doped fiber claddingpumped at 915 nm and an unpumped single-mode (SM) Yb3+-doped fiber as the saturable absorber (SA). The saturable absorber SM fiber and LMA gain fiber were coupled with a fiber taper designed to match the fundamental spatial mode of the LMA fiber and the expanded LP01 mode of the single mode fiber. The amplified spontaneous (ASE) intensity propagating in the single mode SA saturates the absorption before the onset of gain depletion in the pumped fiber, switching the fiber cavity to a high Q-state and producing a pulse. Using this scheme we demonstrate a Q-switched all-fiber oscillator with 32 μJ 93 ns pulses at 1030 nm. The associated peak power is nearly two orders of magnitude larger than that reported in previous experimental studies using a single Yb+3 saturable absorber fiber. The pulse energy was amplified to 0.230 mJ using an Yb3+-doped cladding pumped fiber amplifier fusion spliced to the fiber oscillator, increasing the energy by eight fold while preserving the all-fiber architecture.

  18. Continuous wave and passively Q-switched laser performance of Nd:LuxGd3-xGa5O12 crystal at 1062 nm

    NASA Astrophysics Data System (ADS)

    Fu, X. W.; Jia, Z. T.; Yang, H.; Li, Y. B.; Yuan, D. S.; Zhang, B. T.; Dong, C. M.; He, J. L.; Tao, X. T.

    2012-12-01

    Continuous wave (CW) and passively Q-switched (PQS) laser properties at 1062 nm of the Nd:LuxGd3-xGa5O12 (Nd:LGGG) disordered crystal have been demonstrated. The doping concentrations of Nd3+ and Lu3+ in the as obtained crystal were measured to be 0.96 and 0.66 at.%, respectively. In the CW regime, the output power of 9.73 W was obtained with an optical-to-optical efficiency as high as 60.7% and slope efficiency of 61.2%. During the passively Q-switched operation, the maximum output power of 1.24 W was achieved under the absorbed pump power of 6.86 W. The maximum peak power of 14.20 kW and single pulse energy of 148 μJ were obtained with the Toc = 10% under the absorbed pump power of 6.36 W. The results are much better than those obtained with Nd:LGGG crystal doped with 13.6 at.% Lu3+ and 0.53 at.% Nd3+ ions.

  19. Eye-safe 1.55  μm passively Q-switched Er,Yb:GdAl3(BO3)4 diode-pumped laser.

    PubMed

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

    2016-03-01

    We report for the first time, to the best of our knowledge, on a diode-pumped passively Q-switched Er,Yb:GdAl3(BO3)4 laser. By using a Co2+:MgAl2O4 crystal as a saturable absorber, Q-switched laser pulses with a duration of 12 ns and a maximum energy of 18.7 μJ at a repetition rate of 32 kHz corresponding to an average output power of 0.6 W were obtained at 1550 nm under continuous-wave pumping. In the burst mode of operation, Q-switched laser pulses with the highest energy up to 44 μJ were realized with a pulse repetition rate of 6.5 kHz. PMID:26974080

  20. Diode end-pumped passively Q-switched Tm:YAP laser with 1.85-mJ pulse energy.

    PubMed

    Sebbag, Daniel; Korenfeld, Arik; Ben-Ami, Udi; Elooz, David; Shalom, Eran; Noach, Salman

    2015-04-01

    Passive Q switching of a Tm:YAP solid-state laser at 1935 nm with Cr:ZnSe and Cr:ZnS polycrystalline saturable absorbers is demonstrated for the first time, to the best of our knowledge. With Cr:ZnS, a maximum pulse energy of 1.85 mJ is obtained for a pulse duration of 35.8 ns, resulting in a peak power of 51.7 kW. With Cr:ZnSe, the achieved pulse energy of 1.55 mJ with a pulse duration of 42.2 ns leads to 36.7-kW peak power. These high pulse energies, together with the unique lasing wavelength at 1935 nm, make this laser a promising tool for biomedical and microsurgery applications. PMID:25831305

  1. Black phosphorus: a two-dimension saturable absorption material for mid-infrared Q-switched and mode-locked fiber lasers.

    PubMed

    Li, Jianfeng; Luo, Hongyu; Zhai, Bo; Lu, Rongguo; Guo, Zhinan; Zhang, Han; Liu, Yong

    2016-01-01

    Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted enormous attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). In this paper, the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP. By introducing the same BP SA into two specifically designed rare earth ions doped fluoride fiber lasers at mid-infrared wavebands, Q-switching with the pulse energy of 4.93 μJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The operation wavelength of ~2970 nm for generated pulse is the reported longest wavelength for BP SA based fiber lasers. PMID:27457338

  2. Gold nanorods as the saturable absorber for a diode-pumped nanosecond Q-switched 2  μm solid-state laser.

    PubMed

    Huang, Haitao; Li, Min; Liu, Pian; Jin, Lin; Wang, Hui; Shen, Deyuan

    2016-06-15

    Gold nanorods (GNRs) with an average aspect ratio of 15 were experimentally exploited as the 2 μm saturable absorber in a laser diode pumped Tm:YAG laser for the first time, to the best of our knowledge. Q-switched pulses with a maximum average output power of 380 mW, a minimum pulse width of 796 ns, and a pulse repetition rate of 77 kHz were achieved under the LD pump power of 6.2 W. Our results indicate that GNRs with a large aspect ratio are promising saturable absorbers in the 2 μm wavelength region. PMID:27304267

  3. Fractional 532-nm Q-switched Nd:YAG laser: One of the safest novel treatment modality to treat café-au-lait macules.

    PubMed

    Won, Kwang Hee; Lee, Ye Jin; Rhee, Do Young; Chang, Sung Eun

    2016-10-01

    Café-au-lait macules (CALMs) are benign epidermal basilar hyperpigmentations that can be found in an isolated form or in association with neurocutaneous syndromes. Frequency-doubled Q-switched neodymium-doped yttrium aluminum garnet laser (532-nm QSNYL) does not penetrate deeply into the skin and is therefore suitable for epidermal pigmented lesion. Fractional photothermolysis (FP) targets only very small areas of the skin, without injuring adjacent areas of healthy, normal skin. Herein, we report a case of CALMs successfully treated with fractional 532-nm QSNYL. By applying FP to 532-nm QSNYL, we could treat CALMs safely with less downtime as compared to conventional laser treatments and expect more energy delivery for each microscopic hole, thereby allowing higher response rate. PMID:26962881

  4. Black phosphorus: a two-dimension saturable absorption material for mid-infrared Q-switched and mode-locked fiber lasers

    PubMed Central

    Li, Jianfeng; Luo, Hongyu; Zhai, Bo; Lu, Rongguo; Guo, Zhinan; Zhang, Han; Liu, Yong

    2016-01-01

    Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted enormous attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). In this paper, the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP. By introducing the same BP SA into two specifically designed rare earth ions doped fluoride fiber lasers at mid-infrared wavebands, Q-switching with the pulse energy of 4.93 μJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The operation wavelength of ~2970 nm for generated pulse is the reported longest wavelength for BP SA based fiber lasers. PMID:27457338

  5. Passively Q-switched mode locking in a compact Nd:GdVO4/Cr:YAG self-Raman laser

    NASA Astrophysics Data System (ADS)

    Peng, Jiying; Zheng, Yi; Zheng, Kai; Chang, Xiaowei

    2012-11-01

    Passively Q-switched mode locking in a compact Nd:GdVO4 self-Raman laser with a Cr:YAG saturable absorber was demonstrated. The picosecond first stokes at 1173 nm was successfully obtained. When the optical cavity length changed from 167 mm to 120 mm, the mode-locked pulse repetition rate increased from 0.9 GHz to 1.25 GHz. At the maximum diode pump power of 10 W and with a pulse repetition rate of 0.9 GHz, an average output power up to 105 mW has been achieved at 1173 nm. In addition, the yellow laser output at 586.5 nm was also realized by frequency doubling with an LBO crystal.

  6. 32.5 mJ and 4.6 ns 532 nm Q-switched Nd:YAG laser at 500 Hz.

    PubMed

    Zhang, Zilong; Liu, Qiang; Gong, Mali

    2013-04-20

    A laser diode side-pumped electro-optical Q-switched Nd:YAG green light laser with high repetition rates, short pulse width, and high peak power was demonstrated. We studied the performance of the oscillator at the repetition rates from 100 to 500 Hz. At 500 Hz, 61 mJ, 5 ns of 1064 nm infrared light pulses were obtained with an oscillator-amplifier system. The peak power of the pulse was 12 MW. By frequency doubling with a LiB(3)O(5)(LBO) crystal, 32.5 mJ, 4.6 ns of 532 nm green light was achieved, corresponding to a peak power of 7 MW. The frequency conversion efficiency was 53.3%. PMID:23669684

  7. Diode-end-pumped, electro-optically Q-switched Nd:YVO4 slab laser and its second-harmonic generation.

    PubMed

    Zhang, Hengli; Shi, Peng; Li, Daijun; Du, Keming

    2003-03-20

    We describe the operation of a near-diffraction-limited, 1,064-nm electro-optically Q-switched Nd:YVO4 slab laser that is end pumped by laser-diode stacks and its efficient second-harmonic generation by using a lithium triborate (LBO) crystal. The energy per pulse of 3.6 and 0.8 mJ and pulse widths of 5 and 13.5 ns were obtained at repetition of 5 and 40 kHz, respectively. With a LBO crystal, a maximum output power of 15.6 W at 532 nm was obtained at the repetition rate of 40 kHz, the corresponding conversion efficiency was 60%, and the pulse width was 11.3 ns. At 10 kHz, the pulse energy of 532 nm was 1.2 mJ, and the pulse width was 5 ns. PMID:12665098

  8. 10 W mid-IR optical parametric oscillator pumped by a passively Q-switched Ho:YAG ceramic laser

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    We report on a ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumped by a Cr2+:ZnS saturable absorbed passively Q-switched (PQS) Ho:YAG ceramic laser. The maximum output power of the ZGP OPO was 10 W at a 27.4 W incident PQS Ho:YAG ceramic laser, corresponding to a slope efficiency of 41.3% with respect to the incident pump power. The minimum mid-IR pulse width of 21 ns in 3.8 and 4.6 μm was obtained from the ZGP OPO. The beam quality was measured to be M 2  <  3.22.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Black phosphorus: a two-dimension saturable absorption material for mid-infrared Q-switched and mode-locked fiber lasers

    NASA Astrophysics Data System (ADS)

    Li, Jianfeng; Luo, Hongyu; Zhai, Bo; Lu, Rongguo; Guo, Zhinan; Zhang, Han; Liu, Yong

    2016-07-01

    Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted enormous attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). In this paper, the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP. By introducing the same BP SA into two specifically designed rare earth ions doped fluoride fiber lasers at mid-infrared wavebands, Q-switching with the pulse energy of 4.93 μJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The operation wavelength of ~2970 nm for generated pulse is the reported longest wavelength for BP SA based fiber lasers.

  11. Diode end-pumped high-power Q-switched double Nd:YAG slab laser and its efficient near-field second-harmonic generation.

    PubMed

    Zhu, Peng; Li, Daijun; Qi, Bingsong; Schell, Alexander; Shi, Peng; Haas, Claus; Fu, Shaojun; Wu, Nianle; Du, Keming

    2008-10-01

    We reported on an all-solid-state double Nd:YAG slab laser. The laser was based on two diode end-pumped Nd:YAG slabs and a stable-unstable hybrid resonator. A cw output of 189 W and an average Q-switched output of 169 W at 10 kHz with an M(2) factor of 1.5 in the slow direction and 1.7 in the fast direction were obtained. We demonstrated efficient near-field frequency doubling by imaging the one-dimensional top-hat near-field to a lithium triborate frequency doubler. We obtained 93 W green light at 10 kHz with a pulse width of 10.7 ns. The efficiency of second-harmonic generation was up to 57%. PMID:18830367

  12. The GTR-KTP intracavity optical parametric oscillator driven by a diode-end-pumped acousto-optical Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Huang, H. T.; Zhang, B. T.; He, J. L.

    2013-03-01

    An efficient eye-safe gray-trace resistance-KTP (GTR-KTP) intracavity optical parametric oscillator (IOPO) excited by a diode-end-pumped Q-switched Nd:YAG laser was demonstrated. Under a laser diode power of 11.4 W, a maximum average output power of 1.2 W at 1572 nm was obtained at a repetition rate of 15 kHz, corresponding to a diode-to-signal conversion efficiency of 10.5%. As for the common KTP IOPO under the same pump conditions and cavity design, a lower average output power of 0.96 W was obtained. Consequently, the corresponding GTR-KTP OPO conversion efficiency was increased by 25% compared with that obtained in common KTP IOPO.

  13. Photoacoustic-induced vascular tissue dissection resulting from irradition with a Q-switched frequency-doubled Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Flock, Stephen T.; Ferguson, Scott; Thomas, Stuart; Schwager, Konrad A.; Waner, Milton

    1995-05-01

    A Q-switched frequency-doubled Nd:YAG dye laser, tuned to 577 nm, was used to study the effect of nanosecond pulsed light on vascular tissue. Different reactions such as vasospasm, vessel expansion and vessel rupture were observed in living rats and were seen to be correlated with increasing fluence up to 3 J/cm2. When it occurred, localized vessel rupture was seen on the irradiated side of the blood vessel, as well as on the opposite side. It was hypothesized that the damage on the backside of the blood vessel is the result of intense acoustic waves produced by strong absorption of the laser radiant energy in the first 30 micrometers of blood. Experiments were performed in vitro using cuvettes filled with diluted hemoglobin on which the 532 nm radiant energy produced by a Q-switched frequency-doubled Nd:YAG laser impinged. High-speed imaging of the irradiated air-blood interface using a time-delayed pulsed nitrogen-dye laser did not show evidence of cavitation micro-bubbles but did show the formation of a large, slowly expanding vapor bubble. Measurements of the acoustic waves produced with 12 mJ pulse in a spot size estimated to be 0.25 mm gave pressures up to 74 bars. Measurements at different positions with respect to the irradiation spot showed differences in acoustic amplitude that could not be explained by absorption attenuation. It is hypothesized that these differences are a result of differential diffraction of the frequency components of the acoustic wave, components of which extend up to a maximum of about 4 MHz. It is the highly directional high frequency acoustic energy that could be causing the damage on the side of the blood vessel opposite the point of irradiation.

  14. 50-kHz, 50-ns UV pulse generation by diode-pumped frequency doubling Pr3+:YLF Q-switch laser with a Cr4+:YAG saturable absorber.

    PubMed

    Tanaka, Hiroki; Kariyama, Ryosuke; Iijima, Kodai; Kannari, Fumihiko

    2016-08-10

    We demonstrate intracavity second-harmonic generation at 320 nm of a diode-pumped praseodymium-doped YLF laser Q-switched by a Cr4+:YAG crystal. By employing two 3.5-W high-power blue InGaN diode lasers as the pump source, we obtained 50-ns Q-switched pulses with a pulse energy of 1.54 μJ at a repetition rate of 50 kHz. A rate equation analysis shows good agreement with the experimental results. PMID:27534459

  15. Highest-speed dicing of thin silicon wafers with nanosecond-pulse 355nm q-switched laser source using line-focus fluence optimization technique

    NASA Astrophysics Data System (ADS)

    Bovatsek, James M.; Patel, Rajesh S.

    2010-02-01

    Due to current and future anticipated widespread use of thin silicon wafers in the microelectronics industry, there is a large and growing interest in laser-based wafer dicing solutions. As the wafers become thinner, the laser advantage over saw dicing increases in terms of both the speed and yield of the process. Furthermore, managing the laser heat input during the dicing process becomes more important with increasingly thin wafers and with increasingly narrow saw streets. In this work, shaped-beam laser-cutting of thin (100 μm and below) silicon is explored with Newport / Spectra- Physics Pulseo 20-W nanosecond-pulse 355-nm DPSS q-switched laser system. Optimal process conditions for cutting various depths in silicon are determined, with particular emphasis on fluence optimization for a narrow-kerf cutting process. By shaping the laser beam into a line focus, the optimal fluence for machining the silicon can be achieved while at the same time utilizing the full output power of the laser source. In addition, by adjusting the length of the laser line focus, the absolute fastest speed for various cutting depths is realized. Compared to a circular beam, a dramatic improvement in process efficiency is observed.

  16. Evaluation of a commercially available passively Q-switched Nd:YAG laser with LiF:F-2 saturable absorber for laser-induced breakdown spectroscopy

    SciTech Connect

    Carson, Cantwell; Goueguel, Christian; Sanghapi, Herve; Jinesh, Jain; McIntyre, Dustin

    2015-12-11

    Interest in passively Q-switched microchip lasers as a means for miniaturization of laser-induced breakdown spectroscopy (LIBS) apparatus has rapidly grown in the last years. To explore the possibility of using a comparatively UV–vis transparent absorber, we herein present the first report on the evaluation of a commercially available flash lamp-pumped passively Q-switched Nd:YAG laser with LiF: saturable absorber as an excitation source in LIBS. Quantitative measurements of barium, strontium, rubidium and lithium in granite, rhyolite, basalt and syenite whole-rock glass samples were performed. Using a gated intensified benchtop spectrometer, limits of detection of 0.97, 23, 37, and 144 ppm were obtained for Li, Sr, Rb, and Ba, respectively. Finally, we discuss the advantages of using such a laser unit for LIBS applications in terms of ablation efficiency, analytical performances, output energy, and standoff capabilities.

  17. Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

    PubMed Central

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

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

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

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

    PubMed

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

    2015-07-27

    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. PMID:26367663

  20. Compact KTA-based intracavity optical parametric oscillator driven by a passively Q-switched Nd:GdVO4 laser.

    PubMed

    Miao, Jieguang; Peng, Jiying; Wang, Baoshan; Tan, Huiming

    2008-08-10

    We present a compact and efficient KTA-based intracavity optical parametric oscillator (IOPO) driven by a diode-end-pumped Nd:GdVO(4)/Cr:YAG passively Q-switched laser. At the incident diode pump power of 9.2 W, signal (1.53 microm) and idler (3.47 microm) average output powers of up to 744 and 356 mW, respectively, have been obtained. The total (signal+idler) optical-to-optical conversion efficiency is as high as 12%. By using the knife-edge method, near-diffraction-limited signal and idler beams have been detected, and the M(2) factors are well within 1.2. In addition, based on the ABCD matrix theory, the impact of mode matching and the thermal lens effect on the OPO output have been analyzed. PMID:18690272

  1. Isolas of periodic passive Q-switching self-pulsations in the three-level:two-level model for a laser with a saturable absorber.

    PubMed

    Doedel, Eusebius J; Pando, Carlos L L

    2011-11-01

    We show that a fundamental feature of the three-level:two-level model, used to describe molecular monomode lasers with a saturable absorber, is the existence of isolas of periodic passive Q-switching (PQS) self-pulsations. A common feature of these closed families of periodic solutions is that they contain regions of stability of the PQS self-pulsation bordered by period-doubling and fold bifurcations, when the control parameter is either the incoherent external pump or the cavity frequency detuning. These findings unveil the fundamental solution structure that is at the origin of the phenomenon known as "period-adding cascades" in our system. Using numerical continuation techniques we determine these isolas systematically, as well as the changes they undergo as secondary parameters are varied. PMID:22181484

  2. Second Stokes 1129 nm generation in gray-trace resistance KTP intracavity driven by a diode-pumped Q-switched Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Huang, H.-T.; He, J.-L.; Wang, Y.

    2011-03-01

    A gray-trace resistance KTP (GTR-KTP) second Stokes Raman laser intracavity driven by a diode-pumped acousto-optic Q-switched Nd:YVO4 laser was first demonstrated in this paper. With an incident pump power of 9.5 W, the intracavity GTR-KTP Raman laser, operating at the repetition rate of 20 kHz, produced the maximum average output power of 860 mW at 1129 nm. The minimum pulse width obtained in this GTR-KTP Raman laser was 10.8 ns. When the GTR-KTP was substituted with a common KTP, a lower average output power of 720 mW and longer pulse width of 15.9 ns were obtained in the common KTP Raman laser under the same pump condition and cavity setup as the GTR-KTP Raman laser. Experimental results indicated that the decreased absorption at the fundamental and Stokes wave in GTR-KTP was beneficial to improve the stimulated Raman scattering performance.

  3. Room temperature operation of 2.67 mJ pulse LD end pumped Q-switched Tm:YAG laser

    NASA Astrophysics Data System (ADS)

    Song, Xuedi; Wu, Chunting; Chen, Xinyu; Yu, Kai; Jin, Guangyong

    2014-12-01

    Due to 2 μm band in the absorption of water and CO2, the diode pumped solid state lasers with wavelength around 2 μm have important applications in laser medicine and remote sensing, such as it can be used as a scalpe or a light source of Coherent Doppler Wind Lidar and Differential Absorption Lidar. In the recently years, scientists have done much work on the development of such lasers. There're many reports on continuous Tm:YAG laser. However, the study on Q-switched Tm:YAG laser, which is more useful in applications, was very rare. As the light source of Coherent Doppler Wind Lidar, large energy and wide pulse width is desired. Current reports mostly adopted CW pumped source, but it would make a mount of heat. Pulse pumping method could reduce the heat accumulation and improve the heat stability of the laser. How to improve the single pulse energy was the focus of current study. In this paper, a single end bonding Tm:YAG crystal with Tm3+ doping concentration of 3.5at.% was used. Acousto-optic (AO) Q-switched (GOOCH and HOUSEGO QS041-10M-HI8) operation was adopted in our experiment. In the repetition frequency of 100Hz, a maximum single energy of 2.67 mJ (measured by Ophir 30A-BB) and the narrowest pulse width of 149 ns (measured by Vigo PCI-3TE-12 detector) were achieved at room temperature. The M2x was 1.31 and the M2y was 1.35 (measured by Spiricon Pyrocam-III). Tm:YAG laser was developed by using a pulse diode pumped L shape resonant cavity. The transmittance of the curve output mirror was 4% and the curvature radius of which was 300 mm. The output center wavelength of the laser was measured to be 2013.5 nm (measured by YOKOGAWA AQ6375).

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

    PubMed

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

    2009-08-01

    We present a simple technique to integrate an electro-optic Q switch in a periodically poled bulk lithium niobate crystal bounded by two unpoled (monodomain) regions. The technique exploits the high sensitivity to low applied electric fields of the total internal reflection condition in the periodic poled-unpoled boundary for the small grazing incidence angles associated with the diffraction of a focused Gaussian beam that propagates in the periodically poled region with its axis parallel to the boundary. When the arrangement is placed intracavity to a 1064 nm diode-pumped Nd(3+):YVO(4) laser, it performs simultaneously as a Q switch and as a second-harmonic generator, with Q switching starting at applied voltages as low as 1 V over a 500 microm thickness and with no additional optical elements. PMID:19649073

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Li, Deyong; Li, Yunliang; Li, Hao; Weng, Yuxiang; Wu, Xianyou; Yu, Qingxu

    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.

  7. Short pulse width UV laser at 355 nm based on pulse LD side-pumped ceramic Nd:YAG and BBO electro-optical Q-switched

    NASA Astrophysics Data System (ADS)

    Bai, Y.; Chen, X. M.; Lu, B. L.; Ren, Z. Y.; Bai, J. T.

    2012-02-01

    355 nm UV laser was obtained with a pulse width of less than 5 ns and a peak power at megawatt level by adopting the 808 nm pulse laser diode (LD) side-pumped ceramic Nd:YAG and BBO crystal electrooptical Q-switched. The single-pulse energy was measured to be 24.3 mJ with 4.86 ns pulse width and 5.11 MW peak power at a repetition rate of 1Hz under a 120 A pump current. Using a volume of beam splitting mirrors, wavelength outputs at 1064, 532, and 355 nm pulse laser was obtained simultaneously with a respective average output power of 656.6, 357.1, and 260.5 mW, the beam quality factor M 2 are ( M {/x - 1064 2} = 5.83, M {/y - 1064 2} = 5.61), ( M {/x - 532 2} = 4.25, M {/y - 532 2} = 4.08) and ( M {/x - 355 2} = 6.32, M {/y - 355 2} = 6.15), corresponding to a conversion efficiency at 11% from 1064 to 355 nm.

  8. A 2 μm continuous wave and passively Q-switched fiber laser in thulium-doped germanate glass fibers

    NASA Astrophysics Data System (ADS)

    Fan, Xiaokang; Kuan, Peiwen; Li, Kefeng; Zhang, Lei; Li, Wentao; Hu, Lili

    2014-08-01

    In this study, we designed and fabricated a Tm3+-doped germanate glass fiber by using a rod-in-tube technique. The fiber has a core diameter of ~13.5 μm with a cladding of 125 μm. The Tm3+ doping concentration reached ~13 500 ppm, and the propagation loss of the fiber was less than 0.03 dB cm - 1 at 1310 nm. Pumping with a 1590 nm fiber laser constructed in-house, a 44.7 mW continuous-wave fiber laser at 1940 nm was achieved in a 22 cm-long germanate fiber, with a slope efficiency of 26%. The passively Q-switched pulse output was first demonstrated by using a carbon nanotube saturable absorber in the germanate fiber. The germanate fiber laser generates approximately 1.5 μs pulses with a maximum pulse energy of 110 nJ, and the repetition rate varies from 15 to 84 kHz, depending on pump power.

  9. Multi-wavelength passively Q-switched c-cut Nd:YVO4 self-Raman laser with Cr4+:YAG saturable absorber

    NASA Astrophysics Data System (ADS)

    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.

  10. Highly efficient 2  μm CW and Q-switched Tm3+:Lu2O3 ceramics lasers in-band pumped by a Raman-shifted erbium fiber laser at 1670  nm.

    PubMed

    Antipov, Oleg; Novikov, Anton; Larin, Sergey; Obronov, Ivan

    2016-05-15

    Highly efficient laser oscillations at 2 μm were investigated in Tm:Lu2O3 ceramics in-band pumped at 1670 nm by a Raman-shifted erbium fiber laser. Both 23 W CW and 15 W active Q-switched oscillations with 40 ns pulse duration and 15-30 kHz repetition rate were achieved in a high-quality beam. The evolution of two generated waves at 1966 and 2064 nm in dependence on pump power was studied. PMID:27176987

  11. Multi-wavelength Q-switched Erbium-doped fiber laser with photonic crystal fiber and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cheak Tiu, Zian; Ahmad, Fauzan; Tan, Sin Jin; Zarei, Arman; Ahmad, Harith; Wadi Harun, Sulaiman

    2014-08-01

    A simple multi-wavelength passively Q-switched Erbium-doped fiber laser (EDFL) is demonstrated using low-cost multi-walled carbon nanotubes (MWCNTs)-based saturable absorber, which is prepared using polyvinyl alcohol as a host polymer. The multi-wavelength operation is achieved based on non-linear polarization rotation effect by incorporating 50 m long photonic crystal fiber in the ring cavity. The EDFL produces a stable multi-wavelength comb spectrum for more than 14 lines with a fixed spacing of 0.48 nm. The laser also demonstrates a stable pulse train with the repetition rate increasing from 14.9 to 25.4 kHz as the pump power increases from the threshold power of 69.0 mW to the maximum pump power of 133.8 mW. The minimum pulse width of 4.4 μs was obtained at the maximum pump power of 133.8 mW while the highest energy of 0.74 nJ was obtained at the pump power of 69.0 mW.

  12. Optical triggering of a Q-switched Nd:YAG laser via transverse bleaching of a Cr:YAG saturable absorber.

    PubMed

    Cole, Brian; Lei, Jonathan; DiLazaro, Tom; Schilling, Bradley; Goldberg, Lew

    2009-11-01

    Optical triggering via direct bleaching of a Cr:YAG saturable absorber was applied to a monolithic Nd:YAG/Cr:YAG laser crystal. The method uses a single laser diode bar to bleach a thin sheet within the saturable absorber from a direction orthogonal to the lasing axis. By placing the Q-switch at the time corresponding to the steepest slope (dT/dt) for change in transmission during bleaching, the pulse-to-pulse timing jitter showed a 13.2x reduction in standard deviation, from 132 ns for free-running operation to 10 ns with optical triggering. We measured that a fluence of 60 kW/cm(2) was sufficient to enable optical triggering, where a diode appropriately sized for the length of the Cr:YAG (approximately 3 mm) would then require only approximately 150 W of optical power over a 1-2 micros duration to enable effective jitter reduction. Additionally, we measured an increase in optical-to-optical efficiency with optical triggering, where the efficiency improved from 12% to 13.5%. PMID:19881668

  13. High-power multichannel PPMgLN-based optical parametric oscillator pumped by a master oscillation power amplification-structured Q-switched fiber laser.

    PubMed

    Chen, Tao; Wei, Kaihua; Jiang, Peipei; Wu, Bo; Shen, Yonghang

    2012-10-01

    We experimentally demonstrated a compact fiber laser-pumped multichannel PPMgLN-based optical parametric oscillator (OPO) generating total OPO output power of 15.8, 15.2, 14.2, 12.9, and 8.8 W with idler output power of 4.7, 4.3, 4.1, 3.3, and 2.1 W at the wavelength of 3.43, 3.63, 3.72, 3.83, and 3.99 μm, respectively. The OPO was pumped by a fully fiberized polarization maintaining (PM) ytterbium-doped pulsed fiber master oscillation power amplifier (MOPA) operating at 1064 nm at a repetition rate of 65 kHz with effective pump power of 28.7 W. The MOPA system was constructed with an acousto-optic Q-switched fiber laser seed and only one stage PM fiber amplifier without any free space components, which makes the pump system compact and stable in the long-term. Comparisons on efficiencies and signal wavelength shifts between different channels showed that the idler absorption was the main factor preventing high average-power OPO operation with long idler wavelength. PMID:23033106

  14. A Retrospective Study on the Characteristics of Treating Nevus of Ota by 1064-nm Q-switched Neodymium-doped Yttrium Aluminum Garnet Laser

    PubMed Central

    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 < 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. PMID:27293272

  15. Efficacy of 694-nm fractional Q-switched ruby laser (QSRL) combined with sonophoresis on levorotatory vitamin C for treatment of melasma in Chinese patients.

    PubMed

    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. PMID:27126411

  16. Highly efficient tunable mid-infrared optical parametric oscillator pumped by a wavelength locked, Q-switched Er:YAG laser.

    PubMed

    Liu, Jun; Tang, Pinghua; Chen, Yu; Zhao, Chujun; Shen, Deyuan; Wen, Shuangchun; Fan, Dianyuan

    2015-08-10

    A highly efficient and stable mid-infrared optical parametric oscillator is demonstrated, pumped by an electro-optic Q-switched Er:YAG laser with operating wavelength locked at 1645 nm by a volume Bragg grating. The oscillator, based on MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal, yields a maximum overall average output power in excess of 1 W, corresponding to a conversion efficiency of 35.5% and a slope efficiency of 43.6%. The signal and idler wavelengths of the OPO are around ~2.7 μm and ~4.3 μm, respectively, corresponding to the two peak absorption bands of CO(2). Lasing characteristics of the oscillator, including the time evolution of the pump, signal and idler pulses at different pump power levels, are also investigated. Temperature tuning of the MgO:PPLN crystal gives signal and idler ranges of 2.67 to 2.72 μm and 4.17 to 4.31 μm, respectively. PMID:26367934

  17. Optical parametric oscillator of mid-IR, visible and UV ranges with synchronous pumping by a Q-switched mode-locked Nd : YAG laser

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    The parametric generation in a nonlinear PPLN crystal synchronously pumped by a Q-switched mode-locked Nd : YAG laser with a pulse duration of 45 ps is studied. The output pump intensity in the nonlinear crystal reaches ~10 GW cm-2. At a pulse repetition rate of 1 kHz, the average output power at the idler wavelength (~3.6 μm) is ~12 mW, the peak power is ~25 kW, and the conversion efficiency (with respect to the absorbed power) is ~10%. The radiation linewidth at the signal wavelength (~1.5 μm) is 13 cm-1. Along with the signal and idler waves, the output emission spectrum contains lines at wavelengths of 822, 754, 624, 532, 463, 442, 392 and 355 nm. The tunable radiation with wavelengths in the vicinity of 392, 463 and 822 nm is observed for the first time. The tuning ranges for the new lines are measured (5 – 10 nm) and their origin is explained.

  18. A preliminary comparison of the transient effects of single versus multiple q-switched doubled-neodymium laser pulses

    NASA Astrophysics Data System (ADS)

    Previc, Fred H.

    1987-09-01

    A comparison between the effects of single and multiple laser pulse-trains of equivalent energy was performed. Visual evoked potentials (VEPS) recorded bipolarly from the visual cortex of two rhesus monkeys in response to a counterphasing grating were used to assess the magnitude of the visual loss following four types of exposures: single and multiple pulses with total energies equal to 50 and 500 percent of the maximum permissible exposure (MPE) standard for humans. The results showed that the effects of a series of laser flashes presented within 200 ms are similar to those of a single laser flash whose energy is equivalent to the cumulative energy of the multiple-pulse exposure.

  19. Integrated-optical q-switching and mode-locking of a Nd3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Geister, G.

    1990-07-01

    RareEarth doped silica fibers are interesting light sources for optical communications and sensor applications. Their broad fluorescence linewidth and the long spontaneous lifetime of the upper laser level otter the possibility to produce short and intense light pulses. We demonstrate pulsed operation of a Nddoped fiber laser with an asymmetric switched directional coupler operating as an intracavity intensity . modulator. 1 . Fiberlaser configuration The fiberlaser arrangement is shown in Fig. 1 . The prepared modulator is an xcut LiNbO3substrate with a pair of indiffused Tistripe waveguides of 5 pm width which are singlemode at the lasing wavelength A 1088 nm. The minimum waveguide separation is 2 im and has 8 mm length. One single pair of 8 mm long Alelectrodes with a 10 pm gap deposited onto the substrate surface is placed asymmetrically relative to the waveguides. This electrode arrangement provides electrooptic modulation of the phase mismatch between the two waveguides via the strong electrooptic coefficient rss of the LiNbO3 crystal. The modulator chip is Lw 20 mm long. The singlemode Ndfiber with LF 3. 485 m is pumped at a wavelength A 825 nm and butt coupled to the modulator. At the buttjoint the faces are angledcut with angles Yr 1 1. and yp. 7. 5 so no residual cavities exist within the laser resonator. The laser cavity is defined by dielectric coatings on the free ends of

  20. High-energy passively Q-switched operation of Yb:GdCa(4)O(BO(3))(3) laser with a GaAs semiconductor saturable absorber.

    PubMed

    Chen, Xiaowen; Wang, Lisha; Han, Wenjuan; Guo, Yunfeng; Xu, Honghao; Yu, Haohai; Zhang, Huaijin; Liu, Junhai

    2015-11-16

    High-energy passively Q-switched operation of a Yb:GdCa(4)O(BO(3))(3) laser is demonstrated, with a GaAs crystal plate acting as saturable absorber. An average output power of 1.31 W at 1027 nm is produced at a pulse repetition rate of 1.92 kHz, the resulting pulse energy, duration, and peak power being respectively 0.68 mJ, 9.0 ns, and 75.6 kW. The shortest pulse duration obtained is 4.9 ns; whereas the maximum pulse energy achievable amounts to 0.83 mJ, which proves to be nearly one order of magnitude higher than ever generated from Yb or Nd lasers passively Q-switched by a GaAs saturable absorber. PMID:26698515

  1. Compact and efficient passively Q-switched laser at 473  nm with an Nd:YAG/YAG/Cr4+:YAG/YAG multifunctional composite crystal.

    PubMed

    Zhu, Siqi; Zhou, Haiqiong; Jiang, Wei; Li, Zhen; Yin, Hao; Zhang, Ge; Chen, Zhenqiang

    2016-05-20

    An Nd:YAG/YAG/Cr4+:YAG/YAG composite crystal and an LBO crystal were used to generate a passively Q-switched frequency-doubling 473 nm blue laser for the first time, to the best of our knowledge. The result demonstrated that the slope efficiency of this system reaches 18%, which is the highest in all the passively Q-switched 473 nm laser systems reported, to the best of our knowledge. Under the pumped power of 8.64 W, the maximum average output power of 0.93 W was obtained with a pulsewidth of 78 ns, and the repetition rate of 18.5 kHz. PMID:27411146

  2. Combination treatment of low-fluence Q-switched Nd:YAG laser and oral tranexamic acid for post-inflammatory hyperpigmentation due to allergic contact dermatitis to henna hair dye.

    PubMed

    Lee, Young Bok; Park, Sae Mi; Kim, Jin-Wou; Yu, Dong Soo

    2016-04-01

    A 64-year-old female presented with facial hyperpigmentation. She had dyed her hair monthly with pure henna powder for the past seven months. After patch tests, the patient was diagnosed as post-inflammatory hyperpigmentastion due to allergic contact dermatitis to pure henna that has rarely been reported. The patient underwent Q-switched Nd:YAG laser treatment and was treated with oral tranexamic acid for 10 weeks. The hyperpigmentation on her forehead demonstrated substantial improvement. PMID:26734817

  3. Stable kilo-hertz electro-optically Q-switched Tm,Ho:YAP laser at room temperature

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2011-01-01

    Background and aims: Enlarged facial pores remain one of the major cosmetic concerns among Asian females. This study attempted to assess and compare the efficacy of a combination of the Q-switched and quasi long-pulsed (micropulsed) Nd:YAG laser to reduce the size of the enlarged pores with and without an exogenous photoenhancer. Methods: In twenty five female subjects mean age 34.04 yr and skin type II-IV, a carbon lotion as a photoenhancer was applied on one side of the face (Method 1) and the other side was used as the control (Method 2). The entire face was then treated with a single pass of the 1064 nm Nd:YAG laser in the micropulsed mode, pulse fluence and width of 2.3 J/cm2 and 300 µsec, respectively. Multiple passes were then delivered in the Q-switched mode (2.5 J/cm2 and 5 nsec). Results: Three weeks after the final treatment, 75% of the subjects showed improvement with method 1 whereas 67% showed improvement with method 2. No adverse side effects were reported with either method. Conclusions: Although histological confirmation was not performed, we were able to prove both subjectively and objectively that the use of the combination of the micropulsed and Q-switched modes of the Nd:YAG laser was useful in reducing pore size, and that the photoenhancer improved the efficacy. PMID:24155527

  5. Selective photothermolysis of cutaneous pigmentation by Q-switched Nd: YAG laser pulses at 1064, 532, and 355 nm

    SciTech Connect

    Anderson, R.R.; Margolis, R.J.; Watenabe, S.; Flotte, T.; Hruza, G.J.; Dover, J.S.

    1989-07-01

    Exposure of skin to nanosecond-domain laser pulses affects the pigmentary system by a process called selective photothermolysis, in which melanosomes and pigmented cells are preferentially altered. Due to the broad absorption spectrum of melanin, this effect may occur with wavelengths that penetrate to vastly different depths within tissue, potentially producing different biologic responses. The effects of single near-ultraviolet (355 nm), visible (532 nm), and near infrared (1064 nm) pulses of 10-12 nsec duration were determined in guinea pig skin using gross, histologic, and electron microscopic observations. Threshold response in pigmented skin was a transient immediate ash-white discoloration, requiring 0.11, 0.20, and 1.0 J/cm2, at 355, 532, and 1064 nm, respectively. At each wavelength, melanosomes were ruptured within keratinocytes and melanocytes, with cytoplasmic and nuclear alterations. Delayed epidermal depigmentation occurred, followed by gradual repigmentation. Deep follicular cells were altered only at 532 and 1064 nm, which produced permanent leukotrichia. The action spectrum for threshold response was consistent with mechanisms implied by selective photothermolysis. These data may be useful for consideration of treatment for cutaneous pigmentation abnormalities or unwanted follicular pigmentation, or both.

  6. Experimental and theoretical study of a laser-diode-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber.

    PubMed

    Xu, Chao; Li, Guiqiu; Zhao, Shengzhi; Li, Xin; Du, Guolong; Yin, Lei

    2011-09-10

    A laser-diode-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber is realized in a V-type resonator. The dependences of the pulse repetition rate, pulse width, single-pulse energy, and peak power on the incident pump power are measured and contrasted. By assuming the intracavity photon density and the initial population-inversion density to be Gaussian spatial distributions, the space-dependent rate equations of this laser are given. The numerical solutions of the rate equations are consistent with the experimental results. In order to optimize the described system, the variations of the pulse width, peak power, single-pulse energy, and laser efficiency with the initial transmission of the saturable absorber and the ratio of the laser beam radius to the pump beam radius are also calculated, respectively. PMID:21946991

  7. Treatment of lichen pilaris with a Q-switched Nd:YAG laser in quasi long-pulsed mode: A case report (a secondary publication)

    PubMed Central

    2014-01-01

    Background and Aims: Lichen pilaris is a very common disease typically seen among young adults on their upper arms as a manifestation of hyperkeratotic lesions occurring in the pores. Only a few treatments have been reported as significantly effective, so often natural resolution over time is the only option. The present study examined the use of a 1064 nm Q-switched Nd:YAG laser (QSNY) in quasi long-pulsed mode, in an attempt to treat a case of lichen pilaris. Subject and Methods: A 33-year-old male presented with light-brown aggregated papules observed on both sides of the upper arms. The affected areas were treated every other week (QSNY, pulse width 300 µs, pulse energy 3.0 J/cm2, spot size 6 mm and repetition rate 10 Hz). Clinical photography was taken of the lesions at baseline and three months after the final treatment in addition to macrophotography and 3-D photography, biopsies being taken at both time points for histological comparison. Results: The clinical photography and objective image evaluation demonstrated shrinkage of pores and improvement of the unevenness of the skin. Histological examination suggested that the effect of the micropulsed QSNY on the horny layer, epidermal keratinocytes and dermal collagen resulted in a peeling effect and increased dermal collagen density, which eventually led to the shrinkage of the pores and improvement of the skin condition. Conclusions: The results of this single patient case report suggest that the micropulsed QSNY could be an effective treatment option for lichen pilaris, improvement of which is often difficult. Further studies with an appropriately-sized population are merited to confirm these preliminary results. PMID:25368447

  8. Large repetitively Q-switched oscillators

    NASA Astrophysics Data System (ADS)

    Epstein, H. M.; Dulaney, J. L.; O'Loughlin, J. F.; Altman, W. P.

    A versatile waveform laser which can operate in bursts from 5 to 160 ms long and deliver up to 30 kJ power burst has been constructed. This Nd:glass laser system consists of four oscillators in parallel. Each oscillator can be varied in length from about 3 to 10 m, and contains two pump heads 670 mm long by 64 mm in diameter phosphate glass laser rods. When trains of Q-switched pulses are required, 70 mm diameter Pockels cells and dielectric polarizers are added to the oscillator cavity. The basic burst duration of 5 ms can be stretched to 10, 20, 40, 80,and 160 ms by sequencing the firing of flashlamps, with the longest pulse length attained by sequentially firing 1/4 heads. Trains of Q-switched pulses up to 10 kHz in repetition rate and 50 to 900 ns wide can be obtained by varying the cavity configuration and Pockels cell firing rate. Spatial distributions are flat-topped within about 10 percent. Overall efficiency for the oscillator with a CW waveform can exceed 4.8 percent.

  9. Continuous-wave and passively Q-switched laser performance of Nd:(LaxGd1-x)3Ga5O12 crystal at 1062 nm CW and PQS laser performance of Nd:LaGGG crystal at 1062 nm

    NASA Astrophysics Data System (ADS)

    Yang, H.; Fu, X.-W.; Jia, Z.-T.; He, J.-L.; Yang, X.-Q.; Zhang, B.-T.; Wang, R.-H.; Liu, X.-M.; Hou, J.; Lou, F.; Wang, Z.-W.; Yang, Y.

    2012-10-01

    The performance of diode-pumped continuous-wave (CW) and passively Q-switched (PQS) Nd:(LaxGd1-x)3Ga5O12 lasers at 1062 nm were demonstrated for the first time to our knowledge. The highest CW output power of 9.9 W was obtained, corresponding to an optical-to-optical efficiency of 42.9%. For the passive Q-switching operation, when the output coupler of Toc = 27% was adopted, the maximum output power of 3.97 W was obtained by a Cr4+:YAG saturable absorber with the initial transmission of T0 = 89.9%.While at T0 = 81.4% and Toc = 27%, the output power of 2.83 W, with pulse width of 7.4 ns and the repetition rate of 13.87 kHz, was obtained, corresponding to the maximum peak power of 27.6 kW and single pulse energy of 0.2 mJ, respectively.

  10. New insight in the treatment of refractory melasma: Laser Q-switched Nd: YAG non-ablative fractionated followed by intense pulsed light.

    PubMed

    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. PMID:26032175

  11. High-energy passively Q-switched laser operation of Yb:Ca3La2(BO3)4 disordered crystal.

    PubMed

    Wang, Lisha; Han, Wenjuan; Pan, Zhongben; Xu, Honghao; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-05-01

    Efficient high-energy passively Q-switched laser operation was demonstrated with Yb:Ca3La2(BO3)4 disordered crystal, producing an average output power of 3.0 W at 1018.7 nm, at a pulse repetition frequency of 5.0 kHz; the resulting pulse energy, duration, and peak power were 600 μJ, 5.3 ns, and 113.2 kW, respectively. PMID:27140354

  12. On the possibility of increasing the pulse energy of a passively Q-switched erbium glass minilaser

    SciTech Connect

    Izyneev, A A; Sadovskii, Pavel I; Sadovskii, S P

    2010-08-03

    A simple method to increase the output energy of a passively Q-switched erbium glass laser is proposed. Using the amplitude modulation of losses at the active element face, the fundamental mode was reliably suppressed and the laser operated in a selected higher-order mode. The output energy was experimentally increased by a factor of 2.1, and the range of allowable pump energy instability was extended threefold. (lasers)

  13. Optical parametric oscillator of quasi-phasematched LiNbO 3 pumped by a compact high repetition rate single-frequency passively Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Bäder, U.; Bartschke, J.; Klimov, I.; Borsutzky, A.; Wallenstein, R.

    1998-02-01

    We report on an efficient diode pumped compact source of pulsed tunable infrared radiation based on a high repetition rate single frequency passively Q-switched Nd:YAG laser and an optical parametric oscillator (OPO) of quasi-phase matched LiNbO 3. When pumped by 5.4 W of 810 nm cw diode laser radiation the Nd:YAG laser (which is passively Q-switched by a Cr 4+:GSGG saturable absorber) oscillates on a single-longitudinal mode and emits in a diffraction limited beam light pulses with duration of 2 ns, pulse energy of 100 μJ, repetition rate of 1.1 kHz and average power of 110 mW. This radiation excites an OPO of quasi-phase matched LiNbO 3. The OPO generates signal and idler radiation which is tunable in the range of 1.46-1.61 μm and 3.13-3.92 μm, respectively. Tuning is achieved by using 8 different poling periods ( Λ=28.5-29.9 μm) and by changing the crystal's temperature in the range of 80-160°C. The measured signal pulse energy is ES =22 μJ, the average signal output power PS =24 mW, the measured idler power PI =2.5 mW and the pump depletion 33%.

  14. Passively Q-switched Nd:YAG/Cr(4+):YAG bonded crystal microchip laser operating at 1112  nm and its application for second-harmonic generation.

    PubMed

    Fu, S G; Ouyang, X Y; Liu, X J

    2015-10-10

    A passively Q-switched Nd:YAG/Cr4+:YAG microchip laser operating at 1112 nm is demonstrated. Under a pump power of 5.5 W, a maximum average output power of 623 mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8 ns, the pulse energy and peak power were 39.3 μJ and 14 kW, respectively. Additionally, based on the 1112 nm laser, a 230 mW 556 nm green-yellow laser was achieved within an LBO crystal. PMID:26479822

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

    PubMed Central

    Tian, Brian Wei Cheng Anthony

    2015-01-01

    Objective: To demonstrate a combination laser therapy to treat Hori's nevus. Design: A prospective study. Setting: A Singapore-based clinic. Participants: Five female patients, aged 30-46 years, with bilateral malar Hori's nevus. Measurements: Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. Materials and Methods: The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm2, spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori's nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS) Nd:YAG at a fluence of 2.0 J/cm2, frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori's nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. Results: All five patients had above 80% improvement in their pigmentation and two (skin type III) achieved complete 100% clearance. Based on the patients’ subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. Conclusion: The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori's nevus. PMID:26865788

  16. Continuous wave and passively Q-switched Nd:Lu0.15Y0.85VO4 laser with 885 nm direct pumping

    NASA Astrophysics Data System (ADS)

    Li, Qi-nan; Zhao, Bin; Zhang, Tao; Li, Rei; Liu, Xiang-mei; Zheng, Ya-hui; Liu, Xiao-jun

    2015-05-01

    The 885 nm direct pumping directly into the 4F3/2 emitting level of Nd3+ is applied on an Nd:Lu0.15Y0.85VO4 crystal. The maximum output power of 2.8 W for continuous wave (CW) operation is obtained. For Q-switched operation, the maximum average output power is 1.2 W with pulse repetition of 23.69 kHz and pulse width of 35 ns at the pump power of 27.9 W. The high-quality fundamental transverse mode can be observed owing to the reduction of thermal effect for Nd:Lu0.15Y0.85VO4 crystal by 885 nm direct pumping.

  17. Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

    PubMed

    Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

    2009-07-01

    We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm. PMID:19571944

  18. 83 W yellow—green laser at 556 nm from frequency-doubling of a Q-switched Nd:YAG laser at 1112 nm in LBO

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  19. Induction of melasma by 1064-nm Q-switched neodymium:yttrium-aluminum-garnet laser therapy for acquired bilateral nevus of Ota-like macules (Hori nevus): A study on related factors in the Chinese population.

    PubMed

    Wang, Ben; Xie, Hong-Fu; Tan, Jun; Xie, Hong-Ju; Xu, Lin-Yong; Ding, Rong; Liu, Fang-Fen; Chen, Xiang; Jian, Dan; Li, Ji

    2016-06-01

    Laser treatment has emerged as a common treatment modality for acquired bilateral nevus of Ota-like macules (ABNOM). To identify the ratio of melasma induction and exacerbation before and after laser therapy for ABNOM and to observe the risk factors related to the induction and exacerbation of melasma by laser therapy, we analyzed related factors of 1268 adult Chinese patients who underwent 1064-nm Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (QNYL) treatment using case series and case-control studies. Overall, 24.0% of the ABNOM patients had mixed melasma. Among the ABNOM patients without melasma, after laser therapy the development of melasma was more frequently noted in patients older than 35 years (P < 0.0001), as well in patients whose ABNOM was less than 10 cm(2) (P = 0.027), ABNOM were light (similar to yellow-brown) in color (P = 0.021) and skin types were closer to type IV (P < 0.0001). New melasma lesions also appeared most frequently in the zygomatic region (P < 0.0001). Among the ABNOM patients with melasma, 89.5% experienced worsening of their melasma, irrespective of their related factors above. We concluded that the risk of inducing melasma is great after 1064-nm QNYL treatment in ABNOM patients, and particularly in the patients with both ABNOM and melasma. ABNOM patients should be treated as early as possible and before the age of 35 years. PMID:26777390

  20. Monolithic passively Q-switched Cr:Nd:GSGG microlaser

    NASA Astrophysics Data System (ADS)

    Schmitt, Randal L.

    2005-09-01

    Optical firing sets need miniature, robust, reliable pulsed laser sources for a variety of triggering functions. In many cases, these lasers must withstand high transient radiation environments. In this paper we describe a monolithic passively Q-switched microlaser constructed using Cr:Nd:GSGG as the gain material and Cr4+:YAG as the saturable absorber, both of which are radiation hard crystals. This laser consists of a 1-mm-long piece of undoped YAG, a 7-mm-long piece of Cr:Nd:GSGG, and a 1.5-mm-long piece of Cr4+:YAG diffusion bonded together. The ends of the assembly are polished flat and parallel and dielectric mirrors are coated directly on the ends to form a compact, rugged, monolithic laser. When end pumped with a diode laser emitting at ~807.6 nm, this passively Q-switched laser produces ~1.5-ns-wide pulses. While the unpumped flat-flat cavity is geometrically unstable, thermal lensing and gain guiding produce a stable cavity with a TEM00 gaussian output beam over a wide range of operating parameters. The output energy of the laser is scalable and dependent on the cross sectional area of the pump beam. This laser has produced Q-switched output energies from several μJ per pulse to several 100 μJ per pulse with excellent beam quality. Its short pulse length and good beam quality result in high peak power density required for many applications such as optically triggering sprytrons. In this paper we discuss the design, construction, and characterization of this monolithic laser as well as energy scaling of the laser up to several 100 μJ per pulse.

  1. Diode-pumped Q-switched Nd{sup 3+} : YAG laser operating in a wide temperature range without thermal stabilisation of pump diodes

    SciTech Connect

    Vainshenker, A E; Vilenskiy, A V; Kazakov, A A; Lysoy, B G; Mikhailov, L K; Pashkov, V A

    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)

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

    SciTech Connect

    Malov, Aleksei N; Orishich, Anatolii M; Shulyat'ev, Viktor B

    2011-11-30

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

  3. Visualization and simulation of a linear explosive-induced pyroshock wave using Q-switched laser and phased array transducers in a space launcher composite structure

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Jang, Jae-Kyeong; Choi, Mijin; Kong, Cheol-Won

    2015-04-01

    During space flights, pyrotechnic devices are used for various purposes such as separation of boosters, satellites, fairings, and stages. In particular, the prediction of high shock structural response induced by linear explosives is important for safe operation of pyrotechnic devices. In general, repetitive explosive testing using distributed accelerometers is widely used, but multiple test structures are usually necessary because they are easily damaged and not reusable. This paper pertains to a nondestructive technology to replace the damage-causing, time-consuming, expensive, dangerous, and low-repeatability explosive test with a laser-induced shock test. The method proposed in this paper predicts nondestructively the linear explosive-induced pyroshock wave, visualizes its propagation, and allows the simulation of some detonation conditions. A ballistic test based on a linear explosive and noncontact laser Doppler vibrometer (LDV) as well as a nondestructive pyroshock test using laser-induced shock and PZT array sensors is performed in a 12.68-mm thick composite sandwich panel. The optimal laser-induced shock experimental conditions to predict real pyroshock response spectra (SRSs) are investigated by controlling the optical characteristics of the laser beam and adjusting the frequency bands in signal acquisition. The similarity of the SRS of the conditioned laser-induced shock to that of the real explosive pyroshock is evaluated with the mean acceleration difference. Next, the experimentally-determined optimal conditions are applied to arbitrary points in the laser-induced shock scanning area. Finally, it is shown that the proposed method will allow nondestructive and quantitative pyroshock testing, pyroshock wave propagation visualization showing the direction and magnitude of principal wave propagation, and detonation speed simulation depending on explosive type and detonation initiation point and direction.

  4. 160mJ and 9ns electro-optics Q-switched conductively cooled 1047nm Nd:YLF laser

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Ma, Jian; Lu, Tingting; Ma, Xiuhua; Zhu, Xiaolei

    2015-02-01

    A compact diode side-pumped conductively cooled 1047 nm Nd:YLF slab laser with high energy and short pulse width is developed. Through ray tracing method, we design a home-made pump module to homogenize the pump intensity. Based on the Possion equation, a thermal conduct model of side-pump laser is established. The temperature distribution in laser crystal is obtained, and the thermal lens is caculated. With the absorbed pump energy of 818 mJ, the maximum output energy of 228 mJ is achieved in free-running mode. At a repetition rate of 50 Hz, 160 mJ, 9 ns 1047 nm infrared light is obtained under the maximum absorbed pump energy, and the slope efficiency is 27.8%.

  5. 2-μm high-power multiple-frequency single-mode Q-switched Ho:YLF laser for DIAL application

    NASA Astrophysics Data System (ADS)

    Gibert, Fabien; Edouart, Dimitri; Cénac, Claire; Le Mounier, Florian

    2014-09-01

    We report on the development and the demonstration of a two-wavelength single-frequency laser oscillator based on Ho:YLF crystal. This laser is especially suitable for application as a transmitter in differential absorption lidar (DIAL)/integrated path differential absorption (IPDA) measurements of atmospheric carbon dioxide (CO2) using the R30 CO2 absorption line at 2,050.967 nm. The oscillator consists in a fiber-coupled and free-space solid-state hybrid system and can be used in high-energy middle-rate or moderate-energy high-rate configurations. The latter produced On and Off sequentially single-frequency laser pulses with 13 mJ of energy at a repetition rate of 2 kHz and pulse duration of 42 ns. The pulse energy and frequency stabilities are specially documented in free-running, single-frequency and two-frequency seeding single-mode operations. Standard deviation is 7.7 % for pulse energy and 2 MHz for frequency stability for the two-wavelength seeding operation. Allan variance plot shows that frequency fluctuations are reduced below 70 kHz for 10 s of averaging which is suitable for accurate CO2 DIAL or IPDA measurements.

  6. Electro-optic Q-switch driver design specifics

    NASA Astrophysics Data System (ADS)

    Melnikov, Konstantin

    2010-07-01

    Different schematic designs of Q-Switch Drivers for Pockels Cell based optical arrangement are considered. Schematic solutions of Q-Switch driver design are analyzed. Marx Bank based Generator and High Voltage Switch Schematics are compared. Parameters of constructed Q-Switch Drivers are presented.

  7. Electro-optic Q-switch driver design specifics

    NASA Astrophysics Data System (ADS)

    Melnikov, Konstantin

    2011-03-01

    Different schematic designs of Q-Switch Drivers for Pockels Cell based optical arrangement are considered. Schematic solutions of Q-Switch driver design are analyzed. Marx Bank based Generator and High Voltage Switch Schematics are compared. Parameters of constructed Q-Switch Drivers are presented.

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

    SciTech Connect

    Lin, J.; Yan, K.; Zhou, Y.; Xu, L. X. Gu, C.; Zhan, Q. W.

    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. Multiple acousto-optic q-switch

    DOEpatents

    Deason, Vance A.

    1993-01-01

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  10. Multiple acousto-optic q-switch

    DOEpatents

    Deason, Vance A.

    1993-12-07

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  11. Exploration of water jet generated by Q-switched laser induced water breakdown with different depths beneath a flat free surface.

    PubMed

    Chen, Ross C C; Yu, Y T; Su, K W; Chen, J F; Chen, Y F

    2013-01-14

    The dynamics of a water jet on a flat free surface are investigated using a nanosecond pulsed laser for creating an oscillating bubble with different depths beneath the free surface. A thin jet is shown to deform a crater surface resulted from surface depression and cause a circular ring-shaped crater on the connection surface between the crater of surface depression and the thin jet. The collapse of this circular ring-shaped crater is proposed to the crown-like formation around a thick jet. The evolution of the bubble depth suggests a classification of four distinctive ranges of the bubble depths: non-crown formation when the parameter of bubble depth over the maximum bubble radius γ ≤ 0.5, unstable crown formation when 0.5 ≤ γ ≤ 0.6, crown-like structure with a complete crown wall when 0.6 ≤ γ ≤ 1.1, and non-crown formation when 1.1 ≤ γ. Furthermore, the orientation of the crown wall gradually turns counterclockwise to vertical direction with increasing γ from 0.5 to 1.1, implying a high correlation between the orientation of the crown wall and the depth of the bubble. This correlation is explained and discussed by the directional change of the jet eruption from the collapse of circular ring-shaped crater. PMID:23388938

  12. Gold nanoparticles as a saturable absorber for visible 635 nm Q-switched pulse generation.

    PubMed

    Wu, Duanduan; Peng, Jian; Cai, Zhiping; Weng, Jian; Luo, Zhengqian; Chen, Nan; Xu, Huiying

    2015-09-01

    Gold nanoparticle (GNP) possesses saturable absorption bands in the visible region induced by surface plasmon resonance (SPR). We firstly applied the GNP as a visible saturable absorber (SA) for the red Q-switched pulse generation. The GNPs were embedded in polyvinyl alcohol (PVA) for film-forming and inserted into a praseodymium (Pr(3+))-doped fiber laser cavity to achieve 635 nm passive Q-switching. The visible 635 nm Q-switched fiber laser has a wide range of pulse-repetition-rate from 285.7 to 546.4 kHz, and a narrow pulse width of 235 ns as well as the maximum output power of 11.1 mW. The results indicate that the GNPs-based SA is available for pulsed operation in the visible spectral range. PMID:26368498

  13. Treatment of melasma with mixed parameters of 1,064-nm Q-switched Nd:YAG laser toning and an enhanced effect of ultrasonic application of vitamin C: a split-face study.

    PubMed

    Lee, Mei-Ching; Chang, Chun-Shin; Huang, Yau-Li; Chang, Shyue-Luen; Chang, Chih-Hsiang; Lin, Ying-Fang; Hu, Sindy

    2015-01-01

    Melasma is an acquired pigment disorder showing symmetrical hyperpigmentation of the face characterized by light to dark brown patches with indistinct borders on both cheeks. Melasma is prevalent in middle-aged women with harmless hormone imbalances. It is also known as the mask of pregnancy and is prevalent in most child-bearing women. It fluctuates month by month, and yet, there is no promising treatment. The Q-switched neodymium-doped yttrium aluminum garnet (QS-Nd:YAG) laser (1,064-nm wavelength) was introduced in Asia years ago for both skin toning and treatment of facial pigment. This low-fluence, 1,064-nm QS-Nd: YAG laser also reportedly improved melasma. Adjunctive treatments such as vitamin C iontophoresis or chemical peels were recommended in other reports. The technique using the 1,064-nm QS-Nd:YAG laser for toning and the enhancement of adjunctive treatments need further investigation and long-term follow-up before recommendations for the ideal protocol for melasma treatment can be made. The aim of this study is to evaluate the improvement of melasma using different parameters with the 1,064-nm QS-Nd:YAG laser with ultrasonic application of topical vitamin C. Eight patients, ranging in age from 32 to 45 years (mean 37 years), with long-term melasma were studied. Most of the melasma cases were dermal or mixed-type melasma. The patients had no cosmetic treatment (laser, intense pulsed light, or chemical peel) 1 year prior to the study. The entire face of each patient was treated with the 1,064-nm QS-Nd:YAG laser for four sessions at 1-month intervals. The laser treatment was divided into three parts with different parameters. First, each patient underwent whole face exposure for one pass with an 8-mm spot size at a power of 2.0 J/cm(2). Next, the spot size was shifted to 6 mm at a power of 3.5 J/cm(2) for one full-face pass, and then ended with a 4-mm spot size at 3.2 J/cm(2) for one full-face pass, with multiple passes for the main lesions. The end point

  14. Single-mode deep-UV light source at 191.7  nm by seventh-harmonic generation of a high-power, Q-switched, injection-locked 1342  nm Nd:YVO₄ laser.

    PubMed

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

    2016-03-10

    A single-mode deep-UV laser at 191.7 nm is demonstrated by seventh-harmonic generation of a single-mode 1342 nm Nd:YVO₄ laser. The fundamental laser is an injection-locked, Q-switched ring laser at 10 kHz pulse repetition frequency. By cascaded second-harmonic and sum-frequency generation, an average power of 230 mW at 191.7 nm is achieved. At 185 mW, the setup features a Gaussian beam with a beam quality factor of M²<1.5. A pulse duration of 9 ns with pulse energy fluctuations of σ<3% is obtained. The long-term spectral width is approximately 240 MHz full width at half-maximum, measured with a homemade scanning confocal Fabry-Perot interferometer. This work opens possibilities in fiber Bragg grating production, allowing the inscription of long gratings. PMID:26974775

  15. Multi-Billion Shot, High-Fluence Exposure of Cr(4+): YAG Passive Q-Switch

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Dallas, Joseph L.; Afzal, Robert S.

    1997-01-01

    NASA's Goddard Space Flight Center is developing the Geoscience Laser Altimeter System (GLAS) employing a diode pumped, Q-Switched, ND:YAG laser operating at 40 Hz repetition rate. To meet the five-year mission lifetime goal, a single transmitter would accumulate over 6.3 billion shots. Cr(4+):YAG is a promising candidate material for passively Q-switching the laser. Historically, the performance of saturable absorbers has degraded over long-duration usage. To measure the multi-billion shot performance of Cr(4+):YAG, a passively Q-switched GLAS-like oscillator was tested at an accelerated repetition rate of 500 Hz. The intracavity fluence was calculated to be approximately 2.5 J/cm(exp 2). The laser was monitored autonomously for 165 days. There was no evidence of change in the material optical properties during the 7.2 billion shot test.. All observed changes in laser operation could be attributed to pump laser diode aging. This is the first demonstration of multi-billion shot exposure testing of Cr(4+):YAG in this pulse energy regime

  16. Continuous-Wave and Actively Q-Switched Diode-Pumped Er:LuAG Ring Laser at 1650 nm

    NASA Astrophysics Data System (ADS)

    Tong-Yu, Dai; Xu-Guang, Xu; Lin, Ju; Jing, Wu; Zhen-Guo, Zhang; Bao-Quan, Yao; Ye, Zhang

    2016-06-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 61308009 and 61405047, the China Postdoctoral Science Foundation Funded Project under Grant No 2013M540288, the Fundamental Research Funds for the Central Universities under Grant Nos HIT.NSRIF.2014044 and HIT.NSRIF.2015042, the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310, and the Heilongjiang Postdoctoral Science Foundation Funded Project under Grant No LBH-Z14085.

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

    SciTech Connect

    Xu, X. T.; Zhai, J. P.; Wang, J. S.; Chen, Y. P.; Yu, Y. Q.; Zhang, M.; Li, I. L.; Ruan, S. C.; Tang, Z. K.

    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.

  18. Q-switching in the electron backward-wave oscillator

    SciTech Connect

    Denisov, G. G.; Kuzikov, S. V.; Savilov, A. V.

    2011-10-15

    The use of Q-switching (periodical modulation of the feedback factor) is proposed for the electron backward-wave oscillator (BWO). This can be a way to realize regimes of a stable generation of periodical short high-power rf pulses with relatively high averaged efficiency. As compared to the conventional regime of the stable generation of a BWO with no feedback, in the Q-switched BWO the averaged electronic efficiency can be increased by an order of magnitude, whereas the peak power of output rf pulses is 40-50 times higher.

  19. Solid state saturable absorbers for Q-switching at 1 and 1.3μm: investigation and modeling

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Arátor, Pavel; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav; Kokta, Milan R.

    2008-02-01

    Yttrium and Lutecium garnets (YAG and LuAG) doped by Chromium or Vanadium ions (Cr 4+ or V 3+) were investigated as saturable absorbers potentially useful for passive Q-switching at wavelengths 1 μm and/or 1.3 μm. For comparison also color center saturable absorber LiF:F - II and Cobalt doped spinel (Co:MALO) were studied. Firstly, low power absorption spectra were recorded for all samples. Next, absorbers transmission in dependence on incident energy/power density was measured using the z-scan method. Crystals Cr:YAG, Cr:LuAG, V:YAG, and LiF:F - II were tested at wavelength 1064 nm. Therefore Alexandrite laser pumped Q-switched Nd:YAG laser was used as a radiation source (pulse length 6.9 ns, energy up to 1.5 mJ). Crystals V:YAG, V:LuAG, and Co:MALO were tested at wavelength 1338 nm. So diode pumped Nd:YAG/V:YAG microchip laser was used as a radiation source (pulse length 6.2 ns, energy up to 0.1 mJ). Using measured data fitting, and by their comparison with numerical model of a "thick" saturable absorber transmission for Q-switched Gaussian laser beam, following parameters were estimated: saturable absorber initial transmission T 0, saturation energy density w s, ground state absorption cross-section σ GSA, saturated absorber transmission T s, excited state absorption cross-section σ ESA, ratio γ = σ GSA/σ ESA, and absorbing ions density. For V:YAG crystal, a polarization dependence of T s was also investigated. With the help of rate equation numerical solution, an impact of saturable absorber parameters on generated Q-switched pulse properties was studied in plane wave approximation. Selected saturable absorbers were also investigated as a Q-switch and results were compared with the model.

  20. Treatment of facial skin using combinations of CO2, Q-switched alexandrite, and/or flashlamp-pumped dye and/or erbium lasers in the same treatment session

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Richard E.; Manuskiatti, Woraphong; Goldman, Mitchel P.

    1998-07-01

    Skin aging caused from chronological and photodamage processes results in many alterations in skin appearance. In many circumstances, patients who pursue CO2 laser resurfacing for facial rejuvenation are also concerned with other photoaging alternations that are beyond the efficacy of the CO2 laser. We demonstrated an approach to aged facial skin by using combined treatments of appropriate lasers.