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q switched laser

Erica Roitero, Federico Lasserre, Marc Anglada, Frank Mücklich, Emilio Jiménez-Piqué
OBJECTIVE: The aim of this work is to generate micrometric linear patterns with different topography on dental grade zirconia by means of UV laser interference and to assess the quality of the produced surface, both in term of the geometry produced and of the surface damage induced in the material. METHODS: The third harmonic of a Q-switched Nd:YAG laser (355nm, pulse duration of 10ns and repetition rate of 1Hz) was employed to pattern the surface of 3Y-TZP with micrometric-spaced lines...
October 10, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Ádám Krolopp, Attila Csákányi, Dóra Haluszka, Dániel Csáti, Lajos Vass, Attila Kolonics, Norbert Wikonkál, Róbert Szipőcs
A novel, Yb-fiber laser based, handheld 2PEF/SHG microscope imaging system is introduced. It is suitable for in vivo imaging of murine skin at an average power level as low as 5 mW at 200 kHz sampling rate. Amplified and compressed laser pulses having a spectral bandwidth of 8 to 12 nm at around 1030 nm excite the biological samples at a ~1.89 MHz repetition rate, which explains how the high quality two-photon excitation fluorescence (2PEF) and second harmonic generation (SHG) images are obtained at the average power level of a laser pointer...
September 1, 2016: Biomedical Optics Express
Yanmin Duan, Haiyong Zhu, Yaoju Zhang, Ge Zhang, Jian Zhang, Dingyuan Tang, A A Kaminskii
An intra-cavity RbTiOPO4 (RTP) cascade Raman laser was demonstrated for efficient multi-order Stokes emission. An acousto-optic Q-switched Nd:YAlO3 laser at 1.08 μm was used as the pump source and a 20-mm-long x-cut RTP crystal was used as the Raman medium to meet the X(Z,Z)X Raman configuration. Multi-order Stokes with multiple Raman shifts (~271, ~559 and ~687 cm(-1)) were achieved in the output. Under an incident pump power of 9.5 W, a total average output power of 580 mW with a pulse repetition frequency of 10 kHz was obtained...
September 26, 2016: Scientific Reports
Jinhwa Gene, Nam Hun Park, Hwanseong Jeong, Sun Young Choi, Fabian Rotermund, Dong-Il Yeom, Byoung Yoon Kim
We demonstrate an optically tunable graphene saturable absorber to manipulate the laser operation in pulsed fiber laser system. Owing to the strongly enhanced evanescent field interaction with monolayer graphene, we could realize an efficient control of modulation depth in the graphene saturable absorber by optical means through cross absorption modulation method. By integrating the tunable graphene saturable absorber into the fiber laser system, we could switch the laser operation from Q-switching through Q-switched mode-locking to continuous wave mode-locking by adjusting only the optical power of the control beam...
September 19, 2016: Optics Express
Qin Cui, Jinglong Lan, Zhi Lin, Bin Xu, Huiying Xu, Zhiping Cai, Xiaodong Xu, Jian Zhang, Jun Xu
We report on high-performance infrared lasers at 0.94 μm based on quasi-three-level transition of F<sub>3/2</sub>4→I<sub>9/2</sub>4 in Nd:LuYAG mixed crystal, for the first time to our knowledge. The maximum output power was achieved to 5.64 W with slope efficiency of approximately 52.5% at 946 nm. The simultaneous dual-wavelength laser at 939 and 946 nm is also obtained with maximum output power of 3.61 W and slope efficiency of 34.8% by introducing a glass etalon into the cavity...
September 10, 2016: Applied Optics
Huanian Zhang, Bowen Li, Jie Liu
The performance of a laser-diode-pumped passively Q-switched Nd:LGGG laser at 1423.2 nm with gold nanobipyramids (Au-NBPs) as a saturable absorber was demonstrated. An average output power of 125 mW was obtained at a pump power of 12.2 W, corresponding to an optical-to-optical conversion efficiency of 1.36% and a slope efficiency of 1.78%. A minimum pulse width of 514 ns at a pulse repetition rate of 98.6 kHz was obtained at a pump power of 12.2 W. To the best of our knowledge, this is the first report focusing on the application of Au-NBPs as a saturable absorber for pulse laser operation in the eye-safe region...
September 10, 2016: Applied Optics
Lachlan Harris, Myles Clark, Peter Veitch, David Ottaway
We report a compact cavity-dumped Q-switched Er:YAG laser that produces pulses with 4.5 ns full width at half-maximum duration and 10 mJ energy. To the best of our knowledge, the resulting 2 MW peak power is the highest reported to date from a 1645 nm Er:YAG laser.
September 15, 2016: Optics Letters
Qiangbing Guo, Yunhua Yao, Zhi-Chao Luo, Zhipeng Qin, Guoqiang Xie, Meng Liu, Jia Kang, Shian Zhang, Gang Bi, Xiaofeng Liu, Jianrong Qiu
Field effect relies on the nonlinear current-voltage relation in semiconductors; analogously, materials that respond nonlinearly to optical field can be utilized for optical modulation. For instance, nonlinear optical materials bearing saturable absorption (SA) features an on-off switching behavior at the critical pumping power, thus enabling ultrafast laser pulse generation with high peak power. SA have been observed in diverse materials preferably in their nanoscale form, including both gaped semiconductor nanostructures and gapless materials like graphene; while the presence of optical bandgap and small carrier density have limited the active spectral range and intensity...
September 13, 2016: ACS Nano
Van Phuc Nguyen, Suhyun Park, Junghwan Oh, Hyun Wook Kang
Photoacoustic imaging (PAI) is a hybrid imaging modality with high resolution and sensitivity that can be beneficial for cancer staging. Due to insufficient endogenous photoacoustic (PA) contrast, the development of exogenous agents is critical in targeting cancerous tumors. The current study demonstrates the feasibility of marine-oriented material, astaxanthin, as a biocompatible PA contrast agent. Both silicon tubing phantoms and ex vivo bladder tissues are tested at various concentrations (up to 5 mg/ml) of astaxanthin to quantitatively explore variations in PA responses...
September 12, 2016: Journal of Biophotonics
La-Ga Tong, Yan Wu, Bin Wang, Xue Gang Xu, Han-Deng Tu, Hong Duo Chen, Yuan Hong Li
BACKGROUND: Melasma is the most common and distressing pigmentary disorder presenting to dermatology clinics.Various treatment protocols for melasma have been suggested in the previous literature, and applied in various clinical settings. However, no satisfactory therapy has been widely accepted. OBJECTIVE: To evaluate the efficiency and safety of a combination treatment with fractional Q-switched ruby laser (QSRL) and intense pulsed light (IPL) for melasma of Chinese population...
September 3, 2016: Journal of Cosmetic and Laser Therapy: Official Publication of the European Society for Laser Dermatology
Jae-Jun Choi, Soo-Jin Choi, Jack J Yoh
Categorized certified reference materials simulating metal, rock, soils, or dusts are used to demonstrate the standoff detection capability of laser-induced breakdown spectroscopy (LIBS) at severely low pressure conditions. A Q-switched Nd:YAG laser operating at 1064 nm with 17.2-50 mJ energy per pulse was used to obtain sample signals from a distance of 5.5 m; the detection sensitivity at pressures down to 0.01 torr was also analyzed. The signal intensity response to pressure changes is explained by the ionization energy and electronegativity of elements, and from the estimated full width half-maximum (FWHM) and electron density, the decrease in both background noise and line broadening makes it suitable for low pressure detection using the current standoff LIBS configuration...
September 2016: Applied Spectroscopy
Jiangming Xu, Jun Ye, Hu Xiao, Jinyong Leng, Jian Wu, Hanwei Zhang, Pu Zhou
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...
August 22, 2016: Optics Express
Shigeo Nagano, Motohiro Kumagai, Ying Li, Tetsuya Ido, Shoken Ishii, Kohei Mizutani, Makoto Aoki, Ryohei Otsuka, Yuko Hanado
We disseminated an ultra-broadband optical frequency reference based on a femtosecond (fs)-laser optical comb through a kilometer-scale fiber link. Its spectrum ranged from 1160 nm to 2180 nm without additional fs-laser combs at the end of the link. By employing a fiber-induced phase noise cancellation technique, the linewidth and fractional frequency instability attained for all disseminated comb modes were of order 1 Hz and 10<sup>-18</sup> in a 5000 s averaging time. The ultra-broad optical frequency reference, for which absolute frequency is traceable to Japan Standard Time, was applied in the frequency stabilization of an injection-seeded Q-switched 2051 nm pulse laser for a coherent light detection and ranging LIDAR system...
August 22, 2016: Optics Express
Jie Xu, Jun Dong
By using combinations of appropriate laser crystals, we simulated a Yb:YAG/Cr<sup>4+</sup>:YAG composite crystal with a Cr,Yb:YAG interface layer. The effect of the Cr,Yb:YAG interface layer on the laser performance of the Yb:YAG/Cr<sup>4+</sup>:YAG composite crystal has been investigated for the first time to our best knowledge. The formation of the Cr,Yb:YAG interface layer in the Yb:YAG/Cr<sup>4+</sup>:YAG composite crystal has a negative impact on average output power, optical efficiency, as well as single pulse energy and peak power...
August 10, 2016: Applied Optics
Hiroki Tanaka, Ryosuke Kariyama, Kodai Iijima, Fumihiko Kannari
We demonstrate intracavity second-harmonic generation at 320 nm of a diode-pumped praseodymium-doped YLF laser Q-switched by a Cr<sup>4+</sup>: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.
August 10, 2016: Applied Optics
Tian-Hua Xu, Yuan-Hong Li, John Z S Chen, Xing-Hua Gao, Hong-Duo Chen
The objective of this study was to evaluate the efficacy and safety of using a 694-nm fractional Q-switched ruby laser to treat infraorbital dark circles. Thirty women with infraorbital dark circles (predominant color: dark/brown) participated in this open-labeled study. The participants received eight sessions of 694-nm fractional Q-switched ruby laser treatment using a fluence of 3.0-3.5 J/cm(2), at an interval of 7 days. The melanin deposition in the lesional skin was observed in vivo using reflectance confocal microscopy (RCM)...
August 13, 2016: Lasers in Medical Science
W K Chang, H P Chung, Y Y Lin, Y H Chen
We report on the design and experimental demonstration of an electro-optically tunable, pulsed intracavity optical parametric oscillator (IOPO) based on a unique fan-out double-prism domain periodically poled lithium niobate (DPD PPLN) in a diode-pumped Nd:YVO<sub>4</sub> laser. The PPLN device combines the functionalities of fan-out and ramped duty-cycle domain structured nonlinear crystals, working simultaneously as a continuous grating-period quasi-phase-matched optical parametric downconverter and an electro-optic beam deflector/Q switch in the laser system...
August 15, 2016: Optics Letters
Chao Luan, Kejian Yang, Jia Zhao, Shengzhi Zhao, Lei Song, Tao Li, Hongwei Chu, Junpeng Qiao, Chao Wang, Zhen Li, Shouzhen Jiang, Baoyuan Man, Lihe Zheng
We prepared WS<sub>2</sub> 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 WS<sub>2</sub> 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 WS<sub>2</sub> could be a kind of promising SA for solid-state 2 μm lasers...
August 15, 2016: Optics Letters
Tian Qiao, Weicheng Chen, Wei Lin, Zhongmin Yang
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...
August 8, 2016: Optics Express
Taichi Goto, Ryohei Morimoto, John W Pritchard, Mani Mina, Hiroyuki Takagi, Yuichi Nakamura, Pang Boey Lim, Takunori Taira, M Inoue
High-power giant pulses can be used applied in various applications with Q-switched micro-lasers. This method can shorten the pulse duration; however, active control is currently impossible in micro-lasers. To achieve precise pulse control while maintaining compactness and simplicity, we exploit the magneto-optical effect in magnetic garnet films with micromagnetic domains that can be actively controlled by a pulsed magnetic field. Our Q-switching technique enhances the output power by a factor of 4 × 10<sup>3</sup>...
August 8, 2016: Optics Express
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