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q switched laser

Yujin Chen, Yanfu Lin, Jianhua Huang, Xinghong Gong, Zundu Luo, Yidong Huang
A composite crystal consisting of a 1.5-mm-thick Er:Yb:YAl3(BO3)4 crystal between two 1.2-mm-thick sapphire crystals was fabricated by the thermal diffusion bonding technique. Compared with a lone Er:Yb:YAl3(BO3)4 crystal measured under the identical experimental conditions, higher laser performances were demonstrated in the sapphire/Er:Yb:YAl3(BO3)4/sapphire composite crystal due to the reduction of the thermal effects. End-pumped by a 976 nm laser diode in a hemispherical cavity, a 1.55 μm continuous-wave laser with a maximum output power of 1...
January 8, 2018: Optics Express
Haiyong Zhu, Junhong Guo, Yanmin Duan, Jing Zhang, Yongchang Zhang, Changwen Xu, Hongyan Wang, Dianyuan Fan
An intra-cavity optical parametric oscillator (OPO) emitting at 1.7 μm derived by Nd:YVO4 self-Raman laser is demonstrated in this Letter, with a KTiOAsO4 (KTA) crystal used as nonlinear optical crystal. A laser diode end-pumped acousto-optic Q-switched Nd:YVO4 self-Raman laser at 1176 nm was employed as the pump source. At an incident pump power of 12.1 W and a pulse repetition frequency of 60 kHz, average output power up to 1.2 W signal light at 1742 nm was obtained, with diode-to-signal conversion efficiency of 10%...
January 15, 2018: Optics Letters
Kohei Mizutani, Shoken Ishii, Makoto Aoki, Hironori Iwai, Ryohei Otsuka, Hirotake Fukuoka, Takayoshi Isikawa, Atsushi Sato
A 2 μm Ho-doped ytrrium lithium fluoride (Ho:YLF) laser end-pumped by a 1.94 μm Tm:fiber laser was developed. A laser system of a ring resonator oscillator and amplifier was operated at repetition rates of 200-5000 Hz at room temperature. The Q-switched outputs were 7.4 W at 5000 Hz and 4.25 W at 200 Hz. Injection seeding was applied to the ring resonator, and single-mode laser emission was obtained. The Tm:fiber-laser-pumped Ho:YLF laser was first used for Doppler wind lidar measurements, and wind profiles were obtained up to ranges of about 15 km in a range resolution of 96 m and an integration time of 1 s...
January 15, 2018: Optics Letters
Brian Cole, Lew Goldberg, A D Hays
We describe a compact, highly efficient, diode-pumped, mechanically Q-switched Tm:YAP laser operating near 2 μm. The Q-switch, based on a torsion spring resonant mirror scanner, had negligible optical loss and required very low electrical drive power. At a 10 kHz pulse repetition frequency, the laser generated an average output power of 10.5 W at 1.94 μm, Q-switched pulse energy of 1.05 mJ, a pulse length of 31 ns, and a peak power of 34 kW. The Q-switched laser exhibited maximum optical and electrical efficiencies of 51% and 26%, respectively...
January 15, 2018: Optics Letters
Leonard Pomeranz, John McCarthy, Randy Day, Kevin Zawilski, Peter Schunemann
We report on first demonstrations of CdSiP2-based optical parametric oscillators that are pumped by eye-safe Q-switched nanosecond laser sources operating at 1.57 μm. One device reached 40% optical conversion efficiency generating 10 mJ of energy near degeneracy in the 3 μm region. Angle tuning of a similar device through the middle infrared was demonstrated with the signal and idler waves being tuned from 2.28 μm to 5.05 μm.
January 1, 2018: Optics Letters
Jung Woo Han, Juhye Choi, Young Shin Kim, Jina Kim, Ralf Brinkmann, Jungmook Lyu, Tae Kwann Park
PURPOSE: This study investigated microglia and inflammatory cell responses after selective retina therapy (SRT) with microsecond-pulsed laser in comparison to continuous-wave laser photocoagulation (cwPC). METHODS: Healthy C57BL/6 J mice were treated with either a train of short pulses (SRT; 527-nm, Q-switched, 1.7-μs pulse) or a conventional thermal continuous-wave (532-nm, 100-ms pulse duration) laser. The mice were sacrificed and their eyes were enucleated 1, 3, 7, and 14 days after both laser treatments...
January 10, 2018: Graefe's Archive for Clinical and Experimental Ophthalmology
K H Mahmoud, Khaled A Elsayed, T S Kayed
Casting solution method has been used to prepare Polyvinyl alcohol (PVA) film. The prepared film has been irradiated with a laser beam of 6ns Q-switched Nd:YAG laser (Lotus II) operating at 10Hz and fourth harmonic wavelength, 266nm, at different irradiation times. Optical absorbance of the irradiated sample was studied in the wavelength region between 200 and 800nm. The absorption peak shift of 272nm towards the longer wavelengths region and the increase of absorption as the irradiation time increases, are related to the increase in crosslinking network...
December 21, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Qinduan Zhang, Jun Chang, Qiang Wang, Zongliang Wang, Fupeng Wang, Zengguang Qin
We proposed a new method for gas detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser by merging a transmission PAS cell (resonant frequency f₀ = 5.3 kHz) inside the fiber laser cavity. The Q-switching was achieved by an acousto-optic modulator, achieving a peak pulse power of ~679 mW in the case of the acousto-optic modulation signal with an optimized duty ratio of 10%. We used a custom-made fiber Bragg grating with a central wavelength of 1530.37 nm (the absorption peak of C₂H₂) to select the laser wavelength...
December 25, 2017: Sensors
Wenyou Yu, Jiafang Zhu, Wenxin Yu, Dongze Lyu, Xiaoxi Lin, Zhen Zhang
BACKGROUND: Q-switched alexandrite lasers (QSAL) have been used for the treatment of acquired bilateral nevus of Ota-like macules (ABNOM). Currently, picosecond alexandrite laser (PSAL) pulses have become available for pigmentary disorders. However, no studies have compared PSAL and QSAL in the treatment of ABNOM. OBJECTIVE: To compare the efficacy and safety of a PSAL and a QSAL in the treatment of ABNOM. METHODS: Each patient (n = 30) received three treatments at six-month intervals...
December 26, 2017: Journal of the American Academy of Dermatology
Ding Wu, Liying Sun, Ping Liu, Ran Hai, Hongbin Ding
In this work, emission signals of laser-induced breakdown (LIBS) plasma of a flowing liquid jet in the absence and presence of an air-supported glow discharge have been investigated. In combination with a needle-to-needle glow discharge, a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 5 ns) with power density ∼1010 W/cm2 was used to generate a plasma from a liquid jet. Emission lines of Mg, Ca, Al, Li, Na, and K all showed significant enhancements in the presence of the glow discharge...
January 1, 2017: Applied Spectroscopy
Yang Liu, Kai Zhong, Jialin Mei, Chu Liu, Jie Shi, Xin Ding, Degang Xu, Wei Shi, Jianquan Yao
A compact and stable terahertz (THz) source is demonstrated based on difference frequency generation (DFG) pumped by an efficient dual-wavelength acousto-optic (AO) Q-switched solid-state Nd:YLF laser with composite gain media (a-cut and c-cut) in the coaxial pumping configuration. Optimal power ratio and pulse synchronization of the orthogonal polarized 1047/1053 nm dual-wavelength laser could be realized by varying the pump focusing depth and/or pump wavelength. The total power of 2.92 W was obtained at 5 kHz pumped by 10-W laser-diode power at 803 nm...
December 11, 2017: Optics Express
Baroni Adone, De Filippis Anna, Oliviero Giovanni, Fusco Alessandra, Perfetto Brunella, Buommino Elisabetta, Donnarumma Giovanna
Candida albicans is an opportunistic pathogen commensal in the oral cavity, vagina, and healthy skin. Common therapeutic options for fungal infections are topical or systemic antifungal drugs. Recently, in cutaneous pathologies, lasers and light-based treatments have emerged showing few contraindications and minimal side effects. The Q-switched (Nd-YAG) laser at a wavelength of 1064 nm has been shown to be useful in dermatology, dentistry, and some other medical specialties. It is used to treat onychomycoses, warts, and wounds and in some other treatments...
December 14, 2017: Lasers in Medical Science
Chun Yu Cho, Yung Fu Chen, Ge Zhang, Wei Dong Chen, Hsing Chih Liang
A continuous-wave (cw) self-mode-locked Tm:YAG laser at 2015 nm is successfully demonstrated by suppressing the self-pulsing behavior. By using rate equations to simulate the laser temporal dynamic, the theoretical analysis indicates that the reabsorption-induced self-pulsing for the Tm:YAG laser can be suppressed with sufficient pump power. It is experimentally confirmed that at absorbed powers higher than 6 W, the self-pulsing can be eliminated and a cw self-mode-locked pulse is generated instead of the Q-switched mode locking...
December 15, 2017: Optics Letters
Viktoryia Kazlouskaya, Paul M Sagerman, Gerald N Goldberg, Silvija P Gottesman
No abstract text is available yet for this article.
December 12, 2017: International Journal of Dermatology
Jari Nikkinen, Antti Härkönen, Mircea Guina
We report a monolithic 1240 nm diamond Raman laser producing pulses with duration of 42-62 ps at 100 kHz repetition rate, and maximum average power of 246 mW. The Raman laser is formed by a 0.5-mm thick planar diamond, coated on both sides and pumped by ~100 ps pulses from a Q-switched 1064 nm laser. The maximum conversion efficiency from 1064 nm to 1240 nm was about 25%. The 1240 nm signal was frequency-doubled in single-pass configuration through a 10-mm long LBO crystal, enabling generation of pulses with a duration of 29-46 ps at 620 nm...
November 27, 2017: Optics Express
Wenjing Tang, Jia Zhao, Tao Li, Kejian Yang, Shengzhi Zhao, Guiqiu Li, Dechun Li, Wenchao Qiao
In this Letter, a high-quality black phosphorus saturable absorber (BP-SA) with a multilayer structure was prepared, and its corresponding characteristics were investigated. Based on the BP-SA and an electro-optic modulator (EOM), a dual-loss-modulated mode-locked laser with a controllable repetition rate and high peak power was realized, which has the repetition rate of EOM and the mode-locking pulse width in the Q-switching and mode-locking laser. The output performances versus the pump power were measured...
December 1, 2017: Optics Letters
P Harshavardhan Reddy, A V Kir'yanov, Anirban Dhar, Shyamal Das, Debjit Dutta, Mrinmay Pal, Y O Barmenkov, J A Minguella-Gallardo, Shyamal Kumar Bhadra, Mukul Chandra Paul
We report the fabrication, characterization, and application (broadband supercontinuum [SC] generation) of ultra-high numerical-aperture heavily (50 mol. %) GeO2-doped optical fiber, obtained through a modified chemical vapor deposition process and rod-in-tube method. The formation of Ge-related diamagnetic defect centers, such as germanium oxygen defect centers (GeODC) with nonbridging lone electron pairs, confirmed by x-ray photoelectron spectroscopy and optical absorption studies, inducing hypolarizable local dipoles, may be responsible in boosting the nonlinear effects and enhancing stimulated Raman scattering at pumping with high-power pulses, culminating in generation of broadband SC generation...
November 20, 2017: Applied Optics
Yixuan Zhang, Chunqing Gao, Qing Wang, QuanXin Na, Mingwei Gao, Meng Zhang, Qing Ye, YuJia Wang, Jian Zhang
We demonstrate a 2090 nm single-frequency, high-energy, Q-switched Ho:YAG ceramic master oscillator and power amplifier system that contains two-stage amplifiers. The maximum single-frequency pulse energy is 55.64 mJ at a pulse repetition frequency of 200 Hz. The half-width of the pulse spectrum is measured to be 3.96 MHz by a heterodyne technique. To the best of our knowledge, 55.64 mJ is the highest single-frequency output energy obtained from the Ho:YAG laser.
December 1, 2017: Applied Optics
Ye Jin Lee, Ho Jeong Shin, Tai-Kyung Noh, Kwang-Ho Choi, Sung-Eun Chang
The picosecond lasers have shown to effectively treat tattoo pigments that are intractable to previous multiple Q-switched (QS) laser treatments. Therefore we hypothesized that a picosecond laser would show better efficacy with minimal adverse events in the treatment of melasma and post-inflammatory hyperpigmentation (PIH) that are difficult to treat with conventional QS lasers. Two patients with melasma and one patient with PIH were treated with a Picosecond 755-nm Alexandrite Laser (Cyanosure, USA). All patients were Korean with skin type IV and no longer responding to QS laser treatments...
December 2017: Annals of Dermatology
Alexander Baade, Claus von der Burchard, Meike Lawin, Stefan Koinzer, Benedikt Schmarbeck, Kerstin Schlott, Yoko Miura, Johann Roider, Reginald Birngruber, Ralf Brinkmann
Laser photocoagulation has been a treatment method for retinal diseases for decades. Recently, studies have demonstrated therapeutic benefits for subvisible effects. A treatment mode based on an automatic feedback algorithm to reliably generate subvisible and visible irradiations within a constant irradiation time is introduced. The method uses a site-individual adaptation of the laser power by monitoring the retinal temperature rise during the treatment using optoacoustics. This provides feedback to adjust the therapy laser power during the irradiation...
November 2017: Journal of Biomedical Optics
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