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q switched laser

M K Trivedi, F C Yang, B K Cho
Melasma is a dysregulation of the homeostatic mechanisms that control skin pigmentation and excess pigment is produced. Traditional treatment approaches with topical medications and chemical peels are commonly used but due to the refractory and recurrent nature of melasma, patients often seek alternative treatment strategies such as laser and light therapy. Several types of laser and light therapy have been studied in the treatment of melasma. Intense pulsed light, low fluence Q-switched lasers, and non-ablative fractionated lasers are the most common lasers and light treatments that are currently performed...
March 2017: International Journal of Women's Dermatology
Daniel P Friedmann, Sara Buckley, Vineet Mishra
No abstract text is available yet for this article.
April 28, 2017: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
Nada Abusalah Almabrouk Imrigha, Noriah Bidin, Pik Suan Lau, Nurfatin Musa, Nurlaily Zakaria, Ganesan Krishnan
Q-switched Nd: YAG laser is the most effective laser for tattoo removal. Photobiomodulation (PBM) therapy is an alternative method applied to accelerate the wound healing. This paper investigated the effects of PBM therapy using 808 nm diode laser on tattooed skin after laser tattoo removal. Forty-five rats were selected and tattooed with black ink on their dorsal, and then distributed into three groups. G0 was received non-laser irradiation. G1 was treated by laser tattoo removal using 1064 nm with energy density of 3...
May 2, 2017: Journal of Biophotonics
H Ahmad, S A Reduan, A Z Zulkifli, Z C Tiu
A tunable passively Q-switched for S+/S band thulium-fluoride fiber (TFF) laser using single-walled carbon nanotubes as a saturable absorber is proposed and demonstrated. The tunability of the proposed laser covers a wavelength region of 1450.0-1512.0 nm, with a range of 62.0 nm. Stable Q-switched operation can be obtained at a pump power of 115.7-229.9 mW at 1492.0 nm. The resulting pulses have a measured repetition rate and pulse width of 12.0-36.4 kHz and 6.2-3.6 μs, respectively. The maximum pulse energy that was achieved in this experiment is 122...
May 1, 2017: Applied Optics
Usha Chakravarty, P K Mukhopadhyay, A Kuruvilla, B N Upadhyaya, K S Bindra
A narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using an acousto-optic modulator and multimode interference filter (MMIF) in the linear bulk cavity resonator and an all-fiber ring cavity resonator has been demonstrated. Insertion of an MMIF in the linear cavity resonator using bulk components decreased the spectral bandwidth of the Q-switched signal by two orders of magnitude from 11 to less than 0.1 nm. Spectral tunability of more than 16 nm in the range from 1057 to 1073 nm has also been achieved by the combination of MMIF and a standard polarization controller (SPC)...
May 1, 2017: Applied Optics
Ferda Canbaz, Ismail Yorulmaz, Alphan Sennaroglu
We report, what is to our knowledge, the first passively Q-switched operation of a 2.3-μm Tm<sup>3+</sup>:YLF laser by using a Cr<sup>2+</sup>:ZnSe saturable absorber. In the experiments, a tunable Ti<sup>3+</sup>:sapphire laser was used to end pump the Tm<sup>3+</sup>:YLF gain medium inside an x cavity. A Cr<sup>2+</sup>:ZnSe saturable absorber was also included in the cavity to initiate passive Q switching. At all pump power levels above lasing threshold, passively Q-switched operation of the Tm<sup>3+</sup>:YLF laser could be obtained at 2309 nm with pulse durations and repetition frequencies in the ranges of 1...
May 1, 2017: Optics Letters
Abdul Khaleque, Evgeny G Mironov, Jonas H Osório, Ziyuan Li, Cristiano M B Cordeiro, Liming Liu, Marcos A R Franco, Jong-Leng Liow, Haroldo T Hattori
In this article, a new and flexible approach to control the electric field enhancement of bow-tie nano-antennas by integrating them on the lateral of a tapered optical fiber is proposed. The device is driven by a Q-switched laser and the performance of a fabricated nano-antenna in a quartz slide is tested by a Surface Enhanced Raman Scattering (SERS) experiment. A refractive index sensing experiment is also performed and a sensitivity of (240 ± 30) nm/RIU is found in the 1.33-1.35 index range.
April 17, 2017: Optics Express
Tianxing Wang, Zhijun Yan, Chengbo Mou, Kaiming Zhou, Lin Zhang
Nanosecond passive Q-switching generation from an all-fiber erbium-doped laser with a UV inscribed 45° tilted fiber grating (TFG) is systematically demonstrated. The 45° TFG is employed as a polarizer together with two polarization controllers (PCs) to realize nonlinear polarization rotation (NPR). Because of the NPR effect, stable Q-switched pulses with an average output power of 17.5 mW, a single pulse energy of 72.7 nJ, a repetition rate of 241 kHz, a pulse width of 466 ns, and a signal to noise ratio (SNR) of 58...
April 20, 2017: Applied Optics
Jae-Hui Nam, Joon Hong Min, Wang-Kyun Kim, Sunmin Yim, Won-Serk Kim
A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, or laser toning, has yielded favorable outcomes in various benign pigmented disorders. However, the exact mechanism of action of laser toning has not been fully elucidated. We sought to determine the inhibitory effect of laser toning on melanogenesis and to assess how laser passes influence the outcomes. To produce perceptible pigmentation, nine HRM-2 melanin-possessing hairless mice were treated with ultraviolet (UV) B radiation on the dorsal skin...
April 20, 2017: Lasers in Medical Science
Jie Lin, Li Jing, Hao Zhu, Fu-Sheng Dong
The aim of the study was to determine the mechanism of action of the 800 nm semiconductor laser on skin blackheads and coarse pores. A total of 24 healthy purebred short-haired male guinea pigs, weighing 350-400 g, were selected and smeared with 0.5 ml coal tar suspension evenly by injector once daily. Treatment was continued for 14 days to form an experimental area of 8×3 cm on the back of the guinea pigs. The animals were divided into the following groups: Normal control group (NC), low-dose laser treatment group (L-LS), high-dose laser treatment group (H-LS), and Q-switched Nd:YAG treatment group (QC)...
January 2017: Experimental and Therapeutic Medicine
Paul J D Whiteside, Chenxi Qian, Nicholas Golda, Heather K Hunt
BACKGROUND AND OBJECTIVE: Applications of light-based energy devices involving optical targets within the dermis frequently experience negative side-effects resultant from surface scattering and excess optical absorption by epidermal melanin. As a broadband optical absorber, melanin decreases the efficacy of light-based treatments throughout the ultraviolet, visible, and near-infrared spectra while also generating additional heat within the surface tissue that can lead to inflammation or tissue damage...
April 18, 2017: Lasers in Surgery and Medicine
Xinlu Zhang, Yong Luo, Tianhan Wang, Junfeng Dai, Jianxin Zhang, Jiang Li, Jinhui Cui, Jinjer Huang
We first report on a diode-end-pumped passively Q-switched mode-locking Tm,Ho:LLF laser at 2053 nm by using a Cr:ZnS saturable absorber. A stable Q-switched mode-locking pulse train with a nearly 100% modulation depth was achieved. The repetition frequency of the Q-switched pulse envelope increased from 0.5 to 12.3 kHz with increasing pump power from 1 to 4.36 W. The maximum average output power of 145 mW was obtained, and the width of the mode-locked pulse was estimated to be less than 682 ps with a 250 MHz repetition frequency within a Q-switched pulse envelope of about 700 ns...
April 10, 2017: Applied Optics
Alireza Moosakhani, Parviz Parvin, Seyedeh Zahra Mortazavi, Ali Reyhani, Shariar Abachi
The Q-switched Nd:YAG laser is focused on a palladium target in the control chamber filled with various hydrocarbon atmospheres (C1-C4) to investigate their effect on the palladium ablated mass, gas reaction products, and corresponding plasma parameters (such as electron density N<sub>e</sub> and plasma temperature T<sub>e</sub>) during molecular decomposition. The plasma parameters arise mainly from the Pd nanocatalytic activity during the laser-induced plasma process. We compare synthetic air atmosphere to hydrocarbon media to understand how the latter generates excess heat via oxygen-free exothermic (recombination) reactions...
April 10, 2017: Applied Optics
Mithila Vanarase, Ram Krishan Gautam, Pooja Arora, Sonali Bajaj, Neha Meena, Ananta Khurana
BACKGROUND: Q-switched lasers are conventionally used for the treatment of black tattoo. However they require multiple sittings and the response may be slow due to competing epidermal pigment in dark skin. OBJECTIVE: To compare the efficacy of Q Switched Nd:YAG laser alone with its combination with ultrapulse CO2 in black tattoo removal. MATERIALS AND METHODS: Sixty patients of black tattoo were randomized into two groups. Group A was treated with QS Nd:YAG laser (1064 nm) alone and group B received combination of ablative ultrapulse CO2 followed by fixed dose QS Nd:YAG laser (1064 nm), at 6 weeks interval for a maximum of 6 sittings...
April 10, 2017: Journal of Cosmetic and Laser Therapy: Official Publication of the European Society for Laser Dermatology
Hyeong-Rae Kim, Jung-Min Shin, Jin-Hyup Lee, Hae-Eul Lee, Myung Im, Young Lee, Chang-Deok Kim, Young-Joon Seo, Jeung-Hoon Lee
No abstract text is available yet for this article.
April 2017: Annals of Dermatology
Rongfei Wei, Tian Qiao, Xiangling Tian, Hang Zhang, Xin He, Zhongliang Hu, Qiuqun Chen, Jianrong Qiu
An enhanced nonlinear optical (NLO) performance was observed in Se-doped MoS2 nanosheets synthesized through a facile annealing process. Se-doped MoS2 nanosheets with a large saturable intensity and high modulation depth generated stable passively Q-switched fiber laser pulses at 1559 nm. In comparison with the Q-switched fiber laser utilizing the pristine MoS2 nanosheets as a saturable absorber, the passive Q-switching operation based on Se-doped MoS2 nanosheets could be conducted at a lower threshold power of 50 mW, a wider range of repetition rates from 28...
May 26, 2017: Nanotechnology
Weijie Nie, Rang Li, Chen Cheng, Yanxue Chen, Qingming Lu, Carolina Romero, Javier R Vázquez de Aldana, Xiaotao Hao, Feng Chen
We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66...
April 6, 2017: Scientific Reports
Arvydas Kausas, Pascal Loiseau, Gerard Aka, Yanqing Zheng, Lihe Zheng, Takunori Taira
In this work the performance of two yttrium calcium oxyborate (YCOB) crystals made by Czochralski and Bridgman growth process was measured. By using high peak power, passively Q-switched Nd<sup>3+</sup>:YAG/Cr<sup>4+</sup>:YAG microlaser, high conversion second harmonic generation efficiency were obtained. Laser pulses at 532 nm with 1.14 mJ energy and 223 ps duration were obtained with a 15-mm long YCOB crystal that was grown by Bridgman method. The conversion efficiency was 70.2%, comparable with the conversion efficiency of 72...
March 20, 2017: Optics Express
Huan Liu, Zhe Sun, Xi Wang, Yonggang Wang, Guanghua Cheng
Graphene-like two-dimensional (2D) materials have shown remarkable broadband saturable absorption properties. These materials were successfully applied into mode locked lasers to generate laser pulses with the pulse duration from picosecond to femtosecond. However, these novel materials have not shown good performance as far in another important aspect: Q-switched lasers. Solid-state or fiber lasers Q-switched with broadband absorbers usually generated pulses of one hundred nanosecond to several microsecond, which show weak competitiveness compared to traditional absorbers such as Cr: YAG and semiconductor saturable absorption mirror (SESAM)...
March 20, 2017: Optics Express
Chen Cheng, Ziqi Li, Ningning Dong, Jun Wang, Feng Chen
The nonlinear optical responses of two-dimensional (2D) few-layer tin diselenide (SnSe<sub>2</sub>) have been investigated in this work. By applying the Z-scan technique, the saturable absorption of SnSe<sub>2</sub> thin film has been observed at a wavelength of ~1μm, which enables SnSe<sub>2,</sub> a new saturable absorber for pulsed laser generation. A detailed exploration of the nonlinear absorption of SnSe<sub>2</sub> film and their dependence on excitation pulse energy is carried out...
March 20, 2017: Optics Express
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