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87 results on '"Jia, Qingsong"'

5. An Application of 24Model to Analyse Capsizing of the Eastern Star Ferry

Author

Suo Xiao, Fu Gui, Wang Chunxue, and Jia Qingsong

Subjects
eastern star ferry accident, 24model, systematic accident causation model, accident analysis, hazards, Naval architecture. Shipbuilding. Marine engineering, VM1-989
Abstract

In the present study, the Eastern Star ferry accident was analyzed via 24Model. 24Model, as an accident causation model based on system thinking, holds that all causations of the accident are hazards and all hazards in the system need to be identified and comprehensively controlled in accident prevention. The result showed that five factors were the main causes of the accident. First, the direct causes: bad weather, the bad condition of the hull and the unsafe acts of the captain. Second, the indirect cause: the lack of safety awareness and safety knowledge of both the captain and the company’s senior management. Third, there were loopholes in safety management system, including the training, supervision and execution of the company. Forth, the root cause: the company didn’t establish a good safety culture. Last, the external causes: the severe market pressure, excessive regulatory authorities with puzzled relations and responsibilities-seriously hindered effective supervision. In order to prevent this kind of accident and to secure shipping system, the shipping companies and the relevant regulatory units should draw lessons from the five factors mentioned above, and take measures to identify and control those hazards.

Published
2017
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8. Mode-Locking Thulium-Doped Fiber Laser With 1.78-GHz Repetition Rate Based on Combination of Nonlinear Polarization Rotation and Semiconductor Saturable Absorber Mirror

Author

Jia Qingsong, Wang Tianshu, Ma Wanzhuo, Wang Zhen, Su Qingchao, Bo Baoxue, and Jiang Huilin

Subjects
Thulium-doped fiber laser, nonlinear polarization rotation, semiconductor saturable absorber mirror, harmonic mode-locking, high repetition rate., Applied optics. Photonics, TA1501-1820, Optics. Light, QC350-467
Abstract

We experimentally demonstrate a passively mode-locking thulium-doped fiber laser based on the combination of the nonlinear polarization rotation (NPR) and the semiconductor saturable absorber mirror (SESAM). In contrast to SESAM mode-locking merely, the fiber lasers based on NPR working together with SESAM have more advantages. By using two mode-locking mechanisms, the nonlinear effect can be enhanced tremendously; then, the threshold of high-order harmonic mode-locking (HML) pulse trains can be decreased, and the pulses width can be compressed. The shapes of the pulses can also be reshaped better, and the HML pulse trains stability can be improved. The high repetition rate of 1.78 GHz is obtained by both NPR and SESAM in the experiment. Because of the variation of the gain-and-loss distribution in the cavity, the output wavelength of mode-locking fiber laser can be tuned from 1839 to 1890 nm, and the multiwavelength HML is also observed in the experiment.

Published
2017
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13. Multi-wavelength noise-like pulsed erbium-doped fiber laser

Author

Jia Qingsong, Ma Wanzhuo, Zhao Desheng, Liu Runmin, Wang Furen, and Wang Tianshu

Subjects
Materials science, business.industry, Optoelectronics, Multi wavelength, business, Erbium doped fiber lasers, Atomic and Molecular Physics, and Optics, Noise (radio)
Published
2019

18. Mode-Locking Thulium-Doped Fiber Laser With 1.78-GHz Repetition Rate Based on Combination of Nonlinear Polarization Rotation and Semiconductor Saturable Absorber Mirror

Author

Wang Zhen, Bo Baoxue, Ma Wanzhuo, Jiang Huilin, Wang Tianshu, Su Qingchao, and Jia Qingsong

Subjects
lcsh:Applied optics. Photonics, Optical fiber, Materials science, harmonic mode-locking, 02 engineering and technology, 01 natural sciences, high repetition rate, Semiconductor laser theory, law.invention, 010309 optics, 020210 optoelectronics & photonics, Optics, law, Fiber laser, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, lcsh:QC350-467, semiconductor saturable absorber mirror, Electrical and Electronic Engineering, business.industry, Thulium-doped fiber laser, lcsh:TA1501-1820, Saturable absorption, Injection seeder, Q-switching, Atomic and Molecular Physics, and Optics, Mode-locking, Optoelectronics, nonlinear polarization rotation, business, lcsh:Optics. Light, Tunable laser
Abstract

We experimentally demonstrate a passively mode-locking thulium-doped fiber laser based on the combination of the nonlinear polarization rotation (NPR) and the semiconductor saturable absorber mirror (SESAM). In contrast to SESAM mode-locking merely, the fiber lasers based on NPR working together with SESAM have more advantages. By using two mode-locking mechanisms, the nonlinear effect can be enhanced tremendously; then, the threshold of high-order harmonic mode-locking (HML) pulse trains can be decreased, and the pulses width can be compressed. The shapes of the pulses can also be reshaped better, and the HML pulse trains stability can be improved. The high repetition rate of 1.78 GHz is obtained by both NPR and SESAM in the experiment. Because of the variation of the gain-and-loss distribution in the cavity, the output wavelength of mode-locking fiber laser can be tuned from 1839 to 1890 nm, and the multiwavelength HML is also observed in the experiment.

Published
2017

19. 复合滤波结构的窄线宽高频微波信号产生装置

Author

贾青松 Jia Qingsong, 徐丹锋 Xu Danfeng, 徐雨萌 Xu Yumeng, 雷昊 Lei Hao, and 刘建旭 Liu Jianxu

Subjects
Space and Planetary Science, Aerospace Engineering, Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics
Published
2021

20. Space laser communication system based on fiber laser phased array

Author

Ma Wanzhuo, Bi Mingzhe, Wang Tianshu, Ci Mingru, Jia Qingsong, Liu Xianzhu, Su Yuwei, and Liu Jingjiao

Subjects
Physics, Optics, business.industry, Phased array, Fiber laser, business, Space (mathematics), Atomic and Molecular Physics, and Optics, Free-space optical communication
Published
2016

21. Hybrid Transmission of Laser and Microwave Based on Dual-wavelength Brillouin Fiber Laser

Author

Wang Tianshu, Ma Wanzhuo, Jiang Huilin, Bo Baoxue, and Jia Qingsong

Subjects
Materials science, business.industry, Physics::Optics, Astrophysics::Cosmology and Extragalactic Astrophysics, Fresnel equations, Microwave transmission, Laser, law.invention, Transmission (telecommunications), law, Fiber laser, Optoelectronics, Optical circulator, Physics::Atomic Physics, business, Microwave, Free-space optical communication
Abstract

A laser and microwave hybrid transmission system based on dual-wavelength Brillouin fiber laser is proposed and demonstrated. Laser and microwave hybrid transmission is achieved through experimental analysis.

Published
2017

27. Multiwavelength tunable ring fiber laser operating at 1.9 μm

Author

Wan Chunming, Ma Wanzhuo, Gong Aihui, Jia Qingsong, Wang Tianshu, and Zhang Peng

Subjects
Optical fiber, Materials science, business.industry, Polarization-maintaining optical fiber, Condensed Matter Physics, Graded-index fiber, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Optics, Fiber Bragg grating, law, Fiber laser, Optoelectronics, Dispersion-shifted fiber, Electrical and Electronic Engineering, business, Plastic optical fiber, Photonic-crystal fiber
Abstract

A multiwavelength tunable fiber laser operating at 1.9 µm is demonstrated. A 4 m long Tm-doped single-mode fiber is pumped by a 1.57 µm fiber laser. A Sagnac fiber loop is used in the fiber laser cavity as a tunable filter, and the fiber loop consists of a 3-dB coupler, a polarization controller (PC), and a segment of polarization-maintaining fiber. Adjusting the PC state and pump power, multiwavelength laser with wavelength spacing of 2.5 nm 1895–1915 nm is observed. The number of output wavelength can be tuned precisely from one to four by adjusting the PC state. The 3-dB linewidth and side-mode suppression ratio are 0.045 nm and 45 dB, respectively. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:401–403, 2015

Published
2014

28. All-fiber laser generating at 3.8 μm pumped by 1565 nm fiber laser and the second-order laser at 1.9 μm

Author

Jiang Huilin, Zhang Peng, Wei Yizhen, Hu Kai, Jia Qingsong, and Wang Tianshu

Subjects
Distributed feedback laser, Active laser medium, Materials science, Laser diode, business.industry, Condensed Matter Physics, Laser, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Vertical-cavity surface-emitting laser, law.invention, Optics, law, Fiber laser, Dispersion-shifted fiber, Laser power scaling, Electrical and Electronic Engineering, business
Abstract

We propose an all-fiber source at 3.8 μm with a high Tm-doped fiber as the gain medium pumped by a 1565-nm high-power fiber laser. With a laser diode at 1565 nm amplified by a high power erbium-doped fiber amplifier injecting into a segment of Tm-doped fiber, a fiber laser at 3.8 μm generates. Simultaneously, a second-order laser at 1.9 μm (dual-frequency of 3.8 μm) can be observed clearly. The laser has a threshold pump power of ∼300 mW and generates more than 176 mW continuous-wave output power with 1560 mW pump power. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:848–850, 2014

Published
2014

39. Raman Gain Spectrum in 1.70 μm Band Pumped by Multimode Laser

Author

Zhang Peng, Wu Di, Jia Qingsong, and Du Quanli

Subjects
Fiber diameter, Materials science, business.industry, Spectrum (functional analysis), Optoelectronics, Electrical and Electronic Engineering, business, Raman gain, Atomic and Molecular Physics, and Optics
Published
2017

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