50 results on '"Qingsong, Jia"'
Search Results
2. Accident causes data-driven coal and gas outburst accidents prevention: Application of data mining and machine learning in accident path mining and accident case-based deduction
- Author
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Xuecai, Xie, Xueming, Shu, Gui, Fu, Shifei, Shen, Qingsong, Jia, Jun, Hu, and Zhirong, Wu
- Published
- 2022
- Full Text
- View/download PDF
3. Method Construction and Evaluation: A More Comprehensive and Reliable Classification of Coal Mine Gas Explosion Causes
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Qingsong Jia, Gui Fu, Xuecai Xie, and Shihan Hu
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coal mine gas explosion ,accident cause classification ,consistency ,validity ,24Model ,Technology - Abstract
Coal is an important fossil fuel energy that occupies a high position in the energy use of China and even the world. However, gas explosions are still the deadliest coal mine accident in China, which has long plagued the safety of energy mining. Only through accident cause analysis can we know the exact cause of the accident so as to make targeted policies, safety trainings, etc. However, the lack of detailed accident cause classification in current coal mine gas explosion accidents affects the comprehensiveness and accuracy of energy mining safety strategies. Therefore, in this study, a classification method for coal mine gas explosion accident causes based on the sixth edition 24Model and the three-element classification of gas explosions was proposed. Then, the consistency and validity of the newly established classification system were evaluated based on the three indicators, i.e., observer consistency, content validity, and criterion validity, and the performance of the classification system was verified. The results showed that the classification method exhibits good consistency and validity, and, compared with other classification methods, it can significantly improve the comprehensiveness of accident cause analysis results so as to obtain a more scientific energy mining safety strategy. In addition, the process used in this study to construct the classification and evaluate the performance of the classification is transferable, and it can provide a reference for the construction and evaluation of accident cause classifications in other fields.
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- 2022
- Full Text
- View/download PDF
4. An Experimental Hybrid RF/FSO System Using Optical Heterodyne Method.
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Ziqi Jiang, Zhiwen Sun, Qingsong Jia, Junda Chen, Xinmeng Zhang, Tianshu Wang, Chunyi Chen, and Zhi Liu
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- 2018
- Full Text
- View/download PDF
5. Wavelength-Spacing Switchable Dual-Wavelength Single Longitudinal Mode Thulium-Doped Fiber Laser at 1.9 μm
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Wanzhuo Ma, Tianshu Wang, Yuwei Su, Yan Zhang, Peng Liu, Qingsong Jia, Peng Zhang, and Huilin Jiang
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Fiber laser ,dual-wavelength laser ,stability ,single longitudinal mode ,Applied optics. Photonics ,TA1501-1820 ,Optics. Light ,QC350-467 - Abstract
We propose and demonstrate a spacing switchable dual-wavelength single longitudinal mode thulium-doped fiber laser at 1.9 μm. The fiber laser employs a ring cavity and a segment of 4-m thulium-doped fiber pumped by a 1563 nm laser. A fiber Sagnac loop is used as a comb filter to generate a stable dual-wavelength laser. A multimode interference filter consisting of a single-mode-multimode-single-mode fiber and a rotary fiber squeezer is used to adjust the wavelength spacing. When pump power is fixed at 260 mW, a stable dual-wavelength laser at 1.9 μm is obtained by adjusting the polarization controller in the Sagnac filter, and the wavelength spacing can be tuned from 6.7 to 26.7 nm by adjusting the rotary fiber squeezer in the multimode interference filter. Each wavelength of the dual-wavelength laser operates at a single longitudinal mode state, and the maximum linewidth is 7.5 MHz analyzed by a Fabry-Perot scanning interferometer.
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- 2016
- Full Text
- View/download PDF
6. The development history of accident causation models in the past 100 years: 24Model, a more modern accident causation model
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Gui Fu, Xuecai Xie, Ying Ge, Qingsong Jia, Ping Chen, and Zonghan Li
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021110 strategic, defence & security studies ,Environmental Engineering ,Actuarial science ,General Chemical Engineering ,0211 other engineering and technologies ,02 engineering and technology ,Accident analysis ,010501 environmental sciences ,01 natural sciences ,Accident (fallacy) ,Qualitative analysis ,Quantitative analysis (finance) ,Environmental Chemistry ,Safety culture ,Safety management systems ,Causation ,Safety, Risk, Reliability and Quality ,Psychology ,0105 earth and related environmental sciences ,Causal model - Abstract
Accident causation models mainly answer the following two questions: (ⅰ) why does an accident occur, and (ⅱ) how does it occur? These models are the most important theoretical basis for safety science, and provide an important method for accident analysis and prevention. To understand accident causation models systematically and comprehensively, this work clarifies the development history of these models over the past 100 years. The work conducted in this study is summarised as follows: (i) The role and origin of accident causation models are introduced. (ii) A new method for classifying accident causation models is proposed. The method divides the accident causal models into linear and nonlinear accident causation models, and the latter are further divided into human-based, statistics-based, energy-based, and system-based accident models. (iii) A review of 29 representative accident causation models proposed in the past 100 years is conducted. The theoretical basis, application flow, and application status of these models are highlighted. (iv) A detailed introduction to the 24Model, an accident causation model with theoretical innovation and more modern safety management, is presented. (v) A comparative analysis of various accident causation models and their development trends are discussed. (vi) This safety also summarises the application status of the accident causal model and prospects for future applications. The research findings of this study are as follows: (i) The newly proposed classification method of accident causation models clarifies the classification of accident causes. (ii) Each type of accident causation model has its own characteristics and application scope. In an accident analysis, an accident model that meets its industry characteristics should be selected. (iii) ‘Organisational factors’ will be replaced by more modern ‘safety management systems’, and people will pay more attention to the role of ‘safety culture’ in accident prevention. Accident causation models will develop in a linear and systematic way. (iv) The current accident causation models consist mainly of qualitative analysis and quantitative analysis, and will develop in the direction of dynamic analysis, accident prediction, and intelligent comprehensive analysis in the future.
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- 2020
7. Accidents analysis and prevention of coal and gas outburst: Understanding human errors in accidents
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Gui Fu, Wenqing Tong, Ying Ge, Xuecai Xie, and Qingsong Jia
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021110 strategic, defence & security studies ,Environmental Engineering ,business.industry ,General Chemical Engineering ,Human error ,0211 other engineering and technologies ,Coal mining ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Falling (accident) ,Work (electrical) ,Management system ,medicine ,Forensic engineering ,Environmental Chemistry ,Environmental science ,Coal ,Safety culture ,medicine.symptom ,Safety, Risk, Reliability and Quality ,business ,0105 earth and related environmental sciences ,Case analysis - Abstract
Coal is an important energy resource internationally. However, accidents have severely restricted the clean and safe production of coal resources. Among such accidents, coal and gas outburst accidents are a kind of coalmine disaster with high destructive power. Previous research on coal and gas outburst accidents mainly focused on gas factors but ignored the role of human factors. This paper analyses the coal and gas outburst accidents in China from 2008 to 2018 and studies its macroscopic laws. To better understand the causes of coal and gas outbursts, this paper uses the 24modelel to analyse coal and gas accidents and suggest measures for accident prevention from the two aspects ‘gas’ (risk control) and ‘humans’ (behavioural safety). Macroscopic law research found the following: (1) March, May, July, and August are the predominant months for accidents. (2) The second to fourth hours of the working hours and the first hour before the end of work are the peak periods for accidents. (3) Guizhou, Hunan, Henan, Sichuan, Yunnan, and Chongqing are the provinces with the most coal and gas outburst accidents. (4) An overall 75.82 % of accidents occurred in the driving face, and 81.08 % of accidents occurred in coal and gas outburst mines. (5) Blasting, drilling, driving, and coal falling are the main inducing factors. Case analysis of accidents found the following: (1) Human error is the leading cause of accidents. Among the errors, the lack of strict enforcement of outburst prevention measures, illegal command, and the illegal operation of miners are the main unsafe acts. (2) Safety knowledge and awareness of miners is not generally high, and serious habitual violations and unsafe psychologies exist. (3) The gas comprehensive prevention system and supervision system in the coal mine safety management system (SMS) can be easily operated improperly, and the safety training system and emergency management system can be absent. (4) Coalmine enterprises seriously lack safety culture.
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- 2020
8. Comparison of the theoretical elements and application characteristics of STAMP, FRAM, and 24Model: A major hazardous chemical explosion accident
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Yali Wu, Gui Fu, Meng Han, Qingsong Jia, Qian Lyu, Yuxin Wang, and Zhirong Wu
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Control and Systems Engineering ,General Chemical Engineering ,Energy Engineering and Power Technology ,Management Science and Operations Research ,Safety, Risk, Reliability and Quality ,Industrial and Manufacturing Engineering ,Food Science - Published
- 2022
9. Study on the reliability of accident analysis results: Taking two groups of four accident analysis references with the 24Model as samples
- Author
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Qingsong Jia, Gui Fu, Xuecai Xie, Shihan Hu, Yuxin Wang, and Qian Lyu
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Safety, Risk, Reliability and Quality - Abstract
Accident prevention depends on accident analysis. In order to improve the reliability of accident analysis and find the common problems related to reliability in accident analysis, two groups of four papers of master’s and doctor’s theses which applied 24Model to analysis coal mine gas explosion accident were selected as samples. The unsafe act results obtained from the analysis are compared. The results show a low consistency level, which reflects that the reliability of the output needs to be improved. Through analysis, the inconsistency of details in causes description, the difficulty in the cause description and the omission of unsafe acts are the main reasons leading to the above situation. In order to standardize the description of cause items, the components of unsafe acts were defined as “premise + action”, and seven types of premises were summarized to judge unsafe acts. In order to improve the efficiency and reliability of accident analysis, it is suggested that the current data should be taken as reference, and the taxonomy based on consequences should be established to unify unsafe act detail description level, and the corresponding computer software should be developed to assist accident analysis.
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- 2022
10. High repetition-rate passively mode-locking Tm-doped fiber laser based on narrow bandwidth filtering
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Chengbo Wang, Tianshu Wang, Furen Wang, Wanzhuo Ma, Runmin Liu, Desheng Zhao, and Qingsong Jia
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Materials science ,business.industry ,Bandwidth (signal processing) ,02 engineering and technology ,Filter (signal processing) ,Fundamental frequency ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,010309 optics ,Wavelength ,020210 optoelectronics & photonics ,Optics ,Mode-locking ,Control and Systems Engineering ,law ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,business ,Instrumentation ,Pulse-width modulation - Abstract
We propose and demonstrate a high repetition-rate passively mode-locking Tm-doped fiber laser. Mode-locking operation is achieved by using a conventional nonlinear polarization rotation (NPR) structure. Fundamental frequency soliton laser is obtained with the repetition-rate of 5.05 MHz and the pulse width of 54.7 ps. 3-dB bandwidth and signal and noise ratio (SNR) are 3.1 nm and 53.03 dB, respectively. In order to improve repetition-rate of the mode-locking pulse, a narrow band filter is adopted. In this case, maximum repetition-rate of the output pulse can be up to 7.75 GHz (1534 orders). Pulse width and 3-dB bandwidth of mode-locking laser are compressed to 67.2 ps and 0.2 nm, respectively, and SNR is 19.71 dB. In addition, the laser center wavelength can be tuned from 1882 nm to 1925 nm by adjusting the filter.
- Published
- 2019
11. Passively Mode-Locked Fiber Lasers Based on Nonlinearity at 2-μm Band
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Peng Liu, Tianshu Wang, Qingsong Jia, Wanzhuo Ma, Qingchao Su, and Peng Zhang
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Birefringence ,Materials science ,business.industry ,Physics::Optics ,Saturable absorption ,02 engineering and technology ,Polarization (waves) ,Laser ,Lyot filter ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,law.invention ,010309 optics ,020210 optoelectronics & photonics ,Optics ,law ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,business ,Comb filter ,Pulse-width modulation - Abstract
2- μ m fiber lasers are of wide potential applications in the fields of radar, sensing, and free-space communications. We introduced a simple approach to generate passively mode-locked pulse in thulium-doped fiber lasers based on nonlinear polarization rotation (NPR) in our previous work. The high repetition rate of 1.78 GHz is obtained by both NPR and semiconductor saturable absorption mirror. By using a polarization-maintaining fiber in the experiment, a birefringence Lyot filter as a fiber comb filter can be constructed, and then the tuning range of 94 nm can be obtained for the mode-locked laser. In this paper, we also demonstrated our recent research work, a square-wave mode-locked fiber laser at 2- μ m band based on nonlinear amplifying loop mirror. The square-wave noiselike pulse (NLP) at longer wavelength of 2- μ m band can be observed. With the increase of the pump power, pulse width can be increased from 0.75 to 1.3 ns. The polarization vector characteristics of the square-wave NLP were analyzed experimentally. In addition, with the increase of the pump power, a kind of square-wave mode-locked pulse with low-intensity multipulse bunches can be observed, and these multipulse bunches can be operated at the multipulse mode-locked state. The side-mode suppression ratio decreased from 50 to 30 dB.
- Published
- 2018
12. An Application of 24Model to Analyse Capsizing of the Eastern Star Ferry
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Gui Fu, Qingsong Jia, Chunxue Wang, and Xiao Suo
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050210 logistics & transportation ,021110 strategic, defence & security studies ,Engineering ,systematic accident causation model ,business.industry ,Mechanical Engineering ,eastern star ferry accident ,05 social sciences ,Naval architecture. Shipbuilding. Marine engineering ,0211 other engineering and technologies ,24model ,VM1-989 ,Ocean Engineering ,02 engineering and technology ,Accident analysis ,Star (graph theory) ,Capsizing ,accident analysis ,0502 economics and business ,business ,hazards ,Seismology - 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
13. Tunable multiwavelength Brillouin-Raman fiber laser in a linear cavity with spectrum reshaped by Rayleigh scattering
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Qingsong Jia, Wanzhuo Ma, Peng Zhang, Zhen Wang, Tianshu Wang, and Qingchao Su
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Materials science ,02 engineering and technology ,01 natural sciences ,010309 optics ,symbols.namesake ,020210 optoelectronics & photonics ,Optics ,Double-clad fiber ,Brillouin scattering ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Dispersion-shifted fiber ,Laser power scaling ,Electrical and Electronic Engineering ,Rayleigh scattering ,Instrumentation ,business.industry ,Single-mode optical fiber ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Control and Systems Engineering ,symbols ,Optoelectronics ,Optical circulator ,business - Abstract
In this paper, we propose and experimentally study a simple linear cavity multiwavelength Brillouin-Raman fiber laser (MBRFL). The fiber feedback loop which consists of an optical circulator is placed at the end of the dispersion compensating fiber (DCF) to enhance the reflectivity of the Brillouin Stokes waves. As a result, 245 Brillouin Stokes lines with 0.072 nm channel-spacing are generated across the wavelength range of 18.6 nm from 1544.98 to 1563.58 nm when Brillouin pump (BP) is fixed to 1545 nm/−2.94 dBm and a single Raman pump (RP) laser power is set to 718 mW. The output spectrum is reshaped based on Rayleigh scattering by adding 45 km single mode fiber (SMF) in the cavity. The average optical signal to noise ratio (OSNR) about 18 dB has been measured in this structure. A tunable multiwavelength range of 20 nm from 1545 to 1565 nm is obtained. We also demonstrate the influence of BP wavelength and power on MBRFL.
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- 2017
14. Multi-wavelength noise-like pulsed erbium-doped fiber laser
- Author
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Furen, WANG, primary, Tianshu, WANG, additional, Wanzhuo, MA, additional, Qingsong, JIA, additional, Desheng, ZHAO, additional, and Runmin, LIU, additional
- Published
- 2019
- Full Text
- View/download PDF
15. Dual square-wave pulse passively mode-locked fiber laser
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Peng Liu, Tianshu Wang, Yuwei Su, Jing Zhang, Wanzhuo Ma, Qingchao Su, and Qingsong Jia
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Materials science ,business.industry ,Materials Science (miscellaneous) ,Physics::Optics ,Pulse duration ,02 engineering and technology ,Square wave ,01 natural sciences ,Industrial and Manufacturing Engineering ,Power (physics) ,Pulse (physics) ,010309 optics ,020210 optoelectronics & photonics ,Optics ,Mode-locking ,Fiber laser ,0103 physical sciences ,Dispersion (optics) ,0202 electrical engineering, electronic engineering, information engineering ,Business and International Management ,business ,Free-space optical communication - Abstract
We study a passively mode-locked square-wave pulse (SWP) fiber laser with a nonlinear amplifying loop mirror in the cavity. The net dispersion of the cavity is about 0.68 ps2 and the SWP mode-locked fiber laser can be realized. The peak power of the SWP hardly varies and the pulse duration gets expanded with the increasing pump power. SWPs breaking in the low nonlinear cavity can be observed and the stable dual SWP can be achieved in the experiment. When the total pump power stays at 800 mW, the interval of dual pulses is 41 ns. The widths of dual SWPs are both 1.5 ns. The output power rises linearly with the increasing of the pump power, while the interval of dual SWPs is almost constant. Then, the physical mechanism of the SWP breaking and vector nature of the pulse are analyzed.
- Published
- 2017
16. 40 GHz narrow linewidth frequency-switched microwave signal generation based on a single-longitudinal-mode double-Brillouin-frequency spaced Brillouin fiber laser
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Tianshu Wang, Baoxue Bo, Xiaoyan Li, Qingsong Jia, and Peng Zhang
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Materials science ,Materials Science (miscellaneous) ,Frequency drift ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,Industrial and Manufacturing Engineering ,law.invention ,010309 optics ,Longitudinal mode ,Laser linewidth ,020210 optoelectronics & photonics ,Optics ,Fiber Bragg grating ,law ,Brillouin scattering ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Physics::Atomic Physics ,Business and International Management ,business.industry ,Laser ,Optoelectronics ,business ,Microwave - Abstract
A novel approach to generating 40 GHz narrow linewidth frequency-switched microwave signals is proposed and demonstrated. In this scheme, a single-longitudinal-mode (SLM) double-Brillouin-frequency spaced Brillouin fiber laser with dual-ring configuration and unpumped erbium-doped fiber (EDF) is used to generate dual-wavelength lasers, and a fiber Bragg grating is used to select the laser for different Brillouin frequency spacings. Dual-ring configuration and unpumped EDF are designed to select the mode for the SLM laser. Dual-wavelength lasers are inserted into a photodetector, and microwave signals at 10.66, 21.39, 32.12, or 42.85 GHz can be obtained. The linewidth of the generated microwave signals is less than 69 kHz. The frequency drift at each frequency is less than 0.83 MHz. The frequency noise and linewidth of Stokes signals are measured, and the linewidth broadening effect of microwave signals is analyzed.
- Published
- 2017
17. Multi-wavelength narrow linewidth thulium-doped fiber laser operating at 1.9μm using a tunable Sagnac fiber period filter
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Wanzhuo Ma, Jiang Huilin, Jing Zhang, Qingsong Jia, Tianshu Wang, and Peng Zhang
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Distributed feedback laser ,Materials science ,business.industry ,Physics::Optics ,Polarization-maintaining optical fiber ,Atomic and Molecular Physics, and Optics ,Laser linewidth ,Optics ,Fiber Bragg grating ,Fiber laser ,Optoelectronics ,Dispersion-shifted fiber ,Physics::Atomic Physics ,Laser power scaling ,business ,Tunable laser - Abstract
We demonstrate a tunable multi-wavelength thulium-doped fiber laser (TDFL). A Sagnac fiber period filter is employed to achieve the tunable multi-wavelength fiber laser and consists of a 3-dB coupler, a segment of 4 m long polarization maintained thulium-doped fiber (PM-TDF) and a polarization controller (PC). Multi-wavelength laser are observed in the wavelength region of 1.9 μm, and the side-mode suppression ratio (SMSR) of the multi-wavelength fiber laser is over 55 dB with 1 W pump power at 1.56 μm. By adjusting PC, tunable range of output laser spectrum from 1955 to 1962 nm can be obtained with single-wavelength laser. In addition, the linewidth of the laser is narrower due to the use of a fiber loop for suppressing multimode oscillation. This fiber laser around 1.9 μm wavelength are useful mid-infrared laser generation, free space laser communications, medicine and biomedical, coherent laser radar for remote atmospheric sensing, pump for nonlinear frequency conversion based on soliton self-frequency shift and second-harmonic generation.
- Published
- 2015
18. Pulse width compression of supercontinuum based on free space OTDM system
- Author
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Dashuai Wang, Qingsong Jia, Wanzhuo Ma, Peng Lin, Junda Chen, Tianshu Wang, Xinmeng Zhang, and Peng Zhang
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Materials science ,Optical fiber ,business.industry ,Physics::Optics ,02 engineering and technology ,Free space ,Laser ,Compression (physics) ,Supercontinuum ,law.invention ,Power (physics) ,020210 optoelectronics & photonics ,Optics ,Nonlinear fiber ,law ,0202 electrical engineering, electronic engineering, information engineering ,business ,Pulse-width modulation - Abstract
In this paper, a pulse width compression scheme for optical time division multiplexing (OTDM) system based on supercontinuum (SC) is proposed. After injecting a high power narrow line-width pulse width laser into high nonlinear fiber (HNLF), the pulse width has been obviously narrowed. This demonstration suggests that the pulse width compression effect of SC could be used in free-space OTDM system.
- Published
- 2017
19. Free-space broad-spectrum optical communication based on supercontinuum
- Author
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Wanzhuo Ma, Qingsong Jia, Junda Chen, Peng Lin, Tianshu Wang, Dashuai Wang, Peng Zhang, and Xinmeng Zhang
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Physics ,Optical fiber ,business.industry ,05 social sciences ,Optical communication ,Physics::Optics ,050801 communication & media studies ,020206 networking & telecommunications ,Adaptive equalizer ,02 engineering and technology ,Communications system ,Noise (electronics) ,Optical switch ,Supercontinuum ,law.invention ,0508 media and communications ,Optics ,Interference (communication) ,law ,0202 electrical engineering, electronic engineering, information engineering ,business - Abstract
In this paper, a free-space optical (FSO) communication system with supercontinuum source generated by dispersion shift fiber (DSF) from pulsed light modulated by optical switches is designed and constructed. In addition, the experimental results of free-space optical communication between broadband and narrowband light source are compared. Verifying the feasibility of broad-spectrum FSO communication link through atmospheric turbulence can be achieved by reducing the inter-symbol interference caused by excessive noise with addition of adaptive equalizer. The experimental results show that the super continuum can be used as the optical signal carrier, and the signal can be wirelessly transmitted under the space atmospheric channel condition.
- Published
- 2017
20. Widely tunable 2 μm continuous-wave and mode-locked fiber laser
- Author
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Yan Zhang, Peng Liu, Wanzhuo Ma, Tianshu Wang, Bi Mingzhe, Qingsong Jia, Yuwei Su, Peng Zhang, and Jiang Huilin
- Subjects
Birefringence ,Materials science ,business.industry ,Materials Science (miscellaneous) ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Lyot filter ,Laser ,01 natural sciences ,Industrial and Manufacturing Engineering ,law.invention ,010309 optics ,Optics ,Mode-locking ,Fiber Bragg grating ,law ,Fiber laser ,0103 physical sciences ,Continuous wave ,Business and International Management ,0210 nano-technology ,Comb filter ,business - Abstract
We propose and experimentally demonstrate a widely tunable mode-locked thulium-doped fiber laser. The laser can operate at both continuous-wave and mode-locked states at different pump power levels. A classic nonlinear polarization rotation structure is employed to obtain the passive mode-locked laser. A birefringence Lyot filter as a fiber comb filter is used to expand the tuning range. Thanks to the filtering component, the tuning range of the continuous-wave laser can reach 127 nm (1823–1950 nm). The tuning ranges of the single-wavelength and dual-wavelength mode-locked lasers are 94 nm (1835–1929 nm) and 87 nm (1831–1918 nm), respectively, with a 3.085 MHz repetition rate and 75 ps pulse width.
- Published
- 2017
21. Various Square-wave Pulses Generation in a Passive Mode-locked Fiber Laser
- Author
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Jing Zhang, Qingsong Jia, Tianshu Wang, Wanzhuo Ma, Qingchao Su, and Huilin Jiang
- Subjects
Mode locked fiber laser ,Materials science ,Optics ,Mode-locking ,Feature (computer vision) ,business.industry ,Fiber laser ,Square wave ,Nanosecond ,business - Abstract
The square-wave pulses in passive mode-locked fiber laser present noise-like feature at both normal square-wave state and step-like square-wave state with nanosecond level. Both the two pulses can stably operate at single-pulse and dual-pulse state.
- Published
- 2017
22. Stable multi-wavelength thulium-doped fiber laser based on all-fiber Mach–Zehnder interferometer
- Author
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Qingsong Jia, Tianshu Wang, Wanzhuo Ma, Peng Zhang, and Chunming Wan
- Subjects
Materials science ,business.industry ,Polarization-maintaining optical fiber ,Laser ,Mach–Zehnder interferometer ,Graded-index fiber ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Interferometry ,Optics ,Polarization controller ,law ,Fiber laser ,Optoelectronics ,Dispersion-shifted fiber ,Electrical and Electronic Engineering ,business - Abstract
We propose and experimentally demonstrate a multi-wavelength thulium-doped fiber (TDF) laser based on all-fiber Mach-Zehnder interferometer (MZI) at 1.9 mm. Here a segment of 4 m single-mode TDF is pumped by 1568 nm fiber laser for 2 mm band optical gain. The MZI includes two cascaded 3 dB coupler. A segment of 3.5 m long un-pumped polarization-maintaining TDF and polarization controller (PC) are joined in the ring cavity to suppress the mode competition. Multi-wavelength lasers at 1.9 mm with wavelength number from one to four are obtained by adjusting the PC and the stability of output power of multi-wavelength fiber laser is analyzed.
- Published
- 2014
23. Temperature sensing characteristics based on multi-wavelength Brillouin fiber laser
- Author
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Qingsong, Jia, primary, Tianshu, Wang, additional, Zhen, Wang, additional, Bowen, Chen, additional, Baoxue, Bo, additional, and Huilin, Jiang, additional
- Published
- 2018
- Full Text
- View/download PDF
24. High sensitive temperature sensing system based on multi-wavelength fiber laser with dispersion shifted fiber
- Author
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Qingsong Jia, Bowen Chen, Tianshu Wang, Desheng Zhao, and Zhen Wang
- Subjects
Materials science ,business.industry ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Temperature measurement ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,010309 optics ,Wavelength ,Optics ,Fiber laser ,0103 physical sciences ,Dispersion-shifted fiber ,Light beam ,Fiber ,Electrical and Electronic Engineering ,Center frequency ,0210 nano-technology ,business ,Computer Science::Databases ,Microwave - Abstract
A temperature sensing system based on a multi-wavelength Brillouin fiber laser (MBFL) is proposed and demonstrated. Two beams of Stokes light are generated in a temperature sensitive fiber and a reference fiber, respectively. Stokes light from temperature sensitive fiber can generate frequency shift with temperature changing, and two beams can produce a microwave signal by beat frequency. Therefore, change of temperature can be accurately measured according to variation of the central frequency of the beat frequency microwave signals. A 3.2 km long dispersion shifted fiber (DSF) is used as temperature sensitive fiber pumped by a Brillouin pump with power of 1.5 W, then more than 20 Stokes light wavelengths can be observed. By using the 18th order Stokes light pair, temperature sensitivity can be 19.93 MHz∕°C. The uncertainty of the temperature measurement is ± 0.125°C.
- Published
- 2018
25. Dual-pulses and harmonic patterns of a square-wave soliton in passively mode-locked fiber laser
- Author
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Qingsong Jia, Tianshu Wang, Jing Zhang, Qingchao Su, Jiang Huilin, and Wanzhuo Ma
- Subjects
Physics ,Physics and Astronomy (miscellaneous) ,business.industry ,Pulse duration ,Soliton (optics) ,02 engineering and technology ,Square wave ,01 natural sciences ,Pulse (physics) ,Power (physics) ,010309 optics ,020210 optoelectronics & photonics ,Amplitude ,Optics ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Harmonic ,business ,Instrumentation - Abstract
We demonstrate a square-wave soliton pulse passively mode-locked fiber laser. The mode-locked pulses are achieved by using a nonlinear amplifying loop mirror. Single-pulse operation at a fundamental repetition rate of 3.2 MHz is obtained. The optical spectrum presents the soliton feature of several sidebands. The pulse duration expands with increasing pump power, but the amplitude hardly varies. Pulse breaking occurs and a stable dual-pulse is obtained with a fixed interval of 48 ns. Harmonic mode-locked states can be achieved when the total pump power is higher than 740 mW. The harmonic pulses can also operate in both single-pulse and dual-pulse states.
- Published
- 2018
26. Amplified characteristics and supercontinuum generation of square-wave pulse fiber laser
- Author
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Wanzhuo Ma, Tianshu Wang, Qingsong Jia, Zhen Wang, Furen Wang, Chengbo Wang, Yinhao Bai, and Qingchao Su
- Subjects
Materials science ,business.industry ,General Engineering ,Single-mode optical fiber ,Physics::Optics ,02 engineering and technology ,Laser ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Supercontinuum ,Pulse (physics) ,law.invention ,010309 optics ,020210 optoelectronics & photonics ,Optics ,Mode-locking ,law ,Fiber laser ,0103 physical sciences ,Dispersion (optics) ,0202 electrical engineering, electronic engineering, information engineering ,Fiber ,business - Abstract
We experimentally studied a passive mode-locked square-wave fiber laser with net-normal dispersion by using a nonlinear amplifying loop mirror. The output pulse width of the square-wave pulse (SWP) can be extended with the increasing of the pump power as well as single pulse energy. The SWP can be amplified without shape distortion when the mode-locked laser is injected into an erbium-ytterbium codoped fiber amplifier. Then, by inputting the amplified SWPs into a single mode fiber (SMF), a supercontinuum (SC) can be observed with the spectral range of about 1550 to 1850 nm. Broader and flatter SC with the 20-dB spectral range of about 1550 to 1950 nm can also be generated using a segment of dispersion-shifted fiber instead of SMF.
- Published
- 2018
27. 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
-
Qingsong, Jia, primary, Tianshu, Wang, additional, Wanzhuo, Ma, additional, Zhen, Wang, additional, Qingchao, Su, additional, Baoxue, Bo, additional, and Huilin, Jiang, additional
- Published
- 2017
- Full Text
- View/download PDF
28. Hybrid Transmission of Laser and Microwave Based on Dual-wavelength Brillouin Fiber Laser
- Author
-
Qingsong, Jia, primary, Tianshu, Wang, additional, Wanzhuo, Ma, additional, Huilin, Jiang, additional, and Baoxue, Bo, additional
- Published
- 2017
- Full Text
- View/download PDF
29. L-band double Brillouin frequency spaced tunable multiwavelength Brillouin fiber laser
- Author
-
Tianshu Wang, Keyan Dong, Peng Zhang, and Qingsong Jia
- Subjects
Brillouin zone ,Optical amplifier ,Materials science ,Optics ,Brillouin scattering ,business.industry ,Fiber laser ,Wavelength-division multiplexing ,Circulator ,Output coupler ,business ,Semiconductor laser theory - Abstract
A tunable multi-wavelength Brillouin fiber laser with double Brillouin frequency spacing based on a four-port circulator is experimentally demonstrated. The fiber laser configuration formed by four-port circulator isolates the odd-order Brillouin stokes signal to circulate within the cavity only. In addition, it also allows propagation of the incoming Brillouin pump and even-order Stokes signals from four-port circulator to output coupler .A L-band erbiumdoped fiber (EDF) with 1480nm pump is used to amplify Stokes signals and to get more output channels. At the Brillouin pump power of 8dBm and the 1480 nm pump power of 200mw, 5 output channels with double Brillouin frequency spacing and tuning range of 20 nm from 1568nm to 1588nm are achieved.
- Published
- 2014
30. Experimental research on thulium-doped fiber ASE characteristics pumped by 976nm LD
- Author
-
Qingsong Jia, Hongwei Sun, Wanzhuo Ma, Jian Han, Tianshu Wang, Peng Zhang, and Huilin Jiang
- Subjects
Amplified spontaneous emission ,Materials science ,business.industry ,Filling factor ,Physics::Optics ,Polarization-maintaining optical fiber ,Laser linewidth ,Optics ,Fiber laser ,Wavelength-division multiplexing ,Optoelectronics ,Dispersion-shifted fiber ,Laser power scaling ,business - Abstract
In this paper, a segment of thulium-doped fiber is pumped by a 976nm laser diode.Broadband gain at centerwavelength of 1953nm is achieved. The maximum amplified spontaneous emission bandwidth is 8nm. Simultaneously, self- oscillation of wavelength spacing 0.073nm is observed. The output power and self- oscillation modes increase with pump power increasing and wavelength spacing of self-oscillation is unchanged.The relation between fiber length and output power at pump power 400mW is analyzed. Higher output power can be abtained by selecting a appropriate fiber length when pump power is unchanged. Through the experiment, a weak absorption band of thulium-doped fiber near 976nm is verified. The structure can be used as narrow linewidth broadband source near 1950nm with the characteristic of low cost, simple structure and good stability.
- Published
- 2014
31. A dual-wavelength erbium-doped fiber laser based on fiber grating pair
- Author
-
Hongwei Sun, Tianshu Wang, Qingsong Jia, Huilin Jiang, and Peng Zhang
- Subjects
Materials science ,business.industry ,Physics::Optics ,Polarization-maintaining optical fiber ,Long-period fiber grating ,Graded-index fiber ,Optics ,Fiber Bragg grating ,Fiber optic sensor ,Fiber laser ,Optoelectronics ,Dispersion-shifted fiber ,business ,Photonic-crystal fiber - Abstract
A dual-wavelength linear cavity erbium-doped fiber (EDF) laser based on a fiber grating pair is demonstrated experimentally. A circulator, a 980nm/1550nm wavelength division multiplexing (WDM) coupler, a 1×2 coupler, a polarization controller, a 6m long erbium-doped fiber and a fiber grating pair for wavelength interval of 0.3nm are included in the structure. A circulator connected at two ports as reflecting mirror structure. A 980nm pump source pump an erbium-doped fiber with a length of 6m consist of an erbium doped fiber amplifier. Through adjusting the state of the polarization controller, the transmission characteristic of cavity is changed. In both polarization and wavelength, the feedback from the fiber grating pair results in the laser operating on two longitudinal modes that are separated. The birefringence induced by the fiber grating pair is beneficial to diversify the polarization states of different wavelength in the erbium-doped fiber. So it is enhanced the polarization hole burning effect. This polarization hole burning effect greatly reduced the wavelength competition. Then, it was possible to achieve stable dual-wavelength. It turns out the structure generated the stable dual-wavelength with the 0.3nm wavelength interval and the output power is 0.13dBm in the end. The whole system have a simple and compact structure, it can work stably and laid a foundation for microwave/millimeter wave generator. It has a good application performance in the future for scientific research and daily life.
- Published
- 2014
32. 40nm tunable multi-wavelength fiber laser
- Author
-
Huilin Jiang, Tianshu Wang, Qingsong Jia, Peng Zhang, and Keyan Dong
- Subjects
Optical fiber ,Materials science ,business.industry ,Polarization-maintaining optical fiber ,law.invention ,Double-clad fiber ,Optics ,Fiber Bragg grating ,law ,Fiber laser ,Optoelectronics ,Dispersion-shifted fiber ,Laser power scaling ,business ,Tunable laser - Abstract
A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier(EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.
- Published
- 2014
33. Triple Brillouin frequency spacing multiwavelength fiber laser with double Brillouin cavities and its application in microwave signal generation
- Author
-
Tianshu Wang, Wanzhuo Ma, Qingsong Jia, Zhen Wang, Qingchao Su, and Peng Zhang
- Subjects
Amplified spontaneous emission ,Materials science ,business.industry ,02 engineering and technology ,01 natural sciences ,Signal ,Atomic and Molecular Physics, and Optics ,010309 optics ,Brillouin zone ,Laser linewidth ,Wavelength ,020210 optoelectronics & photonics ,Optics ,Brillouin scattering ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,business ,Engineering (miscellaneous) ,Microwave - Abstract
We propose and experimentally investigate a multiwavelength Brillouin fiber laser (MBFL) with triple frequency spacing by employing a modular structure. In this scheme, we obtain nine channels optimized with frequency spacing of 0.259 nm. The single, double, and triple Brillouin frequency spacing for the MBFL can be easily realized by utilizing this modular structure. The impact of Brillouin pump (BP) power, BP wavelength, and erbium-ytterbium-doped fiber amplifier (EYDFA) output power on the performance of the MBFL is investigated, respectively. We also study the generation of beating frequency microwave signals based on single, double, and triple frequency spacing MBFL. 10.5 GHz, 21.48 GHz, and 31.77 GHz microwave signals with 3 dB linewidth of 16.4 MHz, 15.2 MHz, and 12.8 MHz are generated, respectively.
- Published
- 2017
34. Passively harmonic mode-locked pulses in thulium-doped fiber laser based on nonlinear polarization rotation
- Author
-
Peng Liu, Tianshu Wang, Wanzhuo Ma, Baoxue Bo, Yan Zhang, Qingsong Jia, and Peng Zhang
- Subjects
Materials science ,business.industry ,Doping ,General Engineering ,Single pulse ,Physics::Optics ,chemistry.chemical_element ,Nonlinear polarization ,02 engineering and technology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010309 optics ,020210 optoelectronics & photonics ,Thulium ,Optics ,chemistry ,Fiber laser ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Pulse wave ,business ,Dispersion compensation - Abstract
A simple approach to generate passively harmonic mode-locked pulse trains in thulium-doped fiber laser based on nonlinear polarization rotation is proposed and demonstrated. Three different ways of mode-locked techniques have been employed in our structure to generate passively high-order harmonic mode-locked pulse trains; 128th-order passively harmonic mode-locked pulse train is achieved in the experiment and the repetition rate is 406.8 MHz. With the increase of the pump power, multiwavelength output can be tuned. A segment of dispersion compensation fiber is used to compensate the dispersion in the cavity; thus, the single pulse width is compressed from 617 to 48 ps.
- Published
- 2016
35. Space laser communication system based on fiber laser phased array
- Author
-
Mingzhe, Bi, primary, Yuwei, Su, additional, Wanzhuo, Ma, additional, Xianzhu, Liu, additional, Mingru, Ci, additional, Qingsong, Jia, additional, Tianshu, Wang, additional, and Jingjiao, Liu, additional
- Published
- 2016
- Full Text
- View/download PDF
36. Stable multi-wavelength thulium-doped fiber laser based on all-fiber Mach–Zehnder interferometer
- Author
-
Peng Zhang, Peng Zhang, primary, Wanzhuo Ma, Wanzhuo Ma, additional, Tianshu Wang, Tianshu Wang, additional, Qingsong Jia, Qingsong Jia, additional, and Chunming Wan, Chunming Wan, additional
- Published
- 2014
- Full Text
- View/download PDF
37. An ultra-narrow linewidth multiwavelength fiber laser without linear gain
- Author
-
Xin Liu, Mei Kong, Qingsong Jia, Huilin Jiang, Peng Zhang, Tianshu Wang, and Shoufeng Tong
- Subjects
Laser linewidth ,Distributed feedback laser ,Optics ,Double-clad fiber ,Materials science ,business.industry ,Fiber optic sensor ,Brillouin scattering ,Fiber laser ,Optoelectronics ,Laser power scaling ,business ,Graded-index fiber - Abstract
An ultra-narrow linewidth multiwavelength Brillouin fiber laser is demonstrated. Erbium-doped fiber amplifier with linear gain is not used in the structure to avoid the signal broaden. Multiwavelength output with identical interval and ultra-narrow linewidth will be obtained through the experiment. Because the whole system works with a simple structure, it can work stably and has a good application performance in the future. A one-way feedback multiwavelength Brillouin fiber laser structure has been designed. A 2x2 3dB coupler, a 8 km-long single-mode fiber (SMF), a distributed feedback(DFB) semiconductor laser and two optical circulators are included in the structure. A segment of 8 km-long single-mode fiber (SMF) between the two ports of a 2x2 3 dB coupler is used as Brillouin gain loop. A distributed feedback semiconductor laser works as the Brillouin pump (BP). Laser output and feedback are realized by two optical circulators. We adopt the Brillouin pump power at 80 mW. Seven Stokes signals can be observed excluding BP. The Brillouin frequency shift is 0.088 nm compares with the wavelength of BP. We have measured multiwavelength Brillouin fiber laser spectrum ten times in 50 minutes. The experiment result shows that the multiwavelength output of Brillouin fiber laser is very stable. The 3 dB linewidth of the output laser is 5 kHz measured by the frequency spectrum analyzer.
- Published
- 2013
38. 60 nm tunable multi-wavelength fiber laser with Brillouin gain loop
- Author
-
Qingsong Jia, Tianshu Wang, Huilin Jiang, and Peng Zhang
- Subjects
Optical amplifier ,Distributed feedback laser ,Materials science ,business.industry ,Physics::Optics ,Round-trip gain ,law.invention ,Optics ,Brillouin scattering ,law ,Fiber laser ,Optical cavity ,Optoelectronics ,Laser power scaling ,business ,Tunable laser - Abstract
We demonstrate a multi-wavelength fiber laser with Brillouin cavity loop. Brillouin-Erbium fiber laser (BEFL) integrates Brillouin and Erbium gains in the resonate cavity to produce high power multi-wavelength fiber laser. The Brillouin gain loop connects with main ring cavity by port2 of the circulator1. A coil of SMF with a length of 10 km is employed by 3-dB fiber coupler as Brillouin gain medium, and pumped by Brillouin pump (BP), a tunable laser with a maximum output power of 15 dBm to generate Stokes light. The measured results were extracted from the laser system by using 90/10 coupler where 10% power is used for monitoring and measurement purpose while the 90% power is feedback into the laser cavity. A 1550 nm tunable laser diode (LD) provided the BP that can be tuned from 1470 nm to 1580 nm (110 nm tuning range). Two fiber circulators are used as the fiber reflection loops at both ends of the linear cavity. The effect of the erbium-doped fiber amplifier (EDFA) locating at different locations in the cavity BEFL on Stokes wave is experimentally studied. In the experiment, with EDFA in position A, the tunable range and the output power of the multi-wavelength laser were limited by gain saturation of the signals and the self-lasing cavity modes. The self-lasing cavity modes were suppressed without EDFA, but the tunable wavelength range was narrower because of the low gain. By using EDFA at the total reflective side of the linear cavity, more Stokes waves and wider tunable range was observed because the more powerful Stokes feedback light was amplified twice by the EDFA. The peak power of -1.8dBm and the tuning range of 60 nm were obtained. It has many important applications, such as dense wavelength division multiplexing (DWDM) systems, distributed fiber sensing, slow light, and microwave photonics, etc.
- Published
- 2013
39. A novel fiber laser based on Rayleigh scattering feedback with a half-opened cavity
- Author
-
Xianzhu Liu, Jiang Huilin, Shoufeng Tong, Wang Tong, Qingsong Jia, Mei Kong, and Peng Zhang
- Subjects
Materials science ,Optical fiber ,business.industry ,Physics::Optics ,Polarization-maintaining optical fiber ,Graded-index fiber ,law.invention ,Optics ,Fiber Bragg grating ,law ,Fiber laser ,Dispersion-shifted fiber ,business ,Plastic optical fiber ,Photonic-crystal fiber - Abstract
We demonstrate a distributed feedback (DFB) random fiber laser based on Rayleigh scattering. Amplified spontaneous emission is produced by using a segment of erbium doped fiber (EDF) pumped by 980 nm laser diode (LD). An 50km-long single-mode fiber (SMF) and a fiber bragg grate (FBG) are used as random resonate cavity and wavelength output at 1550 nm is observed which can be amplified through the erbium-doped fiber amplifier. Evaluations on the spectral evolution and power development are also performed from the results obtained.
- Published
- 2013
40. Passively Mode-Locked Fiber Lasers Based on Nonlinearity at 2-μm Band.
- Author
-
Tianshu Wang, Wanzhuo Ma, Qingsong Jia, Qingchao Su, Peng Liu, and Peng Zhang
- Abstract
2-μm fiber lasers are of wide potential applications in the fields of radar, sensing, and free-space communications. We introduced a simple approach to generate passively mode-locked pulse in thulium-doped fiber lasers based on nonlinear polarization rotation (NPR) in our previous work. The high repetition rate of 1.78 GHz is obtained by both NPR and semiconductor saturable absorption mirror. By using a polarization-maintaining fiber in the experiment, a birefringence Lyot filter as a fiber comb filter can be constructed, and then the tuning range of 94 nmcan be obtained for the mode-locked laser. In this paper, we also demonstrated our recent research work, a square-wave mode-locked fiber laser at 2-μmband based on nonlinear amplifying loop mirror.The squarewave noiselike pulse (NLP) at longer wavelength of 2-μmband can be observed.With the increase of the pump power, pulse width can be increased from 0.75 to 1.3 ns. The polarization vector characteristics of the square-wave NLP were analyzed experimentally. In addition, with the increase of the pump power, a kind of squarewave mode-locked pulse with low-intensity multipulse bunches can be observed, and these multipulse bunches can be operated at the multipulse mode-locked state. The side-mode suppression ratio decreased from 50 to 30 dB. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
41. Amplified characteristics and supercontinuum generation of square-wave pulse fiber laser.
- Author
-
Qingchao Su, Tianshu Wang, Wanzhuo Ma, Qingsong Jia, Yinhao Bai, Zhen Wang, Furen Wang, and Chengbo Wang
- Subjects
OPTICAL fibers ,FIBER optic cables ,NONLINEAR optics - Abstract
We experimentally studied a passive mode-locked square-wave fiber laser with net-normal dispersion by using a nonlinear amplifying loop mirror. The output pulse width of the square-wave pulse (SWP) can be extended with the increasing of the pump power as well as single pulse energy. The SWP can be amplified without shape distortion when the mode-locked laser is injected into an erbium-ytterbium codoped fiber amplifier. Then, by inputting the amplified SWPs into a single mode fiber (SMF), a supercontinuum (SC) can be observed with the spectral range of about 1550 to 1850 nm. Broader and flatter SC with the 20-dB spectral range of about 1550 to 1950 nm can also be generated using a segment of dispersion-shifted fiber instead of SMF. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
42. AN APPLICATION OF 24MODEL TO ANALYSE CAPSIZING OF THE EASTERN STAR FERRY.
- Author
-
Xiao Suo, Gui Fu, Chunxue Wang, and Qingsong Jia
- Subjects
FERRY accidents ,PASSENGER ships ,ROLL-on/roll-off ships ,RIVER boats ,TRANSPORTATION accidents - 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. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
43. Multiwavelength tunable ring fiber laser operating at 1.9 μm
- Author
-
Aihui, Gong, primary, Wanzhuo, Ma, additional, Tianshu, Wang, additional, Qingsong, Jia, additional, Peng, Zhang, additional, and Chunming, Wan, additional
- Published
- 2014
- Full Text
- View/download PDF
44. Passively harmonic mode-locked pulses in thulium-doped fiber laser based on nonlinear polarization rotation.
- Author
-
Qingsong Jia, Tianshu Wang, Wanzhuo Ma, Peng Liu, Peng Zhang, Baoxue Bo, and Yan Zhang
- Subjects
- *
THULIUM , *POLARIZATION (Electricity) , *FIBER lasers - Abstract
A simple approach to generate passively harmonic mode-locked pulse trains in thulium-doped fiber laser based on nonlinear polarization rotation is proposed and demonstrated. Three different ways of mode-locked techniques have been employed in our structure to generate passively high-order harmonic mode-locked pulse trains; 128th-order passively harmonic mode-locked pulse train is achieved in the experiment and the repetition rate is 406.8 MHz. With the increase of the pump power, multiwavelength output can be tuned. A segment of dispersion compensation fiber is used to compensate the dispersion in the cavity; thus, the single pulse width is compressed from 617 to 48 ps. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
45. All-fiber laser generating at 3.8 μm pumped by 1565 nm fiber laser and the second-order laser at 1.9 μm
- Author
-
Tianshu, Wang, primary, Yizhen, Wei, additional, Kai, Hu, additional, Peng, Zhang, additional, Qingsong, Jia, additional, and Huilin, Jiang, additional
- Published
- 2014
- Full Text
- View/download PDF
46. Frequency switched narrow linewidth microwave signal photonic generation based on a double-Brillouin-frequency spaced fiber laser
- Author
-
Keyan Dong, Huilin Jiang, Hongwei Sun, Qingsong Jia, Mei Kong, Xin Liu, Tianshu Wang, and Peng Zhang
- Subjects
Heterodyne ,Materials science ,business.industry ,Physics::Optics ,Output coupler ,Signal ,Atomic and Molecular Physics, and Optics ,law.invention ,Brillouin zone ,Laser linewidth ,Optics ,law ,Brillouin scattering ,Fiber laser ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Engineering (miscellaneous) ,Optical attenuator - Abstract
A simple photonic approach to generate microwave frequency switched microwave signal is proposed and experimentally demonstrated. In this scheme, a Brillouin fiber laser with double-Brillouin-frequency spacing is used. The Brillouin ring configuration suppresses incoming Brillouin pump and even-order Stokes signals in the cavity. In addition, it also allows propagation of the odd-order Brillouin Stokes signals from configuration to output coupler. A dual-wavelength optical signal is heterodyned at the high-speed photodetector to produce a microwave signal. Frequency switched microwave signals, at 10.75 and 21.39 GHz, respectively, can be obtained through adjusting the polarization controller (PC) and loss of the variable optical attenuator (VOA).
- Published
- 2014
47. Frequency switched narrow linewidth microwave signal photonic generation based on a double-Brillouin-frequency spaced fiber laser.
- Author
-
Peng Zhang, Tianshu Wang, Qingsong Jia, Hongwei Sun, Keyan Dong, Xin Liu, Mei Kong, and Huilin Jiang
- Published
- 2014
- Full Text
- View/download PDF
48. Multiwavelength tunable ring fiber laser operating at 1.9 μm.
- Author
-
Aihui, Gong, Wanzhuo, Ma, Tianshu, Wang, Qingsong, Jia, Peng, Zhang, and Chunming, Wan
- Subjects
FIBER lasers ,WAVELENGTHS ,THULIUM ,DOPED semiconductors ,SINGLE-mode optical fibers ,OPTICAL pumping ,OPTICAL polarization - Abstract
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 [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
49. Dual-pulses and harmonic patterns of a square-wave soliton in passively mode-locked fiber laser.
- Author
-
Wanzhuo Ma, Tianshu Wang, Qingchao Su, Jing Zhang, Qingsong Jia, and Huilin Jiang
- Published
- 2018
- Full Text
- View/download PDF
50. Tunable ultra-narrow linewidth microwave generation from a double-loop Brillouin fiber laser.
- Author
-
Peng Zhang, Tianshu Wang, Qingsong Jia, Wanzhuo Ma, Keyan Dong, Xiaotao Kang, Lizhong Zhang, Shoufeng Tong, and Huilin Jiang
- Abstract
A simple photonic approach to generate an ultra-narrow linewidth microwave signal is proposed and experimentally demonstrated. In this scheme, a multi-wavelength Brillouin fiber laser (BFL) with a double-loop and un-pumped polarization maintaining erbium doped fiber (PM-EDF) is used. The double-loop configuration includes a 50 m long single-mode fiber (SMF) and a 10 m long SMF as Brillouin gain. The threshold and linewidth of the microwave source can be improved by using a double loop, while a 4 m long un-pumped PM-EDF is used to suppress unwanted side-modes. A dual-wavelength optical signal is heterodyned at the high-speed photo detector to produce a microwave signal by adjusting the polarization controller and the wavelength of the Brillouin pump. As a result, a tunable microwave signal from 10.605 to 10.887 GHz can be obtained. The linewidth of the microwave signal is about 14.4 kHz, and the side-mode suppression ratio is about 30 dB. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
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