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Passively spatiotemporal gain-modulation-induced stable pulsing operation of a random fiber laser

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Photonics Research 2017年第6期5卷 117-122页

作者： jiangming xu JUN YE WEI LIU JIAN WU HANWEI ZHANG JINYONG LENG PU ZHOU College of Optoelectronic Science and Engineering National University of Defense Technology Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser

Unlike a traditional fiber laser with a defined resonant cavity, a random fiber laser(RFL), whose operation is based on distributed feedback and gain via Rayleigh scattering(RS) and stimulated Raman scattering in a long passive fiber, has fundamental scientific challenges in pulsing operation for its remarkable cavity-free feature. For the time being, stable pulsed RFL utilizing a passive method has not been reported. Here, we propose and experimentally realize the passive spatiotemporal gain-modulation-induced stable pulsing operation of counterpumped RFL. Thanks to the good temporal stability of an employed pumping amplified spontaneous emission source and the superiority of this pulse generation scheme, a stable and regular pulse train can be ***, the pump hysteresis and bistability phenomena with the generation of high-order Stokes light is presented, and the dynamics of pulsing operation is discussed after the theoretical investigation of the counterpumped RFL. This work extends our comprehension of temporal property of RFL and paves an effective novel avenue for the exploration of pulsed RFL with structural simplicity, low cost, and stable output.

关键词： RFL Passively spatiotemporal gain-modulation-induced stable pulsing operation of a random fiber laser

Multi-wavelength random fiber laser with a spectral-flexible characteristic

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Photonics Research 2023年第2期11卷 159-164页

作者： SICHENG LI jiangming xu JUNRUI LIANG JUN YE YANG ZHANG XIAOYA MA JINYONG LENG PU ZHOU College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

In past decades,multi-wavelength lasers have attracted much attention due to their wide applications in many *** this paper,we demonstrate a multi-wavelength random fiber laser with customizable spectra enabled by an acousto–optic tunable *** operating wavelength range can be tuned from 1114.5 to 1132.5 nm with a maximal output power of 5.55 W,and spectral channel tuning can also be realized with a maximal number of *** effect of gain competition and the interaction between Raman gain and insertion loss are also ***,the output spectra can be ordered by radiating appropriate radio frequency signals to the acousto–optic tunable *** work may provide a reference for agile shape spectrum generation and promote multi-wavelength random fiber laser practicability in sensing,telecommunications,and precise spectroscopy.

关键词： fiber laser tuning

Pump scheme optimization of an incoherently pumped high-power random fiber laser

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Photonics Research 2019年第9期7卷 977-983页

作者： JUN YE jiangming xu JIAXIN SONG ANG ZHANG HANWEI ZHANG HU XIAO JINYONG LENG PU ZHOU College of Advanced Interdisciplinary Studies National University of Defense Technology

Optical signal-to-noise ratio(OSNR) is one of the most significant parameters for the performance characterization of random fiber lasers(RFLs) and their application potentiality in sensing and telecommunication. An effective way to improve the OSNR of RFLs is pump scheme optimization, for example, employing a temporally stable source as the pump. In this paper, the output performance of an incoherently pumped RFL dependence on the pump bandwidth has been investigated both in experiment and theory. It is found that a high-OSNR RFL can be achieved with broadband amplified spontaneous emission(ASE) source pumping, and a relatively broad pump bandwidth can also help suppress the spectral broadening while maintaining an ultra-high spectral *** optimizing the pump bandwidth to ~10 nm, maximum OSNR of ~39 dB(corresponding to a spectral purity of ~99.96%) with more than 99 W output power can be obtained. Moreover, for the pump bandwidth of 0.6–40 nm, the spectral purity can reach as high as >99% with the pump power ranging from ~85 to ~117 *** addition, with the aid of theoretical simulation based on a modified power balance model, we find that the increment of pump bandwidth can decrease the effective Raman gain coefficient, further influencing the gain characteristics, nonlinear effects, and eventually the output performance. This work provides new insight into the influence of the pump characteristics on the output performance of incoherently pumped RFLs.

关键词： Raman Pump scheme optimization of an incoherently pumped high-power random fiber laser

Vortex random fiber laser with controllable orbital angular momentum mode

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Photonics Research 2021年第2期9卷 266-271页

作者： XIAOYA MA JUN YE YANG ZHANG jiangming xu JIAN WU TIANFU YAO JINYONG LENG PU ZHOU College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

In this paper, we propose and experimentally demonstrate a vortex random fiber laser(RFL) with a controllable orbital angular momentum(OAM) mode. The topological charge of the vortex RFL can range from-50 to 50 with nearly watt-level output power. A triangular toroidal interferometer is constructed to verify the spiral phase structure of the generated vortex random laser with a special coherence property. Vortex RFLs with fractional topological charge are also performed in this work. As the first demonstration of a vortex RFL with a controllable OAM mode(to the best of our knowledge), this work may not only offer a valuable reference on temporal modulation of a vortex beam and optical field control of an RFL but also provide a potential vortex laser source for applications in imaging, sensing, and communication.

关键词： fiber interferometer random

拌摩擦焊焊缝缺陷超声检测信号特征分析与神经网络模式识别

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核动力工程 2020年第1期41卷 163-166页

作者：徐蒋明柯黎明中国核动力研究设计院成都610213 南昌航空大学航空制造工程学院南昌330063

以搅拌摩擦焊(FSW)焊缝的包铝层伸入、未焊透、隧道孔缺陷为对象,将小波分析理论应用于缺陷超声检测信号特征提取问题的研究,使用小波包分解重构节点能量、小波包分解节点系数、缺陷信号的功率谱密度小波分解这三种方法对缺陷的超声检... 详细信息

以搅拌摩擦焊(FSW)焊缝的包铝层伸入、未焊透、隧道孔缺陷为对象,将小波分析理论应用于缺陷超声检测信号特征提取问题的研究,使用小波包分解重构节点能量、小波包分解节点系数、缺陷信号的功率谱密度小波分解这三种方法对缺陷的超声检测信号进行特征提取。利用类别可分离性判据和BP神经网络分别对提取的特征量进行评估和识别。结果表明,缺陷信号的功率谱密度小波分解这一特征提取方式具有最好的类别可分性,并且以该特征量为网络输入的BP神经网络具有85.71%缺陷识别率。

关键词：搅拌摩擦焊(FSW) 超声检测小波分析神经网络

Cladding-pumped Raman fiber laser with 0.78%quantum defect enabled by phosphorus-doped fiber

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High Power Laser Science and Engineering 2022年第2期10卷 1-6页

作者： Xiaoya Ma jiangming xu Jun Ye Yang Zhang Liangjin Huang Tianfu Yao Jinyong Leng Zhiyong Pan Pu Zhou College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073 China

The quantum defect(QD)is an important issue that demands prompt attention in high-power fiber lasers.A large QD may aggravate the thermal load in the laser,which would impact the frequency,amplitude noise and mode stability,and threaten the security of the high-power laser ***,we propose and demonstrate a cladding-pumped Raman fiber laser(RFL)with QD of less than 1%.Using the Raman gain of the boson peak in a phosphorus-doped fiber to enable the cladding pump,the QD is reduced to as low as 0.78%with a 23.7 W output *** our knowledge,this is the lowest QD ever reported in a cladding-pumped ***,the output power can be scaled to 47.7 W with a QD of 1.29%.This work not only offers a preliminary platform for the realization of high-power low-QD fiber lasers,but also proves the great potential of low-QD fiber lasers in power scaling.

关键词： cladding pumping lowquantum defect phosphorus-doped fiber Ramanfiber laser

kW-level,narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme

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High Power Laser Science and Engineering 2017年第4期5卷 43-47页

作者： Man Jiang Pengfei Ma Long Huang jiangming xu Pu Zhou Xijia Gu College of Optoelectronic Science and Engineering National University of Defense TechnologyChangsha 410073China Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser Changsha 410073China Department of Electrical and Computer Engineering Ryerson University350 Victoria St.TorontoOntario M5B 2K3Canada

In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode–multimode–single-mode structure seed laser, a linearly polarized Yb-doped fiber laser with narrow linewidth and high output power is *** laser, when used as a master oscillator, can be capable of suppressing the ASE in the process of power ***, only one-stage amplification structure is used to scale up the laser power, and linearly polarized output with a polarization extinction ration of 14 d B, a narrow linewidth of 0.3 nm and an output power of 1018 W are ***, due to the good beam quality of seed laser and the well-designed amplifier stage, the beam quality of the output laser is near-diffraction-limited with M_x^2 ~1.18 and M_y^2 ~ 1.24 at the maximum power, and without mode instability occurring.

关键词： fiber amplifier fiber Bragg grating linearly polarization narrow linewidth

Optical rogue wave in random fiber laser

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Photonics Research 2020年第1期8卷 1-7页

作者： jiangming xu JIAN WU JUN YE JIAXIN SONG BAICHENG YAO HANWEI ZHANG JINYONG LENG WEILI ZHANG PU ZHOU YUNJIANG RAO College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Fiber Optics Research Centre Key Laboratory of Optical Fiber Sensing&Communications(Ministry of Education)University of Electronic Science&Technology of ChinaChengdu 611731China

The famous demonstration of optical rogue waves(RWs),a powerful tool to reveal the fundamental physics in different laser scenarios,opened a flourishing time for temporal *** fiber laser(RFL)has likewise attracted wide attention due to its great potential in multidisciplinary demonstrations and promising ***,owing to the distinctive cavity-free structure,it is a scientific challenge to achieve temporal localized RWs in RFLs,whose feedback arises from multiple scattering in disordered ***,we report the exploration of RW in the highly skewed,transient intensity of an incoherently pumped RFL for the first time,to our knowledge,and unfold the involved kinetics *** corresponding frequency domain measurements demonstrate that the RW event arises from a crucial sustained stimulated Brillouin scattering process with intrinsic stochastic *** investigation highlights a novel path to fully understanding the complex physics,such as photon propagation and localization,in disordered media.

关键词： fiber scattering pumped

304L奥氏体不锈钢搅拌摩擦焊与TIG焊接头的微观组织与性能

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核动力工程 2016年第1期37卷 57-61页

作者：徐蒋明徐春容樊保全王世忠中国核动力研究设计院成都610213 中国核动力研究设计院反应堆燃料及材料重点实验室成都610213

采用搅拌摩擦焊和钨极惰性气体保护电弧焊(TIG)分别对3 mm厚304L奥氏体不锈钢进行焊接,对比分析2种焊接方法下接头的微观组织和抗拉强度。304L不锈钢的搅拌摩擦焊焊接接头由焊核区、热力影响区、热影响区及轴肩变形区组成;焊核区组织为... 详细信息

采用搅拌摩擦焊和钨极惰性气体保护电弧焊(TIG)分别对3 mm厚304L奥氏体不锈钢进行焊接,对比分析2种焊接方法下接头的微观组织和抗拉强度。304L不锈钢的搅拌摩擦焊焊接接头由焊核区、热力影响区、热影响区及轴肩变形区组成;焊核区组织为均匀细小的动态再结晶组织,热力影响区组织发生明显的塑性变形,而热影响区仅受到热的作用晶粒有所长大;TIG焊接头组织由呈胞状树枝奥氏体晶和呈蠕虫状或板条状铁素体组成。结果表明:2种焊接方法获得的接头强度相似,都略高于母材强度。

关键词： 304L奥氏体不锈钢搅拌摩擦焊 TIG焊微观组织性能