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Monolithic high-average-power linearly polarized nanosecond pulsed fiber laser with near-diffraction-limited beam quality

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High Power Laser Science and Engineering 2018年第3期6卷 28-35页

作者： Long Huang Pengfei Ma Daren Meng Lei Li Rumao Tao Rongtao Su Yanxing Ma pu zhou College of Optoelectronic Science and Engineering National University of Defense Technology Changsha 410073 China Hunan Provincial Collaborative Innovation Center of High Power Fiber Laser Changsha 410073 China

An all-fiberized high-average-power narrow linewidth ns pulsed laser with linear polarization is demonstrated. The laser system utilizes a typical master oscillator power amplifier(MOPA) configuration. The stimulated Brillouin scattering(SBS) is effectively suppressed due to the short fiber length and large mode area in the main amplifier, combined with the narrow pulse duration smaller than the phonon lifetime of SBS effect. A maximal output power of 466 W is obtained with a narrow linewidth of ～203.6 MHz, and the corresponding slope efficiency is ～80.3%. The pulse duration is condensed to be ～4 ns after the amplification, corresponding to the peak power of 8.8 kW and the pulse energy of 46.6 μJ. Neardiffraction-limited beam quality with an M2 factor of 1.32 is obtained at the output power of 442 W and the mode instability(MI) is observed at the maximal output power. To the best of our knowledge, this is the highest average output power of the all-fiberized narrow linewidth ns pulsed fiber laser with linear polarization and high beam quality, which is a promising source for the nonlinear frequency conversion, laser lidar, and so on.

关键词： all-fiber high power linear polarization mode instability narrow linewidth stimulated Brillouin scattering

Six kilowatt record all-fiberized and narrow-linewidth fiber amplifier with near-diffraction-limited beam quality

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High Power Laser Science and Engineering 2022年第4期10卷 1-6页

作者： Guangjian Wang Jiaxin Song Yisha Chen Shuai Ren Pengfei Ma Wei Liu Tianfu Yao pu zhou College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

In this work,an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is *** to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8%is achieved through the fiber amplifier based on a conventional step-index active *** the maximum output power,the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is M_(x)^(2)=1.43,M_(y)^(2)=*** have also measured and compared the output properties of the fiber amplifier employing different pumping ***,the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping ***,this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.

关键词： fiber laser high power narrow linewidth

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

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

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

Comprehensive investigation on producing high-power orbital angular momentum beams by coherent combining technology

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High Power Laser Science and Engineering 2019年第2期7卷 88-96页

作者： Dong Zhi Tianyue Hou Pengfei Ma Yanxing Ma pu zhou Rumao Tao Xiaolin Wang Lei Si College of Advanced Interdisciplinary Studies.National University cf Defense Technology Changsha 410073China Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000.China

High-power orbital angular momentum(OAM)beams have distinct advantages in improving capacity and data receiving for free-space optical communication systems at long *** the coherent combination of a beam array technique and helical phase approximation by a piston phase array,we have proposed a generating system for a novel high-power beam carrying OAM,which could overcome the power limitations of a common vortex phase modulator and a single *** characteristics of this generating method and the orthogonality of the generated OAM beams with different eigenstates have been theoretically analyzed and *** a high-power OAM beam produced by coherent beam combination(CBC)of a six-element hexagonal fiber amplifier array has been experimentally *** show that the CBC technique utilized to control the piston phase differences among the array beams has a high efficiency of 96.3%.On the premise of CBC,we have obtained novel vortex beams carrying OAM of±1 by applying an additional piston phase array modulation on the corresponding beam *** experimental results agree approximately with the theoretical *** work could be beneficial to areas that need high-power OAM beams,such as ultra-long distance free-space optical communications,biomedical treatments,and powerful trapping and manipulation under deep potential wells.

关键词： orbital angular momentum beams coherent beam combination

High-power fiber laser with real-time mode switchability

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Chinese Optics Letters 2022年第2期20卷 73-79页

作者： Hanshuo Wu Jiangtao Xu Liangjin Huang Xianglong Zeng pu zhou College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai UniversityShanghai 200444China

A hundred-watt-level spatial mode switchable all-fiber laser is demonstrated based on a master oscillator power amplifier *** performance of the amplifier with two seed lasers,i.e.,with the acoustically induced fiber grating (AIFG) mode converter inside and outside the seed laser cavity,is ***-time mode switching with millisecond scale switching time between the LP;and LP;modes while operating in full power (>100 W) is realized through an AIFG driven by radio frequency *** work could provide a good reference for realizing high-power agile mode switchable fiber lasers for practical applications.

关键词： acoustically induced fiber grating high power fiber amplifier mode switching

High-peak-power temporally shaped nanosecond fiber laser immune to SPM-induced spectral broadening

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High Power Laser Science and Engineering 2019年第2期7卷 51-58页

作者： Rongtao Su Pengfei Ma pu zhou Zilun Chen Xiaolin Wang Yanxing Ma Jian Wu Xiaojun Xu College of Advanced Irerdisciplinary Studies National University of Defense TechnologyChangsha410073China State Key Laboratory of pulsed Power Laser Technology.Changsha410073 China Hunan Provincial Key Laboratory of High Energy Laser Technology Changsha410073China

High-peak-power transform-limited narrow-linewidth nanosecond all-fiber lasers are desired in a range of ***,their linewidths will be broadened by self-phase modulation(SPM).We propose a novel concept that generates transform-limited laser pulses by temporally shaping the pulse *** impact of the pulse shape on SPM-induced spectral broadening was studied numerically and *** was found theoretically that the square-shape pulsed laser is immune to SPM-induced spectral *** on this principle,we built a high-peak-power,linearly polarized,square-shape nanosecond all-fiber laser in a master oscillator power amplifier(MOPA)*** Brillouin scattering(SBS)limited peak powers of 4.02 kW,5.06 kW,6.52 kW and 9.30 kW were obtained at pulse widths of 8 ns,7 ns,6 ns and 5 *** to the square-shape pulsed seed,the linewidths at maximum peak power remained at 129.5 MHz,137.6 MHz,156.2 MHz and 200.1 MHz,respectively,close to the transform-limited values of110.8 MHz,126.6 MHz,147.7 MHz and 177.3 MHz.

关键词： fiber laser nanosecond pulsed laser narrow linewidth self-phase modulation stimulated Brillouin scattering

High-power broadband supercontinuum generation through a simple narrow-bandwidth FBGs-based fiber laser cavity

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Chinese Optics Letters 2022年第1期20卷 85-88页

作者： Song Zhang Man Jiang Can Li Rongtao Su pu zhou Zongfu Jiang College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

The generation of supercontinuum(SC) often requires ultrashort pulsed lasers with high peak power and gain media with large nonlinear coefficients,such as a long piece of fiber or photonic crystal *** this Letter,we propose and demonstrate that high-power SC can be generated through a simple narrow-bandwidth fiber Bragg gratings(FBGs)-based laser cavity without any modulation,based on the mechanism of intense nonlinear effects induced by the inherent self-pulsation generated inside the *** the experiment,an ~80 W SC laser with the spectrum range from <600 nm to 1600 nm was *** the best of our knowledge,this is the first report about SC generation through a simple fiber laser *** work enriches the research content of SC and provides a cost-effective method for high-power SC lasers.

关键词： supercontinuum fiber laser narrow-linewidth laser