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High-power mode-programmable orbital angular momentum beam emitter with an internally sensed optical phased array

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Chinese Optics Letters 2024年第2期22卷 120-127页

作者：龙金虎邓宇高志强常洪祥常琦马阎星吴坚粟荣涛马鹏飞周朴 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Nanhu Laser Laboratory National University of Defense TechnologyChangsha 410073China Hunan Provincial Key Laboratory of High Energy Laser Technology National University of Defense TechnologyChangsha 410073China

The high-power mode-programmable orbital angular momentum(OAM)beam has attracted significant attention in a wide range of applications,such as long-distance optical communication,nonlinear frequency conversion,and beam shaping.Coherent beam combining(CBC)of an optical phased array(OPA)can offer a promising solution for both generating the high-power OAM beam and rapidly switching the OAM modes.However,achieving real-time phase noise locking and formation of desired phase structures in a high-power CBC system faces significant challenges.Here,an internal phase-sensing technique was utilized to generate the high-power OAM beam,which effectively mitigated thermal effects and eliminated the need for large optical devices.An OPA with six elements was employed for experimental demonstration.The first effective generation of over 1.5 kW mode-programmable OAM beam in a continuous-wave domain was presented.Moreover,the results demonstrated that the generated OAM beam could be modulated with multiple dimensions.The topological charge can be switched in real time from-1 to-2.Notably,this OAM beam emitter could function as an OAM beam copier by easily transforming a single OAM beam into an OAM beam array.More importantly,a comprehensive analysis was conducted on power scaling,mode switching speed,and expansion of OAM modes.Additionally,the system’s compact design enabled it to function as a packageable OAM beam emitter.Owing to the advantages of having high power and programmable modes with multiple dimension modulation in phase structures and intensity distribution,this work can pave the way for producing high-power structured light beams and advancing their applications.

关键词： orbital angular momentum optical vortex optical phased array coherent beam combining

光纤激光相干合成的研究历程与发展趋势:基于文献引用的视角(特邀)

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中国激光 2024年第1期51卷 432-456页

作者：周朴常洪祥粟荣涛王小林马阎星国防科技大学前沿交叉学科学院湖南长沙410073

从文献引用的视角全面回顾总结了光纤激光相干合成二十余年的研究历程。按照学术发展初期、学术高速发展期、学术发展平缓期和技术发展关键期等4个阶段,分别介绍了光纤激光相干合成的代表性成果,分析并总结了学术水平和影响力较为突出... 详细信息

从文献引用的视角全面回顾总结了光纤激光相干合成二十余年的研究历程。按照学术发展初期、学术高速发展期、学术发展平缓期和技术发展关键期等4个阶段,分别介绍了光纤激光相干合成的代表性成果,分析并总结了学术水平和影响力较为突出的文献,梳理了光纤激光相干合成从概念提出到实际应用的演进脉络,研判了未来发展趋势。

关键词：激光光学相干合成光纤激光研究历程

First experimental demonstration of coherent beam combining of more than 100 beams

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Photonics Research 2020年第12期8卷 1943-1948页

作者： HONGXIANG CHANG QI CHANG JIACHAO XI TIANYUE HOU RONGTAO SU PENGFEI ma JIAN WUCAN LI maN JIANG yanxing ma PU ZHOU College of Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China

Coherent beam combining of 107 beams has been demonstrated for the first time to the best of our knowledge.When the system was in closed loop,the pattern in far-field was stable and the fringe contrast was>96%.The impact of the dynamic tilt error,the piston error,and power inconsistency was theoretically analyzed.Meanwhile,the distribution law of dynamic tilt error was estimated and the correlation of the tilt dithering of different axis was analyzed statistically.The ratio of power in the central lobe was^22.5%.The phase residue error in the closed loop was~λ∕22,which was evaluated by the root-mean-square error of the signal generated from the photoelectric detector.

关键词： error beam coherent

Nonlinear photoresponse of metallic graphene-like VSe2 ultrathin nanosheets for pulse laser generation

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Science China(Information Sciences) 2019年第12期62卷 141-148页

作者： Tao WANG Xinyao SHI Jin WANG Yijun XU Jie CHEN Zhuo DONG man JIANG Pengfei ma Rongtao SU yanxing ma Jian WU Kai ZHANG Pu ZHOU College of Advanced Interdisciplinary Studies National University of Defense Technology i-Lab Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Vacuum Interconnected Nanotech Workstation Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of Sciences

Vanadium diselenide(VSe2), a typical metallic behaviour material among transition metal dichalcogenides(TMDCs) family, exhibits excellent photoelectric characteristics with a zero band gap, missing applicaiotn in pulse generation. In this work, a high-quality VSe2 saturable absorber(SA) was synthesized through a liquid-phase exfoliation method. The saturable absorption of obtained VSe2-SA was characterized systematically. The measured modulation depth was 9.9%, and the saturated intensity was 533.8 μJ/cm2. By incorporating this optical modulator into a ytterbium-doped fiber laser cavity, a stable passively Q-switched laser could be achieved. The pulse had the central wavelength of 1064.03 nm. As the pump power was increased, the repetition rate increased from 24.3 k Hz to 35.6 k Hz, and the pulse duration decreased from7.21 μs to 5.27 μs. The output power had the maximum value of 28.55 m W. These results indicated that VSe2 is an effective candidate to generate pulse laser due to its excellent nonlinear optical properties and universal photoelectric response, which may advance the applications of VSe2-based nonlinear optics and photoelectric devices.

关键词： transition metal dichalcogenides VSe2 saturable absorber pulse laser fiber laser

Coumarin derivative dye sensitized NaYGdF4:Yb,Er nanoparticles with enhanced NIR Ⅱ luminescence for bio-vascular imaging

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Journal of Rare Earths 2023年第12期41卷 1843-1849,I0001页

作者： Yaqun ma Zhan Wang yanxing Wang Zhenghao Liu Yukun Wang Ruichan Lv Xi'an Key Laboratory of Intelligent Sensing and Regulation of Trans-Scale Life Information Engineering Research Center of Molecular and Neuro ImagingMinistry of EducationSchool of Life Science and TechnologyXidian UniversityXi'an710071China

Lanthanide-doped biocompatible nanoparticles have promising applications in near-infrared second region imaging due to their high chemical stability,enhanced photostability and sharp emission bandwidth.However,the weak light absorption capacity limits the application of rare-earth nanoparticles(RENPs) for bioimaging.We prepared a coumarin-derived dye sensitized NaYGdF4:Yb,Er nanoparticle probe,in which the organic dye enhances photon absorption through the sensitization process,improving the luminescence efficiency of the rare earth particles near 1000 and 1500 nm.In addition,good water solubility and stability of the probe are imparted by coating the particles with amphiphilic polymers distearoyl phosphatidylethanolamine-polyethylene glycol(DSPE-PEG) and polyacrylic acid.This composite probe with good biocompatibility and NIR Ⅱ luminescence properties can be used for vascular imaging,providing a tool for the detection of hematologic-related diseases.

关键词： Rare earth doped nanoparticles Dye sensitization NIR imaging Angiography

LDformer:a parallel neural network model for long-term power forecasting

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信息与电子工程前沿:英文版 2023年第9期24卷 1287-1301页

作者： Ran TIAN Xinmei LI Zhongyu ma yanxing LIU Jingxia WANG Chu WANG College of Computer Science&Engineering Northwest Normal UniversityLanzhou 730070China

Accurate long-term power forecasting is important in the decision-making operation of the power grid and power consumption management of customers to ensure the power system’s reliable power supply and the grid economy’s reliable operation.However,most time-series forecasting models do not perform well in dealing with long-time-series prediction tasks with a large amount of data.To address this challenge,we propose a parallel time-series prediction model called LDformer.First,we combine Informer with long short-term memory(LSTM)to obtain deep representation abilities in the time series.Then,we propose a parallel encoder module to improve the robustness of the model and combine convolutional layers with an attention mechanism to avoid value redundancy in the attention mechanism.Finally,we propose a probabilistic sparse(ProbSparse)self-attention mechanism combined with UniDrop to reduce the computational overhead and mitigate the risk of losing some key connections in the sequence.Experimental results on five datasets show that LDformer outperforms the state-of-the-art methods for most of the cases when handling the different long-time-series prediction tasks.

关键词： Long-term power forecasting Long short-term memory(LSTM) UniDrop Self-attention mechanism

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 applications.However,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 seed.The impact of the pulse shape on SPM-induced spectral broadening was studied numerically and experimentally.It was found theoretically that the square-shape pulsed laser is immune to SPM-induced spectral broadening.Based on this principle,we built a high-peak-power,linearly polarized,square-shape nanosecond all-fiber laser in a master oscillator power amplifier(MOPA)configuration.Stimulated 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 ns.Thanks 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

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：偏振脉冲激光器激光系统技术创新激光技术

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 distances.Utilizing 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 beam.The characteristics of this generating method and the orthogonality of the generated OAM beams with different eigenstates have been theoretically analyzed and verified.Also a high-power OAM beam produced by coherent beam combination(CBC)of a six-element hexagonal fiber amplifier array has been experimentally implemented.Results 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 array.The experimental results agree approximately with the theoretical analysis.This 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