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An All-Fiberized Chirped Pulse Amplification System Based on Chirped Fiber Bragg Grating Stretcher and Compressor

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Chinese Physics Letters 2022年第2期39卷 36-42页

作者： Ming-Xiao Wang Ping-Xue Li Yang-Tao Xu Yun-Chen Zhu Shun Li chuan-fei yao Institute of Ultrashort Pulsed Laser and Application Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China

We report an all-fiberized chirped pulse amplification system without any bulk *** stretcher and compressor are chirped fiber Bragg gratings inscribed in a 6/125μm single-mode fiber and a 30/250μm largemode-area *** fabrication system of chirped fiber Bragg gratings was designed and built by *** width of the linear exposure spot was controlled according to the different fiber sizes to improve the fabrication quality,and the parameters of chirped fiber Bragg gratings were fine-tuned during the fabrication to achieve the overall system’s spectral *** fiber circulators with the same fiber sizes as the chirped fiber Bragg gratings were employed to auxiliarily achieve the pulse stretching and *** dispersion accumulations provided by the stretcher and compressor are 129.8 ps and 90.8 *** power amplifiers were composed of the two-stage 10/130μm fiber pre-amplifier and the 30/250μm fiber main *** proposed chirped pulse amplification system with no spatial light is the true sense of an all-fiberized chirped pulse amplification structure and shows the main trend in development of ultrashort pulse fiber lasers.

关键词： fiber amplifier compressor

Influence of optical nonlinearity on combining efficiency in ultrashort pulse fiber laser coherent combining system

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Chinese Physics B 2022年第6期31卷 342-348页

作者： Yun-Chen Zhu Ping-Xue Li chuan-fei yao Chun-Yong Li Wen-Hao Xiong Shun Li Institute of Ultrashort Pulsed Laser and Application Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Department of Physics Durham UniversitySouth RoadDurham DH13LEUK

The influence of optical nonlinearity on combining efficiency in ultrashort pulse fiber laser coherent combining system is investigated theoretically and *** the theoretical work,a new theoretical algorithm is presented for the coherent combining efficiency,which can be used to quantify the spectral coherence decay induced by optical nonlinearity imbalance between the *** spectral information of the sub-beam is obtained by numerically solving the nonlinear Schrödinger equation(NLSE)in this algorithm to ensure an accurate *** the experimental work,the coherent combining of two all-fiber picosecond lasers is achieved,and the influence of imbalanced optical nonlinearity on the combining efficiency is studied,which agrees with the theoretical *** paper reveals the physical mechanism for the influence of optical nonlinearity on the combining efficiency,which is valuable for the coherent combining of ultrashort pulse fiber laser beams.

关键词： coherent beam combination spectral coherence optical nonlinearity

The 266-nm ultraviolet-beam generation of all-fiberized super-large-mode-area narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

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Chinese Physics B 2022年第3期31卷 292-298页

作者： Shun Li Ping-Xue Li Min Yang Ke-Xin Yu Yun-Chen Zhu Xue-Yan Dong chuan-fei yao Institute of Ultrashort Pulsed Laser and Application Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China

We report on a compact, stable, all-fiberized narrow-linewidth(0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fiberized nanosecond amplifier architecture, which consists of Yb-doped fiber preamplifiers and a super-large-mode-area Yb-doped fiber power amplifier. The fiber amplifier with a core of 50 μm is used to raise the threshold of the stimulated Brillouin scattering(SBS) effect and to obtain high output power and single pulse energy. Using lithium triborate(LBO) crystal and betabarium borate(BBO) crystal for realizing the second-harmonic generation(SHG) and fourth-harmonic generation(FHG),we achieve 17 μJ(1.73 W) and 0.66 μJ(66 mW), respectively, at wavelengths of 532 nm and 266 nm and a repetition rate of 100 kHz with pulse width of 4 ns. This source has great potential applications in fluorescence research and solar-blind ultraviolet optical communication.

关键词： nanosecond all-fiber amplifier narrow-linewidth ultraviolet beam generation tunable pulse width and repetition rate

All-fiberized very-large-mode-area Yb-doped fiber based high-peak-power narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

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Chinese Physics B 2020年第11期29卷 343-349页

作者： Min Yang Ping-Xue Li Dong-Sheng Wang Ke-Xin Yu Xue-Yan Dong Ting-Ting Wang chuan-fei yao Wei-Xin Yang Institute of Laser Engineering Beijing University of TechnologyBeijing 100124China

We demonstrate an all-fiberized narrow-linewidth nanosecond amplifier with high peak power,tunable pulse width,and repetition rate.A fiber-coupled narrow-linewidth laser diode operating at 1064.1 nm is employed as the seed source,which is gain-switched to generate nanosecond pulses with tunable pulse widths of 1-200 ns and tunable repetition rates of10 Hz-100 *** utilizing a very-large-mode-area Yb-doped fiber with a core diameter of 50 μm in the power amplifier,thresholds of the stimulated Brillouin scattering at different pulse widths and repetition rates are *** maximum average power reaches 30.8 W at the pulse width of 4 ns and a repetition rate of 100 kHz,corresponding to an optical-tooptical conversion efficiency of ~55.2%.Pulse energy and peak power are calculated to be 0.2 mJ and 50 kW,respectively,which are limited by stimulated Brillouin *** 3-dB spectral linewidth remains around 0.05 nm during the power scaling *** stimulated Brillouin scattering limited output powers at different pulse widths and repetition rates are *** power of 47.5 kW(0.19 mJ) is obtained for the 4 ns pulses at a repetition rate of 50 kHz,which is nearly the same as that of 4 ns pulses at 100 *** the pulse width of the seed source is increased to 8 ns,peak powers/pulse energies are decreased to 19.6 kW/0.11 mJ and 13.3 kW/0.08 mJ at repetition rates of 50 kHz and 100 kHz,respectively.

关键词： nanosecond all-fiber amplifier very-large mode area tunable pulse width and repetition rate

Intelligent responsive self-assembled micro-nanocapsules: Used to delay gel gelation time

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Petroleum Science 2024年第4期21卷 2433-2443页

作者： chuan-Hong Kang Ji-Xiang Guo Dong-Tao fei Wyclif Kiyingi Unconventional Petroleum Research Institute China University of Petroleum

In the application of polymer gels to profile control and water shutoff,the gelation time will directly determine whether the gel can "go further" in the formation,but the most of the methods for delaying gel gelation time are complicated or have low *** is an urgent need for an effective method for delaying gel gelation time with intelligent *** by the slow-release effect of drug capsules,this paper uses the self-assembly effect of gas-phase hydrophobic SiO2in aqueous solution as a capsule to prepare an intelligent responsive self-assembled *** capsule slowly releases the cross-linking agent under the stimulation of external conditions such as temperature and pH value,thus delaying gel gelation *** the pH value is 2 and the concentration of gas-phase hydrophobic SiO2particles is 10%,the gelation time of the capsule gel system at 30,60,90,and 120℃ is12.5,13.2,15.2,and 21.1 times longer than that of the gel system without containing capsule,*** with other methods,the yield stress of the gel without containing capsules was 78 Pa,and the yield stress after the addition of capsules was 322 *** intelligent responsive self-assembled micronanocapsules prepared by gas-phase hydrophobic silica nanoparticles can not only delay the gel gelation time,but also increase the gel *** slow release of cross-linking agent from capsule provides an effective method for prolongating the gelation time of polymer gels.

关键词： Profile control and water shutoff Polymer gel Delayed gelation time Intelligent response Self-assembled Micro-nanocapsules

Light sheet fluorescence microscopy: Advancing biological discovery with more dimensions, higher speed, and lower phototoxicity

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The Innovation 2024年第5期5卷 29-30页

作者： yao Zhou Shiqi Mao Peng fei School of Optical and Electronic Information-Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Advanced Biomedical Imaging Facility Huazhong University of Science and TechnologyWuhan 430074China

TO SEE THE WORLD IN A GRAIN OF *** microscopy has proved to be essential for seeing life in a grain of a *** epifluorescence microscopes,such as wide-field microscopes and laser scanning confocal microscopes,have been widely used for biology research over the past few *** goal of fluorescence microscopy is to observe the structure and function of cellular events across time and threedimensional(3D)space with spatiotemporal resolution as high as ***,conventional epifluorescence microscopes illuminate the entire 3D volume of the sample while detecting signals only from the 2D focal plane,thereby leading to low photon utilization and high phototoxicity issues that notably prevent high-resolution imaging of live biological specimens(Figure 1A).It becomes increasingly noteworthy that the massively emerging biomedical applications are posing significant challenges to current fluorescence microscopy techniques.

关键词： fluorescence dimensions Figure

Impacts of proppant distribution on development of tight oil reservoirs with threshold pressure gradient

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Petroleum Science 2024年第1期21卷 445-457页

作者： Ming Yue Wei-yao Zhu fei-fei Gou Tian-Ru Song Yu-Chun You Qi-Tao Zhang State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing102206China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China

Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well *** at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the *** with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture *** integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,*** results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the *** we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 ***,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil *** we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of *** general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.

关键词： Proppant distribution Tight oil reservoir Multi-stage fractured horizontal well Threshold pressure gradient Moving boundary

Three-Rigid-Body-Particle Modeling and Optimization of Trajectory and Posture for Alpine Skiing

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Journal of Systems Science & Complexity 2024年第2期37卷 581-608页

作者： ZHANG Yijia fei Qing yao Xiaolan SUN Jian ZHANG Yanjun CHEN Zhen School of Automation Beijing Institute of TechnologyBeijing 100081China

This paper presents a new study on modeling and optimization of trajectory and posture for the super-giant(SG)slalom of alpine *** is the first time that a Three-Rigid-Body-Particle model based on rigorous derivations and stability analysis is established to represent skiers trajectory and posture characteristics,as it is more accurate than the single-rigid-body model which is commonly used in existing *** addition,the Radau pseudospectral method is applied to solve the trajectory and posture optimization problem in order to obtain better skiing trajectory,skiing posture,and some key kinematic parameters of ***,this paper analyzes the effects of different body types,minimum turning radii,and flexor and extensor strength of knees and hip joint on skiing ***,based on the findings of the study,some advice about how to improve the performance of the SG slalom in view of science and technology is given to skiers and coaches for reference.

关键词： Alpine skiing modeling posture optimization Three-Rigid-Body-Particle model trajectory optimization

Energy-efficient computation offloading assisted by RIS-based UAV

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The Journal of China Universities of Posts and Telecommunications 2024年第1期31卷 37-48页

作者： Li Linpei Zhao chuan Su Yu Huo Jiahao Huang yao Li Haojin School of Intelligence Science and Technology University of Science and Technology BeijingBeijing 100083China Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China Shunde Innovation School University of Science and Technology BeijingFoshan 528399China School of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083China Research Department of 5G and Drone China Mobile(Chengdu)Institute of Research and DevelopmentChengdu 610200China College of Communication Engineering Chengdu University of Information TechnologyChengdu 610225China Research and Development Center Sony(China)LimitedBeijing 100027China

The new applications surge with the rapid evolution of the mobile *** explosive growth of the data traffic aroused by the new applications has posed great computing pressure on the local *** is essential to innovate the computation offloading methods to alleviate the local computing burden and improve the offloading *** edge computing(MEC)assisted by reflecting intelligent surfaces(RIS)-based unmanned aerial vehicle(UAV)is a promising method to assist the users in executing the computation tasks in proximity at low *** this paper,we propose an energy-efficient MEC system assisted by RIS-based UAV,where the UAV with RIS mounted relays the computation tasks to the MEC *** energy efficiency maximization problem is formulated by jointly optimizing the UAV's trajectory,the transmission power of all users,and the phase shifts of the reflecting elements placed on the *** that the optimization problem is non-convex,we propose a deep deterministic policy gradient(DDPG)-based *** combining the DDPG algorithm with the energy efficiency maximization problem,the optimization problem can be ***,the numerical results are illustrated to show the performance of the system and the superiority compared with the benchmark schemes.

关键词： mobile edge computing unmanned aerial vehicle reflecting intelligent surface