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Customized modulation on plasma uniformity by non-uniform magnetic field in capacitively coupled plasma

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plasma Science and Technology 2024年第6期26卷 79-87页

作者：王森张权治马方方 Maksudbek YUSUPOV 王友年 School of physics Dalian University of TechnologyDalian 116024People’s Republic of China Laboratory of Thermal physics of Multiphase Systems Arifov Institute of Ion-Plasma and Laser TechnologiesAcademy of Sciences of UzbekistanTashkent 100125Uzbekistan Department of Power Supply and Renewable Energy Sources National Research University TIIAMETashkent 100000Uzbekistan

A two-dimensional fluid model based on COMSOL Multiphysics is developed to investigate the modulation of static magnetic field on plasma homogeneity in a capacitively coupled plasma(CCP)chamber. To generate a static magnetic field, direct current is applied to a circular coil located at the top of the chamber. By adjusting the magnetic field's configuration, which is done by altering the coil current and position, both the plasma uniformity and density can be significantly modulated. In the absence of the magnetic field, the plasma density exhibits an inhomogeneous distribution characterized by higher values at the plasma edge and lower values at the center. The introduction of a magnetic field generated by coils results in a significant increase in electron density near the coils. Furthermore, an increase in the sets of coils improves the uniformity of the plasma. By flexibly adjusting the positions of the coils and the applied current,a substantial enhancement in overall uniformity can be achieved. These findings demonstrate the feasibility of using this method for achieving uniform plasma densities in industrial applications.

关键词： COMSOL capacitively coupled plasma plasma uniformity magnetic field

A comprehensive diagnostic system of ultra-thin liquid sheet targets

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High Power laser Science and Engineering 2024年第3期 46-55页

作者： Ziyang Peng Zhengxuan Cao Xuan Liu Yinren Shou Jiarui Zhao Shiyou Chen Ying Gao Pengjie Wang Zhusong Mei Zhuo Pan Defeng Kong Shirui Xu Zhipeng Liu Yulan Liang Tianqi Xu Tan Song Xun Chen Qingfan Wu Yujia Zhang Zihao Zhang Xueqin Yan Wenjun Ma State Key Laboratory of Nuclear physics and Technology School of Physics Peking University National Key Laboratory of Shock Wave and Detonation physics Institute of Fluid Physics China Academy of Engineering Physics Center for Relativistic laser Science Institute for Basic Science Gwangju Republic of Korea institute of Radiation physics Helmholtz-Zentrum Dresden Rossendorf Dresden Germany Beijing laser Acceleration Innovation Center institute of Guangdong laser plasma Technology

To meet the demands of laser-ion acceleration at a high repetition rate, we have developed a comprehensive diagnostic system for real-time and in situ monitoring of liquid sheet targets (LSTs). The spatially resolved rapid characterizations of an LST’s thickness, flatness, tilt angle and position are fulfilled by different subsystems with high accuracy. With the help of the diagnostic system, we reveal the dependence of thickness distribution on collision parameters and report the238-nm liquid sheet generated by the collision of two liquid jets. Control methods for the flatness and tilt angle of LSTs have also been provided, which are essential for applications of laser-driven ion acceleration and others.

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Spectral characteristics of laser-plasma instabilities with a broadband laser

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Chinese physics B 2024年第8期33卷 362-368页

作者：许国潇康宁雷安乐刘会亚赵耀周申蕾安红海熊俊王瑞荣谢志勇周熙晨方智恒王伟 Key Laboratory of High Power laser and physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Shanghai institute of laser plasma China Academy of Engineering PhysicsShanghai 201800China School of Science Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China University of Chinese Academy of Sciences Beijing 100049China

Recent experimental progresses regarding broadband laser-plasma instabilities(LPIs)show that a 0.6%laser bandwidth can reduce backscatters of the stimulated Brillouin scattering(SBS)and the stimulated Raman scattering(SRS)at normal incidence[***.132035102(2024)].In this paper,we present a further discussion of the spectral distributions of the scatters developed by broadband LPIs,in addition to a brief validation of the effectiveness of bandwidth on LPIs mitigation at oblique *** backscatter has a small redshift in the broadband case contrary to the blueshift with narrowband laser,which may be explained by the self-cross beam energy transfer between the various frequency components within the *** backscatter spectrum presents a peak at a longer wavelength in the broadband case compared to the short one in the narrowband case,which is possibly attributed to the mitigation effect of bandwidth on filaments at underdense *** three-halves harmonic emission(3ω/2)has a one-peak spectral distribution under the broadband condition,which is different from the two-peak distribution under the narrowband condition,and may be related to the spectral mixing of different frequency components within the bandwidth if the main sources of the two are both two-plasmon decays.

关键词： laser-plasma instability laser bandwidth light spectrum

Local environment regulation of transition metal dichalcogenide-based single-atom catalysts

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Rare Metals 2024年第9期43卷 4019-4037页

作者： Ming-Hui Li Jing Li Xiao-Yu Zheng Yao Zhou Advanced Research institute of Multidisciplinary Science andSchool of Chemistry and Chemical Engineering Beijing Institute of Technology laser micro/Nano Fabrication Laboratory School of Mechanical Engineering Beijing Institute of Technology

Single-atom catalysts have risen significant attention in the realm of green electrocatalytic energy conversion to address energy and environmental sustainability challenges. Transition metal dichalcogenide（TMD）-based single-atom catalysts are considered highly effective in electrocatalysis due to the TMDs' notable specific surface area, tunable elemental species and efficient utilization of single atoms. In order to enhance electrocatalytic performance, it is imperative to elaborately engineer the local environment surrounding the active sites of single atoms within TMDs. In this review, we initially explore the effects of synthesis methods on single-atom active sites and the influence of loading of single atoms on catalytic performance for TMDs. The modulation strategies of the local environment surrounding single-atom sites in TMDs are elaborated, including substitution engineering,surface adsorption, vacancies, spatial confinement and dual-atom site strategies. For each modulation strategy, the effects of diverse local environments on various electrocatalytic applications are presented, such as the oxygen evolution reaction, oxygen reduction reaction, nitrogen reduction reaction, CO2reduction reaction and CO oxidation. Ultimately, this study presents a comprehensive overview of the challenges encountered and the potential directions for the advancement of single-atom catalysts based on TMDs in the realm of electrocatalysis.

关键词： Electrocatalysis

Linear mathematical model for the unique solution of 3D ptychographic iterative engine

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Chinese Optics Letters 2024年第5期22卷 1-7页

作者：吴丽青齐乃杰昌成成陶华何小亮刘诚朱健强 Key Laboratory of High Power laser and physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China National Laboratory on High Power laser and physics China Academy of Engineering PhysicsChinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

Diffraction intensities of the 3D ptychographic iterative engine(3PIE)were written as a set of linear equations of the selfcorrelations of Fourier components of all sample slices,and an effective computing method was developed to solve these linear equations for the transmission functions of all sample slices *** both theoretical analysis and numerical simulations,this study revealed the underlying physics and mathematics of 3PIE and demonstrated for the first time,to our knowledge,that 3PIE can generate mathematically unique reconstruction even with noisy data.

关键词： 3D imaging 3D ptychographic iterative engine linear equation group unique solution

Refractive index sensing based on a twisted nano-kirigami metasurface

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Photonics Research 2024年第2期12卷 218-225页

作者： SHUQI QIAO XIAOCHEN ZHANG QINGHUA LIANG YANG WANG CHANG-YIN JI XIAOWEI LI LAN JIANG SHUAI FENG HONGLIAN GUO JIAFANG LI School of Science Minzu University of ChinaBeijing 100081China Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(Ministry of Education) Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China laser micro/Nano Fabrication Laboratory School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China

Plasmonic sensing technology has attracted considerable attention for high sensitivity due to the ability to effectively localize and manipulate *** this study,we demonstrate a refractive index(RI)sensing scheme based on open-loop twisted meta-molecule arrays using the versatile nano-kirigami *** sensing has the features of a small footprint,flexible control,and simple *** engineering the morphology of meta-molecules or the RI of the ambient medium,the chiral surface lattice resonances can be significantly enhanced,and the wavelength,intensity,and sign of circular dichroism(CD)can be flexibly *** the relation between the wavelength of the CD peak and the RI of the superstrate,the RI sensor achieves a sensitivity of 1133 nm/***,we analyze these chiroptical responses by performing electromagnetic multipolar decomposition and electric field *** study may serve as an ideal platform for applications of RI measurement and provide new insights into the manipulation of chiral light–matter interactions.

关键词： twisted chiral index

Accelerated generation of holograms with ultra-low memory symmetrically high-compressed look-up table

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Chinese physics B 2024年第4期33卷 466-471页

作者：杨燕朱建英孙敏远毕勇 Applied laser Research Center Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to *** paper presents a hologram generation method,i.e.,a symmetrically high-compressed look-up table method,which can reduce memory usage by50%.In offline computing,half of the basic horizontal and vertical modulation factors are stored,halving the memory requirements without affecting inline ***,its potential extends to various holographic applications,including the production of optical diffraction elements.

关键词： computergenerated hologram look-up table holography

Analytical solution to incident angle quasi-phase-matching engineering for second harmonic generation in a periodic-poled lithium niobate crystal

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Chinese physics B 2024年第2期33卷 115-123页

作者：洪丽红邱雅婷李晓霓陈宝琴李志远 State Key Laboratory of High Field laser physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China School of physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

Phase matching or quasi-phase matching(QPM)is of significant importance to the conversion efficiency of second harmonic generation(SHG)in artificial nonlinear crystals like lithium niobate(LN)crystal or microstructured nonlinear crystals like periodic-poled lithium niobate(PPLN)*** this paper,we propose and show that the incident angle of pump laser light can be harnessed as an alternative versatile tool to engineer QPM for high-efficiency SHG in a PPLN crystal,in addition to conventional means of period adjusting or temperature tuning.A rigorous model is established and analytical solution of the nonlinear conversion efficiency under the small and large signal approximation theory is obtained at different incident *** variation of phase mismatching and walk-off length with incident angle or incident wavelength are also *** simulations for a PPLN crystal with first order QPM structure are used to confirm our theoretical predictions based on the exact analytical solution of the general large-signal *** results show that the narrow-band tunable SHG output covers a range of 532 nm–552.8 nm at the ideal incident angle from 0°to 90°.This theoretical scheme,fully considering the reflection and transmission at the air-crystal interface,would offer an efficient theoretical system to evaluate the nonlinear frequency conversion and help to obtain the maximum SHG conversion efficiency by selecting an optimum incident wavelength and incident angle in a specially designed PPLN crystal,which would be very helpful for the design of tunable narrow-band pulse nanosecond,picosecond,and femtosecond laser devices via PPLN and other microstructured LN crystals.

关键词： nonlinear frequency conversion transmission reflection lithium niobate

Synergic action of linear dispersion, second-order nonlinearity, and third-order nonlinearity in shaping the spectral profile of a femtosecond pulse transporting in a lithium niobate crystal

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Photonics Research 2024年第4期12卷 774-783页

作者： LIHONG HONG YUANYUAN LIU ZHI-YUAN LI State Key Laboratory of High Field laser physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China School of physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

We present a detailed theoretical and numerical analysis on the temporal-spectral-spatial evolution of a highpeak-power femtosecond laser pulse in two sets of systems:a pure lithium niobate(LN)plate and a periodically poled lithium niobate(PPLN)*** develop a modified unidimensional pulse propagation model that considers all the prominent linear and nonlinear processes and carried out the simulation process based on an improved split-step Fourier transformation *** theoretically analyze the synergic action of the linear dispersion effect,the second-order nonlinearity(2nd-NL)second-harmonic generation(SHG)effect,and the third-order nonlinearity(3rd-NL)self-phase modulation(SPM)effect,and clarify the physical mechanism underlying the peculiar and diverse spectral broadening patterns previously reported in LN and PPLN thin plate *** analysis and discussion provides a deeper insight into the synergetic contribution of these linear and nonlinear effects brought about by the interaction of a femtosecond laser pulse with the LN nonlinear crystal and helps to draw a picture to fully understand these fruitful optical physical processes,phenomena,and laws.

关键词： pulse nonlinearity lithium