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External focusing dependence of spatial distribution of air lasers during femtosecond laser filamentation in air

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Chinese Optics Letters 2021年第8期19卷 18-22页

作者： Jiayun Xue Hui Gao Nan Zhang Lu Sun Lie Lin Weiwei Liu Institute of Modern Optics Tianjin Key Laboratory of Micro-Scale Optical Information Science and TechnologyNankai UniversityTianjin 300350China School of Physical Science and Technology Tiangong UniversityTianjin 300387China

The spatial distribution of the forward-propagating amplified spontaneous emission(ASE) of nitrogen molecular ions during femtosecond laser filamentation in air is studied via numerical simulations. The results suggest that the divergence angle and signal intensity are extremely sensitive to the external focal length. Concurrently, we show that the optical Kerr effect plays a significant role in concentrating the directivity of ASE signals, particularly in cases of loose focusing. Furthermore,the simulations demonstrate that ASE signals are enhanced for a tight focus, although the corresponding filament length is shorter. The main physical mechanism underlying this process is the competition between the plasma defocusing and optical Kerr effects. The result is important for filamentation-based light detection and ranging applied to remote sensing.

关键词： air laser amplified spontaneous emission femtosecond laser filamentation

Orientation-dependent depolarization of supercontinuum in BaF2 crystal

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Chinese Physics B 2020年第1期29卷 324-328页

作者： Zi-Xi Li Cheng Gong Tian-Jiao Shao Lin-Qiang Hua Xue-Bin Bian Xiao-Jun Liu State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

We present a systematic investigation of the depolarization properties of a supercontinuum accompanied with femtosecond laser filamentation in barium fluoride(BaF2)*** is found that the depolarization of the supercontinuum depends strongly on the crystal orientations with respect to the incident laser *** most crystal orientations,the depolarization of the supercontinuum rises with the increase of the input laser energies and finally *** at 45°,the depolarization of the supercontinuum is not changed and keeps nearly negligible with the increase of the input laser *** peculiar depolarization properties of the supercontinuum can be ascribed to the orientation dependence of the cross-polarized wave(XPW)generation and ionization-induced plasma scattering in the BaF2 crystal.

关键词： femtosecond laser filamentation supercontinuum depolarization

Pulse repetition rate effect on the plasma inside femtosecond laser filament in air

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Chinese Optics Letters 2024年第1期22卷 135-140页

作者：尹富康王铁军刘尧香龙娟魏迎霞朱斌周凯南冷雨欣 State Key Laboratory of High Field laser Physics Shanghai Institute of Optics and Fine Mechanics and CAS Center for Excellence in Ultra-intense Laser ScienceChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China laser Fusion Research Center and Science&Technology on Plasma Physics Laboratory China Academy of Engineering PhysicsMianyang 621999China

The characteristics of plasmas play an important role in femtosecond laser filament-based *** analysis is used to experimentally investigate the plasma density and its temperature of the air filament under different pulse repetition *** our experiments,the measured average plasma density of the filament is 1.54×10^(17)cm^(-3)and the temperature of the plasma is about 5100 K under 100 Hz pulse repetition *** plasma density decreases to1.43×10^(17)cm^(-3)and the temperature increases to 6230 K as the pulse repetition rate increases to 1000 *** experimental observation agrees with the numerical simulation by solving the nonlinear Schr?dinger equations with repetition rate related“low density hole”correction.

关键词： femtosecond laser filamentation cumulative effects electron density

Rapid diagnosis of femtosecond laser filament by single laser shot-induced acoustic pulses[Invited]

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Chinese Optics Letters 2024年第9期22卷 48-53页

作者： Binpeng Shang Nan Zhang Zhi Zhang Pengfei Qi Lanjun Guo Lie Lin Weiwei Liu Institute of Modern Optics Eye InstituteNankai UniversityTianjin 300350China Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350China

Due to the promising applications of femtosecond laser filamentation in remote sensing,great demands exist for diagnosing the spatiotemporal dynamics of ***,until now,the rapid and accurate diagnosis of a femtosecond laser filament remains a severe ***,a novel filament diagnosing method is proposed,which can measure the longitudinal spatial distribution of the filament by a single laser shot-induced acoustic *** dependences of the point-like plasma acoustic emission on the detection distance and angle are obtained *** results indicate that the temporal profile of the acoustic wave is independent of the detection distance and detection *** the measured relation among the acoustic emission and the detection distance and angle,a single measurement of the acoustic emission generated by a single laser pulse can diagnose the spatial distribution of the laser filament through the Wiener filter deconvolution(WFD)*** results obtained by this method are in good agreement with those of traditional point-by-point acoustic diagnosis *** findings provide a new solution and idea for the rapid diagnosis of filament,thereby laying a firm foundation for femtosecond laser filament-based promising applications.

关键词： femtosecond laser filamentation diagnosis single laser shot acoustic emission Wiener filter deconvolution

Pulse repetition-rate effect on the intensity inside a femtosecond laser filament in air

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High Power laser Science and Engineering 2023年第4期11卷 17-24页

作者： Fukang Yin Juan Long Yaoxiang Liu Yingxia Wei Bin Zhu Kainan Zhou Tie-Jun Wang Yuxin Leng Ruxin Li State Key Laboratory of High Field laser Physics Shanghai Institute of Optics and Fine Mechanics and CAS Center for Excellence in Ultra-intense Laser ScienceChinese Academy of SciencesShanghaiChina Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina laser Fusion Research Center and Science&Technology on Plasma Physics Laboratory China Academy of Engineering PhysicsMianyangChina

As intense,ultrashort,kHz-repetition-rate laser systems become commercially available,pulse cumulative effects are critical for laser filament-based *** this work,the pulse repetition-rate effect on femtosecond laser filamentation in air was investigated both numerically and *** pulse repetition-rate effect has negligible influence at the leading edge of the *** intensity enhancement from a high-repetition pulse is observed at the peak and tailing edge of the laser *** the repetition rate of the laser pulses increases from 100 to 1000 Hz,the length of the filament extends and the intensity inside the filament increases.A physical picture based on the pulse repetition-rate dependent‘low-density hole’effect on filamentation is proposed to explain the obtained results well.

关键词： clamping intensity cumulative effects femtosecond laser filamentation

Polarization dependent clamping intensity inside a femtosecond filament in air

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Chinese Optics Letters 2021年第10期19卷 97-102页

作者： Hao Guo Xiang Dong Tie-Jun Wang Xuan Zhang Na Chen Fukang Yin Yihai Wang Lingang Zhang Haiyi Sun Jun Liu Jiansheng Liu Baifei Shen Olga Kosareva Yuxin Leng Ruxin Li State Key Laboratory of High Field laser Physics and CAS Center for Excellence in Ultra-intense laser Science Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Department of Physics College of Arts and ScienceUniversity of Colorado BoulderBoulderCO 80309USA College of Physics Guizhou UniversityGuiyang 550025China Department of Physics Shanghai Normal UniversityShanghai 200234China Physics Faculty Lomonosov Moscow State UniversityMoscow 119991Russia

laser polarization and its intensity inside a filament core play an important role in filament-based ***,polarization dependent clamping intensity inside filaments has been overlooked to interpret the polarization-related filamentation ***,we report on experimental and numerical investigations of polarization dependent clamping intensity inside a femtosecond filament in *** adjusting the initial polarization from linear to circular,the clamping intensity is increased by 1.36 times when using a 30 cm focal length lens for *** results indicate that clamping intensity inside the filament is sensitive to laser polarization,which has to be considered to fully understand polarizationrelated phenomena.

关键词： femtosecond laser filamentation clamping intensity polarization

Time-resolved measurements of electron density and plasma diameter of 1 kHz femtosecond laser filament in air

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Chinese Optics Letters 2022年第9期20卷 73-78页

作者： Hengyi Zheng Fukang Yin Tie-Jun Wang Yaoxiang Liu Yingxia Wei Bin Zhu Kainan Zhou Yuxin Leng State Key Laboratory of High Field laser Physics Shanghai Institute of Optics and Fine Mechanics and CAS Center for Excellence in Ultra-intense Laser ScienceChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China laser Fusion Research Center and Science&Technology on Plasma Physics Laboratory China Academy of Engineering PhysicsMianyang 621999China

The temporal evolutions of electron density and plasma diameter of 1 kHz femtosecond laser filament in air are experimentally investigated by utilizing a pump-probe longitudinal diffraction method.A model based on scalar diffraction theory is proposed to extract the spatial phase shift of the probe pulse from the diffraction patterns by the laser air plasma *** hydrodynamic effect on plasma evolution at 1 kHz filament is included and *** measured initial peak electron density of~10^(18)cm^(-3) in our experimental conditions decays rapidly by nearly two orders of magnitude within200 ***,the plasma channel size rises from 90μm to 120μm as the delay time *** experimental observation is in agreement with numerical simulation results by solving the rate equations of the charged particles.

关键词： femtosecond laser filamentation electron density diffraction

Remote sensing of trace Na element in sea salt aerosol with a sensitivity level of 10 pg/m^(3)[Invited]

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Chinese Optics Letters 2024年第9期22卷 26-30页

作者： Yuezheng Wang Jiayun Xue Nan Zhang Lu Sun Binpeng Shang Jiewei Guo Zhi Zhang Pengfei Qi Lie Lin Weiwei Liu Institute of Modern Optics Eye InstituteNankai UniversityTianjin 300350China Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350China School of Integrated Circuit Science and Engineering Tianjin University of TechnologyTianjin 300384China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350China

We have developed a remote sea salt aerosol fluorescence spectroscopy system integrating a high-power industrial-grade femtosecond laser to enhance detection sensitivity and precision in complex *** system successfully detects sea salt aerosol particles,achieving a detection limit of 0.015 ng/m^(3) for neutral Na element(Na I)at 589 nm,with a detection range of 30 *** findings demonstrate significant improvements in remote aerosol monitoring,addressing previous challenges in long-range and high-precision sensing with a detection accuracy previously unattainable below 10 ng/m^(3).

关键词： femtosecond laser filamentation sea salt aerosol remote sensing amplified spontaneous emission