光丝激光在大气中的传输及中红外波谱特性  

Propagation and Mid-infrared Spectrum Characteristics of Optical Filament Laser in the Atmosphere

作　　者：冯志芳 郝婷 刘勋[2] 刘丽娜 李维[2] 舒小芳 刘渊 FENG Zhi-fang;HAO Ting;LIU Xun;LIU Li-na;LI Wei;SHU Xiao-fang;LIU Yuan(Shanxi Center of Technology Innovation for Light Manipulations and Applications,School of Applied Science,Taiyuan University of Science and Technology,Taiyuan 030024,China;Bejing Institute of Space Mechanics and Electricity,China Academy of Space Technology,Beijing 100094,China;Beijing Academy of Quantum Information Sciences,Beijing,100088,China)

机构地区：[1]太原科技大学应用科学学院,山西省光场调控与融合应用技术创新中心,山西太原030024 [2]中国空间技术研究院、北京空间机电研究所,北京100094 [3]北京量子信息科学研究院,北京100088

出　　处：《量子光学学报》2024年第2期108-120,共13页Journal of Quantum Optics

基　　金：国家自然科学基金项目(12004043,12174034);山西省基础研究计划项目(202203021211192);山西省高等学校科技创新项目(2022L321)。

摘　　要：本文通过数值模拟,利用大气分层模型,研究了强飞秒激光脉冲在距地面1 km以内不同高度处产生光丝,分析了压强、束腰宽度、脉宽以及散射介质的衰减对光丝传输特性和超连续波谱的影响。结果表明,压强的微小变化导致光丝特性的显著变化,从而直接影响超连续波谱的特性。在不同束宽和脉宽下,等离子体丝激发的波谱覆盖了整个可见光波长范围,并延伸到中红外波段,适当地减小束宽和脉宽,可以增强波谱强度和扩展红移截止波长,并且波谱的强度与光丝的长度及稳定性有关,而波谱的红移由光丝的动力学特性决定。散射介质(包括雨滴、雾和气溶胶)对光丝传输特性有较大的影响,但当初始参数选取合适时,衰减对超连续波谱中的中红外波谱强度和展宽的影响是比较小的。此研究为利用中红外波谱探测不同高度处大气污染物成分提供了重要的理论依据。The propagation of intense femtosecond laser pulses in air involves many linear and nonlinear effects,such as diffraction,dispersion,Kerr self-focusing,multiphoton ionization,etc.When the Kerr self-focusing effect and the plasma defocusing effect reach a dynamic equilibrium,a high-intensity"optical filament"is generated.The properties of filamentation have attracted significant attention owing to many interesting phenomena,such as conical emission,third-order harmonic generation,and supercontinuum(SC)radiation.Specifically,the SC spectra induced by filaments undergo a significant extension covering a wide range from the UV to the mid-IR and attracts considerable interest for its potential application in remote sensing detection of atmospheric pollution.Therefore,it is of great significance to explore the propagation of filament and the characteristics of mid-infrared spectral in complex atmospheric environments.Based on the(3D+1)dimensional nonlinear Schr?dinger(NLS)equation,the transmission characteristics of femtosecond pulses in air are described.Firstly,under the slowly varying envelope approximation,we use the evolution of the cylindrically symmetric linearly polarized laser electric field along the propagation axis z to describe the propagation dynamics of femtosecond laser pulses in air.Secondly,the time Fourier transform and the spatial Crank-Nicholson difference scheme are used to numerically solve the coupling equation.Finally,by adjusting the laser pulse input parameters(such as input power,waist width and pulse width)and the focal length of the lens,the filaments are generated by intense femtosecond laser pulses at different heights within 1 km from the ground.In this paper,using atmospheric stratification model and numerically analyzing that pressure,beam waist width,pulse width and attenuation of scattering medium influence on the transmission of the filamentation and the characteristics of supercontinuum spectrum.The results show that:Small changes in pressure lead to significant changes in the cha

关 键 词：强飞秒激光脉冲 中红外波谱 压强 散射介质 光丝 

分 类 号：O437[机械工程—光学工程]