摘要
采用数值模拟方法研究了大气非线性自聚焦效应对艾里光束上行大气传输特性和光束质量的影响,结果表明:大气自聚焦效应随着艾里光束指数截断因子的增大而增强,并会导致艾里光束的实际焦点向靶面移动。采用预散焦方法可使靶面上的光束始终保持艾里轮廓,同时可使靶面光强得到显著提高。本文得到了预散焦的焦距公式,并证实了其有效性。研究发现:预散焦后,即使光束功率远远超过了自聚焦临界功率,非均匀大气的自聚焦效应也不会破坏艾里光束的自加速特性,有助于地基激光束避开障碍物,清除空间碎片。在相同的功率下,艾里光束相比高斯光束在碎片靶面上有更高光强,并且艾里光束具有更强的抵抗自聚焦效应的能力。因此,艾里光束比高斯光束更适合地基激光对空间碎片的清除。
Objective Ground-based laser systems can remove centimeter-scale space debris in the low-Earth orbit region.However,as the high-power laser beam propagates through the atmosphere,it encounters significant challenges.When the beam’s power exceeds the atmosphere’s critical power for the self-focusing effect,the beam quality at the target diminishes due to this nonlinear effect.Interestingly,Airy beams exhibit self-accelerating characteristics,making them potentially advantageous for bypassing obstacles.However,in homogeneous self-focusing media,an Airy beam can lose its self-accelerating traits if its power is exceedingly high.This leads to pressing inquiries:Does the nonlinear self-focusing effect in an inhomogeneous atmosphere disrupt the selfaccelerating nature of Airy beams?Is an Airy beam better suited than a Gaussian beam for ground-based laser space debris removal?How to enhance the target quality of Airy beams?Hence,analyzing the influence of nonlinear self-focusing on the attributes and quality of upward-propagating Airy beams in the atmosphere becomes crucial.Methods Under the paraxial approximation,the beam characteristics of diffraction and self-focusing nonlinearity were described via a nonlinear Schrödinger equation.However,solving the nonlinear Schrödinger equation analytically for an Airy beam propagating in the atmosphere is challenging.In this study,the nonlinear Schrödinger equation was solved numerically using the multiphase screen method.As the altitude increased,the nonlinear refractive index decreased,and the nonlinear self-focusing effect became negligible at sufficiently high altitudes.Consequently,an Airy beam that propagated upward in the atmosphere experienced two stages:inhomogeneous atmospheric propagation(comprising both diffraction and self-focusing effects)and free space propagation(with only the diffraction effect).Results and Discussions As the exponential truncation factor of the Airy beams increases,the value of the B integral also increases(Fig.1),indicating a strengthen
作者
罗静
季小玲
李晓庆
Luo Jing;Ji Xiaoling;Li Xiaoqing(College of Physics and Electronic Engineering,Sichuan Normal University,Chengdu 610068,Sichuan,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2024年第5期69-75,共7页
Chinese Journal of Lasers
基金
国家自然科学基金(62375191,61775152)。
关键词
大气光学
艾里光束
非线性自聚焦效应
激光大气传输
传输特性
光束质量
atmospheric optics
Airy beam
nonlinear self-focusing effect
laser beam propagation in the atmosphere
propagation characteristics
beam quality
