Kerr非线性介质中聚焦像散高斯光束的传输特性  

Propagation characteristics of focused astigmatic Gaussian beams in Kerr nonlinear media

作　　者：胡婧 王欢[1] 季小玲[1] Hu Jing;Wang Huan;Ji Xiao-Ling(Department of Physics and Electronic Engineering,Sichuan Normal University,Chengdu 610068,China)

机构地区：[1]四川师范大学物理与电子工程学院,成都610068

出　　处：《物理学报》2021年第7期147-153,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61775152)资助的课题.

摘　　要：当高功率激光通过Kerr非线性介质传输时,Kerr效应会严重影响激光的传输特性.实际应用中常遇到像散光束.迄今为止,像散光束传输特性的研究大都局限于在线性介质中的传输,而在非线性介质中传输的研究较少,且还未涉及像散激光束通过含光学系统的Kerr非线性介质传输变换的研究.本文主要研究Kerr效应对聚焦光束像散特性和焦移特性的影响,以及聚焦像散高斯光束的自聚焦焦距和光束焦点调控.在光束扩展情况下,推导出了聚焦像散高斯光束在Kerr非线性介质中传输的束宽、束腰位置和焦移的解析公式,研究表明:在自聚焦介质中,随着自聚焦作用增强(如光束功率增强),光束像散越强,但焦移越小;在自散焦介质中,随着自散焦作用增强(如光束功率增强),光束像散越弱,但焦移越大.另一方面,在光束自聚焦情况下,推导出了自聚焦焦距的解析公式,研究表明利用光束像散可以调控光束焦点个数.When a powerful laser beam propagates in a Kerr nonlinear medium,the Kerr effect on the beam propagation characteristics is very significant.The astigmatic laser beams are often encountered in practice.Until now,much work has been carried out on the propagation characteristics of astigmatic laser beams in linear media,but a few researches have been reported about the propagation of astigmatic laser beams through nonlinear media.To the best of our knowledge,the propagation or the transformation of astigmatic laser beams through an optical system in a Kerr nonlinear medium has not been investigated.In this paper,the propagation characteristics of focused astigmatic Gaussian beams in a nonlinear Kerr medium are studied.The Kerr effect on the beam astigmatism and the focal shift of focused astigmatic Gaussian beams are investigated in detail,and the self-focusing focal length and focus control of focused astigmatic Gaussian beams in the Kerr nonlinear medium are also studied.For the beam spreading case,the analytical formula for each of the beam width,the beam waist position,and the focal shift of focused astigmatic Gaussian beams in the Kerr nonlinear medium is derived.It is shown that in the self-focusing medium,as the beam power increases(i.e.the self-focusing effect becomes stronger),the beam astigmatism becomes stronger,but the focal shift decreases.However,in a selfdefocusing medium,as the beam power increases(i.e.the self-defocusing effect becomes stronger),the beam astigmatism becomes weaker,but the focal shift increases.On the other hand,for the beam self-focusing case,the analytical formula of the self-focusing focal length of focused astigmatic Gaussian beams in the Kerr nonlinear medium is derived.It is found that the number of foci can be controlled by applying beam astigmatism.The results obtained in this paper are of theoretical and practical significance.

关 键 词：KERR 效应 像散特性 焦移特性 焦点调控 

分 类 号：O437[机械工程—光学工程]