高斯光束在克尔型非线性介质中演化的奇异特性  

Singularity Feature of Gaussian Beam Propagating in Absorptive Kerr Medium

作　　者：刘雅洁[1] 冯启元[2] 

机构地区：[1]嘉兴学院物理教研室,嘉兴314001 [2]内蒙古大学物理系,呼和浩特010021

出　　处：《光学学报》2006年第12期1861-1865,共5页Acta Optica Sinica

摘　　要：由光束在克尔型吸收介质中传输的非线性薛定谔方程出发,推导了高斯光束注入介质后满足的耦合方程。在不考虑高阶展开项的前提下,将介质分为无吸收、有吸收两种情况,对脉冲的腰斑半径的演化进行了解析分析,得到注入克尔型非线性介质中的高斯光束,形成“孤波”必须满足光束在束腰处注入,介质没有吸收的条件;当考虑高阶展开项时,通过数值分析发现,无论介质是否存在吸收,光束传输不存在“孤波”形式,而是在注入强度的控制之下。当注入强度较小时,自聚焦过程是它的一个主要结果。但当注入脉冲的强度增加后,除了腰斑半径不为零的区间增加,光束仍保持聚焦的正常现象之外,存在一个阈值。当注入强度超过此阈值时,腰斑半径随着距离的增加而快速增加,聚焦趋势根本就不存在。From the nonlinear Schrodinger equation of beam propagating in Kerr absorbing medium, a set of evolution equations describing Gaussian beam waist radius have bean deduced, As taking no account of high order expanded term, the evolution of beam waist radius in medium without or with absorption has bean analyzed theoretically. And the result is that the beams would form solitary wave only as inputting at waist, no absorption are acquired. As taking account of high order expanded terms, there exists no solitary wave in beam propagation by numerical analysis without or with absorption, and the beams are controlled by input intensity. When input intensity is smaller, the beam would behave self-focusing only. Along with the increasing of input intensity, there is a threshold. As the input intensity is below this threshold, the input beam behaves self-focusing still; but as the input intensity surpasses this threshold, the input beam behaves diffraction strongly, no self-focusing occurs at all.

关 键 词：高斯光束 克尔型吸收介质 非线性薛定谔方程 腰斑半径 自聚焦 

分 类 号：O437.5[机械工程—光学工程]