强激光束在Kerr非线性介质中非傍轴传输研究

强激光束在Kerr非线性介质中非傍轴传输研究

摘要：本文主要是研究强激光束在Kerr非线性介质中非傍轴传输特性。首先从麦克斯韦方程组出发，结合Kerr非线性介质的物构方程，导出光传输波动方程；再在缓变包络近似和标量近似下，利用随动坐标系，导出了非线性非傍轴传输方程；利用变分法得出光束各参量演化的耦合方程。根据非傍轴效应总是小量的特性，结合得出的耦合方程，得到非傍轴迭代方程。最后，具体比较了傍轴与非傍轴情形下激光功率随传输距离的演化过程。结果表明，傍轴条件下，激光功率随传输距离不变；而在1阶非傍轴修正下，激光功率随传输距离振荡变化。
关键词：强激光束；Kerr非线性；非傍轴；变分法；迭代方程

Study on the non-paraxial propagation of intense laser beam in Kerr nonlinear media
 
Abstract: We study the non-paraxial properties of intense laser beam propagating in Kerr nonlinear media. A wave propagation equation is derived from the Maxwell’s equations. Making use of the slowly-varying envelope approximation, the scalar approximation, and the co-moving coordinate system, a non-paraxial equation for intense laser beam propagating in Kerr nonlinear media is obtained. By using variational method to the non-paraxial equation, four coupled equations for beam parameters governing the propagation properties are obtained. Coupled iterative equations are then established since the non-paraxial parameter always keeps smaller than others. Beam power varying with periodic oscillations with first-order nonparaxiality correction while it has no variation along the propagation distance in the paraxial case.

Key words: intense laser beam; Kerr nonlinearity; nonparaxiality; variational method; iterative equations

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