平顶光束经表面有缺陷的厚非线性介质后的光强分布

基于非线性薛定谔方程和分步傅里叶算法, 研究了高功率平顶高斯光束经过厚非线性介质后在自由空间传输的光强演变过程, 详细分析了介质表面缺陷对光强演化规律的影响.研究结果表明, 平顶阶数越大, 光束的自聚焦效果越差, 最大光强点越靠近介质后表面.入射光束的初始场强越强, 介质的厚度和非线性系数越大, 光束的自聚焦越强, 且极值点越靠近介质后表面.介质表面的缺陷使得光束在靠近介质后表面有较大的光强. 并且相位调制型缺陷比振幅调制型缺陷对光强的影响更大. 关键词： 平顶光束 自聚焦 缺陷 光强分布

Intensity distribution of the flat-topped beam propagating through the thick nonlinear medium with defects

Based on the nonlinear Schrödinger equation and Fourier transformation, the intensity distributions of the high power flat-topped beam propagating in the nonlinear medium and the free space are studied. The influences of the defects on medium surface on the intensity evolution of flat-topped light beam in the medium and the free space are analyzed. The results show that the larger the beam order, the poorer the beam self-focusing property is, and the closer to the back surface of the medium the position related to the maximal intensity point is a stronger initial intensity, a thicker medium or a higher nonlinear coefficient will lead to a stronger self-focusing property. The defects on the surface of medium will produce a relatively large intensity, closer to the back surface of medium. The effect of the phase modulated defect on the intensity evolution is greater than that of amplitude modulated defect.