以强激光系统和自聚焦理论的研究为出发点, 主要采用光束传输法和光线追迹法分析了非线性介质下的强激光光束传输过程。并且, 基于适合于非线性介质下光线追迹的亚当斯法和基于梯度信息的光强分布的恢复算法, 仿真模拟出光强与透镜厚度、介质折射率、透镜曲率半径以及入射光束半径的关系; 同时结合光学设计软件, 不仅得出了折射率与光强的乘积与焦点位置的变化关系, 还通过点列图中的数据直观地反映出系统结果的成像质量, 最后对光线追迹法和光束传输法两种光学方法进行了对比分析。仿真分析结果可以判断出系统的哪些部分容易受到自聚焦的影响, 进而可以通过改进某些参数的大小, 减少并消除其不利影响, 找到适合于强激光系统的最优方法。

Based on high intensity laser systems theory and self-focusing research, the nonlinear medium under the beam transmission process was described using the beam propagation method and ray tracing method. Besides, it was found that some ways were suitable for nonlinear medium, such as Adams method under the ray tracing method and recovery algorithm based on gradient information of intensity distribution. Finally, the simulation results revealed the relationship between the light intensity and these factors, including lens thickness, the refractive index of medium, the lens curvature radius and the radius of the incident beam. And combined with optical design software, it not only reflected the relationship between the product of the refractive index and the light intensity and the focus position changes, but also the results of image quality intuitively through the data of spot diagram. And two kinds of main optical methods, the ray tracing method and the beam propagation method, were made for the comparative analysis. According the simulation results, it could be determined that bits of the system was easily affected by self-focusing, so the size of certain parameters could be improved, the adverse effect could be reduced and eliminated, and an optimal method which was suitable for strong laser system could be found.