BPM_free_space.m - Propagation of a gaussian pulse in free space BPM_free_space.m - 传播的高斯脉冲在自由空间 BPM_triangle.m - Propagation of a gaussian pulse in a triangle index profile waveguide BPM_triangle.m - 传播中的一个三角形折射率分布波导高斯脉冲 BPM_2step.m - Demons