中文说明：涉及到三个followingMatlab代码：1-Transfermatrix形式主义的光栅计算光栅trasmissivity，发现利用传输矩阵blochmodes。2 - Analyticalsolutions耦合模式方程：计算forwardand落后传播光栅内波场分布。3- Transfermatrix形式主义的光栅有缺陷和增益Bragggratings组成alongthe传播方向的折射率的周期性扰动。这种调制可以通过材料的折射率不同（在自由空间结构）的alternatinglayers获得通过调制波导的横向尺寸或甚至核心指数。
English Description：
The three followingMatlab codes related to:1 -Transfermatrix formalism for gratings calculates grating trasmissivity and finds blochmodes using transfer matrix.2 - Analyticalsolutions to coupled mode equations: calculates field distributions of forwardand backward propagating waves inside the grating.3- Transfermatrix formalism for gratings with defects and gainBragggratings are composed of a periodic perturbation of the refractive index alongthe propagation direction. Such a modulation may be obtained by alternatinglayers of material with different refractive indices (in a free space structure)of by modulating the waveguide lateral dimensions or even the core index.