将一种矩阵算法拓展应用于数值求解多模耦合模微分方程,并使用该矩阵算法对大模场啁啾光纤光栅的光谱特性进行了理论研究。结果表明,大模场多模光纤光栅因模式的自耦合和互耦合而使反射谱存在多个反射峰,这与单模光纤光栅的反射谱不同。由于光栅周期存在啁啾,大模场光纤光栅的反射峰分裂,且峰值反射率减小。使用高斯切趾函数可使反射峰分裂在一定程度上得到改善。 A matrix algorithm is extended to solve the multi-mode coupled-mode differential equations numerically. The spectral characteristics of the large mode field chirped fiber gratings are studied theoretically. The results show that there are multiple reflection peaks in the reflection spectrum due to the self-coupling and mutual coupling of the mode-mode multimode fiber gratings, which is different from the reflection spectrum of the single-mode fiber grating. Due to the chirp of the grating period, the reflection peak of the large mode field fiber grating splits and the peak reflectivity decreases. The use of the Gaussian apodization function can improve the reflection peak splitting to a certain extent.