在非均匀应变场的作用下,布拉格光纤光栅的主要参数有效折射率和光栅周期都会发生非均匀的变化,导致光纤光栅的反射光光谱结构发生变化。在光波导耦合模理论的基础上,建立了布拉格光纤光栅在非均匀应变场下反射光谱的分析数学模型,利用龙格 库塔法对其进行了数值求解。给出了几种典型应变场下的布拉格光纤光栅的反射光谱,并分析了它们的特点。 Under the effect of non-uniform strain field, the main parameters of Bragg fiber grating, such as effective refractive index and grating period, all change non-uniformly, which leads to the change of the spectral structure of the reflected light of FBG. Based on the optical waveguide coupling mode theory, the analytical mathematic model of Bragg fiber grating under non-uniform strain field was established and solved numerically by Runge-Kutta method. The reflection spectra of Bragg gratings in several typical strain fields are given and their characteristics are analyzed.