采用多层介质的离散传输线模型表征光纤光栅响应特性 ,并利用数字信号处理方法对光纤光栅的相位特性进行了分析 ,研究了用于密集波分复用窄带滤波的变迹光纤光栅的带内色散特性 ,表明对称变迹光纤光栅的幅度响应与相位响应之间满足希尔伯特变换关系 ,幅度响应越接近理想的矩形 ,带内色散越大。并采用耦合模理论数值计算了对称变迹的光纤光栅的反射相位响应和带内群时延情况 ,验证了分析结果 The discrete transmission line model of multi-layer medium is used to characterize the response of the fiber grating. The phase characteristics of the fiber grating are analyzed by using the digital signal processing method. In-band dispersion of the apodized fiber grating for dense wavelength division multiplexing It shows that the amplitude response and phase response of symmetric apodized FBG satisfy the Hilbert transform relationship, the closer the amplitude response is to the ideal rectangle, the larger the in-band dispersion. The phase response of the symmetric apodized FBG and the delay of the in-band group were calculated by using the coupled-mode theory. The results of the analysis