基于一维光子晶体理论，提出了一种级联薄膜玻璃腔结构的平顶偏振滤波器。给出了具体的设计实例，透射窗口处P偏振光的透射率的最小值大于99.6%，S偏振光的透射率最大在0.1%左右，且P偏振光的各透射窗口的中心频率符合国际电信联盟(ITU)标准。在此基础上，系统研究了该结构各介质膜层参数（包括固体介质腔）以及入射角对透射谱性能，如矩形度、占空比和频率间隔等的影响。该滤波器不但结构简单，易于实现，且在高透射P偏振光的同时能很好地截止S偏振光，在波分复用系统中有一定的应用价值。

Based on the theory of one-dimensional photonic crystal (1DPC), a flat-top polarization filter composed of cascaded thin-film glass cavities is proposed. A detailed design example is also given. The value of transmittance of P polarized light at transmittance window is higher than 99.6% and the maximum value of transmittance of S polarized light is about 0.1%. The center-frequency of transmittance windows for P polarized light accords with the ITU standard. On this basis, the influence of structural parameters of each reflecting film (including glass cavity) and incident angle on spectral performance such as rectangle degree, duty cycle and frequency spacing are investigated systematically. The proposed filter structure not only is very simple and easy to accomplish but also has high transmittance for P polarized light and good cut-off characteristic for S polarized light. It will have some applications in wavelength division multiplexing systems.