中文摘要：

从理论上研究了级联双折射光纤环镜滤波器的滤波特性，给出加隔离器与不加隔离器两种不同结构的串联双环镜滤波器透射光强的表达式，并对于两个环镜取不同的周期比时的滤波特性进行了数值模拟和分析．得出串联环镜滤波效果与级联顺序无关，光隔离器对滤波效果不会产生影响，只是增加了插入损耗．通过级联和改变两个环镜的双折射光纤长度比，可以获得不同的滤波效果．最后给出了多个环镜直接级联后透射光强的通项表达式，通过对通项式的理论分析可以设计不同的滤波器．

英文摘要：

Cascade filter characteristics of high birefringence fiber loop mirror are studied theoretically, transmission power expressions of two kinds of series loop mirrors that connected with fiber optic isolator or not are given, and the filter characteristics of the two loop mirrors with di,fferent periodic ratio are numerically simulated and analyzed. There is no ralation ship between filter effect and the cascade sequence of two loop mirrors,and the filter effect is not affected by the fiber optic isolator which only increases the insertion loss. Different filter effect can be obtained by cascading and changing birefringence fiber＇s length ratio of two fiber loop mirrors. The general expression of transmission optical power for cascade high birefringence fiber loop mirrors is given, and different filter can be designed by analyzing the general expression theoretically.