利用偏振光干涉和多光束干涉的原理 ,推导了BGT型交叉复用器的传输函数。分析传输函数发现 ,Gires Tournois腔的反射率越高 ,交叉复用器的 0 .5dB通带带宽越宽 ,隔离度越小 ;反之 ,0 .5dB通带带宽越窄 ,隔离度越大。设计、调试相关实验 ,验证了BGT型交叉复用器性能参量之间的关系。可利用BGT型交叉复用器的这一特性来确定其结构参量 ,也可利用它这一特性来制作可调谐交叉复用器 Using the principle of polarization interference and multi-beam interference, the transfer function of BGT type cross-multiplexers is deduced. The analysis of the transfer function found that the higher the reflectivity of the Gires Tournois cavity, the wider the 0 .5dB passband of the cross-multiplexer and the smaller the isolation. Conversely, the narrower the passband of 0 .5dB, the greater the isolation. Design and debug related experiments, verify the BGT-type cross-multiplexer performance parameters between the relationship. BGT type of cross-multiplexer can be used to determine the characteristics of its structural parameters, but also can use this feature to make tunable cross-multiplexer