通过在失配光纤消逝场间的耦合作用中引入光栅调制扰动效应,推导出用于解释光栅辅助耦合器响应特征的耦合模方程,在此基础上全面分析了两光纤间的失配度对上下话路滤波性能的影响.采用非对称熔融预拉锥工艺,调整光纤的结构参数,制成了性能良好的光栅辅助耦合器,实验测试结果与理论计算符合得很好. By introducing the effect of grating modulation perturbation into the coupling effect of the evanescent field of the mismatched fiber, a coupled-mode equation for explaining the response characteristics of the grating auxiliary coupler is deduced. Based on the analysis, the mismatch between the two fibers is analyzed. The influence of the filter performance of the speech channel.The asymmetric melting pre-taper process is adopted to adjust the structural parameters of the optical fiber to make the grating auxiliary coupler with good performance. The experimental test results are in good agreement with the theoretical calculation.