为了改善常规马赫曾德尔干涉仪(MZI)型滤波器的输出特性， 提出了一种由双耦合器和单模光纤构成的“8”字形谐振环，将该光纤谐振环与一个3 dB光纤方向耦合器相结合，利用光纤谐振环反馈回路引入的相位调节效应，选择合适的谐振环耦合角，设计出一种基于对称结构的光纤谐振环梳状滤波器，具有平坦滤波响应的输出光谱。与普通MZI型梳状滤波器和双级级联MZI型梳状滤波器相比，阻带抑制和过渡带滚降特性明显加强；与不对称结构的光纤谐振环辅助MZI型梳状滤波器相比，在考虑传输损耗的情况下，相干涉的两束光信号不存在幅度差异，降低了传输损耗对梳状滤波器消光特性的影响。

In order to improve the transmission performance of the conventional Mach-Zehnder interferometer (MZI), a novel interleaver combining ring resonator with a single fiber coupler of 3 dB direction is proposed. The ring resonator shaped like an “8” form is based on double-coupler and single-mode fiber. Based on the phase modification provided by the ring resonator, a flatness filtering response is obtained by optimizing the coupling angle of resonator. Compared with the traditional MZI-interleaver and two-stage MZI-interleaver, the isolation in stopband and the rolloff in transition band are strengthened. Compared with the interleaver based on an asymmetrical MZI with a resonator in one arm, there is no difference between the intensities of two coherent light beams in the condition of considering the influence of the propagation loss. Theoretical analysis shows that the influence of the propagation loss on extinction ratio can be effectively reduced by proposed interleaver.