多个光波导微环谐振器的组合可扩展自由光谱范围和改善滤波特性。推导了串联双微环谐振器中两个微环与直波导的耦合系数不限定为相同时的理想耦合条件, 针对无损耗情况时光从与小环耦合的直波导入射的情形, 计算了理想耦合条件下主谐振峰带宽、形状因子以及伪模的峰值透射率随耦合系数变化的情况, 显示了耦合系数对滤波特性影响的规律。计算分析表明, 当两个微环与直波导的耦合系数不相等时, 可以取得较为均衡的良好滤波特性, 同时有更多的设计灵活性。

Compound of several optical waveguide microring resonators can extend the free spectral range and improve the filtering properties. For series coupled two-microring resonators, the perfect coupling condition is derived when the coupling coefficients between the two rings and the straight waveguides are not limited to be equal. When the light is input through the straight waveguide coupled with the smaller ring under perfect coupling condition, the changing of main resonance peak bandwidth, shape factor, and peak transmittance of the spurious modes with the coupling coefficients are calculated. The influence patterns of the coupling coefficients on these filtering characteristics are demonstrated. Calculation and analysis show that when the coupling coefficients between the two rings and the straight waveguides are different, balanced filtering characteristics can be realized, and more flexibility of design can be provided.