采用单环微谐振器的光滤波器特性及其局限性

Characteristics and Limitations of Optical Filters Employing Single-ring Microresonators

对采用单环微谐振器的光滤波器的特性进行了分析。在给出的传递函数和相关特性公式基础上 ,分析了出 /入环光耦合系数与通带带宽和通带消光比间的关系 ,指出了它们之间、以及与自由谱范围间存在的相互约束 ;分析并给出了单环光滤波器的通带带宽比例 ,带宽比例值不依赖于任何器件结构参数 ,是限制单环微谐振器作为实用光滤波器的主要因素 ;分析了存在于微环中光的损耗对单环光滤波器输出的影响 ,小的光损耗即会导致滤波响应的巨大衰减 ,大的光损耗则更是会导致带宽的展宽和带宽比例值的增大。

The transfer function was presented first and then other related formula was derived. The influence of the into-/out-of-ring coupling coefficients on the bandwidth and extinction ratio of the spectral band was investigated and the design restriction among them and free-spectral range was discussed. The analytical results show the bandwidth ratio of the spectral passband is almost independent of any structure parameters of the single-ring microresonator when the into-/out-of-ring coupling coefficients are very small. The calculated values of bandwidth ratios indicate that the bandwidth ratio is the key issue which limits the usage of the single-ring microresonator as a practical optical filter. The influence of optical loss is also analyzed. Low optical loss will cause sharp attenuation of the filtering response and severe optical loss also can widen the bandwidth and increase the bandwidth ratio.