基于共振异常的消偏振型窄带滤波器分析

Analysis of Nonpolarizing Narrow-Band Filters Based on Resonant Anomaly

亚波长光栅因光栅参量的不同而具有不同的衍射特性 ,通过对亚波长光栅参量的合理设计来实现消偏振窄带滤波是一种新的方法与途径。首先分析了基于共振异常的窄带滤波的物理机制及存在条件 ,讨论了二维亚波长光栅实现消偏振窄带滤波的可能性。然后 ,利用严格模式理论进行了计算模拟 ,其计算结果与导波理论所得结果基本吻合 ,其衍射特性表现出周期性共振异常 敏感的角度依赖性和波长依赖性。最后 ,讨论了由工艺误差对滤波特性所带来的影响 ,为具体工艺制作提供了一定的指导。

Subwavelength gratings with different grating parameter have different diffractive properties, and realization of nonpolarizing narrow-band filtering by reasonably designing the parameter of subwavelength grating is a novel method and approach. Based on resonant anomaly, physical mechanism of narrow-band filtering and its condition was analyzed, and probability for realization of nonpolarizing narrow-band filtering in two-dimensional subwavelength gratings was discussed. Using rigorous modal theory, its simulation results were consistent with those of guided-wave theory, in which location of resonant anomaly appear periodically and diffraction efficiency is very sensitive to not only incidence angle but also wavelength. At last, fabrication errors effecting diffractive properties were analysed, which, to some degree, are useful to concrete fabrication.