亚波长波导光栅导模共振研究

弱调制介质光栅可等效为平板波导,经其衍射的高级次子波与波导模式耦合时,形成导模 共振。由高级子波在介质光栅中的光程及菲涅耳相移,导出了垂直入射时弱调制介质光栅共振位置的解析表达式,其预测结果和严格耦合波理论所得值一致。导模共振对入射波参数和光栅参数极为敏感,具有窄带效应,可用来制作窄带滤波片。

Research on Guided-Mode Resonance for Sub-Wavelength Waveguide Grating

Weak modulated dielectric grating can be equivalent to planar waveguide. When it diffracted high-order spatial sub-wave is coupled with waveguide mode, a guided mode resonance is formed. An analytical expression for the resonant position of weak modulated dielectric grating at normal incidence is derived from the optical path of high-order sub-wave in dielectric grating and Fresnel phase-shifting. Its predicted results are consistent with strict coupling wave theory. When guided mode resonance occurs, the incident wave parameters and grating parameters are very sensitive. It has a narrow-band effect and can be used to fabricate narrow-band filters.