亚波长介质光栅导模共振研究

从平板波导的本征值方程出发,导出弱调制介质光栅共振位置的表达式,其预测结果与利用严格的耦合波理论所得值一致.对正入射时导模共振产生双反射峰现象进行解释,并就导模共振对入射角和光栅周期敏感性的成因进行了探讨.从薄膜的特征矩阵方程出发,在理论上分析了利用导模共振获得性能良好的反射滤光片的途径.

Research on Guide-Mode Resonance for Sub-Wavelength Dielectric Grating

Weakly modulated dielectric grating can be equivalent to planar waveguide. When diffracted high-order spatial sub-waves are coupled with the leak mode of the grating, guided-mode resonance occurs. In this paper, an analytical expression for the resonant position of weakly modulated dielectric grating is derived from the eigenvalue equation of planar waveguide. Its predicted results are consistent with the rigorous coupled-wave theory. The phenomenon that guided-mode resonance causes double reflection peaks at normal incident is explained for the first time, and the reasons that guide-modes is sensitive to the incident angle and the grating period are also discussed. In addition, the way to get reflection filters with good peculiarities is analyzed theoretically from the equation of characteristic matrix of the thin film