三层亚波长光栅结构的透射特性

设计了一种具有三层结构的亚波长金属光栅，采用时域有限差分（FDTD）法对所设计的三层光栅结构进行仿真计算．与单层金属光栅相比，这种三层的光栅结构具有更好的滤波效果，其透射光谱中峰值可达77％，且能很好地抑制高波段的透射率．分析了各几何参数对所设计的光栅结构透射特性的影响，尤其是对透射光谱中0值位置的影响．结果表明0值位置主要受光栅缝宽、介质层高度和介质折射率的影响，而与金属层光栅的高度无关．其影响规律为偏振滤波器的设计提供了参考．

Transmission Properties of Triple-Layer Subwavelength Grating

A type of triple-layer subwavelength metallic grating structure was designed and simulated uti- lizing finite-difference time-domain （FDTD） method. Compared with single metallic grating, the new grating structure can achieve better filtering result. For the triple-layer grating transmission spectrum, the peak transmission efficiency is 77% and the transmission of higher wavelength is well suppressed. The in- fluence of geometrical parameters on transmission, especially on the zero position of the spectrum, was investigated. The results demonstrate that the zero position is affected by grating width, dielectric layer thickness and dielectric refractive index, but is independent of metallic layer thickness. The influence rules offer a useful reference for the design of polarizing filters.