1维介质光栅近场及其衍射的FDTD分析

 应用FDTD方法计算了单色平面波斜入射时1维介质光栅的近场，进而求出介质光栅的衍射效率。借助于周期边界条件，整个计算区域为周期结构的一个单元。考虑入射波在两种介质界面上会产生反射和透射，故在总场边界上引入入射波、反射波和透射波。给出了光栅单元截面为矩形和梯形的算例。该方法可用于斜入射情形下具有复杂结构和任意单元截面的介质栅近场及其衍射特性分析。

Analysis on near-field and diffraction problem of 1-D dielectric grating using FDTD method

In this paper, FDTD method incorporated with periodic boundary condition is applied to solve the near fields for dielectric gratings with plane wave illumination. Then the diffraction characteristics of transmission gratings are analyzed. The size of domain to be solved is restricted to a single cell of the dielectric periodic structure. Owing to the presence of interface of dielectric and air, it is required to impose three waves, including incident plane wave, reflected and transmitted waves at the total-scattered field boundary. The method is applied to study the diffraction characteristics of dielectric gratings with rectangular and trapezoid shapes. The presented scheme is useful to study the diffraction problem of dielectric gratings with arbitrary shape and complicated configuration.