有限口径亚波长衍射光学器件的严格矢量分析

Rigorous Vector Analysis of Finite Aperture Subwavelength Diffractive Optical Elements

利用二维时域有限差分(FDTD)方法作为严格电磁计算模式,分析、比较了连续面型和经过Farn方法得到的亚波长结构面型的衍射微柱透镜在TE极化波和TM极化波入射情况下的聚焦特性。对不同F数衍射微柱透镜的严格矢量分析表明,亚波长结构器件的聚焦特性对输入光波的极化情况有更强的敏感性。并简要讨论了FDTD方法的数值色散和计算空间吸收边界的设置等问题。

A rigorous vector analysis of diffractive optical elements (DOEs) that are finite in extent and have subwavelength structures was presented by using a two dimensional finite-difference time-domain (FDTD) method. The focusing characteristics of continuous profile lenses and subwavelength lenses (SWLs) obtained by generalizing the design approach presented by Farn, for different incidence polarization waves (TE polarization and TM polarization) and for different F-numbers of lenses were analyzed. The comparative results have shown that the focusing characteristic of SWLs is more sensitive to the polarization of incidence wave than that of continuous profile lenses. Minimizing the numerical dispersion in the FDTD calculation region and setting the absorbing boundary have been discussed also.