基于针法的平板偏振膜设计

Thin-Film Polarizers Designed by the Needle Method

利用针(needle)法优化技术,分别以两种不同厚度的高折射率单层膜为初始膜系,设计得到了平板偏振膜。当入射角为56°时,在中心波长1053 nm附近不小于20 nm的带宽范围内,偏振膜的p光反射率Rp<2%,s光反射率Rs>99.5%,且消光比(Tp/Ts)>200。角度特性分析结果表明,在入射角由53°增大至59°的过程中,两偏振膜的光学性能均满足设计要求,但偏振带却向短波长方向发生了移动,且带宽增大。根据蒙特卡罗容差分析,在各膜层膜厚误差独立的监控方式下,要保证成品率高于90%,则两偏振膜的最大容许膜厚标准偏差分别为1.20%和1.35%。

Thin-film polarizers were designed by the needle optimization technique. Two single high-index-layer coatings with the difference in layer thickness were used as the starting designs. At 56° incident angle,the spectral bandwidths of the polarizers are determined by the polarization region not less than 20 nm near 1053 nm,where the reflectance of p polarization is less than 2% and the reflectance of s polarization is greater than 99.5%,and the extinction ratio（Tp/Ts）is larger than 200. With the incident angle increasing from 53° to 59°,the spectral characteristics of the two polarizers meet the design requirements although the polarization regions are enlarged and hypsochromically shifted. The tolerances of the thicknesses of the layers uncorrelated are analyzed by the Monte Carlo analysis. To ensure the manufacturing yields higher than 90%,the standard deviations of random thickness for the two designs do not exceed 1.20% and 1.35%,respectively.