Abstract
An approach to the design and the realization of a broadband multilayer anti-reflection (AR) coating with high transmission is proposed in this study. A binominal multi-section transformer is employed to efficiently determine the thickness and the refractive index of each matching layer, while those layers can be further realized by doping different fractions of subwavelength-size silicon powders (for relatively-high-index layers) or air pores (for relatively-low-index layers) into the low-loss HDPE polymer host. Based on this scheme, we design a ten-layer AR coating for widely used silicon wafer. The designed AR coatings are double-sided integrated with a 375-µm-thick silicon wafer, which can enhance the overall THz transmission to higher than 95.00% from 0.250 THz to 0.919 THz (114.46% fractional bandwidth) for either T E-polarized or T M-polarized THz beam incident from an arbitrary angle below 50 .