Antireflection coating on GaAs for the range 8-12 μm

Abstract

The antireflection coating design on GaAs for the spectral range from 8im to 12,im is discussed. Based on the comprehensive search technique the best systems of up to 5 layers of ZnS and Ge are presented.To get better antireflection effect the materials with lower refractive indices are needed. Utilization of yttria for this purpose is suggested and optical constants in JR for both evaporated and sputtered layers are established.Though evaporated yttria layers exhibit relatively high absorption in the region of our interest, sputtered films are much better and several systems of up to four layers of Y203, ZnS and Ge are computed by the comprehensive search technique again.