Design and Optimization of Polarization-Insensitive Broadband Antireflection Coating for MWIR Windows Using ZEMAX

Abstract

This study designed and simulated polarization-insensitive broadband anti-reflection coatings (BBARCs) for a middle infrared wavelength (MWIR) window lying between 3 and 5μm, adopting ZEMAX software. BaF2, MgF2, ZrO2, SiO, SiO2, CdTe, Si, and Y2O3 were selected as transparent materials deposited on germanium (Ge), silicon (Si), and zinc selenide (ZnSe). Results show that the reflectance of Ge, Si, and ZnSe substrates reduced from (36%, 30%, and 16%) to virtual null reflectance over a wide angular range. ZEMAX software was used to reduce reflectance considerably and improve spectral performance. In this work, the optimum design was achieved with layers systematically added to the substrate and only layer thickness varied, keeping the index of refraction fixed.