High-Performance LWIR Antireflective Films Fabrication on Ge Substrate Using LaF3 as Low Refractive Index Material

Abstract

：To improve the resistance of long wave infrared (LWIR) band antireflective films on Ge in harsh environments, film design and fabrication technology have been discussed using LaF 3 as a low refractive index material. We fabricated high-performance multilayer antireflection (AR) coatings in an LWIR band (8-12 m) via an optimized film structure and sectional preparation of LaF 3 layer on Ge substrate. The peak transmittance was 98.3%, and the average transmittance increased from 48.4% to 96.2% when double-sided coating was used. This LWIR AR coating with LaF 3 passed various environmental, durability, and mechanical properties tests while maintaining good optical properties. Key words：LaF 3 ，long wave infrared band，high performance antireflective film