High performance ZnS antireflection sub-wavelength structures with HfO₂ protective film for infrared optical windows

Antireflection sub-wavelength structures (SWSs) on ZnS were designed and ZnS SWSs with HfO₂ protective film were prepared, and their properties in long-wave infrared applications were examined and compared to AR coatings. The SWS has good antireflection performance and exhibits less polarization sensitivity than the AR coating. At temperatures above 500 °C, the SWS with HfO₂ protective film has a better thermal endurance property than the multilayer AR coating. Moreover, the HfO₂ protective film significantly improved the mechanical properties of the ZnS SWS and was similar to HfO₂ covered AR coating when the HfO₂ film was not broken. This study shows that the ZnS SWS with HfO₂ protective film has promising application prospects in infrared optical windows.