Antireflective characteristics of Ge1-xCx films on sub-wavelength structured ZnS surfaces

Antireflective sub-wavelength structures (SWSs) combined a Ge1-xCx coating on Zinc sulfide (ZnS) can enhance the long-wave infrared transmission and durability of ZnS, which have the potent for practical applications. We have investigated the antireflective characteristics of Ge1-xCx sub-wavelength periodic hole structures on ZnS through the Fourier modal method (FMM) for application with normally incident, randomly polarized, 10.6 mu m wavelength. Then according to the results, we have successfully fabricated the sub-wavelength periodic square hole structures with Ge0.05C0.95 films on one side of ZnS. A substantial transmittance improvement for bare ZnS in the 8-12 mu m spectral region was obtained. (C) 2011 Elsevier B.V. All rights reserved.