Optical losses in polycrystalline CVD ZnS

Abstract

We discuss the reasons for the limited visible and near-IR transmittance of polycrystalline zinc sulfide produced by chemical vapor deposition (CVD). Comparison of measured scattering indicatrices, depolarization ratios, and transmission spectra in the range 0.4–4 m with theoretical predictions leads us to conclude that a significant contribution to optical losses in CVD ZnS comes from light scattering by faceted submicron inclusions with a refractive index of 1 (pores). Assuming that these defects play a key role in determining the optical loss in the material, we have estimated the pore concentration and pore size distribution in CVD ZnS before and after hot isostatic pressing.