Optical Constants of Zinc Selenide in Visible and Infrared Spectral Ranges

Transmittance spe ctrum of ZnSe in the infrared and visible wavelength range at normal incidence was investigated by an IRTracer-100 spectrometer and a TU-19 Double-Beam Visible spectrophotometer, and the optical constants of ZnSe were obtained based on modelling transmittances of two ZnSe slabs. The results show that the transmittance values of the ZnSe slabs are higher than 0.7 in the wavelength range of 2.5–15 μm; however they decrease dramatically when the wavelength is larger than 15 μm. The refractive index of ZnSe varies within 2.6–2.8 in the wavelength range of 0.55–0.85 μm and 2.2–2.4 in the wavelength range of 2.5–20 μm. The extinction coeffi cient of ZnSe varies within 10–8–10–6 in the wavelength range of 0.55–0.85 μm and 10–5–10–4 in the wavelength range of 2.5–20 μm.