Comparison of the optical properties of diffusion-doped polycrystalline Cr:ZnSe and Cr:CdTe windows

Results of the material preparation and infrared (IR) optical properties of polycrystalline Cr:ZnSe and Cr:CdTe windows are reported. Cr doping of commercial ZnSe and CdTe windows was achieved through a thermal diffusion process employing CrSe powder as the dopant source. All samples exhibited the characteristic spectral features of Cr2+-doped II–VI materials with strong IR absorption bands between 1700 and 1900 nm and broad emission spectra from 2000 to 3400 nm. The IR optical properties of Cr:CdTe were shifted by ∼150–200 nm to longer wavelengths compared to Cr:ZnSe due to the difference in crystal-field strength experienced by Cr2+ ions. The room-temperature decay times were measured to be 5–6 μs for Cr:ZnSe and 3–4 μs for Cr:CdTe. The emission lifetime of Cr2+ ions decreased by a factor of two for Cr concentrations of ∼2.6×1019 cm−3 for Cr:ZnSe and ∼0.7×1019 cm−3 for Cr:CdTe.