Energy states of a Cr$^{2+}$ ion in ZnSe crystals

ZnSe:Cr single crystals fabricated by diffusion doping are studied. The optical density spectra in the energy range 0.4–3 eV are investigated. The chromium concentration in the investigated crystals is determined by the absorption-edge shift. The energy states of the Cr$^{2+}$ ion in ZnSe crystals are calculated. The nature of optical transitions determining the optical properties of ZnSe:Cr single crystals in the visible and IR spectral regions is established. It is shown that effective excitation of the IR luminescence of ZnSe:Cr crystals is implemented by light from the fundamental absorption region of Cr$^{2+}$ ions.