Luminescence and optical properties of Fe²⁺:ZnTe crystal grown by temperature gradient solution method

Iron-doped ZnTe (Fe²⁺:ZnTe) crystal can be used as promising gain media for mid-infrared laser. However, there are few studies in the optical properties of Fe²⁺:ZnTe crystal from mid-infrared to ultraviolet. In this work, large size Fe²⁺:ZnTe bulk crystal (the concentration of Fe ions is about 10¹⁹ cm⁻³) with a dimension of Φ30 mm × 50 mm was grown by the temperature gradient solution growth (TGSG) method. The luminescence and optical properties of Fe²⁺:ZnTe from terahertz wave to ultraviolet wave have been studied. The evaluated refractive index of Fe²⁺:ZnTe crystal is approximately 2.5–3.0 at the frequency range of 0.5–2.0 THz range. And its band gap is estimated to be about 2.24 eV. It is noted that strong absorptions at the wavelength of 2.8–4.7 μm and 705 nm were observed. Based on the experimental results, the energetic positions of Fe²⁺ center such as ³T₁, ⁵T₂, ⁵E in ZnTe crystal were proposed.