Binary and Ternary Optical Crystals ZnSe:Fe<sup>2+</sup> and ZnMgSe:Fe<sup>2+</sup> for Mid-IR Applications

In this study, binary ZnSe:Fe²⁺ crystals and a concentration series of ternary Zn 1-x Mg x Se:Fe²⁺ (0 < x < 0.6) were grown using the vertical Bridgman method in graphite crucibles under high argon pressure. The influence of Mg incorporation on the structural perfection, electronic energy levels, and optical absorption/emission characteristics was systematically investigated. With increasing Mg content, a monotonic redshift of both absorption and luminescence bands was observed, which is attributed to modifications in the crystal field surrounding Fe²⁺ ions and to changes in the host lattice parameters. The correlation between composition, crystal structure, and optical response was analyzed to elucidate the mechanisms of Fe²⁺-related transitions. These results demonstrate the potential of Zn 1-x Mg x Se:Fe²⁺ as tunable mid-infrared laser media and provide guidelines for the compositional engineering of A²B⁶-based laser materials.