Visible and mid-infrared spectral performances of Dy3+: CaF2 and Dy3+/ Y3+: CaF2 crystals

Abstract 1 at% Dy3+: CaF2 and 1 at% Dy3+/5 at% Y3+: CaF2 crystals were grown by Bridgman method. Absorptions, visible and mid-infrared emissions, and fluorescence decay curves were measured. By applying Judd-Ofelt (J-O) theory, for Dy3+/Y3+: CaF2 crystal stronger oscillator strength and radiation transition probability were derived. The effect of Y3+ ions incorporation into CaF2 crystals on the light emission of Dy3+ ions was discussed. Co-doped Y3+ ions can destroy Dy clusters, cripple the concentration quenching effect, and enhance the yellow and mid-infrared fluorescence intensity. The yellow fluorescence intensity of Dy3+/Y3+: CaF2 is ~ 70 times higher than that of Dy3+: CaF2 crystal. The local structure of Dy3+ ions was analyzed, and co-doping Y3+ can increase the quantity of tetragonal Dy clusters. In Dy3+/Y3+: CaF2 crystal, the tetragonal Dy clusters occupy the dominant position, and the fluorescence lifetime (τf) is relatively short. It can be concluded that Dy3+: CaF2 and Dy3+/Y3+: CaF2 crystals are expected to achieve yellow and mid-infrared laser output simultaneously.