Co-effects of Yb^3+ sensitization and Pr^3+ deactivation to enhance 27 μm mid-infrared emission of Er^3+ in CaLaGa_3O_7 crystal

Abstract

Er3+/Yb3+/Pr3+: CaLaGa3O7 crystal was successfully grown by the Czochralski method. Detailed spectroscopic analyses of Er3+/Pr3+: CaLaGa3O7, Er3+/Yb3+: CaLaGa3O7 and Er3+/Yb3+/Pr3+: CaLaGa3O7 crystals were carried out. Compared with Er3+/Pr3+: CaLaGa3O7 and Er3+/Yb3+: CaLaGa3O7 crystals, Er3+/Yb3+/Pr3+: CaLaGa3O7 crystal not only shows a better absorption characteristic but also exhibits weaker up-conversion and near-infrared emissions, as well as superior mid-infrared emission. Furthermore, the self-termination effect for the 2.7 μm erbium laser is suppressed successfully since the fluorescence lifetime of the 4I13/2 lower level of Er3+ decreases markedly while that of the upper 4I11/2 level falls slightly in Er3+/Yb3+/Pr3+: CaLaGa3O7 crystal. Besides, the sensitization effect of Yb3+ and deactivation effect of Pr3+ ions as well as the energy transfer mechanism in Er3+/Yb3+/Pr3+: CaLaGa3O7 crystal were studied in this work. Moreover, energy transfer microparameters between Yb3+ and Er3+ were also calculated and analyzed based on Dexter's model. In conclusion, the introduction of Yb3+ and Pr3+ is favorable for achieving an enhanced 2.7 μm emission in Er3+/Yb3+/Pr3+: CaLaGa3O7 crystal which can act as a promising candidate for mid-infrared lasers.