Growth, structure and spectroscopic properties of melilite Er: CaLaGa3O7 crystal for use in mid-infrared laser

Single crystals of pure and Er3+ doped CaLaGa3O7 were firstly grown by the Czochralski technology. The structure of CaLaGa3O7 was investigated. The electronic structures of CaLaGa3O7 crystal were performed by using first-principles calculations based on density functional theory (DFT) methods. Its band structure and density of states were presented. The polarized absorption, emission spectra including up-conversion, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er: CaLaGa3O7 crystal were measured at room temperature. Detailed spectroscopic analyses of Er: CaLaGa3O7 were carried out. Based on the Judd-Ofelt theory and the polarized absorption spectra, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated. The energy transfer mechanism in Er: CaLaGa3O7 crystal was also studied in this work. It concludes that Er: CaLaGa3O7 crystal can act as a promising candidate for mid-infrared lasers.