Thermal and spectroscopic characteristics of disordered melilite Nd:BaLaGa3O7 crystal

Abstract

A disordered Nd:BaLaGa₃O₇ laser crystal was successfully grown by the Czochralski method. The effective segregation coefficient of Nd³⁺ in BaLaGa₃O₇ crystals was measured to be 1.12. A series of thermal properties, including specific heat, average linear thermal expansion coefficient, thermal diffusivity and thermal conductivity, were systematically determined as a function of temperature. The thermal conductivity increased with increasing temperature. The polarized absorption and emission spectra were measured at room temperature. Nd:BaLaGa₃O₇ possessed a large absorption bandwidth of 18 nm at 808 nm and an emission bandwidth of 32 nm at 1060 nm. According to the Judd–Ofelt theory, the spontaneous transition probabilities, the fluorescence branching ratios, and the radiation lifetime were calculated. The stimulated emission cross section for the⁴F_3/2 → ⁴I_11/2 transition was calculated to be 4.24 × 10⁻²⁰ cm². Thermal and optical properties have shown that Nd:BaLaGa₃O₇ crystals are potential alternative gain media for ultrafast lasers.