Spectroscopic properties of stoichiometric CaTbAlO4 crystal as a visible laser gain medium

Abstract

A CaTbAlO4 crystal was grown by the Czochralski method and the polarized spectroscopic properties of the crystal were investigated at room temperature. The peak absorption cross sections at 484.6 nm for σ and π polarizations are 2.97 × 10−22 and 0.68 × 10−22 cm2, respectively. Based on the Judd-Ofelt theory, the spontaneous transition probabilities, fluorescence branching ratios, and radiative lifetime of the 5D4 multiplet of Tb3+ in the crystal were obtained. For σ and π polarizations, the peak emission cross sections at 545 nm are 9.55 × 10−22 and 2.48 × 10−22 cm2, as well as the full widths at half maximum of the green fluorescence bands are about 7 and 10 nm, respectively. The fluorescence lifetime and fluorescence quantum efficiency of the 5D4 multiplet of Tb3+ are 1.84 ms and 79%, respectively. Above results indicate that the CaTbAlO4 crystal is a promising gain medium for visible laser.