Crystal growth, first-principle calculations, optical properties and laser performances toward a molybdate Er3+:KBaGd(MoO4)3 crystal

Abstract

A well-shaped Er3+:KBaGd(MoO4)3 (Er3+:KBGM) crystal with the size of 48 × 38 × 15 mm3 was grown by the flux method and, its structure, morphology and optical properties were studied. The first principal calculations on the band structure and density of states of the crystal were also conducted. The important spectroscopic parameters of the Er3+:KBGM crystal were calculated and analyzed by Judd-Ofelt theory. The polarized stimulated emission spectra were investigated by F-L method. The results of up-conversion spectra analysis revealed that two intense green fluorescence bands centered at 533 nm and 554 nm and a broadened weak red fluorescence band at 665 nm were observed when excited at 981 nm. According to the spectroscopic studies, as well as the analysis of decay time of the 4I13/2 state, the specific energy transfer mechanism of Er3+ ion in this crystal was elucidated. Laser experiment aiming at 1.55 μm continuous-wave laser was conducted in a plane-plane cavity and, when the optimized transmittance of output couplers was 3%, a maximum of 1.05 W laser emission was acquired with the corresponding slope efficiency of 15.36%. With the combination of all the studies, Er3+:KBGM crystal was proved to be a prominent crystal for the 1.55 μm laser.