Cracking mechanism and spectral properties of Er,Yb:CaGdAlO4 crystals grown by the LHPG method

Abstract

High quality Er,Yb:CaGdAlO₄ (Er,Yb:CALGO) single crystals with a diameter around 1 mm were successfully grown and investigated for the first time by the laser heated pedestal growth (LHPG) method. The cracking mechanism of (001) planes was studied via density functional theory (DFT). The doping concentration of Er³⁺ and Yb³⁺ was calculated by X-ray fluorescence analysis (XRF). The XRD pattern confirms that the phase of Er,Yb:CALGO is consistent with pure CALGO and the crystal quality was measured through Laue back-reflection measurements. The optical properties including absorption spectra, mid-infrared fluorescence spectra and fluorescence lifetime of the Er³⁺, Yb³⁺ co-doped CALGO crystal were measured at room temperature to assess its potential for improving absorption efficiency. Further research found that the disordered structure of the CALGO crystal could achieve wider absorption and emission bands accompanied with efficient energy transfer from the excited Yb³⁺ to Er³⁺. Our results indicated that the Er,Yb:CALGO crystal is a promising material for achieving tunable mid-infrared lasers.