Growth, structure and spectroscopic properties of Er:YSr3(PO4)3 disordered crystal for mid-infrared laser applications

Mid-infrared lasers in the ⁓ 3 µm region activated by Er ³⁺ ion has attracted considerable attention due to their important applications. Herein, a heavy concentration (30 mol%) Er ³⁺ ion doped YSr ₃(PO ₄) ₃ (Er:YSP) single crystal with a high crystalline quality was grown through the Czochralski pulling method. The structure of single crystal was ascertained to be cubic system with the point group 4 ¯ 3 m using the powder X−ray diffraction and Rietveld structural refinement methods. Furthermore, the band structure and density of states of the crystal were analyzed by the first principal calculations. The absorption and fluorescence spectra were also investigated. An intense absorption band located at 974 nm with a full width half-maximum of 18 nm, where the absorption cross section was obtained to be 3.72 × 10 ⁻²¹ cm ² . The full width half-maximum value of emission band centered at about 3090 nm is up to be 140 nm, which is very suitable for realizing ultrashort pulses and tunable lasers. In addition, the fluorescence lifetime of the upper ⁴I _11/2 and lower ⁴I _13/2 levels were obtained to be 0.65 ms and 5.37 ms, respectively. All the results show that the disordered structure crystal Er:YSP could potentially serve as a laser medium for the ⁓ 3µm region.