Growth, spectral and laser properties of a Yb-doped strontium yttrium phosphate crystal with a disordered structure

Abstract

Disordered crystals have garnered increasing attention as new laser materials because of their broad emission bandwidths. This paper reports a novel Yb-doped strontium yttrium phosphate (Yb:YSr₃(PO₄)₃) crystal with a disordered structure, as well as its crystal growth, structure, spectral properties, and laser performance. The crystal structure (cubic, 3m point group) was refined using the Rietveld method. The absorption cross-section and fluorescence lifetime were determined to be 1.31 × 10⁻²⁰ cm² at 976 nm and 1267 μs, respectively. The stimulated emission cross-section was 1.04 × 10⁻²⁰ cm² at 1013 nm, with an emission bandwidth of 55 nm. In addition, continuous-wave laser operation was realized using the Yb:YSr₃(PO₄)₃ crystal with different output coupler transmissions, where the obtained maximum output power and slope efficiency were 1.3 W and 61%, respectively. A dual-wavelength regime with wavelengths centered at 1039 nm and 1047 nm (Δν = 2.2 THz) was achieved under certain conditions; thus, this crystal is expected to be employed for developing terahertz sources. In addition, the laser can operate at multiple wavelengths, ranging from 1023 to 1050 nm. The results indicate that the Yb:YSr₃(PO₄)₃ crystal with a disordered structure may be a promising multi-wavelength laser crystal.