Growth, thermal, spectroscopy and mid-infrared laser performance of an Er:LuGSGG mixed crystal

Abstract

We demonstrate the structural, thermal, spectroscopic and laser performance of a novel Er³⁺-doped LuGSGG mixed crystal grown using the Cz method. The crystal possesses a garnet structure with a lattice parameter of 12.51 Å. The thermal conductivity is 4.3 W m⁻¹ K⁻¹ and the thermal expansion coefficient is 8.5 × 10⁻⁶ K⁻¹. The spectral analysis identifies a prominent absorption peak centered at 966 nm with an absorption coefficient of 4.7 cm⁻¹, corresponding to an absorption cross-section of 1.3 × 10⁻²¹ cm² and a full width at half maximum (FWHM) of 21 nm. The absorption and fluorescence spectra of Er:LuGSGG are broadened slightly. The level lifetimes are 1.19 ms for ⁴I_11/2 and 5.06 ms for ⁴I_13/2. Under 973 nm LD end-pumping, a continuous-wave laser power of 396 mW with a slope efficiency of 10% at 2.79 μm is achieved, yielding a high beam quality with M_x²/M_y² = 1.38/1.42. The laser spectrum reveals a narrow linewidth at 2795.6 nm with an FWHM of 0.097 nm. These findings confirm significant potential of Er:LuGSGG as a gain medium for solid-state tunable and short pulse laser applications.