Growth, thermal and spectroscopic properties, and continuous-wave laser performance of Tm, Ho: GGAG crystal for ∼ 2 μm lasers

Abstract

In this work, crystal growth, thermal properties, spectroscopic characterization, energy-transfer (ET) schemes and continuous wave (CW) laser operation of Tm, Ho: Gd3Ga3Al2O12 (GGAG) disordered crystal were systematically studied. The thermal conductivity was calculated to be 8.53 Wm-1K−1 at 25 °C. The optical properties including absorption and emission spectra were investigated in detail. The crystal exhibits broad absorption band at 784 nm and the full width at half maximum (FWHM) and absorption coefficient are about 36 nm and 2.20 cm−1, respectively. The maximum stimulated emission cross-section for the 5I75I8 transition of Ho3+ ions at 2.07 μm is calculated to be 4.94 × 10−19 cm2 and the emission bandwidth is about 56 nm. Continuous wave laser performance of a 〈111〉 oriented Tm, Ho: GGAG crystal sample was demonstrated, and a maximum output power of 218 mW was achieved at 2112 nm. The results indicate that the Tm, Ho: GGAG crystal is promising for broadly tunable, ultrashort pulse lasers at ∼ 2 μm.