1.48 μm emission properties and the cross-relaxation mechanism in chalcohalide glass doped with Tm3+

Abstract 1.48 μm emission properties and the cross-relaxation mechanism of Tm3+ ions in 0.7(Ge0.25As0.10S0.65) + 0.15GaS3/2 + 0.15CsBr glass were investigated. Both the relative intensity ratio of the 1.48 μm emission to 1.82 μm and the measured lifetime of the 3H4 level decreased with increasing Tm3+ concentration. When temperature decreased from room temperature to 20 K, lifetimes of the 3H4 level increased from 670 to 970 μs. At the same time, the critical distance for cross-relaxation decreased from 1.11 to 0.93 nm. These results indicate that cross-relaxation (3H4, 3H6 → 3F4, 3F4) became less effective as temperature decreased. Analysis of the temperature dependence of cross-relaxation rates showed that cross-relaxation in Tm3+ is a phonon-assisted energy transfer process. The major phonon contributing to the process is from the Ga–Br vibration in [GaS3/2Br]− units.