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

1.48 mum emission properties and the cross-relaxation mechanism of Tm3+ ions in 0.7(Ge0.25As0.10S0.65) + 0.15GaS(3/2) + 0.15CsBr glass were investigated. Both the relative intensity ratio of the 1.48 pin emission to 1.82 mum and the measured lifetime of the H-3(4) level decreased with increasing Tm3+ concentration. When temperature decreased from room temperature to 20 K, lifetimes of the H-3(4) level increased from 670 to 970 mus. At the same time, the critical distance for cross-relaxation decreased from 1.11 to 0.93 nm. These results indicate that cross-relaxation (H-3(4), H-3(6) --> F-3(4), F-3(4)) 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. (C) 2003 Elsevier Science B.V. All rights reserved.