Up-conversion luminescence of Tm 3+/Yb 3+ co-doped oxy-fluoride glasses

Abstract

The oxy-fluorosilicate glasses co-doped with Yb 3+/Tm 3+ were prepared. The absorption spectra were recorded. The Tm 3+ ion showed two absorption bands, with one at 774 nm due to 1G 4→ 3H 6 transition and the other at 667 nm due to 1G 4→ 3F 4 transition. The energy transfer between Tm 3+ ion and Yb 3+ ion and the up-conversion fluorescence of Tm 3+ ion were investigated using 980 nm LD excitation. The results showed that the blue and red emissions were three-photon absorption processes corresponding with 1G 4→ 3H 6 and 1G 4→ 3F 4 transition, respectively. Compared with the fluorescence intensities of the different Tm 3+ doping concentration samples, 0.2 mol.% is the optimal concentration for the oxy-fluorosilicate glass. When the concentration was more than 0.2 mol.%, the cross relaxation of Tm 3+ ions ( 3H 5+ 3H 5→ 3H 6+ 3F 2) enhanced resulting in the decrease of up-conversion luminescence intensities and leading to the concentration quenching.