Up-conversion luminescence of Tm3+/Yb3+ 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 1 G 4 → 3 H 6 transition and the other at 667 nm due to 1 G 4 → 3 F 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 1 G 4 → 3 H 6 and 1 G 4 → 3 F 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 ( 3 H 5 + 3 H 5 → 3 H 6 + 3 F 2 ) enhanced resulting in the decrease of up-conversion luminescence intensities and leading to the concentration quenching.