Upconversion luminescence in Tm3+/Yb3+co-doped lead tungstate tellurite glasses

Abstract This work reports the upconversion luminescence properties of Tm 3+ /Yb 3+ ions in lead tungstate tellurite (LTT) glasses. Judd–Oflet intensity parameters have been obtained from the absorption band intensities of Tm 3+ singly-doped and Tm 3+ /Yb 3+ co-doped LTT glasses. The spontaneous emission probabilities, radiative lifetimes and branching ratios for 1 G 4 and 3 H 4 emission levels of Tm 3+ have been determined. Upconversion luminescence has been observed by exciting the samples at 980 nm (Yb 3+ : 2 F 7/2 → 2 F 5/2 ) at room temperature. Four upconversion emission bands corresponding to the 1 G 4 → 3 H 6 (477 nm), 1 G 4 → 3 F 4 (651 nm), 1 G 4 → 3 H 5 (702 nm) and 3 H 4 → 3 H 6 (810 nm) transitions have been identified. The relative variation in the intensities of upconversion bands, the different channels responsible for upconversion spectra and the effect of Yb 3+ ions concentration on the upconversion luminescence of Tm 3+ ions have also been discussed.