Influence of temperature on up-conversion luminescence in Er3+/Yb3+ doubly doped lead-free fluorogermanate glasses for optical sensing.

Green and red up-conversion luminescence spectra corresponding to 2 H 11/2 , 4 S 3/2 → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions of Er 3+ ions in Er 3+ /Yb 3+ co-doped lead-free fluorogermanate glasses have been examined as a function of Yb 3+ concentration and temperature. The green-to-red luminescence intensity ratio diminishes with increasing Yb 3+ concentration. The luminescence intensity ratio for bands related to the 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ was determined and temperature sensitivity parameters were calculated. The maximal temperature sensitivities for Er 3+ /Yb 3+ co-doped glass samples increase with increasing Yb 3+ concentration and the highest value of 42.5 × 10 −4 K −1 at room temperature was obtained for 0.5Er-3Yb system. Based on gathered data it was concluded that Er 3+ /Yb 3+ co-doped lead-free fluorogermanate glasses are promising for optical temperature sensing. [ABSTRACT FROM AUTHOR]