Influence of temperature on up-conversion luminescence in Er~(3+)/Yb~(3+) doubly doped lead-free fluorogermanate glasses for optical sensing

摘要

Green and red up-conversion luminescence spectra corresponding to ~2H_(11/2),~4S_(3/2) → ~4I_(15/2) and ~4F_(9/2) → ~4I_(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 ~2H_(11/2) → ~4I_(15/2) and ~4S_(3/2) → ~4I_(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.