Up-conversion luminescence and temperature sensing characteristics of Er3+/Yb3+co-doped phosphate glasses

Er3+/Yb3+ co-doped phosphate glasses have been successfully prepared via tradition melt quenching technique, and the optical, luminescent and temperature sensing characteristics have been characterized by transmission spectra, photoluminescence spectra, fluorescence decay and energy level diagram. Under 980 nm laser excitation, three luminescent bands are observed at 522, 546, and 658 nm, which corresponded to H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions. The most intense red emission is found at 658 nm. Furthermore, the temperature dependent fluorescence intensity ratio (FIR) of thermally coupled emitting states (S-4(3/2), H-2(11/2)) in Yb3+/Er3+ co-doped glasses is studied under 980 nm laser excitation. A high relative temperature sensitivity of 1.22% K-1 is obtained at 303 K and the corresponding effective energy difference (Delta E) is 789 cm(-1). And the maximal temperature sensitivity at 553 K is evaluated to be 4.94 x 10(-3) K-1. All the results suggest that the Yb3+/Er3+ co-doped phosphate glasses are an efficient up-conversion material with potential application in optical thermometry.