Er3+/Yb3+ co-doped TeO2-ZnO-ZnF2-La2O3 glass with a high fluorescence intensity ratio for an all-fiber temperature sensor

Er3+/Yb3+ co-doped TeO2-ZnO-ZnF2-La2O3 (TZZL) glasses with different concentrations of Er 3+ ions were fabricated. Strong green upconversion emission bands centered at 523 and 545 nm induced by 980 nm excitation were observed. The maximum emission intensity of the TZZL glasses was obtained at the Er(3+)ion concentration of 0.2 mol%. High-temperature difference (Delta T = 131.8 degrees C) between the transition and onset crystallization temperatures was confirmed by differential thermal analysis curve. The relationship between fluorescence intensity ratio value and temperature was examined within 303-560 K. The maximum absolute sensitivity (S-a) and the maximum relative sensitivity (S-r) was 0.006 K-1 at 560 K and 0.012 K-1 at 303 K, respectively. A prototype of an all-fiber temperature sensor was designed, and its temperature-sensing performance within 293-383 K was evaluated. Results showed that the absolute errors were within +/- 1 K, and the largest value of relative standard deviation was approximately 0.2%, suggesting that Er3+/Yb3+ co-doped TZZL glasses have potential applications in optical-fiber temperature sensors.