Spectroscopic characterization and temperature-dependent upconversion behavior of Er3+ and Yb3+ co-doped zinc phosphate glass

The zinc phosphate glass co-doped with Er3+ and Yb3+ ions was prepared by melt-quenching method. The Judd-Ofelt theory has been applied to analyze the absorption spectrum and estimate the spectroscopic parameters of Er3+ ions. Upconversion luminescence of the glass was investigated under the excitation at 976 nm. The red and green emissions of Er3+ ions were observed. The energy transfer processes between Yb3+ and Er3+ ions responsible for the upconversion emissions were discussed based on their dependences on pump power. The fluorescence decays of the relevant energy levels were measured for evaluating the energy transfer efficiency. Furthermore, the influence of temperature on upconversion emission in this glass was carried out at temperatures from 323 to 573 K. The result indicates that the glass has a potential application in the construction of optical temperature sensors based on the self-referenced FIR technique.