Abstract: Tellurite glasses 75TeO₂-20ZnO-(4.6-x)La₂O₃-0.4Er₂O_3-xYb₂O₃ (x=0, 0.4, 0.8, 2.0, 3.2, 4.0) were prepared by conventional melt-quenching method. The effects of temperature (8-300K) and the ytterbium concentration on upconversion characteristics were investigated. When the Yb³⁺ concentration is 2mol%, the upconversion emission intensities around 545nm and 657nm present 6-fold and 4-fold enhancement, respectively, compared with Er³⁺-doped glass at room temperature. The green emission intensities around 530nm present monotonic increase with increasing temperature from 8K to 300K. The green emission intensities around 545nm increase with increasing temperature from 8K to 80K and reach the maximum at around 80K, then decrease with increasing temperature from 80K to 300K. The characteristics of the red emission intensity around 657nm are similar to the green emission intensity around 545nm. The effects of temperature and concentration of ytterbium on upconversion characteristics are analyzed by rate equations in details, which match well with the experiment results.

Key words: tellurite glasses, upconversion, rate equation