Temperature dependence of upconversion luminescence in erbium-doped tellurite glasses

Temperature quenching characteristics of infrared-to-visible frequency upconversion in ytterbium-sensitized erbium-doped tellurite glasses under 970 nm excitation were reported. Intense upconversion emissions around 530, 545 and 657 nm corresponding to the 2H11/2, 4S3/2 and 4F9/2 transitions to the 4I15/2 ground state were observed. The green emission around 530 nm presents continuous increase with increase of temperature. While the emission around 545 nm increases from 20 to 80 K and reaches the largest value around 80 K, then decreases from 80 to 300 K. The dependence of intensity characteristics on temperature was systematically analyzed by rate equations and a simple three-level system. In addition, the temperature dependence on the multiphonon relaxation rates (2H11/2, 4S3/2→4F9/2) fitted with 4 phonons of the 760 cm−1 was presented.