Effect of Temperature on Upconversion Luminescence in Yb~(3+)/Tb~(3+) Co-Doped Germanate Glass

摘要

In the article effect of temperature on the cooperative energy transfer in germanate glass co-doped with Yb~(3+)/Tb~(3+) under 976 nm laser diode pumping was investigated. The optimization of Tb~(3+) concentration on the upconversion luminescence was determined. Strong luminescence at 489, 543, 586, 621 nm corresponding to ~5D_4 → ~7F_J (J = 6, 4, 3) transitions and luminescence at 381, 415, 435 nm resulting from ~5D_3, ~5G+6→~ 7F_J (J = 6, 5, 4) transitions were presented. The highest upconversion emission intensity was obtained in glass co-doped with 0.7 Yb_2O_3/0.7 Tb_2O_3 (mol%). The effect of temperature on the luminescent properties of germanate glass in the range of 5-250 ℃ indicates the presence of competing phenomena: an increase in the effective absorption cross--section of Yb~(3+) ions donor as a function of temperature and migration of energy between pairs of ions Yb~(3+)-Yb~(3+) and of multiphonon excitation levels ~7F_J.