Upconversion luminescence of Tm ³⁺ /Yb ³⁺ codoped oxyfluoride glasses

Abstract

Novel oxyfluoride glasses are developed with the composition of 30SiO2–15Al2O3–28PbF2–22CdF2–0.1TmF3–xYbF3–(4.9−x) AlF3(x=0, 0.5, 1.0, 1.5, 2.0) in mol fraction. Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm3+: 1D2→3F4, 1G4→3H6, 1G4→3F4 and 3H4→3H6, respectively, are observed. Due to the sensitization of Yb3+ ions, all the upconversion luminescence intensities are enhanced considerably with Yb3+ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.