Optical transitions and up-conversion emission of Tm~(3+)-singly doped and Tm~(3+)/Yb~(3+)-codoped oxyfluoride glasses

摘要

Novel oxyfluoride glasses SiO_2-Al_2O_3-Na_2O-ZnF_2 doped with Tm~(3+) and Tm~(3+)/Yb~(3+) were fabricated. The optical properties of the synthesized glasses were experimentally and theoretically investigated in detail. According to the Judd-Ofelt theory, the Judd-Ofelt intensity parameters were calculated. With these intensity parameters, the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes were obtained. The fluorescence lifetime and quantum efficiency for ~1D_2 -- > ~3F_4 emission of Tm~(3+)-singly doped glass were determined to be 12 mu s, and 35.3 percent, respectively. The up-conversion luminescence was observed upon excitation with 980 nm diode laser. The dependence of the up-conversion emission intensity upon the excitation power was examined, and the up-conversion mechanisms were discussed.