Optical transitions and up-conversion emission of Tm3+-singly doped and Tm3+/Yb3+-codoped oxyfluoride glasses

Novel oxyfluoride glasses SiO2–Al2O3–Na2O–ZnF2 doped with Tm3+ and Tm3+/Yb3+ 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 1D2 → 3F4 emission of Tm3+-singly doped glass were determined to be 12 μs, and 35.3%, 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.