Energy transfer and 1.3 μm emission in Pr–Yb codoped tellurite glasses

To seek the possibility of an efficient 1.3 μm amplifier in oxide materials, the concentration and temperature dependence of fluorescence properties of the Pr3+ : 1G4 → 3H5 at 1.3 μm and Yb3+:2F5/2 → 2F7/2 at 1 μm were investigated in codoped tellurite glasses with compositions of 75TeO2–20ZnO–5Na2O–xPr2O3–yYb2O3. By 0.97 μm pumping, the 1.3 μm emission of Pr3+ was sensitized by the Yb → Pr energy transfer. The lifetime obtained by 1.02 μm emission of Yb3+ at room temperature was concentration quenched with the presence of only 0.1 mol% Pr2O3. The energy transfer efficiency from Yb to Pr in a codoped glass was found to be more than 90% even in the glass of [Yb]/[Pr]>100. With increasing temperature, the Yb-lifetime in singly doped glass increased and that in codoped glass decreased. These results can be explained by assuming rapid energy migration between Yb ions and promotion of Yb3+ : 2F5/2 → Pr3+: 1G4 transfer at higher temperature.