Excited energy migration and fluorescence decay in Yb-doped and Yb/Pr-codoped tellurite glasses

Concentration and temperature dependences of lifetime of Yb3+ : F-2(5/2) level were investigated in tellurite glasses doped with up to 6 mol% Yb2O3. The lifetime obtained by 1.02 mu m emission from the Yb3+ ions at room temperature was insensitive to the Yb2O3 concentration in singly doped glasses. However, the Yb-lifetime showed strong concentration quenching 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. The Yb-lifetime in singly doped glass increased and that in codoped glass decreased with increasing temperature. These results can be explained by assuming rapid energy migration between Yb ions and promotion of Yb3+: F-2(5/2) --> Pr3+ : (1)G(4) transfer at higher temperature. (C) 1999 Elsevier Science B.V. All rights reserved.