State-selective energy transfer from Er3+ to Eu3+ in Bi2O3-GeO2-Ga2O3-Na2O glasses

The Eu3+ ion was introduced into Er3+ doped Bi2O3-GeO2-Ga2O3-Na2O (BGGN) glasses to improve the 1.5 mu m band emission. As a function of Eu2O3 doped content, we observed the increase in non-radiative decay rate of Er3+ not only I-4(11/2) energy level but also 4I(13/2) energy level, while the lifetime of Er3+:I-4(11/2) and I-4(13/2) levels were shortened from 607 to 241 mu s and from 3.37 to 1.88 ms, respectively. Accordingly, the upconversion fluorescence (green and red) was quenched. The total quantum efficiency of the Er3+:I-4(13/2) increased with the Eu2O3 content increasing up to 0.2 mol% due to the state-selective energy transfer from Er3+ to Eu3+. (C) 2008 Elsevier B.V. All rights reserved.