Increasing of the population feeding of the 4I13/2 Er3+ level by Ce3+ codoping in TeO2-WO3-Na2O glasses

Er3+ doped tellurite glasses, by virtue of a high stimulated emission cross section and a broad emission bandwidth at 1.5 ?m, have been recognized as one of the most promising materials for broadband Er3+ doped fiber amplifier (EDFA). High optical quality TeO2-WO3-Na2O glasses doped with Er3+ and codoped with Ce3+ were prepared and characterized using Raman, absorption and luminescence spectroscopies. Raman spectra show that the host glass is constituted of interconnected chains of bipyramidal TeO4, octahedral WO6 and tetrahedral WO4. Absorption and luminescence spectra show that these doped glasses present large stimulated cross-sections and absorption cross-sections around 1.5 ?m, which are typical of tellurite glasses. The incorporation of sodium oxide not only leads to the stabilization of the glassy structure, but also makes it possible to perform ion exchange in order to obtain optical waveguides. The lifetime measurements show that tungsten-tellurite glasses have an increased multiphonon decay rate of the 4I11/2 level with respect to zinc-tellurite glasses. Moreover, while not affecting the 4I13/2 lifetime, the Ce3+-codoping is also highly effective in reducing the 4I11/2 lifetime through phonon-assisted energy transfer. This result demonstrates that Er3+ / Ce3+ codoping in tungsten-tellurite glasses is effective in increasing the population of the 4I13/2 level of erbium ions upon excitation at 980 nm.