Effect of the introduction of Na2B4O7 on erbium luminescence in tellurite glasses

Compositional dependence of spontaneous emission of Er3+ was studied in borate tellurite glasses. The improvement of the luminescence at 1533 nm while pumping at 980 nm by introducing sodium tetraborate in a tellurite glass host is discussed in Er3+ doped and Yb3+/Er3+ co-doped glasses. From the absorption, emission spectra and lifetime measurements, an optimized sodium tetraborate molar concentration between 1.25% and 2.5% was shown to induce a maximum intensity of the 1533 nm spontaneous emission in correlation with a more efficient non-radiative transfer from the pump level to the emitting level of Er3+. The introduction of Na2B4O7 shortens the radiative lifetime of the erbium pump level (4I11/2) as well as decreases the visible luminescence resulting from up conversion effect.