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

Abstract Compositional dependence of spontaneous emission of Er 3+ 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 Er 3+ doped and Yb 3+ /Er 3+ 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 Er 3+ . The introduction of Na 2 B 4 O 7 shortens the radiative lifetime of the erbium pump level ( 4 I 11/2 ) as well as decreases the visible luminescence resulting from up conversion effect.