Thermal and spectroscopic properties of Er3+-doped fluorotellurite glasses modified with TiO2 and BaO

We have investigated the thermal and spectroscopic properties of Er3+-doped fluorotellurite glass with the basic molar composition 75%TeO2-10%P2O5-10%ZnO-5%PbF2 and the glasses modified by substituting 5%TeO2 by a metal oxide, namely TiO2 or BaO. As follows from the thermal studies, the glass containing TiO2 as a modifier exhibits a higher stability against crystallization with respect to two other glasses. The ellipsometric data have provided a Sellmeier-type dispersion relation of the refractive index of the investigated glasses. The absorption and fluorescence spectra, along with the photoluminescence decay of the I-4(13/2) levels of the Er3+ ion, have been analyzed within the Judd-Ofelt and Fuchtbauer-Ladenburg approaches. It appears that the quantum efficiency of the I-4(13/2) -> I-4(15/2) transition is quite high (above 70%), being the highest (97%) for the glass containing TiO2 as a modifier. The absorption and emission cross-section results for the I-4(15/2) <-> I-4(13/2) transition show that the glass containing TiO2 is characterized by the largest figure of merit (FOM) for the amplifier gain and indicate this matrix as a promising new host for doping with rare-earth ions.