Upconversion and near infrared emission in Yb–Tm mediated by ZnTe crystals in oxide glasses

This work presents a detailed investigation of the blue and near infrared (NIR) emission of Tm3+ and Yb3+ ions in ZnTe doped oxide glasses. Absorption, luminescence and lifetime measurements were performed in order to optimize the luminescent properties of Yb3+ and Tm3+. The influence of ZnTe and Yb3+ concentration on the enhancement and quenching of the emissions at 470 nm and 980 nm were determined. It was observed that the Yb3+ luminescence increases by a factor of 10, while the Tm3+ blue emission at 470 nm is quenched for both the presence of Yb3+ and ZnTe. The enhancement in the Yb3+ emission is attributed to the presence of ZnTe. Moreover, it is demonstrated that the glass can be pumped with additional wavelengths (325 nm and 532 nm) due to the absorption from the ZnTe semiconductor, allowing alternative pumping schemes. Calculations of the energy transfer microparameters from Yb3+-Yb3+ and Yb3+-Tm3+ were also performed, evaluating the influence of ZnTe in the process.