Cooperative downconversion and near-infrared luminescence of Tb3+/Yb3+ co-doped tellurite glass

The different concentration of Tb3+/Yb3+ co-doped tellurite glasses were prepared by high-temperature melting-quenching method. The near-infrared (NIR) luminescence of co-doped samples upon the excitation of Tb3+ ions with a green visible photon at 484 nm was investigated, and two NIR photons could be emitted by Yb3+ (2F5/2 → 2F7/2) through cooperative energy transfer from Tb3+ to two Yb3+ ions. On the other hand, the Yb3+ co-doped concentration dependence on the visible and NIR emissions, decay lifetimes and quantum efficiencies from the downconversion have been studied. The NIR quantum efficiency achieved 172% before the concentration quenching threshold.