Energy transfer mechanisms have been quantitatively studied in Er3+/Ho3+ codoped tellurite and bismuth glass. Upon an excitation of 980 nm, an enhanced Er3+:2.7 μm emission was observed when Ho3+ was added to tellurite glass. Using Dexter’s theory, it is clearly shown that the efficiency of Er3+:4I13/2 → Ho3+:5I7 energy transfer is higher in tellurite glass than in bismuth glass. Based on upconversion and near-infrared spectra, the cross relaxation Er3+:4I13/2 + Ho3+:5I6 → Er3+:4I15/2 + Ho3+:5F5 is comparatively effective in tellurite glass, where it depletes the population of Er3+:4I13/2 level. The excellent spectroscopic characteristics indicate Er3+/Ho3+ co-doped tellurite glass has potential application for mid-infrared laser.
