Some key factors affecting energy up-conversion efficiency of rare-earth doped oxy-fluoride materials

In this study, Er3+–Yb3+ co-doped oxy-fluoride glasses based on TeO2 have been investigated. Some approaches to enhancing up-conversion efficiency are presented. Generally, hosts with low phonon energy are beneficial to energy up-conversion. It is found that when the quasi-field-strength parameter \overlineM of the host is adjusted to approach that of the rare-earth dopant, the materials show high up-conversion efficiency. Selecting a suitable excitation photon energy to match the level of activated ions and/or sensitizing ions is a necessary condition for realizing high up-conversion efficiency. Our results offer some practical references for preparing rare-earth-doped energy up-conversion materials.