Abstract
Photoluminescence properties of Er3+-doped 70TeO(2)-30ZnO glasses are investigated. Infrared to visible upconversion has been observed at room temperature in this tellurite glass using a 797 nm excitation laser. A study of the S-4(3/2) --> I-4(15/2) and F-4(9/2) --> I-4(15/2) transitions versus excitation laser power shows evidence for a two-step upconversion process under this excitation. The red emission originating from the F-4(9/2) --> I-4(15/2) transition is enhanced relative to the green emission with increasing Er3+ ion concentration. This behaviour has been explained as being due to an energy transfer between activator ions. The temperature dependence of the upconversion intensity has also been studied in the range 60-310 K, It was found that the red emission of F-4(9/2) --> I-4(15/2) grows considerably relative to the green transition with increasing temperature in heavily doped samples. This indicates that energy transfer mechanisms, responsible for the red emission enhancement, are temperature dependent.