UV and visible upconversion luminescence in Er³⁺:YAG under red laser excitation

This paper reports that the ultraviolet and visible upconversion luminescence from the ^4S_3 / 2, ^2G_9 / 2 and ^2P_3 / 2 levels have been observed in Er^3 + :YAG following 647.2 nm excitation of the ^4F_9 / 2 multiple. Upconversion luminescence intensity dependence on pump power was recorded. The measured decay profiles were theoretically fitted by kinetics theory and the basically good agreements were achieved. The results indicate that some energy transfer processes proposed to explain the observed upconversion phenomena are reasonable.