Temporal dynamics of upconversion luminescence in Er3+, Yb3+ co-doped crystalline KY(WO4)2 thin films

Crystalline Er3+ and Yb3+ singly and doubly doped KY(WO4)2 thin films were grown by low-temperature liquid-phase epitaxy. Absorption, luminescence, excitation and temporal evolution measurements were carried out for both Er3+ and Yb3+ transitions from 10 K to room temperature. Green Er3+ upconversion luminescence was observed after Yb3+ and Er3+ excitation. The mechanisms responsible for the upconversion phenomena detected in each case were identified.