Partition, luminescence and energy transfer of Er3+/Yb3+ ions in oxyfluoride glass ceramic containing CaF2 nano-crystals

A complete spectroscopic investigation of energy transfer processes in oxyfluoride glass ceramics containing CaF2 nano-crystals doped with various amounts of Er3+ and Yb3+ was reported. An enhancement of the 1.53 μm emission and infrared to visible up-conversion fluorescence was confirmed experimentally due to efficient non-radiative energy transfer from Yb3+ to Er3+ ions concentrated in CaF2 nano-crystals. The efficiency of Yb3+ to Er3+ energy transfer in excess of 85% was obtained for 0.5 mol% Er3+/2.0 mol% Yb3+ co-doped glass ceramic. Using rate equation formulism, the coefficient of Yb3+ to Er3+ energy transfer was determined to be about 3.5 times higher than that of Er3+ to Yb3+ energy back transfer, which is sufficient to provide high 4I11/2 population of Er3+ to improve the fluorescence of the co-doped glass ceramics.