Energy back transfer, migration and energy transfer (Yb-to-Er and Er-to-Yb) processes in Yb,Er:YAG

A comparison and discussion of the energy back transfer, migration of energy and direct energy transfer process, from Yb-to-Er and Er-to-Yb ions, in the luminescent system Yb, Er: YAG are presented. The sample crystal was excited with a tunable optical parametric oscillator system. The Yb ions as donors were excited at 940 nm and its fluorescence decay measured at 1030 nm. On the other hand, the Er ions as donors were excited at 800 and 670 nm, and the fluorescence decay of Yb ions as acceptors measured at 1030 nm. The analysis is done through the solution to the General Energy Transfer Master Equations. The ytterbium fluorescence decays in both cases were fitted and found that the migration of the energy among Yb ions is neglected when they act as acceptors.