Energy transfer mechanisms in Er-Yb-Y disilicate thin films

We investigate the optical properties of Er-Yb-Y disilicate thin films in which Er and Yb contents are varied independently. From time-resolved measurements of Yb decay in absence and in presence of Er, we analyzed and modeled the energy transfer mechanism identifying all the de-excitation channels and measuring a coupling constant CYb-Er = 3.0 x 10(-39) cm(6)/s. Finally, we calculated the efficiency of Yb-Er energy transfer process and we correlated it with Er photoluminescence, demonstrating that it is controlled by the energy transfer mechanism. The maximum efficiency is found for 1.5 x 10(21) Er/cm(3) and 1.5 x 10(22) Yb/cm(3), by making this material very promising for optical amplifiers.