Energy transfer mechanism in Yb3+:Er3+-ZBLAN: macro- and micro-parameters

Dynamics of forward energy transfer and backward energy transfer processes in fluorozirconate glass doubly doped with Yb3+ and Er3+ have been explained by 'rate equation' and 'fluorescence transfer function' models. From the rate equation analysis, macroscopic energy transfer parameters, the cross-relaxation coefficients, were determined to be 1.36x10-17 and 3.38x10-17 s-1 cm3 for the forward energy transfer (Yb3+→Er3+) and the backward transfer (Er3+→Yb3+), respectively. Based on the fluorescence 'transfer-function' model, the kinetics of the energy transfer processes between Yb3+ and Er3+ ions has been analyzed, and the microscopic energy transfer parameters of the Yb:Er-codoped system, the critical radii, were derived as 13.0 and 18.0 A for the donor-acceptor (Yb3+→Er3+) and the acceptor-donor (Er3+→Yb3+), respectively. The 1.55 μm band emission property of the rare-earth-codoped fluoride glass systems has been discussed