A NONLINEAR-ANALYSIS OF ENERGY-TRANSFER IN HIGHLY TB-3+-DOPED GLASSES

We present a comprehensive model for the resonant energy transfer of an electronic excitation between energy donors and energy acceptors. The model is based on a coupled non-linear rate equation for the excited state of donors and acceptors and on a modified distribution function of interacting ions. The non-exponential decay of the fluorescene intensity just after flash excitation has been consistently understood as a result of the non-linear term of the rate equation by a numerical analysis. The transient and steady state fluorescence of Tb3+ in various glass matrices has been investigated as a function of the concentration of donors and acceptors, determining the physical parameters of the resonant enegy transfer process. This model is especially valid for analyzing systems with high donor-acceptor concentration and those under high excitation such as up-conversion laser materials.