ND-3+ TO ER-3+ AND ND-3+ TO HO-3+ ENERGY-TRANSFER IN LASER CRYSTALS

The fluorescence decay of the 4F3/2 state of the Nd3+ ions was studied in Nd3+, Er3+ and Nd3+, Ho3+ doped crystals of garnets and perovskites. Fast initial decays were observed in this system for the first time to our knowledge and are attributed to an energy transfer from the Nd3+ ion to the nearest codopant ions that can accept the energy. Mathematical models of the decay processes were tested, and agreement with the experimental data was obtained by including a short-range interaction responsible for the fast initial decay and a dipole-dipole interaction for the subsequent decay.