DISCOVERING ENERGY-TRANSFER PATHS IN LASER CRYSTALS

We demonstrate a new technique for discovering the main mechanisms of energy transfer inside the active It consists of measuring the harmoni c content of fluorescence when the pump In particular we discuss excit ed-state absorption and upconversion and present the equations for the fundamental and the second harmonic for both of these processes. We m easured the fluorescence from the S-4(3/2) multiplet of Er3+ in three hosts, YLF, YAG, and CaSGG, with different doping. The results of the new method show that we are able to identify which multiplets transfer their energy to the observed one and through which process. (C) 1997 Optical Society of America.