The goal of this research is to characterize the properties of crystals doped with optically active ions and pumped by laser excitation. The research can be divided into two thrust areas: characterizing the properties of long range energy migration among the doping ions and determining the rates of radiationless transitions between excited electronic states. The major experimental technique to be used in this work is four-wave mixing (FWM) spectroscopy. For the energy transfer studies this will be supplemented by time-resolved site-selection (TRSS) spectroscopy measurements, and for the radiationless decay studies this will be supplemented by picosecond pulse-probe measurements and by accumulated photon-echo measurements. The experiments will be performed on several chromium doped crystals that are important for laser applications. By correlating the information obtained in both of these areas, it will be possible to begin developing a detailed understanding of the spectral dynamics of optically pumped laser materials. By comparing the results obtained on each of the materials investigated, it will be possible to relate these characteristics to the properties of the host crystal. The knowledge gained from this type of detailed, systematic study is important to the continued development of laser and electro-optic technology.
