9307849 Bray The theme of this research project is the use of high pressure to alter the dopant-lattice and dopant-dopant interactions responsible for defining optical properties of YAG doped with Cr3+, Tm3+, and Ho3+, separately and in combination. Pressure will be used to perturb the local bonding environments of Cr3+, Tm3+, and Ho3+ in YAG, and experiments will be conducted to monitor the effects of pressure on optical properties. The effect of pressure on the dopant bonding environment will be characterized so that structure-property correlations for YAG based solid state laser materials can be developed. Absorption, excitation, cw photoluminescence, and time-resolved photoluminescence experiments will be performed as a function of pressure. The effect of pressure on energy levels and splittings, optical transition intensities, luminescence lifetimes and efficiencies, and ion-ion energy transfer processes will be characterized. Processes to be studied include Cr3+-Tm3+, Cr3+-Ho3+, and Tm3+-Ho3+ energy transfer, Tm3+-Tm3+ energy migration and cross-relaxation, and Ho3+ upconversion. %%% This research aims to improve fundamental understanding of solid state laser materials. These materials are important in applications in the areas of medicine, optical fiber communications, solar energy, and imaging. High pressure will be used to modify material structure, and changes in optical properties as a function of pressure will be studied experimentally. The research is expected to provide the molecular information needed to understand the relationship of chemical composition and structure to the laser properties of garnet based materials. ***
