Time-resolved site-selection spectroscopy investigation of Y3(Al/sub 1-x/Ga/sub x/)5O12 : Nd3+ crystals

We have used selective laser excitation techniques to investigate the spectroscopic properties of Nd3+ ions in Y3(Al/sub 1-x/Ga/sub x/)5O12 crystals and found the mixed crystal nature of the host produced both distinct structure and inhomogeneous broadening in the Nd3+ spectra. We employed time-resolved spectroscopy measurements to characterize energy transfer between Nd ions in nonequivalent crystal field sites and the results are consistent with the migration of energy among Nd ions in the dominant type of site with trapping occurring at Nd ions in defect sites. The migration and trapping processes require thermal activation and are consistent with a two-phonon assisted energy transfer mechanism. The efficiency of energy transfer is greater in mixed crystals than in unmixed garnet hosts, and it is shown that this is associated with the increase in the transition matrix elements in the mixed crystals