ELIMINATION OF SCATTERING CENTERS FROM CR-LICAALF6

We describe the morphology of micron-sized defects present in all samples of the the laser crystal Cr3+:LiCaAIF6 (LiCAF). We further describe the results of a set of annealing experiments which demonstrate that annealing within 50-degrees-C of the melting point eliminates these defects and reduces passive scattering losses in the crystal by an order of magnitude. We present evidence which shows that during annealing, these defects dissolve into the matrix and then diffuse out of the crystal. We estimate that the diffusion constant for the atomically dispersed defect species is on the order of 10(-7) cm2/s. Finally, we hypothesize a mechanism for the growth and elimination of defects in LiCAF.