SPIN-FLUCTUATION-INDUCED OPTICAL SPECTRAL DIFFUSION IN PR3+-YALO3

We report a quantitative study of spectral diffusion in a solid-state system by measuring the stimulated echo relaxation. The spectral diffusion process in Pr3+:YAlO3 at low temperatures (2.0 K) is found to be dominated by the relaxation of the "frozen core" of nearest-neighboring Al spins. The decay of the echo signal is found to be fully described by a simple spin-flip diffusion model and by a first-principle calculation. The complete understanding of the spectral diffusion process in this simple model system establishes a quantitative basis for using coherent optical techniques to study slow dynamics in complex systems.