Abstract

We report the results of time–resolved optical holeburning of Er³⁺ ions in YLiF₄ (0.02%). In earlier work for H//c we described the time evolution of holes burned at 33kG using laser scanning over a frequency of 40MHz¹ and we reported, using larger scans, the occurence of optical side holes. We now describe results for H_⊥c with scans > 400 MHz using a new Zeeman technique for frequency scanning the optical transition frequencies which allow one to study the time evolution of the holes and their associated sideholes. The hole lineshapes evolve with time reaching a linewidth of ≃ 10 MHz after 600 μs. We identify the source of the time evolution of the hole shape as spectral diffusion resulting from mutual spin flips of the surrounding fluorine nuclei whose flip rates are strongly modified from the bulk rates by the presence of the large magnetic moment of the Er³⁺ ion which produces a "frozen core". A computer simulation which takes into account the details of the dynamics of the frozen core successfully describes the time evolution of the holes, confirming the dominant role of F nuclear spin flips.

© 1991 Optical Society of America