Nuclear spin-flip sidebands in optical spectral holeburning and fluorescence line narrowing of the Er³⁺ ion

We have observed fine-structure in the optical spectrum of the Er3+ ion in YAlO3, YLiF4, and LaF3, which originates from an electronic transition on the Er3+ ion together with a nuclear spin flip on one of the host nuclei, here 7Li, 19F or 27Al. The resolution necessary to observe these nuclear spin-flip sidebands was obtained using spectral holeburning and fluorescence line narrowing at 1.6 K. The nuclear magnetic moments are modified by the superhyperfine interaction. © 1991.