Abstract

We report evidence that rare-earth ion-doped YLF laser systems are more complex than usually thought. It is generally assumed that the rare-earth ion dopant occupies a single center with the (S₄) symmetry of the Y³⁺ ion it replaces. Although the substitution creates a lattice distortion because of ion-size mismatch, it is usually assumed that dopants are sufficiently well separated to prevent the perturbation of other nearby dopant ions. However, we find that there are actually several spectrally distinct subsets of rare-earth ions with different crystal field environments and transition wavelengths. Low-temperature, high-resolution laser spectroscopy reveals that these dopant subsets (or centers) may have comparable importance to the "isolated ion" center.

© 1991 Optical Society of America