Reversible polarized bleaching in hydrogenated rare-earth-doped fluorites

By using site-selective laser spectroscopy, several sites in hydrogenated and deuterated rare-earth-doped fluorite crystals have been found to exhibit reversible bleaching. The site orientations can be switched between orthogonal directions by corresponding changes in the laser polarization. Such effects are a form of photochemical hole burning and are attributed to laser-induced migration of H(-) or D(-) ions between equivalent interstitial positions adjacent to the rare-earth ion.