Persistent spectral hole burning of Sm 2+ and Eu 3+ ions in sol–gel derived glasses

Abstract

The persistent spectral hole burning (PSHB) properties were compared between Sm 2+ and Eu 3+ ions in glass. Al 2O 3 · 9SiO 2 glasses containing 2 wt% Sm 2O 3 and Eu 2O 3 were prepared by a sol–gel method of metal alkoxides and chlorides of rare-earth. The Sm 3+-containing glasses were heated in a H 2 gas to reduce to Sm 2+. The spectral holes were burnt in the 7 F 0 → 5 D 0 transition of both ions and the dependence of hole-depth on temperature was measured from 77 K to room temperature. Glasses containing both the rare-earth ions and OH groups were hole-burnt by the photo-assisted rearrangement of the OH bonds surrounding the rare-earth ions. The holes decreased the depth with increasing temperature from 77–200 K. In addition to this hole-burning process, the photo-excited ionization of the Sm 2+ ions formed a hole and thus the burnt-hole was not erased up to room temperature.