Abstract

The spectral hole-burning in rare-earth doped crystals has been usually ascribed to the optical pumping of the hyper-fine sublevels. In contrast to the crystals, the holes in glasses have quite different character; the hole width is broad and the thermal stability is high. The hole burning mechanism in glass is believed to be a small lattice rearrangement around the rare-earth ions.¹ In other words, the rare- earth ions couple with the neighboring two level systems (TLS) of structural origin. In spite of apparent success of this interpretation, we have had no direct evidence for the role of TLS on the hole properties. To clarify this point, we made a comprehensive study in several inorganic materials containing various degree of disorder, which we can control intentionally.

© 1995 IEEE