A new class of optical materials for holographic storage and beam steering

Photorefractive materials have often been proposed as optical storage as well as optical interconnection media but attempts to build practical systems have been hindered by fundamental limitations of the materials themselves. Recently we have reported a new class of local photorefractive materials based on the properties of deep electron traps known as DX centers which occur in some doped compound semiconductors. These materials overcome many of the problems associated with the conventional materials showing 30 times larger refractive index changes, 60 times better sensitivity to exposing light, grating-period independent sensitivity, and an absence of erasure which normally occurs during multiple-grating exposures in conventional photorefractive materials. The price of all of these advantages is, at least for the present, that the effect in the new materials is persistent only at cryogenic temperatures. Work is underway to identify materials exhibiting these properties at room temperature.