Abstract

Encoding photorefractive diffraction gratings in optically thin¹ and thick² samples has recently been demonstrated in doped semiconductors containing DX centers. The optically induced index change in these materials is believed to result from photoionization of DX centers, resulting in a persistent change in the free-carrier concentration, which alters the refractive index through the the plasma effect. This effect offers several advantages over traditional photorefractive systems for optical information-storage applications, such as large index changes (Δ > 0.01), high sensitivity (>10⁻² cm²/J), no beam fanning, and linear superposition of encoded gratings. Several of the benefits arise directly from the local nature of the writing process, which we have now verified in the experiments reported here.

© 1995 Optical Society of America