Grating response time of photorefractive KNbO3:Rb+

Photorefractive crystals play an increasingly important role in optical information processing. Some of these crystals have been used in a variety of optical computing applications. The photorefractive response time is a critical issue because it directly determines the processing speed of the devices. Crystals that are widely used at present, such as BaTiO₃, LiNbO₃, and SBN, etc., are relatively slow when the light intensity is 1 W/cm². Semiconductor crystals such as GaAs and GaP have a higher speed but suffer from small coupling constants. For high processing speed, KNbO ₃ has the best promise because it has the highest figure of merit among the oxide photorefractive crystals. Volt et. al studied the photorefractive response time of KNbO₃:Fe. They found that reduction of the crystal could decrease the response time by several orders of magnitude. However, such KNbO₃ crystals often become optically inhomogeneous after reduction. In this paper, we report our investigation of the transient photorefractive response of KNbO₃:Rb⁺ crystals, which exhibit a fast response time while maintaining a significant gain and good optical homogeneity for information processing applications