Optimal Properties Of Photorefractive Materials For Optical Data Processing

Optimal properties of photorefractive materials for optical data processingGeorge C. Valley and Marvin B. KleinHughes Research Laboratories, 3011 Malibu Canyon Road, Malibu, CA 90265AbstractThe charge transport model of photorefractivity is used to evaluate four figures of meritthat can be used to characterize the performance of photorefractive materials. The figuresof merit are the steady -state index change, the response time, the energy per area to writea grating with one percent diffraction efficiency, and the index change per absorbed energyper unit volume (photorefractive sensitivity). These indices are evaluated as a function ofgrating period and applied external electric field for Bi12SiO20, a fast material with arelatively small electro -optic coefficient and BaTiO3, a slower material with a much largerelectro -optic coefficient. Methods for optimizing the materials are discussed.IntroductionPhotorefractive materials such as lithium niobate (LiNbO3), potassium niobate (KNbO3),'barium titanate (BaTiO3), strontium barium niobate (SBN) and bismuth silicon oxide(Bi12SiO20) are attractive new candidates for real -time optical data processing, (ODP);