ENERGY RELATIONS FOR SPACE-CHARGE WAVES IN PHOTOREFRACTIVE MATERIALS

An energy balance equation is derived with the aid of a partial differ ential equation describing the space-charge field in photorefractive m aterials. Expressions are found for power flux, losses, and the power absorbed from an external source both for the low- and high-frequency branches of space-charge waves. The efficiency of energy conversion fr om the external source into the space-charge wave is calculated and co mpared for two different mechanisms of optical excitation: (i) by a mo ving interference pattern and (ii) by a combination of a stationary in terference pattern and an external ac field. (C) 1996 American Institu te of Physics.