We present the first complete theoretical model that describes the formation of the space-charge field in a photorefractive material that is exposed to a sinusoidal ac electric field with a dc offset and a running light-interference pattern. The model is complete in the sense that it is valid for all time scales and hence also covers situations in which the well-known period-averaging technique is inapplicable. For large temporal frequencies of the ac electric field the solution is shown to converge with that obtained from the period-averaging technique. It is shown that by imposing a running interference pattern and a sinusoidal ac electric field simultaneously, it becomes possible to enhance certain frequency components selectively. Experiments are performed to confirm the theoretical findings, and good agreement is obtained.
© 1998 Optical Society of America
Per Michael Johansen and Henrik C. Pedersen, "Photorefractive space-charge field with running grating and applied sinusoidal ac electric field: solution for all time scales," J. Opt. Soc. Am. B 15, 1366-1374 (1998)