Fundamental Limit of the Speed of Photorefractive Effect and its Impact on Device Applications and Material Research - Comment

This comment on the fundamental speed limitations in photorefractive materials is written in response to a publication by P. Yeh. We point out that the fundamental speed limitations are due to the drift or diffusion time of photoexcited carriers in the presence of a spatially varying optical intensity. In contrast to Yeh's conclusion, there still exists considerable room for improving the performance of practical photorefractive materials.