Photorefractive properties of periodically poled LiNbO3

We study theoretically the photorefractive response of periodically poled LiNbO3 crystals with dominating photovoltaic transport. Strong suppression of the photorefractive effects at low spatial frequencies (in comparison with the single-domain case) and preservation of these effects for short fringe spacings are shown. We also describe a new kind of photorefractive wave coupling, which is forbidden for single domain crystals. It is characterized by wave propagation angles, dependent on the domain inversion period, and by a large gain factor