LOCALIZED SWITCHING IN PHOTOREFRACTIVE FERROELECTRICS INDUCED BY SPATIALLY INHOMOGENEOUS ELECTRIC-FIELDS

We examine theoretically the stability of 180 degrees domain patterns that may form inside photorefractive ferroelectric crystals when an op tically induced spatially modulated electric field is present. By anal yzing the total free energy of a ferroelectric crystal subjected to an applied field and with free charges contained within, we find under w hat conditions (magnitude of the applied field, amplitude of the optic ally induced electric held, and domain-wall energy density) the sponta neous polarization of the crystal tends to switch throughout the whole crystal and under which only partial switching occurs. (C) 1998 Ameri can Institute af physics.