Theory of space-charge field with a moving fringe in photorefractive polymers

Resonance of space-charge field can occur in photorefractive polymers throu gh a moving fringe and can be described by a forced oscillation equation wi th damping. The resonance frequency and the magnitudes of both the amplitud e and the imaginary part of the space-charge field at the resonance frequen cy are functions of three experimental parameters: total incident intensity , applied electric field, and grating wave vector. Thus, the diffraction ef ficiency of grating and the gain coefficient of two-wave mixing are depende nt on the three experimental parameters. Our theory can also be applied to inorganic photorefractive crystals. (C) 2001 American Institute of Physics.