Photorefractive spatial light modulation by anisotropic self-diffraction in KNbO_3 crystals

Abstract

Photoinduced anisotropic self-diffraction in photorefractive KNbO3 has been studied. It has been shown that this type of diffraction is ideally suited for spatial light modulation or incoherent-to-coherent conversion. A phase grating that is photoinduced by two coherent light beams causes the diffraction of one of the beams. By spatially modulating the amplitude of the phase grating with an incoherent signal beam it is possible to transfer an incoherent image onto the coherent self-diffracted beam. The performance parameters of this modulator are described with a simple model.