High-resolution incoherent-to-coherent conversion by use of the photorefractive fanning effect

We demonstrate that high-resolution incoherent-to-coherent conversion can be carried out in an incoherent-to-coherent converter based on the photorefractive fanning effect. The output coherent image has the same direction as the incident coherent beam, and thus the resolution is not limited by the grating diffraction. We obtained a resolution as high as 90.5 line pairs/mm in this experiment. The transmittance of the coherent beam relative to the intensity of the incoherent beam was measured. We also theoretically estimated the resolving power with respect to the interaction length. The numerical results agree well with the experiments.