Resolution limit for isotropic and anisotropic Bragg diffraction from finite holographic gratings

Abstract

We investigate light diffraction in a direction perpendicular to the surface of a photorefractive crystal by anisotropic or isotropic Bragg diffraction. We estimate the resolution limit by calculating the diffraction pattern as a coherent sum of waves that are diffracted from Fourier-transformed gratings. We show that the resolution limit for anisotropic and isotropic Bragg diffraction depends only on the thickness of the crystal and the ratio of the refractive index to the wavelength of the diffracted wave. We present experimental results for a KNbO3 photorefractive spatial light modulator with a resolution of more than 30 line pairs/mm.