Abstract
Diffraction from volume reflection gratings written in bulk photorefractive lithium niobate is modeled for the case of longitudinally varying index modulation depths. Numerical solutions to the Helmholtz equation are found in the spatial frequency domain, leading to transfer functions for the volume reflection grating. These transfer functions are then used to show the spatial frequency filtering effect of the volume reflection grating on input light fields containing 2D spatial information. It is shown, first through simulations and then by experiment, that the 0th order transmitted beam undergoes a 2D edge enhancement.