Spatially invariant optical-signal filters based on volume holograms

Abstract

An analysis is made of the physical basis of the processing of coherent optical signals with the aid of volume holograms. The coupled waves approximation is used to obtain a dynamic equation for the propagation of optical signals and of the associated noise in such holograms. An approximation solution of the dynamic equation is used to calculate the response of a volume hologram, recorded with the aid of a coded reference wave, to an arbitrary reconstructing signal. It is shown that such a hologram belongs to a new class of devies for the filtering of coherent optical signals, which are spatially invariant filters of the spatial frequencies. The main types of noise in a volume holographic filter are considered and the real dynamic range of the filter is estimated. An effective method for minimization of the filter noise is proposed.Methods for synthesis of a generalized filter transfer functions are discussed. A diagram is given for relating the main parameters of matched volume holographic filters recorded in the widely used photographic materials by a variety of methods.