ALL-OPTICAL NONLINEAR JOINT FOURIER-TRANSFORM CORRELATOR

We present the first all-optical nonlinear joint transform correlator based on a square-law receiver in the Fourier plane. Our device uses a photorefractive limiting quadratic processor. The compressional nonli nearity associated with the transfer function of the limiting quadrati c processor enables the correlator to detect signals embedded in Gauss ian and non-Gaussian noise. In the limiting region this device correla tes the phase-only information of the input. This is the first time to our knowledge that photorefractives or real-time holography has been used in the correlation of the phase-only information. We demonstrate the operation of this device experimentally, and we evaluate its perfo rmance through computer simulation for various forms of noise.