PHOTOREFRACTIVE 2-BEAM-COUPLING NONLINEAR JOINT-TRANSFORM CORRELATOR

An all-optical nonlinear joint-transform correlator that is based on a square-law receiver has been implemented for the first time to our kn owledge without the use of a spatial light modulator and digital proce ssing in the Fourier plane. The correlator uses energy transfer from t wo-beam coupling in the Fourier plane. We implement compressional nonl inearity in the hard-clipped regime by pumping a weak plane wave with the intense joint spectrum of the reference and the signal images. Ope ration of this device rivals or exceeds that of the phase-only filter for detecting objects in cluttered noise. Experimental results are com pared with both plane-wave and beam-propagation simulations.