A photorefractive polymer based on poly(N-vinylcarbazole) photoconductive polymer was improved by use of plasticizer mixture of N-ethylerbazole and 1,3-biscarbazolylpropane. The modified photorefractive polymer was applied to the nonlinear materials for a matched-filter four-wave-mixing optical correlator. The operation of image correlation was demonstrated with the 10:1 of signal-to-noise ratio.