Abstract

One major limitation of photorefractive crystals is their relatively slow response time at reasonable light intensities [1]. In this paper we present a time integrating correlator using a photorefractive crystal which uses the slow response time of the crystal to its advantage. Specifically, we show that the response time is equivalent to the integration period of the correlator. An increase in the response time of the crystal will thus correspond to a longer integration time and consequently a larger processing gain for the system. Hence, inputs with very low signal to noise ratios can still be detected. In addition to the temporal aspect, the correlator uses the high recording bandwidth of the photorefractive effect to allow processing of signals of high time-bandwidth products, as well as to give the system the ability of presenting correlation outputs without bias. Experimental results for the photorefractive time integrating correlator are presented.

© 1987 Optical Society of America