Abstract: A subpicosecond solid state optical correlator based on interference induced carrier modulation includes a photosensor circuit having a photoconductive element and a pair of opposed electrodes. A voltage difference is created across the electrodes to define an electrical field direction, and the element operates to generate charge carriers in response to optical energy incident on the photoconductive element. First and second optical signals are directed onto the photoconductive element to form an interference pattern thereon when the signals overlap in time and space. This interference pattern produces spatial modulation of the distribution of the carriers into lines or planes, at least some of which are not parallel to the electrical field direction. The resulting photocurrent is monitored to detect a parameter associated with the presence or absence of the interference pattern.