The optical disk is a computer-addressable binary storage medium with very high capacity. More than 1010 bits of information can be recorded on a 12-cm-diameter optical disk. The natural two-dimensional format of the data recorded on an optical disk makes this medium particularly attractive for the storage of images and holograms, while parallel access provides a convenient mechanism through which such data may be retrieved. In this paper we discuss a closed-loop optical associative memory based on the optical disk. This system incorporates image correlation, using photorefractive media to compute the best association in a shift-invariant fashion. When presented with a partial or noisy version of one of the images stored on the optical disk, the optical system evolves to a stable state in which those stored images that best match the input are temporally locked in the loop.
Tobias Kippenberg, Camille Sophie Brès, Davide Grassani, Martin Hubert Peter Pfeiffer, Svyatoslav Kharitonov, Adrien Billat