Optical delay circuit having optical loop for repeatedly introducing delay time between input data and output data and method used therein

摘要

An optical delay circuit includes an optical loop for repeatedly introducing a unit time delay into propagation of parts of an input optical signal representative of pieces of data information; when the optical loop introduces a time delay to be required for one of the parts, a controller instructs an optical switch inserted in the optical loop to transfer the part to an output optical circuit so that the optical delay circuit occupies small space.