Coherent Optical Logic by Laser Amplifiers With Feedback

An optical decision circuit is constructed by modifying the stability conditions of a previously introduced optical flip-flop memory (Appl. Phys. Lett., vol. 88, p. 181 118, May 2005). The simulations using a rate-equation model of the circuit predict fast operation speed (rise and fall times of the order of 20 ps are reached), which is most likely beyond the capabilities of recent semiconductor decision circuits that are suitable for integration (J. Lightw. Technol., vol. 24, p. 642, Mar. 2005). The decision characteristics are also better and close to the ideal digital response. They also enable realizing optical logic gates by using an interferometer and a single decision circuit. The output characteristics of an and and an or gate realized using the decision circuit are also studied