Design of silicon slab waveguides based all-optical logic gates

Logic gates are an indispensable part of digital circuits, and therefore such devices with fast operating speeds and simple designs are vital for all kinds of electronic applications. This paper proposes simple Y-shaped designs of all-optical AND, OR, and NOT logic gates in two dimensions that are operational in both TE and TM modes. These gates are designed using silicon slab waveguides, which makes them relatively easy to fabricate. The logic gates are designed, analyzed, and optimized at 1.55 mu m using the finite difference time domain method. The truth tables of the proposed all-optical logic gates are realized for every input case. The propagation delay time is determined to be of the order of femtoseconds (10-15 s), which is very fast compared to the response time of the currently reported all-optical logic gates (10-9 - 10-12 s).