Realization of all-optical NAND and NOR logic functions with photonic crystal based NOT, OR and AND gates using De Morgan’s theorem

Abstract

In this article, we propose the realization of photonic crystal based all-optical universal logic gates, NAND and NOR with basic logic gates viz. NOT, AND and OR in two level logic using De Morgan’s theorem. As per the theorem, NAND or NOR gate can be designed with two NOT gates in first level, cascaded to a second level OR gate or AND gate, respectively. Initially, the basic logic gates are designed and optimized such that their implementation in the design of NAND and NOR gates cannot degrade the threshold value of logic levels. Length of the input waveguides in each design is kept common so as to have a change in the interference of the input signals with a phase difference of 0° and 180°. The proposed basic logic gates are resulted with a contrast ratio of 11.04, 8.24, and 5.18 dB, respectively. While the calculated values of contrast ratio of NAND and NOR gates are 5.81 and 4.02 dB, respectively. Moreover, the bit rate of the proposed designs is above 7.485 Tbps which shows their inevitable usage in high speed data communication networking.