Optimization of an all-optical three-input universal logic gate with an enhanced contrast ratio by exploiting a T-shaped photonic crystal waveguide.

Abstract

Universal gates (NAND and NOR) are used for any electronic circuit that is affordable and straightforward to build all logic gates (LoG). In this work, the T-shaped 2D photonic crystal (PhC) is exploited to design a three-input universal LoG premised on the beam-interference principle. The design criteria of pitch (a), rod radius (r), and refractive index (n) are employed to obtain a high impact output. The methodologies of plane wave expansion and finite-difference time-domain are employed for examining the framework of universal LoG at 1550 nm wavelengths (λ). The suggested universal LoG design has a compact size of 8.4µm×4.8µm. Additionally, the structure yields a high contrast ratio (CR) of 20.37 dB for the NAND LoG and 28.45 dB for the NOR LoG, and maximum transmission efficiency of 50.6% and 70% for the NAND and NOR gates; correspondingly, the best and worst three-input NAND gate response times are 19.5 ps and 21.4 ps. Similarly, the response time of the three-input NOR gate is 26 ps. The proposed universal gate's primary goal is to offer a high CR and a compact structure while being compatible with any other logic gate.