Photonic-crystal-based design and FDTD simulation of all-optical NAND and NOR gates with improved contrast ratio

Abstract

The proposed research reports the simulation of a photonic crystal (PhC) ring-resonator-based full-optical NAND and NOR gate design. The designed structure comprises a 18 × 30 square lattice dielectric silicon rod-type PhC with a refractive index of n = 3.46. An interatomic distance ‘a’ of 560 nm, radius ‘r’ of 0.21a (0.133 μm) and input wavelength λ = 1550 nm with an input signal amplitude of 1 volt are used in this design. The proposed structure provides two large band gaps in Transverse Electric polarized mode in the ranges of 1342–1980 nm and 758–779 nm. Similar parameters are used for both NAND and NOR logic gate designs. The functionality of the proposed full-optical gates depends on the ring resonator principle and the intensity of the incident light. Numerical analysis of the simulation is based on the finite difference time domain method, whereas band gap analysis is performed using the plane wave expansion method.