An investigation of an ultrafast 3-bit all-optical binary to gray and gray to binary code converters based on an interference effect in 2D photonic crystal platform

This work proposes a unique and compact architecture for a 2D photonic crystal (PhC) based all-optical 3-bit binary to gray and gray to binary code converters (BGCC and GBCC). The proposed designs incorporate all-optical XOR gates operating at a wavelength of 1.55 mu m with air holes in a silicon background arranged in the hexagonal (triangular) lattice structure. The linear interference effect is the basis for operation for the proposed all-optical 3-bit BGCC and GBCC in which the input beam phase is maintained at phi = 0(0) while appropriate phase difference is introduced at reference ports 1, 2, resulting in minimal power consumption. The proposed architectures are aimed to be scalable and compatible with Optical Integrated Circuits (OICs) while simultaneously reducing the size. In order to compute and analyse the specified performance metrics, the Plane wave expansion (PWE) and Finite Difference Time Domain (FDTD) approaches were implemented. The proposed designs have been optimized with respect to their structural parameters, namely, the radius of holes and lattice constant. All-optical XOR gates have been cascaded in a single stage to design the proposed all-optical 3-bit binary to gray code and gray to binary code converters. The simulation results show that the all-optical 3-bit binary to gray code and gray to binary code converters have shown 12.88 and 22.06 dB of contrast ratio, 0.32 and 0.76 ps of response period and a high bit rate of 3.12 and 1.31 Tbps respectively.