All-optical logic gates based on insulator–metal–insulator plasmonic waveguides with octagonal nano-ring resonators

This study introduces the design and simulation of fully optical logic gates that employ insulator-metal-insulator (IMI) plasmonic waveguides featuring octagonal nano-ring resonators. The two-dimensional finite-difference time-domain (2D-FDTD) approach was applied for the analysis and simulations. In addition, the perfectly matched layer (PML) has been used as the boundary condition of the simulated region. The logic gates analyzed in this paper include NOT, OR, AND, NOR, NAND, XOR, and XNOR. The transmission threshold between logic 0 and logic 1 states is considered to be 0.25, which realizes all the seven logic gates in one structure and at a common wavelength of 1535 nm. The performance of these logic gates is based on constructive and destructive interferences. By changing the phase of the input signals of the structure as well as changing the input, control, and output ports, all these logic gates can be realized. Additionally, the contrast ratio is significantly high in most of the proposed logic gates, which is very desirable. The results obtained from the proposed structure are promising and it can be used in optical integrated circuits.