All-optical NOR and NOT logic gates based on ring resonator-based plasmonic nanostructures

Abstract

In this paper, compact all-optical plasmonic NOR and NOT gates have been proposed. The structures are based on metal-insulator-metal waveguides coupled to different plasmonic ring resonators. The fundamental structure used for design of the mentioned logic gates is based on T-shaped switches which consists of circular and octagon shaped plasmonic ring resonators (PRR). The simulation results show that the value of contrast ratios of NOR and NOT gates for circular-shaped PRRs are 23.37 and 19.42 dB and the value of contrast ratios of NOR and NOT gates for octagon-shaped PRRs are 24.37 and 23.12 dB, respectively. Also, the maximum transmission ratios of octagon- and circular-shaped PRR at the ON condition are about 82% and 76%, respectively. The proposed logic gates have been simulated using finite difference time domain (FDTD) method. It is observed that the octagon-shaped gates have higher transmission ratios and lower loss than the circular-shaped gates. The size of the NOT gates based on the circular- and octagon-shaped PRRs is 0.4422 µm2 and 0.4775 µm2, respectively. Also, the size of the NOR gate based on the circular- and octagon-shaped PRRs is 0.8645 µm2 and 0.9176 µm2, respectively. These optical logic gates can be used as key components in optical communications and for designing compact plasmonic devices.