Terahertz plasmonic SWAP and Fredkin gates utilizing graphene nano-ribbon waveguides

摘要

In this paper, terahertz plasmonic SWAP and Fredkin gates using the Si-SiO2-air-graphene-air structure deposited on the SiO2/Si substrate are presented and numerically studied. The presented terahertz plasmonic SWAP gate is composed of a symmetric Y-junction, two all-pass microring resonators, and a double series-coupled microring resonator, and the proposed terahertz plasmonic Fredkin gate comprises a three-arm Y-junction, three all-pass microring resonators, and a double series-coupled microring resonator. By flexibly adjusting graphene's chemical potential in rings, microring resonators' resonant states produce the change, then logic operations of SWAP and Fredkin gates can be correctly executed. Simulation results show that our designed terahertz plasmonic SWAP and Fredkin gates exhibit excellent extinction ratio and crosstalk. For the designed terahertz plasmonic SWAP gate, the extinction ratio can be greater than 20.92 dB and the crosstalk can be less than -21.38 dB. With input logic states of '000', '001', '010', '011', '100', '101', '110', and '111', the designed terahertz plasmonic Fredkin gate has a minimum extinction ratio of 21.65 dB and a maximum crosstalk of -21.15 dB.