▎ 摘　　要

In this paper, we theoretically show that high-performance and low-loss mid-infrared plasmon waveguiding can be achieved by introducing a thin low-index buffer layer between a graphene-coated nanowire and a silicon substrate. It is found that the introduction of the buffer layer can mediate the coupling between the nanowire and substrate, and it can effectively suppress the leaky radiation to the substrate. According to the results, by choosing an ultra-small buffer thickness and gap distance and also by fine-tuning the nanowire and graphene parameters, a low propagation loss (0.312 dB/mu m) with improved figure of merit can be realized simultaneously. Our findings are important for the optimum design of substrate-supported graphene-based cylindrical waveguides. (C) 2016 Optical Society of America