▎ 摘　　要

In this paper, a new type of plasmonic waveguide consisting of two vertically coupled double-graphene-coated nanowires integrated with a thin high-index dielectric substrate is designed. The transmission properties of the surface plasmon polaritons supported by the waveguide are investigated by the finite element method (FEM). Theoretical investigations reveal that deep-subwavelength mode confinement as well as long-range propagation length can be achieved simultaneously in the studied structure through optimizing the geometric and electromagnetic parameters. The comparisons of the mode properties between the proposed waveguide and waveguides studied in the published literatures are also considered. This structure has potential applications in ultra-tight optical integration field.