▎ 摘　　要

We theoretically investigate the localized surface plasmon of graphene in graphene-cavity-coupled waveguide system with using finite-difference time-domain (FDTD) method and the coupled mode theory (CMT). Cavity provides the strong light-matter interaction between graphene and light. And strongly confined radiation can be confined in a thin and finite width graphene. The fermi level of the graphene nanoribbon plays an important role in tuning the graphene surface plasmon. The faint high-order mode of graphene surface plasmon is also observed. The resonant wavelengths of graphene surface plasmon are almost unaffected by the altering of the refractive index of the cavity core, susceptibility of the cavity core and intensity of incident light. This paper can give an insight of the localized surface plasmon properties in graphene system or any other 2D system. And graphene assisted with cavity is an attractive candidate for designing active graphene plasmonic devices or any other 2D plasmonic devices.