▎ 摘　　要

The spatial splitting and coupling between the edge modes in the graphene bend-ribbon waveguide are presented in this paper. We reveal a new phenomenon that the edge modes spatially split with the strongly confined even (odd) symmetric modal field shifts to the exterior (interior) edge of the waveguide, which is in stark contrast with conventional bend waveguide. Periodical couplings between the two edge modes due to the spatial splitting phenomenon have been described using the coupled mode theory. The theoretical results of coupled power and critical angles under different bend angles, waveguide widths, or chemical potentials are consistent with numerical simulations. Numerical calculations show that the bend-ribbon waveguide could achieve superior wave guiding with nearly no bending loss or field shift at smaller waveguide width, larger bend radius, or higher chemical potential. This work may provide a new perspective to understand the bending loss and modal coupling in the graphene bend-ribbon waveguide.