Topological plasmonically induced transparency in a graphene waveguide system

Plasmonically induced transparency (PIT) is a physical phenomenon that mimes electromagnetically induced transparency in plasmonic systems. However, it is challenging to maintain its line shape with the presence of disorders or defects, mainly because it is highly susceptible to structural parameters. Herein, a two-dimensional graphene plasmonic system, which is composed of a few periods of vertically arranged graphene-nanoribbon (GNR) pairs coupled with a graphene waveguide, is proposed. By constructing GNRs to form bright and dark plasmon modes with topologically nontrivial phases, the optical response of the graphene waveguide system gives rise to robust PIT effects that exhibit an immunity to a certain degree of various parametric perturbations and imperfections. A three-level plasmonic system is demonstrated to explain the formation mechanism of the PIT effects, and the corresponding results agree well with the numerical ones. Combining topology with PIT helps to reduce the impact of parametric disorders and defects, which benefits the PIT devices with design freedom and higher stability.