Efficient guiding mid-infrared waves with graphene-coated nanowire based plasmon waveguides

A graphene-coated nanowire (GCNW) based plasmon waveguide is proposed to achieve outstanding guiding performance in the mid-infrared band. The modal properties of the fundamental graphene plasmon mode and modal dependence on the elliptical nanowire size, thickness and width of the low-index dielectric layer, chemical potential of graphene and the operating frequency are revealed in detail by using finite element method. Results show that the low-index layer has a significant influence on modal properties, and a propagation length over 13 mu m along with an extremely small normalized mode size (similar to 10(-6)) could be obtained simultaneously, which is more than two orders of magnitude smaller compared with free-standing GCNW and GCNW dimers. Besides, study on crosstalk characteristics between the adjacent structures indicates the proposed waveguide exhibits very low crosstalk. Due to these excellent transmission characteristics, the proposed configuration could be used to fabricate various functional photonic devices for the future nanoscale photonic integrated circuits.