Controllable intermodal coupling in waveguide systems based on tunable hyperbolic metamaterials.

Abstract

In this work, we study intermodal coupling in a waveguiding system composed of a planar dielectric waveguide and a tunable hyperbolic metamaterial waveguide based on graphene, which has not been yet investigated in this class of waveguide system. For this purpose, using the Lorentz reciprocity theorem, we derive coupled mode equations for the considered waveguiding system. We demonstrate, for the first time, possibility of a fully controlled power exchange between TM modes of the dielectric waveguide and both forward and backward TM modes of the hyperbolic metamaterial waveguide by changing Fermi potential of graphene. In the course of our analysis, we also investigate how the system parameters, such as waveguide width and separation distance, influence the strength of intermodal coupling.