Analysis and Design of Graphene-Based Surface Plasmon Waveguide Switch at Long-Wavelength Infrared Frequencies

A graphene-based surface plasmon (SP) waveguide switch is designed at near infrared frequencies. First, graphene is modeled in electronic and electromagnetic solvers, in order to use graphene strips for designing the waveguide. Because of finite size of these strips, propagating surface plasmon polaritons (SPPs) along them exhibit spatial dispersion. By considering this and shifting interband losses to higher frequencies (by doping the graphene strips), the waveguide switch is designed to operate at 30 THz. In this paper, chemical potential in the graphene strips is controlled through applying back and top gate voltages which provide a reconfigurable waveguide switch and the chemical potentials of the strips are changed so that ultra-confinement and extremely low-loss propagation are achieved. The designed switch provides extremely low return loss and ultra-bandwidth in 30--40 THz frequency range. Due to the spatial dispersion in the graphene strips, new procedures are proposed to calculate the return and insertion losses of the switch and also absorbed power in the graphene strips.