Numerical Investigation of Slow Light Propagation in Graphene-Based Waveguides

In this paper, electronic modeling and electromagnetic modeling of graphene nanoribbons (GNRs) are rigorously investigated. From the electronic point of view, a GNR is modeled through its linear band diagram; in this regard, the GNR is doped electrostatically in a waveguide configuration. Then, the capacitance of this waveguide is computed according to the associated band diagram. From the electromagnetic point of view, the GNR is considered as a conducting sheet, which is characterized by an effective conductivity. Then, a waveguide switch comprised of three GNRs is designed, which supports TM-polarized surface plasmon polariton propagation modes at 30 THz. To reach a miniaturized structure, the group velocity of plasmons is decreased to be comparable with Fermi velocity in graphene; consequently, an effective conductivity model is required to accurately predict propagation of slow waves in the GNRs. Finally, this conductivity model is verified by proposing a nonlocal circuit model.