Guided modes in a triple-well graphene waveguide: analogy of five-layer optical waveguide

We illustrate that a triple-well potential structure on a monolayer graphene can be treated as a five-layer optical waveguide. The transfer matrix method was used to deduce the dispersion equation for the graphene waveguide. It is found that the results have the similar dispersion equation, equivalent to the transverse electric wave in dielectrics. The symmetric and anti-symmetric oscillating guided modes are determined and studied in details for the triple-well potential. From the results, we conclude that the oscillating guided modes appear either in the middle well or in all three wells. The results may be helpful in designing various novel graphene-based devices, such as electronic fiber and directional coupler.