Investigation of edge plasmon modes in graphene-black phosphorus double layer strip waveguides

In this paper, we investigate the theoretical aspects of edge plasmon modes in a waveguide that utilizes a double layer strip composed of graphene and black phosphorus (G-BP). Here, we focus on the influence of the black phosphorus edge molecular configuration on the properties of these plasmonic modes. Unlike graphene, the anisotropy of black phosphorus significantly impacts the modes. Specifically, edge plasmons propagating in the armchair direction exhibit relatively low losses, while modes propagating in the zigzag direction exhibit stronger field confinement near the black phosphorus layer. By selecting appropriate parameters such as the operation wavelength, black phosphorus doping level, and graphene Fermi energy, the characteristics of the edge plasmon modes in the proposed waveguides can be effectively controlled. Furthermore, the study reveals that monolayer black phosphorus nanoribbons placed on low refractive index dielectric substrates are favorable for plasmonic applications due to the low losses observed in the edge modes. The results obtained from this investigation contribute to the advancement of integrated plasmonic devices that rely on the combination of graphene and black phosphorus.