Chiral and hyperbolic plasmons in novel 2-D materials

The advent of novel 2-D materials has brought to the spotlight the subject of surface polaritons in these materials. It is the goal of this chapter to provide a brief overview of the topic with the emphasis on isotropic, anisotropic, hyperbolic, and chiral plasmons. We derive dispersion equations for the plasmons in general 2-D material described by 2 × 2 conductivity tensor and discuss the concept of k-surfaces crucial for understanding properties of guided modes in anisotropic materials. We supplement results of the analysis by numerical simulations of the surface plasmons excited in the 2-D materials. We demonstrate that anisotropy and hyperbolicity allow for highly directional guiding of the plasmons in the form of subdiffractional beams. We discuss implications of the chirality for unidirectional guiding of the plasmons.