Line Waves and Unidirectional Propagation on Metasurfaces

We have developed a new kind of waveguide in which the modes consist of the interface states between two complementary impedance surfaces. It is analogous to two-dimensional surface waves, which are bound to the planar interface between two media, but in this case the waves are bound to the one-dimensional line interface between two sheets. They have several important properties, including a field singularity, and unidirectional propagation of two orthogonal modes, such that the polarization is locked to the propagation direction. We will examine how they are realized using metasurfaces, and their relationship to other media such as photonic topological insulators and chiral materials.