Interaction of chiral light with topological singularities in plasmonic metasurfaces

Topological insulators (TIs) are electronic materials that have a bulk band gap but have protected (even in the presence of disorder) conducting states on their edge or surface. They provide unprecedented platform for quantum computation among other applications. During the past decade, the concepts of topological physics have been introduced into other fields, including photonic systems and efficient light confinement, guiding and localization have been achieved by using photonic crystal (PhC) optical systems with topological states. Furthermore, surface plasmon (SP) polaritons are 2D surface waves confining electromagnetic energy to subwavelength regions in the vicinity of a metal-dielectric interface. The SP's properties can be manipulated by causing them to interact with properly designed nanoscale metasurfaces and as these can by fabricated at great ease today, SPs play a vital role in nano-optics. Here we present simple metasurfaces with different topologies supporting plasmonic edge states at the boundary between them. Preliminary experiments and numerical simulations show the achieved mode localization in line defects and point singularities. Line singularities are shown to support dark and bright modes. Point singularities show strong localization of light which can be further modified by the varying topological order of the structure.