Higher-order topology in plasmonic Kagome lattices

We study the topological properties of a Kagome plasmonic metasurface, modeled with a coupled dipole method that naturally includes retarded long range interactions. We demonstrate that the system supports an obstructed atomic limit phase through the calculation of Wilson loops. Then, we characterize the hierarchy of topological boundary modes hosted by the subwavelength array of plasmonic nanoparticles: both one-dimensional edge modes and zero-dimensional corner modes. We determine the properties of these modes, which robustly confine light at subwavelength scales, calculate the local density of photonic states at edge and corner modes frequencies, and demonstrate the selective excitation of delocalized corner modes in a topological cavity, through nonzero orbital angular momentum beam excitation.

Automated summary

This study investigates the topological properties of a Kagome plasmonic metasurface, demonstrating the support for an obstructed atomic limit phase and characterizing the hierarchy of topological boundary modes hosted by a subwavelength array of plasmonic nanoparticles. It also showcases the properties of these modes, such as robust light confinement at subwavelength scales, and shows the selective excitation of delocalized corner modes in a topological cavity through nonzero orbital angular momentum beam excitation.