Chiral Optical Properties of Plasmonic Kagome Lattices
Xitlali G. Juarez, Francisco Freire‐Fernández, Siamak Khorasani, Marc R. Bourgeois, Yi Wang, David J. Masiello, George C. Schatz, Teri W. Odom
Abstract
Kagome lattices can be considered hexagonal lattices with a three-nanoparticle unit cell whose symmetry may lead to the formation of higher-order topological states. This work reports the emergence of polarization-dependent features in the optical band structures of plasmonic Kagome lattices through lattice engineering. By expanding the separations between particles in a unit cell while preserving lattice spacing, we observed additional modes at the K -points of aluminum nanoparticle Kagome lattices. As the rotational symmetry was reduced from 6- to 3-fold, a splitting at the K -point was observed as well as the presence of an additional surface lattice resonance (SLR) band under linear polarization. This SLR band also exhibited a chiral response that depended on the direction of circularly polarized light and resulted in asymmetry in the optical band structure. The polarization-dependent response of plasmonic Kagome lattices can inform the design of systems that support topological states at visible wavelengths.