Spin-orbit interactions in plasmonic crystals probed by site-selective cathodoluminescence spectroscopy.

The study of spin-orbit coupling (SOC) of light is crucial to explore the light-matter interactions in sub-wavelength structures. By designing a plasmonic lattice with chiral configuration that provides parallel angular momentum and spin components, one can trigger the strength of the SOC phenomena in photonic or plasmonic crystals. Herein, we explore the SOC in a plasmonic crystal, both theoretically and experimentally.

Mapping optical Bloch modes of a plasmonic square lattice in real and reciprocal spaces using cathodoluminescence spectroscopy.

Strong electron-light interactions supported by the surface plasmon polaritons excited in metallic thin films can lead to faster optoelectronic devices. Merging surface polaritons with photonic crystals leads to the formation of Bloch plasmons, allowing for the molding of the flow of polaritons and the controlling of the optical density of states for even stronger electron-light interactions. Here, we use a two-dimensional square lattice of holes incorporated inside a plasmonic gold layer to investigate the interaction of surface plasmon polaritons with the square lattice and the formation of plasmonic Bloch modes.