Metasurface of strongly coupled excitons and plasmonic arrays

Metasurfaces allow to manipulate light at the nanoscale with planar lenses and holograms as prominent applications. Integrating metasurfaces with transition metal dichalcogenide monolayers provides additional functionality to ultrathin optics, such as tunable optical properties and enhanced light-matter interaction. Here, we developed a novel fabrication method that allows to directly integrate such a monolayer with a plasmonic lattice without compromising optical quality or coupling strength, by embedding the gold nanodisk array into an encapsulating hBN layer. We demonstrate plasmon-exciton-polaritons in this metasurface with a large Rabi splitting and strongly modified polarization and emission characteristics, as compared to a bare monolayer, achieving narrow-angle, directional, linearly polarized emission.