High refractive index nanoantennas for efficient single photon generation from layered van der Waals materials

We demonstrate applications of high-refractive-index dielectric nanoantennas (NAs) for realization of bright single photon emitters (SPEs) in a monolayer WSe2 and few-nanometer-thick hBN. We realize several approaches for the efficient coupling of SPEs to NAs. First, we attach a monolayer WSe2 to NAs providing both optical enhancement and monolayer deformation, thus ensuring site-controlled formation of the SPEs and their efficient coupling to the near-field of the optical Mie modes and their far-field radiation. We use gallium phosphide (GaP) NAs etched from a monolithic GaP substrate, where we find very low (femto-Joule) saturation pulse energies and up to 10000 times brighter photoluminescence than in WSe2 placed on low-refractive-index SiO2 pillars. We also use van der Waals materials themselves to fabricate NAs. We realize this approach here using high-index WS2 NAs placed on a gold mirror, allowing enhanced collection efficiency of single photon emission above the substrate. Finally, we use an NA-on-a-mirror approach to simulate and realize nanocavities and enhance emission for SPE defects in a thin layer of hBN placed between a WS2 (or HfSe2) NA and a gold mirror.