Transition metal dichalcogenide nanodisks as high-index dielectric Mie nanoresonators

Monolayer transition metal dichalcogenides (TMDCs) have recently been proposed as an excitonic platform for advanced optical and electronic functionalities^1-3. However, in spite of intense research efforts, it has not been widely appreciated that TMDCs also possess a high refractive index^4,5. This characteristic opens up the possibility to utilize them to construct resonant nanoantennas based on subwavelength geometrical modes^6,7. Here, we show that nanodisks, fabricated from exfoliated multilayer WS₂, support distinct Mie resonances and anapole states⁸ that can be tuned in wavelength over the visible and near-infrared range by varying the nanodisk size and aspect ratio. As a proof of concept, we demonstrate a novel regime of light-matter interaction-anapole-exciton polaritons-which we realize within a single WS₂ nanodisk. We argue that the TMDC material anisotropy and the presence of excitons enrich traditional nanophotonics approaches based on conventional high-index materials and/or plasmonics.