Collective Mie Exciton-Polaritons in an Atomically Thin Semiconductor

Abstract

Optically induced Mie resonances in dielectric nanoantennas feature low dissipative losses and a large resonant enhancement of both the electric and magnetic fields. They offer an alternative platform to plasmonic resonances to study light–matter interactions from weak to strong coupling regimes. Here, we experimentally demonstrate the strong coupling of bright excitons in monolayer WS2 with Mie surface lattice resonances (Mie-SLRs). We resolve both the electric and magnetic Mie-SLRs of a Si nanoparticle array in angular dispersion measurements. At the zero detuning condition, the dispersion of electric Mie-SLRs (e-SLRs) exhibits a clear anti-crossing and a Rabi splitting of 32 meV between the upper and lower polariton bands. The magnetic Mie-SLRs (m-SLRs) nearly cross the energy band of the excitons. These results suggest that the field of m-SLRs is dominated by out-of-plane components that do not efficiently couple with the in-plane excitonic dipoles of the monolayer WS2. In contrast, e-SLRs in dielectric nanoparticle arrays with relatively high quality factors (Q ∼ 120) facilitate the formation of collective Mie exciton-polaritons and may allow the development of novel polaritonic devices, which can tailor the optoelectronic properties of atomically thin two-dimensional semiconductors.