Exciton polaritons in two-dimensional semiconductors

Atomically thin crystals of transition metal dichalcogenides (TMDs) host excitons with strong binding energies and sizable light-matter interactions. Coupled to optical cavities, monolayer TMDs routinely reach the regime of strong light-matter coupling, where excitons and photons admix coherently to form quasiparticles known as polaritons up to room temperature. We explore the two-dimensional nature of TMD polaritons with cavity-assisted hyperspectral imaging. Using extended WS2 monolayers, we establish the regime of strong