Exciton-polaritons in multilayer WSe 2 in a planar microcavity

Due to high binding energy and oscillator strength, excitons in thin flakes\nof transition metal dichalcogenides constitute a perfect foundation for\nrealizing a strongly coupled light-matter system. In this paper we investigate\nmono- and few-layer WSe$_2$ flakes encapsulated in hexagonal boron nitride and\nincorporated into a planar dielectric cavity. We use an open cavity design\nwhich provides tunability of the cavity mode energy by as much as 150 meV. We\nobserve a strong coupling regime between the cavity photons and the neutral\nexcitons in direct-bandgap monolayer WSe$_2$, as well as in few-layer WSe$_2$\nflakes exhibiting indirect bandgap. We discuss the dependence of the exciton's\noscillator strength and resonance linewidth on the number of layers and predict\nthe exciton-photon coupling strength.\n