Valley polarization of exciton–polaritons in monolayer WSe2 in a tunable microcavity

Abstract

Monolayer transition metal dichalcogenides, known for exhibiting strong excitonic resonances, constitute a very interesting and versatile platform for the investigation of light–matter interactions. In this work, we report on a strong coupling regime between excitons in monolayer WSe₂ and photons confined in an open, voltage-tunable dielectric microcavity. The tunability of our system allows us to extend the exciton–polariton state over a wide energy range and, in particular, to bring the excitonic component of the lower polariton mode into resonance with other excitonic transitions in monolayer WSe₂. We can retain up to 40% of initial circular polarization of the laser or loose it completely if polariton modes are brought into resonances with low energy excitonic modes.