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

M. Król, K. Lekenta, R. Mirek, K. Łempicka, D. Stephan, K. Nogajewski, M. R. Molas, A. Babiński, M. Potemski, J. Szczytko, B. Piętka

Published 2018-09-25Version 1

Monolayer transition metal dichalcogenides, known for exhibiting strong excitonic resonances, constitute a very interesting and versatile platform for 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. With selective excitation of spin-polarized exciton-polaritons we demonstrate the valley polarization when the polaritons from the lower branch come into resonance with a bright trion state in monolayer WSe2 and valley depolarization when they are in resonance with a dark trion state.