Signatures of dark excitons in exciton-polariton optics of transition metal dichalcogenides

Abstract

Integrating 2D materials into high-quality optical microcavities opens the door to fascinating many-particle phenomena including the formation of exciton-polaritons. These are hybrid quasi-particles inheriting properties of both the constituent photons and excitons. In this work, we investigate the so-far overlooked impact of dark excitons on the momentum-resolved absorption spectra of hBN-encapsulated WSe${}_2$ and MoSe${}_2$ monolayers in the strong-coupling regime. In particular, thanks to the efficient phonon-mediated scattering of polaritons into energetically lower dark exciton states, the absorption of the lower polariton branch in WSe${}_2$ is much higher than in MoSe${}_2$. It shows unique step-like increases in the momentum-resolved profile indicating opening of specific scattering channels. We study how different externally accessible quantities, such as temperature or mirror reflectance, change the optical response of polaritons. Our study contributes to an improved microscopic understanding of exciton-polaritons and their interaction with phonons, potentially suggesting experiments that could determine the energy of dark exciton states via momentum-resolved polariton absorption.

10 pages, 5 figures

References in corpus (14)

• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Tightly bound excitons in monolayer WSe2
• Strong light-matter coupling in two-dimensional atomic crystals
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Intrinsic Transport Properties of Electrons and Holes in Monolayer Transition Metal Dichalcogenides
• Dark excitons in transition metal dichalcogenides
• Tunable Phases of Moiré Excitons in van der Waals Heterostructures
• Momentum-resolved observation of exciton formation dynamics in monolayer WS${}_2$
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Intrinsic Lifetime of Higher Excitonic States in Tungsten Diselenide Monolayers
• Twist Angle Tuning of Moiré Exciton Polaritons in van der Waals Heterostructures
• Dark exciton-exciton annihilation in monolayer WSe${}_2$
• Microscopic modelling of exciton-polariton diffusion coefficients in atomically thin semiconductors
• Phonon signatures in spectra of exciton polaritons in transition metal dichalcogenides

Cited by in corpus (5)

• Circumventing the polariton bottleneck via dark excitons in 2D semiconductors
• Magneto-Optics of Anisotropic Exciton Polaritons in Two-Dimensional Perovskites
• Two dimensional semiconductors: optical and electronic properties
• Theory of phonon sidebands in the absorption spectra of moiré exciton-polaritons
• Polariton transport in 2D semiconductors: Phonon-mediated transitions between ballistic, superdiffusive and exciton-limited regimes