Nonlinear interactions of dipolar excitons and polaritons in MoS2 bilayers

TL;DR

This paper demonstrates highly nonlinear excitonic and polaritonic effects in bilayer MoS2 using hybridized interlayer excitons with large oscillator strength and dipolar interactions, revealing enhanced many-body phenomena.

Contribution

It introduces the use of hybridized interlayer excitons in bilayer MoS2 to achieve and analyze highly nonlinear polaritonic effects, advancing understanding of exciton interactions in 2D materials.

Findings

Interlayer excitons exhibit 8 times higher nonlinearity than monolayer excitons.

Simultaneous excitation of hIX and intralayer excitons enhances nonlinearity.

Theoretical model introduces the concept of hole crowding to describe many-body interactions.

Abstract

Nonlinear interactions between excitons strongly coupled to light are key for accessing quantum many-body phenomena in polariton systems. Atomically-thin two-dimensional semiconductors provide an attractive platform for strong light-matter coupling owing to many controllable excitonic degrees of freedom. Among these, the recently emerged exciton hybridization opens access to unexplored excitonic species, with a promise of enhanced interactions. Here, we employ hybridized interlayer excitons (hIX) in bilayer MoS2 to achieve highly nonlinear excitonic and polaritonic effects. Such interlayer excitons possess an out-of-plane electric dipole as well as an unusually large oscillator strength allowing observation of dipolar polaritons(dipolaritons) in bilayers in optical microcavities. Compared to excitons and polaritons in MoS2 monolayers, both hIX and dipolaritons exhibit about 8 times higher nonlinearity, which is further strongly enhanced when hIX and intralayer excitons, sharing the same valence band, are excited simultaneously. This gives rise to a highly nonlinear regime which we describe theoretically by introducing a concept of hole crowding. The presented insight into many-body interactions provides new tools for accessing few-polariton quantum correlations.