Room-temperature exciton-polaritons with two-dimensional WS2

TL;DR

This study demonstrates the formation of well-resolved exciton-polaritons at room temperature in monolayer WS2 coupled to a Fabry-Perot cavity, with significant Rabi splitting, paving the way for ambient-temperature polariton-based devices.

Contribution

The paper reports the first clear observation of room-temperature exciton-polaritons in monolayer WS2 with large Rabi splitting, using an open cavity and transfer matrix modeling.

Findings

Achieved unambiguous exciton-polariton eigenstates at room temperature.

Maximal Rabi splitting of 70 meV exceeds exciton linewidth.

Data well described by a transfer matrix model for large linewidth regimes.

Abstract

Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensationand superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS$_2$ coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of $\hbar \Omega_{\rm{Rabi}} = 70$ meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications.