Exciton polaritons in two-dimensional dichalcogenide layers placed in a planar microcavity: Tunable interaction between two Bose-Einstein condensates

Abstract

Exciton-polariton modes arising from interaction between bound excitons in monolayer thin semiconductor sheets and photons in a Fabry-Perot microcavity are considered theoretically. We calculate the dispersion curves, mode lifetimes, Rabi splitting, and Hopfield coefficients of these structures for two nearly 2D semiconductor materials, MoS2 and WS2, and suggest that they are interesting for studying the rich physics associated with the Bose-Einstein condensation of exciton-polaritons. The large exciton binding energy and dipole allowed exciton transitions, in addition to the relatively easily controllable distance between the semiconductor sheets are the advantages of this system in comparison with traditional GaAs or CdTe based semiconductor microcavities. In particular, in order to mimic the rich physical properties of the quantum degenerate mixture of two bosonic species of dilute atomic gases with tunable inter-species interaction , we put forward a structure containing two semiconductor sheets separated by some atomic-scale distance (l) using a nearly 2D dielectric (e.g. h-BN), which offers the possibility of tuning the interaction between two exciton-polariton Bose-Enstein condensates. We show that the dynamics of this novel structure are ruled by two coupled Gross-Pitaevskii equations with the coupling parameter ∼ l −1 .

Near-field relaxation of a quantum emitter to two-dimensional semiconductors: Surface dissipation and exciton polaritons

“…We trace this effect to the near-field energy transfer from the QE to the surface exciton polariton. In addition to implications for energy transfer applications, such as photodetectors [19], photovoltaic [20] and light emitting devices [21][22][23], our results show that low-dimensional materials can be used to study polaritons and exciton-photon coupling phenomena without requiring a microcavity [24]. Herein we demonstrate that MoS 2 monolayers can support surface exciton polariton modes and their influence on the optical properties of QEs is substantial.…”

“…1 we present the real and imaginary parts of the surface conductivity for different values of the damping parameters, γ A and γ B [24]. The damping parameters, γ A and γ B , are connected with the quality of the MoS 2 layer at different temperatures, and for that reason we choose to investigate a broader spectrum of parameters to account for the different mechanism of losses [37].…”

“…A systematic analysis is needed to account for the spectral and distance dependence of the QE-TMD layer interaction. Here we focus on material parameters describing the semiconducting behavior of MoS 2 , through the exciton energies and damping parameters [17,24,32].…”

Excitonic effects in the optical properties of 2D materials:an equation of motion approach

“…The application of these systems to opto-electronics, including photo-detectors, will launch a new set of devices in this area. Another possibility that these 2D materials may provide is the engineering Bose-Einstein condensation of excitons when a TMDC is put inside an optical cavity [26].…”

Excitons in atomically thin transition-metal dichalcogenides

“…The integration of the TMD MLs in optical cavities highlights this aspect. Indeed, the strongcoupling regime has been demonstrated, where excitons and photons mix to create hybrid quasiparticles, exciton polaritons Flatten et al, 2016;Liu et al, 2015b;Lundt et al, 2016;Sidler et al, 2016;Vasilevskiy et al, 2015). The discussion above highlights the complex challenges for interpreting for example photoluminescence emission times measured in experiments in terms of intrinsic decay rates, effective radiative lifetimes and non-radiative channels, for example.…”