Strong light-matter interactions between gap plasmons and two-dimensional excitons at ambient condition in a deterministic way

TL;DR

This paper demonstrates a robust strong exciton-plasmon coupling in 2D MoS2 layers at room temperature using a large-area nanocavity, enabling potential quantum-electrodynamics applications.

Contribution

The study introduces a new method for achieving strong coupling between gap plasmons and 2D excitons over large areas at ambient conditions.

Findings

Achieved strong exciton-plasmon coupling with large-area MoS2 layers.

Reduced the effective exciton number contributing to the coupling.

Demonstrated room-temperature strong coupling with few excitons.

Abstract

Strong exciton-plasmon interaction between the layered two-dimensional (2D) semiconductors and gap plasmons shows a great potential to implement cavity quantum-electrodynamics in ambient condition. However, achieving a robust plasmon-exciton coupling with nanocavity is still very challenging, because the layer area is usually small with conventional approaches. Here, we report on a robust strong exciton-plasmon coupling between the gap mode of bowtie and the excitons in MoS$_2$ layers with gold-assisted mechanical exfoliation and the nondestructive wet transfer techniques for large-area layer. Benefiting from the ultrasmall mode volume and strong in-plane field, the estimated effective exciton number contributing to the coupling is largely reduced. With a corrected exciton transition dipole moment, the exciton numbers are extracted with 40 for the case of monolayer and 48 for 8 layers. Our work paves a way to realize the strong coupling with 2D materials with few excitons at room temperature.