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

Longlong Yang, Xin Xie, Jingnan Yang, Mengfei Xue, Shiyao Wu, Shan Xiao, Feilong Song, Jianchen Dang, Sibai Sun, Zhanchun Zuo, Jianing Chen, Yuan Huang, Xingjiang Zhou, Kuijuan Jin, Can Wang, Xiulai Xu

Published 2022-03-03Version 1

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.