Hybridization of the A- and B‑Exciton in a WS2 Monolayer Mediated by the Transverse Electric Polarized Wave Supported by a Si3N4/Ag Heterostructure

Realizing and manipulating strong light–matter coupling in two-dimensional monolayer semiconductors is important in the research of cavity quantum electrodynamics and the development of photonic/plasmonic devices. Here, we investigate the coupling between the transverse-electric (TE) polarized wave supported by a Si3N4/Ag heterostructure and the two excitons in a WS2 monolayer (i.e., the A- and B-excitons) attached on such a heterostructure. It is found that the dissipation rate of the TE wave can be modified by simply varying the thickness of the Ag film. By appropriately designing the thickness of the Ag film, the strong coupling between the TE wave and the two excitons in the WS2 monolayer can be simultaneously realized, leading to hybridization of the two excitons. We numerically simulate the angle-resolved reflection spectra for the WS2/Si3N4/Ag heterostructure and reveal hybridization of the two excitons mediated by the TE wave. In experiments, we introduce Au nanorods as scatters for the TE wave, which enhance the in-plane electric field and achieve stronger photon–exciton coupling. We experimentally measured the angled-resolved scattering spectra for an Au nanorod placed on the WS2/Si3N4/Ag heterostructure and demonstrated the strong coupling between the TE wave and the two excitons, which results in the hybridization of the two excitons. Our findings open horizons for realizing and manipulating strong light–matter interaction in two-dimensional materials and pave the way for the construction of photonic/plasmonic devices by exploiting dielectric–metal heterostructure.