Greatly Enhanced Plasmon–Exciton Coupling in Si/WS₂/Au Nanocavities

Abstract

A strong light–matter interaction is highly desirable from the viewpoint of both fundamental research and practical application. Here, we propose a dielectric–metal hybrid nanocavity composed of a silicon (Si) nanoparticle and a thin gold (Au) film and investigate numerically and experimentally the coupling between the plasmons supported by the nanocavity and the excitons in an embedded tungsten disulfide (WS2) monolayer. When a Si/WS2/Au nanocavity is excited by the surface plasmon polariton generated on the surface of the Au film, greatly enhanced plasmon–exciton coupling originating from the hybridization of the surface plasmon polariton, the mirror-image-induced magnetic dipole, and the exciton modes is clearly revealed in the angle- or size-resolved scattering spectra. A Rabi splitting as large as ∼240 meV is extracted by fitting the experimental data with a coupled harmonic oscillator model containing three oscillators. Our findings open new horizons for constructing nanoscale photonic devices by exploiting dielectric–metal hybrid nanocavities.

Optical Introduction and Manipulation of Plasmon–Exciton–Trion Coupling in a Si/WS2/Au Nanocavity

“…Previously, the criterion for the strong coupling of three elementary excitations has been discussed. , In this work, it can be expressed as follows: …”

“…In this work, the numerical simulations were performed by using the finite-difference time-domain (FDTD) technique. The dielectric constants of Au and Si were taken from Johnson and Christy and from Palik, respectively. The dielectric constant of the WS 2 monolayer was obtained from the previous literature .…”

“…Moreover, trions consisting of two electrons and one hole can be generated at high laser powers, ,, offering us the opportunity for studying plasmon–trion and even plasmon–exciton–trion coupling in the hybrid nanocavity. Recently, strong coupling among three excitations has become the focus of many studies in light–matter interaction. , In most cases, the strong coupling occurs among two optical/plasmon modes and one exciton resonance. − In comparison, one plasmon mode and two exciton resonances are involved in plasmon–exciton–trion coupling, which enables the energy exchange between excitons and trions mediated by the plasmon mode. Previously, plasmon–exciton–trion coupling was observed in a WS 2 monolayer coupled with an silver nanoprism at a low temperature of 6.0 K .…”

Entanglement generation by strong coupling between surface lattice resonance and exciton in an Al nanoarray coated WS2 quantum emitter

“…Xiaoqi Shi 1,2 , Zhihang Wang 1,2 , Jiamin Xiao 1,2 , Lingyao Li 1,2 , Shibo Wei 1,2 , Zhicheng Guo 1 , Yi Wang 1,2 , Wenxin Wang 1,2* ()…”

Resonance Coupling in Si@WS2Core-Ω Shell Nanostructure

“…Hence, the Si NS is often directly placed on the TMDCs NMB/Metal (Au, Ag, etc.) substrate to investigate the Fano resonance [ 31 ], the directional scattering enhancement [ 32 ] and so on. In the above nanostructures, the contact surface between the Si NS and the TMDCs NMB is small, resulting in a weak resonance coupling.…”