Transition to strong coupling regime in hybrid plasmonic systems: Exciton-induced transparency and Fano interference

TL;DR

This paper develops a microscopic model to analyze the transition to strong coupling in hybrid plasmonic systems, highlighting the roles of exciton-induced transparency and Fano interference in shaping scattering spectra.

Contribution

It introduces a detailed model explaining how near-field coupling and Fano interference influence spectral features during the strong coupling transition.

Findings

Near-field coupling causes exciton-induced transparency before strong coupling.

Fano interference can invert spectral asymmetry in scattering spectra.

The model explains experimental observations of spectral shape changes.

Abstract

We present a microscopic model describing the transition to strong coupling regime for an emitter resonantly coupled to a surface plasmon in a metal-dielectric structure. We demonstrate that the shape of scattering spectra is determined by an interplay of two distinct mechanisms. First is the near-field coupling between the emitter and the plasmon mode which underpins energy exchange between the system components and gives rise to exciton-induced transparency minimum in scattering spectra prior the transition to strong coupling regime. The second mechanism is Fano interference between the plasmon dipole and the plasmon-induced emitter's dipole as the system interacts with the radiation field. We show that the Fano interference can strongly affect the overall shape of scattering spectra, leading to the inversion of spectral asymmetry that was recently reported in the experiment.