Tailoring optical response of a hybrid comprising a quantum dimer emitter strongly coupled to a metal nanoparticle

TL;DR

This paper theoretically investigates a hybrid system of a quantum dimer coupled to a metal nanoparticle, revealing novel optical effects such as bistability, hysteresis, and tunable Fano-like absorption spectra influenced by detuning and input power.

Contribution

It introduces a comprehensive theoretical analysis of exciton-plasmon hybridization effects, including nonlinear optical phenomena and spectral shaping in a quantum emitter-metal nanoparticle system.

Findings

Optical bistability and hysteresis in the hybrid system.

Enhanced excitation and reduced saturation field due to exciton-plasmon coupling.

Tunable Fano-like absorption spectra dependent on detuning and input power.

Abstract

We study theoretically the optical response of a nanohybrid comprising a symmetric quantum dimer emitter coupled to a metal nanoparticle (MNP). The interactions between the exitonic transitions in the dimer and the plasmons in the MNP lead to novel effects in the composite's input-output characteristics for the light intensity and the absorption spectrum, which we study in the linear and nonlinear regimes. We fnd that the exciton-plasmon hybridization leads to optical bistability and hysteresis for the one-exciton transition and enhancement of excitation for the two-exciton transition. The latter leads to a signifcant decrease of the field strength needed to saturate the system. In the linear regime, the absortion spectrum has a dispersive (Fano-like) line shape. The spectral position and shape of this spectrum depend on the detuning of the dimer's one-exciton resonance relative to the plasmon resonance. Upon increasing the applied field intensity to the nonlinear regime, the Fano-like singularities in the absorption spectra are smeared and they disappear due to the saturation of the dimer, which leads to the MNP dominating the spectrum. The above effects, for which we provide physical explanations, allow one to tailor the Fano-like shape of the absorption spectrum, by changing either the detuning or the input power.