Modulating the Temporal Dynamics of Nonlinear Ultrafast Plasmon Resonances

Nonlinear plasmon modes (NLPs) supported by metallic nanoparticles play a vital role in enhanced nonlinear optics, high-resolution optical imaging and advanced spectroscopy applications [1]. However, the ultrashort lifetime of these intense nonlinear fields inhibits their effective use in the vast applications of quantum plasmonics. These NLPs formulate through the spatial convolution of fundamental plasmon modes (FM) and decay shortly within 10 fs [2]. FM, being a constituent part, contributes to the intensity and spatiotemporal dynamics of nonlinear plasmonic signal. To acquire pure nonlinear effects, its spectral and temporal independence from the FM is of significant importance. In this paper, we demonstrate the lifetime enhancement of second harmonic (SH) plasmon mode, supported by Au nanoparticle (AuNP), through the resonant coupling with long-lived quantum emitter (QE) (Fig. 1(a) inset) [3]. We utilize coupled harmonic oscillator model and the total Hamiltonian of the system given in Eq.1 consists of eigen energies of plasmon modes (
$\alpha_{j}$
) and QE, interaction term with coupling strength (
$\kappa$
), interaction of incident light (
$\omega$
) and the convolution of FM along with nonlinear susceptibilty
$\chi^{(2)}$
.