Fano plasmonics goes nonlinear

TL;DR

This paper explores how Fano resonances in plasmonic nano-antennas can significantly enhance second harmonic generation, combining rigorous simulations with a simple analytical model to understand the nonlinear optical response.

Contribution

It introduces a comprehensive Maxwell-hydrodynamics simulation approach and a coupled oscillator model to analyze nonlinear Fano plasmonics, highlighting enhancement mechanisms.

Findings

Noticeable enhancement of second harmonic efficiency at antisymmetric mode

Numerical simulations confirm the role of Fano resonances in nonlinear enhancement

Analytical model supports the simulation results

Abstract

We investigate the process of the second harmonic generation by plasmonic nano-antennas that exhibit Fano-like resonances. A rigorous fully vectorial Maxwell-hydrodynamics approach is employed to directly calculate the second order susceptibilities as function of the pump frequency, considering a periodic array of nanodolmens comprised of three Au nanorods. The results of the numerical simulations demonstrate noticeable enhancement of the second harmonic efficiency by the antisymmetric mode. Additionally, a simple analytical model based on two coupled nonlinear oscillators is proposed. It is shown that the second order optical response can be significantly enhanced at the frequency of the antisymmetric normal mode thus supporting our numerical results.