Extraordinary nonlinear plasmonics in graphene nanoislands

TL;DR

This paper demonstrates that graphene nanoislands exhibit highly tunable nonlinear optical responses, surpassing metal nanoparticles, making them promising for advanced nonlinear nanodevices.

Contribution

It reveals that electrically tunable graphene nanoislands have nonlinear polarizabilities vastly exceeding those of similar-sized metal nanoparticles.

Findings

Graphene nanoislands' nonlinear polarizabilities can be electrically tuned.

Nanoislands exhibit nonlinear responses over visible and near-infrared.

Quantum simulations confirm graphene's potential for nonlinear nanodevices.

Abstract

Nonlinear optical processes rely on the intrinsically weak interactions between photons enabled by their coupling with matter. Unfortunately, many applications in nonlinear optics are severely hindered by the small response of conventional materials. Metallic nanostructures partially alleviate this situation, as the large light enhancement associated with their localized plasmons amplifies their nonlinear response to record high levels. Graphene hosts long-lived, electrically tunable plasmons that also interact strongly with light. Here we show that the nonlinear polarizabilities of graphene nanoislands can be electrically tuned to surpass by several orders of magnitude those of metal nanoparticles of similar size. This extraordinary behavior extends over the visible and near-infrared for islands consisting of hundreds of carbon atoms doped with moderate carrier densities. Our quantum-mechanical simulations of the plasmon-enhanced optical response of nanographene reveal this material as an ideal platform for the development of electrically tunable nonlinear optical nanodevices.