Kerr nonlinearity and plasmonic bistability in graphene nanoribbons

TL;DR

This paper investigates how Kerr nonlinearities influence plasmonic behavior in graphene nanoribbons, revealing resonance shifts and bistability phenomena that could impact future nanophotonic applications.

Contribution

It introduces a semiclassical model for Kerr nonlinearities in graphene nanostructures and demonstrates their effects on resonance shifts and bistability, supported by numerical simulations.

Findings

Resonance shifts are accurately approximated by a simple analytical model.

Nonlinearities are significantly enhanced near plasmonic resonances due to field inhomogeneity.

Plasmonic bistability occurs at frequencies redshifted from the linear resonance.

Abstract

We theoretically examine the role of Kerr nonlinearities for graphene plasmonics in nanostructures, specifically in nanoribbons. The nonlinear Kerr interaction is included semiclassically in the intraband approximation. The resulting electromagnetic problem is solved numerically by self-consistent iteration with linear steps using a real-space discretization. We derive a simple approximation for the resonance shifts in general graphene nanostructures, and obtain excellent agreement with numerics for moderately high field strengths. Near plasmonic resonances the nonlinearities are strongly enhanced due to field enhancement, and the total nonlinearity is significantly affected by the field inhomogeneity of the plasmonic excitation. Finally, we discuss the emergence of a plasmonic bistability which exists for frequencies redshifted relative to the linear resonance. Our results offer new insights into the role of nonlinear interaction in nanostructured graphene and paves the way for experimental investigation.