Plasmon coupling in extended structures: Graphene superlattice nanoribbon arrays

TL;DR

This study investigates how plasmon interactions in extended graphene nanoribbon arrays can be tuned through structural and doping modifications, revealing complex hybrid resonances useful for infrared optical applications.

Contribution

It demonstrates the rich tunability of plasmonic resonances in graphene nanoribbon arrays with periodic doping, challenging traditional hybridization models.

Findings

Resonance energies depend on nanoribbon dimensions and doping levels.

Hybrid plasmonic resonances can occur between the energies of individual plasmons.

The system allows wide spectral tunability for infrared applications.

Abstract

Interactions between localized plasmons in proximal nanostructures is a well-studied phenomenon. Here we explore plasmon plasmon interactions in connected extended systems. Such systems can now be easily produced using graphene. Specifically we employ the finite element method to study such interactions in graphene nanoribbon arrays with a periodically modulated electrochemical potential or number of layers. We find a rich variation in the resulting plasmonic resonances depending on the dimensions and the electrochemical potentials (doping) of the nanoribbon segments and the involvement of transverse and longitudinal plasmon interactions. Unlike predictions based of the well-known "orbital hybridization model", the energies of the resulting hybrid plasmonic resonances of the extended system can lie between the energies of the plasmons of the individual components. The results demonstrate the wide range tunability of the graphene plasmons and can help to design structures with desired spectra, which can be used to enhance optical fields in the infrared region of the electromagnetic spectrum.