Plasmon Confinement by Carrier Density Modulation in Graphene

TL;DR

This study demonstrates that carrier density modulation in graphene can confine plasmon resonances, with terahertz spectroscopy revealing localized plasmon modes in periodically patterned micro-ribbons.

Contribution

It introduces a method to confine plasmons in graphene through periodic carrier density modulation, advancing plasmonic control in 2D materials.

Findings

Two distinct plasmon modes localized in different ribbon arrays.

Plasmons are selectively excited depending on the Fermi energy.

Carrier density modulation enables plasmon confinement in graphene.

Abstract

We investigate plasmon resonances in graphene with periodic carrier density modulation. The period is 8 um, and each period consists of 1.7- and 6.3-um-wide ribbons with different density. Using terahertz spectroscopy, we show two plasmon modes with their electric field mostly localized in the 1.7- or 6.3-um-wide ribbon arrays. We also show that plasmons are excited only in one of the micro-ribbon arrays when the Fermi energy of the other micro-ribbon array is set close to the charge neutrality point. These results indicate that plasmons can be confined by the carrier density modulation.