Terahertz and mid-infrared plasmons in three-dimensional nanoporous graphene

Fausto D’Apuzzo,Yoshikazu Ito,Flavio Giorgianni,Mariangela Cestelli Guidi,Alba R Piacenti,Ulrich Schade,Augusto Marcelli,Stefano Lupi,Mingwei Chen,Marta Autore

doi:10.1038/ncomms14885

Abstract

Two-dimensional (2D) graphene emerged as an outstanding material for plasmonic and photonic applications due to its charge-density tunability, high electron mobility, optical transparency and mechanical flexibility. Recently, novel fabrication processes have realised a three-dimensional (3D) nanoporous configuration of high-quality monolayer graphene which provides a third dimension to this material. In this work, we investigate the optical behaviour of nanoporous graphene by means of terahertz and infrared spectroscopy. We reveal the presence of intrinsic 2D Dirac plasmons in 3D nanoporous graphene disclosing strong plasmonic absorptions tunable from terahertz to mid-infrared via controllable doping level and porosity. In the far-field the spectral width of these absorptions is large enough to cover most of the mid-Infrared fingerprint region with a single plasmon excitation. The enhanced surface area of nanoporous structures combined with their broad band plasmon absorption could pave the way for novel and competitive nanoporous-graphene based plasmonic-sensors.

Highlights

Two-dimensional (2D) graphene emerged as an outstanding material for plasmonic and photonic applications due to its charge-density tunability, high electron mobility, optical transparency and mechanical flexibility
We show the presence of intrinsic 2D Dirac plasmons in 3D nanoporous graphene (NPG) disclosing their behaviour with controllable doping level and tunable porosity
The samples here investigated were well characterized through photoemission (PES), Raman spectroscopy, and transport measurements[13]

Summary

Introduction

Two-dimensional (2D) graphene emerged as an outstanding material for plasmonic and photonic applications due to its charge-density tunability, high electron mobility, optical transparency and mechanical flexibility. The low dimensionality of graphene induces an extreme compression of plasmons[7], especially at mid-infrared (MIR) and terahertz (THz) frequencies, which allows their nanoscale confinement, as it has been theoretically predicted and further experimentally demonstrated[8,9] With these motivations, many graphene micro- and nano-structures have been proposed and realized in the last few years, combining different shapes and sizes[5,10,11], multi-layer systems, different substrates and hybrid devices, including active configurations for plasmonic control through optical[12] and electrical pulses[4,8,9]. By taking into account the enhanced surface area of these nanoporous structures[18] in combination with their tunable plasmons, this work paves the way for innovative graphenebased plasmonic-sensors

Methods

Results

Conclusion