Coupling-Enhanced Broadband Mid-Infrared Light Absorption in Graphene Plasmonic Nanostructures

TL;DR

This paper demonstrates that engineering coupling among graphene nanostructures enhances light interaction and broadens spectral response, enabling efficient mid-infrared absorption for sensing and communication applications.

Contribution

It introduces a novel coupling engineering approach in graphene nanostructures to simultaneously enhance and broaden mid-infrared plasmonic resonances.

Findings

Achieved 5-7% extinction across 8-14 μm range

Demonstrated coupling-induced spectral broadening

Potential applications in infrared sensing and communication

Abstract

Plasmons in graphene nanostructures show great promise for mid-infrared applications ranging from a few to tens of microns. However, mid-infrared plasmonic resonances in graphene nanostructures are usually weak and narrow-banded, limiting their potential in light manipulation and detection. Here we investigate the coupling among graphene plasmonic nanostructures and further show that by engineering the coupling, enhancement of light-graphene interaction strength and broadening of spectral width can be achieved simultaneously. Leveraging the concept of coupling, we demonstrate a hybrid 2-layer graphene nanoribbon array which shows 5 to 7% extinction within the entire 8 to 14 {\mu}m (~700 to 1250 cm-1) wavelength range, covering one of the important atmosphere "infrared transmission windows". Such coupled hybrid graphene plasmonic nanostructures may find applications in infrared sensing and free-space communications.