Highly confined low-loss plasmons in graphene-boron nitride heterostructures

TL;DR

This paper demonstrates highly confined, low-loss graphene plasmons in heterostructures with boron nitride, revealing low damping mechanisms crucial for advanced nano-optoelectronic applications.

Contribution

It provides the first real-space imaging and analysis of low-damping, highly confined plasmons in graphene-hBN heterostructures, identifying intrinsic phonons and dielectric losses as main damping channels.

Findings

Unprecedented low plasmon damping observed

Strong field confinement achieved in heterostructures

Main damping channels are intrinsic phonons and dielectric losses

Abstract

Graphene plasmons were predicted to possess ultra-strong field confinement and very low damping at the same time, enabling new classes of devices for deep subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. While all of these great prospects require low damping, thus far strong plasmon damping was observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this letter we exploit near-field microscopy to image propagating plasmons in high quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine dispersion and particularly plasmon damping in real space. We find unprecedented low plasmon damping combined with strong field confinement, and identify the main damping channels as intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key for the development of graphene nano-photonic and nano-optoelectronic devices.