Relative efficiency of polariton emission in two-dimensional materials

TL;DR

This study explores how polaritons are emitted and propagate in hexagonal boron nitride, revealing that scanning tips are highly efficient emitters, which could advance polaritonic device development.

Contribution

It demonstrates that scanning tips can serve as highly efficient polariton emitters in 2D materials, outperforming other common emission methods.

Findings

Scanning tips are superior polariton launchers.

Multiple emission mechanisms including edges, nanostructures, and defects.

Insights into polariton emission efficiency for device applications.

Abstract

We investigated emission and propagation of polaritons in a two dimensional van der Waals material hexagonal boron nitride (hBN). Our specific emphasis in this work is on hyperbolic phonon polariton emission that we investigated by means of scattering-type scanning near-field optical microscopy. Real-space nano-images detail how the polaritons are launched in several common arrangements including: light scattering by the edges of the crystal, metallic nanostructures deposited on the surface of hBN crystals, as well as random defects and impurities. Notably, the scanned tip of the near-field microscope is itself an efficient polariton launcher. Our analysis reveals that the scanning tips are superior to other types of emitters we have investigated. Furthermore, the study of polariton emission and emission efficiency may provide insights for development of polaritonic devices and for fundamental studies of collective modes in other van der Waals materials.