Infrared hyperbolic metasurface based on nanostructured van der Waals materials

TL;DR

This paper demonstrates a mid-infrared hyperbolic metasurface created by nanostructuring hexagonal boron nitride, enabling visualization of hyperbolic polaritons and opening new avenues for compact photonic devices.

Contribution

It introduces a novel hyperbolic metasurface based on nanostructured van der Waals materials and visualizes polariton wavefronts using infrared nanoimaging.

Findings

Visualization of anomalous wavefronts of polaritons

Nanostructured van der Waals materials support hyperbolic dispersion

Potential for compact infrared photonic devices

Abstract

Metasurfaces with strongly anisotropic optical properties can support deep subwavelength-scale confined electromagnetic waves (polaritons) that promise opportunities for controlling light in photonic and optoelectronic applications. We develop a mid-infrared hyperbolic metasurface by nanostructuring a thin layer of hexagonal boron nitride supporting deep subwavelength-scale phonon polaritons that propagate with in-plane hyperbolic dispersion. By applying an infrared nanoimaging technique, we visualize the concave (anomalous) wavefronts of a diverging polariton beam, which represent a landmark feature of hyperbolic polaritons. The results illustrate how near-field microscopy can be applied to reveal the exotic wavefronts of polaritons in anisotropic materials, and demonstrate that nanostructured van der Waals materials can form a highly variable and compact platform for hyperbolic infrared metasurface devices and circuits.