Reconfigurable Mid-Infrared Hyperbolic Metasurfaces using Phase-Change Materials

TL;DR

This paper demonstrates a reconfigurable hyperbolic metasurface using phase-change materials, enabling dynamic control of light propagation at the nanoscale for advanced optical applications.

Contribution

It introduces a novel heterostructure combining hexagonal boron nitride and vanadium dioxide to achieve tunable hyperbolic phonon polaritons with significant wavelength shifts.

Findings

Wavelength of HPhPs changed by a factor of 1.6

Enabled in-plane launching, refraction, and reflection of HPhPs

Framework for designing reconfigurable optical functionalities

Abstract

Metasurfaces offer the potential to control light propagation at the nanoscale for applications in both free-space and surface-confined geometries. Existing metasurfaces frequently utilize metallic polaritonic elements with high absorption losses, and/or fixed geometrical designs that serve a single function. Here we overcome these limitations by demonstrating a reconfigurable hyperbolic metasurface comprising of a heterostructure of isotopically enriched hexagonal boron nitride (hBN) in direct contact with the phase-change material (PCM) vanadium dioxide (VO2). Spatially localized metallic and dielectric domains in VO2 change the wavelength of the hyperbolic phonon polaritons (HPhPs) supported in hBN by a factor 1.6 at 1450cm-1. This induces in-plane launching, refraction and reflection of HPhPs in the hBN, proving reconfigurable control of in-plane HPhP propagation at the nanoscale15. These results exemplify a generalizable framework based on combining hyperbolic media and PCMs in order to design optical functionalities such as resonant cavities, beam steering, waveguiding and focusing with nanometric control.