Tunable Polariton Canalization in Natural van der Waals Oxide

TL;DR

This study demonstrates tunable, unidirectional polariton canalization in alpha-V2O5, a natural layered oxide, enabling advanced nanoscale light control without complex fabrication.

Contribution

It reveals in-plane hyperbolicity and tunable polariton canalization in alpha-V2O5 through infrared nano-imaging and theoretical modeling, avoiding complex device modifications.

Findings

Unidirectional Poynting-vector polariton propagation in alpha-V2O5.

Dispersion contour tunable by incident light frequency.

Permittivity phase diagram for tailoring polaritonic wavefronts.

Abstract

Hyperbolic phonon polaritons (HPPs) are coupled oscillations of anisotropic lattice vibrations and electromagnetic fields that confine the latter to the nanoscale, enabling novel nano-polaritonic devices. While HPPs have been identified in multiple layered materials, achieving advanced control and manipulation - particularly polariton canalization for unidirectional energy flow - often necessitates complex device fabrications or crystal modifications. Here we visualize and elucidate the properties of in-plane hyperbolicity in alpha-V2O5, a layered compound with a highly anisotropic permittivity tensor. We show unidirectional Poynting-vector propagation of polaritons in alpha-V2O5 without additional treatments. Combined with theoretical modeling, our infrared nano-imaging studies unveil a novel form of polariton canalization, with its dispersion contour continuously tunable by the incident light frequency. Additionally, we provide a theoretically calculated permittivity phase diagram for tailoring polaritonic wavefronts. These findings suggest that the metal-oxide alpha-V2O5 holds great promise for on-demand light canalization and control at the nanoscale.