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The advent of layered materials has unveiled new opportunities for tailoring electromagnetic waves at the subwavelength scale, particularly through the study of polaritons, a hybrid light–matter excitation. In this context, twist-optics, which investigates the optical properties of twisted stacks of van der Waals (vdW) layered specimens, has emerged as a powerful tool. Here, we explore the tunability of phonon polaritons in α-V2O5via interlayer twisting using scanning nano-infrared (IR) imaging. We show that the polaritonic response can be finely adjusted by varying their interlayer electromagnetic coupling, allowing for precise control over the propagation direction and phase transition from open unidirectional iso-frequency contours to closed elliptic geometries. Our experimental results, in conjugate with theoretical modeling, reveal the mechanisms underpinning this tunability, highlighting the role of twist-induced nano-light modifications for advanced nanophotonic control at the nanoscale.
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This content will become publicly available on August 22, 2027
Tunable Polariton Canalization in Natural Van Der Waals Oxide
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 α‐V2O5, a layered compound with a highly anisotropic permittivity tensor. We show unidirectional Poynting‐vector propagation of polaritons in α‐V2O5without 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 α‐V2O5holds great promise for on‐demand light canalization and control at the nanoscale.
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- Award ID(s):
- 2219003
- PAR ID:
- 10707974
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Optical Materials
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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