Edge-oriented and steerable hyperbolic polaritons in anisotropic van der Waals nanocavities.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33257664.
- Also identified by DOI 10.1038/s41467-020-19913-4 and PMC identifier 7705012.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Highly confined and low-loss polaritons are known to propagate isotropically over graphene and hexagonal boron nitride in the plane, leaving limited degrees of freedom in manipulating light at the nanoscale. The emerging family of biaxial van der Waals materials, such as α-MoO<sub>3</sub> and V<sub>2</sub>O<sub>5</sub>, support exotic polariton propagation, as their auxiliary optical axis is in the plane. Here, exploiting this strong in-plane anisotropy, we report edge-tailored hyperbolic polaritons in patterned α-MoO<sub>3</sub> nanocavities via real-space nanoimaging. We find that the angle between the edge orientation and the crystallographic direction significantly affects the optical response, and can serve as a key tuning parameter in tailoring the polaritonic patterns. By shaping α-MoO<sub>3</sub> nanocavities with different geometries, we observe edge-oriented and steerable hyperbolic polaritons as well as forbidden zones where the polaritons detour. The lifetime and figure of merit of the hyperbolic polaritons can be regulated by the edge aspect ratio of nanocavity.