Edge-oriented and steerable hyperbolic polaritons in anisotropic van der Waals nanocavities

Zhigao Dai, Guangwei Hu, Guangyuan Si, Qingdong Ou, Qing Zhang, Sivacarendran Balendhran, Fahmida Rahman, Bao Yue Zhang, Jian Zhen Ou, Guogang Li, Andrea Alù, Cheng Wei Qiu, Qiaoliang Bao

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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-MoO3 and V2O5, 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-MoO3 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-MoO3 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.

Original languageEnglish
Article number6086
Number of pages8
JournalNature Communications
Issue number1
Publication statusPublished - Dec 2020

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