Hybridized hyperbolic surface phonon polaritons at α-MoO3 and polar dielectric interfaces

Qing Zhang, Qingdong Ou, Guangwei Hu, Jingying Liu, Zhigao Dai, Michael S. Fuhrer, Qiaoliang Bao, Cheng-Wei Qiu

Research output: Contribution to journalArticleResearchpeer-review

79 Citations (Scopus)


Surface phonon polaritons (SPhPs) in polar dielectrics offer new opportunities for infrared nanophotonics. However, bulk SPhPs inherently propagate isotropically with limited photon confinement, and how to collectively realize ultralarge confinement, in-plane hyperbolicity, and unidirectional propagation remains elusive. Here, we report an approach to solve the aforementioned issues of bulk SPhPs in one go by constructing a heterostructural interface between biaxial van der Waals material (e.g., α-MoO3) and bulk polar dielectric (e.g., SiC, AlN, and GaN). Because of anisotropy-oriented mode couplings, the hybridized SPhPs with a large confinement factor (>100) show in-plane hyperbolicity that has been switched to the orthogonal direction as compared to that in natural α-MoO3. More interestingly, this proof of concept allows steerable and unidirectional polariton excitation by suspending α-MoO3 on patterned SiC air cavities. Our finding exemplifies a generalizable framework to manipulate the flow of nanolight in many other hybrid systems consisting of anisotropic materials and polar dielectrics.

Original languageEnglish
Pages (from-to)3112-3119
Number of pages8
JournalNano Letters
Issue number7
Publication statusPublished - 25 Mar 2021


  • in-plane hyperbolicity
  • nanocavities
  • phonon polaritons
  • polar crystals
  • van der Waals materials

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