We investigated phonon-polaritons in hexagonal boron nitride - a naturally hyperbolic van der Waals material - by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied. Our work may inform future development of polaritonic nanodevices as well as fundamental studies of collective modes in van der Waals materials.
Bibliographical noteFunding Information:
This research is supported by the ONR under grant no. N00014-15-1-2671 and the AFOSR grant no. FA9550-15-1-0478. D.N.B. is an investigator in Quantum Materials funded by the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant no. GBMF4533. P.J.-H. acknowledges support from AFOSR grant number FA9550-11-1-0225 and the Packard Fellowship program.
© 2017 American Chemical Society.
- hexagonal boron nitride
- hyperbolic materials
- Polariton launching
- van der Waals materials