2016/04/30 by Alexander J Giles, Alexander J. Giles, Siyuan Dai +19 · 2 citations
Engineering · Physics and Astronomy · #Atomic physics #Boron nitride #Condensed matter physics #Dielectric #Field (mathematics) #Geometry #Graphene #Hexagonal boron nitride #Materials science #Molecular physics #Nanotechnology #Near-Field Optical Microscopy #Optics #Optoelectronics #Phonon #Physics #Plasmonic and Surface Plasmon Research #Polariton #Resonance (particle physics) #Thermal Radiation and Cooling Technologies #Zigzag #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1021/acs.nanolett.6b01341
Accepted for publication in Nano Letters
openalex publication_date 2016/05/09 · arxiv created 2016/05/10 · arxiv updated 2016/06/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We use scanning near-field optical microscopy to study the response of hexagonal boron nitride nanocones at infrared frequencies, where this material behaves as a hyperbolic medium. The obtained images are dominated by a series of "hot" rings that occur on the sloped sidewalls of the nanocones. The ring positions depend on the incident laser frequency and the nanocone shape. Both dependences are consistent with directional propagation of hyperbolic phonon-polariton rays that are launched at the edges and zigzag through the interior of the nanocones, sustaining multiple internal reflections off the sidewalls. Additionally, we observe a strong overall enhancement of the near-field signal at discrete resonance frequencies. These resonances attest to low dielectric losses that permit coherent standing waves of the subdiffractional polaritons to form. We comment on potential applications of such shape-dependent resonances and the field concentration at the hot rings.