We investigated emission and propagation of polaritons in a two dimensionalvan der Waals material hexagonal boron nitride (hBN). Our specific emphasis inthis work is on hyperbolic phonon polariton emission that we investigated bymeans of scattering-type scanning near-field optical microscopy. Real-spacenano-images detail how the polaritons are launched in several commonarrangements including: light scattering by the edges of the crystal, metallicnanostructures deposited on the surface of hBN crystals, as well as randomdefects and impurities. Notably, the scanned tip of the near-field microscopeis itself an efficient polariton launcher. Our analysis reveals that thescanning tips are superior to other types of emitters we have investigated.Furthermore, the study of polariton emission and emission efficiency mayprovide insights for development of polaritonic devices and for fundamentalstudies of collective modes in other van der Waals materials.
展开▼
