Engineering phonon polaritons in van der Waals heterostructures to enhance in-plane optical anisotropy

• DOI: 10.1126/sciadv.aau7171
• Publication Date: 2019-04-12T23:16:25Z
• Authors: Kundan Chaudhary; Michele Tamagnone; Mehdi Rezaee; D. Kwabena Bediako; Antonio Ambrosio; Philip Kim; Federico Capasso
• Keywords: Nanophotonics; Zigzag; Supercell

Van der Waals (vdW) heterostructures assembled from layers of two-dimensional materials have attracted considerable interest due to their novel optical and electrical properties. Here, we report a scattering-type scanning near-field microscopy study hexagonal boron nitride on black phosphorus (h-BN/BP) heterostructures, demonstrating the first direct observation in-plane anisotropic phonon polariton modes in vdW heterostructures. Notably, measured anisotropy along armchair zigzag crystal axes exceeds ratio refractive indices BP x-y plane. We explain that this enhancement is high confinement polaritons h-BN. observe maximum αmax = 1.25 frequency spectrum at 1405 1440 cm-1. These results provide new insights into behavior observed paves way nanophotonic devices characterize thin films.