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arXiv · 1807.03339

Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy

Kundan Chaudhary·Michele Tamagnone·Mehdi Rezaee·D. Kwabena Bediako·Antonio Ambrosio·Philip Kim·Federico Capasso
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Abstract

Van der Waals heterostructures assembled from layers of 2D materials have attracted considerable interest due to their novel optical and electrical properties. Here we report a scattering-type scanning near field optical microscopy study of hexagonal boron nitride on black phosphorous (h-BN/BP) heterostructures, demonstrating the first direct observation of in-plane anisotropic phonon polariton modes in vdW heterostructures. Strikingly, the measured in-plane optical anisotropy along armchair and zigzag crystal axes exceeds the ratio of refractive indices of BP in the x-y plane. We explain that this enhancement is due to the high confinement of the phonon polaritons in h-BN. We observe a maximum in-plane optical anisotropy of {\alpha}_max=1.25 in the 1405-1440 cm-1 frequency spectrum. These results provide new insights on the behavior of polaritons in vdW heterostructures, and the observed anisotropy enhancement paves the way to novel nanophotonic devices and to a new way to characterize optical anisotropy in thin films.

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Kundan Chaudhary, Michele Tamagnone, Mehdi Rezaee, D. Kwabena Bediako, Antonio Ambrosio, Philip Kim, Federico Capasso. 2018-07-09. Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy. https://arxiv.org/abs/1807.03339

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