Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy
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.
Keywords
Cite
@article{arxiv.1807.03339,
title = {Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy},
author = {Kundan Chaudhary and Michele Tamagnone and Mehdi Rezaee and D. Kwabena Bediako and Antonio Ambrosio and Philip Kim and Federico Capasso},
journal= {arXiv preprint arXiv:1807.03339},
year = {2018}
}