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

2018/07/09 by Chaudhary, Kundan, Tamagnone, Michele, Rezaee, Mehdi +4 · 1 citation
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Optics (physics.optics)

paper · doi:10.48550/arxiv.1807.03339

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 α_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.

Cited by

• Topologically Protected Polaritonic Bound State in the Continuum

Related

• Selective excitation and imaging of ultraslow phonon polaritons in thin hexagonal boron nitride crystals
• Anisotropic polaritons in 2D vdW materials
• Launching Focused and Spatially Confined Phonon-Polaritons in Hexagonal Boron Nitride
• Amplitude- and phase-resolved nano-spectral imaging of phonon polaritons in hexagonal boron nitride
• Active tuning of highly anisotropic phonon polaritons in van der Waals crystal slabs by gated graphene