Surface phonon polariton responses of hexagonal sapphire crystals with non-polar and semi-polar crystallographic planes

Abstract

The surface phonon polariton (SPhP) characteristics of hexagonal sapphire crystals with non-polar and semi-polar crystallographic planes are investigated. A formulation that considers the effects of crystal orientation is employed to calculate the SPhP dispersion curves of the samples. The SPhP dispersion curves indicate that the SPhP responses of sapphire crystals in non-polar and semi-polar orientations are directionally sensitive. Resonance frequencies and spectral strengths of the SPhP modes can be modulated simply by tuning the angular positions of the samples. The validity of the theoretical results is confirmed by the polarized infrared attenuated total reflection measurements.

Confined transverse electric phonon polaritons in hexagonal boron nitrides

“…The surface conductivity in equation ( 3) can be attributed to the existence of an ultrathin dielectric slab at the interface. For example, for an ultrathin hBN slab, the effective surface conductivity can be obtained from its relative in-plane permittivity 𝜀 𝑟⊥,ℎ𝐵𝑁 (𝜔) (the component of permittivity perpendicular to the z direction or the optic axis [27,28] of hBN) as follows:…”

Phonon polaritons in van der Waals polar heterostructures for broadband strong light–matter interactions

“…Furthermore, our theoretical studies reveal the strong coupling between multiple molecules and PhPs with broadband responses in this platform, highlighting its potential for manipulating infrared light-matter interactions. Given the abundance of bulk polar crystals such as sapphire 36,37 and calcite, 38 and the availability of thin layers of emerging vdW polar materials like V 2 O 5 25 and SnO 2 , 39 our integrated heterostructures hold tremendous promise for developing PhP-based optical elements, 40 circuits, 41 and devices with large bandwidth and diverse functionalities. 42,43…”