Probing Hyperbolic and Surface Phonon-Polaritons in 2D materials using Raman Spectroscopy

Abstract

The hyperbolic dispersion relation of phonon-polaritons (PhPol) provides high-momentum states, highly directional propagation, subdiffractional confinement, large optical density of states, and enhanced light-matter interactions. In this work, we use Raman spectroscopy in the convenient backscattering configuration to probe PhPol in GaSe, a 2D material presenting two hyperbolic regions separated by a \textit{double} reststrahlen band. By varying the incidence angle, dispersion relations are revealed. Raman spectra calculations confirm the observation of one surface and two extraordinary guided polaritons and matches the evolution of PhPol frequency as a function of confinement. Resonant excitation close to the excitonic state singularly exalts the scattering efficiency of PhPol. Raman spectroscopy of PhPol in non-centrosymmetry 2D materials does not require any wavevector matching strategies. Widely available, it may accelerate the development of MIR nanophotonic devices and applications.

References in corpus (5)

• Sub-diffractional, volume-confined polaritons in a natural hyperbolic material: hexagonal boron nitride
• Observation of topological polaritons and photonic magic angles in twisted van der Waals bi-layers
• Engineering symmetry breaking in two-dimensional layered materials
• Generalized 4 $\times$ 4 Matrix Formalism for Light Propagation in Anisotropic Stratified Media: Study of Surface Phonon Polaritons in Polar Dielectric Heterostructures
• Insights into hyperbolic phonon polaritons in hBN using Raman scattering from encapsulated transition metal dichalcogenide layers

Cited by in corpus (3)

• Observation of the Breakdown of Optical Phonon Splitting in a Two-dimensional Polar Monolayer
• Phonon-Polaritons in Non-Centrosymmetric Systems: Theory of Terahertz Pump-Optical Probe Spectroscopy
• Correction of broadband terahertz electro-optic sampling with GaSe crystals