Acoustically-driven surface and hyperbolic plasmon-phonon polaritons in graphene/h-BN heterostructures on piezoelectric substrates

TL;DR

This paper demonstrates how surface acoustic waves can be used to excite and control hybrid plasmon-phonon polaritons in graphene/h-BN heterostructures on piezoelectric substrates, enhancing their properties for mid-IR to THz applications.

Contribution

It introduces a method to dynamically launch and manipulate SPPPs and HPPPs using SAWs in graphene/h-BN heterostructures on piezoelectric substrates, with improved efficiency and tunability.

Findings

SAWs effectively launch SPPPs and HPPPs in heterostructures.

h-BN enhances SPPP lifetime and coupling efficiency.

Hybridized polaritons cover mid-IR to THz range.

Abstract

Surface plasmon polaritons in graphene couple strongly to surface phonons in polar substrates leading to hybridized surface plasmon-phonon polaritons (SPPPs). We demonstrate that a surface acoustic wave (SAW) can be used to launch propagating SPPPs in graphene/h-BN heterostructures on a piezoelectric substrate like AlN, where the SAW-induced surface modulation acts as a dynamic diffraction grating. The efficiency of the light coupling is greatly enhanced by the introduction of the h-BN film as compared to the bare graphene/AlN system. The h-BN interlayer not only significantly changes the dispersion of the SPPPs but also enhances their lifetime. The strengthening of the SPPPs is shown to be related to both the higher carrier mobility induced in graphene and the coupling with h-BN and AlN surface phonons. In addition to surface phonons, hyperbolic phonons appear in the case of multilayer h-BN films leading to hybridized hyperbolic plasmon-phonon polaritons (HPPPs) that are also mediated by the SAW. These results pave the way for engineering SAW-based graphene/h-BN plasmonic devices and metamaterials covering the mid-IR to THz range.