  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.
