  We study the interconversion between photons and phonons coupled via
radiation pressure in artificial Dirac materials realized by a honeycomb array
of optomechanical cells. In particular we analyze the chiral tunneling of
(photon-phonon) polaritons through an oscillating planar barrier. While a
static barrier accommodates constructively interfering optical or mechanical
waves leading to photon or phonon transmission, an oscillating barrier allows
for inelastic scattering that causes sideband excitations and interference
effects which, in turn, may suppress or revive the light-sound interconversion.
