  The origin of spin-orbit interaction of light at a conventional optical
interface lies in the transverse nature of the photon polarization: The
polarizations associated with the plane-wave components experience slightly
different rotations in order to satisfy the transversality after reflection or
refraction. Recent advances in topological photonic materials provide crucial
opportunities to reexamine the spin-orbit interaction of light at the unique
optical interface. Here, we establish a general model to describe the
spin-orbit interaction of light in the photonic Dirac metacrystal. We find a
giant photonic spin Hall effect near the Dirac points when a Gaussian beam
impinges at the interface of the photonic Dirac metacrystal. The giant photonic
spin Hall effect is attribute to the strong spin-orbit interaction of light,
which manifests itself as the large polarization rotations of different
plane-wave components. We believe that these results may provide insight into
the fundamental properties of the spin-orbit interaction of light in the
topological photonic systems.
