  The photonic spin Hall effect (SHE) can be regarded as a direct optical
analogy of the SHE in electronic systems where a refractive index gradient
plays the role of electric potential. However, it has been demonstrated that
the effective refractive index fails to adequately explain the lightmatter
interaction in atomically thin crystals. In this paper, we examine the
spin-orbit interaction on the surface of the freestanding atomically thin
crystals. We find that it is not necessary to involve the effective refractive
index to describe the spin-orbit interaction and the photonic SHE in the
atomically thin crystals. The strong spin-orbit interaction and giant photonic
SHE have been predicted, which can be explained as the large polarization
rotation of plane-wave components in order to satisfy the transversality of
photon.

Optics