Spin Hall effect of a light beam in left-handed materials

TL;DR

This paper models the spin Hall effect of light in left-handed materials, revealing that the spin-dependent transverse shift is unaffected by the reversed refractive index, highlighting the unreversed nature of photon spin angular momentum.

Contribution

It introduces a general propagation model for the spin Hall effect in LHMs and uncovers the counterintuitive unreversed spin Hall effect despite negative refractive index.

Findings

Spin-dependent transverse shift depends on refractive index gradient magnitude.

The spin Hall effect remains unreversed in LHMs despite negative index.

Angular shift in LHMs is reversed due to negative diffraction.

Abstract

We establish a general propagation model to describe the spin Hall effect of light beam in left-handed materials (LHMs). A spin-dependent shift of the beam centroid perpendicular to the refractive index gradient for the light beam through an air-LHM interface is demonstrated. For a certain circularly polarized component, whether the transverse shift is positive or negative depends on the magnitude of the refractive index gradient. Very surprisingly, the spin Hall effect in the LHM is unreversed, although the sign of refractive index gradient is reversed. The physics underlying this counterintuitive effect is that the spin angular momentum of photons is unreversed. Further, we reveal that the angular shift in the LHM is reversed due to the negative diffraction. These findings provide alternative evidence for that the linear momentum of photons is reversed, while the spin angular momentum is unreversed in the LHM.