Enhanced photonic spin Hall shift and scattering efficiency through chiral nanoparticles

The photonic spin Hall effect, arising from the spin-orbit interaction of light, has attracted rapt scientific interest owing to its applicability. Due to the limited strength of the spin-orbit interaction, the resulting photonic spin Hall shift (PSHS) is very small. In addition, the low scattering intensity hinders the applicability of the PSHS in higher-dimensional systems. Here, we explore the effect of the chirality of the particle on the far-field PSHS and the scattered intensity. We demonstrate that the chiral particle strongly supports quasi-dual symmetry when the handedness of the incident wave and the sphere match, in contrast to unmatched handedness. Under dual transformation, the spin-orbit interaction is amplified, resulting in enhanced PSHS with a characteristic redshift. Meanwhile, the far-field scattering intensity is optimized without changing the geometry of the particle. The strong spin-orbit interaction in the near-field arises due to the optical singularities in the far-vicinity, which leads to a large effective transverse force. Our results not only provide a route to tune the PSHS and scattering efficiency but might have the potential to characterize the degree of handedness of the nanoparticle.