Chirality-assisted spin Hall effect of light in the vicinity of the quasi-antidual symmetry mode of a chiral sphere

Abstract

The spin Hall shift (SHS) refers to a transverse shift in the scattering plane during the spin-orbit interaction (SOI). SHS is considerably small when light is scattered by a sphere due to the absence of unidirectional scattering. This work shows that the chiral property of a sphere can offer a platform to optimize the SOI by achieving nearly zero forward scattering with significant backward scattering. As a result, a polarization transformation takes place and the scattered field transfers its maximum spin angular momentum to orbital angular momentum. Consequently, an enhanced transversal shift is observed due to the momentum conservation of the scattered field. The results reveal that the shift strongly depends on the handedness of the chiral sphere and the helicity of the incident beam. Thus, offering an alternative paradigm for the quantitative measurement of chirality parameters of a single chiral nanoparticle. We hope that these results will potentially shed new light on the SOI of various forms that can find potential applications such as optical sensing, chiral resolution of single nanoparticles, precision measurements, and the manipulation of subwavelength nanoparticles.