Curved chirality distributions of optical vortices induced by photonic hooks

Tunable chirality of optical vortices is a research hotspot in recent years due to its important role in light-matter interaction. As a dynamical quantity related to the electric and magnetic fields, the chirality distribution of an optical vortex is generally straight along the beam propagation axis in a homogeneous medium. In this Letter, we present the curved chirality distributions generated by Janus spheres that consist of two halves with different refractive indices under the illumination of optical vortices. The underlying physical mechanism of this curved chirality is the interference of singular points induced by the waves with different phase velocities occur near the Janus sphere. The bending angle and magnitude of such optical chirality can be tailored by altering the hemisphere refractive index, sphere radius, and beam center location. This work is expected to benefit the applications of chiral recognition, detection, and manipulation.