Chiro-optical fields with asymmetric orbital angular momentum and polarization.

In this paper, we proposed a flexible method for generating asymmetric chiro-optical fields. Different from most of the chiro-optical fields superimposed by vortex beams which are rotationally symmetric, the asymmetric chiro-optical field has a locally controllable orbital angular momentum (OAM) and polarization state. By using a helix phase plate (HPP) calculated based on coordinates transformation of the perfect vortex, the OAM controllability of a single chiro-optical field could be achieved. Then, by using the transformation matrix method, several discrete chiro-optical fields with different rotation angles and topological charges were stitched together as a multi-lobed chiro-optical field with asymmetric OAM on each side-lobe. Furthermore, we designed two HPPs that can be loaded into two spatial light modulators to modulate the polarization state of each side-lobe of the asymmetric chiro-optical field independently. The proposed asymmetric chiro-optical field breaks the characteristics of uniform OAM and polarization distribution of conventional chiro-optical fields, which may have potential applications in optical tweezers, communications, and enantiomer-selective sensing.