Controllable propagation and transformation of chiral intensity field at focus

Abstract

As an intrinsic feature of the optical field, chirality could induce many novel phenomena due to the interaction between chiral light and matter. Thus, the generation of optical fields possessing 2D or 3D chiral intensity patterns, called chiral intensity fields, has been widely studied. However, the control of chiral intensity field along the optical axis is still a challenge. Here, we propose a method to manipulate the axial propagation property of a focused chiral intensity field. Two modulation effects are realized: extended chiral intensity field with a focal depth >2<i>λ</i> at 90% mode correlation and tunable transformation of chirality during the axial propagation. This method is simple, stable, and easy to perform and therefore offers broad applications especially in optical tweezers and metamaterial fabrication.