Optical vortices, a type of structured beam with helical phase wavefronts and ‘doughnut’-shaped intensity distributions, have been used to fabricate chiral structures in metals and spiral patterns in anisotropic polarization-dependent azobenzene polymers. However, in isotropic polymers, the fabricated microstructures are typically confined to non-chiral cylindrical geometry due to the two-dimensional ‘doughnut’-shaped intensity profile of the optical vortices. Here we develop a powerful strategy to realize chiral microstructures in isotropic material by coaxial interference of a vortex beam and a plane wave, which produces three-dimensional (3D) spiral optical fields. These coaxial interference beams are generated by designing contrivable holograms consisting of an azimuthal phase and an equiphase loaded on a liquid-crystal spatial light modulator. In isotropic polymers, 3D chiral microstructures are achieved under illumination using coaxial interference femtosecond laser beams with their chirality controlled by the topological charge. Our further investigation reveals that the spiral lobes and chirality are caused by interfering patterns and helical phase wavefronts, respectively. This technique is simple, stable and easy to perform, and it offers broad applications in optical tweezers, optical communications and fast metamaterial fabrication.

Significance: Optical chirality by light–matter interaction is a powerful strategy for discriminating the chirality of materials in modern physics. Here we present a vortex-dependent approach to yield a direct chiroptical response with monochromatic light. The chiroptical signal of ∼120% is obtained on intrinsically chiral microstructures by optical vortices in the visible range. The chiroptical properties of microstructures can be flexibly controlled by tuning their geometric features. We further demonstrate the strong chiral light–matter interaction by optical vortices for sensitively detecting optical chirality of molecules.