Controllable double-helical microstructures by photonic orbital angular momentum for chiroptical response.

Three-dimensional helical microstructures are abundant in nature and can be applied as chiral metamaterials for advanced nanophotonics. Here we report a flexible method to fabricate double-helical microstructures with single exposure by recording the chirality of incident optical vortices. Two coaxial optical vortices can interfere to generate a helical optical field, confirmed by the numerical simulation. The diameters of double-helical microstructures can be tailored by the magnitude of topological charges. This fast manufacturing strategy provides the opportunity to efficiently yield helical microstructures. Finally, the chirality of double-helical microstructures can be reversibly read by optical vortices, demonstrating a strong chiroptical response.