Flexible and achromatic generation of optical vortices by use of vector beam recorded functionalized liquid crystals.

In this study, we investigated the spatial light modulation properties of an optical vortex (OV) generator consisting of azo-dye-doped polymer liquid crystal (ADDLC) and a vector beam illuminator, focusing on flexibility and achromaticity for generating OVs. Uniaxially aligned ADDLC forms three-dimensional photoinduced twisted anisotropic structures under vector beam illumination, and can generate high-order OVs with even-numbered topological charges that correspond to the polarization pattern of the illuminating vector beam. The induced anisotropic structure can be re-initialized by turning it off and changing the vector beam polarization distribution. Simulations showed that the OV generator also has achromatic wavefront modulation properties for the broadband spectrum, and this feature was experimentally demonstrated by using two laser sources whose wavelengths are λ=633  nm and 780 nm, respectively.