Generation of vector beam with tandem helical undulators

We propose a scheme to produce structured light in synchrotron light sources. In this scheme, light beams from two undulators are superposed by using a technique akin to the cross undulator. We demonstrate that a vector beam, in which the polarization direction varies with the azimuthal angle about the beam axis, is produced by superposing harmonic radiation from two helical undulators in tandem. Although this scheme is demonstrated in the ultraviolet range at the low-energy synchrotron UVSOR-III, it can be applied to high-energy synchrotrons to produce vector x-ray beams, which would open a new field in the application of synchrotron radiation. Published by AIP Publishing.