Spectropolarimetric properties of vortex retarders

Vortex retarders are optical retarders with a uniform retardance, but with a fast axis that varies azimuthally over the area of the optic. This affects the radial and azimuthal polarization components of the incoming beam. The vortex retarders discussed here generate TEM₁₀ and TEM₂₀ Laguerre-Gaussian beams. While several varieties of these vortex retarders exist, designed to function at specific wavelengths, and a few studies have reported their use at those wavelengths, almost no data exists detailing their polarimetric properties outside those wavelengths. Using a Mueller matrix spectropolarimeter with dual-rotating retarders, the polarization properties of four zero-order half-wave vortex retarders have been measured across a broad wavelength range of 300-1100 nm. This data contributes to a more complete description of the spectral properties of these popular retarders.