Formation of radially and azimuthally polarized light using space-variant subwavelength metal stripe gratings

We present a unique method for converting circularly polarized light into radially and azimuthally polarized beams. The method is based on the use of computer-generated space-variant subwavelength metal stripe gratings. The elements were realized on GaAs substrates and produced beams with high polarization purity at a wavelength of 10.6 μm. As a result of the conversion, the beams also undergo space-variant phase modification, which has an effect on their propagation. We demonstrate the effect experimentally, and calculate it using full space-variant polarization and phase analysis based on rigorous coupled-wave analysis and Jones calculus.