Reflected four-zones subwavelength microoptics element for polarization conversion from linear to radial
A four zone subwavelength binary diffraction optical micro element (size of 100x100 mkm) for polarization transformation from linear to radial was calculated and designed. A grating period was equal to 400 nm, a height of the element was equal to 110 nm in a gold film for a wavelength of 633 nm. Simulation by FDTD method and Rayleight-Zommerfeld integral shown, that despite only four zones used for polarization transformation to four different angles there are radial polarized light beam in the far field with smooth angle dependence on the beam circle observation position. Experimentally shown that in the near field, depending on the direction of the axis of the polarizer on the output light are two zones 4-zone trace element for one or the other diagonal, which proves the presence of radial polarization in the reflected beam.