Tight focusing of a sector-wise azimuthally polarized optical vortex

In this article we numerically investigated tightly focusing an optical vortex with sector-wise azimuthal polarization by a Fresnel zone plate with numerical aperture NA = 0.95. The focal spot produced by a six-sector beam was shown practically not to differ from the focus produced by an ideal azimuthally polarized optical vortex, with the difference in the size of the focal spots not exceeding 0.001 of the wavelength of light.