Flattop shaped creation based on strong focusing of circularly polarized vortex beams

Abstract

Because circularly polarized vortex beam can be characterized as the linear superposition of radially polarized and azimuthally polarized components in the cylindrical coordinate. When investigating the focusing properties of the circularly polarized vortex beam, we must consider radially polarized vortex beam has azimuthal component and azimuthally polarized vortex beam has radial component after focusing. Due to this reason, the focusing properties of the circularly polarized vortex beams have been restudied based on the amending the tightly focusing formula of the circularly polarized vortex beam. The results show that not only the focusing of the single handedness of the circularly polarized vortex beam but also the focusing of superposition of two circularly polarized vortex beams with different topological charges and different handedness can generate the flat-top intensity shape. We also investigate the influence of amplitude ratio, waist radius and the aperture blocking on the flat-topped focus size.