Tight focusing of the azimuthally polarized light beam for a sharper spot

Abstract This paper presents a method to focus azimuthally polarized vortex light beam by the combination of a vortex phase plate, a binary-phase optical element (BOE) and a high-numerical aperture (NA) objective lens. Our proposed method achieves a smaller spot size than other polarized beams under the same condition. Compared to the system with the annular aperture, the minimum of full width at half-maximum is improved to 0.259λ and the energy conversion efficiency is higher in the proposed method when FWHM