Forming near-field helical intensity using a binary vortical axicon

Abstract

A helical intensity distribution was created in a near-field when Gaussian laser beam was focused by a binary phase spiral axicon with high numerical aperture. It was shown by 3D-simlation using the Comsol software and natural experiments with near-field microscope NT-MDT Integra Spectra. Experimental measurements and numerical simulations are in good agreement.