Experimental generation of the longitudinal electric field component on the optical axis with high-numerical-aperture binary axicons

We analytically and numerically show that by introducing the asymmetry into the axicon design it becomes possible to generate the longitudinal electric field (E-field) component on the optical axis for linearly and circularly polarized incident beams. Binary axicons with high numerical aperture (NA) are fabricated in three configurations - axisymmetric and spiral ones, and bi-axicon - by electron beam lithography. Experimental measurements for the near-field diffraction of most common and easy to implement incident beams - linearly and circularly polarized - are conducted. The experimental results agree with the theoretical analysis.