Formation of optical needle by high NA lens axicon with dedicated complex spiral phase mask

Abstract

The intensity distribution in the focal region for the tightly focused an azimuthally polarized beam using spiral phase mask and complex phase mask with high NA lens axicon system is studied on the basis of the vector diffraction theory. Here we report a new method that generates optical needle like transversally polarized beam with sub diffraction spot size \((0.39\,\lambda )\) and propagates without divergence over a long distance (of about \(15.8\,\lambda \)) in free space for NA \(=\) 0.95. The authors expect such investigation is worthwhile for optical manipulation, beam shaping and optical trapping applications.