Abstract :

We study the focusing properties of phase modulated azimuthally polarized beam with high numerical aperture lens axicon system is investigated theoretically by vector diffraction theory. We observe that our proposed system generates a sub wavelength focal hole of 0.4λ having large uniform focal depth of 22λ. This kind of non diffracting focal hole is called dark channel, which may have applications in optical trapping, biological, atom optical experiments, high-resolution and atmospheric sciences.