Effect of Complex Phase Plate on Tight Focusing of Azimuthally Polarized Dark and Anti-Dark Gaussian Beam

In this work, the focusing of azimuthally polarized Dark and Anti-Dark Gaussian (DADG) beams, through a high numerical-aperture (NA). Lens is investigated throretically by using the vector diffraction theory. It is noted upon suitable phase modulation for the incident DADG beam, the intensity distribution in the focal region can be tuned to be a focal hole segment with multiple focal holes separated with different axial distances. Such a chain of focal hole segment is useful for multiple trapping of low refractive index particle and also an erase beam for STED microscopy with screening rate.