Focus shaping of radially polarized Bessel–Gaussian vortex beam by annular helical axicon

Abstract

Focus shaping of radially polarized Bessel–Gaussian Vortex (RPBGV) beam with annular helical axicon is theoretically investigated based on vector diffraction theory. Different focal shapes such as focal hole and optical cage are generated in the focal region of the helical axicon by carefully choosing the values of beam and optical system parameters. By altering the incident beam and optical system parameters such as topological charge of the beam $m$, topological charge of the helical axicon $p$, numerical aperture, and annular obstruction the focused beam profile changes and reformed. Furthermore, the annular obstruction have implemented the focal region components to redistribute These focal shapes may have wide applications in trapping and manipulation of particles.