Focus shaping of cylindrically polarized higher-order Generalized Spiraling Bessel beams

Abstract

In this paper, the focusing properties of the cylindrically polarized higher-order Generalized Spiraling Bessel beams (GSBB) by a high numerical aperture (NA) lens system are investigated based on the Richards and Wolf vectorial diffraction method. Intensity distribution of the cylindrically polarized higher-order GSBB at the focal region is derived and analyzed with numerical examples. It is shown that tailored focal patterns with a multi-ringed dark hollow profile and a flat-top profile can be achieved. The central dark region's width, the multi-ringed structure, and the peak intensity and width of the flat-topped profile can be controlled by adjusting properly the polarization rotation angle, the topological charge, the axicon base angle, and the order of the beam. The focusing properties of the beam may find applications in laser scanning microscopy, optical micro-particle trapping, and optical data storage.