Focus shaping effect of annular cylindrical vector beam generated by novel polarized convertor

Based on the diffractive vector theory, the focusing properties of annular cylindrical vector beams generated by the novel polarized convertor are investigated. By the combination of the vortex phase plate eimφ and the phase variety parameter cosφ + ihsinφ which exists naturally in the CV beams, the intensity pattern at the focus can be tailored. Flattop spot and light intensity with pure transverse and longitudinal component are formed in the focal region. More interestingly, tunable dark focal spot is also achieved. By changing h, the light intensity in the center of spot can be changed at will while the outer ring of spot remains the same. This works are important for microscope imaging and optical lithography, particle manipulation, electric acceleration etc.