Optical vortices: A methodology for generating single-focus phase singularity with binary square spiral zone plates

Since 1992, the British researcher Allen demonstrated theoretically and experimentally that vortex beams have orbital angular momentum, many novel optical physical phenomena have been discovered through the study of optical vortices, and they have a wide application prospect in optical manipulation, optical communication, photonic chip and other fields. By combining the advantages of square spiral zone plate and Gabor zone plate, a novel binary single focused square spiral zone plate is designed to realize the optical vortex with square symmetry and alleviate the influence of the higher order foci in the propagation direction. The theoretical results are consistent with the experimental results. This finding has potential in the applications of multi-particle manipulation and 3D imaging.