a Beijing Key Laboratory for Optoelectronic Measurement Technology, Beijing Information Science and Technology University, Beijing 100192, China; b Beijing Engineering Research Center of Optoelectronic Information and Instruments, Beijing Information Science and Technology University, Beijing 100192, China
Abstract Tight focusing of axially symmetric polarized vortex beams is studied numerically based on vector diffraction theory. The mathematical expressions for the focused fields are derived. Simulation results show that the focused fields and phase distributions at focus are largely influenced by both the polarization order and topological charge of the incident beams. Moreover, focal spots with flat-topped or tightly-focused patterns can be flexibly achieved by carefully choosing the polarization order and the topological charge, which confirms the potential of such beams in wide applications, such as optical tweezers, laser printing, lithography, and material processing.
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos. 61108047 and 61240057), the Program for New Century Excellent Talents in University, China (Grant No. NCET-13-0667), and the Beijing Excellent Talent TrainingProject, China (Grant No. 2011D005007000008).
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