title: Generation of dipole vortex array using spiral Dammann zone plates.
abstract: We propose a new diffractive optical element, called a spiral Dammann zone plate (SDZP), to generate a series of dipole vortices along the optical axis in the focal region of a focusing objective. By combining this SDZP and another Dammann grating, we describe the generation of three-dimensional dipole vortex arrays in the focal volume of an objective. For experimental demonstration, a 1×5 SDZP with base charge of l=1 is fabricated by using lithography and wet-etching techniques, and a 1×5 coaxial dipole vortex array is achieved for an objective of NA=0.127. Furthermore, by combining the 1×5 SDZP and another 5×5 Dammann grating, a 5×5×5 dipole vortex array is also experimentally demonstrated. The results show that topological charges of these 5×5 vortex arrays on five coaxial planes could be tunable by selecting a vortex beam carrying different charge as the incident field.
authors.affiliation: Laboratory of Information Optics and Optoelectronics Techniques, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, P.O. Box 800-211, Shanghai 201800, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Yu
authors.forename: Changhe
authors.initials: C
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Jia
authors.forename: Anduo
authors.initials: A
authors.lastname: Hu
authors.forename: Wugang
authors.initials: W
authors.lastname: Cao
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Wang