title: Square Fresnel zone plate with spiral phase for generating zero axial irradiance.
abstract: A type of square Fresnel zone plate with spiral phase for generating zero axial irradiance is proposed. Diffraction patterns of the zone plates with different generalized topological charges are given by numerical simulation, which also suggests their potential applications in generating hollow beams.
authors.affiliation: Department of Physics, Zhejiang University, Hangzhou 310027, China.
authors.forename: Binzhi
authors.initials: B
authors.lastname: Zhang
authors.forename: Daomu
authors.initials: D
authors.lastname: Zhao