title: Generation of high-order optical vortices with asymmetrical pinhole plates under plane wave illumination.
abstract: We propose a novel and simple method for generating optical vortex with high topological charge (TC), merely using an asymmetrical pinhole plate illuminated by plane wave. N pinholes are arranged along a particular spiral line around the plate origin, with constant azimuth angle increment and varied radial distances. The radial differences introduce a constant variation of m/N wavelength to the optical paths from the N pinholes to the observation plane origin, and this increases the phases of the transmitting waves by progressively 2mπ/Nand totally 2mπ. We numerically calculate the transmitted light field according to the Fresnel diffraction theory, and find the vortex with TC m around the observation plane origin. The experimental verifications are performed using some self-made asymmetrical pinhole plates fabricated by a femtosecond laser, with the high TC vortices both generated and detected in a Mach-Zehnder type interferometer. The experimental results coincide with the theoretical simulations well.
authors.affiliation: College of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Li
authors.forename: Meina
authors.initials: M
authors.lastname: Zhang
authors.forename: Guotao
authors.initials: G
authors.lastname: Liang
authors.forename: Xing
authors.initials: X
authors.lastname: Li
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Chen
authors.forename: Chuanfu
authors.initials: C
authors.lastname: Cheng