Optical vortex generator with linearly polarized light illumination

A device is designed for generating the near-field optical vortex (NFOV) using linearly polarized light illumination. This optical vortex generator consists of 18 homogeneous rectangular holes. Each rectangular hole can be modeled as a pair of orthogonal dipoles with pi/2 and -pi/2 phase differences under 45 deg and -45 deg polarized light illuminations, respectively. The superposition of the surface plasmon polaritons excited by these 18 homogeneous rectangular holes can create an optical vortex at the center of the generator, and the topological charge of the optical vortex can be changed by arranging these rectangular holes in a different trajectory. Both theoretical analysis and numerical simulation are used to investigate the properties of the NFOV generator. The numerical results demonstrate that the NFOV generated by the device is reliable, efficient, and flexible. This NFOV generator can be applied in optical manipulation. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)