Generation of vortex beams with multi topological charges, high purity and operating on broadband using a simple silver metasurface

We propose a simple approach to generate vortex beam based on silver metasurface under the incidence of circularly polarized light. The topological charge and purity of result beam is from -4 to 4 and more than 95% respectively, furthermore, it can operate on broadband (800∼1800 nm) including telecom wavelengths. The designed metasurface is composed of ten concentric rings, where each ring is composed of sub-wavelength rectangular apertures with circular array distribution. These rectangular apertures act as localized space-variant linear polarizers and space-variant polarization manipulation can introduce Pancharatnam-Berry (PB) phase. Simulation results show that this design is logically coincidence. The designed metasurface has the advantage of high fabrication tolerance and may be a potential candidate in future integrated optical communication system.