Multichannel vortex beam array based on quarter-wave plate metasurface

Beams carrying spin angular momentum (SAM) and orbital angular momentum (OAM) have created many application opportunities in optical communication, micromanipulation, quantum optics, and other fields. Beam arrays carrying multiple different angular momentum (AM) have attracted widespread attention due to their application prospects in high-dimensional information storage and high-security information encryption. Traditional optical devices have complex structures and large systems and are not conducive to integration. We proposed a method of using a quarter-wave plate (QWP) metasurface to regulate photon AM to generate a vortex beam array with two kinds of circularly polarized light at the wavelength 1550 nm. Different from the traditional method of using a half-wave plate to generate a vortex beam array, the use of transmission phase and geometric phase through QWP metasurface can not only realize the flexible modulation of SAM and OAM but also play a role in the optimization of partial circularly polarized light phase by geometric phase, which facilitates the generation of high-quality vortex beam arrays. Compared with traditional QWP metasurfaces that rely solely on the transmission phase, the introduction of a geometric phase can increase the number of channels without losing the quality of vortex beams. The simulation results verify the feasibility and advantages of the theory. Finally, a manufacturing tolerance analysis was conducted on the designed metasurface, verifying the feasibility of using the designed metasurface to regulate AM. We first attempt to generate circularly polarized vortex beam arrays using QWP metasurface and provide an effective idea for the regulation of optical AM.