Broadband multifunctional metasurfaces enabling polarization multiplexed focused vortex array generation

Metasurfaces are ultrathin artificially engineered structures exquisitely designed to tailor the wavefront, polarization, and amplitude of incident light, offering a versatile platform for implementing compact and integrated photonics devices. Metasurface-based structured light generation has gained considerable attention in the scientific community for its various exotic applications, including optical communication, particle manipulation, and high-resolution lithography. State-of-the-art design techniques include polarization multiplexing, multiple vortices beam generation, and vortex arrays. However, there needs to be more techniques for generating polarization switchable vortex arrays, despite the apparent advantages in significant application fields, necessitating a simple design technique. Here, we present a straightforward design technique utilizing computer-generated holography (CGH) and photonic spin Hall effect (PHSE) to realize a metadevice platform capable of generating broadband multiple optical vortex arrays with switchable polarization output. Our approach involves designing phase masks for the vortex arrays using CGH, which are then encoded onto the metasurface. By leveraging PSHE, the designed metasurfaces produce the desired optical response depending on the input polarization state. Using the proposed design technique as proof of concept, different all-dielectric metasurfaces capable of generating optical vortex arrays of different dimensions are demonstrated. The results verify the effectiveness of the proposed methodology. The design has potential applications in data communications, storage, quantum computation, nanoscale physical manipulation, and microscopy.