Generating spin-multiplexed elliptic perfect vortex beam arrays with multiple selectable degrees of freedom via single-layer dielectric metasurfaces

The elliptic perfect vortex beam array (EPVBA), involving multiple elliptic or/and circular perfect vortex beams (PVBs) with controllable ellipticity and ring size, carries rich information and holds significant applications in biophotonics and genetic engineering. At present, various PVB arrays based on metasurface have been reported. However, these generated arrays all exhibit similar standard circular shapes, which limits their application in multi-particle manipulation, especially in the manipulation of hybrid irregular biological particles. Thanks to the superposition principle of phase in momentum space, we established the phase equation of spin-multiplexed bifocal EPVBA and designed spin-decoupled dielectric metasurface using TiO2 pillars, achieving two EPVBAs in different longitudinal focal planes. In view of the sensitivity of the metasurface to the spin state of the incident beam, we imposed two sets of arbitrary, fully uncorrelated phase profiles on a single-layer metasurface. The simulation results showed that the designed metasurface can effectively focus and convert incident light into two independent customized EPVBAs along the longitudinal direction, according to the spin state of the incident light. The generated EPVBA consists of PVBs in elliptical or/and circular shapes, supporting controllable ellipticity, topological charge, ring size, the number of PVBs, in-plane position, and longitudinal focal plane. We envision that this method for generating spin-multiplexed multi-parameter customized EPVBAs will have potential applications in optical interconnection, optical encryption, and complex multiparticle manipulation.