Spin‐Multiplexing Metasurfaces Generate Perfect Quasi‐Fractional Vortex Beams

Abstract

Abstract Perfect fractional vortex beams extend the concept of perfect vortex beams by introducing non‐integer orbital angular momentum (OAM) and exhibit distinctive phase discontinuities, thereby offering additional degrees of freedom for optical communication and particle manipulation. This work demonstrates a spin‐multiplexing metasurface for generating perfect quasi‐fractional vortex beams (PqFVBs). By integrating the phase functions of an axicon, a spiral phase plate, and a Fourier lens into a compact metasurface design, The platform enables the selective generation of PqFVBs under orthogonal circular polarizations. The experimental measurements confirm that the beam radius can be flexibly customized via the phase parameters, specifically, the focal length and numerical aperture, while remaining decoupled from the OAM value. Furthermore, through introducing controllable phase dislocations, the number of donut‐shaped intensity lobes can be precisely engineered. Those structured optical vortices with customizable spatial distribution and topological features will open new avenues for optical communication and optical manipulation.