Metasurface-enabled grafted perfect vector vortex beams with trigonometric-function topological charges for high-capacity optical encryption.

Perfect vector vortex beams, distinguished by their unique polarization states and vortex characteristics, have recently become a central focus in advanced photonics research. However, the generation of these vector beams has been limited by static topological charge (TC) configurations and restricted information encryption capabilities. Herein, we present a metasurface-based method employing trigonometric-function topological engineering to generate grafted perfect vector vortex beams (GPVVBs). Through computational analysis, we establish the relationship between the rotation angle and continuously tunable TCs. By dynamically adjusting fractional-order beams through polarizer rotation, we achieve customizable field distributions. Furthermore, we demonstrate the application of GPVVBs in multichannel optical encryption, where the grafted continuous TCs considerably enhance information encryption capacity. This innovative method introduces unprecedented flexibility and holds transformative potential for both optical encryption and high-density communications.