Fig. 1. Schematic diagram of reflective meta-atom with rotation angle

Fig. 2. Schematic diagram of reflective meta-atom

Fig. 3. Schematic diagram of OAM vortex wave generation based on metasurface

Fig. 4. Schematic diagram of calculating phase distribution of reflective metasurface

Fig. 5. Simulation settings and results of reflective meta-atom

Fig. 6. Topology of proposed metasurface with OAM mode of l=±2

Fig. 7. Amplitudes and phases of simulated near-field vortex waves for l=−2 at different frequencies

Fig. 8. 3D far-field radiation diagram of vortex waves for l=−2 at different frequencies

Fig. 9. OAM spectrum weight for simulated results at different frequencies

Fig. 10. Topology of optimized metasurface with OAM mode of l=±2

Fig. 11. Near-field observation and corresponding spectral analyses of vortex wave at different frequencies reflected by rectangular metasurface

Fig. 12. Near-field observation and corresponding spectral analyses of vortex wave at different frequencies reflected by circular metasurface

Fig. 13. Rotation angle error distribution, near-field observation and corresponding spectral analyses of vortex wave at center frequencies