Fig. 1. Typical phase distribution of three devices. (a) Phase distribution of spiral phase plate, topological charge l=1; (b) phase distribution of RPS-FZP, control parameter of radial phase shift α=0.2, wavelength λ=1550 nm, and focal length f=120 μm; (c) phase distribution of RSSZP, formed by superposition of (a) and (b)

Fig. 2. Normalized distribution of RSSZPs transfer function obtained at different topological charges and control parameters of radial phase shift. (a) l=1, α=0.2; (b) l=3, α=0.2; (c) l=3, α=0.4

Fig. 3. SEM images of RSSZPs with different topological charges and control parameters of radial phase shift. (a) l=1, α=0.2; (b) l=3, α=0.2; (c) l=3, α=0.4

Fig. 4. An MZI-based experimental test system is used to measure the far-field intensity distribution generated by the RSSZP samples and its interference patterns with Gaussian beam

Fig. 5. Simulated and experimental intensity distributions of RSSZP with different parameters at focal plane. (a)(b) Simulated and experimental measurement results when α is 0.2; (c)(d) simulated and experimental measurement results when α is 0.4

Fig. 6. Simulated and experimental radii of vortex beam generated by RSSZP samples with different control parameters of radial phase shift at different topological charges

Fig. 7. Interference patterns of RSSZP generated perfect vortex beams with spherical wave

Fig. 8. Interference patterns of RSSZP generated perfect vortex beams with plane wave