Fig. 1. ±2nd order vortex beam superposition state generated with diffraction pattern of different δ. (a) δ=π/2; (b) δ=π; (c) δ=1.5π; (d) δ=2π

Fig. 2. Optical path of generating vortex beam superposition

Fig. 3. Results of generating vortex beam superposition with OAM modes from ±(1‒5). (a) Phase grating patterns loaded by SLM; (b) simulated optical fields; (c) experimental optical fields

Fig. 4. SSIM of vortex beams superposition with different OAM modes generated in experiment with simulated optical fields

Fig. 5. Optical fields of vortex beams superposition with different OAM modes under different offset D

Fig. 6. Optical fields with different center offset D. (a) 0; (b) 0.1 w; (c) 0.2 w; (d) 0.3 w; (e) 0.4 w; (f) 0.5 w

Fig. 7. LICC of vortex beams superposition with different modes under different offset D

Fig. 8. Apparatus for generating a polarization vortex beam and holograms of SLM 1 and SLM 2

Fig. 9. Diffraction patterns obtained by adjusting grating constant T. (a) T=4×10^-4 m; (b) T=3×10^-4 m; (c) T=2×10^-4 m; (d) T=4×10^-5 m

Fig. 10. Polarization measurement results of horizontal polaroid, vertical polaroid, +45°polaroid, and no polaroid at ±1 diffraction order on the horizontal direction for different initial phases σ2 of SLM 1. (a) σ2=π; (b) σ2=1.5π; (c) σ2=2π

Fig. 11. Results of generating polarization vortex beams with adjustable diffraction orders. (a) Generated polarization vortex beams of +2, +1, -1, and -2 diffraction orders, phases and topological charges of SLM 1 and SLM 2; (b) generated polarization vortex beams of +3,+2,and +1 diffraction orders, phases and topological charges of SLM 1 and SLM 2