Fig. 1. Experimental setup for measuring power fluctuation and scintillation index

Fig. 2. CGHs used by SLM1 and SLM2. (a) CGH sequence used by SLM1 is composed of N_k (N_k=800) frames, which can produce multi-mode vortex beams in two superposition modes; (b) CGH used by SLM2 can generate OAM mode light field with topological charge of S

Fig. 3. Averaged light intensity diagrams of single-mode and incoherently superposed multi-mode vortex beams. (a) Single-mode vortex beams; (b) incoherently superposed multi-mode vortex beams

Fig. 4. Real-time power comparison diagrams of single-mode and incoherently superposed multi-mode vortex beams. (a) Single-mode vortex beam (L=3); (b) incoherently superposed multi-mode vortex beam (L=2,3,4)

Fig. 5. Power fluctuation of single-mode vortex beam and two types of multi-mode vortex beams. (a) Power fluctuation of signal OAM mode S=0; (b) power fluctuation of signal OAM mode S=3; (c) power fluctuation of signal OAM mode S=6; (d) single-mode vortex power fluctuation with different topological charges; (e) incoherently superposed multi-mode vortex power fluctuation with different topological charges; (f) coherently superposed multi-mode vortex power fluctuation with different topological charges

Fig. 6. Scintillation indexes of single-mode vortex beam and two types of multi-mode vortex beams. (a) Scintillation index of signal OAM mode S=0; (b) scintillation index of signal OAM mode S=3; (c) scintillation index of signal OAM mode S=6; (d) scintillation index of single-mode vortex beams with different topological charges; (e) scintillation index of incoherently superposed multimode vortex beams for different topological charges; (f) scintillation index of coherently superposed multimode vortex beams for different topological charges

Fig. 7. Scintillation indexes of three types of vortex beams for different propagation distances. (a) Scintillation index of signal OAM mode S=0 for different z; (b) scintillation index of signal OAM mode S=3 for different z; (c) scintillation index of signal OAM mode S=6 for different z