Fig. 1. LG beams with topological charges of +2 and +5. (a) Topological charge is +2; (b) Topological charge is +5

Fig. 2. The mapping relationship between LG beam and data

Fig. 3. Phase screen of r₀=0.24 m and r₀=0.09 m and normalized phase screen.

(a) Phase screen of r₀=0.24 m; (b) Phase screen of r₀=0.09 m;

(c) Normalized phase screen of r₀=0.24 m; (d) Normalized phase screen of r₀=0.09 m

Fig. 4. Transfer learning architecture based on VGG16

Fig. 5. System structure

Fig. 6. Intensity diagram of ±5 order LG beam when D/r₀ is 1.5 and 4. (a) D/r₀=1.5; (b) D/r₀=4

Fig. 7. Training accuracy and validation accuracy of different recognition models. (a) Based on transfer learning; (b) Based on VGG16

Fig. 8. Confusion matrix of transfer learning model in different turbulent environment. (a) D/r₀=1.5 ; (b) D/r₀=4

Fig. 9. Confusion matrix of VGG16 model in different turbulent environment. (a) D/r₀=1.5; (b) D/r₀=4