Fig. 1. Some modes and their mode groups supported by multimode fiber

Fig. 2. Intelligent mode /mode group recognition model based on LeNet-5 CNN

Fig. 3. Simulation results of recognition of different linear polarization modes under different noise intensities. (a) Optical field of LP11a mode; (b) recognition rate of LP11a mode; (c) variation of multiclass logarithmic loss function; (d) mode prediction result of each mode of recognition model

Fig. 4. Recognition results of linear polarization mode groups obtained by recognition model with noise intensity of 20%. (a) Recognition rate; (b) multiclass logarithmic loss function

Fig. 5. Intensity profiles of multimode superimposed light field in mode group. (a) Simulated light field intensity distributions; (b) intensity distributions of output optical field of multimode fiber

Fig. 6. Experimental setup of multimode fiber mode group receiving system

Fig. 7. Experimental results of mode group classification and recognition when arrays of light detectors of different sizes are used to receive light field. (a) Variation of recognition rate; (b) variation of multiclass logarithmic loss function