Fig. 1. Diagram of fractional Fourier transform optical path

Fig. 2. Transverse light intensity distributions corressponding to the central coupling and the offset coupling

Fig. 3. Transverse light intensity distributions corressponding to different phase differences between modes

Fig. 4. Curve of the transverse intensity distributions at one point in the center of the coupling along with the phase difference between the modes

Fig. 5. Fractional Fourier modal integrated measurement and control system

Fig. 6. Relation between the fractional Fourier transform order and the modal decomposition

Fig. 7. Influence of the emission distance and the detection distance on the mode field distributions and the MPI

Fig. 8. Mode intensity distributions in x direction and y direction corresponding to spikes in Fig.7(d)

Fig. 9. Relation of intensity distributions of the primary light spotinx direction with the detection distance

Fig. 10. Modes measured by the fractional Fourier transform method ((a)~(d)) and S²method ((e)~(h)) 采用分数阶傅里叶变换法和 法测量得到的模式