Fig. 1. Schematic diagram of line-based Sagnac interference structure

Fig. 2. The intervention signal

Fig. 3. Structure of convolution neural network

Fig. 4. Schematic diagram of the experiment system

Fig. 5. Six types of demodulated signal and their power spectrum

Fig. 6. Six kernels after training

Fig. 7. Mel filters

Fig. 8. Features extracted by MFCC method

Fig. 9. Cutting signal after convolution

Fig. 10. Branch tapping signal after convolution

Fig. 11. Cutting features after batch normalized

Fig. 12. Branch tapping features after batch normalized