Fig. 1. Measured Rayleigh scattering and far-end Fresnel reflection with reflectivity of -14 dB from FC/PC connector for 170 km^[22]

Fig. 2. Sensing results of long range multi-point disturbance events by OFDR^[24]. (a) Rayleigh scattering spectral shift characteristic; (b) V shape sunken characteristic in spatial domain

Fig. 3. Optical interference signals and disturbance locating results before and after polarization compensation^[32]. (a) Before compensation; (b) after compensation

Fig. 4. Schematic diagram of fiber disturbance sensing system based on asymmetric dual Mach-Zehnder interferometers^[34]

Fig. 5. Schematic diagram of distributed acoustic sensing system combining double chirped-pulse and WFBGs^[41]

Fig. 6. Beat frequency signal and phase demodulation results at about 101 km^[41]. (a) 3D spatial-temporal profile; (b) signal power spectrum; (c) signal demodulation result of sensing position 1; (d) signal demodulation result of sensing position 2

Fig. 7. Signals of six intrusion events of waggling fence, cutting fence, climbing fence, knocking cable, crashing fence, and kicking fence^[50]

Fig. 8. Image event locating of color video when irradiancy of natural light is 0.0001 lx using superstar optical image recognition technology. (a) Common camera; (b) Tiandy superstar camera

Fig. 9. Performance of imaging event pattern recognition. (a) Human faces; (b) climbing; (c) gathering

Fig. 10. Distance-time distribution of refraction index in diffusion process of glycerol solution^[65]

Fig. 11. Opto-electronic information fusion recognition sensing