Fig. 1. Working principle of fiber grating sensor

Fig. 2. Applications of FBG^[29-32]

Fig. 3. Rayleigh, Brillouin, and Raman scattering light in optical fiber

Fig. 4. Applications of FBG-based high-temperature superconductor. （a） Measurement of superconducting tape quench based on FBG^[39]; （b） measurement of AC loss of high-temperature superconducting tape by using FBG sensor^[49-51]

Fig. 5. Improved Raman scattering fiber technology for measuring quench of high temperature superconducting coils^[54]

Fig. 6. Test of conductor quench using distributed optical fiber based on Rayleigh-backscattering^[60]