Fig. 1. Schematic of fast BOTDA sensing system

Fig. 2. Power spectrum of DOFC

Fig. 3. Structural diagram of fast BOTDA sensing system based on coherent detecting DOFC

Fig. 4. Original BGS and BPS measured at a position of sensing fiber. (a) BGS; (b) BPS

Fig. 5. Spectral distributions along 10 km sensing fiber. (a) BGS; (b) BPS

Fig. 6. BFS distribution measured by sensing system

Fig. 7. Measurement results. (a) Temperature; (b) strain

Fig. 8. Spectra obtained when heating different positions of 10 km fiber. (a) Front-end; (b) middle-part; (c) back-end